A LED is usually powered by a voltage/current regulator. Let the LED core
know about it. This allows the LED core to turn on or off the power supply
as needed.
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx>
---
drivers/leds/led-class.c | 17 +++++++++++
drivers/leds/led-core.c | 65 ++++++++++++++++++++++++++++++++++++++--
drivers/leds/leds.h | 3 ++
include/linux/leds.h | 5 ++++
4 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index e11177d77b4c..d122b6982efd 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -352,6 +352,7 @@ int led_classdev_register_ext(struct device *parent,
char final_name[LED_MAX_NAME_SIZE];
const char *proposed_name = composed_name;
int ret;
+ struct regulator *regulator;
if (init_data) {
if (init_data->devname_mandatory && !init_data->devicename) {
@@ -387,6 +388,22 @@ int led_classdev_register_ext(struct device *parent,
dev_warn(parent, "Led %s renamed to %s due to name collision",
led_cdev->name, dev_name(led_cdev->dev));
+ regulator = devm_regulator_get_optional(led_cdev->dev, "power");
+ if (IS_ERR(regulator)) {
+ if (regulator != ERR_PTR(-ENODEV)) {
+ dev_err(led_cdev->dev, "Cannot get the power supply for %s\n",
+ led_cdev->name);
+ device_unregister(led_cdev->dev);
+ mutex_unlock(&led_cdev->led_access);
+ return PTR_ERR(regulator);
+ }
+ led_cdev->regulator = NULL;
+ } else {
+ led_cdev->regulator = regulator;
+ led_cdev->regulator_state = REG_OFF;
+ atomic_set(&led_cdev->target_regulator_state, REG_UNKNOWN);
+ }
+
if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
ret = led_add_brightness_hw_changed(led_cdev);
if (ret) {
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index d318f9b0382d..155a158c7b8d 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -37,6 +37,43 @@ const char * const led_colors[LED_COLOR_ID_MAX] = {
};
EXPORT_SYMBOL_GPL(led_colors);
+static int __led_handle_regulator(struct led_classdev *led_cdev)
+{
+ int rc;
+ int target_state = led_cdev->delayed_set_value ? REG_ON : REG_OFF;
+
+ if (!led_cdev->regulator)
+ return 0;
+
+ /*
+ * if the current regulator state is not the target state, we
+ * need to update it.
+ * note: No need for spinlock or atomic here because
+ * led_cdev->regulator_state is modified only in the context of
+ * the worqueue
+ */
+ if (led_cdev->regulator_state != target_state) {
+
+ if (target_state == REG_ON)
+ rc = regulator_enable(led_cdev->regulator);
+ else
+ rc = regulator_disable(led_cdev->regulator);
+ if (rc) {
+ /*
+ * If something went wrong with the regulator update,
+ * Make sure that led_set_brightness_nosleep() assume
+ * that the regultor is in the right state.
+ */
+ atomic_set(&led_cdev->target_regulator_state,
+ REG_UNKNOWN);
+ return rc;
+ }
+
+ led_cdev->regulator_state = target_state;
+ }
+ return 0;
+}
+
static int __led_set_brightness(struct led_classdev *led_cdev,
enum led_brightness value)
{
@@ -135,6 +172,11 @@ static void set_brightness_delayed(struct work_struct *ws)
(led_cdev->flags & LED_HW_PLUGGABLE)))
dev_err(led_cdev->dev,
"Setting an LED's brightness failed (%d)\n", ret);
+
+ ret = __led_handle_regulator(led_cdev);
+ if (ret)
+ dev_err(led_cdev->dev,
+ "Updating regulator state failed (%d)\n", ret);
}
static void led_set_software_blink(struct led_classdev *led_cdev,
@@ -269,8 +311,27 @@ EXPORT_SYMBOL_GPL(led_set_brightness);
void led_set_brightness_nopm(struct led_classdev *led_cdev,
enum led_brightness value)
{
- /* Use brightness_set op if available, it is guaranteed not to sleep */
- if (!__led_set_brightness(led_cdev, value))
+ bool update_regulator = false;
+ int old, new;
+
+ if (led_cdev->regulator) {
+ /*
+ * Check if the regulator need to be updated.
+ * We use an atomic here because multiple threads could
+ * be calling this function at the same time. Using
+ * atomic_xchg() ensures the consistency between
+ * target_regulator_state, value and update_regulator
+ */
+ new = !!value;
+ old = atomic_xchg(&led_cdev->target_regulator_state, new);
+ update_regulator = (old != new);
+ }
+
+ /*
+ * If regulator state doesn't need to be changed, use brightness_set
+ * op if available, it is guaranteed not to sleep
+ */
+ if (!update_regulator && !__led_set_brightness(led_cdev, value))
return;
/* If brightness setting can sleep, delegate it to a work queue task */
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 0b577cece8f7..02f261ce77f2 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -11,6 +11,9 @@
#include <linux/rwsem.h>
#include <linux/leds.h>
+#include <linux/regulator/consumer.h>
+
+enum { REG_OFF = 0, REG_ON, REG_UNKNOWN };
static inline int led_get_brightness(struct led_classdev *led_cdev)
{
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 88bf2ceaabe6..8ce7cf937192 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -149,6 +149,11 @@ struct led_classdev {
/* Ensures consistent access to the LED Flash Class device */
struct mutex led_access;
+
+ /* regulator */
+ struct regulator *regulator;
+ int regulator_state;
+ atomic_t target_regulator_state;
};
/**
--
2.17.1
