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iio: dac: ad5593r: Fix i2c read protocol requirements

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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: 56ca9db862 ("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>
This commit is contained in:
Michael Hennerich 2022-09-13 09:34:12 +02:00 committed by Jonathan Cameron
parent d9d0c0725a
commit 558a25f903
1 changed files with 27 additions and 19 deletions
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46
drivers/iio/dac/ad5593r.c
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@ -13,6 +13,8 @@
#include <linux/module.h> #include <linux/module.h>
#include <linux/mod_devicetable.h> #include <linux/mod_devicetable.h>
#include <asm/unaligned.h>
#define AD5593R_MODE_CONF (0 << 4) #define AD5593R_MODE_CONF (0 << 4)
#define AD5593R_MODE_DAC_WRITE (1 << 4) #define AD5593R_MODE_DAC_WRITE (1 << 4)
#define AD5593R_MODE_ADC_READBACK (4 << 4) #define AD5593R_MODE_ADC_READBACK (4 << 4)
@ -20,6 +22,24 @@
#define AD5593R_MODE_GPIO_READBACK (6 << 4) #define AD5593R_MODE_GPIO_READBACK (6 << 4)
#define AD5593R_MODE_REG_READBACK (7 << 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) static int ad5593r_write_dac(struct ad5592r_state *st, unsigned chan, u16 value)
{ {
struct i2c_client *i2c = to_i2c_client(st->dev); 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) if (val < 0)
return (int) val; return (int) val;
val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_ADC_READBACK); return ad5593r_read_word(i2c, AD5593R_MODE_ADC_READBACK, value);
if (val < 0)
return (int) val;
*value = (u16) val;
return 0;
} }
static int ad5593r_reg_write(struct ad5592r_state *st, u8 reg, u16 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) static int ad5593r_reg_read(struct ad5592r_state *st, u8 reg, u16 *value)
{ {
struct i2c_client *i2c = to_i2c_client(st->dev); struct i2c_client *i2c = to_i2c_client(st->dev);
s32 val;
val = i2c_smbus_read_word_swapped(i2c, AD5593R_MODE_REG_READBACK | reg); return ad5593r_read_word(i2c, AD5593R_MODE_REG_READBACK | reg, value);
if (val < 0)
return (int) val;
*value = (u16) val;
return 0;
} }
static int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value) static int ad5593r_gpio_read(struct ad5592r_state *st, u8 *value)
{ {
struct i2c_client *i2c = to_i2c_client(st->dev); 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); ret = ad5593r_read_word(i2c, AD5593R_MODE_GPIO_READBACK, &val);
if (val < 0) if (ret)
return (int) val; return ret;
*value = (u8) val; *value = (u8) val;