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pwm: loongson: Fix u32 overflow in waveform calculation

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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: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/44f3c764-8b65-49a9-b3ad-797e9fbb96f5@stanley.mountain
Fixes: 2b62c89448 ("pwm: Add Loongson PWM controller support")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/20250412122124.1636152-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This commit is contained in:
Uwe Kleine-König
2025-04-12 14:21:24 +02:00
committed by Uwe Kleine-König
parent 29f1d5cac2
commit dcb882bd43
1 changed files with 1 additions and 1 deletions
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2
drivers/pwm/pwm-loongson.c
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@@ -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 */