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Commit f16e8317 authored by Jeremy Fertic's avatar Jeremy Fertic Committed by Greg Kroah-Hartman
Browse files

staging: iio: adt7316: fix the dac write calculation 



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: 35f6b6b8 ("staging: iio: new ADT7316/7/8 and ADT7516/7/9 driver")
Signed-off-by: default avatarJeremy Fertic <jeremyfertic@gmail.com>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad774285

drivers/staging/iio/addac/adt7316.c

+7 −3
Original line number Original line Diff line number Diff line
@@ -1447,7 +1447,7 @@ static ssize_t adt7316_show_DAC(struct adt7316_chip_info *chip, 
static ssize_t adt7316_store_DAC(struct adt7316_chip_info *chip,

static ssize_t adt7316_store_DAC(struct adt7316_chip_info *chip,

		int channel, const char *buf, size_t len)

		int channel, const char *buf, size_t len)

{

{

	u8 msb, lsb, offset;

	u8 msb, lsb, lsb_reg, offset;

	u16 data;

	u16 data;

	int ret;

	int ret;
@@ -1465,9 +1465,13 @@ static ssize_t adt7316_store_DAC(struct adt7316_chip_info *chip, 
		return -EINVAL;

		return -EINVAL;





	if (chip->dac_bits > 8) {

	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,

		ret = chip->bus.write(chip->bus.client,

			ADT7316_DA_DATA_BASE + channel * 2, lsb);

			ADT7316_DA_DATA_BASE + channel * 2, lsb_reg);

		if (ret)

		if (ret)

			return -EIO;

			return -EIO;

	}

	}