[PATCH V2 7/8] iio: mma8452: add an attribute to enable the highpass filter

[Martin Fuzzey <mfuzzey@parkeon.com>]

The hardware contains a single configurable highpass filter which
is normally used for transient detection (event).

However it is also possible to enable this filter for normal channel
reading. Add a new attribute in_accel_high_pass_filter_en to do this.

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
---
 drivers/iio/accel/mma8452.c |  115 +++++++++++++++++++++++++++++--------------
 1 file changed, 78 insertions(+), 37 deletions(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index eb68f9a..62589f9 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -62,6 +62,7 @@
 #define MMA8452_DATA_CFG_FS_2G 0
 #define MMA8452_DATA_CFG_FS_4G 1
 #define MMA8452_DATA_CFG_FS_8G 2
+#define MMA8452_DATA_CFG_HPF_MASK BIT(4)
 
 #define MMA8452_INT_DRDY	BIT(0)
 #define MMA8452_INT_FF_MT	BIT(2)
@@ -106,6 +107,43 @@ static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
 		MMA8452_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
 }
 
+static int mma8452_standby(struct mma8452_data *data)
+{
+	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
+		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
+}
+
+static int mma8452_active(struct mma8452_data *data)
+{
+	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
+		data->ctrl_reg1);
+}
+
+static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
+{
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	/* config can only be changed when in standby */
+	ret = mma8452_standby(data);
+	if (ret < 0)
+		goto fail;
+
+	ret = i2c_smbus_write_byte_data(data->client, reg, val);
+	if (ret < 0)
+		goto fail;
+
+	ret = mma8452_active(data);
+	if (ret < 0)
+		goto fail;
+
+	ret = 0;
+fail:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
 static ssize_t mma8452_show_int_plus_micros(char *buf,
 	const int (*vals)[2], int n)
 {
@@ -201,11 +239,50 @@ static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
 		ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));
 }
 
+static ssize_t mma8452_show_hp_cutoff_en(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);
+
+	return sprintf(buf, "%d\n",
+		data->data_cfg & MMA8452_DATA_CFG_HPF_MASK ? 1 : 0);
+}
+
+static ssize_t mma8452_store_hp_cutoff_en(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct mma8452_data *data = iio_priv(indio_dev);
+	bool state;
+	int ret;
+
+	ret = strtobool(buf, &state);
+	if (ret < 0)
+		return ret;
+
+	if (state)
+		data->data_cfg |= MMA8452_DATA_CFG_HPF_MASK;
+	else
+		data->data_cfg &= ~MMA8452_DATA_CFG_HPF_MASK;
+
+	ret = mma8452_change_config(data, MMA8452_DATA_CFG, data->data_cfg);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
 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 IIO_DEVICE_ATTR(in_accel_filter_high_pass_en,
+			 S_IRUGO | S_IWUSR,
+			 mma8452_show_hp_cutoff_en,
+			 mma8452_store_hp_cutoff_en, 0);
 
 static int mma8452_get_samp_freq_index(struct mma8452_data *data,
 	int val, int val2)
@@ -282,43 +359,6 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
-static int mma8452_standby(struct mma8452_data *data)
-{
-	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
-		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
-}
-
-static int mma8452_active(struct mma8452_data *data)
-{
-	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
-		data->ctrl_reg1);
-}
-
-static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
-{
-	int ret;
-
-	mutex_lock(&data->lock);
-
-	/* config can only be changed when in standby */
-	ret = mma8452_standby(data);
-	if (ret < 0)
-		goto fail;
-
-	ret = i2c_smbus_write_byte_data(data->client, reg, val);
-	if (ret < 0)
-		goto fail;
-
-	ret = mma8452_active(data);
-	if (ret < 0)
-		goto fail;
-
-	ret = 0;
-fail:
-	mutex_unlock(&data->lock);
-	return ret;
-}
-
 static int mma8452_write_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
@@ -636,6 +676,7 @@ 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,
+	&iio_dev_attr_in_accel_filter_high_pass_en.dev_attr.attr,
 	NULL
 };