pinctrl: single: Fix potential division by zero

stable inclusion
from stable-v5.10.158
commit 302edce1dd426f7e2abfed35563dec8d5aed0667
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7NTXH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=302edce1dd426f7e2abfed35563dec8d5aed0667

--------------------------------

[ Upstream commit 64c15033 ]

There is a possibility of dividing by zero due to the pcs->bits_per_pin
if pcs->fmask() also has a value of zero and called fls
from asm-generic/bitops/builtin-fls.h or arch/x86/include/asm/bitops.h.
The function pcs_probe() has the branch that assigned to fmask 0 before
pcs_allocate_pin_table() was called

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 4e7e8017 ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules")
Signed-off-by: NMaxim Korotkov <korotkov.maxim.s@gmail.com>
Reviewed-by: NTony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20221117123034.27383-1-korotkov.maxim.s@gmail.comSigned-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

drivers/pinctrl/pinctrl-single.c

@@ -726,7 +726,7 @@ static int pcs_allocate_pin_table(struct pcs_device *pcs)
 
 	mux_bytes = pcs->width / BITS_PER_BYTE;
 
-	if (pcs->bits_per_mux) {
+	if (pcs->bits_per_mux && pcs->fmask) {
 		pcs->bits_per_pin = fls(pcs->fmask);
 		nr_pins = (pcs->size * BITS_PER_BYTE) / pcs->bits_per_pin;
 		num_pins_in_register = pcs->width / pcs->bits_per_pin;