dasd_devmap.c

linux-2.6.15.6

	spin_lock(&dasd_devmap_lock);
	devmap = ERR_PTR(-ENODEV);
	hash = dasd_hash_busid(bus_id);
	list_for_each_entry(tmp, &dasd_hashlists[hash], list) {
		if (strncmp(tmp->bus_id, bus_id, BUS_ID_SIZE) == 0) {
			devmap = tmp;
			break;
		}
	}
	spin_unlock(&dasd_devmap_lock);
	return devmap;
}

/*
 * Check if busid has been added to the list of dasd ranges.
 */
int
dasd_busid_known(char *bus_id)
{
	return IS_ERR(dasd_find_busid(bus_id)) ? -ENOENT : 0;
}

/*
 * Forget all about the device numbers added so far.
 * This may only be called at module unload or system shutdown.
 */
static void
dasd_forget_ranges(void)
{
	struct dasd_devmap *devmap, *n;
	int i;

	spin_lock(&dasd_devmap_lock);
	for (i = 0; i < 256; i++) {
		list_for_each_entry_safe(devmap, n, &dasd_hashlists[i], list) {
			if (devmap->device != NULL)
				BUG();
			list_del(&devmap->list);
			kfree(devmap);
		}
	}
	spin_unlock(&dasd_devmap_lock);
}

/*
 * Find the device struct by its device index.
 */
struct dasd_device *
dasd_device_from_devindex(int devindex)
{
	struct dasd_devmap *devmap, *tmp;
	struct dasd_device *device;
	int i;

	spin_lock(&dasd_devmap_lock);
	devmap = 0;
	for (i = 0; (i < 256) && !devmap; i++)
		list_for_each_entry(tmp, &dasd_hashlists[i], list)
			if (tmp->devindex == devindex) {
				/* Found the devmap for the device. */
				devmap = tmp;
				break;
			}
	if (devmap && devmap->device) {
		device = devmap->device;
		dasd_get_device(device);
	} else
		device = ERR_PTR(-ENODEV);
	spin_unlock(&dasd_devmap_lock);
	return device;
}

/*
 * Return devmap for cdev. If no devmap exists yet, create one and
 * connect it to the cdev.
 */
static struct dasd_devmap *
dasd_devmap_from_cdev(struct ccw_device *cdev)
{
	struct dasd_devmap *devmap;

	devmap = dasd_find_busid(cdev->dev.bus_id);
	if (IS_ERR(devmap))
		devmap = dasd_add_busid(cdev->dev.bus_id,
					DASD_FEATURE_DEFAULT);
	return devmap;
}

/*
 * Create a dasd device structure for cdev.
 */
struct dasd_device *
dasd_create_device(struct ccw_device *cdev)
{
	struct dasd_devmap *devmap;
	struct dasd_device *device;
	int rc;

	devmap = dasd_devmap_from_cdev(cdev);
	if (IS_ERR(devmap))
		return (void *) devmap;
	cdev->dev.driver_data = devmap;

	device = dasd_alloc_device();
	if (IS_ERR(device))
		return device;
	atomic_set(&device->ref_count, 2);

	spin_lock(&dasd_devmap_lock);
	if (!devmap->device) {
		devmap->device = device;
		device->devindex = devmap->devindex;
		device->features = devmap->features;
		get_device(&cdev->dev);
		device->cdev = cdev;
		rc = 0;
	} else
		/* Someone else was faster. */
		rc = -EBUSY;
	spin_unlock(&dasd_devmap_lock);

	if (rc) {
		dasd_free_device(device);
		return ERR_PTR(rc);
	}
	return device;
}

/*
 * Wait queue for dasd_delete_device waits.
 */
static DECLARE_WAIT_QUEUE_HEAD(dasd_delete_wq);

/*
 * Remove a dasd device structure. The passed referenced
 * is destroyed.
 */
void
dasd_delete_device(struct dasd_device *device)
{
	struct ccw_device *cdev;
	struct dasd_devmap *devmap;

	/* First remove device pointer from devmap. */
	devmap = dasd_find_busid(device->cdev->dev.bus_id);
	if (IS_ERR(devmap))
		BUG();
	spin_lock(&dasd_devmap_lock);
	if (devmap->device != device) {
		spin_unlock(&dasd_devmap_lock);
		dasd_put_device(device);
		return;
	}
	devmap->device = NULL;
	spin_unlock(&dasd_devmap_lock);

	/* Drop ref_count by 2, one for the devmap reference and
	 * one for the passed reference. */
	atomic_sub(2, &device->ref_count);

	/* Wait for reference counter to drop to zero. */
	wait_event(dasd_delete_wq, atomic_read(&device->ref_count) == 0);

	/* Disconnect dasd_device structure from ccw_device structure. */
	cdev = device->cdev;
	device->cdev = NULL;

	/* Disconnect dasd_devmap structure from ccw_device structure. */
	cdev->dev.driver_data = NULL;

	/* Put ccw_device structure. */
	put_device(&cdev->dev);

	/* Now the device structure can be freed. */
	dasd_free_device(device);
}

/*
 * Reference counter dropped to zero. Wake up waiter
 * in dasd_delete_device.
 */
void
dasd_put_device_wake(struct dasd_device *device)
{
	wake_up(&dasd_delete_wq);
}

/*
 * Return dasd_device structure associated with cdev.
 */
struct dasd_device *
dasd_device_from_cdev(struct ccw_device *cdev)
{
	struct dasd_devmap *devmap;
	struct dasd_device *device;

	device = ERR_PTR(-ENODEV);
	spin_lock(&dasd_devmap_lock);
	devmap = cdev->dev.driver_data;
	if (devmap && devmap->device) {
		device = devmap->device;
		dasd_get_device(device);
	}
	spin_unlock(&dasd_devmap_lock);
	return device;
}

/*
 * SECTION: files in sysfs
 */

/*
 * readonly controls the readonly status of a dasd
 */
static ssize_t
dasd_ro_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct dasd_devmap *devmap;
	int ro_flag;

	devmap = dasd_find_busid(dev->bus_id);
	if (!IS_ERR(devmap))
		ro_flag = (devmap->features & DASD_FEATURE_READONLY) != 0;
	else
		ro_flag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_READONLY) != 0;
	return snprintf(buf, PAGE_SIZE, ro_flag ? "1\n" : "0\n");
}

static ssize_t
dasd_ro_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
	struct dasd_devmap *devmap;
	int ro_flag;

	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
	if (IS_ERR(devmap))
		return PTR_ERR(devmap);
	ro_flag = buf[0] == '1';
	spin_lock(&dasd_devmap_lock);
	if (ro_flag)
		devmap->features |= DASD_FEATURE_READONLY;
	else
		devmap->features &= ~DASD_FEATURE_READONLY;
	if (devmap->device)
		devmap->device->features = devmap->features;
	if (devmap->device && devmap->device->gdp)
		set_disk_ro(devmap->device->gdp, ro_flag);
	spin_unlock(&dasd_devmap_lock);
	return count;
}

static DEVICE_ATTR(readonly, 0644, dasd_ro_show, dasd_ro_store);

/*
 * use_diag controls whether the driver should use diag rather than ssch
 * to talk to the device
 */
static ssize_t 
dasd_use_diag_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct dasd_devmap *devmap;
	int use_diag;

	devmap = dasd_find_busid(dev->bus_id);
	if (!IS_ERR(devmap))
		use_diag = (devmap->features & DASD_FEATURE_USEDIAG) != 0;
	else
		use_diag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_USEDIAG) != 0;
	return sprintf(buf, use_diag ? "1\n" : "0\n");
}

static ssize_t
dasd_use_diag_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
	struct dasd_devmap *devmap;
	ssize_t rc;
	int use_diag;

	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
	if (IS_ERR(devmap))
		return PTR_ERR(devmap);
	use_diag = buf[0] == '1';
	spin_lock(&dasd_devmap_lock);
	/* Changing diag discipline flag is only allowed in offline state. */
	rc = count;
	if (!devmap->device) {
		if (use_diag)
			devmap->features |= DASD_FEATURE_USEDIAG;
		else
			devmap->features &= ~DASD_FEATURE_USEDIAG;
	} else
		rc = -EPERM;
	spin_unlock(&dasd_devmap_lock);
	return rc;
}

static
DEVICE_ATTR(use_diag, 0644, dasd_use_diag_show, dasd_use_diag_store);

static ssize_t
dasd_discipline_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct dasd_devmap *devmap;
	char *dname;

	spin_lock(&dasd_devmap_lock);
	dname = "none";
	devmap = dev->driver_data;
	if (devmap && devmap->device && devmap->device->discipline)
		dname = devmap->device->discipline->name;
	spin_unlock(&dasd_devmap_lock);
	return snprintf(buf, PAGE_SIZE, "%s\n", dname);
}

static DEVICE_ATTR(discipline, 0444, dasd_discipline_show, NULL);

static struct attribute * dasd_attrs[] = {
	&dev_attr_readonly.attr,
	&dev_attr_discipline.attr,
	&dev_attr_use_diag.attr,
	NULL,
};

static struct attribute_group dasd_attr_group = {
	.attrs = dasd_attrs,
};

/*
 * Return value of the specified feature.
 */
int
dasd_get_feature(struct ccw_device *cdev, int feature)
{
	struct dasd_devmap *devmap;

	devmap = dasd_find_busid(cdev->dev.bus_id);
	if (IS_ERR(devmap))
		return (int) PTR_ERR(devmap);

	return ((devmap->features & feature) != 0);
}

/*
 * Set / reset given feature.
 * Flag indicates wether to set (!=0) or the reset (=0) the feature.
 */
int
dasd_set_feature(struct ccw_device *cdev, int feature, int flag)
{
	struct dasd_devmap *devmap;

	devmap = dasd_find_busid(cdev->dev.bus_id);
	if (IS_ERR(devmap))
		return (int) PTR_ERR(devmap);

	spin_lock(&dasd_devmap_lock);
	if (flag)
		devmap->features |= feature;
	else
		devmap->features &= ~feature;
	if (devmap->device)
		devmap->device->features = devmap->features;
	spin_unlock(&dasd_devmap_lock);
	return 0;
}


int
dasd_add_sysfs_files(struct ccw_device *cdev)
{
	return sysfs_create_group(&cdev->dev.kobj, &dasd_attr_group);
}

void
dasd_remove_sysfs_files(struct ccw_device *cdev)
{
	sysfs_remove_group(&cdev->dev.kobj, &dasd_attr_group);
}


int
dasd_devmap_init(void)
{
	int i;

	/* Initialize devmap structures. */
	dasd_max_devindex = 0;
	for (i = 0; i < 256; i++)
		INIT_LIST_HEAD(&dasd_hashlists[i]);
	return 0;

}

void
dasd_devmap_exit(void)
{
	dasd_forget_ranges();
}