Add support for an optional power regulator and enable/disable GPIO. This scheme is commonly used in embedded systems.
Signed-off-by: Alexandre Courbot <[email protected]> --- .../bindings/video/backlight/pwm-backlight | 4 + drivers/video/backlight/pwm_bl.c | 86 ++++++++++++++++++---- include/linux/pwm_backlight.h | 5 ++ 3 files changed, 79 insertions(+), 16 deletions(-) diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight b/Documentation/devicetree/bindings/video/backlight/pwm-backlight index 1e4fc72..85cbb7b 100644 --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight @@ -14,6 +14,8 @@ Required properties: Optional properties: - pwm-names: a list of names for the PWM devices specified in the "pwms" property (see PWM binding[0]) + - power-supply: a reference to a regulator used to control the backlight power + - enable-gpios: a reference to a GPIO used to enable/disable the backlight [0]: Documentation/devicetree/bindings/pwm/pwm.txt @@ -25,4 +27,6 @@ Example: brightness-levels = <0 4 8 16 32 64 128 255>; default-brightness-level = <6>; + power-supply = <&backlight_reg>; + enable-gpios = <&gpio 6 0>; }; diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 057389d..821e03e 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -20,6 +20,8 @@ #include <linux/pwm.h> #include <linux/pwm_backlight.h> #include <linux/slab.h> +#include <linux/of_gpio.h> +#include <linux/regulator/consumer.h> struct pwm_bl_data { struct pwm_device *pwm; @@ -27,6 +29,9 @@ struct pwm_bl_data { unsigned int period; unsigned int lth_brightness; unsigned int *levels; + bool enabled; + struct regulator *power_reg; + int enable_gpio; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *, @@ -35,6 +40,40 @@ struct pwm_bl_data { void (*exit)(struct device *); }; +static void pwm_backlight_off(struct pwm_bl_data *pb) +{ + if (!pb->enabled) + return; + + if (gpio_is_valid(pb->enable_gpio)) + gpio_set_value_cansleep(pb->enable_gpio, 0); + + if (pb->power_reg) + regulator_disable(pb->power_reg); + + pwm_config(pb->pwm, 0, pb->period); + pwm_disable(pb->pwm); + + pb->enabled = false; +} + +static void pwm_backlight_on(struct pwm_bl_data *pb, int brightness) +{ + pwm_config(pb->pwm, brightness, pb->period); + pwm_enable(pb->pwm); + + if (pb->enabled) + return; + + if (pb->power_reg) + regulator_enable(pb->power_reg); + + if (gpio_is_valid(pb->enable_gpio)) + gpio_set_value_cansleep(pb->enable_gpio, 1); + + pb->enabled = true; +} + static int pwm_backlight_update_status(struct backlight_device *bl) { struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); @@ -51,8 +90,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) brightness = pb->notify(pb->dev, brightness); if (brightness == 0) { - pwm_config(pb->pwm, 0, pb->period); - pwm_disable(pb->pwm); + pwm_backlight_off(pb); } else { if (pb->levels) { brightness = pb->levels[brightness]; @@ -61,8 +99,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) brightness = pb->lth_brightness + (brightness * (pb->period - pb->lth_brightness) / max); - pwm_config(pb->pwm, brightness, pb->period); - pwm_enable(pb->pwm); + pwm_backlight_on(pb, brightness); } if (pb->notify_after) @@ -141,11 +178,14 @@ static int pwm_backlight_parse_dt(struct device *dev, 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. - */ + ret = of_get_named_gpio(node, "enable-gpios", 0); + if (ret >= 0) { + data->enable_gpio = of_get_named_gpio(node, "enable-gpios", 0); + data->use_enable_gpio = true; + } else if (ret != -ENOENT) { + /* GPIO is optional, so ENOENT is not an error here */ + return ret; + } return 0; } @@ -176,7 +216,9 @@ static int pwm_backlight_probe(struct platform_device *pdev) if (!data) { ret = pwm_backlight_parse_dt(&pdev->dev, &defdata); - if (ret < 0) { + if (ret == -EPROBE_DEFER) { + return ret; + } else if (ret < 0) { dev_err(&pdev->dev, "failed to find platform data\n"); return ret; } @@ -221,8 +263,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) } } - dev_dbg(&pdev->dev, "got pwm for backlight\n"); - /* * The DT case will set the pwm_period_ns field to 0 and store the * period, parsed from the DT, in the PWM device. For the non-DT case, @@ -231,6 +271,22 @@ static int pwm_backlight_probe(struct platform_device *pdev) if (data->pwm_period_ns > 0) pwm_set_period(pb->pwm, data->pwm_period_ns); + + pb->power_reg = devm_regulator_get(&pdev->dev, "power"); + if (IS_ERR(pb->power_reg)) + return PTR_ERR(pb->power_reg); + + pb->enable_gpio = -EINVAL; + if (data->use_enable_gpio) { + ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio, + GPIOF_OUT_INIT_HIGH, "backlight_enable"); + if (ret) + dev_warn(&pdev->dev, + "error %d requesting control gpio\n", ret); + else + pb->enable_gpio = data->enable_gpio; + } + pb->period = pwm_get_period(pb->pwm); pb->lth_brightness = data->lth_brightness * (pb->period / max); @@ -265,8 +321,7 @@ static int pwm_backlight_remove(struct platform_device *pdev) struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); backlight_device_unregister(bl); - pwm_config(pb->pwm, 0, pb->period); - pwm_disable(pb->pwm); + pwm_backlight_off(pb); pwm_put(pb->pwm); if (pb->exit) pb->exit(&pdev->dev); @@ -281,8 +336,7 @@ 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_off(pb); 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..5ae2cd0 100644 --- a/include/linux/pwm_backlight.h +++ b/include/linux/pwm_backlight.h @@ -18,6 +18,11 @@ struct platform_pwm_backlight_data { void (*notify_after)(struct device *dev, int brightness); void (*exit)(struct device *dev); int (*check_fb)(struct device *dev, struct fb_info *info); + /* optional GPIO that enables/disables the backlight */ + int enable_gpio; + /* 0 (default initialization value) is a valid GPIO number. Make use of + * control gpio explicit to avoid bad surprises. */ + bool use_enable_gpio; }; #endif -- 1.7.11.1 -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
