Add /sys/class/leds/<led>/link_device sysfs attribute
If this is the first LED associated with the device, create the
/sys/block/<disk>/blkdev_leds directory. Otherwise, increment its
reference count.
Create symlinks in /sys/class/leds/<led>/block_devices and
/sys/block/<disk>/blkdev_leds
If this the first device associated with *any* LED, schedule delayed work
to periodically check associated devices and blink LEDs
Signed-off-by: Ian Pilcher <arequipeno@xxxxxxxxx>
---
drivers/leds/trigger/ledtrig-blkdev.c | 160 ++++++++++++++++++++++++++
1 file changed, 160 insertions(+)
diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
index 6f78a9515976..26509837f037 100644
--- a/drivers/leds/trigger/ledtrig-blkdev.c
+++ b/drivers/leds/trigger/ledtrig-blkdev.c
@@ -71,6 +71,9 @@ static unsigned int ledtrig_blkdev_interval;
static void blkdev_process(struct work_struct *const work);
static DECLARE_DELAYED_WORK(ledtrig_blkdev_work, blkdev_process);
+/* Total number of device-to-LED associations */
+static unsigned int ledtrig_blkdev_count;
+
/*
*
@@ -220,6 +223,162 @@ static int blkdev_activate(struct led_classdev *const led_dev)
}
+/*
+ *
+ * link_device sysfs attribute - assocate a block device with this LED
+ *
+ */
+
+/* Gets or allocs & initializes the blkdev disk for a gendisk */
+static int blkdev_get_disk(struct gendisk *const gd)
+{
+ struct ledtrig_blkdev_disk *disk;
+ struct kobject *dir;
+
+ if (gd->ledtrig != NULL) {
+ kobject_get(gd->ledtrig->dir);
+ return 0;
+ }
+
+ disk = kmalloc(sizeof(*disk), GFP_KERNEL);
+ if (disk == NULL)
+ return -ENOMEM;
+
+ dir = kobject_create_and_add("linked_leds", &disk_to_dev(gd)->kobj);
+ if (dir == NULL) {
+ kfree(disk);
+ return -ENOMEM;
+ }
+
+ INIT_HLIST_HEAD(&disk->leds);
+ disk->gd = gd;
+ disk->dir = dir;
+ disk->read_ios = 0;
+ disk->write_ios = 0;
+
+ gd->ledtrig = disk;
+
+ return 0;
+}
+
+static void blkdev_put_disk(struct ledtrig_blkdev_disk *const disk)
+{
+ kobject_put(disk->dir);
+
+ if (hlist_empty(&disk->leds)) {
+ disk->gd->ledtrig = NULL;
+ kfree(disk);
+ }
+}
+
+static int blkdev_disk_link_locked(struct ledtrig_blkdev_led *const led,
+ struct gendisk *const gd)
+{
+ struct ledtrig_blkdev_link *link;
+ struct ledtrig_blkdev_disk *disk;
+ unsigned long delay;
+ int ret;
+
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (link == NULL) {
+ ret = -ENOMEM;
+ goto error_return;
+ }
+
+ ret = blkdev_get_disk(gd);
+ if (ret != 0)
+ goto error_free_link;
+
+ disk = gd->ledtrig;
+
+ ret = sysfs_create_link(disk->dir, &led->led_dev->dev->kobj,
+ led->led_dev->name);
+ if (ret != 0)
+ goto error_put_disk;
+
+ ret = sysfs_create_link(led->dir, &disk_to_dev(gd)->kobj,
+ gd->disk_name);
+ if (ret != 0)
+ goto error_remove_link;
+
+ link->disk = disk;
+ link->led = led;
+ hlist_add_head(&link->led_disks_node, &led->disks);
+ hlist_add_head(&link->disk_leds_node, &disk->leds);
+
+ if (ledtrig_blkdev_count == 0) {
+ delay = READ_ONCE(ledtrig_blkdev_interval);
+ WARN_ON(!schedule_delayed_work(&ledtrig_blkdev_work, delay));
+ }
+
+ ++ledtrig_blkdev_count;
+
+ return 0;
+
+error_remove_link:
+ sysfs_remove_link(disk->dir, led->led_dev->name);
+error_put_disk:
+ blkdev_put_disk(disk);
+error_free_link:
+ kfree(link);
+error_return:
+ return ret;
+}
+
+static bool blkdev_already_linked(const struct ledtrig_blkdev_led *const led,
+ const struct gendisk *const gd)
+{
+ const struct ledtrig_blkdev_link *link;
+
+ if (gd->ledtrig == NULL)
+ return false;
+
+ hlist_for_each_entry(link, &gd->ledtrig->leds, disk_leds_node) {
+
+ if (link->led == led)
+ return true;
+ }
+
+ return false;
+}
+
+static ssize_t link_device_store(struct device *const dev,
+ struct device_attribute *const attr,
+ const char *const buf, const size_t count)
+{
+ struct ledtrig_blkdev_led *const led = led_trigger_get_drvdata(dev);
+ struct gendisk *gd;
+ int ret;
+
+ ret = mutex_lock_interruptible(&ledtrig_blkdev_mutex);
+ if (ret != 0)
+ goto exit_return;
+
+ gd = ledtrig_blkdev_get_disk(buf);
+ if (gd == NULL) {
+ ret = -ENODEV;
+ goto exit_unlock;
+ }
+
+ if (blkdev_already_linked(led, gd)) {
+ ret = -EEXIST;
+ goto exit_put_disk;
+ }
+
+ ret = blkdev_disk_link_locked(led, gd);
+
+exit_put_disk:
+ if (ret != 0)
+ put_disk(gd);
+exit_unlock:
+ mutex_unlock(&ledtrig_blkdev_mutex);
+exit_return:
+ return (ret == 0) ? count : ret;
+}
+
+static DEVICE_ATTR_WO(link_device);
+
+
/*
*
* Initialization - register the trigger
@@ -227,6 +386,7 @@ static int blkdev_activate(struct led_classdev *const led_dev)
*/
static struct attribute *ledtrig_blkdev_attrs[] = {
+ &dev_attr_link_device.attr,
NULL
};
--
2.31.1
