linux-leds.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jean-Jacques Hiblot <jjhiblot@ti.com>
To: <jacek.anaszewski@gmail.com>, <pavel@ucw.cz>,
	<daniel.thompson@linaro.org>
Cc: <linux-leds@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<dmurphy@ti.com>, <tomi.valkeinen@ti.com>,
	Jean-Jacques Hiblot <jjhiblot@ti.com>
Subject: [PATCH v5 3/3] leds: Add control of the voltage/current regulator to the LED core
Date: Mon, 23 Sep 2019 12:20:59 +0200	[thread overview]
Message-ID: <20190923102059.17818-4-jjhiblot@ti.com> (raw)
In-Reply-To: <20190923102059.17818-1-jjhiblot@ti.com>

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 | 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


  parent reply	other threads:[~2019-09-23 10:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23 10:20 [PATCH v5 0/3] " Jean-Jacques Hiblot
2019-09-23 10:20 ` [PATCH v5 1/3] led: make led_set_brightness_sync() use led_set_brightness_nosleep() Jean-Jacques Hiblot
2019-09-23 10:20 ` [PATCH v5 2/3] dt-bindings: leds: document the "power-supply" property Jean-Jacques Hiblot
2019-09-23 10:20 ` Jean-Jacques Hiblot [this message]
2019-09-24 18:58   ` [PATCH v5 3/3] leds: Add control of the voltage/current regulator to the LED core Jacek Anaszewski
2019-09-25  8:41     ` Jean-Jacques Hiblot
2019-10-13 12:09     ` Pavel Machek
2019-10-13 16:40       ` Jacek Anaszewski
2019-10-14 10:49       ` Jean-Jacques Hiblot
2019-10-14 12:38         ` Daniel Thompson
2019-10-14 18:48           ` Jacek Anaszewski
2019-10-16  8:13             ` Jean-Jacques Hiblot
2019-10-17 19:05               ` Jacek Anaszewski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190923102059.17818-4-jjhiblot@ti.com \
    --to=jjhiblot@ti.com \
    --cc=daniel.thompson@linaro.org \
    --cc=dmurphy@ti.com \
    --cc=jacek.anaszewski@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-leds@vger.kernel.org \
    --cc=pavel@ucw.cz \
    --cc=tomi.valkeinen@ti.com \
    --subject='Re: [PATCH v5 3/3] leds: Add control of the voltage/current regulator to the LED core' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).