[PATCH 01/20] leds: implement LED_BRIGHTNESS_FAST flag

[Stas Sergeev]

Add LED_BRIGHTNESS_FAST flag. This flag is used to mark the led drivers
that do not use waiting operations when setting led brightness and do not
use work-queue in .brightness_set op.
When this flag is not set, disallow the blink periods smaller than 10mS
(LED_SLOW_MIN_PERIOD define).

CC: Bryan Wu <cooloney@xxxxxxxxx>
CC: Richard Purdie <rpurdie@xxxxxxxxx>
CC: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
CC: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
CC: linux-leds@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx

Signed-off-by: Stas Sergeev <stsp@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/leds/led-core.c                |   30 +++++++++++++++++++-----------
 drivers/leds/led-triggers.c            |    8 +++++---
 drivers/leds/trigger/ledtrig-oneshot.c |    5 ++++-
 drivers/leds/trigger/ledtrig-timer.c   |   18 +++++++++++++-----
 include/linux/leds.h                   |   12 ++++++++++--
 5 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 9886dac..89241aa 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -25,12 +25,19 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
 LIST_HEAD(leds_list);
 EXPORT_SYMBOL_GPL(leds_list);

-static void led_set_software_blink(struct led_classdev *led_cdev,
+static int led_set_software_blink(struct led_classdev *led_cdev,
 				   unsigned long delay_on,
 				   unsigned long delay_off)
 {
 	int current_brightness;

+	if (!(led_cdev->flags & LED_BRIGHTNESS_FAST)) {
+		if (delay_on < LED_SLOW_MIN_PERIOD)
+			return -ERANGE;
+		if (delay_off < LED_SLOW_MIN_PERIOD)
+			return -ERANGE;
+	}
+
 	current_brightness = led_get_brightness(led_cdev);
 	if (current_brightness)
 		led_cdev->blink_brightness = current_brightness;
@@ -43,36 +50,37 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
 	/* never on - just set to off */
 	if (!delay_on) {
 		led_set_brightness_async(led_cdev, LED_OFF);
-		return;
+		return 0;
 	}

 	/* never off - just set to brightness */
 	if (!delay_off) {
 		led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
-		return;
+		return 0;
 	}

 	mod_timer(&led_cdev->blink_timer, jiffies + 1);
+	return 0;
 }


-static void led_blink_setup(struct led_classdev *led_cdev,
+static int led_blink_setup(struct led_classdev *led_cdev,
 		     unsigned long *delay_on,
 		     unsigned long *delay_off)
 {
 	if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
 	    led_cdev->blink_set &&
 	    !led_cdev->blink_set(led_cdev, delay_on, delay_off))
-		return;
+		return 0;

 	/* blink with 1 Hz as default if nothing specified */
 	if (!*delay_on && !*delay_off)
 		*delay_on = *delay_off = 500;

-	led_set_software_blink(led_cdev, *delay_on, *delay_off);
+	return led_set_software_blink(led_cdev, *delay_on, *delay_off);
 }

-void led_blink_set(struct led_classdev *led_cdev,
+int led_blink_set(struct led_classdev *led_cdev,
 		   unsigned long *delay_on,
 		   unsigned long *delay_off)
 {
@@ -81,18 +89,18 @@ void led_blink_set(struct led_classdev *led_cdev,
 	led_cdev->flags &= ~LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;

-	led_blink_setup(led_cdev, delay_on, delay_off);
+	return led_blink_setup(led_cdev, delay_on, delay_off);
 }
 EXPORT_SYMBOL(led_blink_set);

-void led_blink_set_oneshot(struct led_classdev *led_cdev,
+int led_blink_set_oneshot(struct led_classdev *led_cdev,
 			   unsigned long *delay_on,
 			   unsigned long *delay_off,
 			   int invert)
 {
 	if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
 	     timer_pending(&led_cdev->blink_timer))
-		return;
+		return -EBUSY;

 	led_cdev->flags |= LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
@@ -102,7 +110,7 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev,
 	else
 		led_cdev->flags &= ~LED_BLINK_INVERT;

-	led_blink_setup(led_cdev, delay_on, delay_off);
+	return led_blink_setup(led_cdev, delay_on, delay_off);
 }
 EXPORT_SYMBOL(led_blink_set_oneshot);

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index e8b1120..63305b1 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -272,6 +272,7 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
 			     int oneshot,
 			     int invert)
 {
+	int ret = 0;
 	struct led_classdev *led_cdev;

 	if (!trig)
@@ -280,12 +281,13 @@ static void led_trigger_blink_setup(struct led_trigger *trig,
 	read_lock(&trig->leddev_list_lock);
 	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
 		if (oneshot)
-			led_blink_set_oneshot(led_cdev, delay_on, delay_off,
-					      invert);
+			ret = led_blink_set_oneshot(led_cdev, delay_on,
+						   delay_off, invert);
 		else
-			led_blink_set(led_cdev, delay_on, delay_off);
+			ret = led_blink_set(led_cdev, delay_on, delay_off);
 	}
 	read_unlock(&trig->leddev_list_lock);
+	WARN_ON(ret);
 }

 void led_trigger_blink(struct led_trigger *trig,
diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index fbd02cd..ba91838 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -29,12 +29,15 @@ struct oneshot_trig_data {
 static ssize_t led_shot(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t size)
 {
+	ssize_t ret;
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;

-	led_blink_set_oneshot(led_cdev,
+	ret = led_blink_set_oneshot(led_cdev,
 			&led_cdev->blink_delay_on, &led_cdev->blink_delay_off,
 			oneshot_data->invert);
+	if (ret)
+		return ret;

 	/* content is ignored */
 	return size;
diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index 8d09327..edc0c7f 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -31,13 +31,15 @@ static ssize_t led_delay_on_store(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	unsigned long state;
-	ssize_t ret = -EINVAL;
+	ssize_t ret;

 	ret = kstrtoul(buf, 10, &state);
 	if (ret)
 		return ret;

-	led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+	ret = led_blink_set(led_cdev, &state, &led_cdev->blink_delay_off);
+	if (ret)
+		return ret;
 	led_cdev->blink_delay_on = state;

 	return size;
@@ -56,13 +58,15 @@ static ssize_t led_delay_off_store(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	unsigned long state;
-	ssize_t ret = -EINVAL;
+	ssize_t ret;

 	ret = kstrtoul(buf, 10, &state);
 	if (ret)
 		return ret;

-	led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+	ret = led_blink_set(led_cdev, &led_cdev->blink_delay_on, &state);
+	if (ret)
+		return ret;
 	led_cdev->blink_delay_off = state;

 	return size;
@@ -84,12 +88,16 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
 	if (rc)
 		goto err_out_delayon;

-	led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+	rc = led_blink_set(led_cdev, &led_cdev->blink_delay_on,
 		      &led_cdev->blink_delay_off);
+	if (rc)
+		goto err_out_delayoff;
 	led_cdev->activated = true;

 	return;

+err_out_delayoff:
+	device_remove_file(led_cdev->dev, &dev_attr_delay_off);
 err_out_delayon:
 	device_remove_file(led_cdev->dev, &dev_attr_delay_on);
 }
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b122eea..d3c6c2e 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -48,6 +48,10 @@ struct led_classdev {
 #define SET_BRIGHTNESS_ASYNC	(1 << 21)
 #define SET_BRIGHTNESS_SYNC	(1 << 22)
 #define LED_DEV_CAP_FLASH	(1 << 23)
+#define LED_BRIGHTNESS_FAST	(1 << 24)
+
+/* safe period value for slow leds is 10mS */
+#define LED_SLOW_MIN_PERIOD 10

 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
@@ -127,8 +131,10 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
  * Note that if software blinking is active, simply calling
  * led_cdev->brightness_set() will not stop the blinking,
  * use led_classdev_brightness_set() instead.
+ *
+ * Returns: 0 on success or negative error value on failure
  */
-extern void led_blink_set(struct led_classdev *led_cdev,
+extern int led_blink_set(struct led_classdev *led_cdev,
 			  unsigned long *delay_on,
 			  unsigned long *delay_off);
 /**
@@ -144,8 +150,10 @@ extern void led_blink_set(struct led_classdev *led_cdev,
  *
  * If invert is set, led blinks for delay_off first, then for
  * delay_on and leave the led on after the on-off cycle.
+ *
+ * Returns: 0 on success or negative error value on failure
  */
-extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
+extern int led_blink_set_oneshot(struct led_classdev *led_cdev,
 				  unsigned long *delay_on,
 				  unsigned long *delay_off,
 				  int invert);
-- 
1.7.9.5
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