| From foo@baz Sun Jun 17 12:07:33 CEST 2018 |
| From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> |
| Date: Fri, 13 Apr 2018 15:44:16 +0300 |
| Subject: spi: sh-msiof: Fix bit field overflow writes to TSCR/RSCR |
| |
| From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> |
| |
| [ Upstream commit 10b4640833e95eeacaef8060bc1b35e636df3218 ] |
| |
| 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> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/spi/spi-sh-msiof.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- 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(st |
| } |
| |
| 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); |