[PATCH] pwm: imx: Port "pwm: imx: support output polarity inversion" to Linux v4.7

[Lukasz Majewski]

Dear Lothar, Stefan,

> This patch ports "pwm: imx: support output polarity inversion" patch
> set written by Lothar Wassmann (v6 from 10.2014).
> 

I've read the e-mail from Stefan regarding missing support for pwm-imx
polarity inversion feature.

I also would like to see it in ML. Hence, my patch. Lothar, please feel
free to squash it to your patches when you (I hope :-) ) will prepare
v7 of this feature.

I hope that this would help.

Best regards,
Łukasz Majewski

> It is used to control backlight of panels via inverted PWM signal.
> 
> The "inversion" of PWM output is not an issue at such devices, since
> separate GPIO pin is responsible for enabling and disabling the
> panel's backlight.
> 
> This patch should be put on top of:
> 
> https://patchwork.kernel.org/patch/5065841/
> https://patchwork.kernel.org/patch/5065821/
> https://patchwork.kernel.org/patch/5065811/
> 
> 
> Signed-off-by: Lukasz Majewski <l.majewski at majess.pl>
> ---
>  drivers/pwm/pwm-imx.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> index 471a99e..c37d223 100644
> --- a/drivers/pwm/pwm-imx.c
> +++ b/drivers/pwm/pwm-imx.c
> @@ -181,7 +181,7 @@ static int imx_pwm_config_v2(struct pwm_chip
> *chip, if (enable)
>  		cr |= MX3_PWMCR_EN;
>  
> -	if (pwm->polarity == PWM_POLARITY_INVERSED)
> +	if (pwm->args.polarity == PWM_POLARITY_INVERSED)
>  		cr |= MX3_PWMCR_POUTC;
>  
>  	writel(cr, imx->mmio_base + MX3_PWMCR);
> @@ -201,11 +201,6 @@ static void imx_pwm_set_enable_v2(struct
> pwm_chip *chip, bool enable) else
>  		val &= ~MX3_PWMCR_EN;
>  
> -	if (chip->pwms[0].polarity == PWM_POLARITY_INVERSED)
> -		val |= MX3_PWMCR_POUTC;
> -	else
> -		val &= ~MX3_PWMCR_POUTC;
> -
>  	writel(val, imx->mmio_base + MX3_PWMCR);
>  }
>  
> @@ -253,6 +248,19 @@ static int imx_pwm_set_polarity(struct pwm_chip
> *chip, struct pwm_device *pwm, enum pwm_polarity polarity)
>  {
>  	struct imx_chip *imx = to_imx_chip(chip);
> +	u32 val;
> +
> +	if (polarity == pwm->args.polarity)
> +		return 0;
> +
> +	val = readl(imx->mmio_base + MX3_PWMCR);
> +
> +	if (polarity == PWM_POLARITY_INVERSED)
> +		val |= MX3_PWMCR_POUTC;
> +	else
> +		val &= ~MX3_PWMCR_POUTC;
> +
> +	writel(val, imx->mmio_base + MX3_PWMCR);
>  
>  	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__,
>  		polarity == PWM_POLARITY_INVERSED ? "inverted" :
> "normal");

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