ODROID: Revert "pwm: Drop support for legacy drivers"

This reverts commit 0829c35.

Change-Id: Ib3d3db65304aef8e1d5251ef3b2ee3d302a2504f

drivers/pwm/core.c

@@ -247,8 +247,18 @@ EXPORT_SYMBOL_GPL(pwm_get_chip_data);
 
 static bool pwm_ops_check(const struct pwm_chip *chip)
 {
+
 	const struct pwm_ops *ops = chip->ops;
 
+	/* driver supports legacy, non-atomic operation */
+	if (ops->config && ops->enable && ops->disable) {
+		if (IS_ENABLED(CONFIG_PWM_DEBUG))
+			dev_warn(chip->dev,
+				 "Driver needs updating to atomic API\n");
+
+		return true;
+	}
+
 	if (!ops->apply)
 		return false;
 
@@ -548,6 +558,73 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 	}
 }
 
+static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	int err;
+	struct pwm_state initial_state = pwm->state;
+
+	if (state->polarity != pwm->state.polarity) {
+		if (!chip->ops->set_polarity)
+			return -EINVAL;
+
+		/*
+		 * Changing the polarity of a running PWM is only allowed when
+		 * the PWM driver implements ->apply().
+		 */
+		if (pwm->state.enabled) {
+			chip->ops->disable(chip, pwm);
+
+			/*
+			 * Update pwm->state already here in case
+			 * .set_polarity() or another callback depend on that.
+			 */
+			pwm->state.enabled = false;
+		}
+
+		err = chip->ops->set_polarity(chip, pwm, state->polarity);
+		if (err)
+			goto rollback;
+
+		pwm->state.polarity = state->polarity;
+	}
+
+	if (!state->enabled) {
+		if (pwm->state.enabled)
+			chip->ops->disable(chip, pwm);
+
+		return 0;
+	}
+
+	/*
+	 * We cannot skip calling ->config even if state->period ==
+	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
+	 * because we might have exited early in the last call to
+	 * pwm_apply_state because of !state->enabled and so the two values in
+	 * pwm->state might not be configured in hardware.
+	 */
+	err = chip->ops->config(pwm->chip, pwm,
+				state->duty_cycle,
+				state->period);
+	if (err)
+		goto rollback;
+
+	pwm->state.period = state->period;
+	pwm->state.duty_cycle = state->duty_cycle;
+
+	if (!pwm->state.enabled) {
+		err = chip->ops->enable(chip, pwm);
+		if (err)
+			goto rollback;
+	}
+
+	return 0;
+
+rollback:
+	pwm->state = initial_state;
+	return err;
+}
+
 /**
  * pwm_apply_state() - atomically apply a new state to a PWM device
  * @pwm: PWM device
@@ -580,8 +657,12 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 	    state->usage_power == pwm->state.usage_power)
 		return 0;
 
-	err = chip->ops->apply(chip, pwm, state);
-	trace_pwm_apply(pwm, state, err);
+	if (chip->ops->apply) {
+		err = chip->ops->apply(chip, pwm, state);
+		trace_pwm_apply(pwm, state, err);
+	} else {
+		err = pwm_apply_legacy(chip, pwm, state);
+	}
 	if (err)
 		return err;
 

include/linux/pwm.h

@@ -268,6 +268,10 @@ struct pwm_capture {
  *	       called once per PWM device when the PWM chip is
  *	       registered.
  * @owner: helps prevent removal of modules exporting active PWMs
+ * @config: configure duty cycles and period length for this PWM
+ * @set_polarity: configure the polarity of this PWM
+ * @enable: enable PWM output toggling
+ * @disable: disable PWM output toggling
  */
 struct pwm_ops {
 	int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
@@ -279,6 +283,14 @@ struct pwm_ops {
 	int (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 			 struct pwm_state *state);
 	struct module *owner;
+
+	/* Only used by legacy drivers */
+	int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
+		      int duty_ns, int period_ns);
+	int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
+			    enum pwm_polarity polarity);
+	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
+	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 };
 
 /**