iio: magn: bmc150_magn: add oversampling ratio

Export the oversampling ratio so that the user can change the
number of repetions for x/y/z axis.

The sampling frequency is limited by the oversampling ratio.
The available sampling frequencies might change depending
on the values of oversampling_ratio.

The specification can be downloaded from:
http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
index 7bbaea8..d4c1788 100644 (file)
--- a/drivers/iio/magnetometer/bmc150_magn.c
+++ b/drivers/iio/magnetometer/bmc150_magn.c
@@ -146,6 +146,7 @@ struct bmc150_magn_data {
        s32 buffer[6];
        struct iio_trigger *dready_trig;
        bool dready_trigger_on;
+       int max_odr;
 };
 
 static const struct {
@@ -323,6 +324,43 @@ static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
        return -EINVAL;
 }
 
+static int bmc150_magn_set_max_odr(struct bmc150_magn_data *data, int rep_xy,
+                                  int rep_z, int odr)
+{
+       int ret, reg_val, max_odr;
+
+       if (rep_xy <= 0) {
+               ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
+                                 &reg_val);
+               if (ret < 0)
+                       return ret;
+               rep_xy = BMC150_MAGN_REGVAL_TO_REPXY(reg_val);
+       }
+       if (rep_z <= 0) {
+               ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
+                                 &reg_val);
+               if (ret < 0)
+                       return ret;
+               rep_z = BMC150_MAGN_REGVAL_TO_REPZ(reg_val);
+       }
+       if (odr <= 0) {
+               ret = bmc150_magn_get_odr(data, &odr);
+               if (ret < 0)
+                       return ret;
+       }
+       /* the maximum selectable read-out frequency from datasheet */
+       max_odr = 1000000 / (145 * rep_xy + 500 * rep_z + 980);
+       if (odr > max_odr) {
+               dev_err(&data->client->dev,
+                       "Can't set oversampling with sampling freq %d\n",
+                       odr);
+               return -EINVAL;
+       }
+       data->max_odr = max_odr;
+
+       return 0;
+}
+
 static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
                                    u16 rhall)
 {
@@ -422,7 +460,7 @@ static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
                                int *val, int *val2, long mask)
 {
        struct bmc150_magn_data *data = iio_priv(indio_dev);
-       int ret;
+       int ret, tmp;
        s32 values[AXIS_XYZ_MAX];
 
        switch (mask) {
@@ -467,6 +505,26 @@ static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
                if (ret < 0)
                        return ret;
                return IIO_VAL_INT;
+       case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+               switch (chan->channel2) {
+               case IIO_MOD_X:
+               case IIO_MOD_Y:
+                       ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
+                                         &tmp);
+                       if (ret < 0)
+                               return ret;
+                       *val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
+                       return IIO_VAL_INT;
+               case IIO_MOD_Z:
+                       ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
+                                         &tmp);
+                       if (ret < 0)
+                               return ret;
+                       *val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
+                       return IIO_VAL_INT;
+               default:
+                       return -EINVAL;
+               }
        default:
                return -EINVAL;
        }
@@ -481,10 +539,50 @@ static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
 
        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
+               if (val > data->max_odr)
+                       return -EINVAL;
                mutex_lock(&data->mutex);
                ret = bmc150_magn_set_odr(data, val);
                mutex_unlock(&data->mutex);
                return ret;
+       case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+               switch (chan->channel2) {
+               case IIO_MOD_X:
+               case IIO_MOD_Y:
+                       if (val < 1 || val > 511)
+                               return -EINVAL;
+                       mutex_lock(&data->mutex);
+                       ret = bmc150_magn_set_max_odr(data, val, 0, 0);
+                       if (ret < 0) {
+                               mutex_unlock(&data->mutex);
+                               return ret;
+                       }
+                       ret = regmap_update_bits(data->regmap,
+                                                BMC150_MAGN_REG_REP_XY,
+                                                0xFF,
+                                                BMC150_MAGN_REPXY_TO_REGVAL
+                                                (val));
+                       mutex_unlock(&data->mutex);
+                       return ret;
+               case IIO_MOD_Z:
+                       if (val < 1 || val > 256)
+                               return -EINVAL;
+                       mutex_lock(&data->mutex);
+                       ret = bmc150_magn_set_max_odr(data, 0, val, 0);
+                       if (ret < 0) {
+                               mutex_unlock(&data->mutex);
+                               return ret;
+                       }
+                       ret = regmap_update_bits(data->regmap,
+                                                BMC150_MAGN_REG_REP_Z,
+                                                0xFF,
+                                                BMC150_MAGN_REPZ_TO_REGVAL
+                                                (val));
+                       mutex_unlock(&data->mutex);
+                       return ret;
+               default:
+                       return -EINVAL;
+               }
        default:
                return -EINVAL;
        }
@@ -501,10 +599,31 @@ static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
        return 0;
 }
 
-static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
+static ssize_t bmc150_magn_show_samp_freq_avail(struct device *dev,
+                                               struct device_attribute *attr,
+                                               char *buf)
+{
+       struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+       struct bmc150_magn_data *data = iio_priv(indio_dev);
+       size_t len = 0;
+       u8 i;
+
+       for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
+               if (bmc150_magn_samp_freq_table[i].freq > data->max_odr)
+                       break;
+               len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+                                bmc150_magn_samp_freq_table[i].freq);
+       }
+       /* replace last space with a newline */
+       buf[len - 1] = '\n';
+
+       return len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(bmc150_magn_show_samp_freq_avail);
 
 static struct attribute *bmc150_magn_attributes[] = {
-       &iio_const_attr_sampling_frequency_available.dev_attr.attr,
+       &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
        NULL,
 };
 
@@ -516,7 +635,8 @@ static const struct attribute_group bmc150_magn_attrs_group = {
        .type = IIO_MAGN,                                               \
        .modified = 1,                                                  \
        .channel2 = IIO_MOD_##_axis,                                    \
-       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                   \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |                  \
+                             BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),    \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |      \
                                    BIT(IIO_CHAN_INFO_SCALE),           \
        .scan_index = AXIS_##_axis,                                     \
@@ -616,6 +736,11 @@ static int bmc150_magn_init(struct bmc150_magn_data *data)
                goto err_poweroff;
        }
 
+       ret = bmc150_magn_set_max_odr(data, preset.rep_xy, preset.rep_z,
+                                     preset.odr);
+       if (ret < 0)
+               goto err_poweroff;
+
        ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
                                         true);
        if (ret < 0) {