linux-kernel - Re: [PATCH v3 3/3] input: pwm-beeper: add devicetree bindings to set volume levels

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Date:   Thu, 19 Jan 2017 13:30:49 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Frieder Schrempf <frieder.schrempf@...eet.de>
Cc:     robh@...nel.org, pawel.moll@....com, ijc+devicetree@...lion.org.uk,
        galak@...eaurora.org, luis@...ethencourt.com,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] input: pwm-beeper: add devicetree bindings to set
 volume levels

On Thu, Jan 19, 2017 at 04:24:10PM +0100, Frieder Schrempf wrote:
> This patch adds the devicetree bindings to set the volume levels
> and the default volume level.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...eet.de>
> ---
> Changes in v3:
>  - none
>  
>  drivers/input/misc/pwm-beeper.c | 49 ++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 46 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
> index 3ed21da..a7f9d70 100644
> --- a/drivers/input/misc/pwm-beeper.c
> +++ b/drivers/input/misc/pwm-beeper.c
> @@ -32,7 +32,7 @@ struct pwm_beeper {
>  	struct work_struct work;
>  	unsigned long period;
>  	unsigned int volume;
> -	unsigned int volume_levels[] = {0, 8, 20, 40, 500};
> +	unsigned int *volume_levels;
>  	unsigned int max_volume_level;
>  };
>  
> @@ -161,8 +161,11 @@ static void pwm_beeper_close(struct input_dev *input)
>  static int pwm_beeper_probe(struct platform_device *pdev)
>  {
>  	unsigned long pwm_id = (unsigned long)dev_get_platdata(&pdev->dev);
> +	struct device_node *np = pdev->dev.of_node;
>  	struct pwm_beeper *beeper;
> -	int error;
> +	struct property *prop;
> +	int error, length;
> +	u32 value;
>  
>  	beeper = kzalloc(sizeof(*beeper), GFP_KERNEL);
>  	if (!beeper)
> @@ -188,7 +191,47 @@ static int pwm_beeper_probe(struct platform_device *pdev)
>  
>  	INIT_WORK(&beeper->work, pwm_beeper_work);
>  
> -	beeper->max_volume_level = ARRAY_SIZE(beeper->volume_levels) - 1;
> +	/* determine the number of volume levels */
> +	prop = of_find_property(np, "volume-levels", &length);

Please use generic device properties, not OF-specific ones.

> +	if (!prop) {
> +		dev_dbg(&pdev->dev, "no volume levels specified, using max volume\n");
> +		beeper->max_volume_level = 1;
> +	} else
> +		beeper->max_volume_level = length / sizeof(u32);
> +
> +	/* read volume levels from DT property */
> +	if (beeper->max_volume_level > 0) {
> +		size_t size = sizeof(*beeper->volume_levels) *
> +			beeper->max_volume_level;
> +
> +		beeper->volume_levels = devm_kzalloc(&(pdev->dev), size,
> +			GFP_KERNEL);
> +		if (!beeper->volume_levels)
> +			return -ENOMEM;
> +
> +		if (prop) {
> +			error = of_property_read_u32_array(np, "volume-levels",
> +						beeper->volume_levels,
> +						beeper->max_volume_level);
> +
> +			if (error < 0)
> +				return error;
> +
> +			error = of_property_read_u32(np, "default-volume-level",
> +						   &value);
> +
> +			if (error < 0) {
> +				dev_dbg(&pdev->dev, "no default volume specified, using max volume\n");
> +				value = beeper->max_volume_level - 1;
> +			}
> +		} else {
> +			beeper->volume_levels[0] = 500;
> +			value = 0;
> +		}
> +
> +		beeper->volume = value;
> +		beeper->max_volume_level--;
> +	}
>  
>  	beeper->input = input_allocate_device();
>  	if (!beeper->input) {
> -- 
> 2.7.4
> 

-- 
Dmitry