UBUNTU: Ubuntu-4.15.0-96.97

[mirror_ubuntu-bionic-kernel.git] / drivers / s390 / block / dasd_int.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * Copyright IBM Corp. 1999, 2009
 */

#ifndef DASD_INT_H
#define DASD_INT_H

/* we keep old device allocation scheme; IOW, minors are still in 0..255 */
#define DASD_PER_MAJOR (1U << (MINORBITS - DASD_PARTN_BITS))
#define DASD_PARTN_MASK ((1 << DASD_PARTN_BITS) - 1)

/*
 * States a dasd device can have:
 *   new: the dasd_device structure is allocated.
 *   known: the discipline for the device is identified.
 *   basic: the device can do basic i/o.
 *   unfmt: the device could not be analyzed (format is unknown).
 *   ready: partition detection is done and the device is can do block io.
 *   online: the device accepts requests from the block device queue.
 *
 * Things to do for startup state transitions:
 *   new -> known: find discipline for the device and create devfs entries.
 *   known -> basic: request irq line for the device.
 *   basic -> ready: do the initial analysis, e.g. format detection,
 *                   do block device setup and detect partitions.
 *   ready -> online: schedule the device tasklet.
 * Things to do for shutdown state transitions:
 *   online -> ready: just set the new device state.
 *   ready -> basic: flush requests from the block device layer, clear
 *                   partition information and reset format information.
 *   basic -> known: terminate all requests and free irq.
 *   known -> new: remove devfs entries and forget discipline.
 */

#define DASD_STATE_NEW    0
#define DASD_STATE_KNOWN  1
#define DASD_STATE_BASIC  2
#define DASD_STATE_UNFMT  3
#define DASD_STATE_READY  4
#define DASD_STATE_ONLINE 5

#include <linux/module.h>
#include <linux/wait.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/interrupt.h>
#include <linux/log2.h>
#include <asm/ccwdev.h>
#include <linux/workqueue.h>
#include <asm/debug.h>
#include <asm/dasd.h>
#include <asm/idals.h>
#include <linux/bitops.h>
#include <linux/blk-mq.h>

/* DASD discipline magic */
#define DASD_ECKD_MAGIC 0xC5C3D2C4
#define DASD_DIAG_MAGIC 0xC4C9C1C7
#define DASD_FBA_MAGIC 0xC6C2C140

/*
 * SECTION: Type definitions
 */
struct dasd_device;
struct dasd_block;

/* BIT DEFINITIONS FOR SENSE DATA */
#define DASD_SENSE_BIT_0 0x80
#define DASD_SENSE_BIT_1 0x40
#define DASD_SENSE_BIT_2 0x20
#define DASD_SENSE_BIT_3 0x10

/* BIT DEFINITIONS FOR SIM SENSE */
#define DASD_SIM_SENSE 0x0F
#define DASD_SIM_MSG_TO_OP 0x03
#define DASD_SIM_LOG 0x0C

/* lock class for nested cdev lock */
#define CDEV_NESTED_FIRST 1
#define CDEV_NESTED_SECOND 2

/*
 * SECTION: MACROs for klogd and s390 debug feature (dbf)
 */
#define DBF_DEV_EVENT(d_level, d_device, d_str, d_data...) \
do { \
        debug_sprintf_event(d_device->debug_area, \
                            d_level, \
                            d_str "\n", \
                            d_data); \
} while(0)

#define DBF_EVENT(d_level, d_str, d_data...)\
do { \
        debug_sprintf_event(dasd_debug_area, \
                            d_level,\
                            d_str "\n", \
                            d_data); \
} while(0)

#define DBF_EVENT_DEVID(d_level, d_cdev, d_str, d_data...)      \
do { \
        struct ccw_dev_id __dev_id;                     \
        ccw_device_get_id(d_cdev, &__dev_id);           \
        debug_sprintf_event(dasd_debug_area,            \
                            d_level,                                    \
                            "0.%x.%04x " d_str "\n",                    \
                            __dev_id.ssid, __dev_id.devno, d_data);     \
} while (0)

/* limit size for an errorstring */
#define ERRORLENGTH 30

/* definition of dbf debug levels */
#define DBF_EMERG       0       /* system is unusable                   */
#define DBF_ALERT       1       /* action must be taken immediately     */
#define DBF_CRIT        2       /* critical conditions                  */
#define DBF_ERR         3       /* error conditions                     */
#define DBF_WARNING     4       /* warning conditions                   */
#define DBF_NOTICE      5       /* normal but significant condition     */
#define DBF_INFO        6       /* informational                        */
#define DBF_DEBUG       6       /* debug-level messages                 */

/* messages to be written via klogd and dbf */
#define DEV_MESSAGE(d_loglevel,d_device,d_string,d_args...)\
do { \
        printk(d_loglevel PRINTK_HEADER " %s: " d_string "\n", \
               dev_name(&d_device->cdev->dev), d_args); \
        DBF_DEV_EVENT(DBF_ALERT, d_device, d_string, d_args); \
} while(0)

#define MESSAGE(d_loglevel,d_string,d_args...)\
do { \
        printk(d_loglevel PRINTK_HEADER " " d_string "\n", d_args); \
        DBF_EVENT(DBF_ALERT, d_string, d_args); \
} while(0)

/* messages to be written via klogd only */
#define DEV_MESSAGE_LOG(d_loglevel,d_device,d_string,d_args...)\
do { \
        printk(d_loglevel PRINTK_HEADER " %s: " d_string "\n", \
               dev_name(&d_device->cdev->dev), d_args); \
} while(0)

#define MESSAGE_LOG(d_loglevel,d_string,d_args...)\
do { \
        printk(d_loglevel PRINTK_HEADER " " d_string "\n", d_args); \
} while(0)

/* Macro to calculate number of blocks per page */
#define BLOCKS_PER_PAGE(blksize) (PAGE_SIZE / blksize)

struct dasd_ccw_req {
        unsigned int magic;             /* Eye catcher */
        struct list_head devlist;       /* for dasd_device request queue */
        struct list_head blocklist;     /* for dasd_block request queue */

        /* Where to execute what... */
        struct dasd_block *block;       /* the originating block device */
        struct dasd_device *memdev;     /* the device used to allocate this */
        struct dasd_device *startdev;   /* device the request is started on */
        struct dasd_device *basedev;    /* base device if no block->base */
        void *cpaddr;                   /* address of ccw or tcw */
        unsigned char cpmode;           /* 0 = cmd mode, 1 = itcw */
        char status;                    /* status of this request */
        short retries;                  /* A retry counter */
        unsigned long flags;            /* flags of this request */
        struct dasd_queue *dq;

        /* ... and how */
        unsigned long starttime;        /* jiffies time of request start */
        unsigned long expires;          /* expiration period in jiffies */
        char lpm;                       /* logical path mask */
        void *data;                     /* pointer to data area */

        /* these are important for recovering erroneous requests          */
        int intrc;                      /* internal error, e.g. from start_IO */
        struct irb irb;                 /* device status in case of an error */
        struct dasd_ccw_req *refers;    /* ERP-chain queueing. */
        void *function;                 /* originating ERP action */

        /* these are for statistics only */
        unsigned long buildclk;         /* TOD-clock of request generation */
        unsigned long startclk;         /* TOD-clock of request start */
        unsigned long stopclk;          /* TOD-clock of request interrupt */
        unsigned long endclk;           /* TOD-clock of request termination */

        /* Callback that is called after reaching final status. */
        void (*callback)(struct dasd_ccw_req *, void *data);
        void *callback_data;
};

/*
 * dasd_ccw_req -> status can be:
 */
#define DASD_CQR_FILLED         0x00    /* request is ready to be processed */
#define DASD_CQR_DONE           0x01    /* request is completed successfully */
#define DASD_CQR_NEED_ERP       0x02    /* request needs recovery action */
#define DASD_CQR_IN_ERP         0x03    /* request is in recovery */
#define DASD_CQR_FAILED         0x04    /* request is finally failed */
#define DASD_CQR_TERMINATED     0x05    /* request was stopped by driver */

#define DASD_CQR_QUEUED         0x80    /* request is queued to be processed */
#define DASD_CQR_IN_IO          0x81    /* request is currently in IO */
#define DASD_CQR_ERROR          0x82    /* request is completed with error */
#define DASD_CQR_CLEAR_PENDING  0x83    /* request is clear pending */
#define DASD_CQR_CLEARED        0x84    /* request was cleared */
#define DASD_CQR_SUCCESS        0x85    /* request was successful */

/* default expiration time*/
#define DASD_EXPIRES      300
#define DASD_EXPIRES_MAX  40000000
#define DASD_RETRIES      256
#define DASD_RETRIES_MAX  32768

/* per dasd_ccw_req flags */
#define DASD_CQR_FLAGS_USE_ERP   0      /* use ERP for this request */
#define DASD_CQR_FLAGS_FAILFAST  1      /* FAILFAST */
#define DASD_CQR_VERIFY_PATH     2      /* path verification request */
#define DASD_CQR_ALLOW_SLOCK     3      /* Try this request even when lock was
                                         * stolen. Should not be combined with
                                         * DASD_CQR_FLAGS_USE_ERP
                                         */
/*
 * The following flags are used to suppress output of certain errors.
 */
#define DASD_CQR_SUPPRESS_NRF   4       /* Suppress 'No Record Found' error */
#define DASD_CQR_SUPPRESS_FP    5       /* Suppress 'File Protected' error*/
#define DASD_CQR_SUPPRESS_IL    6       /* Suppress 'Incorrect Length' error */
#define DASD_CQR_SUPPRESS_CR    7       /* Suppress 'Command Reject' error */

#define DASD_REQ_PER_DEV 4

/* Signature for error recovery functions. */
typedef struct dasd_ccw_req *(*dasd_erp_fn_t) (struct dasd_ccw_req *);

/*
 * A single CQR can only contain a maximum of 255 CCWs. It is limited by
 * the locate record and locate record extended count value which can only hold
 * 1 Byte max.
 */
#define DASD_CQR_MAX_CCW 255

/*
 * Unique identifier for dasd device.
 */
#define UA_NOT_CONFIGURED  0x00
#define UA_BASE_DEVICE     0x01
#define UA_BASE_PAV_ALIAS  0x02
#define UA_HYPER_PAV_ALIAS 0x03

struct dasd_uid {
        __u8 type;
        char vendor[4];
        char serial[15];
        __u16 ssid;
        __u8 real_unit_addr;
        __u8 base_unit_addr;
        char vduit[33];
};

/*
 * the struct dasd_discipline is
 * sth like a table of virtual functions, if you think of dasd_eckd
 * inheriting dasd...
 * no, currently we are not planning to reimplement the driver in C++
 */
struct dasd_discipline {
        struct module *owner;
        char ebcname[8];        /* a name used for tagging and printks */
        char name[8];           /* a name used for tagging and printks */
        int max_blocks;         /* maximum number of blocks to be chained */

        struct list_head list;  /* used for list of disciplines */

        /*
         * Device recognition functions. check_device is used to verify
         * the sense data and the information returned by read device
         * characteristics. It returns 0 if the discipline can be used
         * for the device in question. uncheck_device is called during
         * device shutdown to deregister a device from its discipline.
         */
        int (*check_device) (struct dasd_device *);
        void (*uncheck_device) (struct dasd_device *);

        /*
         * do_analysis is used in the step from device state "basic" to
         * state "accept". It returns 0 if the device can be made ready,
         * it returns -EMEDIUMTYPE if the device can't be made ready or
         * -EAGAIN if do_analysis started a ccw that needs to complete
         * before the analysis may be repeated.
         */
        int (*do_analysis) (struct dasd_block *);

        /*
         * This function is called, when new paths become available.
         * Disciplins may use this callback to do necessary setup work,
         * e.g. verify that new path is compatible with the current
         * configuration.
         */
        int (*verify_path)(struct dasd_device *, __u8);

        /*
         * Last things to do when a device is set online, and first things
         * when it is set offline.
         */
        int (*basic_to_ready) (struct dasd_device *);
        int (*online_to_ready) (struct dasd_device *);
        int (*basic_to_known)(struct dasd_device *);

        /* (struct dasd_device *);
         * Device operation functions. build_cp creates a ccw chain for
         * a block device request, start_io starts the request and
         * term_IO cancels it (e.g. in case of a timeout). format_device
         * formats the device and check_device_format compares the format of
         * a device with the expected format_data.
         * handle_terminated_request allows to examine a cqr and prepare
         * it for retry.
         */
        struct dasd_ccw_req *(*build_cp) (struct dasd_device *,
                                          struct dasd_block *,
                                          struct request *);
        int (*start_IO) (struct dasd_ccw_req *);
        int (*term_IO) (struct dasd_ccw_req *);
        void (*handle_terminated_request) (struct dasd_ccw_req *);
        int (*format_device) (struct dasd_device *,
                              struct format_data_t *, int);
        int (*check_device_format)(struct dasd_device *,
                                   struct format_check_t *, int);
        int (*free_cp) (struct dasd_ccw_req *, struct request *);

        /*
         * Error recovery functions. examine_error() returns a value that
         * indicates what to do for an error condition. If examine_error()
         * returns 'dasd_era_recover' erp_action() is called to create a
         * special error recovery ccw. erp_postaction() is called after
         * an error recovery ccw has finished its execution. dump_sense
         * is called for every error condition to print the sense data
         * to the console.
         */
        dasd_erp_fn_t(*erp_action) (struct dasd_ccw_req *);
        dasd_erp_fn_t(*erp_postaction) (struct dasd_ccw_req *);
        void (*dump_sense) (struct dasd_device *, struct dasd_ccw_req *,
                            struct irb *);
        void (*dump_sense_dbf) (struct dasd_device *, struct irb *, char *);
        void (*check_for_device_change) (struct dasd_device *,
                                         struct dasd_ccw_req *,
                                         struct irb *);

        /* i/o control functions. */
        int (*fill_geometry) (struct dasd_block *, struct hd_geometry *);
        int (*fill_info) (struct dasd_device *, struct dasd_information2_t *);
        int (*ioctl) (struct dasd_block *, unsigned int, void __user *);

        /* suspend/resume functions */
        int (*freeze) (struct dasd_device *);
        int (*restore) (struct dasd_device *);

        /* reload device after state change */
        int (*reload) (struct dasd_device *);

        int (*get_uid) (struct dasd_device *, struct dasd_uid *);
        void (*kick_validate) (struct dasd_device *);
        int (*check_attention)(struct dasd_device *, __u8);
        int (*host_access_count)(struct dasd_device *);
        int (*hosts_print)(struct dasd_device *, struct seq_file *);
        void (*handle_hpf_error)(struct dasd_device *, struct irb *);
        void (*disable_hpf)(struct dasd_device *);
        int (*hpf_enabled)(struct dasd_device *);
        void (*reset_path)(struct dasd_device *, __u8);
};

extern struct dasd_discipline *dasd_diag_discipline_pointer;

/*
 * Notification numbers for extended error reporting notifications:
 * The DASD_EER_DISABLE notification is sent before a dasd_device (and it's
 * eer pointer) is freed. The error reporting module needs to do all necessary
 * cleanup steps.
 * The DASD_EER_TRIGGER notification sends the actual error reports (triggers).
 */
#define DASD_EER_DISABLE 0
#define DASD_EER_TRIGGER 1

/* Trigger IDs for extended error reporting DASD_EER_TRIGGER notification */
#define DASD_EER_FATALERROR  1
#define DASD_EER_NOPATH      2
#define DASD_EER_STATECHANGE 3
#define DASD_EER_PPRCSUSPEND 4

/* DASD path handling */

#define DASD_PATH_OPERATIONAL  1
#define DASD_PATH_TBV          2
#define DASD_PATH_PP           3
#define DASD_PATH_NPP          4
#define DASD_PATH_MISCABLED    5
#define DASD_PATH_NOHPF        6
#define DASD_PATH_CUIR         7
#define DASD_PATH_IFCC         8

#define DASD_THRHLD_MAX         4294967295U
#define DASD_INTERVAL_MAX       4294967295U

struct dasd_path {
        unsigned long flags;
        u8 cssid;
        u8 ssid;
        u8 chpid;
        struct dasd_conf_data *conf_data;
        atomic_t error_count;
        unsigned long errorclk;
};


struct dasd_profile_info {
        /* legacy part of profile data, as in dasd_profile_info_t */
        unsigned int dasd_io_reqs;       /* number of requests processed */
        unsigned int dasd_io_sects;      /* number of sectors processed */
        unsigned int dasd_io_secs[32];   /* histogram of request's sizes */
        unsigned int dasd_io_times[32];  /* histogram of requests's times */
        unsigned int dasd_io_timps[32];  /* h. of requests's times per sector */
        unsigned int dasd_io_time1[32];  /* hist. of time from build to start */
        unsigned int dasd_io_time2[32];  /* hist. of time from start to irq */
        unsigned int dasd_io_time2ps[32]; /* hist. of time from start to irq */
        unsigned int dasd_io_time3[32];  /* hist. of time from irq to end */
        unsigned int dasd_io_nr_req[32]; /* hist. of # of requests in chanq */

        /* new data */
        struct timespec64 starttod;        /* time of start or last reset */
        unsigned int dasd_io_alias;        /* requests using an alias */
        unsigned int dasd_io_tpm;          /* requests using transport mode */
        unsigned int dasd_read_reqs;       /* total number of read  requests */
        unsigned int dasd_read_sects;      /* total number read sectors */
        unsigned int dasd_read_alias;      /* read request using an alias */
        unsigned int dasd_read_tpm;        /* read requests in transport mode */
        unsigned int dasd_read_secs[32];   /* histogram of request's sizes */
        unsigned int dasd_read_times[32];  /* histogram of requests's times */
        unsigned int dasd_read_time1[32];  /* hist. time from build to start */
        unsigned int dasd_read_time2[32];  /* hist. of time from start to irq */
        unsigned int dasd_read_time3[32];  /* hist. of time from irq to end */
        unsigned int dasd_read_nr_req[32]; /* hist. of # of requests in chanq */
        unsigned long dasd_sum_times;      /* sum of request times */
        unsigned long dasd_sum_time_str;   /* sum of time from build to start */
        unsigned long dasd_sum_time_irq;   /* sum of time from start to irq */
        unsigned long dasd_sum_time_end;   /* sum of time from irq to end */
};

struct dasd_profile {
        struct dentry *dentry;
        struct dasd_profile_info *data;
        spinlock_t lock;
};

struct dasd_device {
        /* Block device stuff. */
        struct dasd_block *block;

        unsigned int devindex;
        unsigned long flags;       /* per device flags */
        unsigned short features;   /* copy of devmap-features (read-only!) */

        /* extended error reporting stuff (eer) */
        struct dasd_ccw_req *eer_cqr;

        /* Device discipline stuff. */
        struct dasd_discipline *discipline;
        struct dasd_discipline *base_discipline;
        void *private;
        struct dasd_path path[8];
        __u8 opm;

        /* Device state and target state. */
        int state, target;
        struct mutex state_mutex;
        int stopped;            /* device (ccw_device_start) was stopped */

        /* reference count. */
        atomic_t ref_count;

        /* ccw queue and memory for static ccw/erp buffers. */
        struct list_head ccw_queue;
        spinlock_t mem_lock;
        void *ccw_mem;
        void *erp_mem;
        struct list_head ccw_chunks;
        struct list_head erp_chunks;

        atomic_t tasklet_scheduled;
        struct tasklet_struct tasklet;
        struct work_struct kick_work;
        struct work_struct restore_device;
        struct work_struct reload_device;
        struct work_struct kick_validate;
        struct work_struct suc_work;
        struct work_struct requeue_requests;
        struct timer_list timer;

        debug_info_t *debug_area;

        struct ccw_device *cdev;

        /* hook for alias management */
        struct list_head alias_list;

        /* default expiration time in s */
        unsigned long default_expires;
        unsigned long default_retries;

        unsigned long blk_timeout;

        unsigned long path_thrhld;
        unsigned long path_interval;

        struct dentry *debugfs_dentry;
        struct dentry *hosts_dentry;
        struct dasd_profile profile;
};

struct dasd_block {
        /* Block device stuff. */
        struct gendisk *gdp;
        struct request_queue *request_queue;
        spinlock_t request_queue_lock;
        struct blk_mq_tag_set tag_set;
        struct block_device *bdev;
        atomic_t open_count;

        unsigned long blocks;      /* size of volume in blocks */
        unsigned int bp_block;     /* bytes per block */
        unsigned int s2b_shift;    /* log2 (bp_block/512) */

        struct dasd_device *base;
        struct list_head ccw_queue;
        spinlock_t queue_lock;

        atomic_t tasklet_scheduled;
        struct tasklet_struct tasklet;
        struct timer_list timer;

        struct dentry *debugfs_dentry;
        struct dasd_profile profile;
};

struct dasd_attention_data {
        struct dasd_device *device;
        __u8 lpum;
};

struct dasd_queue {
        spinlock_t lock;
};

/* reasons why device (ccw_device_start) was stopped */
#define DASD_STOPPED_NOT_ACC 1         /* not accessible */
#define DASD_STOPPED_QUIESCE 2         /* Quiesced */
#define DASD_STOPPED_PENDING 4         /* long busy */
#define DASD_STOPPED_DC_WAIT 8         /* disconnected, wait */
#define DASD_STOPPED_SU      16        /* summary unit check handling */
#define DASD_STOPPED_PM      32        /* pm state transition */
#define DASD_UNRESUMED_PM    64        /* pm resume failed state */

/* per device flags */
#define DASD_FLAG_OFFLINE       3       /* device is in offline processing */
#define DASD_FLAG_EER_SNSS      4       /* A SNSS is required */
#define DASD_FLAG_EER_IN_USE    5       /* A SNSS request is running */
#define DASD_FLAG_DEVICE_RO     6       /* The device itself is read-only. Don't
                                         * confuse this with the user specified
                                         * read-only feature.
                                         */
#define DASD_FLAG_IS_RESERVED   7       /* The device is reserved */
#define DASD_FLAG_LOCK_STOLEN   8       /* The device lock was stolen */
#define DASD_FLAG_SUSPENDED     9       /* The device was suspended */
#define DASD_FLAG_SAFE_OFFLINE  10      /* safe offline processing requested*/
#define DASD_FLAG_SAFE_OFFLINE_RUNNING  11      /* safe offline running */
#define DASD_FLAG_ABORTALL      12      /* Abort all noretry requests */
#define DASD_FLAG_PATH_VERIFY   13      /* Path verification worker running */
#define DASD_FLAG_SUC           14      /* unhandled summary unit check */

#define DASD_SLEEPON_START_TAG  ((void *) 1)
#define DASD_SLEEPON_END_TAG    ((void *) 2)

void dasd_put_device_wake(struct dasd_device *);

/*
 * Reference count inliners
 */
static inline void
dasd_get_device(struct dasd_device *device)
{
        atomic_inc(&device->ref_count);
}

static inline void
dasd_put_device(struct dasd_device *device)
{
        if (atomic_dec_return(&device->ref_count) == 0)
                dasd_put_device_wake(device);
}

/*
 * The static memory in ccw_mem and erp_mem is managed by a sorted
 * list of free memory chunks.
 */
struct dasd_mchunk
{
        struct list_head list;
        unsigned long size;
} __attribute__ ((aligned(8)));

static inline void
dasd_init_chunklist(struct list_head *chunk_list, void *mem,
                    unsigned long size)
{
        struct dasd_mchunk *chunk;

        INIT_LIST_HEAD(chunk_list);
        chunk = (struct dasd_mchunk *) mem;
        chunk->size = size - sizeof(struct dasd_mchunk);
        list_add(&chunk->list, chunk_list);
}

static inline void *
dasd_alloc_chunk(struct list_head *chunk_list, unsigned long size)
{
        struct dasd_mchunk *chunk, *tmp;

        size = (size + 7L) & -8L;
        list_for_each_entry(chunk, chunk_list, list) {
                if (chunk->size < size)
                        continue;
                if (chunk->size > size + sizeof(struct dasd_mchunk)) {
                        char *endaddr = (char *) (chunk + 1) + chunk->size;
                        tmp = (struct dasd_mchunk *) (endaddr - size) - 1;
                        tmp->size = size;
                        chunk->size -= size + sizeof(struct dasd_mchunk);
                        chunk = tmp;
                } else
                        list_del(&chunk->list);
                return (void *) (chunk + 1);
        }
        return NULL;
}

static inline void
dasd_free_chunk(struct list_head *chunk_list, void *mem)
{
        struct dasd_mchunk *chunk, *tmp;
        struct list_head *p, *left;

        chunk = (struct dasd_mchunk *)
                ((char *) mem - sizeof(struct dasd_mchunk));
        /* Find out the left neighbour in chunk_list. */
        left = chunk_list;
        list_for_each(p, chunk_list) {
                if (list_entry(p, struct dasd_mchunk, list) > chunk)
                        break;
                left = p;
        }
        /* Try to merge with right neighbour = next element from left. */
        if (left->next != chunk_list) {
                tmp = list_entry(left->next, struct dasd_mchunk, list);
                if ((char *) (chunk + 1) + chunk->size == (char *) tmp) {
                        list_del(&tmp->list);
                        chunk->size += tmp->size + sizeof(struct dasd_mchunk);
                }
        }
        /* Try to merge with left neighbour. */
        if (left != chunk_list) {
                tmp = list_entry(left, struct dasd_mchunk, list);
                if ((char *) (tmp + 1) + tmp->size == (char *) chunk) {
                        tmp->size += chunk->size + sizeof(struct dasd_mchunk);
                        return;
                }
        }
        __list_add(&chunk->list, left, left->next);
}

/*
 * Check if bsize is in { 512, 1024, 2048, 4096 }
 */
static inline int
dasd_check_blocksize(int bsize)
{
        if (bsize < 512 || bsize > 4096 || !is_power_of_2(bsize))
                return -EMEDIUMTYPE;
        return 0;
}

/* externals in dasd.c */
#define DASD_PROFILE_OFF         0
#define DASD_PROFILE_ON          1
#define DASD_PROFILE_GLOBAL_ONLY 2

extern debug_info_t *dasd_debug_area;
extern struct dasd_profile dasd_global_profile;
extern unsigned int dasd_global_profile_level;
extern const struct block_device_operations dasd_device_operations;

extern struct kmem_cache *dasd_page_cache;

struct dasd_ccw_req *
dasd_kmalloc_request(int , int, int, struct dasd_device *);
struct dasd_ccw_req *
dasd_smalloc_request(int , int, int, struct dasd_device *);
void dasd_kfree_request(struct dasd_ccw_req *, struct dasd_device *);
void dasd_sfree_request(struct dasd_ccw_req *, struct dasd_device *);
void dasd_wakeup_cb(struct dasd_ccw_req *, void *);

static inline int
dasd_kmalloc_set_cda(struct ccw1 *ccw, void *cda, struct dasd_device *device)
{
        return set_normalized_cda(ccw, cda);
}

struct dasd_device *dasd_alloc_device(void);
void dasd_free_device(struct dasd_device *);

struct dasd_block *dasd_alloc_block(void);
void dasd_free_block(struct dasd_block *);

enum blk_eh_timer_return dasd_times_out(struct request *req, bool reserved);

void dasd_enable_device(struct dasd_device *);
void dasd_set_target_state(struct dasd_device *, int);
void dasd_kick_device(struct dasd_device *);
void dasd_restore_device(struct dasd_device *);
void dasd_reload_device(struct dasd_device *);
void dasd_schedule_requeue(struct dasd_device *);

void dasd_add_request_head(struct dasd_ccw_req *);
void dasd_add_request_tail(struct dasd_ccw_req *);
int  dasd_start_IO(struct dasd_ccw_req *);
int  dasd_term_IO(struct dasd_ccw_req *);
void dasd_schedule_device_bh(struct dasd_device *);
void dasd_schedule_block_bh(struct dasd_block *);
int  dasd_sleep_on(struct dasd_ccw_req *);
int  dasd_sleep_on_queue(struct list_head *);
int  dasd_sleep_on_immediatly(struct dasd_ccw_req *);
int  dasd_sleep_on_interruptible(struct dasd_ccw_req *);
void dasd_device_set_timer(struct dasd_device *, int);
void dasd_device_clear_timer(struct dasd_device *);
void dasd_block_set_timer(struct dasd_block *, int);
void dasd_block_clear_timer(struct dasd_block *);
int  dasd_cancel_req(struct dasd_ccw_req *);
int dasd_flush_device_queue(struct dasd_device *);
int dasd_generic_probe (struct ccw_device *, struct dasd_discipline *);
void dasd_generic_free_discipline(struct dasd_device *);
void dasd_generic_remove (struct ccw_device *cdev);
int dasd_generic_set_online(struct ccw_device *, struct dasd_discipline *);
int dasd_generic_set_offline (struct ccw_device *cdev);
int dasd_generic_notify(struct ccw_device *, int);
int dasd_generic_last_path_gone(struct dasd_device *);
int dasd_generic_path_operational(struct dasd_device *);
void dasd_generic_shutdown(struct ccw_device *);

void dasd_generic_handle_state_change(struct dasd_device *);
int dasd_generic_pm_freeze(struct ccw_device *);
int dasd_generic_restore_device(struct ccw_device *);
enum uc_todo dasd_generic_uc_handler(struct ccw_device *, struct irb *);
void dasd_generic_path_event(struct ccw_device *, int *);
int dasd_generic_verify_path(struct dasd_device *, __u8);

int dasd_generic_read_dev_chars(struct dasd_device *, int, void *, int);
char *dasd_get_sense(struct irb *);

void dasd_device_set_stop_bits(struct dasd_device *, int);
void dasd_device_remove_stop_bits(struct dasd_device *, int);

int dasd_device_is_ro(struct dasd_device *);

void dasd_profile_reset(struct dasd_profile *);
int dasd_profile_on(struct dasd_profile *);
void dasd_profile_off(struct dasd_profile *);
char *dasd_get_user_string(const char __user *, size_t);

/* externals in dasd_devmap.c */
extern int dasd_max_devindex;
extern int dasd_probeonly;
extern int dasd_autodetect;
extern int dasd_nopav;
extern int dasd_nofcx;

int dasd_devmap_init(void);
void dasd_devmap_exit(void);

struct dasd_device *dasd_create_device(struct ccw_device *);
void dasd_delete_device(struct dasd_device *);

int dasd_get_feature(struct ccw_device *, int);
int dasd_set_feature(struct ccw_device *, int, int);

int dasd_add_sysfs_files(struct ccw_device *);
void dasd_remove_sysfs_files(struct ccw_device *);

struct dasd_device *dasd_device_from_cdev(struct ccw_device *);
struct dasd_device *dasd_device_from_cdev_locked(struct ccw_device *);
struct dasd_device *dasd_device_from_devindex(int);

void dasd_add_link_to_gendisk(struct gendisk *, struct dasd_device *);
struct dasd_device *dasd_device_from_gendisk(struct gendisk *);

int dasd_parse(void) __init;
int dasd_busid_known(const char *);

/* externals in dasd_gendisk.c */
int  dasd_gendisk_init(void);
void dasd_gendisk_exit(void);
int dasd_gendisk_alloc(struct dasd_block *);
void dasd_gendisk_free(struct dasd_block *);
int dasd_scan_partitions(struct dasd_block *);
void dasd_destroy_partitions(struct dasd_block *);

/* externals in dasd_ioctl.c */
int  dasd_ioctl(struct block_device *, fmode_t, unsigned int, unsigned long);

/* externals in dasd_proc.c */
int dasd_proc_init(void);
void dasd_proc_exit(void);

/* externals in dasd_erp.c */
struct dasd_ccw_req *dasd_default_erp_action(struct dasd_ccw_req *);
struct dasd_ccw_req *dasd_default_erp_postaction(struct dasd_ccw_req *);
struct dasd_ccw_req *dasd_alloc_erp_request(char *, int, int,
                                            struct dasd_device *);
void dasd_free_erp_request(struct dasd_ccw_req *, struct dasd_device *);
void dasd_log_sense(struct dasd_ccw_req *, struct irb *);
void dasd_log_sense_dbf(struct dasd_ccw_req *cqr, struct irb *irb);

/* externals in dasd_3990_erp.c */
struct dasd_ccw_req *dasd_3990_erp_action(struct dasd_ccw_req *);
void dasd_3990_erp_handle_sim(struct dasd_device *, char *);

/* externals in dasd_eer.c */
#ifdef CONFIG_DASD_EER
int dasd_eer_init(void);
void dasd_eer_exit(void);
int dasd_eer_enable(struct dasd_device *);
void dasd_eer_disable(struct dasd_device *);
void dasd_eer_write(struct dasd_device *, struct dasd_ccw_req *cqr,
                    unsigned int id);
void dasd_eer_snss(struct dasd_device *);

static inline int dasd_eer_enabled(struct dasd_device *device)
{
        return device->eer_cqr != NULL;
}
#else
#define dasd_eer_init()         (0)
#define dasd_eer_exit()         do { } while (0)
#define dasd_eer_enable(d)      (0)
#define dasd_eer_disable(d)     do { } while (0)
#define dasd_eer_write(d,c,i)   do { } while (0)
#define dasd_eer_snss(d)        do { } while (0)
#define dasd_eer_enabled(d)     (0)
#endif  /* CONFIG_DASD_ERR */


/* DASD path handling functions */

/*
 * helper functions to modify bit masks for a given channel path for a device
 */
static inline int dasd_path_is_operational(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_OPERATIONAL, &device->path[chp].flags);
}

static inline int dasd_path_need_verify(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_TBV, &device->path[chp].flags);
}

static inline void dasd_path_verify(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_TBV, &device->path[chp].flags);
}

static inline void dasd_path_clear_verify(struct dasd_device *device, int chp)
{
        __clear_bit(DASD_PATH_TBV, &device->path[chp].flags);
}

static inline void dasd_path_clear_all_verify(struct dasd_device *device)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                dasd_path_clear_verify(device, chp);
}

static inline void dasd_path_operational(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_OPERATIONAL, &device->path[chp].flags);
        device->opm |= (0x80 >> chp);
}

static inline void dasd_path_nonpreferred(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_NPP, &device->path[chp].flags);
}

static inline int dasd_path_is_nonpreferred(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_NPP, &device->path[chp].flags);
}

static inline void dasd_path_clear_nonpreferred(struct dasd_device *device,
                                                int chp)
{
        __clear_bit(DASD_PATH_NPP, &device->path[chp].flags);
}

static inline void dasd_path_preferred(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_PP, &device->path[chp].flags);
}

static inline int dasd_path_is_preferred(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_PP, &device->path[chp].flags);
}

static inline void dasd_path_clear_preferred(struct dasd_device *device,
                                             int chp)
{
        __clear_bit(DASD_PATH_PP, &device->path[chp].flags);
}

static inline void dasd_path_clear_oper(struct dasd_device *device, int chp)
{
        __clear_bit(DASD_PATH_OPERATIONAL, &device->path[chp].flags);
        device->opm &= ~(0x80 >> chp);
}

static inline void dasd_path_clear_cable(struct dasd_device *device, int chp)
{
        __clear_bit(DASD_PATH_MISCABLED, &device->path[chp].flags);
}

static inline void dasd_path_cuir(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_CUIR, &device->path[chp].flags);
}

static inline int dasd_path_is_cuir(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_CUIR, &device->path[chp].flags);
}

static inline void dasd_path_clear_cuir(struct dasd_device *device, int chp)
{
        __clear_bit(DASD_PATH_CUIR, &device->path[chp].flags);
}

static inline void dasd_path_ifcc(struct dasd_device *device, int chp)
{
        set_bit(DASD_PATH_IFCC, &device->path[chp].flags);
}

static inline int dasd_path_is_ifcc(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_IFCC, &device->path[chp].flags);
}

static inline void dasd_path_clear_ifcc(struct dasd_device *device, int chp)
{
        clear_bit(DASD_PATH_IFCC, &device->path[chp].flags);
}

static inline void dasd_path_clear_nohpf(struct dasd_device *device, int chp)
{
        __clear_bit(DASD_PATH_NOHPF, &device->path[chp].flags);
}

static inline void dasd_path_miscabled(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_MISCABLED, &device->path[chp].flags);
}

static inline int dasd_path_is_miscabled(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_MISCABLED, &device->path[chp].flags);
}

static inline void dasd_path_nohpf(struct dasd_device *device, int chp)
{
        __set_bit(DASD_PATH_NOHPF, &device->path[chp].flags);
}

static inline int dasd_path_is_nohpf(struct dasd_device *device, int chp)
{
        return test_bit(DASD_PATH_NOHPF, &device->path[chp].flags);
}

/*
 * get functions for path masks
 * will return a path masks for the given device
 */

static inline __u8 dasd_path_get_opm(struct dasd_device *device)
{
        return device->opm;
}

static inline __u8 dasd_path_get_tbvpm(struct dasd_device *device)
{
        int chp;
        __u8 tbvpm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_need_verify(device, chp))
                        tbvpm |= 0x80 >> chp;
        return tbvpm;
}

static inline __u8 dasd_path_get_nppm(struct dasd_device *device)
{
        int chp;
        __u8 npm = 0x00;

        for (chp = 0; chp < 8; chp++) {
                if (dasd_path_is_nonpreferred(device, chp))
                        npm |= 0x80 >> chp;
        }
        return npm;
}

static inline __u8 dasd_path_get_ppm(struct dasd_device *device)
{
        int chp;
        __u8 ppm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_preferred(device, chp))
                        ppm |= 0x80 >> chp;
        return ppm;
}

static inline __u8 dasd_path_get_cablepm(struct dasd_device *device)
{
        int chp;
        __u8 cablepm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_miscabled(device, chp))
                        cablepm |= 0x80 >> chp;
        return cablepm;
}

static inline __u8 dasd_path_get_cuirpm(struct dasd_device *device)
{
        int chp;
        __u8 cuirpm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_cuir(device, chp))
                        cuirpm |= 0x80 >> chp;
        return cuirpm;
}

static inline __u8 dasd_path_get_ifccpm(struct dasd_device *device)
{
        int chp;
        __u8 ifccpm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_ifcc(device, chp))
                        ifccpm |= 0x80 >> chp;
        return ifccpm;
}

static inline __u8 dasd_path_get_hpfpm(struct dasd_device *device)
{
        int chp;
        __u8 hpfpm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_nohpf(device, chp))
                        hpfpm |= 0x80 >> chp;
        return hpfpm;
}

/*
 * add functions for path masks
 * the existing path mask will be extended by the given path mask
 */
static inline void dasd_path_add_tbvpm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_verify(device, chp);
}

static inline __u8 dasd_path_get_notoperpm(struct dasd_device *device)
{
        int chp;
        __u8 nopm = 0x00;

        for (chp = 0; chp < 8; chp++)
                if (dasd_path_is_nohpf(device, chp) ||
                    dasd_path_is_ifcc(device, chp) ||
                    dasd_path_is_cuir(device, chp) ||
                    dasd_path_is_miscabled(device, chp))
                        nopm |= 0x80 >> chp;
        return nopm;
}

static inline void dasd_path_add_opm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp)) {
                        dasd_path_operational(device, chp);
                        /*
                         * if the path is used
                         * it should not be in one of the negative lists
                         */
                        dasd_path_clear_nohpf(device, chp);
                        dasd_path_clear_cuir(device, chp);
                        dasd_path_clear_cable(device, chp);
                        dasd_path_clear_ifcc(device, chp);
                }
}

static inline void dasd_path_add_cablepm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_miscabled(device, chp);
}

static inline void dasd_path_add_cuirpm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_cuir(device, chp);
}

static inline void dasd_path_add_ifccpm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_ifcc(device, chp);
}

static inline void dasd_path_add_nppm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_nonpreferred(device, chp);
}

static inline void dasd_path_add_nohpfpm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_nohpf(device, chp);
}

static inline void dasd_path_add_ppm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_preferred(device, chp);
}

/*
 * set functions for path masks
 * the existing path mask will be replaced by the given path mask
 */
static inline void dasd_path_set_tbvpm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                if (pm & (0x80 >> chp))
                        dasd_path_verify(device, chp);
                else
                        dasd_path_clear_verify(device, chp);
}

static inline void dasd_path_set_opm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++) {
                dasd_path_clear_oper(device, chp);
                if (pm & (0x80 >> chp)) {
                        dasd_path_operational(device, chp);
                        /*
                         * if the path is used
                         * it should not be in one of the negative lists
                         */
                        dasd_path_clear_nohpf(device, chp);
                        dasd_path_clear_cuir(device, chp);
                        dasd_path_clear_cable(device, chp);
                        dasd_path_clear_ifcc(device, chp);
                }
        }
}

/*
 * remove functions for path masks
 * the existing path mask will be cleared with the given path mask
 */
static inline void dasd_path_remove_opm(struct dasd_device *device, __u8 pm)
{
        int chp;

        for (chp = 0; chp < 8; chp++) {
                if (pm & (0x80 >> chp))
                        dasd_path_clear_oper(device, chp);
        }
}

/*
 * add the newly available path to the to be verified pm and remove it from
 * normal operation until it is verified
 */
static inline void dasd_path_available(struct dasd_device *device, int chp)
{
        dasd_path_clear_oper(device, chp);
        dasd_path_verify(device, chp);
}

static inline void dasd_path_notoper(struct dasd_device *device, int chp)
{
        dasd_path_clear_oper(device, chp);
        dasd_path_clear_preferred(device, chp);
        dasd_path_clear_nonpreferred(device, chp);
}

/*
 * remove all paths from normal operation
 */
static inline void dasd_path_no_path(struct dasd_device *device)
{
        int chp;

        for (chp = 0; chp < 8; chp++)
                dasd_path_notoper(device, chp);

        dasd_path_clear_all_verify(device);
}

/* end - path handling */

#endif                          /* DASD_H */