Re: [PATCH v8 3/8] iio: dac: ad5686: refactor command/data macros
From: Jonathan Cameron
Date: Sat Jul 18 2026 - 19:59:35 EST
On Thu, 16 Jul 2026 13:14:19 +0100
Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@xxxxxxxxxx> wrote:
> From: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
>
> Replace usage of bit shifting macros for FIELD_PREP(), which would not
> ignore bit masking when preparing SPI/I2C commands. This change is a code
> hardening measure to be paired with the upcoming triggered buffer support.
> For the AD5310 regmap case, 16-bit data coming from the buffer may overlap
> with command bits if the data field is unmasked.
>
> *_REF_BIT_MSK and *_PD_MSK bit position macros are renamed (with a DATA
> prefix) so to indicate that they are relative to the DATA field.
>
> Reported-by: sashiko-bot@xxxxxxxxxx
> Closes: https://lore.kernel.org/all/20260628143026.EC6CA1F000E9@xxxxxxxxxxxxxxx/
> Reviewed-by: David Lechner <dlechner@xxxxxxxxxxxx>
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
Some fuzz when applying this due at least partly to crossing with various
header cleanup related series. Please check I didn't mess it up!
Thanks,
Jonathan
> ---
> drivers/iio/dac/ad5686-spi.c | 21 +++++++++++----------
> drivers/iio/dac/ad5686.c | 10 +++++-----
> drivers/iio/dac/ad5686.h | 22 ++++++++++++----------
> drivers/iio/dac/ad5696-i2c.c | 11 ++++++-----
> 4 files changed, 34 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/iio/dac/ad5686-spi.c b/drivers/iio/dac/ad5686-spi.c
> index 6b6ef1d7071f..d3b64b4361d5 100644
> --- a/drivers/iio/dac/ad5686-spi.c
> +++ b/drivers/iio/dac/ad5686-spi.c
> @@ -9,6 +9,7 @@
> */
>
> #include <linux/array_size.h>
> +#include <linux/bitfield.h>
> #include <linux/errno.h>
> #include <linux/mod_devicetable.h>
> #include <linux/module.h>
> @@ -26,21 +27,21 @@ static int ad5686_spi_write(struct ad5686_state *st,
>
> switch (st->chip_info->regmap_type) {
> case AD5310_REGMAP:
> - st->data[0].d16 = cpu_to_be16(AD5310_CMD(cmd) |
> - val);
> + st->data[0].d16 = cpu_to_be16(FIELD_PREP(AD5310_CMD_MSK, cmd) |
> + FIELD_PREP(AD5310_DATA_MSK, val));
> buf = &st->data[0].d8[0];
> tx_len = 2;
> break;
> case AD5683_REGMAP:
> - st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
> - AD5683_DATA(val));
> + st->data[0].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, cmd) |
> + FIELD_PREP(AD5683_DATA_MSK, val));
> buf = &st->data[0].d8[1];
> tx_len = 3;
> break;
> case AD5686_REGMAP:
> - st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
> - AD5686_ADDR(addr) |
> - val);
> + st->data[0].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, cmd) |
> + FIELD_PREP(AD5686_ADDR_MSK, addr) |
> + FIELD_PREP(AD5686_DATA_MSK, val));
> buf = &st->data[0].d8[1];
> tx_len = 3;
> break;
> @@ -81,9 +82,9 @@ static int ad5686_spi_read(struct ad5686_state *st, u8 addr)
> return -EINVAL;
> }
>
> - st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
> - AD5686_ADDR(addr));
> - st->data[1].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP));
> + st->data[0].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, cmd) |
> + FIELD_PREP(AD5686_ADDR_MSK, addr));
> + st->data[1].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, AD5686_CMD_NOOP));
>
> ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
> if (ret < 0)
> diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
> index d34250647aa4..c285aeed44d1 100644
> --- a/drivers/iio/dac/ad5686.c
> +++ b/drivers/iio/dac/ad5686.c
> @@ -35,8 +35,8 @@ static int ad5310_control_sync(struct ad5686_state *st)
> unsigned int pd_val = st->pwr_down_mask & st->pwr_down_mode;
>
> return ad5686_write(st, AD5686_CMD_CONTROL_REG, 0,
> - FIELD_PREP(AD5310_PD_MSK, pd_val & AD5686_PD_MSK) |
> - FIELD_PREP(AD5310_REF_BIT_MSK, st->use_internal_vref ? 0 : 1));
> + FIELD_PREP(AD5310_DATA_PD_MSK, pd_val & AD5686_PD_MSK) |
> + FIELD_PREP(AD5310_DATA_REF_MSK, st->use_internal_vref ? 0 : 1));
> }
>
> static int ad5683_control_sync(struct ad5686_state *st)
> @@ -44,8 +44,8 @@ static int ad5683_control_sync(struct ad5686_state *st)
> unsigned int pd_val = st->pwr_down_mask & st->pwr_down_mode;
>
> return ad5686_write(st, AD5686_CMD_CONTROL_REG, 0,
> - FIELD_PREP(AD5683_PD_MSK, pd_val & AD5686_PD_MSK) |
> - FIELD_PREP(AD5683_REF_BIT_MSK, st->use_internal_vref ? 0 : 1));
> + FIELD_PREP(AD5683_DATA_PD_MSK, pd_val & AD5686_PD_MSK) |
> + FIELD_PREP(AD5683_DATA_REF_MSK, st->use_internal_vref ? 0 : 1));
> }
>
> static inline unsigned int ad5686_pd_mask_shift(const struct iio_chan_spec *chan)
> @@ -565,7 +565,7 @@ int ad5686_probe(struct device *dev,
> break;
> case AD5686_REGMAP:
> ret = ad5686_write(st, AD5686_CMD_INTERNAL_REFER_SETUP, 0,
> - st->use_internal_vref ? 0 : AD5686_REF_BIT_MSK);
> + st->use_internal_vref ? 0 : AD5686_DATA_REF_MSK);
> if (ret)
> return ret;
> break;
> diff --git a/drivers/iio/dac/ad5686.h b/drivers/iio/dac/ad5686.h
> index c424720f8f72..32cb3931413c 100644
> --- a/drivers/iio/dac/ad5686.h
> +++ b/drivers/iio/dac/ad5686.h
> @@ -14,12 +14,14 @@
>
> #include <linux/iio/iio.h>
>
> -#define AD5310_CMD(x) ((x) << 12)
> +#define AD5310_CMD_MSK GENMASK(15, 12)
> +#define AD5310_DATA_MSK GENMASK(11, 0)
>
> -#define AD5683_DATA(x) ((x) << 4)
> +#define AD5683_DATA_MSK GENMASK(19, 4)
>
> -#define AD5686_ADDR(x) ((x) << 16)
> -#define AD5686_CMD(x) ((x) << 20)
> +#define AD5686_CMD_MSK GENMASK(23, 20)
> +#define AD5686_ADDR_MSK GENMASK(19, 16)
> +#define AD5686_DATA_MSK GENMASK(15, 0)
>
> #define AD5686_ADDR_DAC(chan) (0x1 << (chan))
> #define AD5686_ADDR_ALL_DAC 0xF
> @@ -38,15 +40,15 @@
> #define AD5686_CMD_CONTROL_REG 0x4
> #define AD5686_CMD_READBACK_ENABLE_V2 0x5
>
> -#define AD5310_REF_BIT_MSK BIT(8)
> -#define AD5310_PD_MSK GENMASK(10, 9)
> +#define AD5310_DATA_REF_MSK BIT(8)
> +#define AD5310_DATA_PD_MSK GENMASK(10, 9)
>
> -#define AD5683_REF_BIT_MSK BIT(12)
> -#define AD5683_PD_MSK GENMASK(14, 13)
> +#define AD5683_DATA_REF_MSK BIT(12) /* DB16 */
> +#define AD5683_DATA_PD_MSK GENMASK(14, 13) /* DB18:DB17 */
> +
> +#define AD5686_DATA_REF_MSK BIT(0)
>
> -#define AD5686_REF_BIT_MSK BIT(0)
> #define AD5686_PD_MSK GENMASK(1, 0)
> -
> #define AD5686_PD_MODE_1K_TO_GND 0x1
> #define AD5686_PD_MODE_100K_TO_GND 0x2
> #define AD5686_PD_MODE_THREE_STATE 0x3
> diff --git a/drivers/iio/dac/ad5696-i2c.c b/drivers/iio/dac/ad5696-i2c.c
> index 551b200bfe14..2c95d394a1c0 100644
> --- a/drivers/iio/dac/ad5696-i2c.c
> +++ b/drivers/iio/dac/ad5696-i2c.c
> @@ -8,6 +8,7 @@
> */
>
> #include <linux/array_size.h>
> +#include <linux/bitfield.h>
> #include <linux/errno.h>
> #include <linux/i2c.h>
> #include <linux/mod_devicetable.h>
> @@ -36,9 +37,8 @@ static int ad5686_i2c_read(struct ad5686_state *st, u8 addr)
> };
> int ret;
>
> - st->data[0].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP) |
> - AD5686_ADDR(addr) |
> - 0x00);
> + st->data[0].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, AD5686_CMD_NOOP) |
> + FIELD_PREP(AD5686_ADDR_MSK, addr));
>
> ret = i2c_transfer(i2c->adapter, msg, ARRAY_SIZE(msg));
> if (ret < 0)
> @@ -55,8 +55,9 @@ static int ad5686_i2c_write(struct ad5686_state *st,
> struct i2c_client *i2c = to_i2c_client(st->dev);
> int ret;
>
> - st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) | AD5686_ADDR(addr)
> - | val);
> + st->data[0].d32 = cpu_to_be32(FIELD_PREP(AD5686_CMD_MSK, cmd) |
> + FIELD_PREP(AD5686_ADDR_MSK, addr) |
> + FIELD_PREP(AD5686_DATA_MSK, val));
>
> ret = i2c_master_send(i2c, &st->data[0].d8[1], 3);
> if (ret < 0)
>