[v4, 0/8] Add cpufreq and cci devfreq for mt8183, and SVS support

[v4, 0/8] Add cpufreq and cci devfreq for mt8183, and SVS support

[Andrew-sh.Cheng]

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

MT8183 supports CPU DVFS and CCI DVFS, and LITTLE cpus and CCI are in the same voltage domain.
So, this series is to add drivers to handle the voltage coupling between CPU and CCI DVFS.

For SVS support, add OPP_EVENT_ADJUST_VOLTAGE and corresponding reaction.

Change since v3:
 - modify example of dt-binding
 - change rcu implementation in Support adjusting OPP patch
 - Add mutex init in cpufreq driver

Andrew-sh.Cheng (7):
  cpufreq: mediatek: change to regulator_get_optional
  cpufreq: mediatek: add clock enable for intermediate clock
  cpufreq: mediatek: Add support for mt8183
  dt-bindings: devfreq: add compatible for mt8183 cci devfreq
  devfreq: add mediatek cci devfreq
  cpufreq: mediatek: add opp notification for SVS support
  devfreq: mediatek: cci devfreq register opp notification for SVS
    support

Stephen Boyd (1):
  PM / OPP: Support adjusting OPP voltages at runtime

 .../bindings/devfreq/mt8183-cci-devfreq.txt        |  20 ++
 drivers/cpufreq/cpufreq-dt-platdev.c               |   1 +
 drivers/cpufreq/mediatek-cpufreq.c                 |  94 ++++++-
 drivers/devfreq/Kconfig                            |  10 +
 drivers/devfreq/Makefile                           |   1 +
 drivers/devfreq/mt8183-cci-devfreq.c               | 309 +++++++++++++++++++++
 drivers/opp/core.c                                 |  63 +++++
 include/linux/pm_opp.h                             |  11 +
 8 files changed, 507 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/devfreq/mt8183-cci-devfreq.txt
 create mode 100644 drivers/devfreq/mt8183-cci-devfreq.c

-- 
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[v4, 1/8] cpufreq: mediatek: change to regulator_get_optional

[Andrew-sh.Cheng]

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

For new mediatek chip mt8183,
cci and little cluster share the same buck,
so need to modify the attribute of regulator from exclusive to optional

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index f14f3a85f2f7..a370577ffc73 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -338,7 +338,7 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 		goto out_free_resources;
 	}
 
-	proc_reg = regulator_get_exclusive(cpu_dev, "proc");
+	proc_reg = regulator_get_optional(cpu_dev, "proc");
 	if (IS_ERR(proc_reg)) {
 		if (PTR_ERR(proc_reg) == -EPROBE_DEFER)
 			pr_warn("proc regulator for cpu%d not ready, retry.\n",
-- 
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Re: [v4, 1/8] cpufreq: mediatek: change to regulator_get_optional

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> For new mediatek chip mt8183,
> cci and little cluster share the same buck,
> so need to modify the attribute of regulator from exclusive to optional
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index f14f3a85f2f7..a370577ffc73 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -338,7 +338,7 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  		goto out_free_resources;
>  	}
>  
> -	proc_reg = regulator_get_exclusive(cpu_dev, "proc");
> +	proc_reg = regulator_get_optional(cpu_dev, "proc");
>  	if (IS_ERR(proc_reg)) {
>  		if (PTR_ERR(proc_reg) == -EPROBE_DEFER)
>  			pr_warn("proc regulator for cpu%d not ready, retry.\n",

Applied. Thanks.

-- 
viresh

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[v4, 2/8] cpufreq: mediatek: add clock enable for intermediate clock

[Andrew-sh.Cheng]

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

Intermediate clock is not always enabled by ccf in different projects,
so cpufreq should always enable it by itself.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/cpufreq/mediatek-cpufreq.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index a370577ffc73..acd9539e95de 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -368,13 +368,17 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 		goto out_free_resources;
 	}
 
+	ret = clk_prepare_enable(inter_clk);
+	if (ret)
+		goto out_free_opp_table;
+
 	/* Search a safe voltage for intermediate frequency. */
 	rate = clk_get_rate(inter_clk);
 	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
 	if (IS_ERR(opp)) {
 		pr_err("failed to get intermediate opp for cpu%d\n", cpu);
 		ret = PTR_ERR(opp);
-		goto out_free_opp_table;
+		goto out_disable_clock;
 	}
 	info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
 	dev_pm_opp_put(opp);
@@ -393,6 +397,9 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 
 	return 0;
 
+out_disable_clock:
+	clk_disable_unprepare(inter_clk);
+
 out_free_opp_table:
 	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
 
@@ -419,6 +426,10 @@ static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
 		clk_put(info->cpu_clk);
 	if (!IS_ERR(info->inter_clk))
 		clk_put(info->inter_clk);
+	if (!IS_ERR(info->inter_clk)) {
+		clk_disable_unprepare(info->inter_clk);
+		clk_put(info->inter_clk);
+	}
 
 	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
 }
-- 
2.12.5


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Re: [v4, 2/8] cpufreq: mediatek: add clock enable for intermediate clock

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> Intermediate clock is not always enabled by ccf in different projects,
> so cpufreq should always enable it by itself.
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index a370577ffc73..acd9539e95de 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -368,13 +368,17 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  		goto out_free_resources;
>  	}
>  
> +	ret = clk_prepare_enable(inter_clk);
> +	if (ret)
> +		goto out_free_opp_table;
> +
>  	/* Search a safe voltage for intermediate frequency. */
>  	rate = clk_get_rate(inter_clk);
>  	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
>  	if (IS_ERR(opp)) {
>  		pr_err("failed to get intermediate opp for cpu%d\n", cpu);
>  		ret = PTR_ERR(opp);
> -		goto out_free_opp_table;
> +		goto out_disable_clock;
>  	}
>  	info->intermediate_voltage = dev_pm_opp_get_voltage(opp);
>  	dev_pm_opp_put(opp);
> @@ -393,6 +397,9 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
>  
>  	return 0;
>  
> +out_disable_clock:
> +	clk_disable_unprepare(inter_clk);
> +
>  out_free_opp_table:
>  	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
>  
> @@ -419,6 +426,10 @@ static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
>  		clk_put(info->cpu_clk);
>  	if (!IS_ERR(info->inter_clk))
>  		clk_put(info->inter_clk);

Shouldn't you remove this part now ?

> +	if (!IS_ERR(info->inter_clk)) {
> +		clk_disable_unprepare(info->inter_clk);
> +		clk_put(info->inter_clk);
> +	}
>  
>  	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
>  }
> -- 
> 2.12.5

-- 
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[v4, 3/8] cpufreq: mediatek: Add support for mt8183

[Andrew-sh.Cheng]

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

Add compatible string for mediatek mt8183

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/cpufreq/cpufreq-dt-platdev.c | 1 +
 drivers/cpufreq/mediatek-cpufreq.c   | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index 03dc4244ab00..0f7e837a264e 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -117,6 +117,7 @@ static const struct of_device_id blacklist[] __initconst = {
 	{ .compatible = "mediatek,mt817x", },
 	{ .compatible = "mediatek,mt8173", },
 	{ .compatible = "mediatek,mt8176", },
+	{ .compatible = "mediatek,mt8183", },
 
 	{ .compatible = "nvidia,tegra124", },
 	{ .compatible = "nvidia,tegra210", },
diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index acd9539e95de..4dce41b18369 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -546,6 +546,7 @@ static const struct of_device_id mtk_cpufreq_machines[] __initconst = {
 	{ .compatible = "mediatek,mt817x", },
 	{ .compatible = "mediatek,mt8173", },
 	{ .compatible = "mediatek,mt8176", },
+	{ .compatible = "mediatek,mt8183", },
 
 	{ }
 };
-- 
2.12.5


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Re: [v4, 3/8] cpufreq: mediatek: Add support for mt8183

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: "Andrew-sh.Cheng" <andrew-sh.cheng@mediatek.com>
> 
> Add compatible string for mediatek mt8183
> 
> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> ---
>  drivers/cpufreq/cpufreq-dt-platdev.c | 1 +
>  drivers/cpufreq/mediatek-cpufreq.c   | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
> index 03dc4244ab00..0f7e837a264e 100644
> --- a/drivers/cpufreq/cpufreq-dt-platdev.c
> +++ b/drivers/cpufreq/cpufreq-dt-platdev.c
> @@ -117,6 +117,7 @@ static const struct of_device_id blacklist[] __initconst = {
>  	{ .compatible = "mediatek,mt817x", },
>  	{ .compatible = "mediatek,mt8173", },
>  	{ .compatible = "mediatek,mt8176", },
> +	{ .compatible = "mediatek,mt8183", },
>  
>  	{ .compatible = "nvidia,tegra124", },
>  	{ .compatible = "nvidia,tegra210", },
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index acd9539e95de..4dce41b18369 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -546,6 +546,7 @@ static const struct of_device_id mtk_cpufreq_machines[] __initconst = {
>  	{ .compatible = "mediatek,mt817x", },
>  	{ .compatible = "mediatek,mt8173", },
>  	{ .compatible = "mediatek,mt8176", },
> +	{ .compatible = "mediatek,mt8183", },

Had to fix rebase conflict manually for this. Please always rebase on latest
linux-next.

Applied. Thanks.

-- 
viresh

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[v4, 4/8] dt-bindings: devfreq: add compatible for mt8183 cci devfreq

[Andrew-sh.Cheng]

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

This adds dt-binding documentation of cci devfreq
for Mediatek MT8183 SoC platform.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 .../bindings/devfreq/mt8183-cci-devfreq.txt          | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/devfreq/mt8183-cci-devfreq.txt

diff --git a/Documentation/devicetree/bindings/devfreq/mt8183-cci-devfreq.txt b/Documentation/devicetree/bindings/devfreq/mt8183-cci-devfreq.txt
new file mode 100644
index 000000000000..a65a70bb9f09
--- /dev/null
+++ b/Documentation/devicetree/bindings/devfreq/mt8183-cci-devfreq.txt
@@ -0,0 +1,20 @@
+* Mediatek Cache Coherent Interconnect(CCI) frequency device
+
+Required properties:
+- compatible: should contain "mediatek,mt8183-cci" for frequency scaling of CCI
+- clocks: for frequency scaling of CCI
+- clock-names: for frequency scaling of CCI driver to reference
+- regulator: for voltage scaling of CCI
+- operating-points-v2: for frequency scaling of CCI opp table
+
+Example:
+	cci: cci {
+		compatible = "mediatek,mt8183-cci";
+		clocks = <&apmixedsys CLK_APMIXED_CCIPLL>;
+		clock-names = "cci_clock";
+		operating-points-v2 = <&cci_opp>;
+	};
+
+	&cci {
+		proc-supply = <&mt6358_vproc12_reg>;
+	};
\ No newline at end of file
-- 
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[v4, 5/8] devfreq: add mediatek cci devfreq

[Andrew-sh.Cheng]

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

This adds a devfreq driver for the Cache Coherent Interconnect (CCI)
of the Mediatek MT8183.

On the MT8183 the CCI is supplied by the same regulator as the LITTLE
cores. The driver is notified when the regulator voltage changes
(driven by cpufreq) and adjusts the CCI frequency to the maximum
possible value.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/devfreq/Kconfig              |  10 ++
 drivers/devfreq/Makefile             |   1 +
 drivers/devfreq/mt8183-cci-devfreq.c | 247 +++++++++++++++++++++++++++++++++++
 3 files changed, 258 insertions(+)
 create mode 100644 drivers/devfreq/mt8183-cci-devfreq.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index ba98a4e3ad33..0c8204d6b78a 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -92,6 +92,16 @@ config ARM_EXYNOS_BUS_DEVFREQ
 	  and adjusts the operating frequencies and voltages with OPP support.
 	  This does not yet operate with optimal voltages.
 
+config ARM_MT8183_CCI_DEVFREQ
+	tristate "MT8183 CCI DEVFREQ Driver"
+	depends on ARM_MEDIATEK_CPUFREQ
+	help
+		This adds a devfreq driver for Cache Coherent Interconnect
+		of Mediatek MT8183, which is shared the same regulator
+		with cpu cluster.
+		It can track buck voltage and update a proper cci frequency.
+		Use notification to get regulator status.
+
 config ARM_TEGRA_DEVFREQ
 	tristate "Tegra DEVFREQ Driver"
 	depends on ARCH_TEGRA_124_SOC
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 32b8d4d3f12c..817dde779f16 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
 
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
+obj-$(CONFIG_ARM_MT8183_CCI_DEVFREQ)    += mt8183-cci-devfreq.o
 obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
 obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
 
diff --git a/drivers/devfreq/mt8183-cci-devfreq.c b/drivers/devfreq/mt8183-cci-devfreq.c
new file mode 100644
index 000000000000..818a167c442f
--- /dev/null
+++ b/drivers/devfreq/mt8183-cci-devfreq.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 MediaTek Inc.
+
+ * Author: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/devfreq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#include "governor.h"
+
+struct cci_devfreq {
+	struct devfreq *devfreq;
+	struct regulator *proc_reg;
+	unsigned long proc_reg_uV;
+	struct clk *cci_clk;
+	struct notifier_block nb;
+};
+
+static int cci_devfreq_regulator_notifier(struct notifier_block *nb,
+					  unsigned long val, void *data)
+{
+	int ret;
+	struct cci_devfreq *cci_df =
+		container_of(nb, struct cci_devfreq, nb);
+
+	/* deal with reduce frequency */
+	if (val & REGULATOR_EVENT_PRE_VOLTAGE_CHANGE) {
+		struct pre_voltage_change_data *pvc_data = data;
+
+		if (pvc_data->min_uV < pvc_data->old_uV) {
+			cci_df->proc_reg_uV =
+				(unsigned long)(pvc_data->min_uV);
+			mutex_lock(&cci_df->devfreq->lock);
+			ret = update_devfreq(cci_df->devfreq);
+			if (ret)
+				pr_err("Fail to reduce cci frequency: %d\n",
+				       ret);
+			mutex_unlock(&cci_df->devfreq->lock);
+		}
+	} else if ((val & REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE) &&
+	    ((unsigned long)data > cci_df->proc_reg_uV)) {
+		cci_df->proc_reg_uV = (unsigned long)data;
+		mutex_lock(&cci_df->devfreq->lock);
+		ret = update_devfreq(cci_df->devfreq);
+		if (ret)
+			pr_err("Fail to raise cci frequency back: %d\n", ret);
+		mutex_unlock(&cci_df->devfreq->lock);
+	} else if ((val & REGULATOR_EVENT_VOLTAGE_CHANGE) &&
+	    (cci_df->proc_reg_uV < (unsigned long)data)) {
+		/* deal with increase frequency */
+		cci_df->proc_reg_uV = (unsigned long)data;
+		mutex_lock(&cci_df->devfreq->lock);
+		ret = update_devfreq(cci_df->devfreq);
+		if (ret)
+			pr_err("Fail to raise cci frequency: %d\n", ret);
+		mutex_unlock(&cci_df->devfreq->lock);
+	}
+
+	return 0;
+}
+
+static int mtk_cci_governor_get_target(struct devfreq *devfreq,
+				       unsigned long *freq)
+{
+	struct cci_devfreq *cci_df;
+	struct dev_pm_opp *opp;
+
+	cci_df = dev_get_drvdata(devfreq->dev.parent);
+
+	/* find available frequency */
+	opp = dev_pm_opp_find_freq_ceil_by_volt(devfreq->dev.parent,
+						cci_df->proc_reg_uV);
+	*freq = dev_pm_opp_get_freq(opp);
+
+	return 0;
+}
+
+static int mtk_cci_governor_event_handler(struct devfreq *devfreq,
+					  unsigned int event, void *data)
+{
+	int ret;
+	struct cci_devfreq *cci_df;
+	struct notifier_block *nb;
+
+	cci_df = dev_get_drvdata(devfreq->dev.parent);
+	nb = &cci_df->nb;
+
+	switch (event) {
+	case DEVFREQ_GOV_START:
+	case DEVFREQ_GOV_RESUME:
+		nb->notifier_call = cci_devfreq_regulator_notifier;
+		ret = regulator_register_notifier(cci_df->proc_reg,
+						  nb);
+		if (ret)
+			pr_err("%s: failed to add governor: %d\n", __func__,
+			       ret);
+		break;
+
+	case DEVFREQ_GOV_STOP:
+	case DEVFREQ_GOV_SUSPEND:
+		ret = regulator_unregister_notifier(cci_df->proc_reg,
+						    nb);
+		if (ret)
+			pr_err("%s: failed to add governor: %d\n", __func__,
+			       ret);
+		break;
+
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static struct devfreq_governor mtk_cci_devfreq_governor = {
+	.name = "mtk_cci_vmon",
+	.get_target_freq = mtk_cci_governor_get_target,
+	.event_handler = mtk_cci_governor_event_handler,
+	.immutable = true
+};
+
+static int mtk_cci_devfreq_target(struct device *dev, unsigned long *freq,
+				  u32 flags)
+{
+	int ret;
+	struct cci_devfreq *cci_df = dev_get_drvdata(dev);
+
+	if (!cci_df)
+		return -EINVAL;
+
+	ret = clk_set_rate(cci_df->cci_clk, *freq);
+	if (ret) {
+		pr_err("%s: failed cci to set rate: %d\n", __func__,
+		       ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct devfreq_dev_profile cci_devfreq_profile = {
+	.target = mtk_cci_devfreq_target,
+};
+
+static int mtk_cci_devfreq_probe(struct platform_device *pdev)
+{
+	struct device *cci_dev = &pdev->dev;
+	struct cci_devfreq *cci_df;
+	int ret;
+
+	cci_df = devm_kzalloc(cci_dev, sizeof(*cci_df), GFP_KERNEL);
+	if (!cci_df)
+		return -ENOMEM;
+
+	cci_df->cci_clk = devm_clk_get(cci_dev, "cci_clock");
+	ret = PTR_ERR_OR_ZERO(cci_df->cci_clk);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(cci_dev, "failed to get clock for CCI: %d\n",
+				ret);
+		return ret;
+	}
+	cci_df->proc_reg = devm_regulator_get_optional(cci_dev, "proc");
+	ret = PTR_ERR_OR_ZERO(cci_df->proc_reg);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(cci_dev, "failed to get regulator for CCI: %d\n",
+				ret);
+		return ret;
+	}
+
+	ret = dev_pm_opp_of_add_table(cci_dev);
+	if (ret) {
+		dev_err(cci_dev, "Fail to init CCI OPP table: %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, cci_df);
+
+	cci_df->devfreq = devm_devfreq_add_device(cci_dev,
+						  &cci_devfreq_profile,
+						  "mtk_cci_vmon",
+						  NULL);
+	if (IS_ERR(cci_df->devfreq)) {
+		ret = PTR_ERR(cci_df->devfreq);
+		dev_err(cci_dev, "cannot create cci devfreq device:%d\n", ret);
+		dev_pm_opp_of_remove_table(cci_dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const __maybe_unused struct of_device_id
+	mediatek_cci_devfreq_of_match[] = {
+	{ .compatible = "mediatek,mt8183-cci" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mediatek_cci_devfreq_of_match);
+
+static struct platform_driver cci_devfreq_driver = {
+	.probe	= mtk_cci_devfreq_probe,
+	.driver = {
+		.name = "mediatek-cci-devfreq",
+		.of_match_table = of_match_ptr(mediatek_cci_devfreq_of_match),
+	},
+};
+
+static int __init mtk_cci_devfreq_init(void)
+{
+	int ret;
+
+	ret = devfreq_add_governor(&mtk_cci_devfreq_governor);
+	if (ret) {
+		pr_err("%s: failed to add governor: %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = platform_driver_register(&cci_devfreq_driver);
+	if (ret)
+		devfreq_remove_governor(&mtk_cci_devfreq_governor);
+
+	return ret;
+}
+module_init(mtk_cci_devfreq_init)
+
+static void __exit mtk_cci_devfreq_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&mtk_cci_devfreq_governor);
+	if (ret)
+		pr_err("%s: failed to remove governor: %d\n", __func__, ret);
+
+	platform_driver_unregister(&cci_devfreq_driver);
+}
+module_exit(mtk_cci_devfreq_exit)
+
+MODULE_DESCRIPTION("Mediatek CCI devfreq driver");
+MODULE_AUTHOR("Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.12.5


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[v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Andrew-sh.Cheng]

From: Stephen Boyd <sboyd@codeaurora.org>

On some SoCs the Adaptive Voltage Scaling (AVS) technique is
employed to optimize the operating voltage of a device. At a
given frequency, the hardware monitors dynamic factors and either
makes a suggestion for how much to adjust a voltage for the
current frequency, or it automatically adjusts the voltage
without software intervention. Add an API to the OPP library for
the former case, so that AVS type devices can update the voltages
for an OPP when the hardware determines the voltage should
change. The assumption is that drivers like CPUfreq or devfreq
will register for the OPP notifiers and adjust the voltage
according to suggestions that AVS makes.

This patch is devired from [1] submitted by Stephen.
[1] https://lore.kernel.org/patchwork/patch/599279/

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Roger Lu <roger.lu@mediatek.com>
---
 drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h | 11 +++++++++
 2 files changed, 74 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index c094d5d20fd7..407a07f29b12 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
 }
 
 /**
+ * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
+ * @dev:		device for which we do this operation
+ * @freq:		OPP frequency to adjust voltage of
+ * @u_volt:		new OPP voltage
+ *
+ * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
+ * copy operation, returns 0 if no modifcation was done OR modification was
+ * successful.
+ */
+int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
+			      unsigned long u_volt)
+{
+	struct opp_table *opp_table;
+	struct dev_pm_opp *tmp_opp, *opp = ERR_PTR(-ENODEV);
+	int r = 0;
+
+	/* Find the opp_table */
+	opp_table = _find_opp_table(dev);
+	if (IS_ERR(opp_table)) {
+		r = PTR_ERR(opp_table);
+		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
+		return r;
+	}
+
+	mutex_lock(&opp_table->lock);
+
+	/* Do we have the frequency? */
+	list_for_each_entry(tmp_opp, &opp_table->opp_list, node) {
+		if (tmp_opp->rate == freq) {
+			opp = tmp_opp;
+			break;
+		}
+	}
+
+	if (IS_ERR(opp)) {
+		r = PTR_ERR(opp);
+		goto adjust_unlock;
+	}
+
+	/* Is update really needed? */
+	if (opp->supplies->u_volt == u_volt)
+		goto adjust_unlock;
+
+	opp->supplies->u_volt = u_volt;
+
+	dev_pm_opp_get(opp);
+	mutex_unlock(&opp_table->lock);
+
+	/* Notify the voltage change of the OPP */
+	blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_ADJUST_VOLTAGE,
+				     opp);
+
+	dev_pm_opp_put(opp);
+	goto adjust_put_table;
+
+adjust_unlock:
+	mutex_unlock(&opp_table->lock);
+adjust_put_table:
+	dev_pm_opp_put_opp_table(opp_table);
+	return r;
+}
+
+/**
  * dev_pm_opp_enable() - Enable a specific OPP
  * @dev:	device for which we do this operation
  * @freq:	OPP frequency to enable
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index af5021f27cb7..86947d53e8c4 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -22,6 +22,7 @@ struct opp_table;
 
 enum dev_pm_opp_event {
 	OPP_EVENT_ADD, OPP_EVENT_REMOVE, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
+	OPP_EVENT_ADJUST_VOLTAGE,
 };
 
 /**
@@ -111,6 +112,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq,
 void dev_pm_opp_remove(struct device *dev, unsigned long freq);
 void dev_pm_opp_remove_all_dynamic(struct device *dev);
 
+int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
+			      unsigned long u_volt);
+
 int dev_pm_opp_enable(struct device *dev, unsigned long freq);
 
 int dev_pm_opp_disable(struct device *dev, unsigned long freq);
@@ -234,6 +238,13 @@ static inline void dev_pm_opp_remove_all_dynamic(struct device *dev)
 {
 }
 
+static inline int
+dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
+			  unsigned long u_volt)
+{
+	return 0;
+}
+
 static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq)
 {
 	return 0;
-- 
2.12.5


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Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> From: Stephen Boyd <sboyd@codeaurora.org>
> 
> On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> employed to optimize the operating voltage of a device. At a
> given frequency, the hardware monitors dynamic factors and either
> makes a suggestion for how much to adjust a voltage for the
> current frequency, or it automatically adjusts the voltage
> without software intervention. Add an API to the OPP library for
> the former case, so that AVS type devices can update the voltages
> for an OPP when the hardware determines the voltage should
> change. The assumption is that drivers like CPUfreq or devfreq
> will register for the OPP notifiers and adjust the voltage
> according to suggestions that AVS makes.
> 
> This patch is devired from [1] submitted by Stephen.
> [1] https://lore.kernel.org/patchwork/patch/599279/
> 
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Signed-off-by: Roger Lu <roger.lu@mediatek.com>
> ---
>  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 +++++++++
>  2 files changed, 74 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index c094d5d20fd7..407a07f29b12 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
>  }
>  
>  /**
> + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> + * @dev:		device for which we do this operation
> + * @freq:		OPP frequency to adjust voltage of
> + * @u_volt:		new OPP voltage
> + *
> + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> + * copy operation, returns 0 if no modifcation was done OR modification was
> + * successful.
> + */
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt)

Can you please update this to take a triplet instead ? That is what we are
storing in OPP core now a days.

-- 
viresh

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Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Roger Lu]

Dear Viresh,

Sorry for the late reply.

On Mon, 2019-08-19 at 19:18 +0800, Viresh Kumar wrote:
> On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> > From: Stephen Boyd <sboyd@codeaurora.org>
> > 
> > On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> > employed to optimize the operating voltage of a device. At a
> > given frequency, the hardware monitors dynamic factors and either
> > makes a suggestion for how much to adjust a voltage for the
> > current frequency, or it automatically adjusts the voltage
> > without software intervention. Add an API to the OPP library for
> > the former case, so that AVS type devices can update the voltages
> > for an OPP when the hardware determines the voltage should
> > change. The assumption is that drivers like CPUfreq or devfreq
> > will register for the OPP notifiers and adjust the voltage
> > according to suggestions that AVS makes.
> > 
> > This patch is devired from [1] submitted by Stephen.
> > [1] https://lore.kernel.org/patchwork/patch/599279/
> > 
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> > Signed-off-by: Roger Lu <roger.lu@mediatek.com>
> > ---
> >  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/pm_opp.h | 11 +++++++++
> >  2 files changed, 74 insertions(+)
> > 
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index c094d5d20fd7..407a07f29b12 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
> >  }
> >  
> >  /**
> > + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> > + * @dev:		device for which we do this operation
> > + * @freq:		OPP frequency to adjust voltage of
> > + * @u_volt:		new OPP voltage
> > + *
> > + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> > + * copy operation, returns 0 if no modifcation was done OR modification was
> > + * successful.
> > + */
> > +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> > +			      unsigned long u_volt)
> 
> Can you please update this to take a triplet instead ? That is what we are
> storing in OPP core now a days.

I've studied opp/core.c and still don't know meaning of triplet here.
Could you give me more hints (reference API?) about how to take a
triplet instead? Thanks in advance.


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Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Viresh Kumar]

On 01-11-19, 16:08, Roger Lu wrote:
> I've studied opp/core.c and still don't know meaning of triplet here.
> Could you give me more hints (reference API?) about how to take a
> triplet instead? Thanks in advance.

I was hoping you to follow this thread :)

https://lore.kernel.org/linux-arm-kernel/20191016145756.16004-2-s.nawrocki@samsung.com/

I already applied this patch to the OPP tree.

-- 
viresh

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Re: [v4, 6/8] PM / OPP: Support adjusting OPP voltages at runtime

[Matthias Brugger]

On 13/08/2019 15:31, Andrew-sh.Cheng wrote:
> From: Stephen Boyd <sboyd@codeaurora.org>
> 
> On some SoCs the Adaptive Voltage Scaling (AVS) technique is
> employed to optimize the operating voltage of a device. At a
> given frequency, the hardware monitors dynamic factors and either
> makes a suggestion for how much to adjust a voltage for the
> current frequency, or it automatically adjusts the voltage
> without software intervention. Add an API to the OPP library for
> the former case, so that AVS type devices can update the voltages
> for an OPP when the hardware determines the voltage should
> change. The assumption is that drivers like CPUfreq or devfreq
> will register for the OPP notifiers and adjust the voltage
> according to suggestions that AVS makes.
> 
> This patch is devired from [1] submitted by Stephen.
> [1] https://lore.kernel.org/patchwork/patch/599279/
> 
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Signed-off-by: Roger Lu <roger.lu@mediatek.com>

Nit: your signed-off-by tag is missing.

Regards,
Matthias

> ---
>  drivers/opp/core.c     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h | 11 +++++++++
>  2 files changed, 74 insertions(+)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index c094d5d20fd7..407a07f29b12 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -2054,6 +2054,69 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
>  }
>  
>  /**
> + * dev_pm_opp_adjust_voltage() - helper to change the voltage of an OPP
> + * @dev:		device for which we do this operation
> + * @freq:		OPP frequency to adjust voltage of
> + * @u_volt:		new OPP voltage
> + *
> + * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
> + * copy operation, returns 0 if no modifcation was done OR modification was
> + * successful.
> + */
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt)
> +{
> +	struct opp_table *opp_table;
> +	struct dev_pm_opp *tmp_opp, *opp = ERR_PTR(-ENODEV);
> +	int r = 0;
> +
> +	/* Find the opp_table */
> +	opp_table = _find_opp_table(dev);
> +	if (IS_ERR(opp_table)) {
> +		r = PTR_ERR(opp_table);
> +		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
> +		return r;
> +	}
> +
> +	mutex_lock(&opp_table->lock);
> +
> +	/* Do we have the frequency? */
> +	list_for_each_entry(tmp_opp, &opp_table->opp_list, node) {
> +		if (tmp_opp->rate == freq) {
> +			opp = tmp_opp;
> +			break;
> +		}
> +	}
> +
> +	if (IS_ERR(opp)) {
> +		r = PTR_ERR(opp);
> +		goto adjust_unlock;
> +	}
> +
> +	/* Is update really needed? */
> +	if (opp->supplies->u_volt == u_volt)
> +		goto adjust_unlock;
> +
> +	opp->supplies->u_volt = u_volt;
> +
> +	dev_pm_opp_get(opp);
> +	mutex_unlock(&opp_table->lock);
> +
> +	/* Notify the voltage change of the OPP */
> +	blocking_notifier_call_chain(&opp_table->head, OPP_EVENT_ADJUST_VOLTAGE,
> +				     opp);
> +
> +	dev_pm_opp_put(opp);
> +	goto adjust_put_table;
> +
> +adjust_unlock:
> +	mutex_unlock(&opp_table->lock);
> +adjust_put_table:
> +	dev_pm_opp_put_opp_table(opp_table);
> +	return r;
> +}
> +
> +/**
>   * dev_pm_opp_enable() - Enable a specific OPP
>   * @dev:	device for which we do this operation
>   * @freq:	OPP frequency to enable
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index af5021f27cb7..86947d53e8c4 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -22,6 +22,7 @@ struct opp_table;
>  
>  enum dev_pm_opp_event {
>  	OPP_EVENT_ADD, OPP_EVENT_REMOVE, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
> +	OPP_EVENT_ADJUST_VOLTAGE,
>  };
>  
>  /**
> @@ -111,6 +112,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq,
>  void dev_pm_opp_remove(struct device *dev, unsigned long freq);
>  void dev_pm_opp_remove_all_dynamic(struct device *dev);
>  
> +int dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			      unsigned long u_volt);
> +
>  int dev_pm_opp_enable(struct device *dev, unsigned long freq);
>  
>  int dev_pm_opp_disable(struct device *dev, unsigned long freq);
> @@ -234,6 +238,13 @@ static inline void dev_pm_opp_remove_all_dynamic(struct device *dev)
>  {
>  }
>  
> +static inline int
> +dev_pm_opp_adjust_voltage(struct device *dev, unsigned long freq,
> +			  unsigned long u_volt)
> +{
> +	return 0;
> +}
> +
>  static inline int dev_pm_opp_enable(struct device *dev, unsigned long freq)
>  {
>  	return 0;
> 

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[v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Andrew-sh.Cheng]

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 | 78 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 4dce41b18369..9820c8003507 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 +297,74 @@ 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 +451,21 @@ 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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Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> 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 | 78 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index 4dce41b18369..9820c8003507 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 +297,74 @@ 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) {

Does this ever get called for your platform ? Why are you using opp disable ?
Maybe we can avoid it completely.

> +		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 +451,21 @@ 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

-- 
viresh

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Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[andrew-sh.cheng]

On Tue, 2019-08-20 at 11:39 +0800, Viresh Kumar wrote:
> On 13-08-19, 21:31, Andrew-sh.Cheng wrote:
> > 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 | 78 ++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 78 insertions(+)
> > 
> > diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> > index 4dce41b18369..9820c8003507 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 +297,74 @@ 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) {
> 
> Does this ever get called for your platform ? Why are you using opp disable ?
> Maybe we can avoid it completely.
Hi Viresh~
This is due to SVS feature need to fix Vproc for calibration.
When SVS calibration, it want to disable all opp items, except one with
voltae 1.0V. (SVS will change the voltage field of that opp item, if the
corresponding voltage is not 1.0V)
In this way, SVS can make sure there is no other module, include
thermal, will change Vproc by DVFS driver.
After SVS calibration done, SVS will enable those disabled opp items
back.

> 
> > +		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 +451,21 @@ 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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Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 16-10-19, 10:43, andrew-sh.cheng wrote:
> This is due to SVS feature need to fix Vproc for calibration.
> When SVS calibration, it want to disable all opp items, except one with
> voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> corresponding voltage is not 1.0V)
> In this way, SVS can make sure there is no other module, include
> thermal, will change Vproc by DVFS driver.
> After SVS calibration done, SVS will enable those disabled opp items
> back.

But why is this required to be done this way ? Why can't we just update the
voltages without doing this disable/enable dance ?

-- 
viresh

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Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[andrew-sh.cheng]

On Thu, 2019-10-17 at 12:01 +0530, Viresh Kumar wrote:
> On 16-10-19, 10:43, andrew-sh.cheng wrote:
> > This is due to SVS feature need to fix Vproc for calibration.
> > When SVS calibration, it want to disable all opp items, except one with
> > voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> > corresponding voltage is not 1.0V)
> > In this way, SVS can make sure there is no other module, include
> > thermal, will change Vproc by DVFS driver.
> > After SVS calibration done, SVS will enable those disabled opp items
> > back.
> 
> But why is this required to be done this way ? Why can't we just update the
> voltages without doing this disable/enable dance ?
> 
This is because some opp items need voltage larger than 1.0V.
We cannot update the voltage to 1.0V.

If we don't disable these opp items, and DVFS policy want to set these
high frequencies, dvfs driver will set higher voltage to Vproc and SVS
calibration will be fail.


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Re: [v4, 7/8] cpufreq: mediatek: add opp notification for SVS support

[Viresh Kumar]

On 18-10-19, 17:03, andrew-sh.cheng wrote:
> On Thu, 2019-10-17 at 12:01 +0530, Viresh Kumar wrote:
> > On 16-10-19, 10:43, andrew-sh.cheng wrote:
> > > This is due to SVS feature need to fix Vproc for calibration.
> > > When SVS calibration, it want to disable all opp items, except one with
> > > voltae 1.0V. (SVS will change the voltage field of that opp item, if the
> > > corresponding voltage is not 1.0V)
> > > In this way, SVS can make sure there is no other module, include
> > > thermal, will change Vproc by DVFS driver.
> > > After SVS calibration done, SVS will enable those disabled opp items
> > > back.
> > 
> > But why is this required to be done this way ? Why can't we just update the
> > voltages without doing this disable/enable dance ?
> > 
> This is because some opp items need voltage larger than 1.0V.
> We cannot update the voltage to 1.0V.
> 
> If we don't disable these opp items, and DVFS policy want to set these
> high frequencies, dvfs driver will set higher voltage to Vproc and SVS
> calibration will be fail.

Okay.

-- 
viresh

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[v4, 8/8] devfreq: mediatek: cci devfreq register opp notification for SVS support

[Andrew-sh.Cheng]

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

SVS will change the voltage of opp item.
CCI devfreq need to react to change frequency.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
---
 drivers/devfreq/mt8183-cci-devfreq.c | 62 ++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/drivers/devfreq/mt8183-cci-devfreq.c b/drivers/devfreq/mt8183-cci-devfreq.c
index 818a167c442f..bc5c75d55c03 100644
--- a/drivers/devfreq/mt8183-cci-devfreq.c
+++ b/drivers/devfreq/mt8183-cci-devfreq.c
@@ -19,7 +19,10 @@ struct cci_devfreq {
 	struct regulator *proc_reg;
 	unsigned long proc_reg_uV;
 	struct clk *cci_clk;
+	unsigned long freq;
 	struct notifier_block nb;
+	struct notifier_block opp_nb;
+	int cci_min_freq;
 };
 
 static int cci_devfreq_regulator_notifier(struct notifier_block *nb,
@@ -65,17 +68,61 @@ static int cci_devfreq_regulator_notifier(struct notifier_block *nb,
 	return 0;
 }
 
+static int ccidevfreq_opp_notifier(struct notifier_block *nb,
+unsigned long event, void *data)
+{
+	int ret;
+	struct dev_pm_opp *opp = data;
+	struct cci_devfreq *cci_df = container_of(nb, struct cci_devfreq,
+						  opp_nb);
+	unsigned long	freq, volt, cur_volt;
+
+	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
+		freq = dev_pm_opp_get_freq(opp);
+		/* current opp item is changed */
+		if (freq == cci_df->freq) {
+			volt = dev_pm_opp_get_voltage(opp);
+			cur_volt = regulator_get_voltage(cci_df->proc_reg);
+
+			if (volt > cur_volt) {
+				/* need reduce freq */
+				mutex_lock(&cci_df->devfreq->lock);
+				ret = update_devfreq(cci_df->devfreq);
+				if (ret)
+					pr_err("Fail to reduce cci frequency by opp notification: %d\n",
+					       ret);
+				mutex_unlock(&cci_df->devfreq->lock);
+			}
+		}
+
+		if (freq == cci_df->cci_min_freq) {
+			volt = dev_pm_opp_get_voltage(opp);
+			regulator_set_voltage(cci_df->proc_reg, volt, INT_MAX);
+		}
+	}
+
+	return 0;
+}
+
+
 static int mtk_cci_governor_get_target(struct devfreq *devfreq,
 				       unsigned long *freq)
 {
 	struct cci_devfreq *cci_df;
 	struct dev_pm_opp *opp;
+	int ret;
 
 	cci_df = dev_get_drvdata(devfreq->dev.parent);
 
 	/* find available frequency */
 	opp = dev_pm_opp_find_freq_ceil_by_volt(devfreq->dev.parent,
 						cci_df->proc_reg_uV);
+	ret = PTR_ERR_OR_ZERO(opp);
+	if (ret) {
+		pr_err("%s[%d], cannot find opp with voltage=%d: %d\n",
+		       __func__, __LINE__, cci_df->proc_reg_uV, ret);
+		return ret;
+	}
 	*freq = dev_pm_opp_get_freq(opp);
 
 	return 0;
@@ -87,9 +134,11 @@ static int mtk_cci_governor_event_handler(struct devfreq *devfreq,
 	int ret;
 	struct cci_devfreq *cci_df;
 	struct notifier_block *nb;
+	struct notifier_block *opp_nb;
 
 	cci_df = dev_get_drvdata(devfreq->dev.parent);
 	nb = &cci_df->nb;
+	opp_nb = &cci_df->opp_nb;
 
 	switch (event) {
 	case DEVFREQ_GOV_START:
@@ -100,6 +149,8 @@ static int mtk_cci_governor_event_handler(struct devfreq *devfreq,
 		if (ret)
 			pr_err("%s: failed to add governor: %d\n", __func__,
 			       ret);
+		opp_nb->notifier_call = ccidevfreq_opp_notifier;
+		dev_pm_opp_register_notifier(devfreq->dev.parent, opp_nb);
 		break;
 
 	case DEVFREQ_GOV_STOP:
@@ -141,6 +192,8 @@ static int mtk_cci_devfreq_target(struct device *dev, unsigned long *freq,
 		return ret;
 	}
 
+	cci_df->freq = *freq;
+
 	return 0;
 }
 
@@ -152,6 +205,8 @@ static int mtk_cci_devfreq_probe(struct platform_device *pdev)
 {
 	struct device *cci_dev = &pdev->dev;
 	struct cci_devfreq *cci_df;
+	unsigned long freq, volt;
+	struct dev_pm_opp *opp;
 	int ret;
 
 	cci_df = devm_kzalloc(cci_dev, sizeof(*cci_df), GFP_KERNEL);
@@ -181,6 +236,13 @@ static int mtk_cci_devfreq_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* set voltage lower bound */
+	freq = 1;
+	opp = dev_pm_opp_find_freq_ceil(cci_dev, &freq);
+	cci_df->cci_min_freq = dev_pm_opp_get_freq(opp);
+	volt = dev_pm_opp_get_voltage(opp);
+	dev_pm_opp_put(opp);
+
 	platform_set_drvdata(pdev, cci_df);
 
 	cci_df->devfreq = devm_devfreq_add_device(cci_dev,
-- 
2.12.5


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