[PATCH v2 3/3] led: ledtrig-transient: add support for hrtimer

David Lin
2017-09-13T17:54:00Z

This patch adds a hrtimer to ledtrig-transient so that when driver is
registered with LED_BRIGHTNESS_FAST, the hrtimer is used for the better
time accuracy in handling the duration.

Signed-off-by: David Lin <dtwlin@google.com>
---
drivers/leds/trigger/ledtrig-transient.c | 59 +++++++++++++++++++++++++++++---
1 file changed, 54 insertions(+), 5 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-transient.c b/drivers/leds/trigger/ledtrig-transient.c
index 7e6011bd3646..7d2ce757b39d 100644
--- a/drivers/leds/trigger/ledtrig-transient.c
+++ b/drivers/leds/trigger/ledtrig-transient.c
@@ -24,15 +24,18 @@
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/timer.h>
+#include <linux/hrtimer.h>
#include <linux/leds.h>
#include "../leds.h"

struct transient_trig_data {
+ struct led_classdev *led_cdev;
int activate;
int state;
int restore_state;
unsigned long duration;
struct timer_list timer;
+ struct hrtimer hrtimer;
};

static void transient_timer_function(unsigned long data)
@@ -44,6 +47,54 @@ static void transient_timer_function(unsigned long data)
led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
}

+static enum hrtimer_restart transient_hrtimer_function(struct hrtimer *timer)
+{
+ struct transient_trig_data *transient_data =
+ container_of(timer, struct transient_trig_data, hrtimer);
+
+ transient_timer_function((unsigned long)transient_data->led_cdev);
+
+ return HRTIMER_NORESTART;
+}
+
+static void transient_timer_setup(struct led_classdev *led_cdev)
+{
+ struct transient_trig_data *tdata = led_cdev->trigger_data;
+
+ if (led_cdev->flags & LED_BRIGHTNESS_FAST) {
+ tdata->led_cdev = led_cdev;
+ hrtimer_init(&tdata->hrtimer, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL);
+ tdata->hrtimer.function = transient_hrtimer_function;
+ } else {
+ setup_timer(&tdata->timer, transient_timer_function,
+ (unsigned long)led_cdev);
+ }
+}
+
+static void transient_timer_start(struct led_classdev *led_cdev)
+{
+ struct transient_trig_data *tdata = led_cdev->trigger_data;
+
+ if (led_cdev->flags & LED_BRIGHTNESS_FAST) {
+ hrtimer_start(&tdata->hrtimer, ms_to_ktime(tdata->duration),
+ HRTIMER_MODE_REL);
+ } else {
+ mod_timer(&tdata->timer,
+ jiffies + msecs_to_jiffies(tdata->duration));
+ }
+}
+
+static void transient_timer_cancel(struct led_classdev *led_cdev)
+{
+ struct transient_trig_data *tdata = led_cdev->trigger_data;
+
+ if (led_cdev->flags & LED_BRIGHTNESS_FAST)
+ hrtimer_cancel(&tdata->hrtimer);
+ else
+ del_timer_sync(&tdata->timer);
+}
+
static ssize_t transient_activate_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -70,7 +121,7 @@ static ssize_t transient_activate_store(struct device *dev,

/* cancel the running timer */
if (state == 0 && transient_data->activate == 1) {
- del_timer(&transient_data->timer);
+ transient_timer_cancel(led_cdev);
transient_data->activate = state;
led_set_brightness_nosleep(led_cdev,
transient_data->restore_state);
@@ -84,8 +135,7 @@ static ssize_t transient_activate_store(struct device *dev,
led_set_brightness_nosleep(led_cdev, transient_data->state);
transient_data->restore_state =
(transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
- mod_timer(&transient_data->timer,
- jiffies + msecs_to_jiffies(transient_data->duration));
+ transient_timer_start(led_cdev);
}

/* state == 0 && transient_data->activate == 0
@@ -182,8 +232,7 @@ static void transient_trig_activate(struct led_classdev *led_cdev)
if (rc)
goto err_out_state;

- setup_timer(&tdata->timer, transient_timer_function,
- (unsigned long) led_cdev);
+ transient_timer_setup(led_cdev);
led_cdev->activated = true;

return;
--
2.14.1.581.gf28d330327-goog