Message-id: <566A80D5.2070703@samsung.com>
Date:	Fri, 11 Dec 2015 16:52:53 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	myungjoo.ham@...sung.com, k.kozlowski@...sung.com, kgene@...nel.org
Cc:	kyungmin.park@...sung.com, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, linux@....linux.org.uk,
	tjakobi@...h.uni-bielefeld.de, linux.amoon@...il.com,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 01/20] PM / devfreq: exynos: Add generic exynos bus
 frequency driver

Dear MyungJoo,

Almost device tree patches in this series are reviewed by Exynos maintainer.
Could you please review this series?

Best Regards,
Chanwoo Choi

On 2015년 12월 11일 14:07, Chanwoo Choi wrote:
> This patch adds the generic exynos bus frequency driver for AMBA AXI bus
> of sub-blocks in exynos SoC with DEVFREQ framework. The Samsung Exynos SoC
> have the common architecture for bus between DRAM and sub-blocks in SoC.
> This driver can support the generic bus frequency driver for Exynos SoCs.
> 
> In devicetree, Each bus block has a bus clock, regulator, operation-point
> and devfreq-event devices which measure the utilization of each bus block.
> 
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> [linux.amoon: Tested on Odroid U3]
> Tested-by: Anand Moon <linux.amoon@...il.com>
> ---
>  drivers/devfreq/Kconfig             |  15 ++
>  drivers/devfreq/Makefile            |   1 +
>  drivers/devfreq/exynos/Makefile     |   1 +
>  drivers/devfreq/exynos/exynos-bus.c | 449 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 466 insertions(+)
>  create mode 100644 drivers/devfreq/exynos/exynos-bus.c
> 
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index 64281bb2f650..55ec774f794c 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -66,6 +66,21 @@ config DEVFREQ_GOV_USERSPACE
>  
>  comment "DEVFREQ Drivers"
>  
> +config ARM_EXYNOS_BUS_DEVFREQ
> +	bool "ARM EXYNOS Generic Memory Bus DEVFREQ Driver"
> +	depends on ARCH_EXYNOS
> +	select DEVFREQ_GOV_SIMPLE_ONDEMAND
> +	select DEVFREQ_EVENT_EXYNOS_PPMU
> +	select PM_DEVFREQ_EVENT
> +	select PM_OPP
> +	help
> +	  This adds the common DEVFREQ driver for Exynos Memory bus. Exynos
> +	  Memory bus has one more group of memory bus (e.g, MIF and INT block).
> +	  Each memory bus group could contain many memoby bus block. It reads
> +	  PPMU counters of memory controllers by using DEVFREQ-event device
> +	  and adjusts the operating frequencies and voltages with OPP support.
> +	  This does not yet operate with optimal voltages.
> +
>  config ARM_EXYNOS4_BUS_DEVFREQ
>  	bool "ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver"
>  	depends on (CPU_EXYNOS4210 || SOC_EXYNOS4212 || SOC_EXYNOS4412) && !ARCH_MULTIPLATFORM
> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 5134f9ee983d..375ebbb4fcfb 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -6,6 +6,7 @@ obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE)	+= governor_powersave.o
>  obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
>  
>  # DEVFREQ Drivers
> +obj-$(CONFIG_ARCH_EXYNOS)		+= exynos/
>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos/
>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)	+= exynos/
>  obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
> diff --git a/drivers/devfreq/exynos/Makefile b/drivers/devfreq/exynos/Makefile
> index 49bc9175f923..4ec06d322996 100644
> --- a/drivers/devfreq/exynos/Makefile
> +++ b/drivers/devfreq/exynos/Makefile
> @@ -1,3 +1,4 @@
>  # Exynos DEVFREQ Drivers
> +obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
>  obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos_ppmu.o exynos4_bus.o
>  obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)	+= exynos_ppmu.o exynos5_bus.o
> diff --git a/drivers/devfreq/exynos/exynos-bus.c b/drivers/devfreq/exynos/exynos-bus.c
> new file mode 100644
> index 000000000000..f1bc20839650
> --- /dev/null
> +++ b/drivers/devfreq/exynos/exynos-bus.c
> @@ -0,0 +1,449 @@
> +/*
> + * Generic Exynos Bus frequency driver with DEVFREQ Framework
> + *
> + * Copyright (c) 2015 Samsung Electronics Co., Ltd.
> + * Author : Chanwoo Choi <cw00.choi@...sung.com>
> + *
> + * This driver support Exynos Bus frequency feature by using
> + * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/devfreq.h>
> +#include <linux/devfreq-event.h>
> +#include <linux/device.h>
> +#include <linux/export.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#define DEFAULT_SATURATION_RATIO	40
> +
> +struct exynos_bus {
> +	struct device *dev;
> +
> +	struct devfreq *devfreq;
> +	struct devfreq_event_dev **edev;
> +	unsigned int edev_count;
> +	struct mutex lock;
> +
> +	struct dev_pm_opp *curr_opp;
> +
> +	struct regulator *regulator;
> +	struct clk *clk;
> +	int ratio;
> +};
> +
> +/*
> + * Control the devfreq-event device to get the current state of bus
> + */
> +#define exynos_bus_ops_edev(ops)				\
> +static int exynos_bus_##ops(struct exynos_bus *bus)		\
> +{								\
> +	int i, ret;						\
> +								\
> +	for (i = 0; i < bus->edev_count; i++) {			\
> +		if (!bus->edev[i])				\
> +			continue;				\
> +		ret = devfreq_event_##ops(bus->edev[i]);	\
> +		if (ret < 0)					\
> +			return ret;				\
> +	}							\
> +								\
> +	return 0;						\
> +}
> +exynos_bus_ops_edev(enable_edev);
> +exynos_bus_ops_edev(disable_edev);
> +exynos_bus_ops_edev(set_event);
> +
> +static int exynos_bus_get_event(struct exynos_bus *bus,
> +				struct devfreq_event_data *edata)
> +{
> +	struct devfreq_event_data event_data;
> +	unsigned long load_count = 0, total_count = 0;
> +	int i, ret = 0;
> +
> +	for (i = 0; i < bus->edev_count; i++) {
> +		if (!bus->edev[i])
> +			continue;
> +
> +		ret = devfreq_event_get_event(bus->edev[i], &event_data);
> +		if (ret < 0)
> +			return ret;
> +
> +		if (i == 0 || event_data.load_count > load_count) {
> +			load_count = event_data.load_count;
> +			total_count = event_data.total_count;
> +		}
> +	}
> +
> +	edata->load_count = load_count;
> +	edata->total_count = total_count;
> +
> +	return ret;
> +}
> +
> +/*
> + * Must necessary function for devfreq governor
> + */
> +static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
> +{
> +	struct exynos_bus *bus = dev_get_drvdata(dev);
> +	struct dev_pm_opp *new_opp;
> +	unsigned long old_freq, new_freq, old_volt, new_volt;
> +	int ret = 0;
> +
> +	/* Get new opp-bus instance according to new bus clock */
> +	rcu_read_lock();
> +	new_opp = devfreq_recommended_opp(dev, freq, flags);
> +	if (IS_ERR_OR_NULL(new_opp)) {
> +		dev_err(dev, "failed to get recommed opp instance\n");
> +		rcu_read_unlock();
> +		return PTR_ERR(new_opp);
> +	}
> +
> +	new_freq = dev_pm_opp_get_freq(new_opp);
> +	new_volt = dev_pm_opp_get_voltage(new_opp);
> +	old_freq = dev_pm_opp_get_freq(bus->curr_opp);
> +	old_volt = dev_pm_opp_get_voltage(bus->curr_opp);
> +	rcu_read_unlock();
> +
> +	if (old_freq == new_freq)
> +		return 0;
> +
> +	/* Change voltage and frequency according to new OPP level */
> +	mutex_lock(&bus->lock);
> +
> +	if (old_freq < new_freq) {
> +		ret = regulator_set_voltage(bus->regulator, new_volt, new_volt);
> +		if (ret < 0) {
> +			dev_err(bus->dev, "failed to set voltage\n");
> +			regulator_set_voltage(bus->regulator, old_volt,
> +						old_volt);
> +			goto out;
> +		}
> +	}
> +
> +	ret = clk_set_rate(bus->clk, new_freq);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to change clock of bus\n");
> +		clk_set_rate(bus->clk, old_freq);
> +		goto out;
> +	}
> +
> +	if (old_freq > new_freq) {
> +		ret = regulator_set_voltage(bus->regulator, new_volt, new_volt);
> +		if (ret < 0) {
> +			dev_err(bus->dev, "failed to set voltage\n");
> +			regulator_set_voltage(bus->regulator, old_volt,
> +						old_volt);
> +			goto out;
> +		}
> +	}
> +	bus->curr_opp = new_opp;
> +
> +	dev_dbg(dev, "Set the frequency of bus (%ldkHz -> %ldkHz)\n",
> +			old_freq/1000, new_freq/1000);
> +out:
> +	mutex_unlock(&bus->lock);
> +
> +	return ret;
> +}
> +
> +static int exynos_bus_get_dev_status(struct device *dev,
> +				     struct devfreq_dev_status *stat)
> +{
> +	struct exynos_bus *bus = dev_get_drvdata(dev);
> +	struct devfreq_event_data edata;
> +	int ret;
> +
> +	rcu_read_lock();
> +	stat->current_frequency = dev_pm_opp_get_freq(bus->curr_opp);
> +	rcu_read_unlock();
> +
> +	ret = exynos_bus_get_event(bus, &edata);
> +	if (ret < 0) {
> +		stat->total_time = stat->busy_time = 0;
> +		goto err;
> +	}
> +
> +	stat->busy_time = (edata.load_count * 100) / bus->ratio;
> +	stat->total_time = edata.total_count;
> +
> +	dev_dbg(dev, "Usage of devfreq-event : %ld/%ld\n", stat->busy_time,
> +							stat->total_time);
> +
> +err:
> +	ret = exynos_bus_set_event(bus);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to set event to devfreq-event devices\n");
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static void exynos_bus_exit(struct device *dev)
> +{
> +	struct exynos_bus *bus = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = exynos_bus_disable_edev(bus);
> +	if (ret < 0)
> +		dev_warn(dev, "failed to disable the devfreq-event devices\n");
> +
> +	if (bus->regulator)
> +		regulator_disable(bus->regulator);
> +
> +	dev_pm_opp_of_remove_table(dev);
> +}
> +
> +static int exynos_bus_parse_of(struct device_node *np,
> +			      struct exynos_bus *bus)
> +{
> +	struct device *dev = bus->dev;
> +	unsigned long rate;
> +	int i, ret, count, size;
> +
> +	/* Get the clock to provide each bus with source clock */
> +	bus->clk = devm_clk_get(dev, "bus");
> +	if (IS_ERR(bus->clk)) {
> +		dev_err(dev, "failed to get bus clock\n");
> +		return PTR_ERR(bus->clk);
> +	}
> +
> +	ret = clk_prepare_enable(bus->clk);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to get enable clock\n");
> +		return ret;
> +	}
> +
> +	/* Get the freq/voltage OPP table to scale the bus frequency */
> +	rcu_read_lock();
> +	ret = dev_pm_opp_of_add_table(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to get OPP table\n");
> +		rcu_read_unlock();
> +		return ret;
> +	}
> +
> +	rate = clk_get_rate(bus->clk);
> +	bus->curr_opp = dev_pm_opp_find_freq_ceil(dev, &rate);
> +	if (IS_ERR(bus->curr_opp)) {
> +		dev_err(dev, "failed to find dev_pm_opp\n");
> +		rcu_read_unlock();
> +		ret = PTR_ERR(bus->curr_opp);
> +		goto err_opp;
> +	}
> +	rcu_read_unlock();
> +
> +	/* Get the regulator to provide each bus with the power */
> +	bus->regulator = devm_regulator_get(dev, "vdd");
> +	if (IS_ERR(bus->regulator)) {
> +		dev_err(dev, "failed to get VDD regulator\n");
> +		ret = PTR_ERR(bus->regulator);
> +		goto err_opp;
> +	}
> +
> +	ret = regulator_enable(bus->regulator);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable VDD regulator\n");
> +		goto err_opp;
> +	}
> +
> +	/*
> +	 * Get the devfreq-event devices to get the current utilization of
> +	 * buses. This raw data will be used in devfreq ondemand governor.
> +	 */
> +	count = devfreq_event_get_edev_count(dev);
> +	if (count < 0) {
> +		dev_err(dev, "failed to get the count of devfreq-event dev\n");
> +		ret = count;
> +		goto err_regulator;
> +	}
> +	bus->edev_count = count;
> +
> +	size = sizeof(*bus->edev) * count;
> +	bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
> +	if (!bus->edev) {
> +		ret = -ENOMEM;
> +		goto err_regulator;
> +	}
> +
> +	for (i = 0; i < count; i++) {
> +		bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
> +		if (IS_ERR(bus->edev[i])) {
> +			ret = -EPROBE_DEFER;
> +			goto err_regulator;
> +		}
> +	}
> +
> +	/*
> +	 * Optionally, Get the saturation ratio according to Exynos SoC
> +	 * When measuring the utilization of each AXI bus with devfreq-event
> +	 * devices, the measured real cycle might be much lower than the
> +	 * total cycle of bus during sampling rate. In result, the devfreq
> +	 * simple-ondemand governor might not decide to change the current
> +	 * frequency due to too utilization (= real cycle/total cycle).
> +	 * So, this property is used to adjust the utilization when calculating
> +	 * the busy_time in exynos_bus_get_dev_status().
> +	 */
> +	if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
> +		bus->ratio = DEFAULT_SATURATION_RATIO;
> +
> +	return 0;
> +
> +err_regulator:
> +	regulator_disable(bus->regulator);
> +err_opp:
> +	dev_pm_opp_of_remove_table(dev);
> +
> +	return ret;
> +}
> +
> +static int exynos_bus_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct devfreq_dev_profile *profile;
> +	struct devfreq_simple_ondemand_data *ondemand_data;
> +	struct exynos_bus *bus;
> +	int ret;
> +
> +	if (!np) {
> +		dev_err(dev, "failed to find devicetree node\n");
> +		return -EINVAL;
> +	}
> +
> +	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
> +	if (!bus)
> +		return -ENOMEM;
> +	mutex_init(&bus->lock);
> +	bus->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, bus);
> +
> +	/* Parse the device-tree to get the resource information */
> +	ret = exynos_bus_parse_of(np, bus);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Initalize the struct profile and governor data */
> +	profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
> +	if (!profile)
> +		return -ENOMEM;
> +	profile->polling_ms = 50;
> +	profile->target = exynos_bus_target;
> +	profile->get_dev_status = exynos_bus_get_dev_status;
> +	profile->exit = exynos_bus_exit;
> +
> +	ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
> +	if (!ondemand_data)
> +		return -ENOMEM;
> +	ondemand_data->upthreshold = 40;
> +	ondemand_data->downdifferential = 5;
> +
> +	/* Add devfreq device to monitor and handle the exynos bus */
> +	bus->devfreq = devm_devfreq_add_device(dev, profile, "simple_ondemand",
> +						ondemand_data);
> +	if (IS_ERR_OR_NULL(bus->devfreq)) {
> +		dev_err(dev, "failed to add devfreq device\n");
> +		return  PTR_ERR(bus->devfreq);
> +	}
> +
> +	/* Register opp_notifier to catch the change of OPP  */
> +	ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to register opp notifier\n");
> +		return ret;
> +	}
> +
> +	/*
> +	 * Enable devfreq-event to get raw data which is used to determine
> +	 * current bus load.
> +	 */
> +	ret = exynos_bus_enable_edev(bus);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable devfreq-event devices\n");
> +		return ret;
> +	}
> +
> +	ret = exynos_bus_set_event(bus);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to set event to devfreq-event devices\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int exynos_bus_resume(struct device *dev)
> +{
> +	struct exynos_bus *bus = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (bus->regulator) {
> +		ret = regulator_enable(bus->regulator);
> +		if (ret < 0) {
> +			dev_err(dev, "failed to enable VDD regulator\n");
> +			return ret;
> +		}
> +	}
> +
> +	ret = exynos_bus_enable_edev(bus);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable the devfreq-event devices\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int exynos_bus_suspend(struct device *dev)
> +{
> +	struct exynos_bus *bus = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = exynos_bus_disable_edev(bus);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to disable the devfreq-event devices\n");
> +		return ret;
> +	}
> +
> +	if (bus->regulator)
> +		regulator_disable(bus->regulator);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops exynos_bus_pm = {
> +	SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
> +};
> +
> +static const struct of_device_id exynos_bus_of_match[] = {
> +	{ .compatible = "samsung,exynos-bus", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
> +
> +static struct platform_driver exynos_bus_platdrv = {
> +	.probe		= exynos_bus_probe,
> +	.driver = {
> +		.name	= "exynos-bus",
> +		.pm	= &exynos_bus_pm,
> +		.of_match_table = of_match_ptr(exynos_bus_of_match),
> +	},
> +};
> +module_platform_driver(exynos_bus_platdrv);
> +
> +MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
> +MODULE_AUTHOR("Chanwoo Choi <cw00.choi@...sung.com>");
> +MODULE_LICENSE("GPL v2");
> 

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