[PATCH v3 18/27] staging: iio: resolver: ad2s1210: convert resolution to devicetree property

David Lechner
2023-09-29T17:26:03Z

From: David Lechner <david@lechnology.com>

From: David Lechner <dlechner@baylibre.com>

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 `adi,resolution` 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@baylibre.com>
---

v3 changes:
* Fixed multiline comment style.

drivers/staging/iio/resolver/ad2s1210.c | 136 ++++++++++++++------------------
1 file changed, 61 insertions(+), 75 deletions(-)

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index 6accb9e3db46..a0a426d0af19 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;
@@ -70,13 +77,12 @@ 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;
- 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. */
@@ -212,62 +218,6 @@ 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;
- 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)
@@ -572,8 +522,6 @@ 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);

@@ -628,7 +576,6 @@ 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,
@@ -650,15 +597,12 @@ 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)
- return 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)
@@ -698,6 +642,26 @@ 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;
+
+ return 0;
+}
+
static int ad2s1210_setup_clocks(struct ad2s1210_state *st)
{
struct device *dev = &st->sdev->dev;
@@ -719,6 +683,9 @@ 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);
@@ -736,16 +703,32 @@ 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;
}
@@ -809,7 +792,10 @@ static int ad2s1210_probe(struct spi_device *spi)

mutex_init(&st->lock);
st->sdev = spi;
- st->resolution = 12;
+
+ ret = ad2s1210_setup_properties(st);
+ if (ret < 0)
+ return ret;

ret = ad2s1210_setup_clocks(st);
if (ret < 0)

--
2.42.0