staging: iio: resolver: ad2s1210: convert fexcit to channel attribute

The ad2s1210 driver has a device-specific attribute `fexcit` for setting
the frequency of the excitation output. This converts it to a channel in
order to use standard IIO ABI.

The excitation frequency is an analog output that generates a sine wave.
Only the frequency is configurable. According to the datasheet, the
specified range of the excitation frequency is from 2 kHz to 20 kHz and
can be set in increments of 250 Hz.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-3-ec00746840fc@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index af063eb25e9c35d30e43ed8b6c74da598dd9f538..0c77727253309b0561306bd4516d5dcaf321e9f7 100644 (file)
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -227,54 +227,6 @@ static int ad2s1210_set_resolution_gpios(struct ad2s1210_state *st,
                                     bitmap);
 }
 
-static ssize_t ad2s1210_show_fexcit(struct device *dev,
-                                   struct device_attribute *attr,
-                                   char *buf)
-{
-       struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
-       unsigned int value;
-       u16 fexcit;
-       int ret;
-
-       mutex_lock(&st->lock);
-       ret = regmap_read(st->regmap, AD2S1210_REG_EXCIT_FREQ, &value);
-       if (ret < 0)
-               goto error_ret;
-
-       fexcit = value * st->clkin_hz / (1 << 15);
-
-       ret = sprintf(buf, "%u\n", fexcit);
-
-error_ret:
-       mutex_unlock(&st->lock);
-       return ret;
-}
-
-static ssize_t ad2s1210_store_fexcit(struct device *dev,
-                                    struct device_attribute *attr,
-                                    const char *buf, size_t len)
-{
-       struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
-       u16 fexcit;
-       int ret;
-
-       ret = kstrtou16(buf, 10, &fexcit);
-       if (ret < 0 || fexcit < AD2S1210_MIN_EXCIT || fexcit > AD2S1210_MAX_EXCIT)
-               return -EINVAL;
-
-       mutex_lock(&st->lock);
-       ret = ad2s1210_reinit_excitation_frequency(st, fexcit);
-       if (ret < 0)
-               goto error_ret;
-
-       ret = len;
-
-error_ret:
-       mutex_unlock(&st->lock);
-
-       return ret;
-}
-
 static ssize_t ad2s1210_show_resolution(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
@@ -478,6 +430,38 @@ static int ad2s1210_set_hysteresis(struct ad2s1210_state *st, int val)
        return ret;
 }
 
+static int ad2s1210_get_excitation_frequency(struct ad2s1210_state *st, int *val)
+{
+       unsigned int reg_val;
+       int ret;
+
+       mutex_lock(&st->lock);
+       ret = regmap_read(st->regmap, AD2S1210_REG_EXCIT_FREQ, &reg_val);
+       if (ret < 0)
+               goto error_ret;
+
+       *val = reg_val * st->clkin_hz / (1 << 15);
+       ret = IIO_VAL_INT;
+
+error_ret:
+       mutex_unlock(&st->lock);
+       return ret;
+}
+
+static int ad2s1210_set_excitation_frequency(struct ad2s1210_state *st, int val)
+{
+       int ret;
+
+       if (val < AD2S1210_MIN_EXCIT || val > AD2S1210_MAX_EXCIT)
+               return -EINVAL;
+
+       mutex_lock(&st->lock);
+       ret = ad2s1210_reinit_excitation_frequency(st, val);
+       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) */
@@ -510,6 +494,13 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
                default:
                        return -EINVAL;
                }
+       case IIO_CHAN_INFO_FREQUENCY:
+               switch (chan->type) {
+               case IIO_ALTVOLTAGE:
+                       return ad2s1210_get_excitation_frequency(st, val);
+               default:
+                       return -EINVAL;
+               }
        case IIO_CHAN_INFO_HYSTERESIS:
                switch (chan->type) {
                case IIO_ANGL:
@@ -527,9 +518,24 @@ static int ad2s1210_read_avail(struct iio_dev *indio_dev,
                               const int **vals, int *type,
                               int *length, long mask)
 {
+       static const int excitation_frequency_available[] = {
+               AD2S1210_MIN_EXCIT,
+               250, /* step */
+               AD2S1210_MAX_EXCIT,
+       };
+
        struct ad2s1210_state *st = iio_priv(indio_dev);
 
        switch (mask) {
+       case IIO_CHAN_INFO_FREQUENCY:
+               switch (chan->type) {
+               case IIO_ALTVOLTAGE:
+                       *type = IIO_VAL_INT;
+                       *vals = excitation_frequency_available;
+                       return IIO_AVAIL_RANGE;
+               default:
+                       return -EINVAL;
+               }
        case IIO_CHAN_INFO_HYSTERESIS:
                switch (chan->type) {
                case IIO_ANGL:
@@ -552,6 +558,13 @@ static int ad2s1210_write_raw(struct iio_dev *indio_dev,
        struct ad2s1210_state *st = iio_priv(indio_dev);
 
        switch (mask) {
+       case IIO_CHAN_INFO_FREQUENCY:
+               switch (chan->type) {
+               case IIO_ALTVOLTAGE:
+                       return ad2s1210_set_excitation_frequency(st, val);
+               default:
+                       return -EINVAL;
+               }
        case IIO_CHAN_INFO_HYSTERESIS:
                switch (chan->type) {
                case IIO_ANGL:
@@ -564,8 +577,6 @@ static int ad2s1210_write_raw(struct iio_dev *indio_dev,
        }
 }
 
-static IIO_DEVICE_ATTR(fexcit, 0644,
-                      ad2s1210_show_fexcit,    ad2s1210_store_fexcit, 0);
 static IIO_DEVICE_ATTR(bits, 0644,
                       ad2s1210_show_resolution, ad2s1210_store_resolution, 0);
 static IIO_DEVICE_ATTR(fault, 0644,
@@ -609,11 +620,19 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
                .channel = 0,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
-       }
+       }, {
+               /* excitation frequency output */
+               .type = IIO_ALTVOLTAGE,
+               .indexed = 1,
+               .channel = 0,
+               .output = 1,
+               .scan_index = -1,
+               .info_mask_separate = BIT(IIO_CHAN_INFO_FREQUENCY),
+               .info_mask_separate_available = BIT(IIO_CHAN_INFO_FREQUENCY),
+       },
 };
 
 static struct attribute *ad2s1210_attributes[] = {
-       &iio_dev_attr_fexcit.dev_attr.attr,
        &iio_dev_attr_bits.dev_attr.attr,
        &iio_dev_attr_fault.dev_attr.attr,
        &iio_dev_attr_los_thrd.dev_attr.attr,