Re: [PATCH] counter: 104-quad-8: Support Filter Clock Prescaler

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 22 Feb 2020 11:49:58 -0500
William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> The ACCES 104-QUAD-8 series does active filtering on the quadrature
> input signals via the PC/104 bus clock (OSC 14.318 MHz). This patch
> exposes the filter clock prescaler available on each channel.
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Looks good to me.  

Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to poke at it.

thanks,

Jonathan

> ---
>  .../ABI/testing/sysfs-bus-counter-104-quad-8  |  7 +++
>  drivers/counter/104-quad-8.c                  | 61 ++++++++++++++++++-
>  2 files changed, 65 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> index 46b1f33b2fce..3c905d3cf5d7 100644
> --- a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> +++ b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> @@ -1,3 +1,10 @@
> +What:		/sys/bus/counter/devices/counterX/signalY/filter_clock_prescaler
> +KernelVersion:	5.7
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Filter clock factor for input Signal Y. This prescaler value
> +		affects the inputs of both quadrature pair signals.
> +
>  What:		/sys/bus/counter/devices/counterX/signalY/index_polarity
>  KernelVersion:	5.2
>  Contact:	linux-iio@vger.kernel.org
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 17e67a84777d..0cfc813ee2cb 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -43,6 +43,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
>   */
>  struct quad8_iio {
>  	struct counter_device counter;
> +	unsigned int fck_prescaler[QUAD8_NUM_COUNTERS];
>  	unsigned int preset[QUAD8_NUM_COUNTERS];
>  	unsigned int count_mode[QUAD8_NUM_COUNTERS];
>  	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
> @@ -84,6 +85,8 @@ struct quad8_iio {
>  #define QUAD8_RLD_PRESET_CNTR 0x08
>  /* Transfer Counter to Output Latch */
>  #define QUAD8_RLD_CNTR_OUT 0x10
> +/* Transfer Preset Register LSB to FCK Prescaler */
> +#define QUAD8_RLD_PRESET_PSC 0x18
>  #define QUAD8_CHAN_OP_ENABLE_COUNTERS 0x00
>  #define QUAD8_CHAN_OP_RESET_COUNTERS 0x01
>  #define QUAD8_CMR_QUADRATURE_X1 0x08
> @@ -1140,6 +1143,50 @@ static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
>  	return len;
>  }
>  
> +static ssize_t quad8_signal_fck_prescaler_read(struct counter_device *counter,
> +	struct counter_signal *signal, void *private, char *buf)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id / 2;
> +
> +	return sprintf(buf, "%u\n", priv->fck_prescaler[channel_id]);
> +}
> +
> +static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
> +	struct counter_signal *signal, void *private, const char *buf,
> +	size_t len)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id / 2;
> +	const int base_offset = priv->base + 2 * channel_id;
> +	u8 prescaler;
> +	int ret;
> +
> +	ret = kstrtou8(buf, 0, &prescaler);
> +	if (ret)
> +		return ret;
> +
> +	priv->fck_prescaler[channel_id] = prescaler;
> +
> +	/* Reset Byte Pointer */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
> +
> +	/* Set filter clock factor */
> +	outb(prescaler, base_offset);
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
> +	     base_offset + 1);
> +
> +	return len;
> +}
> +
> +static const struct counter_signal_ext quad8_signal_ext[] = {
> +	{
> +		.name = "filter_clock_prescaler",
> +		.read = quad8_signal_fck_prescaler_read,
> +		.write = quad8_signal_fck_prescaler_write
> +	}
> +};
> +
>  static const struct counter_signal_ext quad8_index_ext[] = {
>  	COUNTER_SIGNAL_ENUM("index_polarity", &quad8_index_pol_enum),
>  	COUNTER_SIGNAL_ENUM_AVAILABLE("index_polarity",	&quad8_index_pol_enum),
> @@ -1147,9 +1194,11 @@ static const struct counter_signal_ext quad8_index_ext[] = {
>  	COUNTER_SIGNAL_ENUM_AVAILABLE("synchronous_mode", &quad8_syn_mode_enum)
>  };
>  
> -#define	QUAD8_QUAD_SIGNAL(_id, _name) {	\
> -	.id = (_id),			\
> -	.name = (_name)			\
> +#define QUAD8_QUAD_SIGNAL(_id, _name) {		\
> +	.id = (_id),				\
> +	.name = (_name),			\
> +	.ext = quad8_signal_ext,		\
> +	.num_ext = ARRAY_SIZE(quad8_signal_ext)	\
>  }
>  
>  #define	QUAD8_INDEX_SIGNAL(_id, _name) {	\
> @@ -1314,6 +1363,12 @@ static int quad8_probe(struct device *dev, unsigned int id)
>  		base_offset = base[id] + 2 * i;
>  		/* Reset Byte Pointer */
>  		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
> +		/* Reset filter clock factor */
> +		outb(0, base_offset);
> +		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
> +		     base_offset + 1);
> +		/* Reset Byte Pointer */
> +		outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
>  		/* Reset Preset Register */
>  		for (j = 0; j < 3; j++)
>  			outb(0x00, base_offset);