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Subject[PATCH 1/1 v3] pwm_bl: Add support for backlight enable regulator
Date
The backlight enable regulator is specified in the device tree node for
backlight.

Signed-off-by: Andrew Chew <achew@nvidia.com>
---
Applied all recommendations from Thierry Reding and Alex Courbot, including
making pwm_bl take an optional regulator instead of a GPIO, which solves
the platform data issue (platform data will default the regulator to NULL,
which is the right thing).

.../bindings/video/backlight/pwm-backlight.txt | 1 +
drivers/video/backlight/pwm_bl.c | 53 +++++++++++++++++---
include/linux/pwm_backlight.h | 1 +
3 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..e0bccd30 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,7 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
"pwms" property (see PWM binding[0])
+ - en-supply: phandle to the regulator device tree node

[0]: Documentation/devicetree/bindings/pwm/pwm.txt

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..c4da5e2 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
#include <linux/pwm.h>
#include <linux/pwm_backlight.h>
#include <linux/slab.h>
+#include <linux/regulator/consumer.h>

struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ struct regulator *en_supply;
+ bool en_supply_enabled;
unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
@@ -35,6 +38,34 @@ struct pwm_bl_data {
void (*exit)(struct device *);
};

+static void pwm_backlight_enable(struct backlight_device *bl)
+{
+ struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+ pwm_enable(pb->pwm);
+
+ if (pb->en_supply && !pb->en_supply_enabled) {
+ if (regulator_enable(pb->en_supply) != 0)
+ dev_warn(&bl->dev, "Failed to enable regulator");
+ else
+ pb->en_supply_enabled = true;
+ }
+}
+
+static void pwm_backlight_disable(struct backlight_device *bl)
+{
+ struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+ if (pb->en_supply && pb->en_supply_enabled) {
+ if (regulator_disable(pb->en_supply) != 0)
+ dev_warn(&bl->dev, "Failed to disable regulator");
+ else
+ pb->en_supply_enabled = false;
+ }
+
+ pwm_disable(pb->pwm);
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
@@ -52,7 +83,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)

if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_backlight_disable(bl);
} else {
int duty_cycle;

@@ -66,7 +97,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
duty_cycle = pb->lth_brightness +
(duty_cycle * (pb->period - pb->lth_brightness) / max);
pwm_config(pb->pwm, duty_cycle, pb->period);
- pwm_enable(pb->pwm);
+ pwm_backlight_enable(bl);
}

if (pb->notify_after)
@@ -146,10 +177,17 @@ static int pwm_backlight_parse_dt(struct device *dev,
}

/*
- * TODO: Most users of this driver use a number of GPIOs to control
- * backlight power. Support for specifying these needs to be
- * added.
+ * If "en-supply" is present, use that regulator to enable the
+ * backlight. If a GPIO is used to enable the backlight, make
+ * a fixed regulator with that particular GPIO and use that
+ * regulator for "en-supply".
*/
+ data->en_supply = devm_regulator_get(dev, "en");
+ if (IS_ERR_OR_NULL(data->en_supply)) {
+ ret = PTR_ERR(data->en_supply);
+ data->en_supply = NULL;
+ return ret;
+ }

return 0;
}
@@ -207,6 +245,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
} else
max = data->max_brightness;

+ pb->en_supply = data->en_supply;
pb->notify = data->notify;
pb->notify_after = data->notify_after;
pb->check_fb = data->check_fb;
@@ -268,7 +307,7 @@ static int pwm_backlight_remove(struct platform_device *pdev)

backlight_device_unregister(bl);
pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_backlight_disable(bl);
if (pb->exit)
pb->exit(&pdev->dev);
return 0;
@@ -283,7 +322,7 @@ static int pwm_backlight_suspend(struct device *dev)
if (pb->notify)
pb->notify(pb->dev, 0);
pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_backlight_disable(bl);
if (pb->notify_after)
pb->notify_after(pb->dev, 0);
return 0;
diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h
index 56f4a86..330512b 100644
--- a/include/linux/pwm_backlight.h
+++ b/include/linux/pwm_backlight.h
@@ -8,6 +8,7 @@

struct platform_pwm_backlight_data {
int pwm_id;
+ struct regulator *en_supply;
unsigned int max_brightness;
unsigned int dft_brightness;
unsigned int lth_brightness;
--
1.7.9.5


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