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authorMichael Hennerich <michael.hennerich@analog.com>2022-09-13 10:34:12 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2022-09-21 20:42:53 +0300
commit558a25f903b4af6361b7fbeea08a6446a0745653 (patch)
tree8ab524558c08a3604ba5e9d511f0f5f4660c6435 /drivers/iio/dac
parentd9d0c0725ae2798bd51f38ae26c2477f6eed40b3 (diff)
downloadlinux-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.c46
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;