[PATCH v6 05/10] cpufreq: mediatek: Add opp notification support

[Rex-BC Chen]

>From this opp notifier, cpufreq should listen to opp notification and do
proper actions when receiving events of disable and voltage adjustment.

One of the user for this opp notifier is MediaTek SVS.
The MediaTek Smart Voltage Scaling (SVS) is a hardware which calculates
suitable SVS bank voltages to OPP voltage table.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng at mediatek.com>
Signed-off-by: Jia-Wei Chang <jia-wei.chang at mediatek.com>
Signed-off-by: Rex-BC Chen <rex-bc.chen at mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 91 +++++++++++++++++++++++++++---
 1 file changed, 83 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index fe205eca657d..06d80ee06bbf 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -46,6 +46,11 @@ struct mtk_cpu_dvfs_info {
 	int intermediate_voltage;
 	bool need_voltage_tracking;
 	int pre_vproc;
+	/* Avoid race condition for regulators between notify and policy */
+	struct mutex reg_lock;
+	struct notifier_block opp_nb;
+	unsigned int opp_cpu;
+	unsigned long opp_freq;
 	const struct mtk_cpufreq_platform_data *soc_data;
 	int vtrack_max;
 };
@@ -182,6 +187,8 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 
 	pre_freq_hz = clk_get_rate(cpu_clk);
 
+	mutex_lock(&info->reg_lock);
+
 	if (unlikely(info->pre_vproc <= 0))
 		pre_vproc = regulator_get_voltage(info->proc_reg);
 	else
@@ -214,7 +221,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 			dev_err(cpu_dev,
 				"cpu%d: failed to scale up voltage!\n", policy->cpu);
 			mtk_cpufreq_set_voltage(info, pre_vproc);
-			return ret;
+			goto out;
 		}
 	}
 
@@ -224,8 +231,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 		dev_err(cpu_dev,
 			"cpu%d: failed to re-parent cpu clock!\n", policy->cpu);
 		mtk_cpufreq_set_voltage(info, pre_vproc);
-		WARN_ON(1);
-		return ret;
+		goto out;
 	}
 
 	/* Set the original PLL to target rate. */
@@ -235,7 +241,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 			"cpu%d: failed to scale cpu clock rate!\n", policy->cpu);
 		clk_set_parent(cpu_clk, armpll);
 		mtk_cpufreq_set_voltage(info, pre_vproc);
-		return ret;
+		goto out;
 	}
 
 	/* Set parent of CPU clock back to the original PLL. */
@@ -244,8 +250,7 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 		dev_err(cpu_dev,
 			"cpu%d: failed to re-parent cpu clock!\n", policy->cpu);
 		mtk_cpufreq_set_voltage(info, inter_vproc);
-		WARN_ON(1);
-		return ret;
+		goto out;
 	}
 
 	/*
@@ -260,15 +265,72 @@ static int mtk_cpufreq_set_target(struct cpufreq_policy *policy,
 			clk_set_parent(cpu_clk, info->inter_clk);
 			clk_set_rate(armpll, pre_freq_hz);
 			clk_set_parent(cpu_clk, armpll);
-			return ret;
+			goto out;
 		}
 	}
 
-	return 0;
+	info->opp_freq = freq_hz;
+
+out:
+	mutex_unlock(&info->reg_lock);
+
+	return ret;
 }
 
 #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 *new_opp;
+	struct mtk_cpu_dvfs_info *info;
+	unsigned long freq, volt;
+	struct cpufreq_policy *policy;
+	int ret = 0;
+
+	info = container_of(nb, struct mtk_cpu_dvfs_info, opp_nb);
+
+	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
+		freq = dev_pm_opp_get_freq(opp);
+
+		mutex_lock(&info->reg_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->reg_lock);
+	} else if (event == OPP_EVENT_DISABLE) {
+		freq = dev_pm_opp_get_freq(opp);
+
+		/* case of current opp item is disabled */
+		if (info->opp_freq == freq) {
+			freq = 1;
+			new_opp = dev_pm_opp_find_freq_ceil(info->cpu_dev,
+							    &freq);
+			if (IS_ERR(new_opp)) {
+				dev_err(info->cpu_dev,
+					"all opp items are disabled\n");
+				ret = PTR_ERR(new_opp);
+				return notifier_from_errno(ret);
+			}
+
+			dev_pm_opp_put(new_opp);
+			policy = cpufreq_cpu_get(info->opp_cpu);
+			if (policy) {
+				cpufreq_driver_target(policy, freq / 1000,
+						      CPUFREQ_RELATION_L);
+				cpufreq_cpu_put(policy);
+			}
+		}
+	}
+
+	return notifier_from_errno(ret);
+}
+
 static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 {
 	struct device *cpu_dev;
@@ -357,6 +419,18 @@ 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);
 
+	mutex_init(&info->reg_lock);
+
+	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) {
+		dev_err(cpu_dev, "cpu%d: failed to register opp notifier\n", cpu);
+		goto out_disable_inter_clock;
+	}
+
+	info->opp_freq = clk_get_rate(info->cpu_clk);
+
 	/*
 	 * If SRAM regulator is present, software "voltage tracking" is needed
 	 * for this CPU power domain.
@@ -421,6 +495,7 @@ static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
 	}
 
 	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
+	dev_pm_opp_unregister_notifier(info->cpu_dev, &info->opp_nb);
 }
 
 static int mtk_cpufreq_init(struct cpufreq_policy *policy)
-- 
2.18.0