https://github.com/torvalds/linux
Tip revision: 18558cae0272f8fd9647e69d3fec1565a7949865 authored by Linus Torvalds on 14 February 2016, 21:05:20 UTC
Linux 4.5-rc4
Linux 4.5-rc4
Tip revision: 18558ca
windfarm_core.c
/*
* Windfarm PowerMac thermal control. Core
*
* (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
* <benh@kernel.crashing.org>
*
* Released under the term of the GNU GPL v2.
*
* This core code tracks the list of sensors & controls, register
* clients, and holds the kernel thread used for control.
*
* TODO:
*
* Add some information about sensor/control type and data format to
* sensors/controls, and have the sysfs attribute stuff be moved
* generically here instead of hard coded in the platform specific
* driver as it us currently
*
* This however requires solving some annoying lifetime issues with
* sysfs which doesn't seem to have lifetime rules for struct attribute,
* I may have to create full features kobjects for every sensor/control
* instead which is a bit of an overkill imho
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/jiffies.h>
#include <linux/reboot.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <asm/prom.h>
#include "windfarm.h"
#define VERSION "0.2"
#undef DEBUG
#ifdef DEBUG
#define DBG(args...) printk(args)
#else
#define DBG(args...) do { } while(0)
#endif
static LIST_HEAD(wf_controls);
static LIST_HEAD(wf_sensors);
static DEFINE_MUTEX(wf_lock);
static BLOCKING_NOTIFIER_HEAD(wf_client_list);
static int wf_client_count;
static unsigned int wf_overtemp;
static unsigned int wf_overtemp_counter;
struct task_struct *wf_thread;
static struct platform_device wf_platform_device = {
.name = "windfarm",
};
/*
* Utilities & tick thread
*/
static inline void wf_notify(int event, void *param)
{
blocking_notifier_call_chain(&wf_client_list, event, param);
}
static int wf_critical_overtemp(void)
{
static char * critical_overtemp_path = "/sbin/critical_overtemp";
char *argv[] = { critical_overtemp_path, NULL };
static char *envp[] = { "HOME=/",
"TERM=linux",
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
NULL };
return call_usermodehelper(critical_overtemp_path,
argv, envp, UMH_WAIT_EXEC);
}
static int wf_thread_func(void *data)
{
unsigned long next, delay;
next = jiffies;
DBG("wf: thread started\n");
set_freezable();
while (!kthread_should_stop()) {
try_to_freeze();
if (time_after_eq(jiffies, next)) {
wf_notify(WF_EVENT_TICK, NULL);
if (wf_overtemp) {
wf_overtemp_counter++;
/* 10 seconds overtemp, notify userland */
if (wf_overtemp_counter > 10)
wf_critical_overtemp();
/* 30 seconds, shutdown */
if (wf_overtemp_counter > 30) {
printk(KERN_ERR "windfarm: Overtemp "
"for more than 30"
" seconds, shutting down\n");
machine_power_off();
}
}
next += HZ;
}
delay = next - jiffies;
if (delay <= HZ)
schedule_timeout_interruptible(delay);
}
DBG("wf: thread stopped\n");
return 0;
}
static void wf_start_thread(void)
{
wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
if (IS_ERR(wf_thread)) {
printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
PTR_ERR(wf_thread));
wf_thread = NULL;
}
}
static void wf_stop_thread(void)
{
if (wf_thread)
kthread_stop(wf_thread);
wf_thread = NULL;
}
/*
* Controls
*/
static void wf_control_release(struct kref *kref)
{
struct wf_control *ct = container_of(kref, struct wf_control, ref);
DBG("wf: Deleting control %s\n", ct->name);
if (ct->ops && ct->ops->release)
ct->ops->release(ct);
else
kfree(ct);
}
static ssize_t wf_show_control(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
const char *typestr;
s32 val = 0;
int err;
err = ctrl->ops->get_value(ctrl, &val);
if (err < 0) {
if (err == -EFAULT)
return sprintf(buf, "<HW FAULT>\n");
return err;
}
switch(ctrl->type) {
case WF_CONTROL_RPM_FAN:
typestr = " RPM";
break;
case WF_CONTROL_PWM_FAN:
typestr = " %";
break;
default:
typestr = "";
}
return sprintf(buf, "%d%s\n", val, typestr);
}
/* This is really only for debugging... */
static ssize_t wf_store_control(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
int val;
int err;
char *endp;
val = simple_strtoul(buf, &endp, 0);
while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
++endp;
if (endp - buf < count)
return -EINVAL;
err = ctrl->ops->set_value(ctrl, val);
if (err < 0)
return err;
return count;
}
int wf_register_control(struct wf_control *new_ct)
{
struct wf_control *ct;
mutex_lock(&wf_lock);
list_for_each_entry(ct, &wf_controls, link) {
if (!strcmp(ct->name, new_ct->name)) {
printk(KERN_WARNING "windfarm: trying to register"
" duplicate control %s\n", ct->name);
mutex_unlock(&wf_lock);
return -EEXIST;
}
}
kref_init(&new_ct->ref);
list_add(&new_ct->link, &wf_controls);
sysfs_attr_init(&new_ct->attr.attr);
new_ct->attr.attr.name = new_ct->name;
new_ct->attr.attr.mode = 0644;
new_ct->attr.show = wf_show_control;
new_ct->attr.store = wf_store_control;
if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
printk(KERN_WARNING "windfarm: device_create_file failed"
" for %s\n", new_ct->name);
/* the subsystem still does useful work without the file */
DBG("wf: Registered control %s\n", new_ct->name);
wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_register_control);
void wf_unregister_control(struct wf_control *ct)
{
mutex_lock(&wf_lock);
list_del(&ct->link);
mutex_unlock(&wf_lock);
DBG("wf: Unregistered control %s\n", ct->name);
kref_put(&ct->ref, wf_control_release);
}
EXPORT_SYMBOL_GPL(wf_unregister_control);
int wf_get_control(struct wf_control *ct)
{
if (!try_module_get(ct->ops->owner))
return -ENODEV;
kref_get(&ct->ref);
return 0;
}
EXPORT_SYMBOL_GPL(wf_get_control);
void wf_put_control(struct wf_control *ct)
{
struct module *mod = ct->ops->owner;
kref_put(&ct->ref, wf_control_release);
module_put(mod);
}
EXPORT_SYMBOL_GPL(wf_put_control);
/*
* Sensors
*/
static void wf_sensor_release(struct kref *kref)
{
struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
DBG("wf: Deleting sensor %s\n", sr->name);
if (sr->ops && sr->ops->release)
sr->ops->release(sr);
else
kfree(sr);
}
static ssize_t wf_show_sensor(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
s32 val = 0;
int err;
err = sens->ops->get_value(sens, &val);
if (err < 0)
return err;
return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
}
int wf_register_sensor(struct wf_sensor *new_sr)
{
struct wf_sensor *sr;
mutex_lock(&wf_lock);
list_for_each_entry(sr, &wf_sensors, link) {
if (!strcmp(sr->name, new_sr->name)) {
printk(KERN_WARNING "windfarm: trying to register"
" duplicate sensor %s\n", sr->name);
mutex_unlock(&wf_lock);
return -EEXIST;
}
}
kref_init(&new_sr->ref);
list_add(&new_sr->link, &wf_sensors);
sysfs_attr_init(&new_sr->attr.attr);
new_sr->attr.attr.name = new_sr->name;
new_sr->attr.attr.mode = 0444;
new_sr->attr.show = wf_show_sensor;
new_sr->attr.store = NULL;
if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
printk(KERN_WARNING "windfarm: device_create_file failed"
" for %s\n", new_sr->name);
/* the subsystem still does useful work without the file */
DBG("wf: Registered sensor %s\n", new_sr->name);
wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_register_sensor);
void wf_unregister_sensor(struct wf_sensor *sr)
{
mutex_lock(&wf_lock);
list_del(&sr->link);
mutex_unlock(&wf_lock);
DBG("wf: Unregistered sensor %s\n", sr->name);
wf_put_sensor(sr);
}
EXPORT_SYMBOL_GPL(wf_unregister_sensor);
int wf_get_sensor(struct wf_sensor *sr)
{
if (!try_module_get(sr->ops->owner))
return -ENODEV;
kref_get(&sr->ref);
return 0;
}
EXPORT_SYMBOL_GPL(wf_get_sensor);
void wf_put_sensor(struct wf_sensor *sr)
{
struct module *mod = sr->ops->owner;
kref_put(&sr->ref, wf_sensor_release);
module_put(mod);
}
EXPORT_SYMBOL_GPL(wf_put_sensor);
/*
* Client & notification
*/
int wf_register_client(struct notifier_block *nb)
{
int rc;
struct wf_control *ct;
struct wf_sensor *sr;
mutex_lock(&wf_lock);
rc = blocking_notifier_chain_register(&wf_client_list, nb);
if (rc != 0)
goto bail;
wf_client_count++;
list_for_each_entry(ct, &wf_controls, link)
wf_notify(WF_EVENT_NEW_CONTROL, ct);
list_for_each_entry(sr, &wf_sensors, link)
wf_notify(WF_EVENT_NEW_SENSOR, sr);
if (wf_client_count == 1)
wf_start_thread();
bail:
mutex_unlock(&wf_lock);
return rc;
}
EXPORT_SYMBOL_GPL(wf_register_client);
int wf_unregister_client(struct notifier_block *nb)
{
mutex_lock(&wf_lock);
blocking_notifier_chain_unregister(&wf_client_list, nb);
wf_client_count--;
if (wf_client_count == 0)
wf_stop_thread();
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_unregister_client);
void wf_set_overtemp(void)
{
mutex_lock(&wf_lock);
wf_overtemp++;
if (wf_overtemp == 1) {
printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
wf_overtemp_counter = 0;
wf_notify(WF_EVENT_OVERTEMP, NULL);
}
mutex_unlock(&wf_lock);
}
EXPORT_SYMBOL_GPL(wf_set_overtemp);
void wf_clear_overtemp(void)
{
mutex_lock(&wf_lock);
WARN_ON(wf_overtemp == 0);
if (wf_overtemp == 0) {
mutex_unlock(&wf_lock);
return;
}
wf_overtemp--;
if (wf_overtemp == 0) {
printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
wf_notify(WF_EVENT_NORMALTEMP, NULL);
}
mutex_unlock(&wf_lock);
}
EXPORT_SYMBOL_GPL(wf_clear_overtemp);
static int __init windfarm_core_init(void)
{
DBG("wf: core loaded\n");
platform_device_register(&wf_platform_device);
return 0;
}
static void __exit windfarm_core_exit(void)
{
BUG_ON(wf_client_count != 0);
DBG("wf: core unloaded\n");
platform_device_unregister(&wf_platform_device);
}
module_init(windfarm_core_init);
module_exit(windfarm_core_exit);
MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("Core component of PowerMac thermal control");
MODULE_LICENSE("GPL");