therm_pm72.c

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		start = jiffies;

		down(&driver_lock);

		/* Tickle the FCU just in case */
		if (--fcu_tickle_ticks < 0) {
			fcu_tickle_ticks = FCU_TICKLE_TICKS;
			tickle_fcu();
		}

		/* First, we always calculate the new DIMMs state on an Xserve */
		if (rackmac)
			do_monitor_dimms(&dimms_state);

		/* Then, the CPUs */
		if (cpu_pid_type == CPU_PID_TYPE_COMBINED)
			do_monitor_cpu_combined();
		else if (cpu_pid_type == CPU_PID_TYPE_RACKMAC) {
			do_monitor_cpu_rack(&cpu_state[0]);
			if (cpu_state[1].monitor != NULL)
				do_monitor_cpu_rack(&cpu_state[1]);
			// better deal with UP
		} else {
			do_monitor_cpu_split(&cpu_state[0]);
			if (cpu_state[1].monitor != NULL)
				do_monitor_cpu_split(&cpu_state[1]);
			// better deal with UP
		}
		/* Then, the rest */
		do_monitor_backside(&backside_state);
		if (rackmac)
			do_monitor_slots(&slots_state);
		else
			do_monitor_drives(&drives_state);
		up(&driver_lock);

		if (critical_state == 1) {
			printk(KERN_WARNING "Temperature control detected a critical condition\n");
			printk(KERN_WARNING "Attempting to shut down...\n");
			if (call_critical_overtemp()) {
				printk(KERN_WARNING "Can't call %s, power off now!\n",
				       critical_overtemp_path);
				machine_power_off();
			}
		}
		if (critical_state > 0)
			critical_state++;
		if (critical_state > MAX_CRITICAL_STATE) {
			printk(KERN_WARNING "Shutdown timed out, power off now !\n");
			machine_power_off();
		}

		// FIXME: Deal with signals
		elapsed = jiffies - start;
		if (elapsed < HZ)
			schedule_timeout_interruptible(HZ - elapsed);
	}

 out:
	DBG("main_control_loop ended\n");

	ctrl_task = 0;
	complete_and_exit(&ctrl_complete, 0);
}

/*
 * Dispose the control loops when tearing down
 */
static void dispose_control_loops(void)
{
	dispose_cpu_state(&cpu_state[0]);
	dispose_cpu_state(&cpu_state[1]);
	dispose_backside_state(&backside_state);
	dispose_drives_state(&drives_state);
	dispose_slots_state(&slots_state);
	dispose_dimms_state(&dimms_state);
}

/*
 * Create the control loops. U3-0 i2c bus is up, so we can now
 * get to the various sensors
 */
static int create_control_loops(void)
{
	struct device_node *np;

	/* Count CPUs from the device-tree, we don't care how many are
	 * actually used by Linux
	 */
	cpu_count = 0;
	for (np = NULL; NULL != (np = of_find_node_by_type(np, "cpu"));)
		cpu_count++;

	DBG("counted %d CPUs in the device-tree\n", cpu_count);

	/* Decide the type of PID algorithm to use based on the presence of
	 * the pumps, though that may not be the best way, that is good enough
	 * for now
	 */
	if (rackmac)
		cpu_pid_type = CPU_PID_TYPE_RACKMAC;
	else if (machine_is_compatible("PowerMac7,3")
	    && (cpu_count > 1)
	    && fcu_fans[CPUA_PUMP_RPM_INDEX].id != FCU_FAN_ABSENT_ID
	    && fcu_fans[CPUB_PUMP_RPM_INDEX].id != FCU_FAN_ABSENT_ID) {
		printk(KERN_INFO "Liquid cooling pumps detected, using new algorithm !\n");
		cpu_pid_type = CPU_PID_TYPE_COMBINED;
	} else
		cpu_pid_type = CPU_PID_TYPE_SPLIT;

	/* Create control loops for everything. If any fail, everything
	 * fails
	 */
	if (init_cpu_state(&cpu_state[0], 0))
		goto fail;
	if (cpu_pid_type == CPU_PID_TYPE_COMBINED)
		fetch_cpu_pumps_minmax();

	if (cpu_count > 1 && init_cpu_state(&cpu_state[1], 1))
		goto fail;
	if (init_backside_state(&backside_state))
		goto fail;
	if (rackmac && init_dimms_state(&dimms_state))
		goto fail;
	if (rackmac && init_slots_state(&slots_state))
		goto fail;
	if (!rackmac && init_drives_state(&drives_state))
		goto fail;

	DBG("all control loops up !\n");

	return 0;
	
 fail:
	DBG("failure creating control loops, disposing\n");

	dispose_control_loops();

	return -ENODEV;
}

/*
 * Start the control loops after everything is up, that is create
 * the thread that will make them run
 */
static void start_control_loops(void)
{
	init_completion(&ctrl_complete);

	ctrl_task = kernel_thread(main_control_loop, NULL, SIGCHLD | CLONE_KERNEL);
}

/*
 * Stop the control loops when tearing down
 */
static void stop_control_loops(void)
{
	if (ctrl_task != 0)
		wait_for_completion(&ctrl_complete);
}

/*
 * Attach to the i2c FCU after detecting U3-1 bus
 */
static int attach_fcu(void)
{
	fcu = attach_i2c_chip(FAN_CTRLER_ID, "fcu");
	if (fcu == NULL)
		return -ENODEV;

	DBG("FCU attached\n");

	return 0;
}

/*
 * Detach from the i2c FCU when tearing down
 */
static void detach_fcu(void)
{
	if (fcu)
		detach_i2c_chip(fcu);
	fcu = NULL;
}

/*
 * Attach to the i2c controller. We probe the various chips based
 * on the device-tree nodes and build everything for the driver to
 * run, we then kick the driver monitoring thread
 */
static int therm_pm72_attach(struct i2c_adapter *adapter)
{
	down(&driver_lock);

	/* Check state */
	if (state == state_detached)
		state = state_attaching;
	if (state != state_attaching) {
		up(&driver_lock);
		return 0;
	}

	/* Check if we are looking for one of these */
	if (u3_0 == NULL && !strcmp(adapter->name, "u3 0")) {
		u3_0 = adapter;
		DBG("found U3-0\n");
		if (k2 || !rackmac)
			if (create_control_loops())
				u3_0 = NULL;
	} else if (u3_1 == NULL && !strcmp(adapter->name, "u3 1")) {
		u3_1 = adapter;
		DBG("found U3-1, attaching FCU\n");
		if (attach_fcu())
			u3_1 = NULL;
	} else if (k2 == NULL && !strcmp(adapter->name, "mac-io 0")) {
		k2 = adapter;
		DBG("Found K2\n");
		if (u3_0 && rackmac)
			if (create_control_loops())
				k2 = NULL;
	}
	/* We got all we need, start control loops */
	if (u3_0 != NULL && u3_1 != NULL && (k2 || !rackmac)) {
		DBG("everything up, starting control loops\n");
		state = state_attached;
		start_control_loops();
	}
	up(&driver_lock);

	return 0;
}

/*
 * Called on every adapter when the driver or the i2c controller
 * is going away.
 */
static int therm_pm72_detach(struct i2c_adapter *adapter)
{
	down(&driver_lock);

	if (state != state_detached)
		state = state_detaching;

	/* Stop control loops if any */
	DBG("stopping control loops\n");
	up(&driver_lock);
	stop_control_loops();
	down(&driver_lock);

	if (u3_0 != NULL && !strcmp(adapter->name, "u3 0")) {
		DBG("lost U3-0, disposing control loops\n");
		dispose_control_loops();
		u3_0 = NULL;
	}
	
	if (u3_1 != NULL && !strcmp(adapter->name, "u3 1")) {
		DBG("lost U3-1, detaching FCU\n");
		detach_fcu();
		u3_1 = NULL;
	}
	if (u3_0 == NULL && u3_1 == NULL)
		state = state_detached;

	up(&driver_lock);

	return 0;
}

static int fan_check_loc_match(const char *loc, int fan)
{
	char	tmp[64];
	char	*c, *e;

	strlcpy(tmp, fcu_fans[fan].loc, 64);

	c = tmp;
	for (;;) {
		e = strchr(c, ',');
		if (e)
			*e = 0;
		if (strcmp(loc, c) == 0)
			return 1;
		if (e == NULL)
			break;
		c = e + 1;
	}
	return 0;
}

static void fcu_lookup_fans(struct device_node *fcu_node)
{
	struct device_node *np = NULL;
	int i;

	/* The table is filled by default with values that are suitable
	 * for the old machines without device-tree informations. We scan
	 * the device-tree and override those values with whatever is
	 * there
	 */

	DBG("Looking up FCU controls in device-tree...\n");

	while ((np = of_get_next_child(fcu_node, np)) != NULL) {
		int type = -1;
		const char *loc;
		const u32 *reg;

		DBG(" control: %s, type: %s\n", np->name, np->type);

		/* Detect control type */
		if (!strcmp(np->type, "fan-rpm-control") ||
		    !strcmp(np->type, "fan-rpm"))
			type = FCU_FAN_RPM;
		if (!strcmp(np->type, "fan-pwm-control") ||
		    !strcmp(np->type, "fan-pwm"))
			type = FCU_FAN_PWM;
		/* Only care about fans for now */
		if (type == -1)
			continue;

		/* Lookup for a matching location */
		loc = of_get_property(np, "location", NULL);
		reg = of_get_property(np, "reg", NULL);
		if (loc == NULL || reg == NULL)
			continue;
		DBG(" matching location: %s, reg: 0x%08x\n", loc, *reg);

		for (i = 0; i < FCU_FAN_COUNT; i++) {
			int fan_id;

			if (!fan_check_loc_match(loc, i))
				continue;
			DBG(" location match, index: %d\n", i);
			fcu_fans[i].id = FCU_FAN_ABSENT_ID;
			if (type != fcu_fans[i].type) {
				printk(KERN_WARNING "therm_pm72: Fan type mismatch "
				       "in device-tree for %s\n", np->full_name);
				break;
			}
			if (type == FCU_FAN_RPM)
				fan_id = ((*reg) - 0x10) / 2;
			else
				fan_id = ((*reg) - 0x30) / 2;
			if (fan_id > 7) {
				printk(KERN_WARNING "therm_pm72: Can't parse "
				       "fan ID in device-tree for %s\n", np->full_name);
				break;
			}
			DBG(" fan id -> %d, type -> %d\n", fan_id, type);
			fcu_fans[i].id = fan_id;
		}
	}

	/* Now dump the array */
	printk(KERN_INFO "Detected fan controls:\n");
	for (i = 0; i < FCU_FAN_COUNT; i++) {
		if (fcu_fans[i].id == FCU_FAN_ABSENT_ID)
			continue;
		printk(KERN_INFO "  %d: %s fan, id %d, location: %s\n", i,
		       fcu_fans[i].type == FCU_FAN_RPM ? "RPM" : "PWM",
		       fcu_fans[i].id, fcu_fans[i].loc);
	}
}

static int fcu_of_probe(struct of_device* dev, const struct of_device_id *match)
{
	state = state_detached;

	/* Lookup the fans in the device tree */
	fcu_lookup_fans(dev->node);

	/* Add the driver */
	return i2c_add_driver(&therm_pm72_driver);
}

static int fcu_of_remove(struct of_device* dev)
{
	i2c_del_driver(&therm_pm72_driver);

	return 0;
}

static struct of_device_id fcu_match[] = 
{
	{
	.type		= "fcu",
	},
	{},
};

static struct of_platform_driver fcu_of_platform_driver = 
{
	.name 		= "temperature",
	.match_table	= fcu_match,
	.probe		= fcu_of_probe,
	.remove		= fcu_of_remove
};

/*
 * Check machine type, attach to i2c controller
 */
static int __init therm_pm72_init(void)
{
	struct device_node *np;

	rackmac = machine_is_compatible("RackMac3,1");

	if (!machine_is_compatible("PowerMac7,2") &&
	    !machine_is_compatible("PowerMac7,3") &&
	    !rackmac)
	    	return -ENODEV;

	printk(KERN_INFO "PowerMac G5 Thermal control driver %s\n", VERSION);

	np = of_find_node_by_type(NULL, "fcu");
	if (np == NULL) {
		/* Some machines have strangely broken device-tree */
		np = of_find_node_by_path("/u3@0,f8000000/i2c@f8001000/fan@15e");
		if (np == NULL) {
			    printk(KERN_ERR "Can't find FCU in device-tree !\n");
			    return -ENODEV;
		}
	}
	of_dev = of_platform_device_create(np, "temperature", NULL);
	if (of_dev == NULL) {
		printk(KERN_ERR "Can't register FCU platform device !\n");
		return -ENODEV;
	}

	of_register_platform_driver(&fcu_of_platform_driver);
	
	return 0;
}

static void __exit therm_pm72_exit(void)
{
	of_unregister_platform_driver(&fcu_of_platform_driver);

	if (of_dev)
		of_device_unregister(of_dev);
}

module_init(therm_pm72_init);
module_exit(therm_pm72_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <[e-mail]>");
MODULE_DESCRIPTION("Driver for Apple's PowerMac G5 thermal control");
MODULE_LICENSE("GPL");