iio: accel: adxl345: Implement event scaling for ABI compliance

The ADXL345 uses a fixed threshold resolution of 62.5 mg/LSB for
event-related registers. Previously, the driver reported raw
values without a scale factor.

Implement IIO_EV_INFO_SCALE for all event types to provide the
conversion factor (0.612915 m/s^2) as required by the IIO ABI.

Consequently, remove the obsolete comment in adxl345_read_event_value()
which stated that the scale factor is not applied.

Add explicit write rejection for IIO_EV_INFO_SCALE in
adxl345_write_event_value() returning -EINVAL.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Taha Ed-Dafili <0rayn.dev@gmail.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index 96d1417d77c65daf05af97f07e98561e29641830..6c9080d88c60bde088c3a00083bfe0f0c111bc89 100644 (file)
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -213,6 +213,7 @@ static const struct iio_event_spec adxl345_events[] = {
                .dir = IIO_EV_DIR_RISING,
                .mask_shared_by_type =
                        BIT(IIO_EV_INFO_ENABLE) |
+                       BIT(IIO_EV_INFO_SCALE) |
                        BIT(IIO_EV_INFO_VALUE),
        },
        {
@@ -221,6 +222,7 @@ static const struct iio_event_spec adxl345_events[] = {
                .dir = IIO_EV_DIR_RISING,
                .mask_shared_by_type =
                        BIT(IIO_EV_INFO_ENABLE) |
+                       BIT(IIO_EV_INFO_SCALE) |
                        BIT(IIO_EV_INFO_VALUE),
        },
        {
@@ -228,7 +230,9 @@ static const struct iio_event_spec adxl345_events[] = {
                .type = IIO_EV_TYPE_GESTURE,
                .dir = IIO_EV_DIR_SINGLETAP,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
-               .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
+               .mask_shared_by_type =
+                       BIT(IIO_EV_INFO_SCALE) |
+                       BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_TIMEOUT),
        },
        {
@@ -237,6 +241,7 @@ static const struct iio_event_spec adxl345_events[] = {
                .dir = IIO_EV_DIR_DOUBLETAP,
                .mask_shared_by_type =
                        BIT(IIO_EV_INFO_ENABLE) |
+                       BIT(IIO_EV_INFO_SCALE) |
                        BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_RESET_TIMEOUT) |
                        BIT(IIO_EV_INFO_TAP2_MIN_DELAY),
@@ -276,6 +281,7 @@ static const struct iio_event_spec adxl345_fake_chan_events[] = {
                .dir = IIO_EV_DIR_FALLING,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
                .mask_shared_by_type =
+                       BIT(IIO_EV_INFO_SCALE) |
                        BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_PERIOD),
        },
@@ -285,6 +291,7 @@ static const struct iio_event_spec adxl345_fake_chan_events[] = {
                .dir = IIO_EV_DIR_FALLING,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
                .mask_shared_by_type =
+                       BIT(IIO_EV_INFO_SCALE) |
                        BIT(IIO_EV_INFO_VALUE) |
                        BIT(IIO_EV_INFO_PERIOD),
        },
@@ -1343,6 +1350,16 @@ static int adxl345_read_event_value(struct iio_dev *indio_dev,
        unsigned int tap_threshold;
        int ret;
 
+       /*
+        * The event threshold LSB is fixed at 62.5 mg/LSB
+        * 0.0625 * 9.80665 = 0.612915625 m/s^2
+        */
+       if (info == IIO_EV_INFO_SCALE) {
+               *val = 0;
+               *val2 = 612915;
+               return IIO_VAL_INT_PLUS_MICRO;
+       }
+
        switch (type) {
        case IIO_EV_TYPE_MAG:
                return adxl345_read_mag_value(st, dir, info,
@@ -1357,12 +1374,6 @@ static int adxl345_read_event_value(struct iio_dev *indio_dev,
        case IIO_EV_TYPE_GESTURE:
                switch (info) {
                case IIO_EV_INFO_VALUE:
-                       /*
-                        * The scale factor would be 62.5mg/LSB (i.e. 0xFF = 16g) but
-                        * not applied here. In context of this general purpose sensor,
-                        * what imports is rather signal intensity than the absolute
-                        * measured g value.
-                        */
                        ret = regmap_read(st->regmap, ADXL345_REG_THRESH_TAP,
                                          &tap_threshold);
                        if (ret)
@@ -1403,6 +1414,9 @@ static int adxl345_write_event_value(struct iio_dev *indio_dev,
        if (ret)
                return ret;
 
+       if (info == IIO_EV_INFO_SCALE)
+               return -EINVAL;
+
        switch (type) {
        case IIO_EV_TYPE_MAG:
                ret = adxl345_write_mag_value(st, dir, info,