linux-kernel - [PATCH AUTOSEL 6.14 493/642] iio: adc: ad7606: protect register access

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Message-Id: <20250505221419.2672473-493-sashal@kernel.org>
Date: Mon,  5 May 2025 18:11:49 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Angelo Dureghello <adureghello@...libre.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Sasha Levin <sashal@...nel.org>,
	lars@...afoo.de,
	Michael.Hennerich@...log.com,
	jic23@...nel.org,
	linux-iio@...r.kernel.org
Subject: [PATCH AUTOSEL 6.14 493/642] iio: adc: ad7606: protect register access

From: Angelo Dureghello <adureghello@...libre.com>

[ Upstream commit 0f65f59e632d942cccffd12c36036c24eb7037eb ]

Protect register (and bus) access from concurrent
read / write. Needed in the backend operating mode.

Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
Link: https://patch.msgid.link/20250210-wip-bl-ad7606_add_backend_sw_mode-v4-7-160df18b1da7@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iio/adc/ad7606.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index d39354afd5394..2b0725449a6ab 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -852,7 +852,12 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
 		}
 		val = (val * MICRO) + val2;
 		i = find_closest(val, scale_avail_uv, cs->num_scales);
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret < 0)
+			return ret;
 		ret = st->write_scale(indio_dev, ch, i + cs->reg_offset);
+		iio_device_release_direct_mode(indio_dev);
 		if (ret < 0)
 			return ret;
 		cs->range = i;
@@ -863,7 +868,12 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 		i = find_closest(val, st->oversampling_avail,
 				 st->num_os_ratios);
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret < 0)
+			return ret;
 		ret = st->write_os(indio_dev, i);
+		iio_device_release_direct_mode(indio_dev);
 		if (ret < 0)
 			return ret;
 		st->oversampling = st->oversampling_avail[i];
-- 
2.39.5