1 files changed, 58 insertions, 4 deletions

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 5b80657..877ce29 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -32,6 +32,9 @@
 #define MMA8452_OFF_Z 0x31
 #define MMA8452_CTRL_REG1 0x2a
 #define MMA8452_CTRL_REG2 0x2b
+#define MMA8452_CTRL_REG2_RST		BIT(6)
+
+#define MMA8452_MAX_REG 0x31
 
 #define MMA8452_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))
 
@@ -291,6 +294,28 @@ done:
 	return IRQ_HANDLED;
 }
 
+static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
+				  unsigned reg, unsigned writeval,
+				  unsigned *readval)
+{
+	int ret;
+	struct mma8452_data *data = iio_priv(indio_dev);
+
+	if (reg > MMA8452_MAX_REG)
+		return -EINVAL;
+
+	if (!readval)
+		return mma8452_change_config(data, reg, writeval);
+
+	ret = i2c_smbus_read_byte_data(data->client, reg);
+	if (ret < 0)
+		return ret;
+
+	*readval = ret;
+
+	return 0;
+}
+
 #define MMA8452_CHANNEL(axis, idx) { \
 	.type = IIO_ACCEL, \
 	.modified = 1, \
@@ -330,11 +355,36 @@ static const struct iio_info mma8452_info = {
 	.attrs = &mma8452_group,
 	.read_raw = &mma8452_read_raw,
 	.write_raw = &mma8452_write_raw,
+	.debugfs_reg_access = &mma8452_reg_access_dbg,
 	.driver_module = THIS_MODULE,
 };
 
 static const unsigned long mma8452_scan_masks[] = {0x7, 0};
 
+static int mma8452_reset(struct i2c_client *client)
+{
+	int i;
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client,	MMA8452_CTRL_REG2,
+					MMA8452_CTRL_REG2_RST);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < 10; i++) {
+		usleep_range(100, 200);
+		ret = i2c_smbus_read_byte_data(client, MMA8452_CTRL_REG2);
+		if (ret == -EIO)
+			continue; /* I2C comm reset */
+		if (ret < 0)
+			return ret;
+		if (!(ret & MMA8452_CTRL_REG2_RST))
+			return 0;
+	}
+
+	return -ETIMEDOUT;
+}
+
 static int mma8452_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
@@ -365,10 +415,7 @@ static int mma8452_probe(struct i2c_client *client,
 	indio_dev->num_channels = ARRAY_SIZE(mma8452_channels);
 	indio_dev->available_scan_masks = mma8452_scan_masks;
 
-	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
-		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
-	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
-		data->ctrl_reg1);
+	ret = mma8452_reset(client);
 	if (ret < 0)
 		return ret;
 
@@ -378,6 +425,13 @@ static int mma8452_probe(struct i2c_client *client,
 	if (ret < 0)
 		return ret;
 
+	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
+		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
+	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
+					data->ctrl_reg1);
+	if (ret < 0)
+		return ret;
+
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		mma8452_trigger_handler, NULL);
 	if (ret < 0)