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Subject[PATCH v2 2/2] leds: Add control of the voltage/current regulator to the LED core
Date
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@ti.com>
---
drivers/leds/led-class.c | 15 ++++++++++++
drivers/leds/led-core.c | 50 +++++++++++++++++++++++++++++++++++++---
drivers/leds/leds.h | 1 +
include/linux/leds.h | 4 ++++
4 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 4793e77808e2..cadd43c30d50 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -253,6 +253,7 @@ int of_led_classdev_register(struct device *parent, struct device_node *np,
{
char name[LED_MAX_NAME_SIZE];
int ret;
+ struct regulator *regulator;

ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
if (ret < 0)
@@ -272,6 +273,20 @@ int of_led_classdev_register(struct device *parent, struct device_node *np,
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 (PTR_ERR(regulator) != -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;
+ }
+
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 7107cd7e87cf..a12b880b0a2f 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -23,6 +23,33 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
LIST_HEAD(leds_list);
EXPORT_SYMBOL_GPL(leds_list);

+static bool __led_need_regulator_update(struct led_classdev *led_cdev,
+ int brightness)
+{
+ bool new_state = (brightness != LED_OFF);
+
+ return led_cdev->regulator && led_cdev->regulator_state != new_state;
+}
+
+static int __led_handle_regulator(struct led_classdev *led_cdev,
+ int brightness)
+{
+ int rc;
+
+ if (__led_need_regulator_update(led_cdev, brightness)) {
+
+ if (brightness != LED_OFF)
+ rc = regulator_enable(led_cdev->regulator);
+ else
+ rc = regulator_disable(led_cdev->regulator);
+ if (rc)
+ return rc;
+
+ led_cdev->regulator_state = (brightness != LED_OFF);
+ }
+ return 0;
+}
+
static int __led_set_brightness(struct led_classdev *led_cdev,
enum led_brightness value)
{
@@ -80,6 +107,7 @@ static void led_timer_function(struct timer_list *t)
}

led_set_brightness_nosleep(led_cdev, brightness);
+ __led_handle_regulator(led_cdev, brightness);

/* Return in next iteration if led is in one-shot mode and we are in
* the final blink state so that the led is toggled each delay_on +
@@ -115,6 +143,8 @@ static void set_brightness_delayed(struct work_struct *ws)
if (ret == -ENOTSUPP)
ret = __led_set_brightness_blocking(led_cdev,
led_cdev->delayed_set_value);
+ __led_handle_regulator(led_cdev, led_cdev->delayed_set_value);
+
if (ret < 0 &&
/* LED HW might have been unplugged, therefore don't warn */
!(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
@@ -141,6 +171,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
/* never on - just set to off */
if (!delay_on) {
led_set_brightness_nosleep(led_cdev, LED_OFF);
+ __led_handle_regulator(led_cdev, LED_OFF);
return;
}

@@ -148,6 +179,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
if (!delay_off) {
led_set_brightness_nosleep(led_cdev,
led_cdev->blink_brightness);
+ __led_handle_regulator(led_cdev, led_cdev->blink_brightness);
return;
}

@@ -256,8 +288,14 @@ 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))
- return;
+ if (!__led_set_brightness(led_cdev, value)) {
+ /*
+ * if regulator state doesn't need to be changed, that is all/
+ * Otherwise delegate the change to a work queue
+ */
+ if (!__led_need_regulator_update(led_cdev, value))
+ return;
+ }

/* If brightness setting can sleep, delegate it to a work queue task */
led_cdev->delayed_set_value = value;
@@ -280,6 +318,8 @@ EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
int led_set_brightness_sync(struct led_classdev *led_cdev,
enum led_brightness value)
{
+ int ret;
+
if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
return -EBUSY;

@@ -288,7 +328,11 @@ int led_set_brightness_sync(struct led_classdev *led_cdev,
if (led_cdev->flags & LED_SUSPENDED)
return 0;

- return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
+ ret = __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
+ if (ret)
+ return ret;
+
+ return __led_handle_regulator(led_cdev, led_cdev->brightness);
}
EXPORT_SYMBOL_GPL(led_set_brightness_sync);

diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 47b229469069..5aa5c038bd38 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -11,6 +11,7 @@

#include <linux/rwsem.h>
#include <linux/leds.h>
+#include <linux/regulator/consumer.h>

static inline int led_get_brightness(struct led_classdev *led_cdev)
{
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 9b2bf574a17a..bee8e3f8dddd 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -123,6 +123,10 @@ struct led_classdev {

/* Ensures consistent access to the LED Flash Class device */
struct mutex led_access;
+
+ /* regulator */
+ struct regulator *regulator;
+ bool regulator_state;
};

extern int of_led_classdev_register(struct device *parent,
--
2.17.1
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