Re: [PATCH v4 04/17] staging: iio: resolver: ad2s1210: convert resolution to devicetree property

From: Jonathan Cameron
Date: Tue Oct 10 2023 - 11:43:18 EST

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On Thu, 5 Oct 2023 19:50:21 -0500
David Lechner <dlechner@xxxxxxxxxxxx> wrote:

> Selecting the resolution was implemented as the `bits` sysfs attribute.
> However, the selection of the resolution depends on how the hardware
> is wired and the specific application, so this is rather a job for
> devicetree to describe.
>
> A new devicetree property `assigned-resolution-bits` to specify the
> resolution required for each chip is added and the `bits` sysfs
> attribute is removed.
>
> Since the resolution is now supplied by a devicetree property, the
> resolution-gpios are now optional and we can allow for the case where
> the resolution pins on the AD2S1210 are hard-wired instead of requiring
> them to be connected to gpios.
>
> Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
Applied

> ---
>
> v4 changes:
> * Fixed devicetree property name in commit message.
> * Reworked handling of hysteresis_available to handle
> assigned-resolution-bits != 16.
>
> v3 changes:
> * Fixed multiline comment style.
>
> drivers/staging/iio/resolver/ad2s1210.c | 150 +++++++++++++++-----------------
> 1 file changed, 71 insertions(+), 79 deletions(-)
>
> diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> index 0c7772725330..66ef35fbb6fe 100644
> --- a/drivers/staging/iio/resolver/ad2s1210.c
> +++ b/drivers/staging/iio/resolver/ad2s1210.c
> @@ -63,6 +63,13 @@ enum ad2s1210_mode {
> MOD_CONFIG = 0b11,
> };
>
> +enum ad2s1210_resolution {
> + AD2S1210_RES_10 = 0b00,
> + AD2S1210_RES_12 = 0b01,
> + AD2S1210_RES_14 = 0b10,
> + AD2S1210_RES_16 = 0b11,
> +};
> +
> struct ad2s1210_state {
> struct mutex lock;
> struct spi_device *sdev;
> @@ -70,15 +77,14 @@ struct ad2s1210_state {
> struct gpio_desc *sample_gpio;
> /** GPIO pins connected to A0 and A1 lines. */
> struct gpio_descs *mode_gpios;
> - /** GPIO pins connected to RES0 and RES1 lines. */
> - struct gpio_descs *resolution_gpios;
> /** Used to access config registers. */
> struct regmap *regmap;
> /** The external oscillator frequency in Hz. */
> unsigned long clkin_hz;
> /** Available raw hysteresis values based on resolution. */
> int hysteresis_available[2];
> - u8 resolution;
> + /** The selected resolution */
> + enum ad2s1210_resolution resolution;
> /** For reading raw sample value via SPI. */
> __be16 sample __aligned(IIO_DMA_MINALIGN);
> /** SPI transmit buffer. */
> @@ -215,63 +221,6 @@ static int ad2s1210_reinit_excitation_frequency(struct ad2s1210_state *st,
> return regmap_write(st->regmap, AD2S1210_REG_SOFT_RESET, 0);
> }
>
> -static int ad2s1210_set_resolution_gpios(struct ad2s1210_state *st,
> - u8 resolution)
> -{
> - struct gpio_descs *gpios = st->resolution_gpios;
> - DECLARE_BITMAP(bitmap, 2);
> -
> - bitmap[0] = (resolution - 10) >> 1;
> -
> - return gpiod_set_array_value(gpios->ndescs, gpios->desc, gpios->info,
> - bitmap);
> -}
> -
> -static ssize_t ad2s1210_show_resolution(struct device *dev,
> - struct device_attribute *attr,
> - char *buf)
> -{
> - struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
> -
> - return sprintf(buf, "%d\n", st->resolution);
> -}
> -
> -static ssize_t ad2s1210_store_resolution(struct device *dev,
> - struct device_attribute *attr,
> - const char *buf, size_t len)
> -{
> - struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
> - unsigned char data;
> - unsigned char udata;
> - int ret;
> -
> - ret = kstrtou8(buf, 10, &udata);
> - if (ret || udata < 10 || udata > 16) {
> - dev_err(dev, "ad2s1210: resolution out of range\n");
> - return -EINVAL;
> - }
> -
> - data = (udata - 10) >> 1;
> -
> - mutex_lock(&st->lock);
> - ret = regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
> - AD2S1210_SET_RES, data);
> - if (ret < 0)
> - goto error_ret;
> -
> - ret = ad2s1210_set_resolution_gpios(st, udata);
> - if (ret < 0)
> - goto error_ret;
> -
> - st->resolution = udata;
> - st->hysteresis_available[1] = 1 << (16 - st->resolution);
> - ret = len;
> -
> -error_ret:
> - mutex_unlock(&st->lock);
> - return ret;
> -}
> -
> /* read the fault register since last sample */
> static ssize_t ad2s1210_show_fault(struct device *dev,
> struct device_attribute *attr, char *buf)
> @@ -413,7 +362,7 @@ static int ad2s1210_get_hysteresis(struct ad2s1210_state *st, int *val)
> if (ret < 0)
> return ret;
>
> - *val = ret << (16 - st->resolution);
> + *val = ret << (2 * (AD2S1210_RES_16 - st->resolution));
> return IIO_VAL_INT;
> }
>
> @@ -577,8 +526,6 @@ static int ad2s1210_write_raw(struct iio_dev *indio_dev,
> }
> }
>
> -static IIO_DEVICE_ATTR(bits, 0644,
> - ad2s1210_show_resolution, ad2s1210_store_resolution, 0);
> static IIO_DEVICE_ATTR(fault, 0644,
> ad2s1210_show_fault, ad2s1210_clear_fault, 0);
>
> @@ -633,7 +580,6 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
> };
>
> static struct attribute *ad2s1210_attributes[] = {
> - &iio_dev_attr_bits.dev_attr.attr,
> &iio_dev_attr_fault.dev_attr.attr,
> &iio_dev_attr_los_thrd.dev_attr.attr,
> &iio_dev_attr_dos_ovr_thrd.dev_attr.attr,
> @@ -655,15 +601,12 @@ static int ad2s1210_initial(struct ad2s1210_state *st)
> int ret;
>
> mutex_lock(&st->lock);
> - ret = ad2s1210_set_resolution_gpios(st, st->resolution);
> - if (ret < 0)
> - goto error_ret;
>
> /* Use default config register value plus resolution from devicetree. */
> data = FIELD_PREP(AD2S1210_PHASE_LOCK_RANGE_44, 1);
> data |= FIELD_PREP(AD2S1210_ENABLE_HYSTERESIS, 1);
> data |= FIELD_PREP(AD2S1210_SET_ENRES, 0x3);
> - data |= FIELD_PREP(AD2S1210_SET_RES, (st->resolution - 10) >> 1);
> + data |= FIELD_PREP(AD2S1210_SET_RES, st->resolution);
>
> ret = regmap_write(st->regmap, AD2S1210_REG_CONTROL, data);
> if (ret < 0)
> @@ -703,6 +646,35 @@ static const struct iio_info ad2s1210_info = {
> .debugfs_reg_access = &ad2s1210_debugfs_reg_access,
> };
>
> +static int ad2s1210_setup_properties(struct ad2s1210_state *st)
> +{
> + struct device *dev = &st->sdev->dev;
> + u32 val;
> + int ret;
> +
> + ret = device_property_read_u32(dev, "assigned-resolution-bits", &val);
> + if (ret < 0)
> + return dev_err_probe(dev, ret,
> + "failed to read assigned-resolution-bits property\n");
> +
> + if (val < 10 || val > 16)
> + return dev_err_probe(dev, -EINVAL,
> + "resolution out of range: %u\n", val);
> +
> + st->resolution = (val - 10) >> 1;
> + /*
> + * These are values that correlate to the hysteresis bit in the Control
> + * register. 0 = disabled, 1 = enabled. When enabled, the actual
> + * hysteresis is +/- 1 LSB of the raw position value. Which bit is the
> + * LSB depends on the specified resolution.
> + */
> + st->hysteresis_available[0] = 0;
> + st->hysteresis_available[1] = 1 << (2 * (AD2S1210_RES_16 -
> + st->resolution));
> +
> + return 0;
> +}
> +
> static int ad2s1210_setup_clocks(struct ad2s1210_state *st)
> {
> struct device *dev = &st->sdev->dev;
> @@ -724,6 +696,9 @@ static int ad2s1210_setup_clocks(struct ad2s1210_state *st)
> static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
> {
> struct device *dev = &st->sdev->dev;
> + struct gpio_descs *resolution_gpios;
> + DECLARE_BITMAP(bitmap, 2);
> + int ret;
>
> /* should not be sampling on startup */
> st->sample_gpio = devm_gpiod_get(dev, "sample", GPIOD_OUT_LOW);
> @@ -741,16 +716,32 @@ static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
> return dev_err_probe(dev, -EINVAL,
> "requires exactly 2 mode-gpios\n");
>
> - /* both pins high means that we start with 16-bit resolution */
> - st->resolution_gpios = devm_gpiod_get_array(dev, "resolution",
> - GPIOD_OUT_HIGH);
> - if (IS_ERR(st->resolution_gpios))
> - return dev_err_probe(dev, PTR_ERR(st->resolution_gpios),
> + /*
> + * If resolution gpios are provided, they get set to the required
> + * resolution, otherwise it is assumed the RES0 and RES1 pins are
> + * hard-wired to match the resolution indicated in the devicetree.
> + */
> + resolution_gpios = devm_gpiod_get_array_optional(dev, "resolution",
> + GPIOD_ASIS);
> + if (IS_ERR(resolution_gpios))
> + return dev_err_probe(dev, PTR_ERR(resolution_gpios),
> "failed to request resolution GPIOs\n");
>
> - if (st->resolution_gpios->ndescs != 2)
> - return dev_err_probe(dev, -EINVAL,
> - "requires exactly 2 resolution-gpios\n");
> + if (resolution_gpios) {
> + if (resolution_gpios->ndescs != 2)
> + return dev_err_probe(dev, -EINVAL,
> + "requires exactly 2 resolution-gpios\n");
> +
> + bitmap[0] = st->resolution;
> +
> + ret = gpiod_set_array_value(resolution_gpios->ndescs,
> + resolution_gpios->desc,
> + resolution_gpios->info,
> + bitmap);
> + if (ret < 0)
> + return dev_err_probe(dev, ret,
> + "failed to set resolution gpios\n");
> + }
>
> return 0;
> }
> @@ -814,9 +805,10 @@ static int ad2s1210_probe(struct spi_device *spi)
>
> mutex_init(&st->lock);
> st->sdev = spi;
> - st->resolution = 12;
> - st->hysteresis_available[0] = 0;
> - st->hysteresis_available[1] = 1 << (16 - st->resolution);
> +
> + ret = ad2s1210_setup_properties(st);
> + if (ret < 0)
> + return ret;
>
> ret = ad2s1210_setup_clocks(st);
> if (ret < 0)
>

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