linux/drivers/devfreq/exynos-bus.c
Viresh Kumar c8ce82b9b9 devfreq: exynos: Don't use OPP structures outside of RCU locks
The OPP structures are abused to the best here, without understanding
how the OPP core and RCU locks work.

In short, the OPP pointer saved 'struct exynos_bus' can become invalid
under your nose, as the OPP core may free it.

Fix various abuses around OPP structures and calls.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-12-08 01:46:06 +01:00

573 lines
14 KiB
C

/*
* Generic Exynos Bus frequency driver with DEVFREQ Framework
*
* Copyright (c) 2016 Samsung Electronics Co., Ltd.
* Author : Chanwoo Choi <cw00.choi@samsung.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
#define DEFAULT_VOLTAGE_TOLERANCE 2
struct exynos_bus {
struct device *dev;
struct devfreq *devfreq;
struct devfreq_event_dev **edev;
unsigned int edev_count;
struct mutex lock;
unsigned long curr_freq;
struct regulator *regulator;
struct clk *clk;
unsigned int voltage_tolerance;
unsigned 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 simple-ondemand 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, new_volt, tol;
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(new_opp)) {
dev_err(dev, "failed to get recommended 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 = bus->curr_freq;
rcu_read_unlock();
if (old_freq == new_freq)
return 0;
tol = new_volt * bus->voltage_tolerance / 100;
/* Change voltage and frequency according to new OPP level */
mutex_lock(&bus->lock);
if (old_freq < new_freq) {
ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
if (ret < 0) {
dev_err(bus->dev, "failed to set voltage\n");
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_tol(bus->regulator, new_volt, tol);
if (ret < 0) {
dev_err(bus->dev, "failed to set voltage\n");
goto out;
}
}
bus->curr_freq = new_freq;
dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\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;
stat->current_frequency = bus->curr_freq;
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 : %lu/%lu\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);
clk_disable_unprepare(bus->clk);
}
/*
* Must necessary function for devfreq passive governor
*/
static int exynos_bus_passive_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;
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(new_opp)) {
dev_err(dev, "failed to get recommended opp instance\n");
rcu_read_unlock();
return PTR_ERR(new_opp);
}
new_freq = dev_pm_opp_get_freq(new_opp);
old_freq = bus->curr_freq;
rcu_read_unlock();
if (old_freq == new_freq)
return 0;
/* Change the frequency according to new OPP level */
mutex_lock(&bus->lock);
ret = clk_set_rate(bus->clk, new_freq);
if (ret < 0) {
dev_err(dev, "failed to set the clock of bus\n");
goto out;
}
*freq = new_freq;
bus->curr_freq = new_freq;
dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n",
old_freq/1000, new_freq/1000);
out:
mutex_unlock(&bus->lock);
return ret;
}
static void exynos_bus_passive_exit(struct device *dev)
{
struct exynos_bus *bus = dev_get_drvdata(dev);
dev_pm_opp_of_remove_table(dev);
clk_disable_unprepare(bus->clk);
}
static int exynos_bus_parent_parse_of(struct device_node *np,
struct exynos_bus *bus)
{
struct device *dev = bus->dev;
int i, ret, count, size;
/* 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");
return PTR_ERR(bus->regulator);
}
ret = regulator_enable(bus->regulator);
if (ret < 0) {
dev_err(dev, "failed to enable VDD regulator\n");
return ret;
}
/*
* 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;
if (of_property_read_u32(np, "exynos,voltage-tolerance",
&bus->voltage_tolerance))
bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
return 0;
err_regulator:
regulator_disable(bus->regulator);
return ret;
}
static int exynos_bus_parse_of(struct device_node *np,
struct exynos_bus *bus)
{
struct device *dev = bus->dev;
struct dev_pm_opp *opp;
unsigned long rate;
int ret;
/* 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 and voltage from OPP table to scale the bus freq */
ret = dev_pm_opp_of_add_table(dev);
if (ret < 0) {
dev_err(dev, "failed to get OPP table\n");
goto err_clk;
}
rate = clk_get_rate(bus->clk);
rcu_read_lock();
opp = devfreq_recommended_opp(dev, &rate, 0);
if (IS_ERR(opp)) {
dev_err(dev, "failed to find dev_pm_opp\n");
rcu_read_unlock();
ret = PTR_ERR(opp);
goto err_opp;
}
bus->curr_freq = dev_pm_opp_get_freq(opp);
rcu_read_unlock();
return 0;
err_opp:
dev_pm_opp_of_remove_table(dev);
err_clk:
clk_disable_unprepare(bus->clk);
return ret;
}
static int exynos_bus_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node, *node;
struct devfreq_dev_profile *profile;
struct devfreq_simple_ondemand_data *ondemand_data;
struct devfreq_passive_data *passive_data;
struct devfreq *parent_devfreq;
struct exynos_bus *bus;
int ret, max_state;
unsigned long min_freq, max_freq;
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;
profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
if (!profile) {
ret = -ENOMEM;
goto err;
}
node = of_parse_phandle(dev->of_node, "devfreq", 0);
if (node) {
of_node_put(node);
goto passive;
} else {
ret = exynos_bus_parent_parse_of(np, bus);
}
if (ret < 0)
goto err;
/* Initialize the struct profile and governor data for parent device */
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) {
ret = -ENOMEM;
goto err;
}
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(bus->devfreq)) {
dev_err(dev, "failed to add devfreq device\n");
ret = PTR_ERR(bus->devfreq);
goto err;
}
/* 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");
goto err;
}
/*
* 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");
goto err;
}
ret = exynos_bus_set_event(bus);
if (ret < 0) {
dev_err(dev, "failed to set event to devfreq-event devices\n");
goto err;
}
goto out;
passive:
/* Initialize the struct profile and governor data for passive device */
profile->target = exynos_bus_passive_target;
profile->exit = exynos_bus_passive_exit;
/* Get the instance of parent devfreq device */
parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
if (IS_ERR(parent_devfreq)) {
ret = -EPROBE_DEFER;
goto err;
}
passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
if (!passive_data) {
ret = -ENOMEM;
goto err;
}
passive_data->parent = parent_devfreq;
/* Add devfreq device for exynos bus with passive governor */
bus->devfreq = devm_devfreq_add_device(dev, profile, "passive",
passive_data);
if (IS_ERR(bus->devfreq)) {
dev_err(dev,
"failed to add devfreq dev with passive governor\n");
ret = -EPROBE_DEFER;
goto err;
}
out:
max_state = bus->devfreq->profile->max_state;
min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
dev_name(dev), min_freq, max_freq);
return 0;
err:
dev_pm_opp_of_remove_table(dev);
clk_disable_unprepare(bus->clk);
return ret;
}
#ifdef CONFIG_PM_SLEEP
static int exynos_bus_resume(struct device *dev)
{
struct exynos_bus *bus = dev_get_drvdata(dev);
int 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;
}
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@samsung.com>");
MODULE_LICENSE("GPL v2");