Commit 558a25f9 authored by Michael Hennerich's avatar Michael Hennerich Committed by Jonathan Cameron
Browse files

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: 56ca9db8 ("iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs")
Signed-off-by: default avatarMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: default avatarNuno 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: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent d9d0c072

drivers/iio/dac/ad5593r.c

+27 −19
Original line number Diff line number Diff line
@@ -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;