vchiq_arm: Avoid use of mutex in add_completion

[mirror_ubuntu-zesty-kernel.git] / drivers / staging / vc04_services / interface / vchiq_arm / vchiq_arm.c

/**
 * Copyright (c) 2014 Raspberry Pi (Trading) Ltd. All rights reserved.
 * Copyright (c) 2010-2012 Broadcom. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the above-listed copyright holders may not be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * ALTERNATIVELY, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2, as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/bug.h>
#include <linux/semaphore.h>
#include <linux/list.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <soc/bcm2835/raspberrypi-firmware.h>

#include "vchiq_core.h"
#include "vchiq_ioctl.h"
#include "vchiq_arm.h"
#include "vchiq_debugfs.h"
#include "vchiq_killable.h"

#define DEVICE_NAME "vchiq"

/* Override the default prefix, which would be vchiq_arm (from the filename) */
#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX DEVICE_NAME "."

#define VCHIQ_MINOR 0

/* Some per-instance constants */
#define MAX_COMPLETIONS 128
#define MAX_SERVICES 64
#define MAX_ELEMENTS 8
#define MSG_QUEUE_SIZE 128

#define KEEPALIVE_VER 1
#define KEEPALIVE_VER_MIN KEEPALIVE_VER

/* Run time control of log level, based on KERN_XXX level. */
int vchiq_arm_log_level = VCHIQ_LOG_DEFAULT;
int vchiq_susp_log_level = VCHIQ_LOG_ERROR;

#define SUSPEND_TIMER_TIMEOUT_MS 100
#define SUSPEND_RETRY_TIMER_TIMEOUT_MS 1000

#define VC_SUSPEND_NUM_OFFSET 3 /* number of values before idle which are -ve */
static const char *const suspend_state_names[] = {
        "VC_SUSPEND_FORCE_CANCELED",
        "VC_SUSPEND_REJECTED",
        "VC_SUSPEND_FAILED",
        "VC_SUSPEND_IDLE",
        "VC_SUSPEND_REQUESTED",
        "VC_SUSPEND_IN_PROGRESS",
        "VC_SUSPEND_SUSPENDED"
};
#define VC_RESUME_NUM_OFFSET 1 /* number of values before idle which are -ve */
static const char *const resume_state_names[] = {
        "VC_RESUME_FAILED",
        "VC_RESUME_IDLE",
        "VC_RESUME_REQUESTED",
        "VC_RESUME_IN_PROGRESS",
        "VC_RESUME_RESUMED"
};
/* The number of times we allow force suspend to timeout before actually
** _forcing_ suspend.  This is to cater for SW which fails to release vchiq
** correctly - we don't want to prevent ARM suspend indefinitely in this case.
*/
#define FORCE_SUSPEND_FAIL_MAX 8

/* The time in ms allowed for videocore to go idle when force suspend has been
 * requested */
#define FORCE_SUSPEND_TIMEOUT_MS 200


static void suspend_timer_callback(unsigned long context);


typedef struct user_service_struct {
        VCHIQ_SERVICE_T *service;
        void *userdata;
        VCHIQ_INSTANCE_T instance;
        char is_vchi;
        char dequeue_pending;
        char close_pending;
        int message_available_pos;
        int msg_insert;
        int msg_remove;
        struct semaphore insert_event;
        struct semaphore remove_event;
        struct semaphore close_event;
        VCHIQ_HEADER_T * msg_queue[MSG_QUEUE_SIZE];
} USER_SERVICE_T;

struct bulk_waiter_node {
        struct bulk_waiter bulk_waiter;
        int pid;
        struct list_head list;
};

struct vchiq_instance_struct {
        VCHIQ_STATE_T *state;
        VCHIQ_COMPLETION_DATA_T completions[MAX_COMPLETIONS];
        int completion_insert;
        int completion_remove;
        struct semaphore insert_event;
        struct semaphore remove_event;
        struct mutex completion_mutex;

        int connected;
        int closing;
        int pid;
        int mark;
        int use_close_delivered;
        int trace;

        struct list_head bulk_waiter_list;
        struct mutex bulk_waiter_list_mutex;

        VCHIQ_DEBUGFS_NODE_T debugfs_node;
};

typedef struct dump_context_struct {
        char __user *buf;
        size_t actual;
        size_t space;
        loff_t offset;
} DUMP_CONTEXT_T;

static struct cdev    vchiq_cdev;
static dev_t          vchiq_devid;
static VCHIQ_STATE_T g_state;
static struct class  *vchiq_class;
static struct device *vchiq_dev;
static DEFINE_SPINLOCK(msg_queue_spinlock);

static const char *const ioctl_names[] = {
        "CONNECT",
        "SHUTDOWN",
        "CREATE_SERVICE",
        "REMOVE_SERVICE",
        "QUEUE_MESSAGE",
        "QUEUE_BULK_TRANSMIT",
        "QUEUE_BULK_RECEIVE",
        "AWAIT_COMPLETION",
        "DEQUEUE_MESSAGE",
        "GET_CLIENT_ID",
        "GET_CONFIG",
        "CLOSE_SERVICE",
        "USE_SERVICE",
        "RELEASE_SERVICE",
        "SET_SERVICE_OPTION",
        "DUMP_PHYS_MEM",
        "LIB_VERSION",
        "CLOSE_DELIVERED"
};

vchiq_static_assert(ARRAY_SIZE(ioctl_names) ==
                    (VCHIQ_IOC_MAX + 1));

static void
dump_phys_mem(void *virt_addr, uint32_t num_bytes);

/****************************************************************************
*
*   add_completion
*
***************************************************************************/

static VCHIQ_STATUS_T
add_completion(VCHIQ_INSTANCE_T instance, VCHIQ_REASON_T reason,
        VCHIQ_HEADER_T *header, USER_SERVICE_T *user_service,
        void *bulk_userdata)
{
        VCHIQ_COMPLETION_DATA_T *completion;
        int insert;
        DEBUG_INITIALISE(g_state.local)

        insert = instance->completion_insert;
        while ((insert - instance->completion_remove) >= MAX_COMPLETIONS) {
                /* Out of space - wait for the client */
                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                vchiq_log_trace(vchiq_arm_log_level,
                        "add_completion - completion queue full");
                DEBUG_COUNT(COMPLETION_QUEUE_FULL_COUNT);

                if (down_interruptible(&instance->remove_event) != 0) {
                        vchiq_log_info(vchiq_arm_log_level,
                                "service_callback interrupted");
                        return VCHIQ_RETRY;
                }

                if (instance->closing) {
                        vchiq_log_info(vchiq_arm_log_level,
                                "service_callback closing");
                        return VCHIQ_SUCCESS;
                }
                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
        }

        completion = &instance->completions[insert & (MAX_COMPLETIONS - 1)];

        completion->header = header;
        completion->reason = reason;
        /* N.B. service_userdata is updated while processing AWAIT_COMPLETION */
        completion->service_userdata = user_service->service;
        completion->bulk_userdata = bulk_userdata;

        if (reason == VCHIQ_SERVICE_CLOSED) {
                /* Take an extra reference, to be held until
                   this CLOSED notification is delivered. */
                lock_service(user_service->service);
                if (instance->use_close_delivered)
                        user_service->close_pending = 1;
        }

        /* A write barrier is needed here to ensure that the entire completion
                record is written out before the insert point. */
        wmb();

        if (reason == VCHIQ_MESSAGE_AVAILABLE)
                user_service->message_available_pos = insert;

        instance->completion_insert = ++insert;

        up(&instance->insert_event);

        return VCHIQ_SUCCESS;
}

/****************************************************************************
*
*   service_callback
*
***************************************************************************/

static VCHIQ_STATUS_T
service_callback(VCHIQ_REASON_T reason, VCHIQ_HEADER_T *header,
        VCHIQ_SERVICE_HANDLE_T handle, void *bulk_userdata)
{
        /* How do we ensure the callback goes to the right client?
        ** The service_user data points to a USER_SERVICE_T record containing
        ** the original callback and the user state structure, which contains a
        ** circular buffer for completion records.
        */
        USER_SERVICE_T *user_service;
        VCHIQ_SERVICE_T *service;
        VCHIQ_INSTANCE_T instance;
        int skip_completion = 0;
        DEBUG_INITIALISE(g_state.local)

        DEBUG_TRACE(SERVICE_CALLBACK_LINE);

        service = handle_to_service(handle);
        BUG_ON(!service);
        user_service = (USER_SERVICE_T *)service->base.userdata;
        instance = user_service->instance;

        if (!instance || instance->closing)
                return VCHIQ_SUCCESS;

        vchiq_log_trace(vchiq_arm_log_level,
                "service_callback - service %lx(%d,%p), reason %d, header %lx, "
                "instance %lx, bulk_userdata %lx",
                (unsigned long)user_service,
                service->localport, user_service->userdata,
                reason, (unsigned long)header,
                (unsigned long)instance, (unsigned long)bulk_userdata);

        if (header && user_service->is_vchi) {
                spin_lock(&msg_queue_spinlock);
                while (user_service->msg_insert ==
                        (user_service->msg_remove + MSG_QUEUE_SIZE)) {
                        spin_unlock(&msg_queue_spinlock);
                        DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                        DEBUG_COUNT(MSG_QUEUE_FULL_COUNT);
                        vchiq_log_trace(vchiq_arm_log_level,
                                "service_callback - msg queue full");
                        /* If there is no MESSAGE_AVAILABLE in the completion
                        ** queue, add one
                        */
                        if ((user_service->message_available_pos -
                                instance->completion_remove) < 0) {
                                VCHIQ_STATUS_T status;
                                vchiq_log_info(vchiq_arm_log_level,
                                        "Inserting extra MESSAGE_AVAILABLE");
                                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                                status = add_completion(instance, reason,
                                        NULL, user_service, bulk_userdata);
                                if (status != VCHIQ_SUCCESS) {
                                        DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                                        return status;
                                }
                        }

                        DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                        if (down_interruptible(&user_service->remove_event)
                                != 0) {
                                vchiq_log_info(vchiq_arm_log_level,
                                        "service_callback interrupted");
                                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                                return VCHIQ_RETRY;
                        } else if (instance->closing) {
                                vchiq_log_info(vchiq_arm_log_level,
                                        "service_callback closing");
                                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                                return VCHIQ_ERROR;
                        }
                        DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                        spin_lock(&msg_queue_spinlock);
                }

                user_service->msg_queue[user_service->msg_insert &
                        (MSG_QUEUE_SIZE - 1)] = header;
                user_service->msg_insert++;

                /* If there is a thread waiting in DEQUEUE_MESSAGE, or if
                ** there is a MESSAGE_AVAILABLE in the completion queue then
                ** bypass the completion queue.
                */
                if (((user_service->message_available_pos -
                        instance->completion_remove) >= 0) ||
                        user_service->dequeue_pending) {
                        user_service->dequeue_pending = 0;
                        skip_completion = 1;
                }

                spin_unlock(&msg_queue_spinlock);

                up(&user_service->insert_event);

                header = NULL;
        }

        if (skip_completion) {
                DEBUG_TRACE(SERVICE_CALLBACK_LINE);
                return VCHIQ_SUCCESS;
        }

        DEBUG_TRACE(SERVICE_CALLBACK_LINE);

        return add_completion(instance, reason, header, user_service,
                bulk_userdata);
}

/****************************************************************************
*
*   user_service_free
*
***************************************************************************/
static void
user_service_free(void *userdata)
{
        kfree(userdata);
}

/****************************************************************************
*
*   close_delivered
*
***************************************************************************/
static void close_delivered(USER_SERVICE_T *user_service)
{
        vchiq_log_info(vchiq_arm_log_level,
                "close_delivered(handle=%x)",
                user_service->service->handle);

        if (user_service->close_pending) {
                /* Allow the underlying service to be culled */
                unlock_service(user_service->service);

                /* Wake the user-thread blocked in close_ or remove_service */
                up(&user_service->close_event);

                user_service->close_pending = 0;
        }
}

/****************************************************************************
*
*   vchiq_ioctl
*
***************************************************************************/
static long
vchiq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        VCHIQ_INSTANCE_T instance = file->private_data;
        VCHIQ_STATUS_T status = VCHIQ_SUCCESS;
        VCHIQ_SERVICE_T *service = NULL;
        long ret = 0;
        int i, rc;
        DEBUG_INITIALISE(g_state.local)

        vchiq_log_trace(vchiq_arm_log_level,
                "vchiq_ioctl - instance %pK, cmd %s, arg %lx",
                instance,
                ((_IOC_TYPE(cmd) == VCHIQ_IOC_MAGIC) &&
                (_IOC_NR(cmd) <= VCHIQ_IOC_MAX)) ?
                ioctl_names[_IOC_NR(cmd)] : "<invalid>", arg);

        switch (cmd) {
        case VCHIQ_IOC_SHUTDOWN:
                if (!instance->connected)
                        break;

                /* Remove all services */
                i = 0;
                while ((service = next_service_by_instance(instance->state,
                        instance, &i)) != NULL) {
                        status = vchiq_remove_service(service->handle);
                        unlock_service(service);
                        if (status != VCHIQ_SUCCESS)
                                break;
                }
                service = NULL;

                if (status == VCHIQ_SUCCESS) {
                        /* Wake the completion thread and ask it to exit */
                        instance->closing = 1;
                        up(&instance->insert_event);
                }

                break;

        case VCHIQ_IOC_CONNECT:
                if (instance->connected) {
                        ret = -EINVAL;
                        break;
                }
                rc = mutex_lock_killable(&instance->state->mutex);
                if (rc != 0) {
                        vchiq_log_error(vchiq_arm_log_level,
                                "vchiq: connect: could not lock mutex for "
                                "state %d: %d",
                                instance->state->id, rc);
                        ret = -EINTR;
                        break;
                }
                status = vchiq_connect_internal(instance->state, instance);
                mutex_unlock(&instance->state->mutex);

                if (status == VCHIQ_SUCCESS)
                        instance->connected = 1;
                else
                        vchiq_log_error(vchiq_arm_log_level,
                                "vchiq: could not connect: %d", status);
                break;

        case VCHIQ_IOC_CREATE_SERVICE: {
                VCHIQ_CREATE_SERVICE_T args;
                USER_SERVICE_T *user_service = NULL;
                void *userdata;
                int srvstate;

                if (copy_from_user
                         (&args, (const void __user *)arg,
                          sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }

                user_service = kmalloc(sizeof(USER_SERVICE_T), GFP_KERNEL);
                if (!user_service) {
                        ret = -ENOMEM;
                        break;
                }

                if (args.is_open) {
                        if (!instance->connected) {
                                ret = -ENOTCONN;
                                kfree(user_service);
                                break;
                        }
                        srvstate = VCHIQ_SRVSTATE_OPENING;
                } else {
                        srvstate =
                                 instance->connected ?
                                 VCHIQ_SRVSTATE_LISTENING :
                                 VCHIQ_SRVSTATE_HIDDEN;
                }

                userdata = args.params.userdata;
                args.params.callback = service_callback;
                args.params.userdata = user_service;
                service = vchiq_add_service_internal(
                                instance->state,
                                &args.params, srvstate,
                                instance, user_service_free);

                if (service != NULL) {
                        user_service->service = service;
                        user_service->userdata = userdata;
                        user_service->instance = instance;
                        user_service->is_vchi = (args.is_vchi != 0);
                        user_service->dequeue_pending = 0;
                        user_service->close_pending = 0;
                        user_service->message_available_pos =
                                instance->completion_remove - 1;
                        user_service->msg_insert = 0;
                        user_service->msg_remove = 0;
                        sema_init(&user_service->insert_event, 0);
                        sema_init(&user_service->remove_event, 0);
                        sema_init(&user_service->close_event, 0);

                        if (args.is_open) {
                                status = vchiq_open_service_internal
                                        (service, instance->pid);
                                if (status != VCHIQ_SUCCESS) {
                                        vchiq_remove_service(service->handle);
                                        service = NULL;
                                        ret = (status == VCHIQ_RETRY) ?
                                                -EINTR : -EIO;
                                        break;
                                }
                        }

                        if (copy_to_user((void __user *)
                                &(((VCHIQ_CREATE_SERVICE_T __user *)
                                        arg)->handle),
                                (const void *)&service->handle,
                                sizeof(service->handle)) != 0) {
                                ret = -EFAULT;
                                vchiq_remove_service(service->handle);
                        }

                        service = NULL;
                } else {
                        ret = -EEXIST;
                        kfree(user_service);
                }
        } break;

        case VCHIQ_IOC_CLOSE_SERVICE: {
                VCHIQ_SERVICE_HANDLE_T handle = (VCHIQ_SERVICE_HANDLE_T)arg;

                service = find_service_for_instance(instance, handle);
                if (service != NULL) {
                        USER_SERVICE_T *user_service =
                                (USER_SERVICE_T *)service->base.userdata;
                        /* close_pending is false on first entry, and when the
                           wait in vchiq_close_service has been interrupted. */
                        if (!user_service->close_pending) {
                                status = vchiq_close_service(service->handle);
                                if (status != VCHIQ_SUCCESS)
                                        break;
                        }

                        /* close_pending is true once the underlying service
                           has been closed until the client library calls the
                           CLOSE_DELIVERED ioctl, signalling close_event. */
                        if (user_service->close_pending &&
                                down_interruptible(&user_service->close_event))
                                status = VCHIQ_RETRY;
                }
                else
                        ret = -EINVAL;
        } break;

        case VCHIQ_IOC_REMOVE_SERVICE: {
                VCHIQ_SERVICE_HANDLE_T handle = (VCHIQ_SERVICE_HANDLE_T)arg;

                service = find_service_for_instance(instance, handle);
                if (service != NULL) {
                        USER_SERVICE_T *user_service =
                                (USER_SERVICE_T *)service->base.userdata;
                        /* close_pending is false on first entry, and when the
                           wait in vchiq_close_service has been interrupted. */
                        if (!user_service->close_pending) {
                                status = vchiq_remove_service(service->handle);
                                if (status != VCHIQ_SUCCESS)
                                        break;
                        }

                        /* close_pending is true once the underlying service
                           has been closed until the client library calls the
                           CLOSE_DELIVERED ioctl, signalling close_event. */
                        if (user_service->close_pending &&
                                down_interruptible(&user_service->close_event))
                                status = VCHIQ_RETRY;
                }
                else
                        ret = -EINVAL;
        } break;

        case VCHIQ_IOC_USE_SERVICE:
        case VCHIQ_IOC_RELEASE_SERVICE: {
                VCHIQ_SERVICE_HANDLE_T handle = (VCHIQ_SERVICE_HANDLE_T)arg;

                service = find_service_for_instance(instance, handle);
                if (service != NULL) {
                        status = (cmd == VCHIQ_IOC_USE_SERVICE) ?
                                vchiq_use_service_internal(service) :
                                vchiq_release_service_internal(service);
                        if (status != VCHIQ_SUCCESS) {
                                vchiq_log_error(vchiq_susp_log_level,
                                        "%s: cmd %s returned error %d for "
                                        "service %c%c%c%c:%03d",
                                        __func__,
                                        (cmd == VCHIQ_IOC_USE_SERVICE) ?
                                                "VCHIQ_IOC_USE_SERVICE" :
                                                "VCHIQ_IOC_RELEASE_SERVICE",
                                        status,
                                        VCHIQ_FOURCC_AS_4CHARS(
                                                service->base.fourcc),
                                        service->client_id);
                                ret = -EINVAL;
                        }
                } else
                        ret = -EINVAL;
        } break;

        case VCHIQ_IOC_QUEUE_MESSAGE: {
                VCHIQ_QUEUE_MESSAGE_T args;
                if (copy_from_user
                         (&args, (const void __user *)arg,
                          sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }

                service = find_service_for_instance(instance, args.handle);

                if ((service != NULL) && (args.count <= MAX_ELEMENTS)) {
                        /* Copy elements into kernel space */
                        VCHIQ_ELEMENT_T elements[MAX_ELEMENTS];
                        if (copy_from_user(elements, args.elements,
                                args.count * sizeof(VCHIQ_ELEMENT_T)) == 0)
                                status = vchiq_queue_message
                                        (args.handle,
                                        elements, args.count);
                        else
                                ret = -EFAULT;
                } else {
                        ret = -EINVAL;
                }
        } break;

        case VCHIQ_IOC_QUEUE_BULK_TRANSMIT:
        case VCHIQ_IOC_QUEUE_BULK_RECEIVE: {
                VCHIQ_QUEUE_BULK_TRANSFER_T args;
                struct bulk_waiter_node *waiter = NULL;
                VCHIQ_BULK_DIR_T dir =
                        (cmd == VCHIQ_IOC_QUEUE_BULK_TRANSMIT) ?
                        VCHIQ_BULK_TRANSMIT : VCHIQ_BULK_RECEIVE;

                if (copy_from_user
                        (&args, (const void __user *)arg,
                        sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }

                service = find_service_for_instance(instance, args.handle);
                if (!service) {
                        ret = -EINVAL;
                        break;
                }

                if (args.mode == VCHIQ_BULK_MODE_BLOCKING) {
                        waiter = kzalloc(sizeof(struct bulk_waiter_node),
                                GFP_KERNEL);
                        if (!waiter) {
                                ret = -ENOMEM;
                                break;
                        }
                        args.userdata = &waiter->bulk_waiter;
                } else if (args.mode == VCHIQ_BULK_MODE_WAITING) {
                        struct list_head *pos;
                        mutex_lock(&instance->bulk_waiter_list_mutex);
                        list_for_each(pos, &instance->bulk_waiter_list) {
                                if (list_entry(pos, struct bulk_waiter_node,
                                        list)->pid == current->pid) {
                                        waiter = list_entry(pos,
                                                struct bulk_waiter_node,
                                                list);
                                        list_del(pos);
                                        break;
                                }

                        }
                        mutex_unlock(&instance->bulk_waiter_list_mutex);
                        if (!waiter) {
                                vchiq_log_error(vchiq_arm_log_level,
                                        "no bulk_waiter found for pid %d",
                                        current->pid);
                                ret = -ESRCH;
                                break;
                        }
                        vchiq_log_info(vchiq_arm_log_level,
                                "found bulk_waiter %pK for pid %d", waiter,
                                current->pid);
                        args.userdata = &waiter->bulk_waiter;
                }
                status = vchiq_bulk_transfer
                        (args.handle,
                         VCHI_MEM_HANDLE_INVALID,
                         args.data, args.size,
                         args.userdata, args.mode,
                         dir);
                if (!waiter)
                        break;
                if ((status != VCHIQ_RETRY) || fatal_signal_pending(current) ||
                        !waiter->bulk_waiter.bulk) {
                        if (waiter->bulk_waiter.bulk) {
                                /* Cancel the signal when the transfer
                                ** completes. */
                                spin_lock(&bulk_waiter_spinlock);
                                waiter->bulk_waiter.bulk->userdata = NULL;
                                spin_unlock(&bulk_waiter_spinlock);
                        }
                        kfree(waiter);
                } else {
                        const VCHIQ_BULK_MODE_T mode_waiting =
                                VCHIQ_BULK_MODE_WAITING;
                        waiter->pid = current->pid;
                        mutex_lock(&instance->bulk_waiter_list_mutex);
                        list_add(&waiter->list, &instance->bulk_waiter_list);
                        mutex_unlock(&instance->bulk_waiter_list_mutex);
                        vchiq_log_info(vchiq_arm_log_level,
                                "saved bulk_waiter %pK for pid %d",
                                waiter, current->pid);

                        if (copy_to_user((void __user *)
                                &(((VCHIQ_QUEUE_BULK_TRANSFER_T __user *)
                                        arg)->mode),
                                (const void *)&mode_waiting,
                                sizeof(mode_waiting)) != 0)
                                ret = -EFAULT;
                }
        } break;

        case VCHIQ_IOC_AWAIT_COMPLETION: {
                VCHIQ_AWAIT_COMPLETION_T args;

                DEBUG_TRACE(AWAIT_COMPLETION_LINE);
                if (!instance->connected) {
                        ret = -ENOTCONN;
                        break;
                }

                if (copy_from_user(&args, (const void __user *)arg,
                        sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }

                mutex_lock(&instance->completion_mutex);

                DEBUG_TRACE(AWAIT_COMPLETION_LINE);
                while ((instance->completion_remove ==
                        instance->completion_insert)
                        && !instance->closing) {
                        int rc;

                        DEBUG_TRACE(AWAIT_COMPLETION_LINE);
                        mutex_unlock(&instance->completion_mutex);
                        rc = down_interruptible(&instance->insert_event);
                        mutex_lock(&instance->completion_mutex);
                        if (rc != 0) {
                                DEBUG_TRACE(AWAIT_COMPLETION_LINE);
                                vchiq_log_info(vchiq_arm_log_level,
                                        "AWAIT_COMPLETION interrupted");
                                ret = -EINTR;
                                break;
                        }
                }
                DEBUG_TRACE(AWAIT_COMPLETION_LINE);

                if (ret == 0) {
                        int msgbufcount = args.msgbufcount;
                        int remove;

                        remove = instance->completion_remove;

                        for (ret = 0; ret < args.count; ret++) {
                                VCHIQ_COMPLETION_DATA_T *completion;
                                VCHIQ_SERVICE_T *service;
                                USER_SERVICE_T *user_service;
                                VCHIQ_HEADER_T *header;

                                if (remove == instance->completion_insert)
                                        break;

                                completion = &instance->completions[
                                        remove & (MAX_COMPLETIONS - 1)];


                                /* A read memory barrier is needed to prevent
                                ** the prefetch of a stale completion record
                                */
                                rmb();

                                service = completion->service_userdata;
                                user_service = service->base.userdata;
                                completion->service_userdata =
                                        user_service->userdata;

                                header = completion->header;
                                if (header) {
                                        void __user *msgbuf;
                                        int msglen;

                                        msglen = header->size +
                                                sizeof(VCHIQ_HEADER_T);
                                        /* This must be a VCHIQ-style service */
                                        if (args.msgbufsize < msglen) {
                                                vchiq_log_error(
                                                        vchiq_arm_log_level,
                                                        "header %pK: msgbufsize %x < msglen %x",
                                                        header, args.msgbufsize,
                                                        msglen);
                                                WARN(1, "invalid message "
                                                        "size\n");
                                                if (ret == 0)
                                                        ret = -EMSGSIZE;
                                                break;
                                        }
                                        if (msgbufcount <= 0)
                                                /* Stall here for lack of a
                                                ** buffer for the message. */
                                                break;
                                        /* Get the pointer from user space */
                                        msgbufcount--;
                                        if (copy_from_user(&msgbuf,
                                                (const void __user *)
                                                &args.msgbufs[msgbufcount],
                                                sizeof(msgbuf)) != 0) {
                                                if (ret == 0)
                                                        ret = -EFAULT;
                                                break;
                                        }

                                        /* Copy the message to user space */
                                        if (copy_to_user(msgbuf, header,
                                                msglen) != 0) {
                                                if (ret == 0)
                                                        ret = -EFAULT;
                                                break;
                                        }

                                        /* Now it has been copied, the message
                                        ** can be released. */
                                        vchiq_release_message(service->handle,
                                                header);

                                        /* The completion must point to the
                                        ** msgbuf. */
                                        completion->header = msgbuf;
                                }

                                if ((completion->reason ==
                                        VCHIQ_SERVICE_CLOSED) &&
                                        !instance->use_close_delivered)
                                        unlock_service(service);

                                if (copy_to_user((void __user *)(
                                        (size_t)args.buf +
                                        ret * sizeof(VCHIQ_COMPLETION_DATA_T)),
                                        completion,
                                        sizeof(VCHIQ_COMPLETION_DATA_T)) != 0) {
                                                if (ret == 0)
                                                        ret = -EFAULT;
                                        break;
                                }

                                /* Ensure that the above copy has completed
                                ** before advancing the remove pointer. */
                                mb();

                                instance->completion_remove = ++remove;
                        }

                        if (msgbufcount != args.msgbufcount) {
                                if (copy_to_user((void __user *)
                                        &((VCHIQ_AWAIT_COMPLETION_T *)arg)->
                                                msgbufcount,
                                        &msgbufcount,
                                        sizeof(msgbufcount)) != 0) {
                                        ret = -EFAULT;
                                }
                        }
                }

                if (ret != 0)
                        up(&instance->remove_event);
                mutex_unlock(&instance->completion_mutex);
                DEBUG_TRACE(AWAIT_COMPLETION_LINE);
        } break;

        case VCHIQ_IOC_DEQUEUE_MESSAGE: {
                VCHIQ_DEQUEUE_MESSAGE_T args;
                USER_SERVICE_T *user_service;
                VCHIQ_HEADER_T *header;

                DEBUG_TRACE(DEQUEUE_MESSAGE_LINE);
                if (copy_from_user
                         (&args, (const void __user *)arg,
                          sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }
                service = find_service_for_instance(instance, args.handle);
                if (!service) {
                        ret = -EINVAL;
                        break;
                }
                user_service = (USER_SERVICE_T *)service->base.userdata;
                if (user_service->is_vchi == 0) {
                        ret = -EINVAL;
                        break;
                }

                spin_lock(&msg_queue_spinlock);
                if (user_service->msg_remove == user_service->msg_insert) {
                        if (!args.blocking) {
                                spin_unlock(&msg_queue_spinlock);
                                DEBUG_TRACE(DEQUEUE_MESSAGE_LINE);
                                ret = -EWOULDBLOCK;
                                break;
                        }
                        user_service->dequeue_pending = 1;
                        do {
                                spin_unlock(&msg_queue_spinlock);
                                DEBUG_TRACE(DEQUEUE_MESSAGE_LINE);
                                if (down_interruptible(
                                        &user_service->insert_event) != 0) {
                                        vchiq_log_info(vchiq_arm_log_level,
                                                "DEQUEUE_MESSAGE interrupted");
                                        ret = -EINTR;
                                        break;
                                }
                                spin_lock(&msg_queue_spinlock);
                        } while (user_service->msg_remove ==
                                user_service->msg_insert);

                        if (ret)
                                break;
                }

                BUG_ON((int)(user_service->msg_insert -
                        user_service->msg_remove) < 0);

                header = user_service->msg_queue[user_service->msg_remove &
                        (MSG_QUEUE_SIZE - 1)];
                user_service->msg_remove++;
                spin_unlock(&msg_queue_spinlock);

                up(&user_service->remove_event);
                if (header == NULL)
                        ret = -ENOTCONN;
                else if (header->size <= args.bufsize) {
                        /* Copy to user space if msgbuf is not NULL */
                        if ((args.buf == NULL) ||
                                (copy_to_user((void __user *)args.buf,
                                header->data,
                                header->size) == 0)) {
                                ret = header->size;
                                vchiq_release_message(
                                        service->handle,
                                        header);
                        } else
                                ret = -EFAULT;
                } else {
                        vchiq_log_error(vchiq_arm_log_level,
                                "header %pK: bufsize %x < size %x",
                                header, args.bufsize, header->size);
                        WARN(1, "invalid size\n");
                        ret = -EMSGSIZE;
                }
                DEBUG_TRACE(DEQUEUE_MESSAGE_LINE);
        } break;

        case VCHIQ_IOC_GET_CLIENT_ID: {
                VCHIQ_SERVICE_HANDLE_T handle = (VCHIQ_SERVICE_HANDLE_T)arg;

                ret = vchiq_get_client_id(handle);
        } break;

        case VCHIQ_IOC_GET_CONFIG: {
                VCHIQ_GET_CONFIG_T args;
                VCHIQ_CONFIG_T config;

                if (copy_from_user(&args, (const void __user *)arg,
                        sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }
                if (args.config_size > sizeof(config)) {
                        ret = -EINVAL;
                        break;
                }
                status = vchiq_get_config(instance, args.config_size, &config);
                if (status == VCHIQ_SUCCESS) {
                        if (copy_to_user((void __user *)args.pconfig,
                                    &config, args.config_size) != 0) {
                                ret = -EFAULT;
                                break;
                        }
                }
        } break;

        case VCHIQ_IOC_SET_SERVICE_OPTION: {
                VCHIQ_SET_SERVICE_OPTION_T args;

                if (copy_from_user(
                        &args, (const void __user *)arg,
                        sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }

                service = find_service_for_instance(instance, args.handle);
                if (!service) {
                        ret = -EINVAL;
                        break;
                }

                status = vchiq_set_service_option(
                                args.handle, args.option, args.value);
        } break;

        case VCHIQ_IOC_DUMP_PHYS_MEM: {
                VCHIQ_DUMP_MEM_T  args;

                if (copy_from_user
                         (&args, (const void __user *)arg,
                          sizeof(args)) != 0) {
                        ret = -EFAULT;
                        break;
                }
                dump_phys_mem(args.virt_addr, args.num_bytes);
        } break;

        case VCHIQ_IOC_LIB_VERSION: {
                unsigned int lib_version = (unsigned int)arg;

                if (lib_version < VCHIQ_VERSION_MIN)
                        ret = -EINVAL;
                else if (lib_version >= VCHIQ_VERSION_CLOSE_DELIVERED)
                        instance->use_close_delivered = 1;
        } break;

        case VCHIQ_IOC_CLOSE_DELIVERED: {
                VCHIQ_SERVICE_HANDLE_T handle = (VCHIQ_SERVICE_HANDLE_T)arg;

                service = find_closed_service_for_instance(instance, handle);
                if (service != NULL) {
                        USER_SERVICE_T *user_service =
                                (USER_SERVICE_T *)service->base.userdata;
                        close_delivered(user_service);
                }
                else
                        ret = -EINVAL;
        } break;

        default:
                ret = -ENOTTY;
                break;
        }

        if (service)
                unlock_service(service);

        if (ret == 0) {
                if (status == VCHIQ_ERROR)
                        ret = -EIO;
                else if (status == VCHIQ_RETRY)
                        ret = -EINTR;
        }

        if ((status == VCHIQ_SUCCESS) && (ret < 0) && (ret != -EINTR) &&
                (ret != -EWOULDBLOCK))
                vchiq_log_info(vchiq_arm_log_level,
                        "  ioctl instance %lx, cmd %s -> status %d, %ld",
                        (unsigned long)instance,
                        (_IOC_NR(cmd) <= VCHIQ_IOC_MAX) ?
                                ioctl_names[_IOC_NR(cmd)] :
                                "<invalid>",
                        status, ret);
        else
                vchiq_log_trace(vchiq_arm_log_level,
                        "  ioctl instance %lx, cmd %s -> status %d, %ld",
                        (unsigned long)instance,
                        (_IOC_NR(cmd) <= VCHIQ_IOC_MAX) ?
                                ioctl_names[_IOC_NR(cmd)] :
                                "<invalid>",
                        status, ret);

        return ret;
}

/****************************************************************************
*
*   vchiq_open
*
***************************************************************************/

static int
vchiq_open(struct inode *inode, struct file *file)
{
        int dev = iminor(inode) & 0x0f;
        vchiq_log_info(vchiq_arm_log_level, "vchiq_open");
        switch (dev) {
        case VCHIQ_MINOR: {
                int ret;
                VCHIQ_STATE_T *state = vchiq_get_state();
                VCHIQ_INSTANCE_T instance;

                if (!state) {
                        vchiq_log_error(vchiq_arm_log_level,
                                "vchiq has no connection to VideoCore");
                        return -ENOTCONN;
                }

                instance = kzalloc(sizeof(*instance), GFP_KERNEL);
                if (!instance)
                        return -ENOMEM;

                instance->state = state;
                instance->pid = current->tgid;

                ret = vchiq_debugfs_add_instance(instance);
                if (ret != 0) {
                        kfree(instance);
                        return ret;
                }

                sema_init(&instance->insert_event, 0);
                sema_init(&instance->remove_event, 0);
                mutex_init(&instance->completion_mutex);
                mutex_init(&instance->bulk_waiter_list_mutex);
                INIT_LIST_HEAD(&instance->bulk_waiter_list);

                file->private_data = instance;
        } break;

        default:
                vchiq_log_error(vchiq_arm_log_level,
                        "Unknown minor device: %d", dev);
                return -ENXIO;
        }

        return 0;
}

/****************************************************************************
*
*   vchiq_release
*
***************************************************************************/

static int
vchiq_release(struct inode *inode, struct file *file)
{
        int dev = iminor(inode) & 0x0f;
        int ret = 0;
        switch (dev) {
        case VCHIQ_MINOR: {
                VCHIQ_INSTANCE_T instance = file->private_data;
                VCHIQ_STATE_T *state = vchiq_get_state();
                VCHIQ_SERVICE_T *service;
                int i;

                vchiq_log_info(vchiq_arm_log_level,
                        "vchiq_release: instance=%lx",
                        (unsigned long)instance);

                if (!state) {
                        ret = -EPERM;
                        goto out;
                }

                /* Ensure videocore is awake to allow termination. */
                vchiq_use_internal(instance->state, NULL,
                                USE_TYPE_VCHIQ);

                mutex_lock(&instance->completion_mutex);

                /* Wake the completion thread and ask it to exit */
                instance->closing = 1;
                up(&instance->insert_event);

                mutex_unlock(&instance->completion_mutex);

                /* Wake the slot handler if the completion queue is full. */
                up(&instance->remove_event);

                /* Mark all services for termination... */
                i = 0;
                while ((service = next_service_by_instance(state, instance,
                        &i)) != NULL) {
                        USER_SERVICE_T *user_service = service->base.userdata;

                        /* Wake the slot handler if the msg queue is full. */
                        up(&user_service->remove_event);

                        vchiq_terminate_service_internal(service);
                        unlock_service(service);
                }

                /* ...and wait for them to die */
                i = 0;
                while ((service = next_service_by_instance(state, instance, &i))
                        != NULL) {
                        USER_SERVICE_T *user_service = service->base.userdata;

                        down(&service->remove_event);

                        BUG_ON(service->srvstate != VCHIQ_SRVSTATE_FREE);

                        spin_lock(&msg_queue_spinlock);

                        while (user_service->msg_remove !=
                                user_service->msg_insert) {
                                VCHIQ_HEADER_T *header = user_service->
                                        msg_queue[user_service->msg_remove &
                                                (MSG_QUEUE_SIZE - 1)];
                                user_service->msg_remove++;
                                spin_unlock(&msg_queue_spinlock);

                                if (header)
                                        vchiq_release_message(
                                                service->handle,
                                                header);
                                spin_lock(&msg_queue_spinlock);
                        }

                        spin_unlock(&msg_queue_spinlock);

                        unlock_service(service);
                }

                /* Release any closed services */
                while (instance->completion_remove !=
                        instance->completion_insert) {
                        VCHIQ_COMPLETION_DATA_T *completion;
                        VCHIQ_SERVICE_T *service;
                        completion = &instance->completions[
                                instance->completion_remove &
                                (MAX_COMPLETIONS - 1)];
                        service = completion->service_userdata;
                        if (completion->reason == VCHIQ_SERVICE_CLOSED)
                        {
                                USER_SERVICE_T *user_service =
                                        service->base.userdata;

                                /* Wake any blocked user-thread */
                                if (instance->use_close_delivered)
                                        up(&user_service->close_event);
                                unlock_service(service);
                        }
                        instance->completion_remove++;
                }

                /* Release the PEER service count. */
                vchiq_release_internal(instance->state, NULL);

                {
                        struct list_head *pos, *next;
                        list_for_each_safe(pos, next,
                                &instance->bulk_waiter_list) {
                                struct bulk_waiter_node *waiter;
                                waiter = list_entry(pos,
                                        struct bulk_waiter_node,
                                        list);
                                list_del(pos);
                                vchiq_log_info(vchiq_arm_log_level,
                                        "bulk_waiter - cleaned up %pK for pid %d",
                                        waiter, waiter->pid);
                                kfree(waiter);
                        }
                }

                vchiq_debugfs_remove_instance(instance);

                kfree(instance);
                file->private_data = NULL;
        } break;

        default:
                vchiq_log_error(vchiq_arm_log_level,
                        "Unknown minor device: %d", dev);
                ret = -ENXIO;
        }

out:
        return ret;
}

/****************************************************************************
*
*   vchiq_dump
*
***************************************************************************/

void
vchiq_dump(void *dump_context, const char *str, int len)
{
        DUMP_CONTEXT_T *context = (DUMP_CONTEXT_T *)dump_context;

        if (context->actual < context->space) {
                int copy_bytes;
                if (context->offset > 0) {
                        int skip_bytes = min(len, (int)context->offset);
                        str += skip_bytes;
                        len -= skip_bytes;
                        context->offset -= skip_bytes;
                        if (context->offset > 0)
                                return;
                }
                copy_bytes = min(len, (int)(context->space - context->actual));
                if (copy_bytes == 0)
                        return;
                if (copy_to_user(context->buf + context->actual, str,
                        copy_bytes))
                        context->actual = -EFAULT;
                context->actual += copy_bytes;
                len -= copy_bytes;

                /* If tne terminating NUL is included in the length, then it
                ** marks the end of a line and should be replaced with a
                ** carriage return. */
                if ((len == 0) && (str[copy_bytes - 1] == '\0')) {
                        char cr = '\n';
                        if (copy_to_user(context->buf + context->actual - 1,
                                &cr, 1))
                                context->actual = -EFAULT;
                }
        }
}

/****************************************************************************
*
*   vchiq_dump_platform_instance_state
*
***************************************************************************/

void
vchiq_dump_platform_instances(void *dump_context)
{
        VCHIQ_STATE_T *state = vchiq_get_state();
        char buf[80];
        int len;
        int i;

        /* There is no list of instances, so instead scan all services,
                marking those that have been dumped. */

        for (i = 0; i < state->unused_service; i++) {
                VCHIQ_SERVICE_T *service = state->services[i];
                VCHIQ_INSTANCE_T instance;

                if (service && (service->base.callback == service_callback)) {
                        instance = service->instance;
                        if (instance)
                                instance->mark = 0;
                }
        }

        for (i = 0; i < state->unused_service; i++) {
                VCHIQ_SERVICE_T *service = state->services[i];
                VCHIQ_INSTANCE_T instance;

                if (service && (service->base.callback == service_callback)) {
                        instance = service->instance;
                        if (instance && !instance->mark) {
                                len = snprintf(buf, sizeof(buf),
                                        "Instance %pK: pid %d,%s completions %d/%d",
                                        instance, instance->pid,
                                        instance->connected ? " connected, " :
                                                "",
                                        instance->completion_insert -
                                                instance->completion_remove,
                                        MAX_COMPLETIONS);

                                vchiq_dump(dump_context, buf, len + 1);

                                instance->mark = 1;
                        }
                }
        }
}

/****************************************************************************
*
*   vchiq_dump_platform_service_state
*
***************************************************************************/

void
vchiq_dump_platform_service_state(void *dump_context, VCHIQ_SERVICE_T *service)
{
        USER_SERVICE_T *user_service = (USER_SERVICE_T *)service->base.userdata;
        char buf[80];
        int len;

        len = snprintf(buf, sizeof(buf), "  instance %pK", service->instance);

        if ((service->base.callback == service_callback) &&
                user_service->is_vchi) {
                len += snprintf(buf + len, sizeof(buf) - len,
                        ", %d/%d messages",
                        user_service->msg_insert - user_service->msg_remove,
                        MSG_QUEUE_SIZE);

                if (user_service->dequeue_pending)
                        len += snprintf(buf + len, sizeof(buf) - len,
                                " (dequeue pending)");
        }

        vchiq_dump(dump_context, buf, len + 1);
}

/****************************************************************************
*
*   dump_user_mem
*
***************************************************************************/

static void
dump_phys_mem(void *virt_addr, uint32_t num_bytes)
{
        int            rc;
        uint8_t       *end_virt_addr = virt_addr + num_bytes;
        int            num_pages;
        int            offset;
        int            end_offset;
        int            page_idx;
        int            prev_idx;
        struct page   *page;
        struct page  **pages;
        uint8_t       *kmapped_virt_ptr;

        /* Align virtAddr and endVirtAddr to 16 byte boundaries. */

        virt_addr = (void *)((unsigned long)virt_addr & ~0x0fuL);
        end_virt_addr = (void *)(((unsigned long)end_virt_addr + 15uL) &
                ~0x0fuL);

        offset = (int)(long)virt_addr & (PAGE_SIZE - 1);
        end_offset = (int)(long)end_virt_addr & (PAGE_SIZE - 1);

        num_pages = (offset + num_bytes + PAGE_SIZE - 1) / PAGE_SIZE;

        pages = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
        if (pages == NULL) {
                vchiq_log_error(vchiq_arm_log_level,
                        "Unable to allocation memory for %d pages\n",
                        num_pages);
                return;
        }

        down_read(&current->mm->mmap_sem);
        rc = get_user_pages(
                (unsigned long)virt_addr, /* start */
                num_pages,                /* len */
                0,                        /* gup_flags */
                pages,                    /* pages (array of page pointers) */
                NULL);                    /* vmas */
        up_read(&current->mm->mmap_sem);

        prev_idx = -1;
        page = NULL;

        if (rc < 0) {
                vchiq_log_error(vchiq_arm_log_level,
                                "Failed to get user pages: %d\n", rc);
                goto out;
        }

        while (offset < end_offset) {

                int page_offset = offset % PAGE_SIZE;
                page_idx = offset / PAGE_SIZE;

                if (page_idx != prev_idx) {

                        if (page != NULL)
                                kunmap(page);
                        page = pages[page_idx];
                        kmapped_virt_ptr = kmap(page);

                        prev_idx = page_idx;
                }

                if (vchiq_arm_log_level >= VCHIQ_LOG_TRACE)
                        vchiq_log_dump_mem("ph",
                                (uint32_t)(unsigned long)&kmapped_virt_ptr[
                                        page_offset],
                                &kmapped_virt_ptr[page_offset], 16);

                offset += 16;
        }

out:
        if (page != NULL)
                kunmap(page);

        for (page_idx = 0; page_idx < num_pages; page_idx++)
                put_page(pages[page_idx]);

        kfree(pages);
}

/****************************************************************************
*
*   vchiq_read
*
***************************************************************************/

static ssize_t
vchiq_read(struct file *file, char __user *buf,
        size_t count, loff_t *ppos)
{
        DUMP_CONTEXT_T context;
        context.buf = buf;
        context.actual = 0;
        context.space = count;
        context.offset = *ppos;

        vchiq_dump_state(&context, &g_state);

        *ppos += context.actual;

        return context.actual;
}

VCHIQ_STATE_T *
vchiq_get_state(void)
{

        if (g_state.remote == NULL)
                printk(KERN_ERR "%s: g_state.remote == NULL\n", __func__);
        else if (g_state.remote->initialised != 1)
                printk(KERN_NOTICE "%s: g_state.remote->initialised != 1 (%d)\n",
                        __func__, g_state.remote->initialised);

        return ((g_state.remote != NULL) &&
                (g_state.remote->initialised == 1)) ? &g_state : NULL;
}

static const struct file_operations
vchiq_fops = {
        .owner = THIS_MODULE,
        .unlocked_ioctl = vchiq_ioctl,
        .open = vchiq_open,
        .release = vchiq_release,
        .read = vchiq_read
};

/*
 * Autosuspend related functionality
 */

int
vchiq_videocore_wanted(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        if (!arm_state)
                /* autosuspend not supported - always return wanted */
                return 1;
        else if (arm_state->blocked_count)
                return 1;
        else if (!arm_state->videocore_use_count)
                /* usage count zero - check for override unless we're forcing */
                if (arm_state->resume_blocked)
                        return 0;
                else
                        return vchiq_platform_videocore_wanted(state);
        else
                /* non-zero usage count - videocore still required */
                return 1;
}

static VCHIQ_STATUS_T
vchiq_keepalive_vchiq_callback(VCHIQ_REASON_T reason,
        VCHIQ_HEADER_T *header,
        VCHIQ_SERVICE_HANDLE_T service_user,
        void *bulk_user)
{
        vchiq_log_error(vchiq_susp_log_level,
                "%s callback reason %d", __func__, reason);
        return 0;
}

static int
vchiq_keepalive_thread_func(void *v)
{
        VCHIQ_STATE_T *state = (VCHIQ_STATE_T *) v;
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);

        VCHIQ_STATUS_T status;
        VCHIQ_INSTANCE_T instance;
        VCHIQ_SERVICE_HANDLE_T ka_handle;

        VCHIQ_SERVICE_PARAMS_T params = {
                .fourcc      = VCHIQ_MAKE_FOURCC('K', 'E', 'E', 'P'),
                .callback    = vchiq_keepalive_vchiq_callback,
                .version     = KEEPALIVE_VER,
                .version_min = KEEPALIVE_VER_MIN
        };

        status = vchiq_initialise(&instance);
        if (status != VCHIQ_SUCCESS) {
                vchiq_log_error(vchiq_susp_log_level,
                        "%s vchiq_initialise failed %d", __func__, status);
                goto exit;
        }

        status = vchiq_connect(instance);
        if (status != VCHIQ_SUCCESS) {
                vchiq_log_error(vchiq_susp_log_level,
                        "%s vchiq_connect failed %d", __func__, status);
                goto shutdown;
        }

        status = vchiq_add_service(instance, &params, &ka_handle);
        if (status != VCHIQ_SUCCESS) {
                vchiq_log_error(vchiq_susp_log_level,
                        "%s vchiq_open_service failed %d", __func__, status);
                goto shutdown;
        }

        while (1) {
                long rc = 0, uc = 0;
                if (wait_for_completion_interruptible(&arm_state->ka_evt)
                                != 0) {
                        vchiq_log_error(vchiq_susp_log_level,
                                "%s interrupted", __func__);
                        flush_signals(current);
                        continue;
                }

                /* read and clear counters.  Do release_count then use_count to
                 * prevent getting more releases than uses */
                rc = atomic_xchg(&arm_state->ka_release_count, 0);
                uc = atomic_xchg(&arm_state->ka_use_count, 0);

                /* Call use/release service the requisite number of times.
                 * Process use before release so use counts don't go negative */
                while (uc--) {
                        atomic_inc(&arm_state->ka_use_ack_count);
                        status = vchiq_use_service(ka_handle);
                        if (status != VCHIQ_SUCCESS) {
                                vchiq_log_error(vchiq_susp_log_level,
                                        "%s vchiq_use_service error %d",
                                        __func__, status);
                        }
                }
                while (rc--) {
                        status = vchiq_release_service(ka_handle);
                        if (status != VCHIQ_SUCCESS) {
                                vchiq_log_error(vchiq_susp_log_level,
                                        "%s vchiq_release_service error %d",
                                        __func__, status);
                        }
                }
        }

shutdown:
        vchiq_shutdown(instance);
exit:
        return 0;
}



VCHIQ_STATUS_T
vchiq_arm_init_state(VCHIQ_STATE_T *state, VCHIQ_ARM_STATE_T *arm_state)
{
        if (arm_state) {
                rwlock_init(&arm_state->susp_res_lock);

                init_completion(&arm_state->ka_evt);
                atomic_set(&arm_state->ka_use_count, 0);
                atomic_set(&arm_state->ka_use_ack_count, 0);
                atomic_set(&arm_state->ka_release_count, 0);

                init_completion(&arm_state->vc_suspend_complete);

                init_completion(&arm_state->vc_resume_complete);
                /* Initialise to 'done' state.  We only want to block on resume
                 * completion while videocore is suspended. */
                set_resume_state(arm_state, VC_RESUME_RESUMED);

                init_completion(&arm_state->resume_blocker);
                /* Initialise to 'done' state.  We only want to block on this
                 * completion while resume is blocked */
                complete_all(&arm_state->resume_blocker);

                init_completion(&arm_state->blocked_blocker);
                /* Initialise to 'done' state.  We only want to block on this
                 * completion while things are waiting on the resume blocker */
                complete_all(&arm_state->blocked_blocker);

                arm_state->suspend_timer_timeout = SUSPEND_TIMER_TIMEOUT_MS;
                arm_state->suspend_timer_running = 0;
                setup_timer(&arm_state->suspend_timer, suspend_timer_callback,
                            (unsigned long)(state));

                arm_state->first_connect = 0;

        }
        return VCHIQ_SUCCESS;
}

/*
** Functions to modify the state variables;
**      set_suspend_state
**      set_resume_state
**
** There are more state variables than we might like, so ensure they remain in
** step.  Suspend and resume state are maintained separately, since most of
** these state machines can operate independently.  However, there are a few
** states where state transitions in one state machine cause a reset to the
** other state machine.  In addition, there are some completion events which
** need to occur on state machine reset and end-state(s), so these are also
** dealt with in these functions.
**
** In all states we set the state variable according to the input, but in some
** cases we perform additional steps outlined below;
**
** VC_SUSPEND_IDLE - Initialise the suspend completion at the same time.
**                      The suspend completion is completed after any suspend
**                      attempt.  When we reset the state machine we also reset
**                      the completion.  This reset occurs when videocore is
**                      resumed, and also if we initiate suspend after a suspend
**                      failure.
**
** VC_SUSPEND_IN_PROGRESS - This state is considered the point of no return for
**                      suspend - ie from this point on we must try to suspend
**                      before resuming can occur.  We therefore also reset the
**                      resume state machine to VC_RESUME_IDLE in this state.
**
** VC_SUSPEND_SUSPENDED - Suspend has completed successfully. Also call
**                      complete_all on the suspend completion to notify
**                      anything waiting for suspend to happen.
**
** VC_SUSPEND_REJECTED - Videocore rejected suspend. Videocore will also
**                      initiate resume, so no need to alter resume state.
**                      We call complete_all on the suspend completion to notify
**                      of suspend rejection.
**
** VC_SUSPEND_FAILED - We failed to initiate videocore suspend.  We notify the
**                      suspend completion and reset the resume state machine.
**
** VC_RESUME_IDLE - Initialise the resume completion at the same time.  The
**                      resume completion is in it's 'done' state whenever
**                      videcore is running.  Therefore, the VC_RESUME_IDLE
**                      state implies that videocore is suspended.
**                      Hence, any thread which needs to wait until videocore is
**                      running can wait on this completion - it will only block
**                      if videocore is suspended.
**
** VC_RESUME_RESUMED - Resume has completed successfully.  Videocore is running.
**                      Call complete_all on the resume completion to unblock
**                      any threads waiting for resume.  Also reset the suspend
**                      state machine to it's idle state.
**
** VC_RESUME_FAILED - Currently unused - no mechanism to fail resume exists.
*/

void
set_suspend_state(VCHIQ_ARM_STATE_T *arm_state,
        enum vc_suspend_status new_state)
{
        /* set the state in all cases */
        arm_state->vc_suspend_state = new_state;

        /* state specific additional actions */
        switch (new_state) {
        case VC_SUSPEND_FORCE_CANCELED:
                complete_all(&arm_state->vc_suspend_complete);
                break;
        case VC_SUSPEND_REJECTED:
                complete_all(&arm_state->vc_suspend_complete);
                break;
        case VC_SUSPEND_FAILED:
                complete_all(&arm_state->vc_suspend_complete);
                arm_state->vc_resume_state = VC_RESUME_RESUMED;
                complete_all(&arm_state->vc_resume_complete);
                break;
        case VC_SUSPEND_IDLE:
                reinit_completion(&arm_state->vc_suspend_complete);
                break;
        case VC_SUSPEND_REQUESTED:
                break;
        case VC_SUSPEND_IN_PROGRESS:
                set_resume_state(arm_state, VC_RESUME_IDLE);
                break;
        case VC_SUSPEND_SUSPENDED:
                complete_all(&arm_state->vc_suspend_complete);
                break;
        default:
                BUG();
                break;
        }
}

void
set_resume_state(VCHIQ_ARM_STATE_T *arm_state,
        enum vc_resume_status new_state)
{
        /* set the state in all cases */
        arm_state->vc_resume_state = new_state;

        /* state specific additional actions */
        switch (new_state) {
        case VC_RESUME_FAILED:
                break;
        case VC_RESUME_IDLE:
                reinit_completion(&arm_state->vc_resume_complete);
                break;
        case VC_RESUME_REQUESTED:
                break;
        case VC_RESUME_IN_PROGRESS:
                break;
        case VC_RESUME_RESUMED:
                complete_all(&arm_state->vc_resume_complete);
                set_suspend_state(arm_state, VC_SUSPEND_IDLE);
                break;
        default:
                BUG();
                break;
        }
}


/* should be called with the write lock held */
inline void
start_suspend_timer(VCHIQ_ARM_STATE_T *arm_state)
{
        del_timer(&arm_state->suspend_timer);
        arm_state->suspend_timer.expires = jiffies +
                msecs_to_jiffies(arm_state->
                        suspend_timer_timeout);
        add_timer(&arm_state->suspend_timer);
        arm_state->suspend_timer_running = 1;
}

/* should be called with the write lock held */
static inline void
stop_suspend_timer(VCHIQ_ARM_STATE_T *arm_state)
{
        if (arm_state->suspend_timer_running) {
                del_timer(&arm_state->suspend_timer);
                arm_state->suspend_timer_running = 0;
        }
}

static inline int
need_resume(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        return (arm_state->vc_suspend_state > VC_SUSPEND_IDLE) &&
                        (arm_state->vc_resume_state < VC_RESUME_REQUESTED) &&
                        vchiq_videocore_wanted(state);
}

static int
block_resume(VCHIQ_ARM_STATE_T *arm_state)
{
        int status = VCHIQ_SUCCESS;
        const unsigned long timeout_val =
                                msecs_to_jiffies(FORCE_SUSPEND_TIMEOUT_MS);
        int resume_count = 0;

        /* Allow any threads which were blocked by the last force suspend to
         * complete if they haven't already.  Only give this one shot; if
         * blocked_count is incremented after blocked_blocker is completed
         * (which only happens when blocked_count hits 0) then those threads
         * will have to wait until next time around */
        if (arm_state->blocked_count) {
                reinit_completion(&arm_state->blocked_blocker);
                write_unlock_bh(&arm_state->susp_res_lock);
                vchiq_log_info(vchiq_susp_log_level, "%s wait for previously "
                        "blocked clients", __func__);
                if (wait_for_completion_interruptible_timeout(
                                &arm_state->blocked_blocker, timeout_val)
                                        <= 0) {
                        vchiq_log_error(vchiq_susp_log_level, "%s wait for "
                                "previously blocked clients failed" , __func__);
                        status = VCHIQ_ERROR;
                        write_lock_bh(&arm_state->susp_res_lock);
                        goto out;
                }
                vchiq_log_info(vchiq_susp_log_level, "%s previously blocked "
                        "clients resumed", __func__);
                write_lock_bh(&arm_state->susp_res_lock);
        }

        /* We need to wait for resume to complete if it's in process */
        while (arm_state->vc_resume_state != VC_RESUME_RESUMED &&
                        arm_state->vc_resume_state > VC_RESUME_IDLE) {
                if (resume_count > 1) {
                        status = VCHIQ_ERROR;
                        vchiq_log_error(vchiq_susp_log_level, "%s waited too "
                                "many times for resume" , __func__);
                        goto out;
                }
                write_unlock_bh(&arm_state->susp_res_lock);
                vchiq_log_info(vchiq_susp_log_level, "%s wait for resume",
                        __func__);
                if (wait_for_completion_interruptible_timeout(
                                &arm_state->vc_resume_complete, timeout_val)
                                        <= 0) {
                        vchiq_log_error(vchiq_susp_log_level, "%s wait for "
                                "resume failed (%s)", __func__,
                                resume_state_names[arm_state->vc_resume_state +
                                                        VC_RESUME_NUM_OFFSET]);
                        status = VCHIQ_ERROR;
                        write_lock_bh(&arm_state->susp_res_lock);
                        goto out;
                }
                vchiq_log_info(vchiq_susp_log_level, "%s resumed", __func__);
                write_lock_bh(&arm_state->susp_res_lock);
                resume_count++;
        }
        reinit_completion(&arm_state->resume_blocker);
        arm_state->resume_blocked = 1;

out:
        return status;
}

static inline void
unblock_resume(VCHIQ_ARM_STATE_T *arm_state)
{
        complete_all(&arm_state->resume_blocker);
        arm_state->resume_blocked = 0;
}

/* Initiate suspend via slot handler. Should be called with the write lock
 * held */
VCHIQ_STATUS_T
vchiq_arm_vcsuspend(VCHIQ_STATE_T *state)
{
        VCHIQ_STATUS_T status = VCHIQ_ERROR;
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);
        status = VCHIQ_SUCCESS;


        switch (arm_state->vc_suspend_state) {
        case VC_SUSPEND_REQUESTED:
                vchiq_log_info(vchiq_susp_log_level, "%s: suspend already "
                        "requested", __func__);
                break;
        case VC_SUSPEND_IN_PROGRESS:
                vchiq_log_info(vchiq_susp_log_level, "%s: suspend already in "
                        "progress", __func__);
                break;

        default:
                /* We don't expect to be in other states, so log but continue
                 * anyway */
                vchiq_log_error(vchiq_susp_log_level,
                        "%s unexpected suspend state %s", __func__,
                        suspend_state_names[arm_state->vc_suspend_state +
                                                VC_SUSPEND_NUM_OFFSET]);
                /* fall through */
        case VC_SUSPEND_REJECTED:
        case VC_SUSPEND_FAILED:
                /* Ensure any idle state actions have been run */
                set_suspend_state(arm_state, VC_SUSPEND_IDLE);
                /* fall through */
        case VC_SUSPEND_IDLE:
                vchiq_log_info(vchiq_susp_log_level,
                        "%s: suspending", __func__);
                set_suspend_state(arm_state, VC_SUSPEND_REQUESTED);
                /* kick the slot handler thread to initiate suspend */
                request_poll(state, NULL, 0);
                break;
        }

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit %d", __func__, status);
        return status;
}

void
vchiq_platform_check_suspend(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        int susp = 0;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        write_lock_bh(&arm_state->susp_res_lock);
        if (arm_state->vc_suspend_state == VC_SUSPEND_REQUESTED &&
                        arm_state->vc_resume_state == VC_RESUME_RESUMED) {
                set_suspend_state(arm_state, VC_SUSPEND_IN_PROGRESS);
                susp = 1;
        }
        write_unlock_bh(&arm_state->susp_res_lock);

        if (susp)
                vchiq_platform_suspend(state);

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit", __func__);
        return;
}


static void
output_timeout_error(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        char err[50] = "";
        int vc_use_count = arm_state->videocore_use_count;
        int active_services = state->unused_service;
        int i;

        if (!arm_state->videocore_use_count) {
                snprintf(err, sizeof(err), " Videocore usecount is 0");
                goto output_msg;
        }
        for (i = 0; i < active_services; i++) {
                VCHIQ_SERVICE_T *service_ptr = state->services[i];
                if (service_ptr && service_ptr->service_use_count &&
                        (service_ptr->srvstate != VCHIQ_SRVSTATE_FREE)) {
                        snprintf(err, sizeof(err), " %c%c%c%c(%d) service has "
                                "use count %d%s", VCHIQ_FOURCC_AS_4CHARS(
                                        service_ptr->base.fourcc),
                                 service_ptr->client_id,
                                 service_ptr->service_use_count,
                                 service_ptr->service_use_count ==
                                         vc_use_count ? "" : " (+ more)");
                        break;
                }
        }

output_msg:
        vchiq_log_error(vchiq_susp_log_level,
                "timed out waiting for vc suspend (%d).%s",
                 arm_state->autosuspend_override, err);

}

/* Try to get videocore into suspended state, regardless of autosuspend state.
** We don't actually force suspend, since videocore may get into a bad state
** if we force suspend at a bad time.  Instead, we wait for autosuspend to
** determine a good point to suspend.  If this doesn't happen within 100ms we
** report failure.
**
** Returns VCHIQ_SUCCESS if videocore suspended successfully, VCHIQ_RETRY if
** videocore failed to suspend in time or VCHIQ_ERROR if interrupted.
*/
VCHIQ_STATUS_T
vchiq_arm_force_suspend(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        VCHIQ_STATUS_T status = VCHIQ_ERROR;
        long rc = 0;
        int repeat = -1;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        write_lock_bh(&arm_state->susp_res_lock);

        status = block_resume(arm_state);
        if (status != VCHIQ_SUCCESS)
                goto unlock;
        if (arm_state->vc_suspend_state == VC_SUSPEND_SUSPENDED) {
                /* Already suspended - just block resume and exit */
                vchiq_log_info(vchiq_susp_log_level, "%s already suspended",
                        __func__);
                status = VCHIQ_SUCCESS;
                goto unlock;
        } else if (arm_state->vc_suspend_state <= VC_SUSPEND_IDLE) {
                /* initiate suspend immediately in the case that we're waiting
                 * for the timeout */
                stop_suspend_timer(arm_state);
                if (!vchiq_videocore_wanted(state)) {
                        vchiq_log_info(vchiq_susp_log_level, "%s videocore "
                                "idle, initiating suspend", __func__);
                        status = vchiq_arm_vcsuspend(state);
                } else if (arm_state->autosuspend_override <
                                                FORCE_SUSPEND_FAIL_MAX) {
                        vchiq_log_info(vchiq_susp_log_level, "%s letting "
                                "videocore go idle", __func__);
                        status = VCHIQ_SUCCESS;
                } else {
                        vchiq_log_warning(vchiq_susp_log_level, "%s failed too "
                                "many times - attempting suspend", __func__);
                        status = vchiq_arm_vcsuspend(state);
                }
        } else {
                vchiq_log_info(vchiq_susp_log_level, "%s videocore suspend "
                        "in progress - wait for completion", __func__);
                status = VCHIQ_SUCCESS;
        }

        /* Wait for suspend to happen due to system idle (not forced..) */
        if (status != VCHIQ_SUCCESS)
                goto unblock_resume;

        do {
                write_unlock_bh(&arm_state->susp_res_lock);

                rc = wait_for_completion_interruptible_timeout(
                                &arm_state->vc_suspend_complete,
                                msecs_to_jiffies(FORCE_SUSPEND_TIMEOUT_MS));

                write_lock_bh(&arm_state->susp_res_lock);
                if (rc < 0) {
                        vchiq_log_warning(vchiq_susp_log_level, "%s "
                                "interrupted waiting for suspend", __func__);
                        status = VCHIQ_ERROR;
                        goto unblock_resume;
                } else if (rc == 0) {
                        if (arm_state->vc_suspend_state > VC_SUSPEND_IDLE) {
                                /* Repeat timeout once if in progress */
                                if (repeat < 0) {
                                        repeat = 1;
                                        continue;
                                }
                        }
                        arm_state->autosuspend_override++;
                        output_timeout_error(state);

                        status = VCHIQ_RETRY;
                        goto unblock_resume;
                }
        } while (0 < (repeat--));

        /* Check and report state in case we need to abort ARM suspend */
        if (arm_state->vc_suspend_state != VC_SUSPEND_SUSPENDED) {
                status = VCHIQ_RETRY;
                vchiq_log_error(vchiq_susp_log_level,
                        "%s videocore suspend failed (state %s)", __func__,
                        suspend_state_names[arm_state->vc_suspend_state +
                                                VC_SUSPEND_NUM_OFFSET]);
                /* Reset the state only if it's still in an error state.
                 * Something could have already initiated another suspend. */
                if (arm_state->vc_suspend_state < VC_SUSPEND_IDLE)
                        set_suspend_state(arm_state, VC_SUSPEND_IDLE);

                goto unblock_resume;
        }

        /* successfully suspended - unlock and exit */
        goto unlock;

unblock_resume:
        /* all error states need to unblock resume before exit */
        unblock_resume(arm_state);

unlock:
        write_unlock_bh(&arm_state->susp_res_lock);

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit %d", __func__, status);
        return status;
}

void
vchiq_check_suspend(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        write_lock_bh(&arm_state->susp_res_lock);
        if (arm_state->vc_suspend_state != VC_SUSPEND_SUSPENDED &&
                        arm_state->first_connect &&
                        !vchiq_videocore_wanted(state)) {
                vchiq_arm_vcsuspend(state);
        }
        write_unlock_bh(&arm_state->susp_res_lock);

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit", __func__);
        return;
}


int
vchiq_arm_allow_resume(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        int resume = 0;
        int ret = -1;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        write_lock_bh(&arm_state->susp_res_lock);
        unblock_resume(arm_state);
        resume = vchiq_check_resume(state);
        write_unlock_bh(&arm_state->susp_res_lock);

        if (resume) {
                if (wait_for_completion_interruptible(
                        &arm_state->vc_resume_complete) < 0) {
                        vchiq_log_error(vchiq_susp_log_level,
                                "%s interrupted", __func__);
                        /* failed, cannot accurately derive suspend
                         * state, so exit early. */
                        goto out;
                }
        }

        read_lock_bh(&arm_state->susp_res_lock);
        if (arm_state->vc_suspend_state == VC_SUSPEND_SUSPENDED) {
                vchiq_log_info(vchiq_susp_log_level,
                                "%s: Videocore remains suspended", __func__);
        } else {
                vchiq_log_info(vchiq_susp_log_level,
                                "%s: Videocore resumed", __func__);
                ret = 0;
        }
        read_unlock_bh(&arm_state->susp_res_lock);
out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit %d", __func__, ret);
        return ret;
}

/* This function should be called with the write lock held */
int
vchiq_check_resume(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        int resume = 0;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        if (need_resume(state)) {
                set_resume_state(arm_state, VC_RESUME_REQUESTED);
                request_poll(state, NULL, 0);
                resume = 1;
        }

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit", __func__);
        return resume;
}

void
vchiq_platform_check_resume(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        int res = 0;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        write_lock_bh(&arm_state->susp_res_lock);
        if (arm_state->wake_address == 0) {
                vchiq_log_info(vchiq_susp_log_level,
                                        "%s: already awake", __func__);
                goto unlock;
        }
        if (arm_state->vc_resume_state == VC_RESUME_IN_PROGRESS) {
                vchiq_log_info(vchiq_susp_log_level,
                                        "%s: already resuming", __func__);
                goto unlock;
        }

        if (arm_state->vc_resume_state == VC_RESUME_REQUESTED) {
                set_resume_state(arm_state, VC_RESUME_IN_PROGRESS);
                res = 1;
        } else
                vchiq_log_trace(vchiq_susp_log_level,
                                "%s: not resuming (resume state %s)", __func__,
                                resume_state_names[arm_state->vc_resume_state +
                                                        VC_RESUME_NUM_OFFSET]);

unlock:
        write_unlock_bh(&arm_state->susp_res_lock);

        if (res)
                vchiq_platform_resume(state);

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit", __func__);
        return;

}



VCHIQ_STATUS_T
vchiq_use_internal(VCHIQ_STATE_T *state, VCHIQ_SERVICE_T *service,
                enum USE_TYPE_E use_type)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        VCHIQ_STATUS_T ret = VCHIQ_SUCCESS;
        char entity[16];
        int *entity_uc;
        int local_uc, local_entity_uc;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        if (use_type == USE_TYPE_VCHIQ) {
                sprintf(entity, "VCHIQ:   ");
                entity_uc = &arm_state->peer_use_count;
        } else if (service) {
                sprintf(entity, "%c%c%c%c:%03d",
                        VCHIQ_FOURCC_AS_4CHARS(service->base.fourcc),
                        service->client_id);
                entity_uc = &service->service_use_count;
        } else {
                vchiq_log_error(vchiq_susp_log_level, "%s null service "
                                "ptr", __func__);
                ret = VCHIQ_ERROR;
                goto out;
        }

        write_lock_bh(&arm_state->susp_res_lock);
        while (arm_state->resume_blocked) {
                /* If we call 'use' while force suspend is waiting for suspend,
                 * then we're about to block the thread which the force is
                 * waiting to complete, so we're bound to just time out. In this
                 * case, set the suspend state such that the wait will be
                 * canceled, so we can complete as quickly as possible. */
                if (arm_state->resume_blocked && arm_state->vc_suspend_state ==
                                VC_SUSPEND_IDLE) {
                        set_suspend_state(arm_state, VC_SUSPEND_FORCE_CANCELED);
                        break;
                }
                /* If suspend is already in progress then we need to block */
                if (!try_wait_for_completion(&arm_state->resume_blocker)) {
                        /* Indicate that there are threads waiting on the resume
                         * blocker.  These need to be allowed to complete before
                         * a _second_ call to force suspend can complete,
                         * otherwise low priority threads might never actually
                         * continue */
                        arm_state->blocked_count++;
                        write_unlock_bh(&arm_state->susp_res_lock);
                        vchiq_log_info(vchiq_susp_log_level, "%s %s resume "
                                "blocked - waiting...", __func__, entity);
                        if (wait_for_completion_killable(
                                        &arm_state->resume_blocker) != 0) {
                                vchiq_log_error(vchiq_susp_log_level, "%s %s "
                                        "wait for resume blocker interrupted",
                                        __func__, entity);
                                ret = VCHIQ_ERROR;
                                write_lock_bh(&arm_state->susp_res_lock);
                                arm_state->blocked_count--;
                                write_unlock_bh(&arm_state->susp_res_lock);
                                goto out;
                        }
                        vchiq_log_info(vchiq_susp_log_level, "%s %s resume "
                                "unblocked", __func__, entity);
                        write_lock_bh(&arm_state->susp_res_lock);
                        if (--arm_state->blocked_count == 0)
                                complete_all(&arm_state->blocked_blocker);
                }
        }

        stop_suspend_timer(arm_state);

        local_uc = ++arm_state->videocore_use_count;
        local_entity_uc = ++(*entity_uc);

        /* If there's a pending request which hasn't yet been serviced then
         * just clear it.  If we're past VC_SUSPEND_REQUESTED state then
         * vc_resume_complete will block until we either resume or fail to
         * suspend */
        if (arm_state->vc_suspend_state <= VC_SUSPEND_REQUESTED)
                set_suspend_state(arm_state, VC_SUSPEND_IDLE);

        if ((use_type != USE_TYPE_SERVICE_NO_RESUME) && need_resume(state)) {
                set_resume_state(arm_state, VC_RESUME_REQUESTED);
                vchiq_log_info(vchiq_susp_log_level,
                        "%s %s count %d, state count %d",
                        __func__, entity, local_entity_uc, local_uc);
                request_poll(state, NULL, 0);
        } else
                vchiq_log_trace(vchiq_susp_log_level,
                        "%s %s count %d, state count %d",
                        __func__, entity, *entity_uc, local_uc);


        write_unlock_bh(&arm_state->susp_res_lock);

        /* Completion is in a done state when we're not suspended, so this won't
         * block for the non-suspended case. */
        if (!try_wait_for_completion(&arm_state->vc_resume_complete)) {
                vchiq_log_info(vchiq_susp_log_level, "%s %s wait for resume",
                        __func__, entity);
                if (wait_for_completion_killable(
                                &arm_state->vc_resume_complete) != 0) {
                        vchiq_log_error(vchiq_susp_log_level, "%s %s wait for "
                                "resume interrupted", __func__, entity);
                        ret = VCHIQ_ERROR;
                        goto out;
                }
                vchiq_log_info(vchiq_susp_log_level, "%s %s resumed", __func__,
                        entity);
        }

        if (ret == VCHIQ_SUCCESS) {
                VCHIQ_STATUS_T status = VCHIQ_SUCCESS;
                long ack_cnt = atomic_xchg(&arm_state->ka_use_ack_count, 0);
                while (ack_cnt && (status == VCHIQ_SUCCESS)) {
                        /* Send the use notify to videocore */
                        status = vchiq_send_remote_use_active(state);
                        if (status == VCHIQ_SUCCESS)
                                ack_cnt--;
                        else
                                atomic_add(ack_cnt,
                                        &arm_state->ka_use_ack_count);
                }
        }

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit %d", __func__, ret);
        return ret;
}

VCHIQ_STATUS_T
vchiq_release_internal(VCHIQ_STATE_T *state, VCHIQ_SERVICE_T *service)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        VCHIQ_STATUS_T ret = VCHIQ_SUCCESS;
        char entity[16];
        int *entity_uc;
        int local_uc, local_entity_uc;

        if (!arm_state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        if (service) {
                sprintf(entity, "%c%c%c%c:%03d",
                        VCHIQ_FOURCC_AS_4CHARS(service->base.fourcc),
                        service->client_id);
                entity_uc = &service->service_use_count;
        } else {
                sprintf(entity, "PEER:   ");
                entity_uc = &arm_state->peer_use_count;
        }

        write_lock_bh(&arm_state->susp_res_lock);
        if (!arm_state->videocore_use_count || !(*entity_uc)) {
                /* Don't use BUG_ON - don't allow user thread to crash kernel */
                WARN_ON(!arm_state->videocore_use_count);
                WARN_ON(!(*entity_uc));
                ret = VCHIQ_ERROR;
                goto unlock;
        }
        local_uc = --arm_state->videocore_use_count;
        local_entity_uc = --(*entity_uc);

        if (!vchiq_videocore_wanted(state)) {
                if (vchiq_platform_use_suspend_timer() &&
                                !arm_state->resume_blocked) {
                        /* Only use the timer if we're not trying to force
                         * suspend (=> resume_blocked) */
                        start_suspend_timer(arm_state);
                } else {
                        vchiq_log_info(vchiq_susp_log_level,
                                "%s %s count %d, state count %d - suspending",
                                __func__, entity, *entity_uc,
                                arm_state->videocore_use_count);
                        vchiq_arm_vcsuspend(state);
                }
        } else
                vchiq_log_trace(vchiq_susp_log_level,
                        "%s %s count %d, state count %d",
                        __func__, entity, *entity_uc,
                        arm_state->videocore_use_count);

unlock:
        write_unlock_bh(&arm_state->susp_res_lock);

out:
        vchiq_log_trace(vchiq_susp_log_level, "%s exit %d", __func__, ret);
        return ret;
}

void
vchiq_on_remote_use(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);
        atomic_inc(&arm_state->ka_use_count);
        complete(&arm_state->ka_evt);
}

void
vchiq_on_remote_release(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);
        atomic_inc(&arm_state->ka_release_count);
        complete(&arm_state->ka_evt);
}

VCHIQ_STATUS_T
vchiq_use_service_internal(VCHIQ_SERVICE_T *service)
{
        return vchiq_use_internal(service->state, service, USE_TYPE_SERVICE);
}

VCHIQ_STATUS_T
vchiq_release_service_internal(VCHIQ_SERVICE_T *service)
{
        return vchiq_release_internal(service->state, service);
}

VCHIQ_DEBUGFS_NODE_T *
vchiq_instance_get_debugfs_node(VCHIQ_INSTANCE_T instance)
{
        return &instance->debugfs_node;
}

int
vchiq_instance_get_use_count(VCHIQ_INSTANCE_T instance)
{
        VCHIQ_SERVICE_T *service;
        int use_count = 0, i;
        i = 0;
        while ((service = next_service_by_instance(instance->state,
                instance, &i)) != NULL) {
                use_count += service->service_use_count;
                unlock_service(service);
        }
        return use_count;
}

int
vchiq_instance_get_pid(VCHIQ_INSTANCE_T instance)
{
        return instance->pid;
}

int
vchiq_instance_get_trace(VCHIQ_INSTANCE_T instance)
{
        return instance->trace;
}

void
vchiq_instance_set_trace(VCHIQ_INSTANCE_T instance, int trace)
{
        VCHIQ_SERVICE_T *service;
        int i;
        i = 0;
        while ((service = next_service_by_instance(instance->state,
                instance, &i)) != NULL) {
                service->trace = trace;
                unlock_service(service);
        }
        instance->trace = (trace != 0);
}

static void suspend_timer_callback(unsigned long context)
{
        VCHIQ_STATE_T *state = (VCHIQ_STATE_T *)context;
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        if (!arm_state)
                goto out;
        vchiq_log_info(vchiq_susp_log_level,
                "%s - suspend timer expired - check suspend", __func__);
        vchiq_check_suspend(state);
out:
        return;
}

VCHIQ_STATUS_T
vchiq_use_service_no_resume(VCHIQ_SERVICE_HANDLE_T handle)
{
        VCHIQ_STATUS_T ret = VCHIQ_ERROR;
        VCHIQ_SERVICE_T *service = find_service_by_handle(handle);
        if (service) {
                ret = vchiq_use_internal(service->state, service,
                                USE_TYPE_SERVICE_NO_RESUME);
                unlock_service(service);
        }
        return ret;
}

VCHIQ_STATUS_T
vchiq_use_service(VCHIQ_SERVICE_HANDLE_T handle)
{
        VCHIQ_STATUS_T ret = VCHIQ_ERROR;
        VCHIQ_SERVICE_T *service = find_service_by_handle(handle);
        if (service) {
                ret = vchiq_use_internal(service->state, service,
                                USE_TYPE_SERVICE);
                unlock_service(service);
        }
        return ret;
}

VCHIQ_STATUS_T
vchiq_release_service(VCHIQ_SERVICE_HANDLE_T handle)
{
        VCHIQ_STATUS_T ret = VCHIQ_ERROR;
        VCHIQ_SERVICE_T *service = find_service_by_handle(handle);
        if (service) {
                ret = vchiq_release_internal(service->state, service);
                unlock_service(service);
        }
        return ret;
}

void
vchiq_dump_service_use_state(VCHIQ_STATE_T *state)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        int i, j = 0;
        /* Only dump 64 services */
        static const int local_max_services = 64;
        /* If there's more than 64 services, only dump ones with
         * non-zero counts */
        int only_nonzero = 0;
        static const char *nz = "<-- preventing suspend";

        enum vc_suspend_status vc_suspend_state;
        enum vc_resume_status  vc_resume_state;
        int peer_count;
        int vc_use_count;
        int active_services;
        struct service_data_struct {
                int fourcc;
                int clientid;
                int use_count;
        } service_data[local_max_services];

        if (!arm_state)
                return;

        read_lock_bh(&arm_state->susp_res_lock);
        vc_suspend_state = arm_state->vc_suspend_state;
        vc_resume_state  = arm_state->vc_resume_state;
        peer_count = arm_state->peer_use_count;
        vc_use_count = arm_state->videocore_use_count;
        active_services = state->unused_service;
        if (active_services > local_max_services)
                only_nonzero = 1;

        for (i = 0; (i < active_services) && (j < local_max_services); i++) {
                VCHIQ_SERVICE_T *service_ptr = state->services[i];
                if (!service_ptr)
                        continue;

                if (only_nonzero && !service_ptr->service_use_count)
                        continue;

                if (service_ptr->srvstate != VCHIQ_SRVSTATE_FREE) {
                        service_data[j].fourcc = service_ptr->base.fourcc;
                        service_data[j].clientid = service_ptr->client_id;
                        service_data[j++].use_count = service_ptr->
                                                        service_use_count;
                }
        }

        read_unlock_bh(&arm_state->susp_res_lock);

        vchiq_log_warning(vchiq_susp_log_level,
                "-- Videcore suspend state: %s --",
                suspend_state_names[vc_suspend_state + VC_SUSPEND_NUM_OFFSET]);
        vchiq_log_warning(vchiq_susp_log_level,
                "-- Videcore resume state: %s --",
                resume_state_names[vc_resume_state + VC_RESUME_NUM_OFFSET]);

        if (only_nonzero)
                vchiq_log_warning(vchiq_susp_log_level, "Too many active "
                        "services (%d).  Only dumping up to first %d services "
                        "with non-zero use-count", active_services,
                        local_max_services);

        for (i = 0; i < j; i++) {
                vchiq_log_warning(vchiq_susp_log_level,
                        "----- %c%c%c%c:%d service count %d %s",
                        VCHIQ_FOURCC_AS_4CHARS(service_data[i].fourcc),
                        service_data[i].clientid,
                        service_data[i].use_count,
                        service_data[i].use_count ? nz : "");
        }
        vchiq_log_warning(vchiq_susp_log_level,
                "----- VCHIQ use count count %d", peer_count);
        vchiq_log_warning(vchiq_susp_log_level,
                "--- Overall vchiq instance use count %d", vc_use_count);

        vchiq_dump_platform_use_state(state);
}

VCHIQ_STATUS_T
vchiq_check_service(VCHIQ_SERVICE_T *service)
{
        VCHIQ_ARM_STATE_T *arm_state;
        VCHIQ_STATUS_T ret = VCHIQ_ERROR;

        if (!service || !service->state)
                goto out;

        vchiq_log_trace(vchiq_susp_log_level, "%s", __func__);

        arm_state = vchiq_platform_get_arm_state(service->state);

        read_lock_bh(&arm_state->susp_res_lock);
        if (service->service_use_count)
                ret = VCHIQ_SUCCESS;
        read_unlock_bh(&arm_state->susp_res_lock);

        if (ret == VCHIQ_ERROR) {
                vchiq_log_error(vchiq_susp_log_level,
                        "%s ERROR - %c%c%c%c:%d service count %d, "
                        "state count %d, videocore suspend state %s", __func__,
                        VCHIQ_FOURCC_AS_4CHARS(service->base.fourcc),
                        service->client_id, service->service_use_count,
                        arm_state->videocore_use_count,
                        suspend_state_names[arm_state->vc_suspend_state +
                                                VC_SUSPEND_NUM_OFFSET]);
                vchiq_dump_service_use_state(service->state);
        }
out:
        return ret;
}

/* stub functions */
void vchiq_on_remote_use_active(VCHIQ_STATE_T *state)
{
        (void)state;
}

void vchiq_platform_conn_state_changed(VCHIQ_STATE_T *state,
        VCHIQ_CONNSTATE_T oldstate, VCHIQ_CONNSTATE_T newstate)
{
        VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
        vchiq_log_info(vchiq_susp_log_level, "%d: %s->%s", state->id,
                get_conn_state_name(oldstate), get_conn_state_name(newstate));
        if (state->conn_state == VCHIQ_CONNSTATE_CONNECTED) {
                write_lock_bh(&arm_state->susp_res_lock);
                if (!arm_state->first_connect) {
                        char threadname[10];
                        arm_state->first_connect = 1;
                        write_unlock_bh(&arm_state->susp_res_lock);
                        snprintf(threadname, sizeof(threadname), "VCHIQka-%d",
                                state->id);
                        arm_state->ka_thread = kthread_create(
                                &vchiq_keepalive_thread_func,
                                (void *)state,
                                threadname);
                        if (IS_ERR(arm_state->ka_thread)) {
                                vchiq_log_error(vchiq_susp_log_level,
                                        "vchiq: FATAL: couldn't create thread %s",
                                        threadname);
                        } else {
                                wake_up_process(arm_state->ka_thread);
                        }
                } else
                        write_unlock_bh(&arm_state->susp_res_lock);
        }
}

static int vchiq_probe(struct platform_device *pdev)
{
        struct device_node *fw_node;
        struct rpi_firmware *fw;
        int err;
        void *ptr_err;

        fw_node = of_parse_phandle(pdev->dev.of_node, "firmware", 0);
        if (!fw_node) {
                dev_err(&pdev->dev, "Missing firmware node\n");
                return -ENOENT;
        }

        fw = rpi_firmware_get(fw_node);
        of_node_put(fw_node);
        if (!fw)
                return -EPROBE_DEFER;

        platform_set_drvdata(pdev, fw);

        err = vchiq_platform_init(pdev, &g_state);
        if (err != 0)
                goto failed_platform_init;

        err = alloc_chrdev_region(&vchiq_devid, VCHIQ_MINOR, 1, DEVICE_NAME);
        if (err != 0) {
                vchiq_log_error(vchiq_arm_log_level,
                        "Unable to allocate device number");
                goto failed_platform_init;
        }
        cdev_init(&vchiq_cdev, &vchiq_fops);
        vchiq_cdev.owner = THIS_MODULE;
        err = cdev_add(&vchiq_cdev, vchiq_devid, 1);
        if (err != 0) {
                vchiq_log_error(vchiq_arm_log_level,
                        "Unable to register device");
                goto failed_cdev_add;
        }

        /* create sysfs entries */
        vchiq_class = class_create(THIS_MODULE, DEVICE_NAME);
        ptr_err = vchiq_class;
        if (IS_ERR(ptr_err))
                goto failed_class_create;

        vchiq_dev = device_create(vchiq_class, NULL,
                vchiq_devid, NULL, "vchiq");
        ptr_err = vchiq_dev;
        if (IS_ERR(ptr_err))
                goto failed_device_create;

        /* create debugfs entries */
        err = vchiq_debugfs_init();
        if (err != 0)
                goto failed_debugfs_init;

        vchiq_log_info(vchiq_arm_log_level,
                "vchiq: initialised - version %d (min %d), device %d.%d",
                VCHIQ_VERSION, VCHIQ_VERSION_MIN,
                MAJOR(vchiq_devid), MINOR(vchiq_devid));

        return 0;

failed_debugfs_init:
        device_destroy(vchiq_class, vchiq_devid);
failed_device_create:
        class_destroy(vchiq_class);
failed_class_create:
        cdev_del(&vchiq_cdev);
        err = PTR_ERR(ptr_err);
failed_cdev_add:
        unregister_chrdev_region(vchiq_devid, 1);
failed_platform_init:
        vchiq_log_warning(vchiq_arm_log_level, "could not load vchiq");
        return err;
}

static int vchiq_remove(struct platform_device *pdev)
{
        vchiq_debugfs_deinit();
        device_destroy(vchiq_class, vchiq_devid);
        class_destroy(vchiq_class);
        cdev_del(&vchiq_cdev);
        unregister_chrdev_region(vchiq_devid, 1);

        return 0;
}

static const struct of_device_id vchiq_of_match[] = {
        { .compatible = "brcm,bcm2835-vchiq", },
        {},
};
MODULE_DEVICE_TABLE(of, vchiq_of_match);

static struct platform_driver vchiq_driver = {
        .driver = {
                .name = "bcm2835_vchiq",
                .of_match_table = vchiq_of_match,
        },
        .probe = vchiq_probe,
        .remove = vchiq_remove,
};
module_platform_driver(vchiq_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Videocore VCHIQ driver");
MODULE_AUTHOR("Broadcom Corporation");