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[mirror_ubuntu-bionic-kernel.git] / arch / powerpc / platforms / powernv / opal.c

/*
 * PowerNV OPAL high level interfaces
 *
 * Copyright 2011 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#define pr_fmt(fmt)     "opal: " fmt

#include <linux/printk.h>
#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_platform.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kobject.h>
#include <linux/delay.h>
#include <linux/memblock.h>
#include <linux/kthread.h>
#include <linux/freezer.h>

#include <asm/machdep.h>
#include <asm/opal.h>
#include <asm/firmware.h>
#include <asm/mce.h>

#include "powernv.h"

/* /sys/firmware/opal */
struct kobject *opal_kobj;

struct opal {
        u64 base;
        u64 entry;
        u64 size;
} opal;

struct mcheck_recoverable_range {
        u64 start_addr;
        u64 end_addr;
        u64 recover_addr;
};

static struct mcheck_recoverable_range *mc_recoverable_range;
static int mc_recoverable_range_len;

struct device_node *opal_node;
static DEFINE_SPINLOCK(opal_write_lock);
static struct atomic_notifier_head opal_msg_notifier_head[OPAL_MSG_TYPE_MAX];
static uint32_t opal_heartbeat;
static struct task_struct *kopald_tsk;

void opal_configure_cores(void)
{
        /* Do the actual re-init, This will clobber all FPRs, VRs, etc...
         *
         * It will preserve non volatile GPRs and HSPRG0/1. It will
         * also restore HIDs and other SPRs to their original value
         * but it might clobber a bunch.
         */
#ifdef __BIG_ENDIAN__
        opal_reinit_cpus(OPAL_REINIT_CPUS_HILE_BE);
#else
        opal_reinit_cpus(OPAL_REINIT_CPUS_HILE_LE);
#endif

        /* Restore some bits */
        if (cur_cpu_spec->cpu_restore)
                cur_cpu_spec->cpu_restore();
}

int __init early_init_dt_scan_opal(unsigned long node,
                                   const char *uname, int depth, void *data)
{
        const void *basep, *entryp, *sizep;
        int basesz, entrysz, runtimesz;

        if (depth != 1 || strcmp(uname, "ibm,opal") != 0)
                return 0;

        basep  = of_get_flat_dt_prop(node, "opal-base-address", &basesz);
        entryp = of_get_flat_dt_prop(node, "opal-entry-address", &entrysz);
        sizep = of_get_flat_dt_prop(node, "opal-runtime-size", &runtimesz);

        if (!basep || !entryp || !sizep)
                return 1;

        opal.base = of_read_number(basep, basesz/4);
        opal.entry = of_read_number(entryp, entrysz/4);
        opal.size = of_read_number(sizep, runtimesz/4);

        pr_debug("OPAL Base  = 0x%llx (basep=%p basesz=%d)\n",
                 opal.base, basep, basesz);
        pr_debug("OPAL Entry = 0x%llx (entryp=%p basesz=%d)\n",
                 opal.entry, entryp, entrysz);
        pr_debug("OPAL Entry = 0x%llx (sizep=%p runtimesz=%d)\n",
                 opal.size, sizep, runtimesz);

        if (of_flat_dt_is_compatible(node, "ibm,opal-v3")) {
                powerpc_firmware_features |= FW_FEATURE_OPAL;
                pr_info("OPAL detected !\n");
        } else {
                panic("OPAL != V3 detected, no longer supported.\n");
        }

        return 1;
}

int __init early_init_dt_scan_recoverable_ranges(unsigned long node,
                                   const char *uname, int depth, void *data)
{
        int i, psize, size;
        const __be32 *prop;

        if (depth != 1 || strcmp(uname, "ibm,opal") != 0)
                return 0;

        prop = of_get_flat_dt_prop(node, "mcheck-recoverable-ranges", &psize);

        if (!prop)
                return 1;

        pr_debug("Found machine check recoverable ranges.\n");

        /*
         * Calculate number of available entries.
         *
         * Each recoverable address range entry is (start address, len,
         * recovery address), 2 cells each for start and recovery address,
         * 1 cell for len, totalling 5 cells per entry.
         */
        mc_recoverable_range_len = psize / (sizeof(*prop) * 5);

        /* Sanity check */
        if (!mc_recoverable_range_len)
                return 1;

        /* Size required to hold all the entries. */
        size = mc_recoverable_range_len *
                        sizeof(struct mcheck_recoverable_range);

        /*
         * Allocate a buffer to hold the MC recoverable ranges. We would be
         * accessing them in real mode, hence it needs to be within
         * RMO region.
         */
        mc_recoverable_range =__va(memblock_alloc_base(size, __alignof__(u64),
                                                        ppc64_rma_size));
        memset(mc_recoverable_range, 0, size);

        for (i = 0; i < mc_recoverable_range_len; i++) {
                mc_recoverable_range[i].start_addr =
                                        of_read_number(prop + (i * 5) + 0, 2);
                mc_recoverable_range[i].end_addr =
                                        mc_recoverable_range[i].start_addr +
                                        of_read_number(prop + (i * 5) + 2, 1);
                mc_recoverable_range[i].recover_addr =
                                        of_read_number(prop + (i * 5) + 3, 2);

                pr_debug("Machine check recoverable range: %llx..%llx: %llx\n",
                                mc_recoverable_range[i].start_addr,
                                mc_recoverable_range[i].end_addr,
                                mc_recoverable_range[i].recover_addr);
        }
        return 1;
}

static int __init opal_register_exception_handlers(void)
{
#ifdef __BIG_ENDIAN__
        u64 glue;

        if (!(powerpc_firmware_features & FW_FEATURE_OPAL))
                return -ENODEV;

        /* Hookup some exception handlers except machine check. We use the
         * fwnmi area at 0x7000 to provide the glue space to OPAL
         */
        glue = 0x7000;

        /*
         * Check if we are running on newer firmware that exports
         * OPAL_HANDLE_HMI token. If yes, then don't ask OPAL to patch
         * the HMI interrupt and we catch it directly in Linux.
         *
         * For older firmware (i.e currently released POWER8 System Firmware
         * as of today <= SV810_087), we fallback to old behavior and let OPAL
         * patch the HMI vector and handle it inside OPAL firmware.
         *
         * For newer firmware (in development/yet to be released) we will
         * start catching/handling HMI directly in Linux.
         */
        if (!opal_check_token(OPAL_HANDLE_HMI)) {
                pr_info("Old firmware detected, OPAL handles HMIs.\n");
                opal_register_exception_handler(
                                OPAL_HYPERVISOR_MAINTENANCE_HANDLER,
                                0, glue);
                glue += 128;
        }

        opal_register_exception_handler(OPAL_SOFTPATCH_HANDLER, 0, glue);
#endif

        return 0;
}
machine_early_initcall(powernv, opal_register_exception_handlers);

/*
 * Opal message notifier based on message type. Allow subscribers to get
 * notified for specific messgae type.
 */
int opal_message_notifier_register(enum opal_msg_type msg_type,
                                        struct notifier_block *nb)
{
        if (!nb || msg_type >= OPAL_MSG_TYPE_MAX) {
                pr_warning("%s: Invalid arguments, msg_type:%d\n",
                           __func__, msg_type);
                return -EINVAL;
        }

        return atomic_notifier_chain_register(
                                &opal_msg_notifier_head[msg_type], nb);
}
EXPORT_SYMBOL_GPL(opal_message_notifier_register);

int opal_message_notifier_unregister(enum opal_msg_type msg_type,
                                     struct notifier_block *nb)
{
        return atomic_notifier_chain_unregister(
                        &opal_msg_notifier_head[msg_type], nb);
}
EXPORT_SYMBOL_GPL(opal_message_notifier_unregister);

static void opal_message_do_notify(uint32_t msg_type, void *msg)
{
        /* notify subscribers */
        atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type],
                                        msg_type, msg);
}

static void opal_handle_message(void)
{
        s64 ret;
        /*
         * TODO: pre-allocate a message buffer depending on opal-msg-size
         * value in /proc/device-tree.
         */
        static struct opal_msg msg;
        u32 type;

        ret = opal_get_msg(__pa(&msg), sizeof(msg));
        /* No opal message pending. */
        if (ret == OPAL_RESOURCE)
                return;

        /* check for errors. */
        if (ret) {
                pr_warning("%s: Failed to retrieve opal message, err=%lld\n",
                                __func__, ret);
                return;
        }

        type = be32_to_cpu(msg.msg_type);

        /* Sanity check */
        if (type >= OPAL_MSG_TYPE_MAX) {
                pr_warn_once("%s: Unknown message type: %u\n", __func__, type);
                return;
        }
        opal_message_do_notify(type, (void *)&msg);
}

static irqreturn_t opal_message_notify(int irq, void *data)
{
        opal_handle_message();
        return IRQ_HANDLED;
}

static int __init opal_message_init(void)
{
        int ret, i, irq;

        for (i = 0; i < OPAL_MSG_TYPE_MAX; i++)
                ATOMIC_INIT_NOTIFIER_HEAD(&opal_msg_notifier_head[i]);

        irq = opal_event_request(ilog2(OPAL_EVENT_MSG_PENDING));
        if (!irq) {
                pr_err("%s: Can't register OPAL event irq (%d)\n",
                       __func__, irq);
                return irq;
        }

        ret = request_irq(irq, opal_message_notify,
                        IRQ_TYPE_LEVEL_HIGH, "opal-msg", NULL);
        if (ret) {
                pr_err("%s: Can't request OPAL event irq (%d)\n",
                       __func__, ret);
                return ret;
        }

        return 0;
}

int opal_get_chars(uint32_t vtermno, char *buf, int count)
{
        s64 rc;
        __be64 evt, len;

        if (!opal.entry)
                return -ENODEV;
        opal_poll_events(&evt);
        if ((be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_INPUT) == 0)
                return 0;
        len = cpu_to_be64(count);
        rc = opal_console_read(vtermno, &len, buf);
        if (rc == OPAL_SUCCESS)
                return be64_to_cpu(len);
        return 0;
}

int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
{
        int written = 0;
        __be64 olen;
        s64 len, rc;
        unsigned long flags;
        __be64 evt;

        if (!opal.entry)
                return -ENODEV;

        /* We want put_chars to be atomic to avoid mangling of hvsi
         * packets. To do that, we first test for room and return
         * -EAGAIN if there isn't enough.
         *
         * Unfortunately, opal_console_write_buffer_space() doesn't
         * appear to work on opal v1, so we just assume there is
         * enough room and be done with it
         */
        spin_lock_irqsave(&opal_write_lock, flags);
        rc = opal_console_write_buffer_space(vtermno, &olen);
        len = be64_to_cpu(olen);
        if (rc || len < total_len) {
                spin_unlock_irqrestore(&opal_write_lock, flags);
                /* Closed -> drop characters */
                if (rc)
                        return total_len;
                opal_poll_events(NULL);
                return -EAGAIN;
        }

        /* We still try to handle partial completions, though they
         * should no longer happen.
         */
        rc = OPAL_BUSY;
        while(total_len > 0 && (rc == OPAL_BUSY ||
                                rc == OPAL_BUSY_EVENT || rc == OPAL_SUCCESS)) {
                olen = cpu_to_be64(total_len);
                rc = opal_console_write(vtermno, &olen, data);
                len = be64_to_cpu(olen);

                /* Closed or other error drop */
                if (rc != OPAL_SUCCESS && rc != OPAL_BUSY &&
                    rc != OPAL_BUSY_EVENT) {
                        written = total_len;
                        break;
                }
                if (rc == OPAL_SUCCESS) {
                        total_len -= len;
                        data += len;
                        written += len;
                }
                /* This is a bit nasty but we need that for the console to
                 * flush when there aren't any interrupts. We will clean
                 * things a bit later to limit that to synchronous path
                 * such as the kernel console and xmon/udbg
                 */
                do
                        opal_poll_events(&evt);
                while(rc == OPAL_SUCCESS &&
                        (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT));
        }
        spin_unlock_irqrestore(&opal_write_lock, flags);
        return written;
}

static int opal_recover_mce(struct pt_regs *regs,
                                        struct machine_check_event *evt)
{
        int recovered = 0;

        if (!(regs->msr & MSR_RI)) {
                /* If MSR_RI isn't set, we cannot recover */
                pr_err("Machine check interrupt unrecoverable: MSR(RI=0)\n");
                recovered = 0;
        } else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {
                /* Platform corrected itself */
                recovered = 1;
        } else if (evt->severity == MCE_SEV_FATAL) {
                /* Fatal machine check */
                pr_err("Machine check interrupt is fatal\n");
                recovered = 0;
        } else if ((evt->severity == MCE_SEV_ERROR_SYNC) &&
                        (user_mode(regs) && !is_global_init(current))) {
                /*
                 * For now, kill the task if we have received exception when
                 * in userspace.
                 *
                 * TODO: Queue up this address for hwpoisioning later.
                 */
                _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
                recovered = 1;
        }
        return recovered;
}

int opal_machine_check(struct pt_regs *regs)
{
        struct machine_check_event evt;
        int ret;

        if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
                return 0;

        /* Print things out */
        if (evt.version != MCE_V1) {
                pr_err("Machine Check Exception, Unknown event version %d !\n",
                       evt.version);
                return 0;
        }
        machine_check_print_event_info(&evt);

        if (opal_recover_mce(regs, &evt))
                return 1;

        /*
         * Unrecovered machine check, we are heading to panic path.
         *
         * We may have hit this MCE in very early stage of kernel
         * initialization even before opal-prd has started running. If
         * this is the case then this MCE error may go un-noticed or
         * un-analyzed if we go down panic path. We need to inform
         * BMC/OCC about this error so that they can collect relevant
         * data for error analysis before rebooting.
         * Use opal_cec_reboot2(OPAL_REBOOT_PLATFORM_ERROR) to do so.
         * This function may not return on BMC based system.
         */
        ret = opal_cec_reboot2(OPAL_REBOOT_PLATFORM_ERROR,
                        "Unrecoverable Machine Check exception");
        if (ret == OPAL_UNSUPPORTED) {
                pr_emerg("Reboot type %d not supported\n",
                                        OPAL_REBOOT_PLATFORM_ERROR);
        }

        /*
         * We reached here. There can be three possibilities:
         * 1. We are running on a firmware level that do not support
         *    opal_cec_reboot2()
         * 2. We are running on a firmware level that do not support
         *    OPAL_REBOOT_PLATFORM_ERROR reboot type.
         * 3. We are running on FSP based system that does not need opal
         *    to trigger checkstop explicitly for error analysis. The FSP
         *    PRD component would have already got notified about this
         *    error through other channels.
         *
         * If hardware marked this as an unrecoverable MCE, we are
         * going to panic anyway. Even if it didn't, it's not safe to
         * continue at this point, so we should explicitly panic.
         */

        panic("PowerNV Unrecovered Machine Check");
        return 0;
}

/* Early hmi handler called in real mode. */
int opal_hmi_exception_early(struct pt_regs *regs)
{
        s64 rc;

        /*
         * call opal hmi handler. Pass paca address as token.
         * The return value OPAL_SUCCESS is an indication that there is
         * an HMI event generated waiting to pull by Linux.
         */
        rc = opal_handle_hmi();
        if (rc == OPAL_SUCCESS) {
                local_paca->hmi_event_available = 1;
                return 1;
        }
        return 0;
}

/* HMI exception handler called in virtual mode during check_irq_replay. */
int opal_handle_hmi_exception(struct pt_regs *regs)
{
        s64 rc;
        __be64 evt = 0;

        /*
         * Check if HMI event is available.
         * if Yes, then call opal_poll_events to pull opal messages and
         * process them.
         */
        if (!local_paca->hmi_event_available)
                return 0;

        local_paca->hmi_event_available = 0;
        rc = opal_poll_events(&evt);
        if (rc == OPAL_SUCCESS && evt)
                opal_handle_events(be64_to_cpu(evt));

        return 1;
}

static uint64_t find_recovery_address(uint64_t nip)
{
        int i;

        for (i = 0; i < mc_recoverable_range_len; i++)
                if ((nip >= mc_recoverable_range[i].start_addr) &&
                    (nip < mc_recoverable_range[i].end_addr))
                    return mc_recoverable_range[i].recover_addr;
        return 0;
}

bool opal_mce_check_early_recovery(struct pt_regs *regs)
{
        uint64_t recover_addr = 0;

        if (!opal.base || !opal.size)
                goto out;

        if ((regs->nip >= opal.base) &&
                        (regs->nip < (opal.base + opal.size)))
                recover_addr = find_recovery_address(regs->nip);

        /*
         * Setup regs->nip to rfi into fixup address.
         */
        if (recover_addr)
                regs->nip = recover_addr;

out:
        return !!recover_addr;
}

static int opal_sysfs_init(void)
{
        opal_kobj = kobject_create_and_add("opal", firmware_kobj);
        if (!opal_kobj) {
                pr_warn("kobject_create_and_add opal failed\n");
                return -ENOMEM;
        }

        return 0;
}

static ssize_t symbol_map_read(struct file *fp, struct kobject *kobj,
                               struct bin_attribute *bin_attr,
                               char *buf, loff_t off, size_t count)
{
        return memory_read_from_buffer(buf, count, &off, bin_attr->private,
                                       bin_attr->size);
}

static BIN_ATTR_RO(symbol_map, 0);

static void opal_export_symmap(void)
{
        const __be64 *syms;
        unsigned int size;
        struct device_node *fw;
        int rc;

        fw = of_find_node_by_path("/ibm,opal/firmware");
        if (!fw)
                return;
        syms = of_get_property(fw, "symbol-map", &size);
        if (!syms || size != 2 * sizeof(__be64))
                return;

        /* Setup attributes */
        bin_attr_symbol_map.private = __va(be64_to_cpu(syms[0]));
        bin_attr_symbol_map.size = be64_to_cpu(syms[1]);

        rc = sysfs_create_bin_file(opal_kobj, &bin_attr_symbol_map);
        if (rc)
                pr_warn("Error %d creating OPAL symbols file\n", rc);
}

static void __init opal_dump_region_init(void)
{
        void *addr;
        uint64_t size;
        int rc;

        if (!opal_check_token(OPAL_REGISTER_DUMP_REGION))
                return;

        /* Register kernel log buffer */
        addr = log_buf_addr_get();
        if (addr == NULL)
                return;

        size = log_buf_len_get();
        if (size == 0)
                return;

        rc = opal_register_dump_region(OPAL_DUMP_REGION_LOG_BUF,
                                       __pa(addr), size);
        /* Don't warn if this is just an older OPAL that doesn't
         * know about that call
         */
        if (rc && rc != OPAL_UNSUPPORTED)
                pr_warn("DUMP: Failed to register kernel log buffer. "
                        "rc = %d\n", rc);
}

static void opal_pdev_init(const char *compatible)
{
        struct device_node *np;

        for_each_compatible_node(np, NULL, compatible)
                of_platform_device_create(np, NULL, NULL);
}

static int kopald(void *unused)
{
        unsigned long timeout = msecs_to_jiffies(opal_heartbeat) + 1;
        __be64 events;

        set_freezable();
        do {
                try_to_freeze();
                opal_poll_events(&events);
                opal_handle_events(be64_to_cpu(events));
                schedule_timeout_interruptible(timeout);
        } while (!kthread_should_stop());

        return 0;
}

void opal_wake_poller(void)
{
        if (kopald_tsk)
                wake_up_process(kopald_tsk);
}

static void opal_init_heartbeat(void)
{
        /* Old firwmware, we assume the HVC heartbeat is sufficient */
        if (of_property_read_u32(opal_node, "ibm,heartbeat-ms",
                                 &opal_heartbeat) != 0)
                opal_heartbeat = 0;

        if (opal_heartbeat)
                kopald_tsk = kthread_run(kopald, NULL, "kopald");
}

static int __init opal_init(void)
{
        struct device_node *np, *consoles, *leds;
        int rc;

        opal_node = of_find_node_by_path("/ibm,opal");
        if (!opal_node) {
                pr_warn("Device node not found\n");
                return -ENODEV;
        }

        /* Register OPAL consoles if any ports */
        consoles = of_find_node_by_path("/ibm,opal/consoles");
        if (consoles) {
                for_each_child_of_node(consoles, np) {
                        if (strcmp(np->name, "serial"))
                                continue;
                        of_platform_device_create(np, NULL, NULL);
                }
                of_node_put(consoles);
        }

        /* Initialise OPAL messaging system */
        opal_message_init();

        /* Initialise OPAL asynchronous completion interface */
        opal_async_comp_init();

        /* Initialise OPAL sensor interface */
        opal_sensor_init();

        /* Initialise OPAL hypervisor maintainence interrupt handling */
        opal_hmi_handler_init();

        /* Create i2c platform devices */
        opal_pdev_init("ibm,opal-i2c");

        /* Setup a heatbeat thread if requested by OPAL */
        opal_init_heartbeat();

        /* Create leds platform devices */
        leds = of_find_node_by_path("/ibm,opal/leds");
        if (leds) {
                of_platform_device_create(leds, "opal_leds", NULL);
                of_node_put(leds);
        }

        /* Initialise OPAL message log interface */
        opal_msglog_init();

        /* Create "opal" kobject under /sys/firmware */
        rc = opal_sysfs_init();
        if (rc == 0) {
                /* Export symbol map to userspace */
                opal_export_symmap();
                /* Setup dump region interface */
                opal_dump_region_init();
                /* Setup error log interface */
                rc = opal_elog_init();
                /* Setup code update interface */
                opal_flash_update_init();
                /* Setup platform dump extract interface */
                opal_platform_dump_init();
                /* Setup system parameters interface */
                opal_sys_param_init();
                /* Setup message log sysfs interface. */
                opal_msglog_sysfs_init();
        }

        /* Initialize platform devices: IPMI backend, PRD & flash interface */
        opal_pdev_init("ibm,opal-ipmi");
        opal_pdev_init("ibm,opal-flash");
        opal_pdev_init("ibm,opal-prd");

        /* Initialise platform device: oppanel interface */
        opal_pdev_init("ibm,opal-oppanel");

        /* Initialise OPAL kmsg dumper for flushing console on panic */
        opal_kmsg_init();

        return 0;
}
machine_subsys_initcall(powernv, opal_init);

void opal_shutdown(void)
{
        long rc = OPAL_BUSY;

        opal_event_shutdown();

        /*
         * Then sync with OPAL which ensure anything that can
         * potentially write to our memory has completed such
         * as an ongoing dump retrieval
         */
        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_sync_host_reboot();
                if (rc == OPAL_BUSY)
                        opal_poll_events(NULL);
                else
                        mdelay(10);
        }

        /* Unregister memory dump region */
        if (opal_check_token(OPAL_UNREGISTER_DUMP_REGION))
                opal_unregister_dump_region(OPAL_DUMP_REGION_LOG_BUF);
}

/* Export this so that test modules can use it */
EXPORT_SYMBOL_GPL(opal_invalid_call);
EXPORT_SYMBOL_GPL(opal_xscom_read);
EXPORT_SYMBOL_GPL(opal_xscom_write);
EXPORT_SYMBOL_GPL(opal_ipmi_send);
EXPORT_SYMBOL_GPL(opal_ipmi_recv);
EXPORT_SYMBOL_GPL(opal_flash_read);
EXPORT_SYMBOL_GPL(opal_flash_write);
EXPORT_SYMBOL_GPL(opal_flash_erase);
EXPORT_SYMBOL_GPL(opal_prd_msg);

/* Convert a region of vmalloc memory to an opal sg list */
struct opal_sg_list *opal_vmalloc_to_sg_list(void *vmalloc_addr,
                                             unsigned long vmalloc_size)
{
        struct opal_sg_list *sg, *first = NULL;
        unsigned long i = 0;

        sg = kzalloc(PAGE_SIZE, GFP_KERNEL);
        if (!sg)
                goto nomem;

        first = sg;

        while (vmalloc_size > 0) {
                uint64_t data = vmalloc_to_pfn(vmalloc_addr) << PAGE_SHIFT;
                uint64_t length = min(vmalloc_size, PAGE_SIZE);

                sg->entry[i].data = cpu_to_be64(data);
                sg->entry[i].length = cpu_to_be64(length);
                i++;

                if (i >= SG_ENTRIES_PER_NODE) {
                        struct opal_sg_list *next;

                        next = kzalloc(PAGE_SIZE, GFP_KERNEL);
                        if (!next)
                                goto nomem;

                        sg->length = cpu_to_be64(
                                        i * sizeof(struct opal_sg_entry) + 16);
                        i = 0;
                        sg->next = cpu_to_be64(__pa(next));
                        sg = next;
                }

                vmalloc_addr += length;
                vmalloc_size -= length;
        }

        sg->length = cpu_to_be64(i * sizeof(struct opal_sg_entry) + 16);

        return first;

nomem:
        pr_err("%s : Failed to allocate memory\n", __func__);
        opal_free_sg_list(first);
        return NULL;
}

void opal_free_sg_list(struct opal_sg_list *sg)
{
        while (sg) {
                uint64_t next = be64_to_cpu(sg->next);

                kfree(sg);

                if (next)
                        sg = __va(next);
                else
                        sg = NULL;
        }
}

int opal_error_code(int rc)
{
        switch (rc) {
        case OPAL_SUCCESS:              return 0;

        case OPAL_PARAMETER:            return -EINVAL;
        case OPAL_ASYNC_COMPLETION:     return -EINPROGRESS;
        case OPAL_BUSY_EVENT:           return -EBUSY;
        case OPAL_NO_MEM:               return -ENOMEM;
        case OPAL_PERMISSION:           return -EPERM;

        case OPAL_UNSUPPORTED:          return -EIO;
        case OPAL_HARDWARE:             return -EIO;
        case OPAL_INTERNAL_ERROR:       return -EIO;
        default:
                pr_err("%s: unexpected OPAL error %d\n", __func__, rc);
                return -EIO;
        }
}

void powernv_set_nmmu_ptcr(unsigned long ptcr)
{
        int rc;

        if (firmware_has_feature(FW_FEATURE_OPAL)) {
                rc = opal_nmmu_set_ptcr(-1UL, ptcr);
                if (rc != OPAL_SUCCESS && rc != OPAL_UNSUPPORTED)
                        pr_warn("%s: Unable to set nest mmu ptcr\n", __func__);
        }
}

EXPORT_SYMBOL_GPL(opal_poll_events);
EXPORT_SYMBOL_GPL(opal_rtc_read);
EXPORT_SYMBOL_GPL(opal_rtc_write);
EXPORT_SYMBOL_GPL(opal_tpo_read);
EXPORT_SYMBOL_GPL(opal_tpo_write);
EXPORT_SYMBOL_GPL(opal_i2c_request);
/* Export these symbols for PowerNV LED class driver */
EXPORT_SYMBOL_GPL(opal_leds_get_ind);
EXPORT_SYMBOL_GPL(opal_leds_set_ind);
/* Export this symbol for PowerNV Operator Panel class driver */
EXPORT_SYMBOL_GPL(opal_write_oppanel_async);
/* Export this for KVM */
EXPORT_SYMBOL_GPL(opal_int_set_mfrr);