| From 78accaea117c1ae878774974fab91ac4a0b0e2b0 Mon Sep 17 00:00:00 2001 |
| From: Jeremy Fertic <jeremyfertic@gmail.com> |
| Date: Sat, 22 Dec 2018 21:57:43 -0700 |
| Subject: staging: iio: adt7316: fix the dac write calculation |
| |
| From: Jeremy Fertic <jeremyfertic@gmail.com> |
| |
| commit 78accaea117c1ae878774974fab91ac4a0b0e2b0 upstream. |
| |
| The lsb calculation is not masking the correct bits from the user input. |
| Subtract 1 from (1 << offset) to correctly set up the mask to be applied |
| to user input. |
| |
| The lsb register stores its value starting at the bit 7 position. |
| adt7316_store_DAC() currently assumes the value is at the other end of the |
| register. Shift the lsb value before storing it in a new variable lsb_reg, |
| and write this variable to the lsb register. |
| |
| Fixes: 35f6b6b86ede ("staging: iio: new ADT7316/7/8 and ADT7516/7/9 driver") |
| Signed-off-by: Jeremy Fertic <jeremyfertic@gmail.com> |
| Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/staging/iio/addac/adt7316.c | 10 +++++++--- |
| 1 file changed, 7 insertions(+), 3 deletions(-) |
| |
| --- a/drivers/staging/iio/addac/adt7316.c |
| +++ b/drivers/staging/iio/addac/adt7316.c |
| @@ -1442,7 +1442,7 @@ static ssize_t adt7316_show_DAC(struct a |
| static ssize_t adt7316_store_DAC(struct adt7316_chip_info *chip, |
| int channel, const char *buf, size_t len) |
| { |
| - u8 msb, lsb, offset; |
| + u8 msb, lsb, lsb_reg, offset; |
| u16 data; |
| int ret; |
| |
| @@ -1460,9 +1460,13 @@ static ssize_t adt7316_store_DAC(struct |
| return -EINVAL; |
| |
| if (chip->dac_bits > 8) { |
| - lsb = data & (1 << offset); |
| + lsb = data & ((1 << offset) - 1); |
| + if (chip->dac_bits == 12) |
| + lsb_reg = lsb << ADT7316_DA_12_BIT_LSB_SHIFT; |
| + else |
| + lsb_reg = lsb << ADT7316_DA_10_BIT_LSB_SHIFT; |
| ret = chip->bus.write(chip->bus.client, |
| - ADT7316_DA_DATA_BASE + channel * 2, lsb); |
| + ADT7316_DA_DATA_BASE + channel * 2, lsb_reg); |
| if (ret) |
| return -EIO; |
| } |