mmc: add led trigger

Add a led trigger for each host controller that indicates if there
is a request active on the controller.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 37b7618..64fbc97 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -15,6 +15,7 @@
 #include <linux/err.h>
 #include <linux/idr.h>
 #include <linux/pagemap.h>
+#include <linux/leds.h>
 
 #include <linux/mmc/host.h>
 
@@ -115,6 +116,8 @@
 	snprintf(host->class_dev.bus_id, BUS_ID_SIZE,
 		 "mmc%d", host->index);
 
+	led_trigger_register_simple(host->class_dev.bus_id, &host->led);
+
 	err = device_add(&host->class_dev);
 	if (err)
 		return err;
@@ -140,6 +143,8 @@
 
 	device_del(&host->class_dev);
 
+	led_trigger_unregister(host->led);
+
 	spin_lock(&mmc_host_lock);
 	idr_remove(&mmc_host_idr, host->index);
 	spin_unlock(&mmc_host_lock);