power: regulator: pwm: support pwm polarity setting

The latest kernel PWM drivers enable the polarity settings. When system
run from U-Boot to kerenl, if there are differences in polarity set or
duty cycle, the PMW will re-init:
  close -> set polarity and duty cycle -> enable the PWM.
The power supply controled by pwm regulator may have voltage shaking,
which lead to the system not stable.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/power/regulator/pwm_regulator.c

@@ -24,6 +24,12 @@ struct pwm_regulator_info {
 	int pwm_id;
 	/* the period of one PWM cycle */
 	int period_ns;
+	/*
+	 * the polarity of one PWM
+	 * 0: normal polarity
+	 * 1: inverted polarity
+	 */
+	bool polarity;
 	struct udevice *pwm;
 	/* initialize voltage of regulator */
 	unsigned int init_voltage;
@@ -49,7 +55,7 @@ static int pwm_voltage_to_duty_cycle_percentage(struct udevice *dev, int req_uV)
 	int max_uV = priv->max_voltage;
 	int diff = max_uV - min_uV;
 
-	return 100 - (((req_uV * 100) - (min_uV * 100)) / diff);
+	return ((req_uV * 100) - (min_uV * 100)) / diff;
 }
 
 static int pwm_regulator_get_voltage(struct udevice *dev)
@@ -67,6 +73,12 @@ static int pwm_regulator_set_voltage(struct udevice *dev, int uvolt)
 
 	duty_cycle = pwm_voltage_to_duty_cycle_percentage(dev, uvolt);
 
+	ret = pwm_set_invert(priv->pwm, priv->pwm_id, priv->polarity);
+	if (ret) {
+		dev_err(dev, "Failed to init PWM\n");
+		return ret;
+	}
+
 	ret = pwm_set_config(priv->pwm, priv->pwm_id,
 			(priv->period_ns / 100) * duty_cycle, priv->period_ns);
 	if (ret) {
@@ -97,9 +109,9 @@ static int pwm_regulator_ofdata_to_platdata(struct udevice *dev)
 		debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret);
 		return ret;
 	}
-	/* TODO: pwm_id here from device tree if needed */
 
 	priv->period_ns = args.args[1];
+	priv->polarity = args.args[2];
 
 	priv->init_voltage = fdtdec_get_int(blob, node,
 			"regulator-init-microvolt", -1);

drivers/pwm/pwm-uclass.c

@@ -9,6 +9,16 @@
 #include <dm.h>
 #include <pwm.h>
 
+int pwm_set_invert(struct udevice *dev, uint channel, bool polarity)
+{
+	struct pwm_ops *ops = pwm_get_ops(dev);
+
+	if (!ops->set_invert)
+		return -ENOSYS;
+
+	return ops->set_invert(dev, channel, polarity);
+}
+
 int pwm_set_config(struct udevice *dev, uint channel, uint period_ns,
 		   uint duty_ns)
 {

include/pwm.h

@@ -34,6 +34,15 @@ struct pwm_ops {
 	 * @return 0 if OK, -ve on error
 	 */
 	int (*set_enable)(struct udevice *dev, uint channel, bool enable);
+	/**
+	 * set_invert() - Set the PWM invert
+	 *
+	 * @dev:        PWM device to update
+	 * @channel:    PWM channel to update
+	 * @polarity:   true to invert, false to keep normal polarity
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_invert)(struct udevice *dev, uint channel, bool polarity);
 };
 
 #define pwm_get_ops(dev)	((struct pwm_ops *)(dev)->driver->ops)
@@ -60,6 +69,16 @@ int pwm_set_config(struct udevice *dev, uint channel, uint period_ns,
  */
 int pwm_set_enable(struct udevice *dev, uint channel, bool enable);
 
+/**
+ * pwm_set_invert() - Set pwm default polarity
+ *
+ * @dev:	PWM device to update
+ * @channel:	PWM channel to update
+ * @polarity:	true to invert, false to keep normal polarity
+ * @return 0 if OK, -ve on error
+ */
+int pwm_set_invert(struct udevice *dev, uint channel, bool polarity);
+
 /* Legacy interface */
 #ifndef CONFIG_DM_PWM
 int	pwm_init		(int pwm_id, int div, int invert);