linux-kernel - [PATCH V3] pwm: rcar: Use div64_ul instead of do

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Message-Id: <20211118030215.163306-1-deng.changcheng@zte.com.cn>
Date:   Thu, 18 Nov 2021 03:02:15 +0000
From:   cgel.zte@...il.com
To:     u.kleine-koenig@...gutronix.de
Cc:     cgel.zte@...il.com, deng.changcheng@....com.cn,
        lee.jones@...aro.org, linux-kernel@...r.kernel.org,
        linux-pwm@...r.kernel.org, thierry.reding@...il.com,
        zealci@....com.cn
Subject: [PATCH V3] pwm: rcar: Use div64_ul instead of do_div

From: Changcheng Deng <deng.changcheng@....com.cn>

do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@....com.cn>
---
 drivers/pwm/pwm-rcar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index b437192380e2..fb475c188e1e 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -111,7 +111,7 @@ static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
 	u32 cyc, ph;
 
 	one_cycle = (unsigned long long)NSEC_PER_SEC * 100ULL * (1 << div);
-	do_div(one_cycle, clk_rate);
+	one_cycle = div64_ul(one_cycle, clk_rate);
 
 	tmp = period_ns * 100ULL;
 	do_div(tmp, one_cycle);
-- 
2.25.1