[PATCH] LEDS-One-Shot-Timer-Trigger-implementation

[Shuah Khan]

Signed-off-by: Shuah Khan <shuahkhan@xxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxx>
Cc: Richard Purdie <rpurdie@xxxxxxxxxxxxxxx>
---
 Documentation/leds/leds-one-shot-timer.txt |   79 +++++++++++++++++++++
 drivers/leds/led-class.c                   |    4 +-
 drivers/leds/led-core.c                    |   26 ++++++-
 drivers/leds/leds.h                        |    2 +
 drivers/leds/ledtrig-timer.c               |  104 ++++++++++++++++++++--------
 5 files changed, 180 insertions(+), 35 deletions(-)
 create mode 100644 Documentation/leds/leds-one-shot-timer.txt

diff --git a/Documentation/leds/leds-one-shot-timer.txt b/Documentation/leds/leds-one-shot-timer.txt
new file mode 100644
index 0000000..a5429dd
--- /dev/null
+++ b/Documentation/leds/leds-one-shot-timer.txt
@@ -0,0 +1,79 @@
+
+LED one shot timer feature
+===========================
+
+LED infrastructure lacks support for one shot timer trigger and activation.
+The current support allows for setting two timers, one for specifying how
+long a state to be on, and the second for how long the state to be off. For
+example, delay_on value specifies the time period an LED should stay in on
+state, followed by a delay_off value that specifies how long the LED should
+stay in off state. The on and off cycle repeats until the trigger gets
+deactivated. There is no provision for one time activation to implement
+features that require an on or off state to be held just once and then stay
+in the original state forever.
+
+This feature will help implement vibrate functionality which requires one
+time activation of vibrate mode without a continuous vibrate on/off cycles.
+
+This patch implements the timer-no-default trigger support by enhancing the
+current led-class, led-core, and ledtrig-timer drivers to:
+
+- Add support for forever timer case. forever tag can be written to delay_on
+  or delay_off files. Internally forever is mapped to ULONG_MAX with no timer
+  associated with it.
+
+- The led_blink_set() which takes two pointers to times one each for delay_on
+  and delay_off has been extended so that a NULL instead of a pointer means
+  "forever".
+
+- Add a new timer-no-default trigger to ledtrig-timer
+
+The above enhancements support the following use-cases:
+
+use-case 1:
+echo timer-no-default > /sys/class/leds/SOMELED/trigger
+echo forever > /sys/class/leds/SOMELED/delay_off
+echo 2000 > /sys/class/leds/SOMELED/delay_on
+
+When timer-no-default is activated in step1, unlike the timer trigger case,
+timer-no-default activate routine activates the trigger without starting
+any timers. The default 1 HZ delay_on and delay_off timers won't be started
+like in the case of timer trigger activation. Not starting timers ensures
+that the one time state isn't stuck if some error occurs before actual timer
+periods are specified. delay_on and delay_off files get created with 0
+values. Please note that it is important to set delay_off to forever prior
+to setting delay_on value. If the order is reversed, the LED will be turned
+on, with no timer set to turn it off.
+
+When delay_off value is specified in step 2, delay_off_store recognizes the
+special forever tag and records it and returns without starting any timer.
+Internally forever maps to ULONG_MAX. The led_blink_set() which takes
+two pointers to times one each for delay_on and delay_off has been extended
+so that a NULL instead of a pointer means "forever".
+
+When delay_on value is specified in step 3, a timer gets started for
+delay_on period, and delay_off stays at ULONG_MAX with no timer associated
+with it.
+
+use-case 2:
+echo timer-no-default > /sys/class/leds/SOMELED/trigger
+echo forever > /sys/class/leds/SOMELED/delay_on
+echo 2000 > /sys/class/leds/SOMELED/delay_off
+
+When timer-no-default is activated in step1, unlike the timer trigger case,
+timer-no-default activate routine activates the trigger without starting
+any timers. The default 1 HZ delay_on and delay_off timers won't be started
+like in the case of timer trigger activation. Not starting timers ensures
+that the one time state isn't stuck if some error occurs before actual timer
+periods are specified. delay_on and delay_off files get created with 0
+values. Please note that it is important to set delay_on to forever prior
+to setting delay_off value. If the order is reversed, the LED will be turned
+off, with no timer set to turn it back on.
+
+When delay_on value is specified in step 2, delay_on_store recognizes the
+special forever tag and records it and returns without starting any timer.
+Internally forever maps to ULONG_MAX.
+
+When delay_off value is specified in step 3, a timer gets started for
+delay_off period, and delay_on stays at ULONG_MAX with no timer associated
+with it.
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 5bff843..ed123ba 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -107,7 +107,9 @@ static void led_timer_function(unsigned long data)
 
 	led_set_brightness(led_cdev, brightness);
 
-	mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
+	if (delay != LED_TIMER_FOREVER)
+		mod_timer(&led_cdev->blink_timer,
+			jiffies + msecs_to_jiffies(delay));
 }
 
 /**
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index d686004..419b0bc 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -72,17 +72,35 @@ void led_blink_set(struct led_classdev *led_cdev,
 		   unsigned long *delay_on,
 		   unsigned long *delay_off)
 {
+	unsigned long val_on;
+	unsigned long val_off;
+
 	del_timer_sync(&led_cdev->blink_timer);
 
-	if (led_cdev->blink_set &&
+	if (delay_on && delay_off && led_cdev->blink_set &&
 	    !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 		return;
 
+	/* if delay_on is null, leave it on forever after delay_off period
+	   if delay_off is null, leave it off forever after delay on period */
+	if (!delay_on)
+		val_on = LED_TIMER_FOREVER;
+	else
+		val_on = *delay_on;
+
+	if (!delay_off)
+		val_off = LED_TIMER_FOREVER;
+	else
+		val_off = *delay_off;
+
 	/* blink with 1 Hz as default if nothing specified */
-	if (!*delay_on && !*delay_off)
-		*delay_on = *delay_off = 500;
+	if (!val_on && !val_off) {
+		val_on = val_off = 500;
+		*delay_on = 500;
+		*delay_off = 500;
+	}
 
-	led_set_software_blink(led_cdev, *delay_on, *delay_off);
+	led_set_software_blink(led_cdev, val_on, val_off);
 }
 EXPORT_SYMBOL(led_blink_set);
 
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index e77c7f8..b2cda9f 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -17,6 +17,8 @@
 #include <linux/rwsem.h>
 #include <linux/leds.h>
 
+#define LED_TIMER_FOREVER ULONG_MAX
+
 static inline void led_set_brightness(struct led_classdev *led_cdev,
 					enum led_brightness value)
 {
diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c
index 328c64c..e323cf2 100644
--- a/drivers/leds/ledtrig-timer.c
+++ b/drivers/leds/ledtrig-timer.c
@@ -24,6 +24,9 @@ static ssize_t led_delay_on_show(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 
+	if (led_cdev->blink_delay_on == LED_TIMER_FOREVER)
+		return sprintf(buf, "forever\n");
+
 	return sprintf(buf, "%lu\n", led_cdev->blink_delay_on);
 }
 
@@ -32,17 +35,25 @@ static ssize_t led_delay_on_store(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	int ret = -EINVAL;
-	char *after;
-	unsigned long state = simple_strtoul(buf, &after, 10);
-	size_t count = after - buf;
-
-	if (isspace(*after))
-		count++;
 
-	if (count == size) {
-		led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
-		led_cdev->blink_delay_on = state;
-		ret = count;
+	if (strncmp(buf, "forever", 7) == 0) {
+		led_blink_set(led_cdev, NULL, &led_cdev->blink_delay_off);
+		led_cdev->blink_delay_on = LED_TIMER_FOREVER;
+		ret = size;
+	} else {
+		char *after;
+		unsigned long state = simple_strtoul(buf, &after, 10);
+		size_t count = after - buf;
+
+		if (isspace(*after))
+			count++;
+
+		if (count == size) {
+			led_blink_set(led_cdev, &state,
+				&led_cdev->blink_delay_off);
+			led_cdev->blink_delay_on = state;
+			ret = count;
+		}
 	}
 
 	return ret;
@@ -53,6 +64,9 @@ static ssize_t led_delay_off_show(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 
+	if (led_cdev->blink_delay_off == LED_TIMER_FOREVER)
+		return sprintf(buf, "forever\n");
+
 	return sprintf(buf, "%lu\n", led_cdev->blink_delay_off);
 }
 
@@ -61,17 +75,24 @@ static ssize_t led_delay_off_store(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	int ret = -EINVAL;
-	char *after;
-	unsigned long state = simple_strtoul(buf, &after, 10);
-	size_t count = after - buf;
 
-	if (isspace(*after))
-		count++;
-
-	if (count == size) {
-		led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
-		led_cdev->blink_delay_off = state;
-		ret = count;
+	if (strncmp(buf, "forever", 7) == 0) {
+		led_blink_set(led_cdev, &led_cdev->blink_delay_on, NULL);
+		led_cdev->blink_delay_off = LED_TIMER_FOREVER;
+	} else {
+		char *after;
+		unsigned long state = simple_strtoul(buf, &after, 10);
+		size_t count = after - buf;
+
+		if (isspace(*after))
+			count++;
+
+		if (count == size) {
+			led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+				&state);
+			led_cdev->blink_delay_off = state;
+			ret = count;
+		}
 	}
 
 	return ret;
@@ -80,7 +101,7 @@ static ssize_t led_delay_off_store(struct device *dev,
 static DEVICE_ATTR(delay_on, 0644, led_delay_on_show, led_delay_on_store);
 static DEVICE_ATTR(delay_off, 0644, led_delay_off_show, led_delay_off_store);
 
-static void timer_trig_activate(struct led_classdev *led_cdev)
+static void timer_trig_activate_common(struct led_classdev *led_cdev)
 {
 	int rc;
 
@@ -91,17 +112,24 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
 		return;
 	rc = device_create_file(led_cdev->dev, &dev_attr_delay_off);
 	if (rc)
-		goto err_out_delayon;
-
-	led_blink_set(led_cdev, &led_cdev->blink_delay_on,
-		      &led_cdev->blink_delay_off);
+		device_remove_file(led_cdev->dev, &dev_attr_delay_on);
 
-	led_cdev->trigger_data = (void *)1;
+	else
+		led_cdev->trigger_data = (void *)1;
+}
 
-	return;
+static void timer_trig_activate_timer_no_default(struct led_classdev *led_cdev)
+{
+	timer_trig_activate_common(led_cdev);
+}
 
-err_out_delayon:
-	device_remove_file(led_cdev->dev, &dev_attr_delay_on);
+static void timer_trig_activate(struct led_classdev *led_cdev)
+{
+	timer_trig_activate_common(led_cdev);
+	if (led_cdev->trigger_data) {
+		led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+		      &led_cdev->blink_delay_off);
+	}
 }
 
 static void timer_trig_deactivate(struct led_classdev *led_cdev)
@@ -121,14 +149,30 @@ static struct led_trigger timer_led_trigger = {
 	.deactivate = timer_trig_deactivate,
 };
 
+static struct led_trigger timer_no_default_led_trigger = {
+	.name     = "timer-no-default",
+	.activate = timer_trig_activate_timer_no_default,
+	.deactivate = timer_trig_deactivate,
+};
+
 static int __init timer_trig_init(void)
 {
-	return led_trigger_register(&timer_led_trigger);
+	int rc = 0;
+
+	rc = led_trigger_register(&timer_led_trigger);
+	if (!rc) {
+		rc = led_trigger_register(&timer_no_default_led_trigger);
+		if (rc)
+			led_trigger_unregister(&timer_led_trigger);
+	}
+
+	return rc;
 }
 
 static void __exit timer_trig_exit(void)
 {
 	led_trigger_unregister(&timer_led_trigger);
+	led_trigger_unregister(&timer_no_default_led_trigger);
 }
 
 module_init(timer_trig_init);
-- 
1.7.5.4





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