diff options
| author | Michael Hennerich <michael.hennerich@analog.com> | 2022-09-13 10:34:12 +0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-09-21 20:42:53 +0300 |
| commit | 558a25f903b4af6361b7fbeea08a6446a0745653 (patch) | |
| tree | 8ab524558c08a3604ba5e9d511f0f5f4660c6435 /drivers/iio/dac | |
| parent | d9d0c0725ae2798bd51f38ae26c2477f6eed40b3 (diff) | |
| download | linux-558a25f903b4af6361b7fbeea08a6446a0745653.tar.xz | |
iio: dac: ad5593r: Fix i2c read protocol requirements
For reliable operation across the full range of supported
interface rates, the AD5593R needs a STOP condition between
address write, and data read (like show in the datasheet Figure 40)
so in turn i2c_smbus_read_word_swapped cannot be used.
While at it, a simple helper was added to make the code simpler.
Fixes: 56ca9db862bf ("iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs")
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220913073413.140475-2-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio/dac')
| -rw-r--r-- | drivers/iio/dac/ad5593r.c | 46 |
1 files changed, 27 insertions, 19 deletions
diff --git a/drivers/iio/dac/ad5593r.c b/drivers/iio/dac/ad5593r.c index 34e1319a9712..356dc0bab115 100644 --- a/drivers/iio/dac/ad5593r.c +++ b/drivers/iio/dac/ad5593r.c @@ -13,6 +13,8 @@ #include <linux/module.h> #include <linux/mod_devicetable.h> +#include <asm/unaligned.h> + #define AD5593R_MODE_CONF (0 << 4) #define AD5593R_MODE_DAC_WRITE (1 << 4) #define AD5593R_MODE_ADC_READBACK (4 << 4) @@ -20,6 +22,24 @@ #define AD5593R_MODE_GPIO_READBACK (6 << 4) #define AD5593R_MODE_REG_READBACK (7 << 4) +static int ad5593r_read_word(struct i2c_client *i2c, u8 reg, u16 *value) +{ + int ret; + u8 buf[2]; + + ret = i2c_smbus_write_byte(i2c, reg); + if (ret < 0) + return ret; + + ret = i2c_master_recv(i2c, buf, sizeof(buf)); + if (ret < 0) + return ret; + + *value = get_unaligned_be16(buf); + + return 0; +} + static int ad5593r_write_dac(struct ad5592r_state *st, unsigned chan, u16 value) { struct i2c_client *i2c = to_i2c_client(st->dev); @@ -38,13 +58,7 @@ static int ad5593r_read_adc(struct ad5592r_state *st, unsigned chan, u16 *value) if (val < 0) return (int) val; - val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_ADC_READBACK); - if (val < 0) - return (int) val; - - *value = (u16) val; - - return 0; + return ad5593r_read_word(i2c, AD5593R_MODE_ADC_READBACK, value); } static int ad5593r_reg_write(struct ad5592r_state *st, u8 reg, u16 value) @@ -58,25 +72,19 @@ static int ad5593r_reg_write(struct ad5592r_state *st, u8 reg, u16 value) static int ad5593r_reg_read(struct ad5592r_state *st, u8 reg, u16 *value) { struct i2c_client *i2c = to_i2c_client(st->dev); - s32 val; - - val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_REG_READBACK | reg); - if (val < 0) - return (int) val; - *value = (u16) val; - - return 0; + return ad5593r_read_word(i2c, AD5593R_MODE_REG_READBACK | reg, value); } static int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value) { struct i2c_client *i2c = to_i2c_client(st->dev); - s32 val; + u16 val; + int ret; - val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_GPIO_READBACK); - if (val < 0) - return (int) val; + ret = ad5593r_read_word(i2c, AD5593R_MODE_GPIO_READBACK, &val); + if (ret) + return ret; *value = (u8) val; |