Add delay_unit device attr to specify the timer delay unit.
Implement the following delay units to led trigger timer:
'nsec' for nanosecond delay_unit
'usec' for microsecond delay_unit
'msec' for millisecond delay_unit
The default is 'msec' for backward compatibility.
echo usec > /sys/class/leds/<led>/delay_unit
will specify microsecond delay unit.
Similarly you can do
echo u > /sys/class/leds/<led>/delay_unit
for a shorter notation.
This functionality is needed for things like PWM for software
brightness control, because the default mS resolution is not enough
for that tasks.
CC: Bryan Wu <coolo...@gmail.com>
CC: Richard Purdie <rpur...@rpsys.net>
CC: Jacek Anaszewski <j.anaszewsk...@gmail.com>
CC: linux-l...@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Stas Sergeev <s...@users.sourceforge.net>
---
drivers/leds/led-class.c | 18 +++++++-
drivers/leds/trigger/ledtrig-timer.c | 77 ++++++++++++++++++++++++++++++++++
include/linux/leds.h | 7 ++++
3 files changed, 100 insertions(+), 2 deletions(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index f95ce912..602d823 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -108,6 +108,7 @@ static enum hrtimer_restart led_timer_function(struct
hrtimer *timer)
struct led_classdev, blink_timer);
unsigned long brightness;
unsigned long delay;
+ ktime_t k_delay;
if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
led_set_brightness_async(led_cdev, LED_OFF);
@@ -149,9 +150,22 @@ static enum hrtimer_restart led_timer_function(struct
hrtimer *timer)
}
}
+ switch (led_cdev->delay_unit) {
+ case LED_BLINK_DU_MS:
+ k_delay = ms_to_ktime(delay);
+ break;
+ case LED_BLINK_DU_US:
+ k_delay = ns_to_ktime(delay * 1000);
+ break;
+ case LED_BLINK_DU_NS:
+ k_delay = ns_to_ktime(delay);
+ break;
+ default:
+ /* should not happen */
+ return HRTIMER_NORESTART;
+ }
hrtimer_forward(&led_cdev->blink_timer,
- hrtimer_get_expires(&led_cdev->blink_timer),
- ms_to_ktime(delay));
+ hrtimer_get_expires(&led_cdev->blink_timer), k_delay);
return HRTIMER_RESTART;
}
diff --git a/drivers/leds/trigger/ledtrig-timer.c
b/drivers/leds/trigger/ledtrig-timer.c
index 8d09327..2838178 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -68,8 +68,73 @@ static ssize_t led_delay_off_store(struct device *dev,
return size;
}
+#ifdef CONFIG_HIGH_RES_TIMERS
+static ssize_t led_dunit_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ static const char * const delay_units[] = {
+ [LED_BLINK_DU_MS] = "msec",
+ [LED_BLINK_DU_US] = "usec",
+ [LED_BLINK_DU_NS] = "nsec",
+ };
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ int ret = 0;
+ int i, max;
+
+ max = hrtimer_is_hres_active(&led_cdev->blink_timer) ?
+ LED_BLINK_DU_NS : LED_BLINK_DU_MS;
+ for (i = 0; i <= max; i++) {
+ char fmt[16];
+
+ if (led_cdev->delay_unit == i)
+ strcpy(fmt, "[%s]");
+ else
+ strcpy(fmt, "%s");
+ if (i < max)
+ strcat(fmt, " ");
+ else
+ strcat(fmt, "\n");
+ ret += sprintf(buf + ret, fmt, delay_units[i]);
+ }
+ return ret;
+}
+
+static ssize_t led_dunit_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ int ret = strlen(buf);
+
+ /* char and \n */
+ if (ret < 2)
+ return -EINVAL;
+
+ switch (buf[0]) {
+ case 'm':
+ led_cdev->delay_unit = LED_BLINK_DU_MS;
+ break;
+ case 'u':
+ led_cdev->delay_unit = LED_BLINK_DU_US;
+ break;
+ case 'n':
+ led_cdev->delay_unit = LED_BLINK_DU_NS;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+ &led_cdev->blink_delay_off);
+
+ return ret;
+}
+#endif
+
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);
+#ifdef CONFIG_HIGH_RES_TIMERS
+static DEVICE_ATTR(delay_unit, 0644, led_dunit_show, led_dunit_store);
+#endif
static void timer_trig_activate(struct led_classdev *led_cdev)
{
@@ -83,6 +148,11 @@ static void timer_trig_activate(struct led_classdev
*led_cdev)
rc = device_create_file(led_cdev->dev, &dev_attr_delay_off);
if (rc)
goto err_out_delayon;
+#ifdef CONFIG_HIGH_RES_TIMERS
+ rc = device_create_file(led_cdev->dev, &dev_attr_delay_unit);
+ if (rc)
+ goto err_out_delayoff;
+#endif
led_blink_set(led_cdev, &led_cdev->blink_delay_on,
&led_cdev->blink_delay_off);
@@ -90,6 +160,10 @@ static void timer_trig_activate(struct led_classdev
*led_cdev)
return;
+#ifdef CONFIG_HIGH_RES_TIMERS
+err_out_delayoff:
+ device_remove_file(led_cdev->dev, &dev_attr_delay_off);
+#endif
err_out_delayon:
device_remove_file(led_cdev->dev, &dev_attr_delay_on);
}
@@ -99,6 +173,9 @@ static void timer_trig_deactivate(struct led_classdev
*led_cdev)
if (led_cdev->activated) {
device_remove_file(led_cdev->dev, &dev_attr_delay_on);
device_remove_file(led_cdev->dev, &dev_attr_delay_off);
+#ifdef CONFIG_HIGH_RES_TIMERS
+ device_remove_file(led_cdev->dev, &dev_attr_delay_unit);
+#endif
led_cdev->activated = false;
}
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 68f5a23..d6bc30f 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -30,6 +30,12 @@ enum led_brightness {
LED_FULL = 255,
};
+enum led_blink_delay_unit {
+ LED_BLINK_DU_MS,
+ LED_BLINK_DU_US,
+ LED_BLINK_DU_NS,
+};
+
struct led_classdev {
const char *name;
enum led_brightness brightness;
@@ -82,6 +88,7 @@ struct led_classdev {
unsigned long blink_delay_on, blink_delay_off;
struct hrtimer blink_timer;
+ enum led_blink_delay_unit delay_unit;
int blink_brightness;
void (*flash_resume)(struct led_classdev *led_cdev);
--
1.7.9.5
--
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