/*
   * 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);

  }
  
  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
  ");

  	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
  ");
  					machine_power_off();
  				}
  			}
  			next += HZ;
  		}
  
  		delay = next - jiffies;
  		if (delay <= HZ)
  			schedule_timeout_interruptible(delay);

  	}
  
  	DBG("wf: thread stopped
  ");
  
  	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
  ",
  		       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
  ", 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);
  	s32 val = 0;
  	int err;
  
  	err = ctrl->ops->get_value(ctrl, &val);
  	if (err < 0)
  		return err;
  	return sprintf(buf, "%d
  ", val);
  }
  
  /* 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 == '
  '))
  		++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
  ", 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
  ", new_ct->name);
  		/* the subsystem still does useful work without the file */

  	DBG("wf: Registered control %s
  ", 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
  ", 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
  ", 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
  ", 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
  ", 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
  ", new_sr->name);
  		/* the subsystem still does useful work without the file */

  	DBG("wf: Registered sensor %s
  ", 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
  ", 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 !
  ");
  		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 !
  ");
  		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
  ");

  	/* Don't register on old machines that use therm_pm72 for now */

  	if (of_machine_is_compatible("PowerMac7,2") ||
  	    of_machine_is_compatible("PowerMac7,3") ||
  	    of_machine_is_compatible("RackMac3,1"))

  		return -ENODEV;

  	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
  ");
  
  	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");