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Subject[PATCH 1/2] 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
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 | 10 ++++++++
drivers/leds/led-core.c | 53 +++++++++++++++++++++++++++++++++++++---
include/linux/leds.h | 4 +++
3 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 4793e77808e2..e01b2d982564 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -17,6 +17,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
+#include <linux/regulator/consumer.h>
#include <uapi/linux/uleds.h>
#include "leds.h"

@@ -272,6 +273,15 @@ 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));

+ led_cdev->regulator = devm_regulator_get(led_cdev->dev, "power");
+ if (IS_ERR(led_cdev->regulator)) {
+ 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(led_cdev->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..139de6b08cad 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -16,6 +16,7 @@
#include <linux/rwsem.h>
#include <linux/slab.h>
#include "leds.h"
+#include <linux/regulator/consumer.h>

DECLARE_RWSEM(leds_list_lock);
EXPORT_SYMBOL_GPL(leds_list_lock);
@@ -23,6 +24,31 @@ 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_regulator_state = (brightness != LED_OFF);
+
+ return led_cdev->regulator_state != new_regulator_state;
+}
+
+static int __led_handle_regulator(struct led_classdev *led_cdev,
+ int brightness)
+{
+ if (__led_need_regulator_update(led_cdev, brightness)) {
+ int ret;
+
+ if (brightness != LED_OFF)
+ ret = regulator_enable(led_cdev->regulator);
+ else
+ ret = regulator_disable(led_cdev->regulator);
+ if (ret)
+ return ret;
+ 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 +106,7 @@ 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 +142,8 @@ 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 +170,7 @@ 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 +178,7 @@ 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 +287,14 @@ 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 +317,8 @@ 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 +327,15 @@ 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;
+
+ ret = __led_handle_regulator(led_cdev, led_cdev->brightness);
+ if (ret)
+ return ret;
+
+ return 0;
}
EXPORT_SYMBOL_GPL(led_set_brightness_sync);

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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