Re: [PATCH v2] leds: pwm: add support for default-state device property

[Denis Osterland-Heim <denis.osterland@diehl.com>]

Hi,

should be
In-Reply-To: <20200309082218.13263-1-Denis.Osterland@diehl.com>
instead of
Reply-To: <20200309082218.13263-1-Denis.Osterland@diehl.com>

Sorry

Am Dienstag, den 10.03.2020, 13:47 +0100 schrieb Denis Osterland-Heim:
> This patch adds support for "default-state" devicetree property, which
> allows to defer pwm init to first use of led.
> 
> This allows to configure the PWM early in bootloader to let the LED
> blink until an application in Linux userspace set something different.
> 
> Signed-off-by: Denis Osterland-Heim <Denis.Osterland@diehl.com>
> ---
> v1->v2:
>   - use default-state = "keep", as suggested by Jacek Anaszewski
>   - calc initial brightness with PWM state from device
> 
>  .../devicetree/bindings/leds/leds-pwm.txt     |  2 ++
>  drivers/leds/leds-pwm.c                       | 33 +++++++++++++++++--
>  include/linux/leds_pwm.h                      |  1 +
>  3 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-pwm.txt b/Documentation/devicetree/bindings/leds/leds-pwm.txt
> index 6c6583c35f2f..d0f489680594 100644
> --- a/Documentation/devicetree/bindings/leds/leds-pwm.txt
> +++ b/Documentation/devicetree/bindings/leds/leds-pwm.txt
> @@ -19,6 +19,8 @@ LED sub-node properties:
>    see Documentation/devicetree/bindings/leds/common.txt
>  - linux,default-trigger :  (optional)
>    see Documentation/devicetree/bindings/leds/common.txt
> +- default-state : (optional)
> +  see Documentation/devicetree/bindings/leds/common.yaml
>  
>  Example:
>  
> diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
> index 8b6965a563e9..92726c2e43ba 100644
> --- a/drivers/leds/leds-pwm.c
> +++ b/drivers/leds/leds-pwm.c
> @@ -75,7 +75,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
>  	led_data->active_low = led->active_low;
>  	led_data->cdev.name = led->name;
>  	led_data->cdev.default_trigger = led->default_trigger;
> -	led_data->cdev.brightness = LED_OFF;
> +	ret = led->default_state == LEDS_GPIO_DEFSTATE_ON;
> +	led_data->cdev.brightness = ret ? led->max_brightness : LED_OFF;
>  	led_data->cdev.max_brightness = led->max_brightness;
>  	led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
>  
> @@ -97,7 +98,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
>  	 * FIXME: pwm_apply_args() should be removed when switching to the
>  	 * atomic PWM API.
>  	 */
> -	pwm_apply_args(led_data->pwm);
> +	if (led->default_state != LEDS_GPIO_DEFSTATE_KEEP)
> +		pwm_apply_args(led_data->pwm);
>  
>  	pwm_get_args(led_data->pwm, &pargs);
>  
> @@ -105,10 +107,23 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
>  	if (!led_data->period && (led->pwm_period_ns > 0))
>  		led_data->period = led->pwm_period_ns;
>  
> +	if (led->default_state == LEDS_GPIO_DEFSTATE_KEEP) {
> +		uint64_t brightness;
> +		struct pwm_device *pwm = led_data->pwm;
> +		struct pwm_state state;
> +
> +		pwm->chip->ops->get_state(pwm->chip, pwm, &state);
> +		brightness = led->max_brightness * state.duty_cycle;
> +		do_div(brightness, state.period);
> +		led_data->cdev.brightness = (enum led_brightness)brightness;
> +	}
> +
>  	ret = devm_led_classdev_register(dev, &led_data->cdev);
>  	if (ret == 0) {
>  		priv->num_leds++;
> -		led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
> +		if (led->default_state != LEDS_GPIO_DEFSTATE_KEEP)
> +			led_pwm_set(&led_data->cdev,
> +					led_data->cdev.brightness);
>  	} else {
>  		dev_err(dev, "failed to register PWM led for %s: %d\n",
>  			led->name, ret);
> @@ -126,6 +141,8 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
>  	memset(&led, 0, sizeof(led));
>  
>  	device_for_each_child_node(dev, fwnode) {
> +		const char *state = NULL;
> +
>  		ret = fwnode_property_read_string(fwnode, "label", &led.name);
>  		if (ret && is_of_node(fwnode))
>  			led.name = to_of_node(fwnode)->name;
> @@ -143,6 +160,16 @@ static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
>  		fwnode_property_read_u32(fwnode, "max-brightness",
>  					 &led.max_brightness);
>  
> +		if (!fwnode_property_read_string(fwnode, "default-state",
> +						 &state)) {
> +			if (!strcmp(state, "keep"))
> +				led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
> +			else if (!strcmp(state, "on"))
> +				led.default_state = LEDS_GPIO_DEFSTATE_ON;
> +			else
> +				led.default_state = LEDS_GPIO_DEFSTATE_OFF;
> +		}
> +
>  		ret = led_pwm_add(dev, priv, &led, fwnode);
>  		if (ret) {
>  			fwnode_handle_put(fwnode);
> diff --git a/include/linux/leds_pwm.h b/include/linux/leds_pwm.h
> index 93d101d28943..c9ef9012913d 100644
> --- a/include/linux/leds_pwm.h
> +++ b/include/linux/leds_pwm.h
> @@ -10,6 +10,7 @@ struct led_pwm {
>  	const char	*default_trigger;
>  	unsigned	pwm_id __deprecated;
>  	u8 		active_low;
> +	u8		default_state;
>  	unsigned 	max_brightness;
>  	unsigned	pwm_period_ns;
>  };


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