/*
 * Linux on zSeries Channel Measurement Facility support
 *
 * Copyright IBM Corp. 2000, 2006
 *
 * Authors: Arnd Bergmann <arndb@de.ibm.com>
 *          Cornelia Huck <cornelia.huck@de.ibm.com>
 *
 * original idea from Natarajan Krishnaswami <nkrishna@us.ibm.com>
 *
 * 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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define KMSG_COMPONENT "cio"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/bootmem.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/timex.h>        /* get_tod_clock() */

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/cmb.h>
#include <asm/div64.h>

#include "cio.h"
#include "css.h"
#include "device.h"
#include "ioasm.h"
#include "chsc.h"

/*
 * parameter to enable cmf during boot, possible uses are:
 *  "s390cmf" -- enable cmf and allocate 2 MB of ram so measuring can be
 *               used on any subchannel
 *  "s390cmf=<num>" -- enable cmf and allocate enough memory to measure
 *                     <num> subchannel, where <num> is an integer
 *                     between 1 and 65535, default is 1024
 */
#define ARGSTRING "s390cmf"

/* indices for READCMB */
enum cmb_index {
 /* basic and exended format: */
        cmb_ssch_rsch_count,
        cmb_sample_count,
        cmb_device_connect_time,
        cmb_function_pending_time,
        cmb_device_disconnect_time,
        cmb_control_unit_queuing_time,
        cmb_device_active_only_time,
 /* extended format only: */
        cmb_device_busy_time,
        cmb_initial_command_response_time,
};

/**
 * enum cmb_format - types of supported measurement block formats
 *
 * @CMF_BASIC:      traditional channel measurement blocks supported
 *                  by all machines that we run on
 * @CMF_EXTENDED:   improved format that was introduced with the z990
 *                  machine
 * @CMF_AUTODETECT: default: use extended format when running on a machine
 *                  supporting extended format, otherwise fall back to
 *                  basic format
 */
enum cmb_format {
        CMF_BASIC,
        CMF_EXTENDED,
        CMF_AUTODETECT = -1,
};

/*
 * format - actual format for all measurement blocks
 *
 * The format module parameter can be set to a value of 0 (zero)
 * or 1, indicating basic or extended format as described for
 * enum cmb_format.
 */
static int format = CMF_AUTODETECT;
module_param(format, bint, 0444);

/**
 * struct cmb_operations - functions to use depending on cmb_format
 *
 * Most of these functions operate on a struct ccw_device. There is only
 * one instance of struct cmb_operations because the format of the measurement
 * data is guaranteed to be the same for every ccw_device.
 *
 * @alloc:      allocate memory for a channel measurement block,
 *              either with the help of a special pool or with kmalloc
 * @free:       free memory allocated with @alloc
 * @set:        enable or disable measurement
 * @read:       read a measurement entry at an index
 * @readall:    read a measurement block in a common format
 * @reset:      clear the data in the associated measurement block and
 *              reset its time stamp
 */
struct cmb_operations {
        int  (*alloc)  (struct ccw_device *);
        void (*free)   (struct ccw_device *);
        int  (*set)    (struct ccw_device *, u32);
        u64  (*read)   (struct ccw_device *, int);
        int  (*readall)(struct ccw_device *, struct cmbdata *);
        void (*reset)  (struct ccw_device *);
/* private: */
        struct attribute_group *attr_group;
};
static struct cmb_operations *cmbops;

struct cmb_data {
        void *hw_block;   /* Pointer to block updated by hardware */
        void *last_block; /* Last changed block copied from hardware block */
        int size;         /* Size of hw_block and last_block */
        unsigned long long last_update;  /* when last_block was updated */
};

/*
 * Our user interface is designed in terms of nanoseconds,
 * while the hardware measures total times in its own
 * unit.
 */
static inline u64 time_to_nsec(u32 value)
{
        return ((u64)value) * 128000ull;
}

/*
 * Users are usually interested in average times,
 * not accumulated time.
 * This also helps us with atomicity problems
 * when reading sinlge values.
 */
static inline u64 time_to_avg_nsec(u32 value, u32 count)
{
        u64 ret;

        /* no samples yet, avoid division by 0 */
        if (count == 0)
                return 0;

        /* value comes in units of 128 µsec */
        ret = time_to_nsec(value);
        do_div(ret, count);

        return ret;
}

/*
 * Activate or deactivate the channel monitor. When area is NULL,
 * the monitor is deactivated. The channel monitor needs to
 * be active in order to measure subchannels, which also need
 * to be enabled.
 */
static inline void cmf_activate(void *area, unsigned int onoff)
{
        register void * __gpr2 asm("2");
        register long __gpr1 asm("1");

        __gpr2 = area;
        __gpr1 = onoff ? 2 : 0;
        /* activate channel measurement */
        asm("schm" : : "d" (__gpr2), "d" (__gpr1) );
}

static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
                     unsigned long address)
{
        struct subchannel *sch = to_subchannel(cdev->dev.parent);
        int ret;

        sch->config.mme = mme;
        sch->config.mbfc = mbfc;
        /* address can be either a block address or a block index */
        if (mbfc)
                sch->config.mba = address;
        else
                sch->config.mbi = address;

        ret = cio_commit_config(sch);
        if (!mme && ret == -ENODEV) {
                /*
                 * The task was to disable measurement block updates but
                 * the subchannel is already gone. Report success.
                 */
                ret = 0;
        }
        return ret;
}

struct set_schib_struct {
        u32 mme;
        int mbfc;
        unsigned long address;
        wait_queue_head_t wait;
        int ret;
        struct kref kref;
};

static void cmf_set_schib_release(struct kref *kref)
{
        struct set_schib_struct *set_data;

        set_data = container_of(kref, struct set_schib_struct, kref);
        kfree(set_data);
}

#define CMF_PENDING 1

static int set_schib_wait(struct ccw_device *cdev, u32 mme,
                                int mbfc, unsigned long address)
{
        struct set_schib_struct *set_data;
        int ret;

        spin_lock_irq(cdev->ccwlock);
        if (!cdev->private->cmb) {
                ret = -ENODEV;
                goto out;
        }
        set_data = kzalloc(sizeof(struct set_schib_struct), GFP_ATOMIC);
        if (!set_data) {
                ret = -ENOMEM;
                goto out;
        }
        init_waitqueue_head(&set_data->wait);
        kref_init(&set_data->kref);
        set_data->mme = mme;
        set_data->mbfc = mbfc;
        set_data->address = address;

        ret = set_schib(cdev, mme, mbfc, address);
        if (ret != -EBUSY)
                goto out_put;

        if (cdev->private->state != DEV_STATE_ONLINE) {
                /* if the device is not online, don't even try again */
                ret = -EBUSY;
                goto out_put;
        }

        cdev->private->state = DEV_STATE_CMFCHANGE;
        set_data->ret = CMF_PENDING;
        cdev->private->cmb_wait = set_data;

        spin_unlock_irq(cdev->ccwlock);
        if (wait_event_interruptible(set_data->wait,
                                     set_data->ret != CMF_PENDING)) {
                spin_lock_irq(cdev->ccwlock);
                if (set_data->ret == CMF_PENDING) {
                        set_data->ret = -ERESTARTSYS;
                        if (cdev->private->state == DEV_STATE_CMFCHANGE)
                                cdev->private->state = DEV_STATE_ONLINE;
                }
                spin_unlock_irq(cdev->ccwlock);
        }
        spin_lock_irq(cdev->ccwlock);
        cdev->private->cmb_wait = NULL;
        ret = set_data->ret;
out_put:
        kref_put(&set_data->kref, cmf_set_schib_release);
out:
        spin_unlock_irq(cdev->ccwlock);
        return ret;
}

void retry_set_schib(struct ccw_device *cdev)
{
        struct set_schib_struct *set_data;

        set_data = cdev->private->cmb_wait;
        if (!set_data) {
                WARN_ON(1);
                return;
        }
        kref_get(&set_data->kref);
        set_data->ret = set_schib(cdev, set_data->mme, set_data->mbfc,
                                  set_data->address);
        wake_up(&set_data->wait);
        kref_put(&set_data->kref, cmf_set_schib_release);
}

static int cmf_copy_block(struct ccw_device *cdev)
{
        struct subchannel *sch;
        void *reference_buf;
        void *hw_block;
        struct cmb_data *cmb_data;

        sch = to_subchannel(cdev->dev.parent);

        if (cio_update_schib(sch))
                return -ENODEV;

        if (scsw_fctl(&sch->schib.scsw) & SCSW_FCTL_START_FUNC) {
                /* Don't copy if a start function is in progress. */
                if ((!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_SUSPENDED)) &&
                    (scsw_actl(&sch->schib.scsw) &
                     (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)) &&
                    (!(scsw_stctl(&sch->schib.scsw) & SCSW_STCTL_SEC_STATUS)))
                        return -EBUSY;
        }
        cmb_data = cdev->private->cmb;
        hw_block = cmb_data->hw_block;
        if (!memcmp(cmb_data->last_block, hw_block, cmb_data->size))
                /* No need to copy. */
                return 0;
        reference_buf = kzalloc(cmb_data->size, GFP_ATOMIC);
        if (!reference_buf)
                return -ENOMEM;
        /* Ensure consistency of block copied from hardware. */
        do {
                memcpy(cmb_data->last_block, hw_block, cmb_data->size);
                memcpy(reference_buf, hw_block, cmb_data->size);
        } while (memcmp(cmb_data->last_block, reference_buf, cmb_data->size));
        cmb_data->last_update = get_tod_clock();
        kfree(reference_buf);
        return 0;
}

struct copy_block_struct {
        wait_queue_head_t wait;
        int ret;
        struct kref kref;
};

static void cmf_copy_block_release(struct kref *kref)
{
        struct copy_block_struct *copy_block;

        copy_block = container_of(kref, struct copy_block_struct, kref);
        kfree(copy_block);
}

static int cmf_cmb_copy_wait(struct ccw_device *cdev)
{
        struct copy_block_struct *copy_block;
        int ret;
        unsigned long flags;

        spin_lock_irqsave(cdev->ccwlock, flags);
        if (!cdev->private->cmb) {
                ret = -ENODEV;
                goto out;
        }
        copy_block = kzalloc(sizeof(struct copy_block_struct), GFP_ATOMIC);
        if (!copy_block) {
                ret = -ENOMEM;
                goto out;
        }
        init_waitqueue_head(&copy_block->wait);
        kref_init(&copy_block->kref);

        ret = cmf_copy_block(cdev);
        if (ret != -EBUSY)
                goto out_put;

        if (cdev->private->state != DEV_STATE_ONLINE) {
                ret = -EBUSY;
                goto out_put;
        }

        cdev->private->state = DEV_STATE_CMFUPDATE;
        copy_block->ret = CMF_PENDING;
        cdev->private->cmb_wait = copy_block;

        spin_unlock_irqrestore(cdev->ccwlock, flags);
        if (wait_event_interruptible(copy_block->wait,
                                     copy_block->ret != CMF_PENDING)) {
                spin_lock_irqsave(cdev->ccwlock, flags);
                if (copy_block->ret == CMF_PENDING) {
                        copy_block->ret = -ERESTARTSYS;
                        if (cdev->private->state == DEV_STATE_CMFUPDATE)
                                cdev->private->state = DEV_STATE_ONLINE;
                }
                spin_unlock_irqrestore(cdev->ccwlock, flags);
        }
        spin_lock_irqsave(cdev->ccwlock, flags);
        cdev->private->cmb_wait = NULL;
        ret = copy_block->ret;
out_put:
        kref_put(&copy_block->kref, cmf_copy_block_release);
out:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        return ret;
}

void cmf_retry_copy_block(struct ccw_device *cdev)
{
        struct copy_block_struct *copy_block;

        copy_block = cdev->private->cmb_wait;
        if (!copy_block) {
                WARN_ON(1);
                return;
        }
        kref_get(&copy_block->kref);
        copy_block->ret = cmf_copy_block(cdev);
        wake_up(&copy_block->wait);
        kref_put(&copy_block->kref, cmf_copy_block_release);
}

static void cmf_generic_reset(struct ccw_device *cdev)
{
        struct cmb_data *cmb_data;

        spin_lock_irq(cdev->ccwlock);
        cmb_data = cdev->private->cmb;
        if (cmb_data) {
                memset(cmb_data->last_block, 0, cmb_data->size);
                /*
                 * Need to reset hw block as well to make the hardware start
                 * from 0 again.
                 */
                memset(cmb_data->hw_block, 0, cmb_data->size);
                cmb_data->last_update = 0;
        }
        cdev->private->cmb_start_time = get_tod_clock();
        spin_unlock_irq(cdev->ccwlock);
}

/**
 * struct cmb_area - container for global cmb data
 *
 * @mem:        pointer to CMBs (only in basic measurement mode)
 * @list:       contains a linked list of all subchannels
 * @num_channels: number of channels to be measured
 * @lock:       protect concurrent access to @mem and @list
 */
struct cmb_area {
        struct cmb *mem;
        struct list_head list;
        int num_channels;
        spinlock_t lock;
};

static struct cmb_area cmb_area = {
        .lock = __SPIN_LOCK_UNLOCKED(cmb_area.lock),
        .list = LIST_HEAD_INIT(cmb_area.list),
        .num_channels  = 1024,
};

/* ****** old style CMB handling ********/

/*
 * Basic channel measurement blocks are allocated in one contiguous
 * block of memory, which can not be moved as long as any channel
 * is active. Therefore, a maximum number of subchannels needs to
 * be defined somewhere. This is a module parameter, defaulting to
 * a reasonable value of 1024, or 32 kb of memory.
 * Current kernels don't allow kmalloc with more than 128kb, so the
 * maximum is 4096.
 */

module_param_named(maxchannels, cmb_area.num_channels, uint, 0444);

/**
 * struct cmb - basic channel measurement block
 * @ssch_rsch_count: number of ssch and rsch
 * @sample_count: number of samples
 * @device_connect_time: time of device connect
 * @function_pending_time: time of function pending
 * @device_disconnect_time: time of device disconnect
 * @control_unit_queuing_time: time of control unit queuing
 * @device_active_only_time: time of device active only
 * @reserved: unused in basic measurement mode
 *
 * The measurement block as used by the hardware. The fields are described
 * further in z/Architecture Principles of Operation, chapter 17.
 *
 * The cmb area made up from these blocks must be a contiguous array and may
 * not be reallocated or freed.
 * Only one cmb area can be present in the system.
 */
struct cmb {
        u16 ssch_rsch_count;
        u16 sample_count;
        u32 device_connect_time;
        u32 function_pending_time;
        u32 device_disconnect_time;
        u32 control_unit_queuing_time;
        u32 device_active_only_time;
        u32 reserved[2];
};

/*
 * Insert a single device into the cmb_area list.
 * Called with cmb_area.lock held from alloc_cmb.
 */
static int alloc_cmb_single(struct ccw_device *cdev,
                            struct cmb_data *cmb_data)
{
        struct cmb *cmb;
        struct ccw_device_private *node;
        int ret;

        spin_lock_irq(cdev->ccwlock);
        if (!list_empty(&cdev->private->cmb_list)) {
                ret = -EBUSY;
                goto out;
        }

        /*
         * Find first unused cmb in cmb_area.mem.
         * This is a little tricky: cmb_area.list
         * remains sorted by ->cmb->hw_data pointers.
         */
        cmb = cmb_area.mem;
        list_for_each_entry(node, &cmb_area.list, cmb_list) {
                struct cmb_data *data;
                data = node->cmb;
                if ((struct cmb*)data->hw_block > cmb)
                        break;
                cmb++;
        }
        if (cmb - cmb_area.mem >= cmb_area.num_channels) {
                ret = -ENOMEM;
                goto out;
        }

        /* insert new cmb */
        list_add_tail(&cdev->private->cmb_list, &node->cmb_list);
        cmb_data->hw_block = cmb;
        cdev->private->cmb = cmb_data;
        ret = 0;
out:
        spin_unlock_irq(cdev->ccwlock);
        return ret;
}

static int alloc_cmb(struct ccw_device *cdev)
{
        int ret;
        struct cmb *mem;
        ssize_t size;
        struct cmb_data *cmb_data;

        /* Allocate private cmb_data. */
        cmb_data = kzalloc(sizeof(struct cmb_data), GFP_KERNEL);
        if (!cmb_data)
                return -ENOMEM;

        cmb_data->last_block = kzalloc(sizeof(struct cmb), GFP_KERNEL);
        if (!cmb_data->last_block) {
                kfree(cmb_data);
                return -ENOMEM;
        }
        cmb_data->size = sizeof(struct cmb);
        spin_lock(&cmb_area.lock);

        if (!cmb_area.mem) {
                /* there is no user yet, so we need a new area */
                size = sizeof(struct cmb) * cmb_area.num_channels;
                WARN_ON(!list_empty(&cmb_area.list));

                spin_unlock(&cmb_area.lock);
                mem = (void*)__get_free_pages(GFP_KERNEL | GFP_DMA,
                                 get_order(size));
                spin_lock(&cmb_area.lock);

                if (cmb_area.mem) {
                        /* ok, another thread was faster */
                        free_pages((unsigned long)mem, get_order(size));
                } else if (!mem) {
                        /* no luck */
                        ret = -ENOMEM;
                        goto out;
                } else {
                        /* everything ok */
                        memset(mem, 0, size);
                        cmb_area.mem = mem;
                        cmf_activate(cmb_area.mem, 1);
                }
        }

        /* do the actual allocation */
        ret = alloc_cmb_single(cdev, cmb_data);
out:
        spin_unlock(&cmb_area.lock);
        if (ret) {
                kfree(cmb_data->last_block);
                kfree(cmb_data);
        }
        return ret;
}

static void free_cmb(struct ccw_device *cdev)
{
        struct ccw_device_private *priv;
        struct cmb_data *cmb_data;

        spin_lock(&cmb_area.lock);
        spin_lock_irq(cdev->ccwlock);

        priv = cdev->private;
        cmb_data = priv->cmb;
        priv->cmb = NULL;
        if (cmb_data)
                kfree(cmb_data->last_block);
        kfree(cmb_data);
        list_del_init(&priv->cmb_list);

        if (list_empty(&cmb_area.list)) {
                ssize_t size;
                size = sizeof(struct cmb) * cmb_area.num_channels;
                cmf_activate(NULL, 0);
                free_pages((unsigned long)cmb_area.mem, get_order(size));
                cmb_area.mem = NULL;
        }
        spin_unlock_irq(cdev->ccwlock);
        spin_unlock(&cmb_area.lock);
}

static int set_cmb(struct ccw_device *cdev, u32 mme)
{
        u16 offset;
        struct cmb_data *cmb_data;
        unsigned long flags;

        spin_lock_irqsave(cdev->ccwlock, flags);
        if (!cdev->private->cmb) {
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                return -EINVAL;
        }
        cmb_data = cdev->private->cmb;
        offset = mme ? (struct cmb *)cmb_data->hw_block - cmb_area.mem : 0;
        spin_unlock_irqrestore(cdev->ccwlock, flags);

        return set_schib_wait(cdev, mme, 0, offset);
}

static u64 read_cmb(struct ccw_device *cdev, int index)
{
        struct cmb *cmb;
        u32 val;
        int ret;
        unsigned long flags;

        ret = cmf_cmb_copy_wait(cdev);
        if (ret < 0)
                return 0;

        spin_lock_irqsave(cdev->ccwlock, flags);
        if (!cdev->private->cmb) {
                ret = 0;
                goto out;
        }
        cmb = ((struct cmb_data *)cdev->private->cmb)->last_block;

        switch (index) {
        case cmb_ssch_rsch_count:
                ret = cmb->ssch_rsch_count;
                goto out;
        case cmb_sample_count:
                ret = cmb->sample_count;
                goto out;
        case cmb_device_connect_time:
                val = cmb->device_connect_time;
                break;
        case cmb_function_pending_time:
                val = cmb->function_pending_time;
                break;
        case cmb_device_disconnect_time:
                val = cmb->device_disconnect_time;
                break;
        case cmb_control_unit_queuing_time:
                val = cmb->control_unit_queuing_time;
                break;
        case cmb_device_active_only_time:
                val = cmb->device_active_only_time;
                break;
        default:
                ret = 0;
                goto out;
        }
        ret = time_to_avg_nsec(val, cmb->sample_count);
out:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        return ret;
}

static int readall_cmb(struct ccw_device *cdev, struct cmbdata *data)
{
        struct cmb *cmb;
        struct cmb_data *cmb_data;
        u64 time;
        unsigned long flags;
        int ret;

        ret = cmf_cmb_copy_wait(cdev);
        if (ret < 0)
                return ret;
        spin_lock_irqsave(cdev->ccwlock, flags);
        cmb_data = cdev->private->cmb;
        if (!cmb_data) {
                ret = -ENODEV;
                goto out;
        }
        if (cmb_data->last_update == 0) {
                ret = -EAGAIN;
                goto out;
        }
        cmb = cmb_data->last_block;
        time = cmb_data->last_update - cdev->private->cmb_start_time;

        memset(data, 0, sizeof(struct cmbdata));

        /* we only know values before device_busy_time */
        data->size = offsetof(struct cmbdata, device_busy_time);

        /* convert to nanoseconds */
        data->elapsed_time = (time * 1000) >> 12;

        /* copy data to new structure */
        data->ssch_rsch_count = cmb->ssch_rsch_count;
        data->sample_count = cmb->sample_count;

        /* time fields are converted to nanoseconds while copying */
        data->device_connect_time = time_to_nsec(cmb->device_connect_time);
        data->function_pending_time = time_to_nsec(cmb->function_pending_time);
        data->device_disconnect_time =
                time_to_nsec(cmb->device_disconnect_time);
        data->control_unit_queuing_time
                = time_to_nsec(cmb->control_unit_queuing_time);
        data->device_active_only_time
                = time_to_nsec(cmb->device_active_only_time);
        ret = 0;
out:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        return ret;
}

static void reset_cmb(struct ccw_device *cdev)
{
        cmf_generic_reset(cdev);
}

static struct attribute_group cmf_attr_group;

static struct cmb_operations cmbops_basic = {
        .alloc  = alloc_cmb,
        .free   = free_cmb,
        .set    = set_cmb,
        .read   = read_cmb,
        .readall    = readall_cmb,
        .reset      = reset_cmb,
        .attr_group = &cmf_attr_group,
};

/* ******** extended cmb handling ********/

/**
 * struct cmbe - extended channel measurement block
 * @ssch_rsch_count: number of ssch and rsch
 * @sample_count: number of samples
 * @device_connect_time: time of device connect
 * @function_pending_time: time of function pending
 * @device_disconnect_time: time of device disconnect
 * @control_unit_queuing_time: time of control unit queuing
 * @device_active_only_time: time of device active only
 * @device_busy_time: time of device busy
 * @initial_command_response_time: initial command response time
 * @reserved: unused
 *
 * The measurement block as used by the hardware. May be in any 64 bit physical
 * location.
 * The fields are described further in z/Architecture Principles of Operation,
 * third edition, chapter 17.
 */
struct cmbe {
        u32 ssch_rsch_count;
        u32 sample_count;
        u32 device_connect_time;
        u32 function_pending_time;
        u32 device_disconnect_time;
        u32 control_unit_queuing_time;
        u32 device_active_only_time;
        u32 device_busy_time;
        u32 initial_command_response_time;
        u32 reserved[7];
} __packed __aligned(64);

static struct kmem_cache *cmbe_cache;

static int alloc_cmbe(struct ccw_device *cdev)
{
        struct cmb_data *cmb_data;
        struct cmbe *cmbe;
        int ret = -ENOMEM;

        cmbe = kmem_cache_zalloc(cmbe_cache, GFP_KERNEL);
        if (!cmbe)
                return ret;

        cmb_data = kzalloc(sizeof(*cmb_data), GFP_KERNEL);
        if (!cmb_data)
                goto out_free;

        cmb_data->last_block = kzalloc(sizeof(struct cmbe), GFP_KERNEL);
        if (!cmb_data->last_block)
                goto out_free;

        cmb_data->size = sizeof(*cmbe);
        cmb_data->hw_block = cmbe;

        spin_lock(&cmb_area.lock);
        spin_lock_irq(cdev->ccwlock);
        if (cdev->private->cmb)
                goto out_unlock;

        cdev->private->cmb = cmb_data;

        /* activate global measurement if this is the first channel */
        if (list_empty(&cmb_area.list))
                cmf_activate(NULL, 1);
        list_add_tail(&cdev->private->cmb_list, &cmb_area.list);

        spin_unlock_irq(cdev->ccwlock);
        spin_unlock(&cmb_area.lock);
        return 0;

out_unlock:
        spin_unlock_irq(cdev->ccwlock);
        spin_unlock(&cmb_area.lock);
        ret = -EBUSY;
out_free:
        if (cmb_data)
                kfree(cmb_data->last_block);
        kfree(cmb_data);
        kmem_cache_free(cmbe_cache, cmbe);

        return ret;
}

static void free_cmbe(struct ccw_device *cdev)
{
        struct cmb_data *cmb_data;

        spin_lock(&cmb_area.lock);
        spin_lock_irq(cdev->ccwlock);
        cmb_data = cdev->private->cmb;
        cdev->private->cmb = NULL;
        if (cmb_data) {
                kfree(cmb_data->last_block);
                kmem_cache_free(cmbe_cache, cmb_data->hw_block);
        }
        kfree(cmb_data);

        /* deactivate global measurement if this is the last channel */
        list_del_init(&cdev->private->cmb_list);
        if (list_empty(&cmb_area.list))
                cmf_activate(NULL, 0);
        spin_unlock_irq(cdev->ccwlock);
        spin_unlock(&cmb_area.lock);
}

static int set_cmbe(struct ccw_device *cdev, u32 mme)
{
        unsigned long mba;
        struct cmb_data *cmb_data;
        unsigned long flags;

        spin_lock_irqsave(cdev->ccwlock, flags);
        if (!cdev->private->cmb) {
                spin_unlock_irqrestore(cdev->ccwlock, flags);
                return -EINVAL;
        }
        cmb_data = cdev->private->cmb;
        mba = mme ? (unsigned long) cmb_data->hw_block : 0;
        spin_unlock_irqrestore(cdev->ccwlock, flags);

        return set_schib_wait(cdev, mme, 1, mba);
}


static u64 read_cmbe(struct ccw_device *cdev, int index)
{
        struct cmbe *cmb;
        struct cmb_data *cmb_data;
        u32 val;
        int ret;
        unsigned long flags;

        ret = cmf_cmb_copy_wait(cdev);
        if (ret < 0)
                return 0;

        spin_lock_irqsave(cdev->ccwlock, flags);
        cmb_data = cdev->private->cmb;
        if (!cmb_data) {
                ret = 0;
                goto out;
        }
        cmb = cmb_data->last_block;

        switch (index) {
        case cmb_ssch_rsch_count:
                ret = cmb->ssch_rsch_count;
                goto out;
        case cmb_sample_count:
                ret = cmb->sample_count;
                goto out;
        case cmb_device_connect_time:
                val = cmb->device_connect_time;
                break;
        case cmb_function_pending_time:
                val = cmb->function_pending_time;
                break;
        case cmb_device_disconnect_time:
                val = cmb->device_disconnect_time;
                break;
        case cmb_control_unit_queuing_time:
                val = cmb->control_unit_queuing_time;
                break;
        case cmb_device_active_only_time:
                val = cmb->device_active_only_time;
                break;
        case cmb_device_busy_time:
                val = cmb->device_busy_time;
                break;
        case cmb_initial_command_response_time:
                val = cmb->initial_command_response_time;
                break;
        default:
                ret = 0;
                goto out;
        }
        ret = time_to_avg_nsec(val, cmb->sample_count);
out:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        return ret;
}

static int readall_cmbe(struct ccw_device *cdev, struct cmbdata *data)
{
        struct cmbe *cmb;
        struct cmb_data *cmb_data;
        u64 time;
        unsigned long flags;
        int ret;

        ret = cmf_cmb_copy_wait(cdev);
        if (ret < 0)
                return ret;
        spin_lock_irqsave(cdev->ccwlock, flags);
        cmb_data = cdev->private->cmb;
        if (!cmb_data) {
                ret = -ENODEV;
                goto out;
        }
        if (cmb_data->last_update == 0) {
                ret = -EAGAIN;
                goto out;
        }
        time = cmb_data->last_update - cdev->private->cmb_start_time;

        memset (data, 0, sizeof(struct cmbdata));

        /* we only know values before device_busy_time */
        data->size = offsetof(struct cmbdata, device_busy_time);

        /* conver to nanoseconds */
        data->elapsed_time = (time * 1000) >> 12;

        cmb = cmb_data->last_block;
        /* copy data to new structure */
        data->ssch_rsch_count = cmb->ssch_rsch_count;
        data->sample_count = cmb->sample_count;

        /* time fields are converted to nanoseconds while copying */
        data->device_connect_time = time_to_nsec(cmb->device_connect_time);
        data->function_pending_time = time_to_nsec(cmb->function_pending_time);
        data->device_disconnect_time =
                time_to_nsec(cmb->device_disconnect_time);
        data->control_unit_queuing_time
                = time_to_nsec(cmb->control_unit_queuing_time);
        data->device_active_only_time
                = time_to_nsec(cmb->device_active_only_time);
        data->device_busy_time = time_to_nsec(cmb->device_busy_time);
        data->initial_command_response_time
                = time_to_nsec(cmb->initial_command_response_time);

        ret = 0;
out:
        spin_unlock_irqrestore(cdev->ccwlock, flags);
        return ret;
}

static void reset_cmbe(struct ccw_device *cdev)
{
        cmf_generic_reset(cdev);
}

static struct attribute_group cmf_attr_group_ext;

static struct cmb_operations cmbops_extended = {
        .alloc      = alloc_cmbe,
        .free       = free_cmbe,
        .set        = set_cmbe,
        .read       = read_cmbe,
        .readall    = readall_cmbe,
        .reset      = reset_cmbe,
        .attr_group = &cmf_attr_group_ext,
};

static ssize_t cmb_show_attr(struct device *dev, char *buf, enum cmb_index idx)
{
        return sprintf(buf, "%lld\n",
                (unsigned long long) cmf_read(to_ccwdev(dev), idx));
}

static ssize_t cmb_show_avg_sample_interval(struct device *dev,
                                            struct device_attribute *attr,
                                            char *buf)
{
        struct ccw_device *cdev;
        long interval;
        unsigned long count;
        struct cmb_data *cmb_data;

        cdev = to_ccwdev(dev);
        count = cmf_read(cdev, cmb_sample_count);
        spin_lock_irq(cdev->ccwlock);
        cmb_data = cdev->private->cmb;
        if (count) {
                interval = cmb_data->last_update -
                        cdev->private->cmb_start_time;
                interval = (interval * 1000) >> 12;
                interval /= count;
        } else
                interval = -1;
        spin_unlock_irq(cdev->ccwlock);
        return sprintf(buf, "%ld\n", interval);
}

static ssize_t cmb_show_avg_utilization(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct cmbdata data;
        u64 utilization;
        unsigned long t, u;
        int ret;

        ret = cmf_readall(to_ccwdev(dev), &data);
        if (ret == -EAGAIN || ret == -ENODEV)
                /* No data (yet/currently) available to use for calculation. */
                return sprintf(buf, "n/a\n");
        else if (ret)
                return ret;

        utilization = data.device_connect_time +
                      data.function_pending_time +
                      data.device_disconnect_time;

        /* shift to avoid long long division */
        while (-1ul < (data.elapsed_time | utilization)) {
                utilization >>= 8;
                data.elapsed_time >>= 8;
        }

        /* calculate value in 0.1 percent units */
        t = (unsigned long) data.elapsed_time / 1000;
        u = (unsigned long) utilization / t;

        return sprintf(buf, "%02ld.%01ld%%\n", u/ 10, u - (u/ 10) * 10);
}

#define cmf_attr(name) \
static ssize_t show_##name(struct device *dev, \
                           struct device_attribute *attr, char *buf)    \
{ return cmb_show_attr((dev), buf, cmb_##name); } \
static DEVICE_ATTR(name, 0444, show_##name, NULL);

#define cmf_attr_avg(name) \
static ssize_t show_avg_##name(struct device *dev, \
                               struct device_attribute *attr, char *buf) \
{ return cmb_show_attr((dev), buf, cmb_##name); } \
static DEVICE_ATTR(avg_##name, 0444, show_avg_##name, NULL);

cmf_attr(ssch_rsch_count);
cmf_attr(sample_count);
cmf_attr_avg(device_connect_time);
cmf_attr_avg(function_pending_time);
cmf_attr_avg(device_disconnect_time);
cmf_attr_avg(control_unit_queuing_time);
cmf_attr_avg(device_active_only_time);
cmf_attr_avg(device_busy_time);
cmf_attr_avg(initial_command_response_time);

static DEVICE_ATTR(avg_sample_interval, 0444, cmb_show_avg_sample_interval,
                   NULL);
static DEVICE_ATTR(avg_utilization, 0444, cmb_show_avg_utilization, NULL);

static struct attribute *cmf_attributes[] = {
        &dev_attr_avg_sample_interval.attr,
        &dev_attr_avg_utilization.attr,
        &dev_attr_ssch_rsch_count.attr,
        &dev_attr_sample_count.attr,
        &dev_attr_avg_device_connect_time.attr,
        &dev_attr_avg_function_pending_time.attr,
        &dev_attr_avg_device_disconnect_time.attr,
        &dev_attr_avg_control_unit_queuing_time.attr,
        &dev_attr_avg_device_active_only_time.attr,
        NULL,
};

static struct attribute_group cmf_attr_group = {
        .name  = "cmf",
        .attrs = cmf_attributes,
};

static struct attribute *cmf_attributes_ext[] = {
        &dev_attr_avg_sample_interval.attr,
        &dev_attr_avg_utilization.attr,
        &dev_attr_ssch_rsch_count.attr,
        &dev_attr_sample_count.attr,
        &dev_attr_avg_device_connect_time.attr,
        &dev_attr_avg_function_pending_time.attr,
        &dev_attr_avg_device_disconnect_time.attr,
        &dev_attr_avg_control_unit_queuing_time.attr,
        &dev_attr_avg_device_active_only_time.attr,
        &dev_attr_avg_device_busy_time.attr,
        &dev_attr_avg_initial_command_response_time.attr,
        NULL,
};

static struct attribute_group cmf_attr_group_ext = {
        .name  = "cmf",
        .attrs = cmf_attributes_ext,
};

static ssize_t cmb_enable_show(struct device *dev,
                               struct device_attribute *attr,
                               char *buf)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        int enabled;

        spin_lock_irq(cdev->ccwlock);
        enabled = !!cdev->private->cmb;
        spin_unlock_irq(cdev->ccwlock);

        return sprintf(buf, "%d\n", enabled);
}

static ssize_t cmb_enable_store(struct device *dev,
                                struct device_attribute *attr, const char *buf,
                                size_t c)
{
        struct ccw_device *cdev = to_ccwdev(dev);
        unsigned long val;
        int ret;

        ret = kstrtoul(buf, 16, &val);
        if (ret)
                return ret;

        switch (val) {
        case 0:
                ret = disable_cmf(cdev);
                break;
        case 1:
                ret = enable_cmf(cdev);
                break;
        default:
                ret = -EINVAL;
        }

        return ret ? ret : c;
}
DEVICE_ATTR_RW(cmb_enable);

int ccw_set_cmf(struct ccw_device *cdev, int enable)
{
        return cmbops->set(cdev, enable ? 2 : 0);
}

/**
 * enable_cmf() - switch on the channel measurement for a specific device
 *  @cdev:      The ccw device to be enabled
 *
 *  Returns %0 for success or a negative error value.
 *
 *  Context:
 *    non-atomic
 */
int enable_cmf(struct ccw_device *cdev)
{
        int ret;

        device_lock(&cdev->dev);
        get_device(&cdev->dev);
        ret = cmbops->alloc(cdev);
        if (ret)
                goto out;
        cmbops->reset(cdev);
        ret = sysfs_create_group(&cdev->dev.kobj, cmbops->attr_group);
        if (ret) {
                cmbops->free(cdev);
                goto out;
        }
        ret = cmbops->set(cdev, 2);
        if (ret) {
                sysfs_remove_group(&cdev->dev.kobj, cmbops->attr_group);
                cmbops->free(cdev);
        }
out:
        if (ret)
                put_device(&cdev->dev);

        device_unlock(&cdev->dev);
        return ret;
}

/**
 * __disable_cmf() - switch off the channel measurement for a specific device
 *  @cdev:      The ccw device to be disabled
 *
 *  Returns %0 for success or a negative error value.
 *
 *  Context:
 *    non-atomic, device_lock() held.
 */
int __disable_cmf(struct ccw_device *cdev)
{
        int ret;

        ret = cmbops->set(cdev, 0);
        if (ret)
                return ret;

        sysfs_remove_group(&cdev->dev.kobj, cmbops->attr_group);
        cmbops->free(cdev);
        put_device(&cdev->dev);

        return ret;
}

/**
 * disable_cmf() - switch off the channel measurement for a specific device
 *  @cdev:      The ccw device to be disabled
 *
 *  Returns %0 for success or a negative error value.
 *
 *  Context:
 *    non-atomic
 */
int disable_cmf(struct ccw_device *cdev)
{
        int ret;

        device_lock(&cdev->dev);
        ret = __disable_cmf(cdev);
        device_unlock(&cdev->dev);

        return ret;
}

/**
 * cmf_read() - read one value from the current channel measurement block
 * @cdev:       the channel to be read
 * @index:      the index of the value to be read
 *
 * Returns the value read or %0 if the value cannot be read.
 *
 *  Context:
 *    any
 */
u64 cmf_read(struct ccw_device *cdev, int index)
{
        return cmbops->read(cdev, index);
}

/**
 * cmf_readall() - read the current channel measurement block
 * @cdev:       the channel to be read
 * @data:       a pointer to a data block that will be filled
 *
 * Returns %0 on success, a negative error value otherwise.
 *
 *  Context:
 *    any
 */
int cmf_readall(struct ccw_device *cdev, struct cmbdata *data)
{
        return cmbops->readall(cdev, data);
}

/* Reenable cmf when a disconnected device becomes available again. */
int cmf_reenable(struct ccw_device *cdev)
{
        cmbops->reset(cdev);
        return cmbops->set(cdev, 2);
}

/**
 * cmf_reactivate() - reactivate measurement block updates
 *
 * Use this during resume from hibernate.
 */
void cmf_reactivate(void)
{
        spin_lock(&cmb_area.lock);
        if (!list_empty(&cmb_area.list))
                cmf_activate(cmb_area.mem, 1);
        spin_unlock(&cmb_area.lock);
}

static int __init init_cmbe(void)
{
        cmbe_cache = kmem_cache_create("cmbe_cache", sizeof(struct cmbe),
                                       __alignof__(struct cmbe), 0, NULL);

        return cmbe_cache ? 0 : -ENOMEM;
}

static int __init init_cmf(void)
{
        char *format_string;
        char *detect_string;
        int ret;

        /*
         * If the user did not give a parameter, see if we are running on a
         * machine supporting extended measurement blocks, otherwise fall back
         * to basic mode.
         */
        if (format == CMF_AUTODETECT) {
                if (!css_general_characteristics.ext_mb) {
                        format = CMF_BASIC;
                } else {
                        format = CMF_EXTENDED;
                }
                detect_string = "autodetected";
        } else {
                detect_string = "parameter";
        }

        switch (format) {
        case CMF_BASIC:
                format_string = "basic";
                cmbops = &cmbops_basic;
                break;
        case CMF_EXTENDED:
                format_string = "extended";
                cmbops = &cmbops_extended;

                ret = init_cmbe();
                if (ret)
                        return ret;
                break;
        default:
                return -EINVAL;
        }
        pr_info("Channel measurement facility initialized using format "
                "%s (mode %s)\n", format_string, detect_string);
        return 0;
}
module_init(init_cmf);


MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("channel measurement facility base driver\n"
                   "Copyright IBM Corp. 2003\n");

EXPORT_SYMBOL_GPL(enable_cmf);
EXPORT_SYMBOL_GPL(disable_cmf);
EXPORT_SYMBOL_GPL(cmf_read);
EXPORT_SYMBOL_GPL(cmf_readall);