PM / devfreq: passive: Reduce duplicate code when passive_devfreq case

In order to keep the consistent coding style between passive_devfreq
and passive_cpufreq, use common code for handling required opp property.
Also remove the unneed conditional statement and unify the comment
of both passive_devfreq and passive_cpufreq when getting the target frequency.

Tested-by: Chen-Yu Tsai <[e-mail]>
Tested-by: Johnson Wang <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>

drivers/devfreq/governor_passive.c

···
 			= (struct devfreq_passive_data *)devfreq->data;
 	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
 	unsigned long child_freq = ULONG_MAX;
-	struct dev_pm_opp *opp, *p_opp;
 	int i, count;
 
-	/*
-	 * If the devfreq device with passive governor has the specific method
-	 * to determine the next frequency, should use the get_target_freq()
-	 * of struct devfreq_passive_data.
-	 */
-	if (p_data->get_target_freq)
-		return p_data->get_target_freq(devfreq, freq);
+	/* Get target freq via required opps */
+	child_freq = get_target_freq_by_required_opp(parent_devfreq->dev.parent,
+						parent_devfreq->opp_table,
+						devfreq->opp_table, freq);
+	if (child_freq)
+		goto out;
 
-	/*
-	 * If the parent and passive devfreq device uses the OPP table,
-	 * get the next frequency by using the OPP table.
-	 */
-
-	/*
-	 * - parent devfreq device uses the governors except for passive.
-	 * - passive devfreq device uses the passive governor.
-	 *
-	 * Each devfreq has the OPP table. After deciding the new frequency
-	 * from the governor of parent devfreq device, the passive governor
-	 * need to get the index of new frequency on OPP table of parent
-	 * device. And then the index is used for getting the suitable
-	 * new frequency for passive devfreq device.
-	 */
-	if (!devfreq->profile || !devfreq->profile->freq_table
-		|| devfreq->profile->max_state <= 0)
-		return -EINVAL;
-
-	/*
-	 * The passive governor have to get the correct frequency from OPP
-	 * list of parent device. Because in this case, *freq is temporary
-	 * value which is decided by ondemand governor.
-	 */
-	if (devfreq->opp_table && parent_devfreq->opp_table) {
-		p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent,
-						freq, 0);
-		if (IS_ERR(p_opp))
-			return PTR_ERR(p_opp);
-
-		opp = dev_pm_opp_xlate_required_opp(parent_devfreq->opp_table,
-						    devfreq->opp_table, p_opp);
-		dev_pm_opp_put(p_opp);
-
-		if (IS_ERR(opp))
-			goto no_required_opp;
-
-		*freq = dev_pm_opp_get_freq(opp);
-		dev_pm_opp_put(opp);
-
-		return 0;
-	}
-
-no_required_opp:
-	/*
-	 * Get the OPP table's index of decided frequency by governor
-	 * of parent device.
-	 */
+	/* Use interpolation if required opps is not available */
 	for (i = 0; i < parent_devfreq->profile->max_state; i++)
 		if (parent_devfreq->profile->freq_table[i] == *freq)
 			break;
···
 	if (i == parent_devfreq->profile->max_state)
 		return -EINVAL;
 
-	/* Get the suitable frequency by using index of parent device. */
 	if (i < devfreq->profile->max_state) {
 		child_freq = devfreq->profile->freq_table[i];
 	} else {
···
 		child_freq = devfreq->profile->freq_table[count - 1];
 	}
 
-	/* Return the suitable frequency for passive device. */
+out:
 	*freq = child_freq;
 
 	return 0;