leds-clevo-mail: hw accelerated LED blink extension

PATCH In review Németh Márton 2 participants 3 messages Jul 17, 2007

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Németh Márton

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2007-07-17 10:18 UTC #0 lore raw

PATCH 2/3 leds-clevo-mail: hw accelerated LED blink extension

From: Márton Németh <[email protected]>

Extends the leds subsystem with a blink_set() callback function which can optionally implemented by a LED driver. If implemented, the driver can use the hardware acceleration for blinking a LED.

Signed-off-by Márton Németh <[email protected]>

---

Documentation/leds-class.txt +11 -4

diff -uprN linux-2.6.22.orig/Documentation/leds-class.txt linux-2.6.22/Documentation/leds-class.txt
@@ -47,6 +47,17 @@ overhead, I suggest these become part of
 above leaves scope for further attributes should they be needed.
 
 
+Hardware accelerated blink of LEDs
+==================================
+
+Some LEDs can be programmed to blink without any CPU interaction. To
+support this feature, a LED driver can optionally implement the
+blink_set() function (see <linux/leds.h>). If implemeted, the
+ledtrig-timer tries to use it. The blink_set() function should return
+1 if the blink setting is supported, or 0 otherwise, which means that
+the LED will be turned on and off from software.
+
+
 Known Issues
 ============

@@ -55,10 +66,6 @@ would cause nightmare dependency issues.
 compared to the benefits the simple trigger functionality brings. The
 rest of the LED subsystem can be modular.
 
-Some leds can be programmed to flash in hardware. As this isn't a generic
-LED device property, this should be exported as a device specific sysfs
-attribute rather than part of the class if this functionality is required.
-
 
 Future Development
 ==================

drivers/leds/ledtrig-timer.c +30 -4

diff -uprN linux-2.6.22.orig/drivers/leds/ledtrig-timer.c linux-2.6.22/drivers/leds/ledtrig-timer.c
@@ -76,8 +76,21 @@ static ssize_t led_delay_on_store(struct
 		count++;
 
 	if (count == size) {
-		timer_data->delay_on = state;
-		mod_timer(&timer_data->timer, jiffies + 1);
+		if (timer_data->delay_on != state) {
+			/* the new value differs from the previous */
+			timer_data->delay_on = state;
+
+			/* deactivate previous settings */
+			del_timer_sync(&timer_data->timer);
+
+			/* try to activate hardware acceleration, if any */
+			if (!led_cdev->blink_set ||
+			    !led_cdev->blink_set(led_cdev,
+				timer_data->delay_on, timer_data->delay_off)) {
+				/* no hardware acceleration, blink via timer */
+				mod_timer(&timer_data->timer, jiffies + 1);
+			}
+		}
 		ret = count;
 	}

@@ -108,8 +121,21 @@ static ssize_t led_delay_off_store(struc
 		count++;
 
 	if (count == size) {
-		timer_data->delay_off = state;
-		mod_timer(&timer_data->timer, jiffies + 1);
+		if (timer_data->delay_off != state) {
+			/* the new value differs from the previous */
+			timer_data->delay_off = state;
+
+			/* deactivate previous settings */
+			del_timer_sync(&timer_data->timer);
+
+			/* try to activate hardware acceleration, if any */
+			if (!led_cdev->blink_set ||
+			    !led_cdev->blink_set(led_cdev,
+				timer_data->delay_on, timer_data->delay_off)) {
+				/* no hardware acceleration, blink via timer */
+				mod_timer(&timer_data->timer, jiffies + 1);
+			}
+		}
 		ret = count;
 	}

include/linux/leds.h +5 -0

diff -uprN linux-2.6.22.orig/include/linux/leds.h linux-2.6.22/include/linux/leds.h
@@ -38,6 +38,11 @@ struct led_classdev {
 	void		(*brightness_set)(struct led_classdev *led_cdev,
 					  enum led_brightness brightness);
 
+	/* Activate hardware accelerated blink */
+	int		(*blink_set)(struct led_classdev *led_cdev,
+				     int delay_on, int delay_off);
+
+
 	struct class_device	*class_dev;
 	struct list_head	 node;			/* LED Device list */
 	char			*default_trigger;	/* Trigger to use */

Dmitry Torokhov

2007-07-17 13:04 UTC #1 lore raw

Documentation/leds-class.txt overhead, I suggest these become part of · line 58

Quoted 10 lines · Németh Márton

Documentation/leds-class.txt +9 -0

+Hardware accelerated blink of LEDs
+==================================
+
+Some LEDs can be programmed to blink without any CPU interaction. To
+support this feature, a LED driver can optionally implement the
+blink_set() function (see <linux/leds.h>). If implemeted, the
+ledtrig-timer tries to use it. The blink_set() function should return
+1 if the blink setting is supported, or 0 otherwise, which means that
+the LED will be turned on and off from software.

Normally object methods in kernel return 0 on success and error code (such as -EINVAL for unsupported parameters) on error.

Signature · 1 line

Dmitry