pwm: jz4740: Allow selection of PWM channels 0 and 1

The TCU channels 0 and 1 were previously reserved for system tasks, and
thus unavailable for PWM.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-jz4740.c

@@ -33,6 +33,19 @@ static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
 	return container_of(chip, struct jz4740_pwm_chip, chip);
 }
 
+static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
+				   unsigned int channel)
+{
+	/* Enable all TCU channels for PWM use by default except channels 0/1 */
+	u32 pwm_channels_mask = GENMASK(NUM_PWM - 1, 2);
+
+	device_property_read_u32(jz->chip.dev->parent,
+				 "ingenic,pwm-channels-mask",
+				 &pwm_channels_mask);
+
+	return !!(pwm_channels_mask & BIT(channel));
+}
+
 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct jz4740_pwm_chip *jz = to_jz4740(chip);
@@ -40,11 +53,7 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 	char name[16];
 	int err;
 
-	/*
-	 * Timers 0 and 1 are used for system tasks, so they are unavailable
-	 * for use as PWMs.
-	 */
-	if (pwm->hwpwm < 2)
+	if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
 		return -EBUSY;
 
 	snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);