regulator: pwm-regulator: Calculate the output voltage for disabled PWMs

If a PWM output is disabled then it's voltage has to be calculated
based on a zero duty cycle (for normal polarity) or duty cycle being
equal to the PWM period (for inverted polarity). Add support for this
to pwm_regulator_get_voltage().
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://msgid.link/r/20240113224628.377993-3-martin.blumenstingl@googlemail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/pwm-regulator.c

@@ -157,6 +157,13 @@ static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
 
 	pwm_get_state(drvdata->pwm, &pstate);
 
+	if (!pstate.enabled) {
+		if (pstate.polarity == PWM_POLARITY_INVERSED)
+			pstate.duty_cycle = pstate.period;
+		else
+			pstate.duty_cycle = 0;
+	}
+
 	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
 	if (voltage < min(max_uV_duty, min_uV_duty) ||
 	    voltage > max(max_uV_duty, min_uV_duty))