Commit 3e7d173a authored by David Lechner's avatar David Lechner Committed by Jonathan Cameron
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staging: iio: resolver: ad2s1210: convert resolution to devicetree property 



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: default avatarDavid Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-4-ec00746840fc@baylibre.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 7dde2719

drivers/staging/iio/resolver/ad2s1210.c

+71 −79
Original line number Diff line number Diff line
@@ -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);
@@ -741,17 +716,33 @@ 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)

	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)