[PATCH v3 1/4] iio: adc: ad9467: include two's complement in default mode

Tomas Melin
2026-01-14T10:46:15Z

All supported drivers currently implicitly use two's complement mode.
Make this clear by declaring two's complement in the default
output mode. Calibration mode uses offset binary, so change the output
mode only when running the calibration or other test mode.

Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
---
drivers/iio/adc/ad9467.c | 33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index 59c3fa3bcc9b0b8b36b78c3b54fd7977cae23496..9cfe66425d4e91e215cccc40e24a92c5e99e9b87 100644
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -5,6 +5,7 @@
* Copyright 2012-2020 Analog Devices Inc.
*/

+#include <linux/bitfield.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
@@ -72,6 +73,7 @@
#define AN877_ADC_OUTPUT_MODE_OFFSET_BINARY 0x0
#define AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT 0x1
#define AN877_ADC_OUTPUT_MODE_GRAY_CODE 0x2
+#define AN877_ADC_OUTPUT_MODE_MASK GENMASK(1, 0)

/* AN877_ADC_REG_OUTPUT_PHASE */
#define AN877_ADC_OUTPUT_EVEN_ODD_MODE_EN 0x20
@@ -85,7 +87,7 @@
*/

#define CHIPID_AD9211 0x06
-#define AD9211_DEF_OUTPUT_MODE 0x00
+#define AD9211_DEF_OUTPUT_MODE 0x01
#define AD9211_REG_VREF_MASK GENMASK(4, 0)

/*
@@ -93,7 +95,7 @@
*/

#define CHIPID_AD9265 0x64
-#define AD9265_DEF_OUTPUT_MODE 0x40
+#define AD9265_DEF_OUTPUT_MODE 0x41
#define AD9265_REG_VREF_MASK 0xC0

/*
@@ -101,7 +103,7 @@
*/

#define CHIPID_AD9434 0x6A
-#define AD9434_DEF_OUTPUT_MODE 0x00
+#define AD9434_DEF_OUTPUT_MODE 0x01
#define AD9434_REG_VREF_MASK 0xC0

/*
@@ -109,7 +111,7 @@
*/

#define CHIPID_AD9467 0x50
-#define AD9467_DEF_OUTPUT_MODE 0x08
+#define AD9467_DEF_OUTPUT_MODE 0x09
#define AD9467_REG_VREF_MASK 0x0F

/*
@@ -117,6 +119,7 @@
*/

#define CHIPID_AD9643 0x82
+#define AD9643_DEF_OUTPUT_MODE 0x01
#define AD9643_REG_VREF_MASK 0x1F

/*
@@ -124,6 +127,7 @@
*/

#define CHIPID_AD9652 0xC1
+#define AD9652_DEF_OUTPUT_MODE 0x01
#define AD9652_REG_VREF_MASK 0xC0

/*
@@ -131,6 +135,7 @@
*/

#define CHIPID_AD9649 0x6F
+#define AD9649_DEF_OUTPUT_MODE 0x01
#define AD9649_TEST_POINTS 8

#define AD9647_MAX_TEST_POINTS 32
@@ -461,6 +466,7 @@ static const struct ad9467_chip_info ad9643_chip_tbl = {
.test_mask = BIT(AN877_ADC_TESTMODE_RAMP) |
GENMASK(AN877_ADC_TESTMODE_MIXED_BIT_FREQUENCY, AN877_ADC_TESTMODE_OFF),
.test_mask_len = AN877_ADC_TESTMODE_RAMP + 1,
+ .default_output_mode = AD9643_DEF_OUTPUT_MODE,
.vref_mask = AD9643_REG_VREF_MASK,
.has_dco = true,
.has_dco_invert = true,
@@ -479,6 +485,7 @@ static const struct ad9467_chip_info ad9649_chip_tbl = {
.test_mask = GENMASK(AN877_ADC_TESTMODE_MIXED_BIT_FREQUENCY,
AN877_ADC_TESTMODE_OFF),
.test_mask_len = AN877_ADC_TESTMODE_MIXED_BIT_FREQUENCY + 1,
+ .default_output_mode = AD9649_DEF_OUTPUT_MODE,
.has_dco = true,
.has_dco_invert = true,
.dco_en = AN877_ADC_DCO_DELAY_ENABLE,
@@ -496,6 +503,7 @@ static const struct ad9467_chip_info ad9652_chip_tbl = {
.test_mask = GENMASK(AN877_ADC_TESTMODE_ONE_ZERO_TOGGLE,
AN877_ADC_TESTMODE_OFF),
.test_mask_len = AN877_ADC_TESTMODE_ONE_ZERO_TOGGLE + 1,
+ .default_output_mode = AD9652_DEF_OUTPUT_MODE,
.vref_mask = AD9652_REG_VREF_MASK,
.has_dco = true,
};
@@ -671,10 +679,14 @@ static int ad9467_backend_testmode_off(struct ad9467_state *st,

static int ad9647_calibrate_prepare(struct ad9467_state *st)
{
+ unsigned int cmode;
unsigned int c;
int ret;

- ret = ad9467_outputmode_set(st, st->info->default_output_mode);
+ cmode = st->info->default_output_mode;
+ FIELD_MODIFY(AN877_ADC_OUTPUT_MODE_MASK, &cmode,
+ AN877_ADC_OUTPUT_MODE_OFFSET_BINARY);
+ ret = ad9467_outputmode_set(st, cmode);
if (ret)
return ret;

@@ -778,7 +790,7 @@ static int ad9647_calibrate_stop(struct ad9467_state *st)
return ret;
}

- mode = st->info->default_output_mode | AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
+ mode = st->info->default_output_mode;
return ad9467_outputmode_set(st, mode);
}

@@ -1174,12 +1186,17 @@ static ssize_t ad9467_chan_test_mode_write(struct file *file,
if (ret)
return ret;

- out_mode = st->info->default_output_mode | AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
+ out_mode = st->info->default_output_mode;
ret = ad9467_outputmode_set(st, out_mode);
if (ret)
return ret;
} else {
- ret = ad9467_outputmode_set(st, st->info->default_output_mode);
+ unsigned int cmode;
+
+ cmode = st->info->default_output_mode;
+ FIELD_MODIFY(AN877_ADC_OUTPUT_MODE_MASK, &cmode,
+ AN877_ADC_OUTPUT_MODE_OFFSET_BINARY);
+ ret = ad9467_outputmode_set(st, cmode);
if (ret)
return ret;

--
2.47.3