pwm: atmel: Fix duty cycle calculation in .get_state()

stable inclusion
from stable-5.10.38
commit b22e8f427c3de299c47350caae2a4f80f6d7eb61
bugzilla: 51875
CVE: NA

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

[ Upstream commit 453e8b3d ]

The CDTY register contains the number of inactive cycles. .apply() does
this correctly, however .get_state() got this wrong.

Fixes: 651b510a ("pwm: atmel: Implement .get_state()")
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/pwm/pwm-atmel.c

@@ -319,7 +319,7 @@ static void atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 		cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
 					  atmel_pwm->data->regs.duty);
-		tmp = (u64)cdty * NSEC_PER_SEC;
+		tmp = (u64)(cprd - cdty) * NSEC_PER_SEC;
 		tmp <<= pres;
 		state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate);