[PATCHv4] video: backlight: gpio-backlight: Add DT support.

Denis Carikli
2013-10-21T09:13:33Z

Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: devicetree at vger.kernel.org
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: linux-arm-kernel at lists.infradead.org
Cc: Lothar Wa?mann <LW@KARO-electronics.de>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Eric B?nard <eric@eukrea.com>
Signed-off-by: Denis Carikli <denis@eukrea.com>
---
ChangeLog v3->v4:
- The default-brightness property is now optional, it defaults to 1 if not set.
- def_value int becomes an u32.
- gbl->def_value was set to pdata->def_value in pdata mode to avoid an extra
check.
---
.../bindings/video/backlight/gpio-backlight.txt | 20 ++++++
drivers/video/backlight/gpio_backlight.c | 69 ++++++++++++++++++--
2 files changed, 82 insertions(+), 7 deletions(-)
create mode 100644 Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt

diff --git a/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
new file mode 100644
index 0000000..3474d4a
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
@@ -0,0 +1,20 @@
+gpio-backlight bindings
+
+Required properties:
+ - compatible: "gpio-backlight"
+ - gpios: describes the gpio that is used for enabling/disabling the backlight
+ (see GPIO binding[0] for more details).
+
+Optional properties:
+ - default-brightness-level: the default brightness level (can be 0(off) or
+ 1(on) since GPIOs only support theses levels).
+
+[0]: Documentation/devicetree/bindings/gpio/gpio.txt
+
+Example:
+
+ backlight {
+ compatible = "gpio-backlight";
+ gpios = <&gpio3 4 0>;
+ default-brightness-level = <0>;
+ };
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 81fb127..248124d 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -13,6 +13,8 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
#include <linux/platform_data/gpio_backlight.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
@@ -23,6 +25,7 @@ struct gpio_backlight {

int gpio;
int active;
+ u32 def_value;
};

static int gpio_backlight_update_status(struct backlight_device *bl)
@@ -60,6 +63,41 @@ static const struct backlight_ops gpio_backlight_ops = {
.check_fb = gpio_backlight_check_fb,
};

+static int gpio_backlight_probe_dt(struct platform_device *pdev,
+ struct gpio_backlight *gbl)
+{
+ struct device_node *np = pdev->dev.of_node;
+ enum of_gpio_flags gpio_flags;
+ int ret;
+
+ gbl->fbdev = NULL;
+ gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
+
+ gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
+
+ if (gbl->gpio == -EPROBE_DEFER) {
+ return ERR_PTR(-EPROBE_DEFER);
+ } else if (gbl->gpio < 0) {
+ dev_err(&pdev->dev, "Error: gpios is a required parameter.\n");
+ return gbl->gpio;
+ }
+
+ ret = of_property_read_u32(np, "default-brightness-level",
+ &gbl->def_value);
+ if (ret < 0) {
+ /* The property is optional. */
+ gbl->def_value = 1;
+ }
+
+ if (gbl->def_value > 1) {
+ dev_warn(&pdev->dev,
+ "Warning: Invalid default-brightness-level value. Its value can be either 0(off) or 1(on).\n");
+ gbl->def_value = 1;
+ }
+
+ return 0;
+}
+
static int gpio_backlight_probe(struct platform_device *pdev)
{
struct gpio_backlight_platform_data *pdata =
@@ -67,10 +105,12 @@ static int gpio_backlight_probe(struct platform_device *pdev)
struct backlight_properties props;
struct backlight_device *bl;
struct gpio_backlight *gbl;
+ struct device_node *np = pdev->dev.of_node;
int ret;

- if (!pdata) {
- dev_err(&pdev->dev, "failed to find platform data\n");
+ if (!pdata && !np) {
+ dev_err(&pdev->dev,
+ "failed to find platform data or device tree node.\n");
return -ENODEV;
}

@@ -79,14 +119,22 @@ static int gpio_backlight_probe(struct platform_device *pdev)
return -ENOMEM;

gbl->dev = &pdev->dev;
- gbl->fbdev = pdata->fbdev;
- gbl->gpio = pdata->gpio;
- gbl->active = pdata->active_low ? 0 : 1;
+
+ if (np) {
+ ret = gpio_backlight_probe_dt(pdev, gbl);
+ if (ret)
+ return ret;
+ } else {
+ gbl->fbdev = pdata->fbdev;
+ gbl->gpio = pdata->gpio;
+ gbl->active = pdata->active_low ? 0 : 1;
+ gbl->def_value = pdata->def_value;
+ }

ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
(gbl->active ? GPIOF_INIT_LOW
: GPIOF_INIT_HIGH),
- pdata->name);
+ pdata ? pdata->name : "backlight");
if (ret < 0) {
dev_err(&pdev->dev, "unable to request GPIO\n");
return ret;
@@ -103,17 +151,24 @@ static int gpio_backlight_probe(struct platform_device *pdev)
return PTR_ERR(bl);
}

- bl->props.brightness = pdata->def_value;
+ bl->props.brightness = gbl->def_value;
+
backlight_update_status(bl);

platform_set_drvdata(pdev, bl);
return 0;
}

+static struct of_device_id gpio_backlight_of_match[] = {
+ { .compatible = "gpio-backlight" },
+ { /* sentinel */ }
+};
+
static struct platform_driver gpio_backlight_driver = {
.driver = {
.name = "gpio-backlight",
.owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(gpio_backlight_of_match),
},
.probe = gpio_backlight_probe,
};
--
1.7.9.5