linux-kernel - [PATCH v3 1/6] iio: adc: ad4080: fix chip identification

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Message-ID: <20251007111525.25711-2-antoniu.miclaus@analog.com>
Date: Tue, 7 Oct 2025 11:15:20 +0000
From: Antoniu Miclaus <antoniu.miclaus@...log.com>
To: <jic23@...nel.org>, <robh@...nel.org>, <conor+dt@...nel.org>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
CC: Antoniu Miclaus <antoniu.miclaus@...log.com>
Subject: [PATCH v3 1/6] iio: adc: ad4080: fix chip identification

Fix AD4080 chip identification by using the correct 16-bit product ID
(0x0050) instead of GENMASK(2, 0). Update the chip reading logic to
use regmap_bulk_read to read both PRODUCT_ID_L and PRODUCT_ID_H
registers and combine them into a 16-bit value.

The original implementation was incorrectly reading only 3 bits,
which would not correctly identify the AD4080 chip.

Fixes: 6b31ba1811b6 ("iio: adc: ad4080: add driver support")
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
---
changes in v3:
 - use le16_to_cpu to convert the read little-endian value to CPU endianness
 drivers/iio/adc/ad4080.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ad4080.c b/drivers/iio/adc/ad4080.c
index 6e61787ed321..ae5a975a47a5 100644
--- a/drivers/iio/adc/ad4080.c
+++ b/drivers/iio/adc/ad4080.c
@@ -125,7 +125,7 @@
 
 /* Miscellaneous Definitions */
 #define AD4080_SPI_READ						BIT(7)
-#define AD4080_CHIP_ID						GENMASK(2, 0)
+#define AD4080_CHIP_ID						0x0050
 
 #define AD4080_LVDS_CNV_CLK_CNT_MAX				7
 
@@ -445,7 +445,8 @@ static int ad4080_setup(struct iio_dev *indio_dev)
 {
 	struct ad4080_state *st = iio_priv(indio_dev);
 	struct device *dev = regmap_get_device(st->regmap);
-	unsigned int id;
+	__le16 id_le;
+	u16 id;
 	int ret;
 
 	ret = regmap_write(st->regmap, AD4080_REG_INTERFACE_CONFIG_A,
@@ -458,10 +459,11 @@ static int ad4080_setup(struct iio_dev *indio_dev)
 	if (ret)
 		return ret;
 
-	ret = regmap_read(st->regmap, AD4080_REG_CHIP_TYPE, &id);
+	ret = regmap_bulk_read(st->regmap, AD4080_REG_PRODUCT_ID_L, &id_le, 2);
 	if (ret)
 		return ret;
 
+	id = le16_to_cpu(id_le);
 	if (id != AD4080_CHIP_ID)
 		dev_info(dev, "Unrecognized CHIP_ID 0x%X\n", id);
 
-- 
2.43.0