On Thu, 5 Oct 2023 19:50:19 -0500
David Lechner <dlechner@xxxxxxxxxxxx> wrote:
> The AD2S1210 resolver has a hysteresis feature that can be used to
> prevent flicker in the LSB of the position register. This can be either
> enabled or disabled. Disabling hysteresis is useful for increasing
> precision by oversampling.
>
> Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
Applied
> ---
>
> v4 changes:
> * Fixed hysteresis raw values when st->resolution != 16.
>
> v3 changes:
> * Refactored into more functions to reduce complexity of switch statements.
> * Use early return instead of break in switch statements.
>
>
> drivers/staging/iio/resolver/ad2s1210.c | 91 +++++++++++++++++++++++++++++++--
> 1 file changed, 88 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> index 8fbde9517fe9..af063eb25e9c 100644
> --- a/drivers/staging/iio/resolver/ad2s1210.c
> +++ b/drivers/staging/iio/resolver/ad2s1210.c
> @@ -76,7 +76,8 @@ struct ad2s1210_state {
> struct regmap *regmap;
> /** The external oscillator frequency in Hz. */
> unsigned long clkin_hz;
> - bool hysteresis;
> + /** Available raw hysteresis values based on resolution. */
> + int hysteresis_available[2];
> u8 resolution;
> /** For reading raw sample value via SPI. */
> __be16 sample __aligned(IIO_DMA_MINALIGN);
> @@ -311,6 +312,7 @@ static ssize_t ad2s1210_store_resolution(struct device *dev,
> goto error_ret;
>
> st->resolution = udata;
> + st->hysteresis_available[1] = 1 << (16 - st->resolution);
> ret = len;
>
> error_ret:
> @@ -447,6 +449,35 @@ static int ad2s1210_single_conversion(struct ad2s1210_state *st,
> return ret;
> }
>
> +static int ad2s1210_get_hysteresis(struct ad2s1210_state *st, int *val)
> +{
> + int ret;
> +
> + mutex_lock(&st->lock);
> + ret = regmap_test_bits(st->regmap, AD2S1210_REG_CONTROL,
> + AD2S1210_ENABLE_HYSTERESIS);
> + mutex_unlock(&st->lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + *val = ret << (16 - st->resolution);
> + return IIO_VAL_INT;
> +}
> +
> +static int ad2s1210_set_hysteresis(struct ad2s1210_state *st, int val)
> +{
> + int ret;
> +
> + mutex_lock(&st->lock);
> + ret = regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
> + AD2S1210_ENABLE_HYSTERESIS,
> + val ? AD2S1210_ENABLE_HYSTERESIS : 0);
> + mutex_unlock(&st->lock);
> +
> + return ret;
> +}
> +
> static const int ad2s1210_velocity_scale[] = {
> 17089132, /* 8.192MHz / (2*pi * 2500 / 2^15) */
> 42722830, /* 8.192MHz / (2*pi * 1000 / 2^15) */
> @@ -479,7 +510,55 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> default:
> return -EINVAL;
> }
> + case IIO_CHAN_INFO_HYSTERESIS:
> + switch (chan->type) {
> + case IIO_ANGL:
> + return ad2s1210_get_hysteresis(st, val);
> + default:
> + return -EINVAL;
> + }
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int ad2s1210_read_avail(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + const int **vals, int *type,
> + int *length, long mask)
> +{
> + struct ad2s1210_state *st = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_HYSTERESIS:
> + switch (chan->type) {
> + case IIO_ANGL:
> + *vals = st->hysteresis_available;
> + *type = IIO_VAL_INT;
> + *length = ARRAY_SIZE(st->hysteresis_available);
> + return IIO_AVAIL_LIST;
> + default:
> + return -EINVAL;
> + }
> + default:
> + return -EINVAL;
> + }
> +}
>
> +static int ad2s1210_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct ad2s1210_state *st = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_HYSTERESIS:
> + switch (chan->type) {
> + case IIO_ANGL:
> + return ad2s1210_set_hysteresis(st, val);
> + default:
> + return -EINVAL;
> + }
> default:
> return -EINVAL;
> }
> @@ -520,7 +599,10 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
> .indexed = 1,
> .channel = 0,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> - BIT(IIO_CHAN_INFO_SCALE),
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_HYSTERESIS),
> + .info_mask_separate_available =
> + BIT(IIO_CHAN_INFO_HYSTERESIS),
> }, {
> .type = IIO_ANGL_VEL,
> .indexed = 1,
> @@ -596,6 +678,8 @@ static int ad2s1210_debugfs_reg_access(struct iio_dev *indio_dev,
>
> static const struct iio_info ad2s1210_info = {
> .read_raw = ad2s1210_read_raw,
> + .read_avail = ad2s1210_read_avail,
> + .write_raw = ad2s1210_write_raw,
> .attrs = &ad2s1210_attribute_group,
> .debugfs_reg_access = &ad2s1210_debugfs_reg_access,
> };
> @@ -711,8 +795,9 @@ static int ad2s1210_probe(struct spi_device *spi)
>
> mutex_init(&st->lock);
> st->sdev = spi;
> - st->hysteresis = true;
> st->resolution = 12;
> + st->hysteresis_available[0] = 0;
> + st->hysteresis_available[1] = 1 << (16 - st->resolution);
>
> ret = ad2s1210_setup_clocks(st);
> if (ret < 0)
>
