Commit dcb882bd authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Uwe Kleine-König
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pwm: loongson: Fix u32 overflow in waveform calculation 



mul_u64_u64_div_u64() returns an u64 that might be bigger than U32_MAX.
To properly handle this case it must not be directly assigned to an u32
value.

Use a wider type for duty and period to make the idiom:

	duty = mul_u64_u64_div_u64(...)
	if (duty > U32_MAX)
		duty = U32_MAX;

actually work as intended.

Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/44f3c764-8b65-49a9-b3ad-797e9fbb96f5@stanley.mountain


Fixes: 2b62c894 ("pwm: Add Loongson PWM controller support")
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: default avatarBinbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/20250412122124.1636152-2-u.kleine-koenig@baylibre.com


Signed-off-by: default avatarUwe Kleine-König <ukleinek@kernel.org>
parent 29f1d5ca

drivers/pwm/pwm-loongson.c

+1 −1
Original line number Diff line number Diff line
@@ -118,7 +118,7 @@ static int pwm_loongson_enable(struct pwm_chip *chip, struct pwm_device *pwm) 
static int pwm_loongson_config(struct pwm_chip *chip, struct pwm_device *pwm,

			       u64 duty_ns, u64 period_ns)

{

	u32 duty, period;

	u64 duty, period;

	struct pwm_loongson_ddata *ddata = to_pwm_loongson_ddata(chip);



	/* duty = duty_ns * ddata->clk_rate / NSEC_PER_SEC */