On Wed, Aug 24, 2011 at 1:22 AM, MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> wrote:
> Four CPUFREQ-like governors are provided as examples.
>
> powersave: use the lowest frequency possible. The user (device) should
> set the polling_ms as 0 because polling is useless for this governor.
>
> performance: use the highest freqeuncy possible. The user (device)
> should set the polling_ms as 0 because polling is useless for this
> governor.
>
> userspace: use the user specified frequency stored at
> devfreq.user_set_freq. With sysfs support in the following patch, a user
> may set the value with the sysfs interface.
>
> simple_ondemand: simplified version of CPUFREQ's ONDEMAND governor.
>
> When a user updates OPP entries (enable/disable/add), OPP framework
> automatically notifies DEVFREQ to update operating frequency
> accordingly. Thus, DEVFREQ users (device drivers) do not need to update
> DEVFREQ manually with OPP entry updates or set polling_ms for powersave
> , performance, userspace, or any other "static" governors.
>
> Note that these are given only as basic examples for governors and any
> devices with DEVFREQ may implement their own governors with the drivers
> and use them.
>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>
> ---
> Changed from v7
> - Userspace uses its own sysfs interface.
>
> Changed from v5
> - Seperated governor files from devfreq.c
> - Allow simple ondemand to be tuned for each device
> ---
> Documentation/ABI/testing/sysfs-devices-power | 9 ++
> drivers/devfreq/Kconfig | 36 ++++++++
> drivers/devfreq/Makefile | 4 +
> drivers/devfreq/governor_performance.c | 24 +++++
> drivers/devfreq/governor_powersave.c | 24 +++++
> drivers/devfreq/governor_simpleondemand.c | 88 ++++++++++++++++++
> drivers/devfreq/governor_userspace.c | 119 +++++++++++++++++++++++++
> include/linux/devfreq.h | 41 +++++++++
> 8 files changed, 345 insertions(+), 0 deletions(-)
> create mode 100644 drivers/devfreq/governor_performance.c
> create mode 100644 drivers/devfreq/governor_powersave.c
> create mode 100644 drivers/devfreq/governor_simpleondemand.c
> create mode 100644 drivers/devfreq/governor_userspace.c
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
> index 57f4591..c7f6977 100644
> --- a/Documentation/ABI/testing/sysfs-devices-power
> +++ b/Documentation/ABI/testing/sysfs-devices-power
> @@ -202,3 +202,12 @@ Description:
> shows the requested polling interval of the corresponding
> device. The values are represented in ms. If the value is less
> than 1 jiffy, it is considered to be 0, which means no polling.
> +
> +What: /sys/devices/.../power/devfreq_userspace_set_freq
How about just .../devfreq_set_freq? I think the userspace bit is
implied and the name is very long.
> +Date: August 2011
> +Contact: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> +Description:
> + The /sys/devices/.../power/devfreq_userspace_set_freq sets
> + and shows the user specified frequency in kHz. This sysfs
> + entry is created and managed by userspace DEVFREQ governor.
> + If other governors are used, it won't be supported.
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index 1fb42de..643b055 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -34,6 +34,42 @@ menuconfig PM_DEVFREQ
>
> if PM_DEVFREQ
>
> +comment "DEVFREQ Governors"
> +
> +config DEVFREQ_GOV_SIMPLE_ONDEMAND
> + bool "Simple Ondemand"
> + help
> + Chooses frequency based on the recent load on the device. Works
> + similar as ONDEMAND governor of CPUFREQ does. A device with
> + Simple-Ondemand should be able to provide busy/total counter
> + values that imply the usage rate. A device may provide tuned
> + values to the governor with data field at devfreq_add_device().
> +
> +config DEVFREQ_GOV_PERFORMANCE
> + bool "Performance"
> + help
> + Sets the frequency at the maximum available frequency.
> + This governor always returns UINT_MAX as frequency so that
> + the DEVFREQ framework returns the highest frequency available
> + at any time.
> +
> +config DEVFREQ_GOV_POWERSAVE
> + bool "Powersave"
> + help
> + Sets the frequency at the minimum available frequency.
> + This governor always returns 0 as frequency so that
> + the DEVFREQ framework returns the lowest frequency available
> + at any time.
> +
> +config DEVFREQ_GOV_USERSPACE
> + bool "Userspace"
> + help
> + Sets the frequency at the user specified one.
> + This governor returns the user configured frequency if there
> + has been an input to /sys/devices/.../power/devfreq_set_freq.
> + Otherwise, the governor does not change the frequnecy
> + given at the initialization.
> +
> comment "DEVFREQ Drivers"
>
> endif # PM_DEVFREQ
> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> index 168934a..4564a89 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -1 +1,5 @@
> obj-$(CONFIG_PM_DEVFREQ) += devfreq.o
> +obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o
> +obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
> +obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
> +obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
> diff --git a/drivers/devfreq/governor_performance.c b/drivers/devfreq/governor_performance.c
> new file mode 100644
> index 0000000..c47eff8
> --- /dev/null
> +++ b/drivers/devfreq/governor_performance.c
> @@ -0,0 +1,24 @@
> +/*
> + * linux/drivers/devfreq/governor_performance.c
> + *
> + * Copyright (C) 2011 Samsung Electronics
> + * MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> + *
> + * 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/devfreq.h>
> +
> +static int devfreq_performance_func(struct devfreq *df,
> + unsigned long *freq)
> +{
> + *freq = UINT_MAX; /* devfreq_do will run "floor" */
> + return 0;
> +}
> +
> +struct devfreq_governor devfreq_performance = {
> + .name = "performance",
> + .get_target_freq = devfreq_performance_func,
> +};
> diff --git a/drivers/devfreq/governor_powersave.c b/drivers/devfreq/governor_powersave.c
> new file mode 100644
> index 0000000..4f128d8
> --- /dev/null
> +++ b/drivers/devfreq/governor_powersave.c
> @@ -0,0 +1,24 @@
> +/*
> + * linux/drivers/devfreq/governor_powersave.c
> + *
> + * Copyright (C) 2011 Samsung Electronics
> + * MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> + *
> + * 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/devfreq.h>
> +
> +static int devfreq_powersave_func(struct devfreq *df,
> + unsigned long *freq)
> +{
> + *freq = 0; /* devfreq_do will run "ceiling" to 0 */
> + return 0;
> +}
> +
> +struct devfreq_governor devfreq_powersave = {
> + .name = "powersave",
> + .get_target_freq = devfreq_powersave_func,
> +};
> diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
> new file mode 100644
> index 0000000..18fe8be
> --- /dev/null
> +++ b/drivers/devfreq/governor_simpleondemand.c
> @@ -0,0 +1,88 @@
> +/*
> + * linux/drivers/devfreq/governor_simpleondemand.c
> + *
> + * Copyright (C) 2011 Samsung Electronics
> + * MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> + *
> + * 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/errno.h>
> +#include <linux/devfreq.h>
> +#include <linux/math64.h>
> +
> +/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
> +#define DFSO_UPTHRESHOLD (90)
> +#define DFSO_DOWNDIFFERENCTIAL (5)
> +static int devfreq_simple_ondemand_func(struct devfreq *df,
> + unsigned long *freq)
> +{
> + struct devfreq_dev_status stat;
> + int err = df->profile->get_dev_status(df->dev, &stat);
> + unsigned long long a, b;
> + unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
> + unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
> + struct devfreq_simple_ondemand_data *data = df->data;
> +
> + if (err)
> + return err;
> +
> + if (data) {
> + if (data->upthreshold)
> + dfso_upthreshold = data->upthreshold;
> + if (data->downdifferential)
> + dfso_downdifferential = data->downdifferential;
> + }
> + if (dfso_upthreshold > 100 ||
> + dfso_upthreshold < dfso_downdifferential)
> + return -EINVAL;
> +
> + /* Assume MAX if it is going to be divided by zero */
> + if (stat.total_time == 0) {
> + *freq = UINT_MAX;
> + return 0;
> + }
> +
> + /* Prevent overflow */
> + if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
> + stat.busy_time >>= 7;
> + stat.total_time >>= 7;
> + }
> +
> + /* Set MAX if it's busy enough */
> + if (stat.busy_time * 100 >
> + stat.total_time * dfso_upthreshold) {
> + *freq = UINT_MAX;
> + return 0;
> + }
> +
> + /* Set MAX if we do not know the initial frequency */
> + if (stat.current_frequency == 0) {
> + *freq = UINT_MAX;
> + return 0;
> + }
> +
> + /* Keep the current frequency */
> + if (stat.busy_time * 100 >
> + stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
> + *freq = stat.current_frequency;
> + return 0;
> + }
> +
> + /* Set the desired frequency based on the load */
> + a = stat.busy_time;
> + a *= stat.current_frequency;
> + b = div_u64(a, stat.total_time);
> + b *= 100;
> + b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
> + *freq = (unsigned long) b;
> +
> + return 0;
> +}
> +
> +struct devfreq_governor devfreq_simple_ondemand = {
> + .name = "simple_ondemand",
> + .get_target_freq = devfreq_simple_ondemand_func,
> +};
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> new file mode 100644
> index 0000000..53a4574
> --- /dev/null
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -0,0 +1,119 @@
> +/*
> + * linux/drivers/devfreq/governor_simpleondemand.c
> + *
> + * Copyright (C) 2011 Samsung Electronics
> + * MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> + *
> + * 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/slab.h>
> +#include <linux/device.h>
> +#include <linux/devfreq.h>
> +#include <linux/pm.h>
> +#include "governor.h"
> +
> +struct userspace_data {
> + unsigned long user_frequency;
> + bool valid;
> +};
> +
> +static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
> +{
> + struct userspace_data *data = df->data;
> +
> + if (!data->valid)
> + *freq = df->previous_freq; /* No user freq specified yet */
> + else
> + *freq = data->user_frequency;
> + return 0;
> +}
> +
> +static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct devfreq *devfreq = get_devfreq(dev);
> + struct userspace_data *data;
> + unsigned long wanted;
> + int err = 0;
> +
> + if (IS_ERR(devfreq)) {
> + err = PTR_ERR(devfreq);
> + goto out;
> + }
> + data = devfreq->data;
> +
> + sscanf(buf, "%lu", &wanted);
> + data->user_frequency = wanted;
> + data->valid = true;
> + err = update_devfreq(devfreq);
> + if (err == 0)
> + err = count;
> +out:
> + return err;
> +}
> +
> +static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct devfreq *devfreq = get_devfreq(dev);
> + struct userspace_data *data;
> + int err = 0;
> +
> + if (IS_ERR(devfreq)) {
> + err = PTR_ERR(devfreq);
> + goto out;
> + }
> + data = devfreq->data;
> +
> + if (data->valid)
> + err = sprintf(buf, "%lu\n", data->user_frequency);
> + else
> + err = sprintf(buf, "undefined\n");
> +out:
> + return err;
> +}
Shouldn't accesses to devfreq->data be protected by a mutex?
Regards,
Mike
> +
> +static DEVICE_ATTR(devfreq_userspace_set_freq, 0644, show_freq, store_freq);
> +static struct attribute *dev_entries[] = {
> + &dev_attr_devfreq_userspace_set_freq.attr,
> + NULL,
> +};
> +static struct attribute_group dev_attr_group = {
> + .name = power_group_name,
> + .attrs = dev_entries,
> +};
> +
> +static int userspace_init(struct devfreq *devfreq)
> +{
> + int err = 0;
> + struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
> + GFP_KERNEL);
> +
> + if (!data) {
> + err = -ENOMEM;
> + goto out;
> + }
> + data->valid = false;
> + devfreq->data = data;
> +
> + sysfs_merge_group(&devfreq->dev->kobj, &dev_attr_group);
> +out:
> + return err;
> +}
> +
> +static void userspace_exit(struct devfreq *devfreq)
> +{
> + sysfs_unmerge_group(&devfreq->dev->kobj, &dev_attr_group);
> + kfree(devfreq->data);
> + devfreq->data = NULL;
> +}
> +
> +struct devfreq_governor devfreq_userspace = {
> + .name = "userspace",
> + .get_target_freq = devfreq_userspace_func,
> + .init = userspace_init,
> + .exit = userspace_exit,
> +};
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index fdc6916..cbafcdf 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -13,6 +13,7 @@
> #ifndef __LINUX_DEVFREQ_H__
> #define __LINUX_DEVFREQ_H__
>
> +#include <linux/opp.h>
> #include <linux/notifier.h>
>
> #define DEVFREQ_NAME_LEN 16
> @@ -65,6 +66,8 @@ struct devfreq_governor {
> * "devfreq_monitor" executions to reevaluate
> * frequency/voltage of the device. Set by
> * profile's polling_ms interval.
> + * @user_set_freq User specified adequete frequency value (thru sysfs
> + * interface). Governors may and may not use this value.
> * @data Private data of the governor. The devfreq framework does not
> * touch this.
> *
> @@ -82,6 +85,7 @@ struct devfreq {
> unsigned long previous_freq;
> unsigned int next_polling;
>
> + unsigned long user_set_freq; /* governors may ignore this. */
> void *data; /* private data for governors */
> };
>
> @@ -91,6 +95,37 @@ extern int devfreq_add_device(struct device *dev,
> struct devfreq_governor *governor,
> void *data);
> extern int devfreq_remove_device(struct device *dev);
> +
> +#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
> +extern struct devfreq_governor devfreq_powersave;
> +#endif
> +#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
> +extern struct devfreq_governor devfreq_performance;
> +#endif
> +#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
> +extern struct devfreq_governor devfreq_userspace;
> +#endif
> +#ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
> +extern struct devfreq_governor devfreq_simple_ondemand;
> +/**
> + * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
> + * and devfreq_add_device
> + * @ upthreshold If the load is over this value, the frequency jumps.
> + * Specify 0 to use the default. Valid value = 0 to 100.
> + * @ downdifferential If the load is under upthreshold - downdifferential,
> + * the governor may consider slowing the frequency down.
> + * Specify 0 to use the default. Valid value = 0 to 100.
> + * downdifferential < upthreshold must hold.
> + *
> + * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
> + * the governor uses the default values.
> + */
> +struct devfreq_simple_ondemand_data {
> + unsigned int upthreshold;
> + unsigned int downdifferential;
> +};
> +#endif
> +
> #else /* !CONFIG_PM_DEVFREQ */
> static int devfreq_add_device(struct device *dev,
> struct devfreq_dev_profile *profile,
> @@ -104,6 +139,12 @@ static int devfreq_remove_device(struct device *dev)
> {
> return 0;
> }
> +
> +#define devfreq_powersave NULL
> +#define devfreq_performance NULL
> +#define devfreq_userspace NULL
> +#define devfreq_simple_ondemand NULL
> +
> #endif /* CONFIG_PM_DEVFREQ */
>
> #endif /* __LINUX_DEVFREQ_H__ */
> --
> 1.7.4.1
>
>
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