chp.c

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/*
 *    Copyright IBM Corp. 1999, 2010
 *    Author(s): Cornelia Huck ([email protected])
 *       Arnd Bergmann ([email protected])
 *       Peter Oberparleiter <[email protected]>
 */

#include <linux/bug.h>
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/chpid.h>
#include <asm/sclp.h>
#include <asm/crw.h>

#include "cio.h"
#include "css.h"
#include "ioasm.h"
#include "cio_debug.h"
#include "chp.h"

#define to_channelpath(device) container_of(device, struct channel_path, dev)
#define CHP_INFO_UPDATE_INTERVAL    1*HZ

enum cfg_task_t {
    cfg_none,
    cfg_configure,
    cfg_deconfigure
};

/* Map for pending configure tasks. */
static enum cfg_task_t chp_cfg_task[__MAX_CSSID + 1][__MAX_CHPID + 1];
static DEFINE_MUTEX(cfg_lock);
static int cfg_busy;

/* Map for channel-path status. */
static struct sclp_chp_info chp_info;
static DEFINE_MUTEX(info_lock);

/* Time after which channel-path status may be outdated. */
static unsigned long chp_info_expires;

/* Workqueue to perform pending configure tasks. */
static struct workqueue_struct *chp_wq;
static struct work_struct cfg_work;

/* Wait queue for configure completion events. */
static wait_queue_head_t cfg_wait_queue;

/* Set vary state for given chpid. */
static void set_chp_logically_online(struct chp_id chpid, int onoff)
{
    chpid_to_chp(chpid)->state = onoff;
}

/* On success return 0 if channel-path is varied offline, 1 if it is varied
 * online. Return -ENODEV if channel-path is not registered. */
int chp_get_status(struct chp_id chpid)
{
    return (chpid_to_chp(chpid) ? chpid_to_chp(chpid)->state : -ENODEV);
}

u8 chp_get_sch_opm(struct subchannel *sch)
{
    struct chp_id chpid;
    int opm;
    int i;

    opm = 0;
    chp_id_init(&chpid);
    for (i = 0; i < 8; i++) {
        opm <<= 1;
        chpid.id = sch->schib.pmcw.chpid[i];
        if (chp_get_status(chpid) != 0)
            opm |= 1;
    }
    return opm;
}
EXPORT_SYMBOL_GPL(chp_get_sch_opm);

int chp_is_registered(struct chp_id chpid)
{
    return chpid_to_chp(chpid) != NULL;
}

/*
 * Function: s390_vary_chpid
 * Varies the specified chpid online or offline
 */
static int s390_vary_chpid(struct chp_id chpid, int on)
{
    char dbf_text[15];
    int status;

    sprintf(dbf_text, on?"varyon%x.%02x":"varyoff%x.%02x", chpid.cssid,
        chpid.id);
    CIO_TRACE_EVENT(2, dbf_text);

    status = chp_get_status(chpid);
    if (!on && !status)
        return 0;

    set_chp_logically_online(chpid, on);
    chsc_chp_vary(chpid, on);
    return 0;
}

/*
 * Channel measurement related functions
 */
static ssize_t chp_measurement_chars_read(struct file *filp,
                      struct kobject *kobj,
                      struct bin_attribute *bin_attr,
                      char *buf, loff_t off, size_t count)
{
    struct channel_path *chp;
    struct device *device;

    device = container_of(kobj, struct device, kobj);
    chp = to_channelpath(device);
    if (!chp->cmg_chars)
        return 0;

    return memory_read_from_buffer(buf, count, &off,
                chp->cmg_chars, sizeof(struct cmg_chars));
}

static struct bin_attribute chp_measurement_chars_attr = {
    .attr = {
        .name = "measurement_chars",
        .mode = S_IRUSR,
    },
    .size = sizeof(struct cmg_chars),
    .read = chp_measurement_chars_read,
};

static void chp_measurement_copy_block(struct cmg_entry *buf,
                       struct channel_subsystem *css,
                       struct chp_id chpid)
{
    void *area;
    struct cmg_entry *entry, reference_buf;
    int idx;

    if (chpid.id < 128) {
        area = css->cub_addr1;
        idx = chpid.id;
    } else {
        area = css->cub_addr2;
        idx = chpid.id - 128;
    }
    entry = area + (idx * sizeof(struct cmg_entry));
    do {
        memcpy(buf, entry, sizeof(*entry));
        memcpy(&reference_buf, entry, sizeof(*entry));
    } while (reference_buf.values[0] != buf->values[0]);
}

static ssize_t chp_measurement_read(struct file *filp, struct kobject *kobj,
                    struct bin_attribute *bin_attr,
                    char *buf, loff_t off, size_t count)
{
    struct channel_path *chp;
    struct channel_subsystem *css;
    struct device *device;
    unsigned int size;

    device = container_of(kobj, struct device, kobj);
    chp = to_channelpath(device);
    css = to_css(chp->dev.parent);

    size = sizeof(struct cmg_entry);

    /* Only allow single reads. */
    if (off || count < size)
        return 0;
    chp_measurement_copy_block((struct cmg_entry *)buf, css, chp->chpid);
    count = size;
    return count;
}

static struct bin_attribute chp_measurement_attr = {
    .attr = {
        .name = "measurement",
        .mode = S_IRUSR,
    },
    .size = sizeof(struct cmg_entry),
    .read = chp_measurement_read,
};

void chp_remove_cmg_attr(struct channel_path *chp)
{
    device_remove_bin_file(&chp->dev, &chp_measurement_chars_attr);
    device_remove_bin_file(&chp->dev, &chp_measurement_attr);
}

int chp_add_cmg_attr(struct channel_path *chp)
{
    int ret;

    ret = device_create_bin_file(&chp->dev, &chp_measurement_chars_attr);
    if (ret)
        return ret;
    ret = device_create_bin_file(&chp->dev, &chp_measurement_attr);
    if (ret)
        device_remove_bin_file(&chp->dev, &chp_measurement_chars_attr);
    return ret;
}

/*
 * Files for the channel path entries.
 */
static ssize_t chp_status_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    struct channel_path *chp = to_channelpath(dev);
    int status;

    mutex_lock(&chp->lock);
    status = chp->state;
    mutex_unlock(&chp->lock);

    return status ? sprintf(buf, "online\n") : sprintf(buf, "offline\n");
}

static ssize_t chp_status_write(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t count)
{
    struct channel_path *cp = to_channelpath(dev);
    char cmd[10];
    int num_args;
    int error;

    num_args = sscanf(buf, "%5s", cmd);
    if (!num_args)
        return count;

    if (!strnicmp(cmd, "on", 2) || !strcmp(cmd, "1")) {
        mutex_lock(&cp->lock);
        error = s390_vary_chpid(cp->chpid, 1);
        mutex_unlock(&cp->lock);
    } else if (!strnicmp(cmd, "off", 3) || !strcmp(cmd, "0")) {
        mutex_lock(&cp->lock);
        error = s390_vary_chpid(cp->chpid, 0);
        mutex_unlock(&cp->lock);
    } else
        error = -EINVAL;

    return error < 0 ? error : count;
}

static DEVICE_ATTR(status, 0644, chp_status_show, chp_status_write);

static ssize_t chp_configure_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
{
    struct channel_path *cp;
    int status;

    cp = to_channelpath(dev);
    status = chp_info_get_status(cp->chpid);
    if (status < 0)
        return status;

    return snprintf(buf, PAGE_SIZE, "%d\n", status);
}

static int cfg_wait_idle(void);

static ssize_t chp_configure_write(struct device *dev,
                   struct device_attribute *attr,
                   const char *buf, size_t count)
{
    struct channel_path *cp;
    int val;
    char delim;

    if (sscanf(buf, "%d %c", &val, &delim) != 1)
        return -EINVAL;
    if (val != 0 && val != 1)
        return -EINVAL;
    cp = to_channelpath(dev);
    chp_cfg_schedule(cp->chpid, val);
    cfg_wait_idle();

    return count;
}

static DEVICE_ATTR(configure, 0644, chp_configure_show, chp_configure_write);

static ssize_t chp_type_show(struct device *dev, struct device_attribute *attr,
                 char *buf)
{
    struct channel_path *chp = to_channelpath(dev);
    u8 type;

    mutex_lock(&chp->lock);
    type = chp->desc.desc;
    mutex_unlock(&chp->lock);
    return sprintf(buf, "%x\n", type);
}

static DEVICE_ATTR(type, 0444, chp_type_show, NULL);

static ssize_t chp_cmg_show(struct device *dev, struct device_attribute *attr,
                char *buf)
{
    struct channel_path *chp = to_channelpath(dev);

    if (!chp)
        return 0;
    if (chp->cmg == -1) /* channel measurements not available */
        return sprintf(buf, "unknown\n");
    return sprintf(buf, "%x\n", chp->cmg);
}

static DEVICE_ATTR(cmg, 0444, chp_cmg_show, NULL);

static ssize_t chp_shared_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
    struct channel_path *chp = to_channelpath(dev);

    if (!chp)
        return 0;
    if (chp->shared == -1) /* channel measurements not available */
        return sprintf(buf, "unknown\n");
    return sprintf(buf, "%x\n", chp->shared);
}

static DEVICE_ATTR(shared, 0444, chp_shared_show, NULL);

static struct attribute *chp_attrs[] = {
    &dev_attr_status.attr,
    &dev_attr_configure.attr,
    &dev_attr_type.attr,
    &dev_attr_cmg.attr,
    &dev_attr_shared.attr,
    NULL,
};
static struct attribute_group chp_attr_group = {
    .attrs = chp_attrs,
};
static const struct attribute_group *chp_attr_groups[] = {
    &chp_attr_group,
    NULL,
};

static void chp_release(struct device *dev)
{
    struct channel_path *cp;

    cp = to_channelpath(dev);
    kfree(cp);
}

int chp_new(struct chp_id chpid)
{
    struct channel_path *chp;
    int ret;

    if (chp_is_registered(chpid))
        return 0;
    chp = kzalloc(sizeof(struct channel_path), GFP_KERNEL);
    if (!chp)
        return -ENOMEM;

    /* fill in status, etc. */
    chp->chpid = chpid;
    chp->state = 1;
    chp->dev.parent = &channel_subsystems[chpid.cssid]->device;
    chp->dev.groups = chp_attr_groups;
    chp->dev.release = chp_release;
    mutex_init(&chp->lock);

    /* Obtain channel path description and fill it in. */
    ret = chsc_determine_base_channel_path_desc(chpid, &chp->desc);
    if (ret)
        goto out_free;
    if ((chp->desc.flags & 0x80) == 0) {
        ret = -ENODEV;
        goto out_free;
    }
    /* Get channel-measurement characteristics. */
    if (css_chsc_characteristics.scmc && css_chsc_characteristics.secm) {
        ret = chsc_get_channel_measurement_chars(chp);
        if (ret)
            goto out_free;
    } else {
        chp->cmg = -1;
    }
    dev_set_name(&chp->dev, "chp%x.%02x", chpid.cssid, chpid.id);

    /* make it known to the system */
    ret = device_register(&chp->dev);
    if (ret) {
        CIO_MSG_EVENT(0, "Could not register chp%x.%02x: %d\n",
                  chpid.cssid, chpid.id, ret);
        put_device(&chp->dev);
        goto out;
    }
    mutex_lock(&channel_subsystems[chpid.cssid]->mutex);
    if (channel_subsystems[chpid.cssid]->cm_enabled) {
        ret = chp_add_cmg_attr(chp);
        if (ret) {
            device_unregister(&chp->dev);
            mutex_unlock(&channel_subsystems[chpid.cssid]->mutex);
            goto out;
        }
    }
    channel_subsystems[chpid.cssid]->chps[chpid.id] = chp;
    mutex_unlock(&channel_subsystems[chpid.cssid]->mutex);
    goto out;
out_free:
    kfree(chp);
out:
    return ret;
}

void *chp_get_chp_desc(struct chp_id chpid)
{
    struct channel_path *chp;
    struct channel_path_desc *desc;

    chp = chpid_to_chp(chpid);
    if (!chp)
        return NULL;
    desc = kmalloc(sizeof(struct channel_path_desc), GFP_KERNEL);
    if (!desc)
        return NULL;

    mutex_lock(&chp->lock);
    memcpy(desc, &chp->desc, sizeof(struct channel_path_desc));
    mutex_unlock(&chp->lock);
    return desc;
}

static void chp_process_crw(struct crw *crw0, struct crw *crw1,
                int overflow)
{
    struct chp_id chpid;

    if (overflow) {
        css_schedule_eval_all();
        return;
    }
    CIO_CRW_EVENT(2, "CRW reports slct=%d, oflw=%d, "
              "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
              crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
              crw0->erc, crw0->rsid);
    /*
     * Check for solicited machine checks. These are
     * created by reset channel path and need not be
     * handled here.
     */
    if (crw0->slct) {
        CIO_CRW_EVENT(2, "solicited machine check for "
                  "channel path %02X\n", crw0->rsid);
        return;
    }
    chp_id_init(&chpid);
    chpid.id = crw0->rsid;
    switch (crw0->erc) {
    case CRW_ERC_IPARM: /* Path has come. */
        if (!chp_is_registered(chpid))
            chp_new(chpid);
        chsc_chp_online(chpid);
        break;
    case CRW_ERC_PERRI: /* Path has gone. */
    case CRW_ERC_PERRN:
        chsc_chp_offline(chpid);
        break;
    default:
        CIO_CRW_EVENT(2, "Don't know how to handle erc=%x\n",
                  crw0->erc);
    }
}

int chp_ssd_get_mask(struct chsc_ssd_info *ssd, struct chp_link *link)
{
    int i;
    int mask;

    for (i = 0; i < 8; i++) {
        mask = 0x80 >> i;
        if (!(ssd->path_mask & mask))
            continue;
        if (!chp_id_is_equal(&ssd->chpid[i], &link->chpid))
            continue;
        if ((ssd->fla_valid_mask & mask) &&
            ((ssd->fla[i] & link->fla_mask) != link->fla))
            continue;
        return mask;
    }
    return 0;
}
EXPORT_SYMBOL_GPL(chp_ssd_get_mask);

static inline int info_bit_num(struct chp_id id)
{
    return id.id + id.cssid * (__MAX_CHPID + 1);
}

/* Force chp_info refresh on next call to info_validate(). */
static void info_expire(void)
{
    mutex_lock(&info_lock);
    chp_info_expires = jiffies - 1;
    mutex_unlock(&info_lock);
}

/* Ensure that chp_info is up-to-date. */
static int info_update(void)
{
    int rc;

    mutex_lock(&info_lock);
    rc = 0;
    if (time_after(jiffies, chp_info_expires)) {
        /* Data is too old, update. */
        rc = sclp_chp_read_info(&chp_info);
        chp_info_expires = jiffies + CHP_INFO_UPDATE_INTERVAL ;
    }
    mutex_unlock(&info_lock);

    return rc;
}

int chp_info_get_status(struct chp_id chpid)
{
    int rc;
    int bit;

    rc = info_update();
    if (rc)
        return rc;

    bit = info_bit_num(chpid);
    mutex_lock(&info_lock);
    if (!chp_test_bit(chp_info.recognized, bit))
        rc = CHP_STATUS_NOT_RECOGNIZED;
    else if (chp_test_bit(chp_info.configured, bit))
        rc = CHP_STATUS_CONFIGURED;
    else if (chp_test_bit(chp_info.standby, bit))
        rc = CHP_STATUS_STANDBY;
    else
        rc = CHP_STATUS_RESERVED;
    mutex_unlock(&info_lock);

    return rc;
}

/* Return configure task for chpid. */
static enum cfg_task_t cfg_get_task(struct chp_id chpid)
{
    return chp_cfg_task[chpid.cssid][chpid.id];
}

/* Set configure task for chpid. */
static void cfg_set_task(struct chp_id chpid, enum cfg_task_t cfg)
{
    chp_cfg_task[chpid.cssid][chpid.id] = cfg;
}

/* Perform one configure/deconfigure request. Reschedule work function until
 * last request. */
static void cfg_func(struct work_struct *work)
{
    struct chp_id chpid;
    enum cfg_task_t t;
    int rc;

    mutex_lock(&cfg_lock);
    t = cfg_none;
    chp_id_for_each(&chpid) {
        t = cfg_get_task(chpid);
        if (t != cfg_none) {
            cfg_set_task(chpid, cfg_none);
            break;
        }
    }
    mutex_unlock(&cfg_lock);

    switch (t) {
    case cfg_configure:
        rc = sclp_chp_configure(chpid);
        if (rc)
            CIO_MSG_EVENT(2, "chp: sclp_chp_configure(%x.%02x)="
                      "%d\n", chpid.cssid, chpid.id, rc);
        else {
            info_expire();
            chsc_chp_online(chpid);
        }
        break;
    case cfg_deconfigure:
        rc = sclp_chp_deconfigure(chpid);
        if (rc)
            CIO_MSG_EVENT(2, "chp: sclp_chp_deconfigure(%x.%02x)="
                      "%d\n", chpid.cssid, chpid.id, rc);
        else {
            info_expire();
            chsc_chp_offline(chpid);
        }
        break;
    case cfg_none:
        /* Get updated information after last change. */
        info_update();
        mutex_lock(&cfg_lock);
        cfg_busy = 0;
        mutex_unlock(&cfg_lock);
        wake_up_interruptible(&cfg_wait_queue);
        return;
    }
    queue_work(chp_wq, &cfg_work);
}

void chp_cfg_schedule(struct chp_id chpid, int configure)
{
    CIO_MSG_EVENT(2, "chp_cfg_sched%x.%02x=%d\n", chpid.cssid, chpid.id,
              configure);
    mutex_lock(&cfg_lock);
    cfg_set_task(chpid, configure ? cfg_configure : cfg_deconfigure);
    cfg_busy = 1;
    mutex_unlock(&cfg_lock);
    queue_work(chp_wq, &cfg_work);
}

void chp_cfg_cancel_deconfigure(struct chp_id chpid)
{
    CIO_MSG_EVENT(2, "chp_cfg_cancel:%x.%02x\n", chpid.cssid, chpid.id);
    mutex_lock(&cfg_lock);
    if (cfg_get_task(chpid) == cfg_deconfigure)
        cfg_set_task(chpid, cfg_none);
    mutex_unlock(&cfg_lock);
}

static int cfg_wait_idle(void)
{
    if (wait_event_interruptible(cfg_wait_queue, !cfg_busy))
        return -ERESTARTSYS;
    return 0;
}

static int __init chp_init(void)
{
    struct chp_id chpid;
    int ret;

    ret = crw_register_handler(CRW_RSC_CPATH, chp_process_crw);
    if (ret)
        return ret;
    chp_wq = create_singlethread_workqueue("cio_chp");
    if (!chp_wq) {
        crw_unregister_handler(CRW_RSC_CPATH);
        return -ENOMEM;
    }
    INIT_WORK(&cfg_work, cfg_func);
    init_waitqueue_head(&cfg_wait_queue);
    if (info_update())
        return 0;
    /* Register available channel-paths. */
    chp_id_for_each(&chpid) {
        if (chp_info_get_status(chpid) != CHP_STATUS_NOT_RECOGNIZED)
            chp_new(chpid);
    }

    return 0;
}

subsys_initcall(chp_init);