linux-kernel - [PATCH] regmap: sdw: check for invalid multi-register writes config

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Date:   Tue, 23 May 2023 16:47:47 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     broonie@...nel.org
Cc:     gregkh@...uxfoundation.org, rafael@...nel.org,
        ckeepax@...nsource.cirrus.com, tanureal@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH] regmap: sdw: check for invalid multi-register writes config

SoundWire code as it is only supports Bulk register writes and
it does not support multi-register writes.

Any drivers that set can_multi_write and use regmap_multi_reg_write() will
easily endup with programming the hardware incorrectly without any errors.

So, add this check in bus code to be able to validate the drivers config.

Fixes: 522272047dc6 ("regmap: sdw: Remove 8-bit value size restriction")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/base/regmap/regmap-sdw.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/regmap/regmap-sdw.c b/drivers/base/regmap/regmap-sdw.c
index 09899ae99fc1..159c0b740b00 100644
--- a/drivers/base/regmap/regmap-sdw.c
+++ b/drivers/base/regmap/regmap-sdw.c
@@ -59,6 +59,10 @@ static int regmap_sdw_config_check(const struct regmap_config *config)
 	if (config->pad_bits != 0)
 		return -ENOTSUPP;
 
+	/* Only bulk writes are supported not multi-register writes */
+	if (config->can_multi_write)
+		return -ENOTSUPP;
+
 	return 0;
 }
 
-- 
2.21.0