[PATCH 4.9 23/87] iio: magnetometer: mag3110: claim direct mode during raw writes

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alison Schofield <amsfiel...@gmail.com>


[ Upstream commit 80dea21f95a4672cce545f48dc2ca500b69a2584 ]

Driver was checking for direct mode but not locking it.  Use
claim/release helper functions to guarantee the device stays
in direct mode during raw writes.

Signed-off-by: Alison Schofield <amsfiel...@gmail.com>
Acked-by: Peter Meerwald-Stadler <pme...@pmeerw.net>
Signed-off-by: Jonathan Cameron <ji...@kernel.org>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/iio/magnetometer/mag3110.c |   30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

--- a/drivers/iio/magnetometer/mag3110.c
+++ b/drivers/iio/magnetometer/mag3110.c
@@ -222,29 +222,39 @@ static int mag3110_write_raw(struct iio_
                             int val, int val2, long mask)
 {
        struct mag3110_data *data = iio_priv(indio_dev);
-       int rate;
+       int rate, ret;
 
-       if (iio_buffer_enabled(indio_dev))
-               return -EBUSY;
+       ret = iio_device_claim_direct_mode(indio_dev);
+       if (ret)
+               return ret;
 
        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                rate = mag3110_get_samp_freq_index(data, val, val2);
-               if (rate < 0)
-                       return -EINVAL;
+               if (rate < 0) {
+                       ret = -EINVAL;
+                       break;
+               }
 
                data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
                data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
-               return i2c_smbus_write_byte_data(data->client,
+               ret = i2c_smbus_write_byte_data(data->client,
                        MAG3110_CTRL_REG1, data->ctrl_reg1);
+               break;
        case IIO_CHAN_INFO_CALIBBIAS:
-               if (val < -10000 || val > 10000)
-                       return -EINVAL;
-               return i2c_smbus_write_word_swapped(data->client,
+               if (val < -10000 || val > 10000) {
+                       ret = -EINVAL;
+                       break;
+               }
+               ret = i2c_smbus_write_word_swapped(data->client,
                        MAG3110_OFF_X + 2 * chan->scan_index, val << 1);
+               break;
        default:
-               return -EINVAL;
+               ret = -EINVAL;
+               break;
        }
+       iio_device_release_direct_mode(indio_dev);
+       return ret;
 }
 
 static irqreturn_t mag3110_trigger_handler(int irq, void *p)