blob: 7aa58c29a5edff60ef06be48b4561f40121af324 [file] [log] [blame]
/*
* Copyright (c) 2014, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) "cache-hwmon: " fmt
#include <linux/kernel.h>
#include <linux/sizes.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/ktime.h>
#include <linux/time.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/devfreq.h>
#include "governor.h"
#include "governor_cache_hwmon.h"
struct cache_hwmon_node {
unsigned int cycles_per_low_req;
unsigned int cycles_per_med_req;
unsigned int cycles_per_high_req;
unsigned int min_busy;
unsigned int max_busy;
unsigned int tolerance_mrps;
unsigned int guard_band_mhz;
unsigned int decay_rate;
unsigned long prev_mhz;
ktime_t prev_ts;
bool mon_started;
struct list_head list;
void *orig_data;
struct cache_hwmon *hw;
struct attribute_group *attr_grp;
};
static LIST_HEAD(cache_hwmon_list);
static DEFINE_MUTEX(list_lock);
static int use_cnt;
static DEFINE_MUTEX(state_lock);
#define show_attr(name) \
static ssize_t show_##name(struct device *dev, \
struct device_attribute *attr, char *buf) \
{ \
struct devfreq *df = to_devfreq(dev); \
struct cache_hwmon_node *hw = df->data; \
return snprintf(buf, PAGE_SIZE, "%u\n", hw->name); \
}
#define store_attr(name, _min, _max) \
static ssize_t store_##name(struct device *dev, \
struct device_attribute *attr, const char *buf, \
size_t count) \
{ \
int ret; \
unsigned int val; \
struct devfreq *df = to_devfreq(dev); \
struct cache_hwmon_node *hw = df->data; \
ret = sscanf(buf, "%u", &val); \
if (ret != 1) \
return -EINVAL; \
val = max(val, _min); \
val = min(val, _max); \
hw->name = val; \
return count; \
}
#define gov_attr(__attr, min, max) \
show_attr(__attr) \
store_attr(__attr, min, max) \
static DEVICE_ATTR(__attr, 0644, show_##__attr, store_##__attr)
#define MIN_MS 10U
#define MAX_MS 500U
static struct cache_hwmon_node *find_hwmon_node(struct devfreq *df)
{
struct cache_hwmon_node *node, *found = NULL;
mutex_lock(&list_lock);
list_for_each_entry(node, &cache_hwmon_list, list)
if (node->hw->dev == df->dev.parent ||
node->hw->of_node == df->dev.parent->of_node) {
found = node;
break;
}
mutex_unlock(&list_lock);
return found;
}
static unsigned long measure_mrps_and_set_irq(struct cache_hwmon_node *node,
struct mrps_stats *stat)
{
ktime_t ts;
unsigned int us;
struct cache_hwmon *hw = node->hw;
/*
* Since we are stopping the counters, we don't want this short work
* to be interrupted by other tasks and cause the measurements to be
* wrong. Not blocking interrupts to avoid affecting interrupt
* latency and since they should be short anyway because they run in
* atomic context.
*/
preempt_disable();
ts = ktime_get();
us = ktime_to_us(ktime_sub(ts, node->prev_ts));
if (!us)
us = 1;
hw->meas_mrps_and_set_irq(hw, node->tolerance_mrps, us, stat);
node->prev_ts = ts;
preempt_enable();
dev_dbg(hw->df->dev.parent,
"stat H=%3lu, M=%3lu, L=%3lu, T=%3lu, b=%3u, f=%4lu, us=%d\n",
stat->mrps[HIGH], stat->mrps[MED], stat->mrps[LOW],
stat->mrps[HIGH] + stat->mrps[MED] + stat->mrps[LOW],
stat->busy_percent, hw->df->previous_freq / 1000, us);
return 0;
}
static void compute_cache_freq(struct cache_hwmon_node *node,
struct mrps_stats *mrps, unsigned long *freq)
{
unsigned long new_mhz;
unsigned int busy;
new_mhz = mrps->mrps[HIGH] * node->cycles_per_high_req
+ mrps->mrps[MED] * node->cycles_per_med_req
+ mrps->mrps[LOW] * node->cycles_per_low_req;
busy = max(node->min_busy, mrps->busy_percent);
busy = min(node->max_busy, busy);
new_mhz *= 100;
new_mhz /= busy;
if (new_mhz < node->prev_mhz) {
new_mhz = new_mhz * node->decay_rate + node->prev_mhz
* (100 - node->decay_rate);
new_mhz /= 100;
}
node->prev_mhz = new_mhz;
new_mhz += node->guard_band_mhz;
*freq = new_mhz * 1000;
}
#define TOO_SOON_US (1 * USEC_PER_MSEC)
int update_cache_hwmon(struct cache_hwmon *hwmon)
{
struct cache_hwmon_node *node;
struct devfreq *df;
ktime_t ts;
unsigned int us;
int ret;
if (!hwmon)
return -EINVAL;
df = hwmon->df;
if (!df)
return -ENODEV;
node = df->data;
if (!node)
return -ENODEV;
if (!node->mon_started)
return -EBUSY;
dev_dbg(df->dev.parent, "Got update request\n");
devfreq_monitor_stop(df);
/*
* Don't recalc cache freq if the interrupt comes right after a
* previous cache freq calculation. This is done for two reasons:
*
* 1. Sampling the cache request during a very short duration can
* result in a very inaccurate measurement due to very short
* bursts.
* 2. This can only happen if the limit was hit very close to the end
* of the previous sample period. Which means the current cache
* request estimate is not very off and doesn't need to be
* readjusted.
*/
ts = ktime_get();
us = ktime_to_us(ktime_sub(ts, node->prev_ts));
if (us > TOO_SOON_US) {
mutex_lock(&df->lock);
ret = update_devfreq(df);
if (ret)
dev_err(df->dev.parent,
"Unable to update freq on request!\n");
mutex_unlock(&df->lock);
}
devfreq_monitor_start(df);
return 0;
}
static int devfreq_cache_hwmon_get_freq(struct devfreq *df,
unsigned long *freq,
u32 *flag)
{
struct mrps_stats stat;
struct cache_hwmon_node *node = df->data;
memset(&stat, 0, sizeof(stat));
measure_mrps_and_set_irq(node, &stat);
compute_cache_freq(node, &stat, freq);
return 0;
}
gov_attr(cycles_per_low_req, 1U, 100U);
gov_attr(cycles_per_med_req, 1U, 100U);
gov_attr(cycles_per_high_req, 1U, 100U);
gov_attr(min_busy, 1U, 100U);
gov_attr(max_busy, 1U, 100U);
gov_attr(tolerance_mrps, 0U, 100U);
gov_attr(guard_band_mhz, 0U, 500U);
gov_attr(decay_rate, 0U, 100U);
static struct attribute *dev_attr[] = {
&dev_attr_cycles_per_low_req.attr,
&dev_attr_cycles_per_med_req.attr,
&dev_attr_cycles_per_high_req.attr,
&dev_attr_min_busy.attr,
&dev_attr_max_busy.attr,
&dev_attr_tolerance_mrps.attr,
&dev_attr_guard_band_mhz.attr,
&dev_attr_decay_rate.attr,
NULL,
};
static struct attribute_group dev_attr_group = {
.name = "cache_hwmon",
.attrs = dev_attr,
};
static int start_monitoring(struct devfreq *df)
{
int ret;
struct mrps_stats mrps;
struct device *dev = df->dev.parent;
struct cache_hwmon_node *node;
struct cache_hwmon *hw;
node = find_hwmon_node(df);
if (!node) {
dev_err(dev, "Unable to find HW monitor!\n");
return -ENODEV;
}
hw = node->hw;
hw->df = df;
node->orig_data = df->data;
df->data = node;
node->prev_ts = ktime_get();
node->prev_mhz = 0;
mrps.mrps[HIGH] = (df->previous_freq / 1000) - node->guard_band_mhz;
mrps.mrps[HIGH] /= node->cycles_per_high_req;
mrps.mrps[MED] = mrps.mrps[LOW] = 0;
ret = hw->start_hwmon(hw, &mrps);
if (ret) {
dev_err(dev, "Unable to start HW monitor!\n");
goto err_start;
}
devfreq_monitor_start(df);
node->mon_started = true;
ret = sysfs_create_group(&df->dev.kobj, &dev_attr_group);
if (ret) {
dev_err(dev, "Error creating sys entries!\n");
goto sysfs_fail;
}
return 0;
sysfs_fail:
node->mon_started = false;
devfreq_monitor_stop(df);
hw->stop_hwmon(hw);
err_start:
df->data = node->orig_data;
node->orig_data = NULL;
hw->df = NULL;
return ret;
}
static void stop_monitoring(struct devfreq *df)
{
struct cache_hwmon_node *node = df->data;
struct cache_hwmon *hw = node->hw;
sysfs_remove_group(&df->dev.kobj, &dev_attr_group);
node->mon_started = false;
devfreq_monitor_stop(df);
hw->stop_hwmon(hw);
df->data = node->orig_data;
node->orig_data = NULL;
hw->df = NULL;
}
static int devfreq_cache_hwmon_ev_handler(struct devfreq *df,
unsigned int event, void *data)
{
int ret;
unsigned int sample_ms;
switch (event) {
case DEVFREQ_GOV_START:
sample_ms = df->profile->polling_ms;
sample_ms = max(MIN_MS, sample_ms);
sample_ms = min(MAX_MS, sample_ms);
df->profile->polling_ms = sample_ms;
ret = start_monitoring(df);
if (ret)
return ret;
dev_dbg(df->dev.parent, "Enabled Cache HW monitor governor\n");
break;
case DEVFREQ_GOV_STOP:
stop_monitoring(df);
dev_dbg(df->dev.parent, "Disabled Cache HW monitor governor\n");
break;
case DEVFREQ_GOV_INTERVAL:
sample_ms = *(unsigned int *)data;
sample_ms = max(MIN_MS, sample_ms);
sample_ms = min(MAX_MS, sample_ms);
devfreq_interval_update(df, &sample_ms);
break;
}
return 0;
}
static struct devfreq_governor devfreq_cache_hwmon = {
.name = "cache_hwmon",
.get_target_freq = devfreq_cache_hwmon_get_freq,
.event_handler = devfreq_cache_hwmon_ev_handler,
};
int register_cache_hwmon(struct device *dev, struct cache_hwmon *hwmon)
{
int ret = 0;
struct cache_hwmon_node *node;
if (!hwmon->dev && !hwmon->of_node)
return -EINVAL;
node = devm_kzalloc(dev, sizeof(*node), GFP_KERNEL);
if (!node) {
dev_err(dev, "Unable to register gov. Out of memory!\n");
return -ENOMEM;
}
node->cycles_per_med_req = 20;
node->cycles_per_high_req = 35;
node->min_busy = 100;
node->max_busy = 100;
node->tolerance_mrps = 5;
node->guard_band_mhz = 100;
node->decay_rate = 90;
node->hw = hwmon;
node->attr_grp = &dev_attr_group;
mutex_lock(&state_lock);
if (!use_cnt) {
ret = devfreq_add_governor(&devfreq_cache_hwmon);
if (!ret)
use_cnt++;
}
mutex_unlock(&state_lock);
if (!ret) {
dev_info(dev, "Cache HWmon governor registered.\n");
} else {
dev_err(dev, "Failed to add Cache HWmon governor\n");
return ret;
}
mutex_lock(&list_lock);
list_add_tail(&node->list, &cache_hwmon_list);
mutex_unlock(&list_lock);
return ret;
}
MODULE_DESCRIPTION("HW monitor based cache freq driver");
MODULE_LICENSE("GPL v2");