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leds-clevo-mail: hw accelerated LED blink extension

PATCH New Németh Márton 1 participant 1 message Oct 28, 2007

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PATCH 3/4 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 be optionally implemented by a LED driver. If implemented, the driver can use the hardware acceleration for blinking a LED.

---

Documentation/leds-class.txt +21 -4
diff -uprN linux-2.6.24-rc1.b/Documentation/leds-class.txt linux-2.6.24-rc1.c/Documentation/leds-class.txt
@@ -49,6 +49,27 @@ 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
+0 if the blink setting is supported, or -EINVAL otherwise, which means
+that the LED will be turned on and off from software by the leds
+subsystem.
+
+The blink_set() function should choose a user friendly blinking
+value if it is called with *delay_on==0 && *delay_off==0 parameters. In
+this case the driver should give back the chosen value through delay_on
+and delay_off parameters to the leds subsystem.
+
+Any call to the brightness_set() callback function should cancel the
+previously programmed hardware blinking function so setting the brightness
+to 0 can also cancel the blinking of the LED.
+
+
 Known Issues
 ============
 
@@ -57,10 +78,6 @@ 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/Kconfig +5 -1
diff -uprN linux-2.6.24-rc1.b/drivers/leds/Kconfig linux-2.6.24-rc1.c/drivers/leds/Kconfig
@@ -152,7 +152,11 @@ config LEDS_TRIGGER_TIMER
 	depends on LEDS_TRIGGERS
 	help
 	  This allows LEDs to be controlled by a programmable timer
-	  via sysfs. If unsure, say Y.
+	  via sysfs. Some LED hardware can be programmed to start
+	  blinking the LED without any further software interaction.
+	  For more details read Documentation/leds-class.txt.
+
+	  If unsure, say Y.
 
 config LEDS_TRIGGER_IDE_DISK
 	bool "LED IDE Disk Trigger"
drivers/leds/ledtrig-timer.c +37 -4

59 lines not on this page · raw message

include/linux/leds.h +5 -0
diff -uprN linux-2.6.24-rc1.b/include/linux/leds.h linux-2.6.24-rc1.c/include/linux/leds.h
@@ -37,6 +37,11 @@ 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,
+				     unsigned long *delay_on,
+				     unsigned long *delay_off);
+
 	struct device		*dev;
 	struct list_head	 node;			/* LED Device list */
 	char			*default_trigger;	/* Trigger to use */