[v5, PATCH 4/5] cpufreq: mediatek: add opp notification for SVS support

[Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>]

From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>

cpufreq should listen opp notification and do proper actions
when receiving disable and voltage adjustment events,
which are triggered when SVS is enabled.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 79 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 4b0cc50dd93b..7c37ab31230a 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -42,6 +42,10 @@ struct mtk_cpu_dvfs_info {
 	struct list_head list_head;
 	int intermediate_voltage;
 	bool need_voltage_tracking;
+	struct mutex lock; /* avoid notify and policy race condition */
+	struct notifier_block opp_nb;
+	int opp_cpu;
+	unsigned long opp_freq;
 };
 
 static LIST_HEAD(dvfs_info_list);
@@ -231,6 +235,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 	vproc = dev_pm_opp_get_voltage(opp);
 	dev_pm_opp_put(opp);
 
+	mutex_lock(&info->lock);
 	/*
 	 * If the new voltage or the intermediate voltage is higher than the
 	 * current voltage, scale up voltage first.
@@ -242,6 +247,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 			pr_err("cpu%d: failed to scale up voltage!\n",
 			       policy->cpu);
 			mtk_cpufreq_set_voltage(info, old_vproc);
+			mutex_unlock(&info->lock);
 			return ret;
 		}
 	}
@@ -253,6 +259,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 		       policy->cpu);
 		mtk_cpufreq_set_voltage(info, old_vproc);
 		WARN_ON(1);
+		mutex_unlock(&info->lock);
 		return ret;
 	}
 
@@ -263,6 +270,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 		       policy->cpu);
 		clk_set_parent(cpu_clk, armpll);
 		mtk_cpufreq_set_voltage(info, old_vproc);
+		mutex_unlock(&info->lock);
 		return ret;
 	}
 
@@ -273,6 +281,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 		       policy->cpu);
 		mtk_cpufreq_set_voltage(info, inter_vproc);
 		WARN_ON(1);
+		mutex_unlock(&info->lock);
 		return ret;
 	}
 
@@ -288,15 +297,75 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 			clk_set_parent(cpu_clk, info->inter_clk);
 			clk_set_rate(armpll, old_freq_hz);
 			clk_set_parent(cpu_clk, armpll);
+			mutex_unlock(&info->lock);
 			return ret;
 		}
 	}
 
+	info->opp_freq = freq_hz;
+	mutex_unlock(&info->lock);
+
 	return 0;
 }
 
 #define DYNAMIC_POWER "dynamic-power-coefficient"
 
+static int mtk_cpufreq_opp_notifier(struct notifier_block *nb,
+				    unsigned long event, void *data)
+{
+	struct dev_pm_opp *opp = data;
+	struct dev_pm_opp *opp_item;
+	struct mtk_cpu_dvfs_info *info =
+		container_of(nb, struct mtk_cpu_dvfs_info, opp_nb);
+	unsigned long freq, volt;
+	struct cpufreq_policy *policy;
+	int ret = 0;
+
+	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
+		freq = dev_pm_opp_get_freq(opp);
+
+		mutex_lock(&info->lock);
+		if (info->opp_freq == freq) {
+			volt = dev_pm_opp_get_voltage(opp);
+			ret = mtk_cpufreq_set_voltage(info, volt);
+			if (ret)
+				dev_err(info->cpu_dev, "failed to scale voltage: %d\n",
+					ret);
+		}
+		mutex_unlock(&info->lock);
+	} else if (event == OPP_EVENT_DISABLE) {
+		freq = info->opp_freq;
+		opp_item = dev_pm_opp_find_freq_ceil(info->cpu_dev, &freq);
+		if (!IS_ERR(opp_item))
+			dev_pm_opp_put(opp_item);
+		else
+			freq = 0;
+
+		/* case of current opp is disabled */
+		if (freq == 0 || freq != info->opp_freq) {
+			// find an enable opp item
+			freq = 1;
+			opp_item = dev_pm_opp_find_freq_ceil(info->cpu_dev,
+							     &freq);
+			if (!IS_ERR(opp_item)) {
+				dev_pm_opp_put(opp_item);
+				policy = cpufreq_cpu_get(info->opp_cpu);
+				if (policy) {
+					cpufreq_driver_target(policy,
+						freq / 1000,
+						CPUFREQ_RELATION_L);
+					cpufreq_cpu_put(policy);
+				}
+			} else {
+				pr_err("%s: all opp items are disabled\n",
+				       __func__);
+			}
+		}
+	}
+
+	return notifier_from_errno(ret);
+}
+
 static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 {
 	struct device *cpu_dev;
@@ -383,11 +452,21 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 	info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
 	dev_pm_opp_put(opp);
 
+	info->opp_cpu = cpu;
+	info->opp_nb.notifier_call = mtk_cpufreq_opp_notifier;
+	ret = dev_pm_opp_register_notifier(cpu_dev, &info->opp_nb);
+	if (ret) {
+		pr_warn("cannot register opp notification\n");
+		goto out_free_opp_table;
+	}
+
+	mutex_init(&info->lock);
 	info->cpu_dev = cpu_dev;
 	info->proc_reg = proc_reg;
 	info->sram_reg = IS_ERR(sram_reg) ? NULL : sram_reg;
 	info->cpu_clk = cpu_clk;
 	info->inter_clk = inter_clk;
+	info->opp_freq = clk_get_rate(cpu_clk);
 
 	/*
 	 * If SRAM regulator is present, software "voltage tracking" is needed
-- 
2.12.5
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