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]> --- diff -uprN linux-2.6.22.orig/Documentation/leds-class.txt linux-2.6.22/Documentation/leds-class.txt --- linux-2.6.22.orig/Documentation/leds-class.txt 2007-07-09 01:32:17.000000000 +0200 +++ linux-2.6.22/Documentation/leds-class.txt 2007-07-17 17:07:44.000000000 +0200 @@ -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 +0 if the blink setting is supported, or -EINVAL 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 ================== diff -uprN linux-2.6.22.orig/drivers/leds/ledtrig-timer.c linux-2.6.22/drivers/leds/ledtrig-timer.c --- linux-2.6.22.orig/drivers/leds/ledtrig-timer.c 2007-07-09 01:32:17.000000000 +0200 +++ linux-2.6.22/drivers/leds/ledtrig-timer.c 2007-07-17 17:45:56.000000000 +0200 @@ -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; } diff -uprN linux-2.6.22.orig/include/linux/leds.h linux-2.6.22/include/linux/leds.h --- linux-2.6.22.orig/include/linux/leds.h 2007-07-09 01:32:17.000000000 +0200 +++ linux-2.6.22/include/linux/leds.h 2007-07-17 10:52:18.000000000 +0200 @@ -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 */