linux-kernel - Re: [PATCH 4/4] iio: trigger: stm32-timer: add enable attribute

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Date:   Sun, 30 Jul 2017 14:49:19 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Fabrice Gasnier <fabrice.gasnier@...com>
Cc:     <benjamin.gaignard@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <mcoquelin.stm32@...il.com>,
        <alexandre.torgue@...com>, <benjamin.gaignard@...com>,
        <linux-iio@...r.kernel.org>, <lars@...afoo.de>, <knaack.h@....de>,
        <pmeerw@...erw.net>
Subject: Re: [PATCH 4/4] iio: trigger: stm32-timer: add enable attribute

On Thu, 27 Jul 2017 18:19:00 +0200
Fabrice Gasnier <fabrice.gasnier@...com> wrote:

> In order to use encoder mode, timers needs to be enabled (e.g. CEN bit)
> along with peripheral clock.
> Add IIO_CHAN_INFO_ENABLE attribute to handle this.
> Also, in triggered mode, CEN bit is set automatically in hardware.
> Then clock must be enabled before starting triggered mode.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
This one could perhaps have been a little more compact given
it is a fix, but it's still not huge so we'll let it go.

Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan
> ---
>  drivers/iio/trigger/stm32-timer-trigger.c | 55 +++++++++++++++++++++++--------
>  1 file changed, 41 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index d28aa02..14e6eb0 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -366,34 +366,32 @@ static int stm32_counter_read_raw(struct iio_dev *indio_dev,
>  				  int *val, int *val2, long mask)
>  {
>  	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 dat;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -	{
> -		u32 cnt;
> -
> -		regmap_read(priv->regmap, TIM_CNT, &cnt);
> -		*val = cnt;
> +		regmap_read(priv->regmap, TIM_CNT, &dat);
> +		*val = dat;
> +		return IIO_VAL_INT;
>  
> +	case IIO_CHAN_INFO_ENABLE:
> +		regmap_read(priv->regmap, TIM_CR1, &dat);
> +		*val = (dat & TIM_CR1_CEN) ? 1 : 0;
>  		return IIO_VAL_INT;
> -	}
> -	case IIO_CHAN_INFO_SCALE:
> -	{
> -		u32 smcr;
>  
> -		regmap_read(priv->regmap, TIM_SMCR, &smcr);
> -		smcr &= TIM_SMCR_SMS;
> +	case IIO_CHAN_INFO_SCALE:
> +		regmap_read(priv->regmap, TIM_SMCR, &dat);
> +		dat &= TIM_SMCR_SMS;
>  
>  		*val = 1;
>  		*val2 = 0;
>  
>  		/* in quadrature case scale = 0.25 */
> -		if (smcr == 3)
> +		if (dat == 3)
>  			*val2 = 2;
>  
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  	}
> -	}
>  
>  	return -EINVAL;
>  }
> @@ -403,6 +401,7 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
>  				   int val, int val2, long mask)
>  {
>  	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 dat;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> @@ -411,6 +410,22 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
>  	case IIO_CHAN_INFO_SCALE:
>  		/* fixed scale */
>  		return -EINVAL;
> +
> +	case IIO_CHAN_INFO_ENABLE:
> +		if (val) {
> +			regmap_read(priv->regmap, TIM_CR1, &dat);
> +			if (!(dat & TIM_CR1_CEN))
> +				clk_enable(priv->clk);
> +			regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
> +					   TIM_CR1_CEN);
> +		} else {
> +			regmap_read(priv->regmap, TIM_CR1, &dat);
> +			regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
> +					   0);
> +			if (dat & TIM_CR1_CEN)
> +				clk_disable(priv->clk);
> +		}
> +		return 0;
>  	}
>  
>  	return -EINVAL;
> @@ -506,9 +521,19 @@ static int stm32_set_enable_mode(struct iio_dev *indio_dev,
>  {
>  	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>  	int sms = stm32_enable_mode2sms(mode);
> +	u32 val;
>  
>  	if (sms < 0)
>  		return sms;
> +	/*
> +	 * Triggered mode sets CEN bit automatically by hardware. So, first
> +	 * enable counter clock, so it can use it. Keeps it in sync with CEN.
> +	 */
> +	if (sms == 6) {
> +		regmap_read(priv->regmap, TIM_CR1, &val);
> +		if (!(val & TIM_CR1_CEN))
> +			clk_enable(priv->clk);
> +	}
>  
>  	regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, sms);
>  
> @@ -681,7 +706,9 @@ static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
>  static const struct iio_chan_spec stm32_trigger_channel = {
>  	.type = IIO_COUNT,
>  	.channel = 0,
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +			      BIT(IIO_CHAN_INFO_ENABLE) |
> +			      BIT(IIO_CHAN_INFO_SCALE),
>  	.ext_info = stm32_trigger_count_info,
>  	.indexed = 1
>  };