iio: mma8452: Add support for transient event debouncing

Allow the debouce counter for transient events to be configured
using the sysfs attribute events/in_accel_thresh_rising_period

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index f30eb9b7a99cdec7270027d054d58ea5afe76d35..7429df3a191eb21da0705f2e0f47fb12f39ac431 100644 (file)
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -38,6 +38,7 @@
 #define MMA8452_TRANSIENT_SRC_ZTRANSE          BIT(5)
 #define MMA8452_TRANSIENT_THS 0x1f
 #define MMA8452_TRANSIENT_THS_MASK     0x7f
+#define MMA8452_TRANSIENT_COUNT 0x20
 #define MMA8452_OFF_X 0x2f
 #define MMA8452_OFF_Y 0x30
 #define MMA8452_OFF_Z 0x31
@@ -124,6 +125,12 @@ static int mma8452_get_int_plus_micros_index(const int (*vals)[2], int n,
        return -EINVAL;
 }
 
+static int mma8452_get_odr_index(struct mma8452_data *data)
+{
+       return (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
+                       MMA8452_CTRL_DR_SHIFT;
+}
+
 static const int mma8452_samp_freq[8][2] = {
        {800, 0}, {400, 0}, {200, 0}, {100, 0}, {50, 0}, {12, 500000},
        {6, 250000}, {1, 560000}
@@ -139,6 +146,18 @@ static const int mma8452_scales[3][2] = {
        {0, 9577}, {0, 19154}, {0, 38307}
 };
 
+/* Datasheet table 35  (step time vs sample frequency) */
+static const int mma8452_transient_time_step_us[8] = {
+       1250,
+       2500,
+       5000,
+       10000,
+       20000,
+       20000,
+       20000,
+       20000
+};
+
 static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
                                struct device_attribute *attr, char *buf)
 {
@@ -198,8 +217,7 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
                *val2 = mma8452_scales[i][1];
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
-               i = (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
-                       MMA8452_CTRL_DR_SHIFT;
+               i = mma8452_get_odr_index(data);
                *val = mma8452_samp_freq[i][0];
                *val2 = mma8452_samp_freq[i][1];
                return IIO_VAL_INT_PLUS_MICRO;
@@ -297,15 +315,33 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev,
                               int *val, int *val2)
 {
        struct mma8452_data *data = iio_priv(indio_dev);
-       int ret;
+       int ret, us;
 
-       ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_THS);
-       if (ret < 0)
-               return ret;
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               ret = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_THS);
+               if (ret < 0)
+                       return ret;
+
+               *val = ret & MMA8452_TRANSIENT_THS_MASK;
+               return IIO_VAL_INT;
 
-       *val = ret & MMA8452_TRANSIENT_THS_MASK;
+       case IIO_EV_INFO_PERIOD:
+               ret = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_COUNT);
+               if (ret < 0)
+                       return ret;
+
+               us = ret * mma8452_transient_time_step_us[
+                               mma8452_get_odr_index(data)];
+               *val = us / USEC_PER_SEC;
+               *val2 = us % USEC_PER_SEC;
+               return IIO_VAL_INT_PLUS_MICRO;
 
-       return IIO_VAL_INT;
+       default:
+               return -EINVAL;
+       }
 }
 
 static int mma8452_write_thresh(struct iio_dev *indio_dev,
@@ -316,9 +352,26 @@ static int mma8452_write_thresh(struct iio_dev *indio_dev,
                                int val, int val2)
 {
        struct mma8452_data *data = iio_priv(indio_dev);
+       int steps;
 
-       return mma8452_change_config(data, MMA8452_TRANSIENT_THS,
-                                    val & MMA8452_TRANSIENT_THS_MASK);
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               return mma8452_change_config(data, MMA8452_TRANSIENT_THS,
+                                            val & MMA8452_TRANSIENT_THS_MASK);
+
+       case IIO_EV_INFO_PERIOD:
+               steps = (val * USEC_PER_SEC + val2) /
+                               mma8452_transient_time_step_us[
+                                       mma8452_get_odr_index(data)];
+
+               if (steps > 0xff)
+                       return -EINVAL;
+
+               return mma8452_change_config(data, MMA8452_TRANSIENT_COUNT,
+                                            steps);
+       default:
+               return -EINVAL;
+       }
 }
 
 static int mma8452_read_event_config(struct iio_dev *indio_dev,
@@ -456,7 +509,8 @@ static const struct iio_event_spec mma8452_transient_event[] = {
                .type = IIO_EV_TYPE_THRESH,
                .dir = IIO_EV_DIR_RISING,
                .mask_separate = BIT(IIO_EV_INFO_ENABLE),
-               .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE)
+               .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
+                                       BIT(IIO_EV_INFO_PERIOD)
        },
 };