linux-kernel - [PATCH AUTOSEL 5.10 5/9] spi: spi-imx: fix MX51_ECSPI

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Date:   Sat,  6 May 2023 20:35:41 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Kevin Groeneveld <kgroeneveld@...brook.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>, shawnguo@...nel.org,
        linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 5.10 5/9] spi: spi-imx: fix MX51_ECSPI_* macros when cs > 3

From: Kevin Groeneveld <kgroeneveld@...brook.com>

[ Upstream commit 87c614175bbf28d3fd076dc2d166bac759e41427 ]

When using gpio based chip select the cs value can go outside the range
0 – 3. The various MX51_ECSPI_* macros did not take this into consideration
resulting in possible corruption of the configuration.

For example for any cs value over 3 the SCLKPHA bits would not be set and
other values in the register possibly corrupted.

One way to fix this is to just mask the cs bits to 2 bits. This still
allows all 4 native chip selects to work as well as gpio chip selects
(which can use any of the 4 chip select configurations).

Signed-off-by: Kevin Groeneveld <kgroeneveld@...brook.com>
Link: https://lore.kernel.org/r/20230318222132.3373-1-kgroeneveld@lenbrook.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/spi/spi-imx.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 74b3b6ca15efb..ca1682f81ffc9 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -242,6 +242,18 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 	return true;
 }
 
+/*
+ * Note the number of natively supported chip selects for MX51 is 4. Some
+ * devices may have less actual SS pins but the register map supports 4. When
+ * using gpio chip selects the cs values passed into the macros below can go
+ * outside the range 0 - 3. We therefore need to limit the cs value to avoid
+ * corrupting bits outside the allocated locations.
+ *
+ * The simplest way to do this is to just mask the cs bits to 2 bits. This
+ * still allows all 4 native chip selects to work as well as gpio chip selects
+ * (which can use any of the 4 chip select configurations).
+ */
+
 #define MX51_ECSPI_CTRL		0x08
 #define MX51_ECSPI_CTRL_ENABLE		(1 <<  0)
 #define MX51_ECSPI_CTRL_XCH		(1 <<  2)
@@ -250,16 +262,16 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 #define MX51_ECSPI_CTRL_DRCTL(drctl)	((drctl) << 16)
 #define MX51_ECSPI_CTRL_POSTDIV_OFFSET	8
 #define MX51_ECSPI_CTRL_PREDIV_OFFSET	12
-#define MX51_ECSPI_CTRL_CS(cs)		((cs) << 18)
+#define MX51_ECSPI_CTRL_CS(cs)		((cs & 3) << 18)
 #define MX51_ECSPI_CTRL_BL_OFFSET	20
 #define MX51_ECSPI_CTRL_BL_MASK		(0xfff << 20)
 
 #define MX51_ECSPI_CONFIG	0x0c
-#define MX51_ECSPI_CONFIG_SCLKPHA(cs)	(1 << ((cs) +  0))
-#define MX51_ECSPI_CONFIG_SCLKPOL(cs)	(1 << ((cs) +  4))
-#define MX51_ECSPI_CONFIG_SBBCTRL(cs)	(1 << ((cs) +  8))
-#define MX51_ECSPI_CONFIG_SSBPOL(cs)	(1 << ((cs) + 12))
-#define MX51_ECSPI_CONFIG_SCLKCTL(cs)	(1 << ((cs) + 20))
+#define MX51_ECSPI_CONFIG_SCLKPHA(cs)	(1 << ((cs & 3) +  0))
+#define MX51_ECSPI_CONFIG_SCLKPOL(cs)	(1 << ((cs & 3) +  4))
+#define MX51_ECSPI_CONFIG_SBBCTRL(cs)	(1 << ((cs & 3) +  8))
+#define MX51_ECSPI_CONFIG_SSBPOL(cs)	(1 << ((cs & 3) + 12))
+#define MX51_ECSPI_CONFIG_SCLKCTL(cs)	(1 << ((cs & 3) + 20))
 
 #define MX51_ECSPI_INT		0x10
 #define MX51_ECSPI_INT_TEEN		(1 <<  0)
-- 
2.39.2