From 10b4640833e95eeacaef8060bc1b35e636df3218 Mon Sep 17 00:00:00 2001
From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Date: Fri, 13 Apr 2018 15:44:16 +0300
Subject: [PATCH] spi: sh-msiof: Fix bit field overflow writes to TSCR/RSCR
Git-commit: 10b4640833e95eeacaef8060bc1b35e636df3218
Patch-mainline: v4.17-rc6
References: bsc#1051510
The change fixes a bit field overflow which allows to write to higher
bits while calculating SPI transfer clock and setting BRPS and BRDV
bit fields, the problem is reproduced if 'parent_rate' to 'spi_hz'
ratio is greater than 1024, for instance
p->min_div = 2,
MSO rate = 33333333,
SPI device rate = 10000
results in
k = 5, i.e. BRDV = 0b100 or 1/32 prescaler output,
BRPS = 105,
TSCR value = 0x6804, thus MSSEL and MSIMM bit fields are non-zero.
Fixes: 65d5665bb260 ("spi: sh-msiof: Update calculation of frequency dividing")
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/spi/spi-sh-msiof.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index ae086aab57d5..8171eedbfc90 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -283,6 +283,7 @@ static void sh_msiof_spi_set_clk_regs(struct sh_msiof_spi_priv *p,
}
k = min_t(int, k, ARRAY_SIZE(sh_msiof_spi_div_table) - 1);
+ brps = min_t(int, brps, 32);
scr = sh_msiof_spi_div_table[k].brdv | SCR_BRPS(brps);
sh_msiof_write(p, TSCR, scr);
--
2.18.0