[PATCH V2 6/8] io: mma8452: Add highpass filter configuration.

[Martin Fuzzey <mfuzzey@parkeon.com>]

Allow the cutoff frequency of the high pass filter to be configured.

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
---
 drivers/iio/accel/mma8452.c |   65 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 1d1e41b..eb68f9a 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -29,6 +29,8 @@
 #define MMA8452_INT_SRC 0x0c
 #define MMA8452_WHO_AM_I 0x0d
 #define MMA8452_DATA_CFG 0x0e
+#define MMA8452_HP_FILTER_CUTOFF 0x0f
+#define MMA8452_HP_FILTER_CUTOFF_SEL_MASK	(BIT(0) | BIT(1))
 #define MMA8452_TRANSIENT_CFG 0x1d
 #define MMA8452_TRANSIENT_CFG_ELE		BIT(4)
 #define MMA8452_TRANSIENT_CFG_CHAN_MASK(chan)	(BIT(1) << chan)
@@ -162,6 +164,18 @@ static const int mma8452_transient_time_step_us[8] = {
 	20000
 };
 
+/* Datasheet table 18 (normal mode) */
+static const int mma8452_hp_filter_cutoff[8][4][2] = {
+	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },		/* 800 Hz sample */
+	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },		/* 400 Hz sample */
+	{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },		/* 200 Hz sample */
+	{ {4, 0}, {2, 0}, {1, 0}, {0, 500000} },	/* 100 Hz sample */
+	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },	/* 50 Hz sample */
+	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },	/* 12.5 Hz sample */
+	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },	/* 6.25 Hz sample */
+	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }	/* 1.56 Hz sample */
+};
+
 static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
@@ -176,9 +190,22 @@ static ssize_t mma8452_show_scale_avail(struct device *dev,
 		ARRAY_SIZE(mma8452_scales));
 }
 
+static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int i = mma8452_get_odr_index(data);
+
+	return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[i],
+		ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));
+}
+
 static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
 static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
 	mma8452_show_scale_avail, NULL, 0);
+static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,
+			S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0);
 
 static int mma8452_get_samp_freq_index(struct mma8452_data *data,
 	int val, int val2)
@@ -194,6 +221,15 @@ static int mma8452_get_scale_index(struct mma8452_data *data,
 		ARRAY_SIZE(mma8452_scales), val, val2);
 }
 
+static int mma8452_get_hp_filter_index(struct mma8452_data *data,
+	int val, int val2)
+{
+	int i = mma8452_get_odr_index(data);
+
+	return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[i],
+		ARRAY_SIZE(mma8452_scales[0]), val, val2);
+}
+
 static int mma8452_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
@@ -232,6 +268,16 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
 			return ret;
 		*val = sign_extend32(ret, 7);
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+		ret = i2c_smbus_read_byte_data(data->client,
+						MMA8452_HP_FILTER_CUTOFF);
+		if (ret < 0)
+			return ret;
+		i = mma8452_get_odr_index(data);
+		ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
+		*val = mma8452_hp_filter_cutoff[i][ret][0];
+		*val2 = mma8452_hp_filter_cutoff[i][ret][1];
+		return IIO_VAL_INT_PLUS_MICRO;
 	}
 	return -EINVAL;
 }
@@ -278,7 +324,7 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
 			     int val, int val2, long mask)
 {
 	struct mma8452_data *data = iio_priv(indio_dev);
-	int i;
+	int i, reg;
 
 	if (iio_buffer_enabled(indio_dev))
 		return -EBUSY;
@@ -306,6 +352,19 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 		return mma8452_change_config(data, MMA8452_OFF_X +
 			chan->scan_index, val);
+	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+		i = mma8452_get_hp_filter_index(data, val, val2);
+		if (i < 0)
+			return -EINVAL;
+
+		reg = i2c_smbus_read_byte_data(data->client,
+						MMA8452_HP_FILTER_CUTOFF);
+		if (reg < 0)
+			return reg;
+		reg &= ~MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
+		reg |= i;
+		return mma8452_change_config(data,
+				MMA8452_HP_FILTER_CUTOFF, reg);
 	default:
 		return -EINVAL;
 	}
@@ -552,7 +611,8 @@ static struct attribute_group mma8452_event_attribute_group = {
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
 		BIT(IIO_CHAN_INFO_CALIBBIAS), \
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
-		BIT(IIO_CHAN_INFO_SCALE), \
+		BIT(IIO_CHAN_INFO_SCALE) | \
+		BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
 	.scan_index = idx, \
 	.scan_type = { \
 		.sign = 's', \
@@ -575,6 +635,7 @@ static const struct iio_chan_spec mma8452_channels[] = {
 static struct attribute *mma8452_attributes[] = {
 	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_accel_filter_high_pass_3db_frequency_available.dev_attr.attr,
 	NULL
 };