[PATCH 3/3] devfreq: add mediatek cci devfreq

[Andrew-sh Cheng <andrew-sh.cheng-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]

From: "Andrew-sh.Cheng" <andrew-sh.cheng-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

For big/little cpu cluster architecture,
not only CPU frequency, but CCI frequency will also affect performance.

Little cores and cci share the same buck in Mediatek mt8183 IC,
so we add a CCI devfreq which will get notification when buck voltage
is changed, then CCI devfreq can set cci frequency as high as possible.

Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 drivers/devfreq/Kconfig              |   9 ++
 drivers/devfreq/Makefile             |   1 +
 drivers/devfreq/mt8183-cci-devfreq.c | 224 +++++++++++++++++++++++++++++++++++
 3 files changed, 234 insertions(+)
 create mode 100644 drivers/devfreq/mt8183-cci-devfreq.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 6a172d3..0b14aab 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -113,6 +113,15 @@ config ARM_RK3399_DMC_DEVFREQ
           It sets the frequency for the memory controller and reads the usage counts
           from hardware.
 
+config ARM_MT8183_CCI_DEVFREQ
+	tristate "MT8183 CCI DEVFREQ Driver"
+	depends on ARM_MEDIATEK_CPUFREQ
+	help
+		This adds devfreq for cci clock
+		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.
+
 source "drivers/devfreq/event/Kconfig"
 
 endif # PM_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 32b8d4d..25afe8c 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
 obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
 obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
 obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
+obj-$(CONFIG_ARM_MT8183_CCI_DEVFREQ)	+= mt8183-cci-devfreq.o
 
 # DEVFREQ Event Drivers
 obj-$(CONFIG_PM_DEVFREQ_EVENT)		+= event/
diff --git a/drivers/devfreq/mt8183-cci-devfreq.c b/drivers/devfreq/mt8183-cci-devfreq.c
new file mode 100644
index 0000000..4837892
--- /dev/null
+++ b/drivers/devfreq/mt8183-cci-devfreq.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2018 MediaTek Inc.
+#include <linux/cpu.h>
+#include <linux/cpufreq.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_data {
+	struct devfreq		*devfreq;
+	struct regulator	*proc_reg;
+	struct clk		*cci_clk;
+	unsigned long		buck_volt;
+	int			volt_increasing;
+	struct notifier_block	nb;
+};
+
+static int mtk_cci_governor_get_target(struct devfreq *devfreq,
+				       unsigned long *freq)
+{
+	struct cci_devfreq_data *cci_devdata;
+	int	i, opp_count;
+	struct dev_pm_opp	*opp;
+	unsigned long	opp_rate, opp_voltage;
+
+	cci_devdata = dev_get_drvdata(devfreq->dev.parent);
+
+	/* find available frequency */
+	opp_count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
+	for (i = 0, opp_rate = ULONG_MAX; i < opp_count; i++, opp_rate--) {
+		opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent,
+						 &opp_rate);
+		opp_voltage = dev_pm_opp_get_voltage(opp);
+		dev_pm_opp_put(opp);
+
+		if (opp_voltage <= cci_devdata->buck_volt)
+			break;
+	}
+	*freq = opp_rate;
+
+	return 0;
+}
+
+static int mtk_cci_governor_event_handler(struct devfreq *devfreq,
+					  unsigned int event, void *data)
+{
+	return 0;
+}
+
+static struct devfreq_governor mtk_cci_devfreq_governor = {
+	.name = "voltage_monitor",
+	.get_target_freq = mtk_cci_governor_get_target,
+	.event_handler = mtk_cci_governor_event_handler,
+};
+
+static int mtk_cci_devfreq_target(struct device *dev, unsigned long *freq,
+				  u32 flags)
+{
+	struct cci_devfreq_data *cci_devdata;
+
+	cci_devdata = dev_get_drvdata(dev);
+
+	clk_set_rate(cci_devdata->cci_clk, *freq);
+
+	return 0;
+}
+
+static struct devfreq_dev_profile cci_devfreq_profile = {
+	.polling_ms	= 0,
+	.target		= mtk_cci_devfreq_target,
+};
+
+static int cci_devfreq_regulator_notifier(struct notifier_block *nb,
+					  unsigned long val, void *data)
+{
+	struct cci_devfreq_data *cci_devdata =
+		container_of(nb, struct cci_devfreq_data, nb);
+
+	/* deal with reduce frequency */
+	if (val & REGULATOR_EVENT_PRE_VOLTAGE_CHANGE) {
+		struct pre_voltage_change_data *pvc_data = data;
+
+		if (pvc_data->old_uV > pvc_data->min_uV) {
+			cci_devdata->volt_increasing = 0;
+			cci_devdata->buck_volt =
+				(unsigned long)(pvc_data->min_uV);
+			mutex_lock(&cci_devdata->devfreq->lock);
+			update_devfreq(cci_devdata->devfreq);
+			mutex_unlock(&cci_devdata->devfreq->lock);
+		} else {
+			cci_devdata->volt_increasing = 1;
+		}
+	}
+	/* deal with abort reduce frequency */
+	if ((val & REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE) ||
+	    /* deal with increase frequency */
+	    ((val & REGULATOR_EVENT_VOLTAGE_CHANGE) &&
+	     cci_devdata->volt_increasing == 1)) {
+		cci_devdata->buck_volt = (unsigned long)data;
+		mutex_lock(&cci_devdata->devfreq->lock);
+		update_devfreq(cci_devdata->devfreq);
+		mutex_unlock(&cci_devdata->devfreq->lock);
+	}
+
+	return 0;
+}
+
+static int mtk_cci_devfreq_probe(struct platform_device *pdev)
+{
+	struct device *cci_dev = &pdev->dev;
+	struct cci_devfreq_data *cci_devdata;
+	struct notifier_block *nb;
+	int ret;
+
+	dev_pm_opp_of_add_table(&pdev->dev);
+
+	cci_devdata = devm_kzalloc(cci_dev, sizeof(*cci_devdata), GFP_KERNEL);
+	if (!cci_devdata)
+		return -ENOMEM;
+	nb = &cci_devdata->nb;
+	cci_devdata->cci_clk = ERR_PTR(-ENODEV);
+	cci_devdata->proc_reg = ERR_PTR(-ENODEV);
+
+	cci_devdata->cci_clk = clk_get(cci_dev, "cci_clock");
+	ret = PTR_ERR_OR_ZERO(cci_devdata->cci_clk);
+	if (ret) {
+		if (ret == -EPROBE_DEFER)
+			pr_err("cci clock not ready, retry\n");
+		else
+			pr_err("no clock for cci: %d\n", ret);
+
+		goto out_free_resources;
+	}
+
+	cci_devdata->proc_reg = regulator_get_optional(cci_dev, "proc");
+	ret = PTR_ERR_OR_ZERO(cci_devdata->proc_reg);
+	if (ret) {
+		if (ret == -EPROBE_DEFER)
+			pr_err("cci regulator not ready, retry\n");
+		else
+			pr_err("no regulator for cci: %d\n", ret);
+
+		goto out_free_resources;
+	}
+
+	platform_set_drvdata(pdev, cci_devdata);
+
+	/* create cci_devfreq and add to cci device.
+	 * governor is voltage_monitor.
+	 * governor will get platform_device data to make decision.
+	 */
+	cci_devdata->devfreq = devm_devfreq_add_device(cci_dev,
+						       &cci_devfreq_profile,
+						       "voltage_monitor",
+						       NULL);
+
+	nb->notifier_call = cci_devfreq_regulator_notifier;
+	regulator_register_notifier(cci_devdata->proc_reg,
+				    nb);
+
+	return 0;
+
+out_free_resources:
+	if (!IS_ERR(cci_devdata->cci_clk))
+		clk_put(cci_devdata->cci_clk);
+	if (!IS_ERR(cci_devdata->proc_reg))
+		regulator_put(cci_devdata->proc_reg);
+
+	return ret;
+}
+
+static const 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 = mediatek_cci_devfreq_of_match,
+	},
+};
+
+static int __init mtk_cci_devfreq_init(void)
+{
+	int ret = 0;
+
+	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 = 0;
+
+	platform_driver_unregister(&cci_devfreq_driver);
+
+	ret = devfreq_remove_governor(&mtk_cci_devfreq_governor);
+	if (ret)
+		pr_err("%s: failed to remove governor: %d\n", __func__, ret);
+}
+module_exit(mtk_cci_devfreq_exit)
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Mediatek CCI devfreq driver");
+MODULE_AUTHOR("andrew-sh.cheng");
+
-- 
1.8.1.1.dirty