windfarm_core.c

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/*
 * Windfarm PowerMac thermal control. Core
 *
 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
 *                    <[email protected]>
 *
 * 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);
}

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);
}
EXPORT_SYMBOL_GPL(wf_critical_overtemp);

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);

struct wf_control * wf_find_control(const char *name)
{
    struct wf_control *ct;

    mutex_lock(&wf_lock);
    list_for_each_entry(ct, &wf_controls, link) {
        if (!strcmp(ct->name, name)) {
            if (wf_get_control(ct))
                ct = NULL;
            mutex_unlock(&wf_lock);
            return ct;
        }
    }
    mutex_unlock(&wf_lock);
    return NULL;
}
EXPORT_SYMBOL_GPL(wf_find_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);

struct wf_sensor * wf_find_sensor(const char *name)
{
    struct wf_sensor *sr;

    mutex_lock(&wf_lock);
    list_for_each_entry(sr, &wf_sensors, link) {
        if (!strcmp(sr->name, name)) {
            if (wf_get_sensor(sr))
                sr = NULL;
            mutex_unlock(&wf_lock);
            return sr;
        }
    }
    mutex_unlock(&wf_lock);
    return NULL;
}
EXPORT_SYMBOL_GPL(wf_find_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);

int wf_is_overtemp(void)
{
    return (wf_overtemp != 0);
}
EXPORT_SYMBOL_GPL(wf_is_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 <[email protected]>");
MODULE_DESCRIPTION("Core component of PowerMac thermal control");
MODULE_LICENSE("GPL");