[PATCH v2 4/4] iio: magn: bmc150_magn: add oversampling ratio

From: Irina Tirdea
Date: Thu Apr 23 2015 - 14:34:59 EST

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@xxxxxxxxx>
---
drivers/iio/magnetometer/bmc150_magn.c | 133 ++++++++++++++++++++++++++++++++-
1 file changed, 129 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
index b8e4c90..c3f9447 100644
--- 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, \
@@ -617,6 +737,11 @@ 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) {
--
1.9.1

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