This is a note to let you know that I've just added the patch titled
iio: dac: ad5593r: Fix i2c read protocol requirements
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iio-dac-ad5593r-fix-i2c-read-protocol-requirements.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 558a25f903b4af6361b7fbeea08a6446a0745653 Mon Sep 17 00:00:00 2001
From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
Date: Tue, 13 Sep 2022 09:34:12 +0200
Subject: iio: dac: ad5593r: Fix i2c read protocol requirements
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From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
commit 558a25f903b4af6361b7fbeea08a6446a0745653 upstream.
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@xxxxxxxxxx>
Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220913073413.140475-2-nuno.sa@xxxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iio/dac/ad5593r.c | 46 +++++++++++++++++++++++++++-------------------
1 file changed, 27 insertions(+), 19 deletions(-)
--- a/drivers/iio/dac/ad5593r.c
+++ b/drivers/iio/dac/ad5593r.c
@@ -14,6 +14,8 @@
#include <linux/module.h>
#include <linux/of.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)
@@ -21,6 +23,24 @@
#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);
@@ -39,13 +59,7 @@ static int ad5593r_read_adc(struct ad559
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)
@@ -59,25 +73,19 @@ static int ad5593r_reg_write(struct ad55
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;
Patches currently in stable-queue which might be from michael.hennerich@xxxxxxxxxx are
queue-4.9/iio-dac-ad5593r-fix-i2c-read-protocol-requirements.patch
