ccwgroup.c

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/*
 *  bus driver for ccwgroup
 *
 *  Copyright IBM Corp. 2002, 2012
 *
 *  Author(s): Arnd Bergmann ([email protected])
 *         Cornelia Huck ([email protected])
 */
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/ctype.h>
#include <linux/dcache.h>

#include <asm/cio.h>
#include <asm/ccwdev.h>
#include <asm/ccwgroup.h>

#include "device.h"

#define CCW_BUS_ID_SIZE     10

/* In Linux 2.4, we had a channel device layer called "chandev"
 * that did all sorts of obscure stuff for networking devices.
 * This is another driver that serves as a replacement for just
 * one of its functions, namely the translation of single subchannels
 * to devices that use multiple subchannels.
 */

static struct bus_type ccwgroup_bus_type;

static void __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
{
    int i;
    char str[8];

    for (i = 0; i < gdev->count; i++) {
        sprintf(str, "cdev%d", i);
        sysfs_remove_link(&gdev->dev.kobj, str);
        sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
    }
}

/*
 * Remove references from ccw devices to ccw group device and from
 * ccw group device to ccw devices.
 */
static void __ccwgroup_remove_cdev_refs(struct ccwgroup_device *gdev)
{
    struct ccw_device *cdev;
    int i;

    for (i = 0; i < gdev->count; i++) {
        cdev = gdev->cdev[i];
        if (!cdev)
            continue;
        spin_lock_irq(cdev->ccwlock);
        dev_set_drvdata(&cdev->dev, NULL);
        spin_unlock_irq(cdev->ccwlock);
        gdev->cdev[i] = NULL;
        put_device(&cdev->dev);
    }
}

static int ccwgroup_set_online(struct ccwgroup_device *gdev)
{
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
    int ret = 0;

    if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
        return -EAGAIN;
    if (gdev->state == CCWGROUP_ONLINE)
        goto out;
    if (gdrv->set_online)
        ret = gdrv->set_online(gdev);
    if (ret)
        goto out;

    gdev->state = CCWGROUP_ONLINE;
out:
    atomic_set(&gdev->onoff, 0);
    return ret;
}

static int ccwgroup_set_offline(struct ccwgroup_device *gdev)
{
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
    int ret = 0;

    if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
        return -EAGAIN;
    if (gdev->state == CCWGROUP_OFFLINE)
        goto out;
    if (gdrv->set_offline)
        ret = gdrv->set_offline(gdev);
    if (ret)
        goto out;

    gdev->state = CCWGROUP_OFFLINE;
out:
    atomic_set(&gdev->onoff, 0);
    return ret;
}

static ssize_t ccwgroup_online_store(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
    unsigned long value;
    int ret;

    if (!dev->driver)
        return -EINVAL;
    if (!try_module_get(gdrv->driver.owner))
        return -EINVAL;

    ret = strict_strtoul(buf, 0, &value);
    if (ret)
        goto out;

    if (value == 1)
        ret = ccwgroup_set_online(gdev);
    else if (value == 0)
        ret = ccwgroup_set_offline(gdev);
    else
        ret = -EINVAL;
out:
    module_put(gdrv->driver.owner);
    return (ret == 0) ? count : ret;
}

static ssize_t ccwgroup_online_show(struct device *dev,
                    struct device_attribute *attr,
                    char *buf)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    int online;

    online = (gdev->state == CCWGROUP_ONLINE) ? 1 : 0;

    return scnprintf(buf, PAGE_SIZE, "%d\n", online);
}

/*
 * Provide an 'ungroup' attribute so the user can remove group devices no
 * longer needed or accidentially created. Saves memory :)
 */
static void ccwgroup_ungroup_callback(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);

    mutex_lock(&gdev->reg_mutex);
    if (device_is_registered(&gdev->dev)) {
        __ccwgroup_remove_symlinks(gdev);
        device_unregister(dev);
        __ccwgroup_remove_cdev_refs(gdev);
    }
    mutex_unlock(&gdev->reg_mutex);
}

static ssize_t ccwgroup_ungroup_store(struct device *dev,
                      struct device_attribute *attr,
                      const char *buf, size_t count)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    int rc;

    /* Prevent concurrent online/offline processing and ungrouping. */
    if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
        return -EAGAIN;
    if (gdev->state != CCWGROUP_OFFLINE) {
        rc = -EINVAL;
        goto out;
    }
    /* Note that we cannot unregister the device from one of its
     * attribute methods, so we have to use this roundabout approach.
     */
    rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
out:
    if (rc) {
        if (rc != -EAGAIN)
            /* Release onoff "lock" when ungrouping failed. */
            atomic_set(&gdev->onoff, 0);
        return rc;
    }
    return count;
}
static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);

static struct attribute *ccwgroup_attrs[] = {
    &dev_attr_online.attr,
    &dev_attr_ungroup.attr,
    NULL,
};
static struct attribute_group ccwgroup_attr_group = {
    .attrs = ccwgroup_attrs,
};
static const struct attribute_group *ccwgroup_attr_groups[] = {
    &ccwgroup_attr_group,
    NULL,
};

static void ccwgroup_release(struct device *dev)
{
    kfree(to_ccwgroupdev(dev));
}

static int __ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
{
    char str[8];
    int i, rc;

    for (i = 0; i < gdev->count; i++) {
        rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj,
                       &gdev->dev.kobj, "group_device");
        if (rc) {
            for (--i; i >= 0; i--)
                sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
                          "group_device");
            return rc;
        }
    }
    for (i = 0; i < gdev->count; i++) {
        sprintf(str, "cdev%d", i);
        rc = sysfs_create_link(&gdev->dev.kobj,
                       &gdev->cdev[i]->dev.kobj, str);
        if (rc) {
            for (--i; i >= 0; i--) {
                sprintf(str, "cdev%d", i);
                sysfs_remove_link(&gdev->dev.kobj, str);
            }
            for (i = 0; i < gdev->count; i++)
                sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
                          "group_device");
            return rc;
        }
    }
    return 0;
}

static int __get_next_id(const char **buf, struct ccw_dev_id *id)
{
    unsigned int cssid, ssid, devno;
    int ret = 0, len;
    char *start, *end;

    start = (char *)*buf;
    end = strchr(start, ',');
    if (!end) {
        /* Last entry. Strip trailing newline, if applicable. */
        end = strchr(start, '\n');
        if (end)
            *end = '\0';
        len = strlen(start) + 1;
    } else {
        len = end - start + 1;
        end++;
    }
    if (len <= CCW_BUS_ID_SIZE) {
        if (sscanf(start, "%2x.%1x.%04x", &cssid, &ssid, &devno) != 3)
            ret = -EINVAL;
    } else
        ret = -EINVAL;

    if (!ret) {
        id->ssid = ssid;
        id->devno = devno;
    }
    *buf = end;
    return ret;
}

int ccwgroup_create_dev(struct device *parent, struct ccwgroup_driver *gdrv,
            int num_devices, const char *buf)
{
    struct ccwgroup_device *gdev;
    struct ccw_dev_id dev_id;
    int rc, i;

    gdev = kzalloc(sizeof(*gdev) + num_devices * sizeof(gdev->cdev[0]),
               GFP_KERNEL);
    if (!gdev)
        return -ENOMEM;

    atomic_set(&gdev->onoff, 0);
    mutex_init(&gdev->reg_mutex);
    mutex_lock(&gdev->reg_mutex);
    gdev->count = num_devices;
    gdev->dev.bus = &ccwgroup_bus_type;
    gdev->dev.parent = parent;
    gdev->dev.release = ccwgroup_release;
    device_initialize(&gdev->dev);

    for (i = 0; i < num_devices && buf; i++) {
        rc = __get_next_id(&buf, &dev_id);
        if (rc != 0)
            goto error;
        gdev->cdev[i] = get_ccwdev_by_dev_id(&dev_id);
        /*
         * All devices have to be of the same type in
         * order to be grouped.
         */
        if (!gdev->cdev[i] || !gdev->cdev[i]->drv ||
            gdev->cdev[i]->drv != gdev->cdev[0]->drv ||
            gdev->cdev[i]->id.driver_info !=
            gdev->cdev[0]->id.driver_info) {
            rc = -EINVAL;
            goto error;
        }
        /* Don't allow a device to belong to more than one group. */
        spin_lock_irq(gdev->cdev[i]->ccwlock);
        if (dev_get_drvdata(&gdev->cdev[i]->dev)) {
            spin_unlock_irq(gdev->cdev[i]->ccwlock);
            rc = -EINVAL;
            goto error;
        }
        dev_set_drvdata(&gdev->cdev[i]->dev, gdev);
        spin_unlock_irq(gdev->cdev[i]->ccwlock);
    }
    /* Check for sufficient number of bus ids. */
    if (i < num_devices) {
        rc = -EINVAL;
        goto error;
    }
    /* Check for trailing stuff. */
    if (i == num_devices && strlen(buf) > 0) {
        rc = -EINVAL;
        goto error;
    }

    dev_set_name(&gdev->dev, "%s", dev_name(&gdev->cdev[0]->dev));
    gdev->dev.groups = ccwgroup_attr_groups;

    if (gdrv) {
        gdev->dev.driver = &gdrv->driver;
        rc = gdrv->setup ? gdrv->setup(gdev) : 0;
        if (rc)
            goto error;
    }
    rc = device_add(&gdev->dev);
    if (rc)
        goto error;
    rc = __ccwgroup_create_symlinks(gdev);
    if (rc) {
        device_del(&gdev->dev);
        goto error;
    }
    mutex_unlock(&gdev->reg_mutex);
    return 0;
error:
    for (i = 0; i < num_devices; i++)
        if (gdev->cdev[i]) {
            spin_lock_irq(gdev->cdev[i]->ccwlock);
            if (dev_get_drvdata(&gdev->cdev[i]->dev) == gdev)
                dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
            spin_unlock_irq(gdev->cdev[i]->ccwlock);
            put_device(&gdev->cdev[i]->dev);
            gdev->cdev[i] = NULL;
        }
    mutex_unlock(&gdev->reg_mutex);
    put_device(&gdev->dev);
    return rc;
}
EXPORT_SYMBOL(ccwgroup_create_dev);

static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
                 void *data)
{
    struct device *dev = data;

    if (action == BUS_NOTIFY_UNBIND_DRIVER)
        device_schedule_callback(dev, ccwgroup_ungroup_callback);

    return NOTIFY_OK;
}

static struct notifier_block ccwgroup_nb = {
    .notifier_call = ccwgroup_notifier
};

static int __init init_ccwgroup(void)
{
    int ret;

    ret = bus_register(&ccwgroup_bus_type);
    if (ret)
        return ret;

    ret = bus_register_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
    if (ret)
        bus_unregister(&ccwgroup_bus_type);

    return ret;
}

static void __exit cleanup_ccwgroup(void)
{
    bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
    bus_unregister(&ccwgroup_bus_type);
}

module_init(init_ccwgroup);
module_exit(cleanup_ccwgroup);

/************************** driver stuff ******************************/

static int ccwgroup_remove(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);

    if (!dev->driver)
        return 0;
    if (gdrv->remove)
        gdrv->remove(gdev);

    return 0;
}

static void ccwgroup_shutdown(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);

    if (!dev->driver)
        return;
    if (gdrv->shutdown)
        gdrv->shutdown(gdev);
}

static int ccwgroup_pm_prepare(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);

    /* Fail while device is being set online/offline. */
    if (atomic_read(&gdev->onoff))
        return -EAGAIN;

    if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
        return 0;

    return gdrv->prepare ? gdrv->prepare(gdev) : 0;
}

static void ccwgroup_pm_complete(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);

    if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
        return;

    if (gdrv->complete)
        gdrv->complete(gdev);
}

static int ccwgroup_pm_freeze(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);

    if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
        return 0;

    return gdrv->freeze ? gdrv->freeze(gdev) : 0;
}

static int ccwgroup_pm_thaw(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);

    if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
        return 0;

    return gdrv->thaw ? gdrv->thaw(gdev) : 0;
}

static int ccwgroup_pm_restore(struct device *dev)
{
    struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
    struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);

    if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
        return 0;

    return gdrv->restore ? gdrv->restore(gdev) : 0;
}

static const struct dev_pm_ops ccwgroup_pm_ops = {
    .prepare = ccwgroup_pm_prepare,
    .complete = ccwgroup_pm_complete,
    .freeze = ccwgroup_pm_freeze,
    .thaw = ccwgroup_pm_thaw,
    .restore = ccwgroup_pm_restore,
};

static struct bus_type ccwgroup_bus_type = {
    .name   = "ccwgroup",
    .remove = ccwgroup_remove,
    .shutdown = ccwgroup_shutdown,
    .pm = &ccwgroup_pm_ops,
};

int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
{
    /* register our new driver with the core */
    cdriver->driver.bus = &ccwgroup_bus_type;

    return driver_register(&cdriver->driver);
}
EXPORT_SYMBOL(ccwgroup_driver_register);

static int __ccwgroup_match_all(struct device *dev, void *data)
{
    return 1;
}

void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
{
    struct device *dev;

    /* We don't want ccwgroup devices to live longer than their driver. */
    while ((dev = driver_find_device(&cdriver->driver, NULL, NULL,
                     __ccwgroup_match_all))) {
        struct ccwgroup_device *gdev = to_ccwgroupdev(dev);

        mutex_lock(&gdev->reg_mutex);
        __ccwgroup_remove_symlinks(gdev);
        device_unregister(dev);
        __ccwgroup_remove_cdev_refs(gdev);
        mutex_unlock(&gdev->reg_mutex);
        put_device(dev);
    }
    driver_unregister(&cdriver->driver);
}
EXPORT_SYMBOL(ccwgroup_driver_unregister);

int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
{
    return 0;
}
EXPORT_SYMBOL(ccwgroup_probe_ccwdev);

void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
{
    struct ccwgroup_device *gdev;

    /* Ignore offlining errors, device is gone anyway. */
    ccw_device_set_offline(cdev);
    /* If one of its devices is gone, the whole group is done for. */
    spin_lock_irq(cdev->ccwlock);
    gdev = dev_get_drvdata(&cdev->dev);
    if (!gdev) {
        spin_unlock_irq(cdev->ccwlock);
        return;
    }
    /* Get ccwgroup device reference for local processing. */
    get_device(&gdev->dev);
    spin_unlock_irq(cdev->ccwlock);
    /* Unregister group device. */
    mutex_lock(&gdev->reg_mutex);
    if (device_is_registered(&gdev->dev)) {
        __ccwgroup_remove_symlinks(gdev);
        device_unregister(&gdev->dev);
        __ccwgroup_remove_cdev_refs(gdev);
    }
    mutex_unlock(&gdev->reg_mutex);
    /* Release ccwgroup device reference for local processing. */
    put_device(&gdev->dev);
}
EXPORT_SYMBOL(ccwgroup_remove_ccwdev);
MODULE_LICENSE("GPL");