Date:	Sun, 01 Apr 2012 13:53:59 -0600
From:	Shuah Khan <shuahkhan@...il.com>
To:	akpm@...ux-foundation.org
Cc:	shuahkhan@...il.com, neilb@...e.de, rpurdie@...ux.intel.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH RESEND] LEDS-One-Shot-Timer-Trigger-implementation

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.

>From 1ebe0fd67580da833f8f06fc3119445e9991100f Mon Sep 17 00:00:00 2001
From: Shuah Khan <shuahkhan@...il.com>
Date: Sat, 31 Mar 2012 21:56:07 -0600
Subject: [PATCH] LEDS-One-Shot-Timer-Trigger-implementation

Signed-off-by: Shuah Khan <shuahkhan@...il.com>
Reviewed-by: NeilBrown <neilb@...e.de>
Cc: Richard Purdie <rpurdie@...ux.intel.com>
---
 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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