new file mode 100644
@@ -0,0 +1,16 @@
+pwm-backlight bindings
+
+Required properties:
+ - compatible: "pwm-backlight"
+ - default-brightness: the default brightness setting
+ - max-brightness: the maximum brightness setting
+ - pwm: OF device-tree PWM specification
+
+Example:
+
+ backlight {
+ compatible = "pwm-backlight";
+ default-brightness = <224>;
+ max-brightness = <255>;
+ pwm = <&pwm 0 5000000>;
+ };
@@ -233,7 +233,7 @@ config BACKLIGHT_CARILLO_RANCH
config BACKLIGHT_PWM
tristate "Generic PWM based Backlight Driver"
- depends on HAVE_PWM
+ depends on HAVE_PWM || PWM
help
If you have a LCD backlight adjustable by PWM, say Y to enable
this driver.
@@ -17,6 +17,7 @@
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/err.h>
+#include <linux/of_pwm.h>
#include <linux/pwm.h>
#include <linux/pwm_backlight.h>
#include <linux/slab.h>
@@ -31,6 +32,7 @@ struct pwm_bl_data {
void (*notify_after)(struct device *,
int brightness);
int (*check_fb)(struct device *, struct fb_info *);
+ void (*exit)(struct device *);
};
static int pwm_backlight_update_status(struct backlight_device *bl)
@@ -83,17 +85,79 @@ static const struct backlight_ops pwm_backlight_ops = {
.check_fb = pwm_backlight_check_fb,
};
+#ifdef CONFIG_OF
+static int pwm_backlight_parse_dt(struct device *dev,
+ struct platform_pwm_backlight_data *data)
+{
+ struct device_node *node = dev->of_node;
+ struct pwm_spec spec;
+ u32 value;
+ int ret;
+
+ if (!node)
+ return -ENODEV;
+
+ memset(data, 0, sizeof(*data));
+
+ ret = of_get_named_pwm(node, "pwm", 0, &spec);
+ if (ret < 0)
+ return ret;
+
+ data->pwm_period_ns = spec.period;
+ data->pwm_id = ret;
+
+ ret = of_property_read_u32(node, "default-brightness", &value);
+ if (ret < 0)
+ return ret;
+
+ data->dft_brightness = value;
+
+ ret = of_property_read_u32(node, "max-brightness", &value);
+ if (ret < 0)
+ return ret;
+
+ data->max_brightness = value;
+
+ /*
+ * TODO: Most users of this driver use a number of GPIOs to control
+ * backlight power. Support for specifying these needs to be
+ * added.
+ */
+
+ return 0;
+}
+
+static struct of_device_id pwm_backlight_of_match[] = {
+ { .compatible = "pwm-backlight" },
+ { }
+};
+
+MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
+#else
+static int pwm_backlight_parse_dt(struct device *dev,
+ struct platform_pwm_backlight_data *data)
+{
+ return -ENODEV;
+}
+#endif
+
static int pwm_backlight_probe(struct platform_device *pdev)
{
struct backlight_properties props;
struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
+ struct platform_pwm_backlight_data defdata;
struct backlight_device *bl;
struct pwm_bl_data *pb;
int ret;
if (!data) {
- dev_err(&pdev->dev, "failed to find platform data\n");
- return -EINVAL;
+ ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to find platform data\n");
+ return ret;
+ }
+
+ data = &defdata;
}
if (data->init) {
@@ -113,6 +177,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->notify = data->notify;
pb->notify_after = data->notify_after;
pb->check_fb = data->check_fb;
+ pb->exit = data->exit;
pb->lth_brightness = data->lth_brightness *
(data->pwm_period_ns / data->max_brightness);
pb->dev = &pdev->dev;
@@ -152,7 +217,6 @@ err_alloc:
static int pwm_backlight_remove(struct platform_device *pdev)
{
- struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
struct backlight_device *bl = platform_get_drvdata(pdev);
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
@@ -160,8 +224,8 @@ static int pwm_backlight_remove(struct platform_device *pdev)
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
pwm_free(pb->pwm);
- if (data->exit)
- data->exit(&pdev->dev);
+ if (pb->exit)
+ pb->exit(&pdev->dev);
return 0;
}
@@ -195,11 +259,12 @@ static SIMPLE_DEV_PM_OPS(pwm_backlight_pm_ops, pwm_backlight_suspend,
static struct platform_driver pwm_backlight_driver = {
.driver = {
- .name = "pwm-backlight",
- .owner = THIS_MODULE,
+ .name = "pwm-backlight",
+ .owner = THIS_MODULE,
#ifdef CONFIG_PM
- .pm = &pwm_backlight_pm_ops,
+ .pm = &pwm_backlight_pm_ops,
#endif
+ .of_match_table = of_match_ptr(pwm_backlight_of_match),
},
.probe = pwm_backlight_probe,
.remove = pwm_backlight_remove,
This commit adds very basic support for device tree probing. Currently, only a PWM and maximum and default brightness values can be specified. Enabling or disabling backlight power via GPIOs is not yet supported. A pointer to the exit() callback is stored in the driver data to keep it around until the driver is unloaded. Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de> --- Changes in v2: - avoid oops by keeping a reference to the platform-specific exit() callback .../bindings/video/backlight/pwm-backlight | 16 ++++ drivers/video/backlight/Kconfig | 2 +- drivers/video/backlight/pwm_bl.c | 81 ++++++++++++++++++-- 3 files changed, 90 insertions(+), 9 deletions(-) create mode 100644 Documentation/devicetree/bindings/video/backlight/pwm-backlight