leds: Extends disk trigger for reads and writes

This adds two new disk triggers for triggering on reads
and writes respectively, named "disk-read" and "disk-write".

The use case comes from working on the D-Link DNS-313 NAS
box. This features an RGB LED for disk activity. with
these two triggers I can couple the green LED to read
activity and the red LED to write activity, which gives
the appropriate user feedback about what is happening
on the disk. When tested it gave exactly the feedback
desired.

The in-kernel interface is simply changed to pass a bool
indicating if the activity is write activity and update
each trigger (and the composite "disk-activity" trigger)
depending on what is passed in.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

drivers/ata/libata-core.c

@@ -5219,7 +5219,7 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
 	struct ata_port *ap = qc->ap;
 
 	/* Trigger the LED (if available) */
-	ledtrig_disk_activity();
+	ledtrig_disk_activity(!!(qc->tf.flags & ATA_TFLAG_WRITE));
 
 	/* XXX: New EH and old EH use different mechanisms to
 	 * synchronize EH with regular execution path.

drivers/ide/ide-disk.c

@@ -187,7 +187,7 @@ static ide_startstop_t ide_do_rw_disk(ide_drive_t *drive, struct request *rq,
 	BUG_ON(drive->dev_flags & IDE_DFLAG_BLOCKED);
 	BUG_ON(blk_rq_is_passthrough(rq));
 
-	ledtrig_disk_activity();
+	ledtrig_disk_activity(rq_data_dir(rq) == WRITE);
 
 	pr_debug("%s: %sing: block=%llu, sectors=%u\n",
 		 drive->name, rq_data_dir(rq) == READ ? "read" : "writ",

drivers/leds/trigger/ledtrig-disk.c

@@ -18,9 +18,11 @@
 #define BLINK_DELAY 30
 
 DEFINE_LED_TRIGGER(ledtrig_disk);
+DEFINE_LED_TRIGGER(ledtrig_disk_read);
+DEFINE_LED_TRIGGER(ledtrig_disk_write);
 DEFINE_LED_TRIGGER(ledtrig_ide);
 
-void ledtrig_disk_activity(void)
+void ledtrig_disk_activity(bool write)
 {
 	unsigned long blink_delay = BLINK_DELAY;
 
@@ -28,12 +30,20 @@ void ledtrig_disk_activity(void)
 				  &blink_delay, &blink_delay, 0);
 	led_trigger_blink_oneshot(ledtrig_ide,
 				  &blink_delay, &blink_delay, 0);
+	if (write)
+		led_trigger_blink_oneshot(ledtrig_disk_write,
+					  &blink_delay, &blink_delay, 0);
+	else
+		led_trigger_blink_oneshot(ledtrig_disk_read,
+					  &blink_delay, &blink_delay, 0);
 }
 EXPORT_SYMBOL(ledtrig_disk_activity);
 
 static int __init ledtrig_disk_init(void)
 {
 	led_trigger_register_simple("disk-activity", &ledtrig_disk);
+	led_trigger_register_simple("disk-read", &ledtrig_disk_read);
+	led_trigger_register_simple("disk-write", &ledtrig_disk_write);
 	led_trigger_register_simple("ide-disk", &ledtrig_ide);
 
 	return 0;

include/linux/leds.h

@@ -346,9 +346,9 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
 
 /* Trigger specific functions */
 #ifdef CONFIG_LEDS_TRIGGER_DISK
-extern void ledtrig_disk_activity(void);
+extern void ledtrig_disk_activity(bool write);
 #else
-static inline void ledtrig_disk_activity(void) {}
+static inline void ledtrig_disk_activity(bool write) {}
 #endif
 
 #ifdef CONFIG_LEDS_TRIGGER_MTD