linux-kernel - Re: [PATCH v3 2/2] iio: stm32 trigger: Add counter enable modes

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Date:   Sun, 2 Apr 2017 12:12:48 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        vilhelm.gray@...il.com, mwelling@...e.org
Cc:     fabrice.gasnier@...com, linaro-kernel@...ts.linaro.org,
        Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH v3 2/2] iio: stm32 trigger: Add counter enable modes

On 27/03/17 10:43, Benjamin Gaignard wrote:
> Device counting could be controlled by the level or the edges of
> a trigger.
> in_count0_enable_mode attibute allow to set the control mode.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> ---
>  .../ABI/testing/sysfs-bus-iio-timer-stm32          | 23 +++++++
>  drivers/iio/trigger/stm32-timer-trigger.c          | 70 ++++++++++++++++++++++
>  2 files changed, 93 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> index bf795ad..c0a1edc 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> @@ -59,3 +59,26 @@ Description:
>  		quadrature:
>  			Encoder A and B inputs are mixed to get direction
>  			and count with a scale of 0.25.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count_enable_mode_available
> +KernelVersion:	4.12
> +Contact:	benjamin.gaignard@...com
> +Description:
> +		Reading returns the list possible enable modes.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_count0_enable_mode
> +KernelVersion:	4.12
> +Contact:	benjamin.gaignard@...com
> +Description:
> +		Configure the device counter enable modes, in all case
> +		counting direction is set by in_count0_count_direction
> +		attribute and the counter is clocked by the internal clock.
Silly question, how does one use the encoder modes then?

> +		always:
> +			Counter is always ON.
> +
> +		gated:
> +			Counting is enabled when connected trigger signal
> +			level is high else counting is disabled.
> +
> +		triggered:
> +			Counting start on rising edge of the connected trigger.


> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 7db904c..0f1a2cf 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -353,6 +353,74 @@ static int stm32_counter_write_raw(struct iio_dev *indio_dev,
>  	.write_raw = stm32_counter_write_raw
>  };
>  
> +static const char *const stm32_enable_modes[] = {
> +	"always",
> +	"gated",
> +	"triggered",
> +};
> +
> +static int stm32_enable_mode2sms(int mode)
> +{
> +	switch (mode) {
> +	case 0:
> +		return 0;
> +	case 1:
> +		return 5;
> +	case 2:
> +		return 6;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int stm32_set_enable_mode(struct iio_dev *indio_dev,
> +				 const struct iio_chan_spec *chan,
> +				 unsigned int mode)
> +{
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	int sms = stm32_enable_mode2sms(mode);
> +
> +	if (sms < 0)
> +		return sms;
> +
> +	regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, sms);
> +
> +	return 0;
> +}
> +
> +static int stm32_sms2enable_mode(int mode)
> +{
> +	switch (mode) {
> +	case 0:
> +		return 0;
> +	case 5:
> +		return 1;
> +	case 6:
> +		return 2;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int stm32_get_enable_mode(struct iio_dev *indio_dev,
> +				 const struct iio_chan_spec *chan)
> +{
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 smcr;
> +
> +	regmap_read(priv->regmap, TIM_SMCR, &smcr);
> +	smcr &= TIM_SMCR_SMS;
> +
> +	return stm32_sms2enable_mode(smcr);
> +}
> +
> +static const struct iio_enum stm32_enable_mode_enum = {
> +	.items = stm32_enable_modes,
> +	.num_items = ARRAY_SIZE(stm32_enable_modes),
> +	.set = stm32_set_enable_mode,
> +	.get = stm32_get_enable_mode
> +};
> +
>  static const char *const stm32_quadrature_modes[] = {
>  	"channel_A",
>  	"channel_B",
> @@ -466,6 +534,8 @@ static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
>  	IIO_ENUM_AVAILABLE("count_direction", &stm32_count_direction_enum),
>  	IIO_ENUM("quadrature_mode", IIO_SEPARATE, &stm32_quadrature_mode_enum),
>  	IIO_ENUM_AVAILABLE("quadrature_mode", &stm32_quadrature_mode_enum),
> +	IIO_ENUM("enable_mode", IIO_SEPARATE, &stm32_enable_mode_enum),
> +	IIO_ENUM_AVAILABLE("enable_mode", &stm32_enable_mode_enum),
>  	{}
>  };
>  
>