iio: adc: ad9467: don't allow reading vref if not available

If there's only one possible scale, there's no way to change the Vref
select in the device so avoid reading the register in ad9467_get_scale().
In this case, it makes no sense to provide the .read_available()
callback nor allowing for writing the scale attribute.

Note this is in preparation for supporting a new device that only has
one possible scale.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240704-dev-iio-ad9467-new-devs-v1-3-f1adfee921f7@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index 077c3a594bfc4a017895ffcfd4bf1442470cf36f..d645c3b757f8cdbc4835ccc09cf19c44b9d3b130 100644 (file)
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -231,14 +231,14 @@ static void __ad9467_get_scale(struct ad9467_state *st, int index,
        *val2 = tmp % 1000000;
 }
 
-#define AD9467_CHAN(_chan, _si, _bits, _sign)                          \
+#define AD9467_CHAN(_chan, avai_mask, _si, _bits, _sign)               \
 {                                                                      \
        .type = IIO_VOLTAGE,                                            \
        .indexed = 1,                                                   \
        .channel = _chan,                                               \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |          \
                BIT(IIO_CHAN_INFO_SAMP_FREQ),                           \
-       .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE), \
+       .info_mask_shared_by_type_available = avai_mask,                \
        .scan_index = _si,                                              \
        .scan_type = {                                                  \
                .sign = _sign,                                          \
@@ -248,11 +248,11 @@ static void __ad9467_get_scale(struct ad9467_state *st, int index,
 }
 
 static const struct iio_chan_spec ad9434_channels[] = {
-       AD9467_CHAN(0, 0, 12, 's'),
+       AD9467_CHAN(0, BIT(IIO_CHAN_INFO_SCALE), 0, 12, 's'),
 };
 
 static const struct iio_chan_spec ad9467_channels[] = {
-       AD9467_CHAN(0, 0, 16, 's'),
+       AD9467_CHAN(0, BIT(IIO_CHAN_INFO_SCALE), 0, 16, 's'),
 };
 
 static const struct ad9467_chip_info ad9467_chip_tbl = {
@@ -301,9 +301,14 @@ static const struct ad9467_chip_info ad9265_chip_tbl = {
 static int ad9467_get_scale(struct ad9467_state *st, int *val, int *val2)
 {
        const struct ad9467_chip_info *info = st->info;
-       unsigned int i, vref_val;
+       unsigned int vref_val;
+       unsigned int i = 0;
        int ret;
 
+       /* nothing to read if we only have one possible scale */
+       if (info->num_scales == 1)
+               goto out_get_scale;
+
        ret = ad9467_spi_read(st, AN877_ADC_REG_VREF);
        if (ret < 0)
                return ret;
@@ -318,6 +323,7 @@ static int ad9467_get_scale(struct ad9467_state *st, int *val, int *val2)
        if (i == info->num_scales)
                return -ERANGE;
 
+out_get_scale:
        __ad9467_get_scale(st, i, val, val2);
 
        return IIO_VAL_INT_PLUS_MICRO;
@@ -332,6 +338,8 @@ static int ad9467_set_scale(struct ad9467_state *st, int val, int val2)
 
        if (val != 0)
                return -EINVAL;
+       if (info->num_scales == 1)
+               return -EOPNOTSUPP;
 
        for (i = 0; i < info->num_scales; i++) {
                __ad9467_get_scale(st, i, &scale_val[0], &scale_val[1]);
@@ -730,7 +738,7 @@ static int ad9467_update_scan_mode(struct iio_dev *indio_dev,
        return 0;
 }
 
-static const struct iio_info ad9467_info = {
+static struct iio_info ad9467_info = {
        .read_raw = ad9467_read_raw,
        .write_raw = ad9467_write_raw,
        .update_scan_mode = ad9467_update_scan_mode,
@@ -905,6 +913,8 @@ static int ad9467_probe(struct spi_device *spi)
                return -ENODEV;
        }
 
+       if (st->info->num_scales > 1)
+               ad9467_info.read_avail = ad9467_read_avail;
        indio_dev->name = st->info->name;
        indio_dev->channels = st->info->channels;
        indio_dev->num_channels = st->info->num_channels;