openwrt/target/linux/at91/patches-5.10/240-clk-at91-clk-master-check-if-div-or-pres-is-zero.patch

From bb8e6ca274763fa98613dbe8b0833348a1d8fe4d Mon Sep 17 00:00:00 2001
From: Claudiu Beznea <claudiu.beznea@microchip.com>
Date: Mon, 11 Oct 2021 14:27:12 +0300
Subject: [PATCH 240/247] clk: at91: clk-master: check if div or pres is zero

Check if div or pres is zero before using it as argument for ffs().
In case div is zero ffs() will return 0 and thus substracting from
zero will lead to invalid values to be setup in registers.

Fixes: 7a110b9107ed8 ("clk: at91: clk-master: re-factor master clock")
Fixes: 75c88143f3b87 ("clk: at91: clk-master: add master clock support for SAMA7G5")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-9-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/clk/at91/clk-master.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/clk/at91/clk-master.c
+++ b/drivers/clk/at91/clk-master.c
@@ -344,7 +344,7 @@ static int clk_master_pres_set_rate(stru
 
 	else if (pres == 3)
 		pres = MASTER_PRES_MAX;
-	else
+	else if (pres)
 		pres = ffs(pres) - 1;
 
 	spin_lock_irqsave(master->lock, flags);
@@ -757,7 +757,7 @@ static int clk_sama7g5_master_set_rate(s
 
 	if (div == 3)
 		div = MASTER_PRES_MAX;
-	else
+	else if (div)
 		div = ffs(div) - 1;
 
 	spin_lock_irqsave(master->lock, flags);