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 <[email protected]> --- 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 diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight b/Documentation/devicetree/bindings/video/backlight/pwm-backlight new file mode 100644 index 0000000..ce65280 --- /dev/null +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight @@ -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>; + }; diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index 49e7d83..37982fa 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -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. diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 342b7d7..5c81397 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -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, -- 1.7.9 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
