iio: accel: Add sampling rate support for STK8BA50

Added support for setting the STK8BA50 accelerometer's
sampling rate.

Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/accel/stk8ba50.c b/drivers/iio/accel/stk8ba50.c
index 3302a3d1b4bff17fc2a73ed41e7c19c05fad03a8..92229bd8c82d53986ffa88cfc57cfe3fa246a926 100644 (file)
--- a/drivers/iio/accel/stk8ba50.c
+++ b/drivers/iio/accel/stk8ba50.c
@@ -21,6 +21,7 @@
 #define STK8BA50_REG_YOUT                      0x04
 #define STK8BA50_REG_ZOUT                      0x06
 #define STK8BA50_REG_RANGE                     0x0F
+#define STK8BA50_REG_BWSEL                     0x10
 #define STK8BA50_REG_POWMODE                   0x11
 #define STK8BA50_REG_SWRST                     0x14
 
@@ -29,6 +30,7 @@
 #define STK8BA50_MODE_POWERBIT                 BIT(7)
 #define STK8BA50_DATA_SHIFT                    6
 #define STK8BA50_RESET_CMD                     0xB6
+#define STK8BA50_SR_1792HZ_IDX                 7
 
 #define STK8BA50_DRIVER_NAME                   "stk8ba50"
 
@@ -57,19 +59,30 @@ static const struct {
        {3, 38400}, {5, 76700}, {8, 153400}, {12, 306900}
 };
 
+/* Sample rates are stored as { <register value>, <Hz value> } */
+static const struct {
+       u8 reg_val;
+       u16 samp_freq;
+} stk8ba50_samp_freq_table[] = {
+       {0x08, 14},  {0x09, 25},  {0x0A, 56},  {0x0B, 112},
+       {0x0C, 224}, {0x0D, 448}, {0x0E, 896}, {0x0F, 1792}
+};
+
 struct stk8ba50_data {
        struct i2c_client *client;
        struct mutex lock;
        int range;
+       u8 sample_rate_idx;
 };
 
-#define STK8BA50_ACCEL_CHANNEL(reg, axis) {                    \
-       .type = IIO_ACCEL,                                      \
-       .address = reg,                                         \
-       .modified = 1,                                          \
-       .channel2 = IIO_MOD_##axis,                             \
-       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
-       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
+#define STK8BA50_ACCEL_CHANNEL(reg, axis) {                            \
+       .type = IIO_ACCEL,                                              \
+       .address = reg,                                                 \
+       .modified = 1,                                                  \
+       .channel2 = IIO_MOD_##axis,                                     \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
+       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),           \
+                                   BIT(IIO_CHAN_INFO_SAMP_FREQ),       \
 }
 
 static const struct iio_chan_spec stk8ba50_channels[] = {
@@ -80,8 +93,11 @@ static const struct iio_chan_spec stk8ba50_channels[] = {
 
 static IIO_CONST_ATTR(in_accel_scale_available, STK8BA50_SCALE_AVAIL);
 
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("14 25 56 112 224 448 896 1792");
+
 static struct attribute *stk8ba50_attributes[] = {
        &iio_const_attr_in_accel_scale_available.dev_attr.attr,
+       &iio_const_attr_sampling_frequency_available.dev_attr.attr,
        NULL,
 };
 
@@ -119,6 +135,11 @@ static int stk8ba50_read_raw(struct iio_dev *indio_dev,
                *val = 0;
                *val2 = stk8ba50_scale_table[data->range].scale_val;
                return IIO_VAL_INT_PLUS_MICRO;
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               *val = stk8ba50_samp_freq_table
+                               [data->sample_rate_idx].samp_freq;
+               *val2 = 0;
+               return IIO_VAL_INT;
        }
 
        return -EINVAL;
@@ -155,6 +176,25 @@ static int stk8ba50_write_raw(struct iio_dev *indio_dev,
                else
                        data->range = index;
 
+               return ret;
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               for (i = 0; i < ARRAY_SIZE(stk8ba50_samp_freq_table); i++)
+                       if (val == stk8ba50_samp_freq_table[i].samp_freq) {
+                               index = i;
+                               break;
+                       }
+               if (index < 0)
+                       return -EINVAL;
+
+               ret = i2c_smbus_write_byte_data(data->client,
+                               STK8BA50_REG_BWSEL,
+                               stk8ba50_samp_freq_table[index].reg_val);
+               if (ret < 0)
+                       dev_err(&data->client->dev,
+                                       "failed to set sampling rate\n");
+               else
+                       data->sample_rate_idx = index;
+
                return ret;
        }
 
@@ -231,6 +271,9 @@ static int stk8ba50_probe(struct i2c_client *client,
        /* The default range is +/-2g */
        data->range = 0;
 
+       /* The default sampling rate is 1792 Hz (maximum) */
+       data->sample_rate_idx = STK8BA50_SR_1792HZ_IDX;
+
        ret = iio_device_register(indio_dev);
        if (ret < 0) {
                dev_err(&client->dev, "device_register failed\n");