pwm: dwc: add PWM bit unset in get_state call

If we are not in PWM mode, then the output is technically a 50%
output based on a single timer instead of the high-low based on
the two counters. Add a check for the PWM mode in dwc_pwm_get_state()
and if DWC_TIM_CTRL_PWM is not set, then return a 50% cycle.

This may only be an issue on initialisation, as the rest of the
code currently assumes we're always going to have the extended
PWM mode using two counters.
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230907161242.67190-4-ben.dooks@codethink.co.ukSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-dwc-core.c

@@ -122,24 +122,32 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct dwc_pwm *dwc = to_dwc_pwm(chip);
 	u64 duty, period;
+	u32 ctrl, ld, ld2;
 
 	pm_runtime_get_sync(chip->dev);
 
-	state->enabled = !!(dwc_pwm_readl(dwc,
-				DWC_TIM_CTRL(pwm->hwpwm)) & DWC_TIM_CTRL_EN);
+	ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm));
+	ld = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
+	ld2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
 
-	duty = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
-	duty += 1;
-	duty *= dwc->clk_ns;
-	state->duty_cycle = duty;
+	state->enabled = !!(ctrl & DWC_TIM_CTRL_EN);
 
-	period = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
-	period += 1;
-	period *= dwc->clk_ns;
-	period += duty;
-	state->period = period;
+	/*
+	 * If we're not in PWM, technically the output is a 50-50
+	 * based on the timer load-count only.
+	 */
+	if (ctrl & DWC_TIM_CTRL_PWM) {
+		duty = (ld + 1) * dwc->clk_ns;
+		period = (ld2 + 1)  * dwc->clk_ns;
+		period += duty;
+	} else {
+		duty = (ld + 1) * dwc->clk_ns;
+		period = duty * 2;
+	}
 
 	state->polarity = PWM_POLARITY_INVERSED;
+	state->period = period;
+	state->duty_cycle = duty;
 
 	pm_runtime_put_sync(chip->dev);