[PATCH 4.19 67/86] spi: bcm-qspi: check for valid cs before applying chip select

Greg Kroah-Hartman
2022-02-07T11:26:08Z

From: Kamal Dasu <kdasu.kdev@gmail.com>

commit 2cbd27267ffe020af1442b95ec57f59a157ba85c upstream.

Apply only valid chip select value. This change fixes case where chip
select is set to initial value of '-1' during probe and PM supend and
subsequent resume can try to use the value with undefined behaviour.
Also in case where gpio based chip select, the check in
bcm_qspi_chip_select() shall prevent undefined behaviour on resume.

Fixes: fa236a7ef240 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220127185359.27322-1-kdasu.kdev@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/spi/spi-bcm-qspi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -520,7 +520,7 @@ static void bcm_qspi_chip_select(struct
u32 rd = 0;
u32 wr = 0;

- if (qspi->base[CHIP_SELECT]) {
+ if (cs >= 0 && qspi->base[CHIP_SELECT]) {
rd = bcm_qspi_read(qspi, CHIP_SELECT, 0);
wr = (rd & ~0xff) | (1 << cs);
if (rd == wr)