This commit adds very basic support for device tree probing. Currently, only a PWM and a list of distinct brightness levels 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 v3: - use a list of distinct brightness levels instead of a linear range as discussed with Stephen Warren and Mitch Bradley Changes in v2: - avoid oops by keeping a reference to the platform-specific exit() callback TODO: - add regulator support for backlight enable/disable .../bindings/video/backlight/pwm-backlight | 19 ++++ drivers/video/backlight/Kconfig | 2 +- drivers/video/backlight/pwm_bl.c | 113 ++++++++++++++++++-- include/linux/pwm_backlight.h | 1 + 4 files changed, 124 insertions(+), 11 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..79db3dd --- /dev/null +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight @@ -0,0 +1,19 @@ +pwm-backlight bindings + +Required properties: + - compatible: "pwm-backlight" + - pwm: OF device-tree PWM specification + - num-brightness-levels: number of distinct brightness levels + - brightness-levels: array of distinct brightness levels + - default-brightness-level: the default brightness level + +Example: + + backlight { + compatible = "pwm-backlight"; + pwm = <&pwm 0 5000000>; + + num-brightness-levels = <8>; + brightness-levels = <0 4 8 16 32 64 128 255>; + default-brightness-level = <6>; + }; diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index ed68fde5..0003383 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..b65a0b6 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> @@ -26,11 +27,13 @@ struct pwm_bl_data { struct device *dev; unsigned int period; unsigned int lth_brightness; + unsigned int *levels; int (*notify)(struct device *, int brightness); 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) @@ -52,6 +55,11 @@ static int pwm_backlight_update_status(struct backlight_device *bl) pwm_config(pb->pwm, 0, pb->period); pwm_disable(pb->pwm); } else { + if (pb->levels) { + brightness = pb->levels[brightness]; + max = pb->levels[max]; + } + brightness = pb->lth_brightness + (brightness * (pb->period - pb->lth_brightness) / max); pwm_config(pb->pwm, brightness, pb->period); @@ -83,17 +91,96 @@ 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, "num-brightness-levels", &value); + if (ret < 0) + return ret; + + data->max_brightness = value; + + if (data->max_brightness > 0) { + size_t size = sizeof(*data->levels) * data->max_brightness; + + data->levels = devm_kzalloc(dev, size, GFP_KERNEL); + if (!data->levels) + return -ENOMEM; + + ret = of_property_read_u32_array(node, "brightness-levels", + data->levels, + data->max_brightness); + if (ret < 0) + return ret; + + ret = of_property_read_u32(node, "default-brightness-level", + &value); + if (ret < 0) + return ret; + + data->dft_brightness = value; + data->max_brightness--; + } + + /* + * 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; + unsigned int max; 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) { @@ -109,12 +196,18 @@ static int pwm_backlight_probe(struct platform_device *pdev) goto err_alloc; } + if (data->levels) { + max = data->levels[data->max_brightness]; + pb->levels = data->levels; + } else + max = data->max_brightness; + pb->period = data->pwm_period_ns; pb->notify = data->notify; pb->notify_after = data->notify_after; pb->check_fb = data->check_fb; - pb->lth_brightness = data->lth_brightness * - (data->pwm_period_ns / data->max_brightness); + pb->exit = data->exit; + pb->lth_brightness = data->lth_brightness * (data->pwm_period_ns / max); pb->dev = &pdev->dev; pb->pwm = pwm_request(data->pwm_id, "backlight"); @@ -152,7 +245,6 @@ 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 +252,8 @@ 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 +287,12 @@ 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, diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h index 63d2df4..56f4a86 100644 --- a/include/linux/pwm_backlight.h +++ b/include/linux/pwm_backlight.h @@ -12,6 +12,7 @@ struct platform_pwm_backlight_data { unsigned int dft_brightness; unsigned int lth_brightness; unsigned int pwm_period_ns; + unsigned int *levels; int (*init)(struct device *dev); int (*notify)(struct device *dev, int brightness); void (*notify_after)(struct device *dev, int brightness); -- 1.7.9.1 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
