[PATCH] powerpc: Thermal control for dual core G5s

This patch adds a windfarm module, windfarm_pm112, for the dual core G5s
(both 2 and 4 core models), keeping the machine from getting into
vacuum-cleaner mode ;) For proper credits, the patch was initially
written by Paul Mackerras, and slightly reworked by me to add overtemp
handling among others. The patch also removes the sysfs attributes from
windfarm_pm81 and windfarm_pm91 and instead adds code to the windfarm
core to automagically expose attributes for sensor & controls.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 698 insertions, 0 deletions

diff --git a/drivers/macintosh/windfarm_pm112.c b/drivers/macintosh/windfarm_pm112.c
new file mode 100644
index 0000000..c2a4e68
--- /dev/null
+++ b/drivers/macintosh/windfarm_pm112.c
@@ -0,0 +1,698 @@
+/*
+ * Windfarm PowerMac thermal control.
+ * Control loops for machines with SMU and PPC970MP processors.
+ *
+ * Copyright (C) 2005 Paul Mackerras, IBM Corp. <paulus@samba.org>
+ * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corp.
+ *
+ * Use and redistribute under the terms of the GNU GPL v2.
+ */
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <asm/prom.h>
+#include <asm/smu.h>
+
+#include "windfarm.h"
+#include "windfarm_pid.h"
+
+#define VERSION "0.2"
+
+#define DEBUG
+#undef LOTSA_DEBUG
+
+#ifdef DEBUG
+#define DBG(args...)	printk(args)
+#else
+#define DBG(args...)	do { } while(0)
+#endif
+
+#ifdef LOTSA_DEBUG
+#define DBG_LOTS(args...)	printk(args)
+#else
+#define DBG_LOTS(args...)	do { } while(0)
+#endif
+
+/* define this to force CPU overtemp to 60 degree, useful for testing
+ * the overtemp code
+ */
+#undef HACKED_OVERTEMP
+
+/* We currently only handle 2 chips, 4 cores... */
+#define NR_CHIPS	2
+#define NR_CORES	4
+#define NR_CPU_FANS	3 * NR_CHIPS
+
+/* Controls and sensors */
+static struct wf_sensor *sens_cpu_temp[NR_CORES];
+static struct wf_sensor *sens_cpu_power[NR_CORES];
+static struct wf_sensor *hd_temp;
+static struct wf_sensor *slots_power;
+static struct wf_sensor *u4_temp;
+
+static struct wf_control *cpu_fans[NR_CPU_FANS];
+static char *cpu_fan_names[NR_CPU_FANS] = {
+	"cpu-rear-fan-0",
+	"cpu-rear-fan-1",
+	"cpu-front-fan-0",
+	"cpu-front-fan-1",
+	"cpu-pump-0",
+	"cpu-pump-1",
+};
+static struct wf_control *cpufreq_clamp;
+
+/* Second pump isn't required (and isn't actually present) */
+#define CPU_FANS_REQD		(NR_CPU_FANS - 2)
+#define FIRST_PUMP		4
+#define LAST_PUMP		5
+
+/* We keep a temperature history for average calculation of 180s */
+#define CPU_TEMP_HIST_SIZE	180
+
+/* Scale factor for fan speed, *100 */
+static int cpu_fan_scale[NR_CPU_FANS] = {
+	100,
+	100,
+	97,		/* inlet fans run at 97% of exhaust fan */
+	97,
+	100,		/* updated later */
+	100,		/* updated later */
+};
+
+static struct wf_control *backside_fan;
+static struct wf_control *slots_fan;
+static struct wf_control *drive_bay_fan;
+
+/* PID loop state */
+static struct wf_cpu_pid_state cpu_pid[NR_CORES];
+static u32 cpu_thist[CPU_TEMP_HIST_SIZE];
+static int cpu_thist_pt;
+static s64 cpu_thist_total;
+static s32 cpu_all_tmax = 100 << 16;
+static int cpu_last_target;
+static struct wf_pid_state backside_pid;
+static int backside_tick;
+static struct wf_pid_state slots_pid;
+static int slots_started;
+static struct wf_pid_state drive_bay_pid;
+static int drive_bay_tick;
+
+static int nr_cores;
+static int have_all_controls;
+static int have_all_sensors;
+static int started;
+
+static int failure_state;
+#define FAILURE_SENSOR		1
+#define FAILURE_FAN		2
+#define FAILURE_PERM		4
+#define FAILURE_LOW_OVERTEMP	8
+#define FAILURE_HIGH_OVERTEMP	16
+
+/* Overtemp values */
+#define LOW_OVER_AVERAGE	0
+#define LOW_OVER_IMMEDIATE	(10 << 16)
+#define LOW_OVER_CLEAR		((-10) << 16)
+#define HIGH_OVER_IMMEDIATE	(14 << 16)
+#define HIGH_OVER_AVERAGE	(10 << 16)
+#define HIGH_OVER_IMMEDIATE	(14 << 16)
+
+
+/* Implementation... */
+static int create_cpu_loop(int cpu)
+{
+	int chip = cpu / 2;
+	int core = cpu & 1;
+	struct smu_sdbp_header *hdr;
+	struct smu_sdbp_cpupiddata *piddata;
+	struct wf_cpu_pid_param pid;
+	struct wf_control *main_fan = cpu_fans[0];
+	s32 tmax;
+	int fmin;
+
+	/* Get PID params from the appropriate SAT */
+	hdr = smu_sat_get_sdb_partition(chip, 0xC8 + core, NULL);
+	if (hdr == NULL) {
+		printk(KERN_WARNING"windfarm: can't get CPU PID fan config\n");
+		return -EINVAL;
+	}
+	piddata = (struct smu_sdbp_cpupiddata *)&hdr[1];
+
+	/* Get FVT params to get Tmax; if not found, assume default */
+	hdr = smu_sat_get_sdb_partition(chip, 0xC4 + core, NULL);
+	if (hdr) {
+		struct smu_sdbp_fvt *fvt = (struct smu_sdbp_fvt *)&hdr[1];
+		tmax = fvt->maxtemp << 16;
+	} else
+		tmax = 95 << 16;	/* default to 95 degrees C */
+
+	/* We keep a global tmax for overtemp calculations */
+	if (tmax < cpu_all_tmax)
+		cpu_all_tmax = tmax;
+
+	/*
+	 * Darwin has a minimum fan speed of 1000 rpm for the 4-way and
+	 * 515 for the 2-way.  That appears to be overkill, so for now,
+	 * impose a minimum of 750 or 515.
+	 */
+	fmin = (nr_cores > 2) ? 750 : 515;
+
+	/* Initialize PID loop */
+	pid.interval = 1;	/* seconds */
+	pid.history_len = piddata->history_len;
+	pid.gd = piddata->gd;
+	pid.gp = piddata->gp;
+	pid.gr = piddata->gr / piddata->history_len;
+	pid.pmaxadj = (piddata->max_power << 16) - (piddata->power_adj << 8);
+	pid.ttarget = tmax - (piddata->target_temp_delta << 16);
+	pid.tmax = tmax;
+	pid.min = main_fan->ops->get_min(main_fan);
+	pid.max = main_fan->ops->get_max(main_fan);
+	if (pid.min < fmin)
+		pid.min = fmin;
+
+	wf_cpu_pid_init(&cpu_pid[cpu], &pid);
+	return 0;
+}
+
+static void cpu_max_all_fans(void)
+{
+	int i;
+
+	/* We max all CPU fans in case of a sensor error. We also do the
+	 * cpufreq clamping now, even if it's supposedly done later by the
+	 * generic code anyway, we do it earlier here to react faster
+	 */
+	if (cpufreq_clamp)
+		wf_control_set_max(cpufreq_clamp);
+	for (i = 0; i < NR_CPU_FANS; ++i)
+		if (cpu_fans[i])
+			wf_control_set_max(cpu_fans[i]);
+}
+
+static int cpu_check_overtemp(s32 temp)
+{
+	int new_state = 0;
+	s32 t_avg, t_old;
+
+	/* First check for immediate overtemps */
+	if (temp >= (cpu_all_tmax + LOW_OVER_IMMEDIATE)) {
+		new_state |= FAILURE_LOW_OVERTEMP;
+		if ((failure_state & FAILURE_LOW_OVERTEMP) == 0)
+			printk(KERN_ERR "windfarm: Overtemp due to immediate CPU"
+			       " temperature !\n");
+	}
+	if (temp >= (cpu_all_tmax + HIGH_OVER_IMMEDIATE)) {
+		new_state |= FAILURE_HIGH_OVERTEMP;
+		if ((failure_state & FAILURE_HIGH_OVERTEMP) == 0)
+			printk(KERN_ERR "windfarm: Critical overtemp due to"
+			       " immediate CPU temperature !\n");
+	}
+
+	/* We calculate a history of max temperatures and use that for the
+	 * overtemp management
+	 */
+	t_old = cpu_thist[cpu_thist_pt];
+	cpu_thist[cpu_thist_pt] = temp;
+	cpu_thist_pt = (cpu_thist_pt + 1) % CPU_TEMP_HIST_SIZE;
+	cpu_thist_total -= t_old;
+	cpu_thist_total += temp;
+	t_avg = cpu_thist_total / CPU_TEMP_HIST_SIZE;
+
+	DBG_LOTS("t_avg = %d.%03d (out: %d.%03d, in: %d.%03d)\n",
+		 FIX32TOPRINT(t_avg), FIX32TOPRINT(t_old), FIX32TOPRINT(temp));
+
+	/* Now check for average overtemps */
+	if (t_avg >= (cpu_all_tmax + LOW_OVER_AVERAGE)) {
+		new_state |= FAILURE_LOW_OVERTEMP;
+		if ((failure_state & FAILURE_LOW_OVERTEMP) == 0)
+			printk(KERN_ERR "windfarm: Overtemp due to average CPU"
+			       " temperature !\n");
+	}
+	if (t_avg >= (cpu_all_tmax + HIGH_OVER_AVERAGE)) {
+		new_state |= FAILURE_HIGH_OVERTEMP;
+		if ((failure_state & FAILURE_HIGH_OVERTEMP) == 0)
+			printk(KERN_ERR "windfarm: Critical overtemp due to"
+			       " average CPU temperature !\n");
+	}
+
+	/* Now handle overtemp conditions. We don't currently use the windfarm
+	 * overtemp handling core as it's not fully suited to the needs of those
+	 * new machine. This will be fixed later.
+	 */
+	if (new_state) {
+		/* High overtemp -> immediate shutdown */
+		if (new_state & FAILURE_HIGH_OVERTEMP)
+			machine_power_off();
+		if ((failure_state & new_state) != new_state)
+			cpu_max_all_fans();
+		failure_state |= new_state;
+	} else if ((failure_state & FAILURE_LOW_OVERTEMP) &&
+		   (temp < (cpu_all_tmax + LOW_OVER_CLEAR))) {
+		printk(KERN_ERR "windfarm: Overtemp condition cleared !\n");
+		failure_state &= ~FAILURE_LOW_OVERTEMP;
+	}
+
+	return failure_state & (FAILURE_LOW_OVERTEMP | FAILURE_HIGH_OVERTEMP);
+}
+
+static void cpu_fans_tick(void)
+{
+	int err, cpu;
+	s32 greatest_delta = 0;
+	s32 temp, power, t_max = 0;
+	int i, t, target = 0;
+	struct wf_sensor *sr;
+	struct wf_control *ct;
+	struct wf_cpu_pid_state *sp;
+
+	DBG_LOTS(KERN_DEBUG);
+	for (cpu = 0; cpu < nr_cores; ++cpu) {
+		/* Get CPU core temperature */
+		sr = sens_cpu_temp[cpu];
+		err = sr->ops->get_value(sr, &temp);
+		if (err) {
+			DBG("\n");
+			printk(KERN_WARNING "windfarm: CPU %d temperature "
+			       "sensor error %d\n", cpu, err);
+			failure_state |= FAILURE_SENSOR;
+			cpu_max_all_fans();
+			return;
+		}
+
+		/* Keep track of highest temp */
+		t_max = max(t_max, temp);
+
+		/* Get CPU power */
+		sr = sens_cpu_power[cpu];
+		err = sr->ops->get_value(sr, &power);
+		if (err) {
+			DBG("\n");
+			printk(KERN_WARNING "windfarm: CPU %d power "
+			       "sensor error %d\n", cpu, err);
+			failure_state |= FAILURE_SENSOR;
+			cpu_max_all_fans();
+			return;
+		}
+
+		/* Run PID */
+		sp = &cpu_pid[cpu];
+		t = wf_cpu_pid_run(sp, power, temp);
+
+		if (cpu == 0 || sp->last_delta > greatest_delta) {
+			greatest_delta = sp->last_delta;
+			target = t;
+		}
+		DBG_LOTS("[%d] P=%d.%.3d T=%d.%.3d ",
+		    cpu, FIX32TOPRINT(power), FIX32TOPRINT(temp));
+	}
+	DBG_LOTS("fans = %d, t_max = %d.%03d\n", target, FIX32TOPRINT(t_max));
+
+	/* Darwin limits decrease to 20 per iteration */
+	if (target < (cpu_last_target - 20))
+		target = cpu_last_target - 20;
+	cpu_last_target = target;
+	for (cpu = 0; cpu < nr_cores; ++cpu)
+		cpu_pid[cpu].target = target;
+
+	/* Handle possible overtemps */
+	if (cpu_check_overtemp(t_max))
+		return;
+
+	/* Set fans */
+	for (i = 0; i < NR_CPU_FANS; ++i) {
+		ct = cpu_fans[i];
+		if (ct == NULL)
+			continue;
+		err = ct->ops->set_value(ct, target * cpu_fan_scale[i] / 100);
+		if (err) {
+			printk(KERN_WARNING "windfarm: fan %s reports "
+			       "error %d\n", ct->name, err);
+			failure_state |= FAILURE_FAN;
+			break;
+		}
+	}
+}
+
+/* Backside/U4 fan */
+static struct wf_pid_param backside_param = {
+	.interval	= 5,
+	.history_len	= 2,
+	.gd		= 48 << 20,
+	.gp		= 5 << 20,
+	.gr		= 0,
+	.itarget	= 64 << 16,
+	.additive	= 1,
+};
+
+static void backside_fan_tick(void)
+{
+	s32 temp;
+	int speed;
+	int err;
+
+	if (!backside_fan || !u4_temp)
+		return;
+	if (!backside_tick) {
+		/* first time; initialize things */
+		backside_param.min = backside_fan->ops->get_min(backside_fan);
+		backside_param.max = backside_fan->ops->get_max(backside_fan);
+		wf_pid_init(&backside_pid, &backside_param);
+		backside_tick = 1;
+	}
+	if (--backside_tick > 0)
+		return;
+	backside_tick = backside_pid.param.interval;
+
+	err = u4_temp->ops->get_value(u4_temp, &temp);
+	if (err) {
+		printk(KERN_WARNING "windfarm: U4 temp sensor error %d\n",
+		       err);
+		failure_state |= FAILURE_SENSOR;
+		wf_control_set_max(backside_fan);
+		return;
+	}
+	speed = wf_pid_run(&backside_pid, temp);
+	DBG_LOTS("backside PID temp=%d.%.3d speed=%d\n",
+		 FIX32TOPRINT(temp), speed);
+
+	err = backside_fan->ops->set_value(backside_fan, speed);
+	if (err) {
+		printk(KERN_WARNING "windfarm: backside fan error %d\n", err);
+		failure_state |= FAILURE_FAN;
+	}
+}
+
+/* Drive bay fan */
+static struct wf_pid_param drive_bay_prm = {
+	.interval	= 5,
+	.history_len	= 2,
+	.gd		= 30 << 20,
+	.gp		= 5 << 20,
+	.gr		= 0,
+	.itarget	= 40 << 16,
+	.additive	= 1,
+};
+
+static void drive_bay_fan_tick(void)
+{
+	s32 temp;
+	int speed;
+	int err;
+
+	if (!drive_bay_fan || !hd_temp)
+		return;
+	if (!drive_bay_tick) {
+		/* first time; initialize things */
+		drive_bay_prm.min = drive_bay_fan->ops->get_min(drive_bay_fan);
+		drive_bay_prm.max = drive_bay_fan->ops->get_max(drive_bay_fan);
+		wf_pid_init(&drive_bay_pid, &drive_bay_prm);
+		drive_bay_tick = 1;
+	}
+	if (--drive_bay_tick > 0)
+		return;
+	drive_bay_tick = drive_bay_pid.param.interval;
+
+	err = hd_temp->ops->get_value(hd_temp, &temp);
+	if (err) {
+		printk(KERN_WARNING "windfarm: drive bay temp sensor "
+		       "error %d\n", err);
+		failure_state |= FAILURE_SENSOR;
+		wf_control_set_max(drive_bay_fan);
+		return;
+	}
+	speed = wf_pid_run(&drive_bay_pid, temp);
+	DBG_LOTS("drive_bay PID temp=%d.%.3d speed=%d\n",
+		 FIX32TOPRINT(temp), speed);
+
+	err = drive_bay_fan->ops->set_value(drive_bay_fan, speed);
+	if (err) {
+		printk(KERN_WARNING "windfarm: drive bay fan error %d\n", err);
+		failure_state |= FAILURE_FAN;
+	}
+}
+
+/* PCI slots area fan */
+/* This makes the fan speed proportional to the power consumed */
+static struct wf_pid_param slots_param = {
+	.interval	= 1,
+	.history_len	= 2,
+	.gd		= 0,
+	.gp		= 0,
+	.gr		= 0x1277952,
+	.itarget	= 0,
+	.min		= 1560,
+	.max		= 3510,
+};
+
+static void slots_fan_tick(void)
+{
+	s32 power;
+	int speed;
+	int err;
+
+	if (!slots_fan || !slots_power)
+		return;
+	if (!slots_started) {
+		/* first time; initialize things */
+		wf_pid_init(&slots_pid, &slots_param);
+		slots_started = 1;
+	}
+
+	err = slots_power->ops->get_value(slots_power, &power);
+	if (err) {
+		printk(KERN_WARNING "windfarm: slots power sensor error %d\n",
+		       err);
+		failure_state |= FAILURE_SENSOR;
+		wf_control_set_max(slots_fan);
+		return;
+	}
+	speed = wf_pid_run(&slots_pid, power);
+	DBG_LOTS("slots PID power=%d.%.3d speed=%d\n",
+		 FIX32TOPRINT(power), speed);
+
+	err = slots_fan->ops->set_value(slots_fan, speed);
+	if (err) {
+		printk(KERN_WARNING "windfarm: slots fan error %d\n", err);
+		failure_state |= FAILURE_FAN;
+	}
+}
+
+static void set_fail_state(void)
+{
+	int i;
+
+	if (cpufreq_clamp)
+		wf_control_set_max(cpufreq_clamp);
+	for (i = 0; i < NR_CPU_FANS; ++i)
+		if (cpu_fans[i])
+			wf_control_set_max(cpu_fans[i]);
+	if (backside_fan)
+		wf_control_set_max(backside_fan);
+	if (slots_fan)
+		wf_control_set_max(slots_fan);
+	if (drive_bay_fan)
+		wf_control_set_max(drive_bay_fan);
+}
+
+static void pm112_tick(void)
+{
+	int i, last_failure;
+
+	if (!started) {
+		started = 1;
+		for (i = 0; i < nr_cores; ++i) {
+			if (create_cpu_loop(i) < 0) {
+				failure_state = FAILURE_PERM;
+				set_fail_state();
+				break;
+			}
+		}
+		DBG_LOTS("cpu_all_tmax=%d.%03d\n", FIX32TOPRINT(cpu_all_tmax));
+
+#ifdef HACKED_OVERTEMP
+		cpu_all_tmax = 60 << 16;
+#endif
+	}
+
+	/* Permanent failure, bail out */
+	if (failure_state & FAILURE_PERM)
+		return;
+	/* Clear all failure bits except low overtemp which will be eventually
+	 * cleared by the control loop itself
+	 */
+	last_failure = failure_state;
+	failure_state &= FAILURE_LOW_OVERTEMP;
+	cpu_fans_tick();
+	backside_fan_tick();
+	slots_fan_tick();
+	drive_bay_fan_tick();
+
+	DBG_LOTS("last_failure: 0x%x, failure_state: %x\n",
+		 last_failure, failure_state);
+
+	/* Check for failures. Any failure causes cpufreq clamping */
+	if (failure_state && last_failure == 0 && cpufreq_clamp)
+		wf_control_set_max(cpufreq_clamp);
+	if (failure_state == 0 && last_failure && cpufreq_clamp)
+		wf_control_set_min(cpufreq_clamp);
+
+	/* That's it for now, we might want to deal with other failures
+	 * differently in the future though
+	 */
+}
+
+static void pm112_new_control(struct wf_control *ct)
+{
+	int i, max_exhaust;
+
+	if (cpufreq_clamp == NULL && !strcmp(ct->name, "cpufreq-clamp")) {
+		if (wf_get_control(ct) == 0)
+			cpufreq_clamp = ct;
+	}
+
+	for (i = 0; i < NR_CPU_FANS; ++i) {
+		if (!strcmp(ct->name, cpu_fan_names[i])) {
+			if (cpu_fans[i] == NULL && wf_get_control(ct) == 0)
+				cpu_fans[i] = ct;
+			break;
+		}
+	}
+	if (i >= NR_CPU_FANS) {
+		/* not a CPU fan, try the others */
+		if (!strcmp(ct->name, "backside-fan")) {
+			if (backside_fan == NULL && wf_get_control(ct) == 0)
+				backside_fan = ct;
+		} else if (!strcmp(ct->name, "slots-fan")) {
+			if (slots_fan == NULL && wf_get_control(ct) == 0)
+				slots_fan = ct;
+		} else if (!strcmp(ct->name, "drive-bay-fan")) {
+			if (drive_bay_fan == NULL && wf_get_control(ct) == 0)
+				drive_bay_fan = ct;
+		}
+		return;
+	}
+
+	for (i = 0; i < CPU_FANS_REQD; ++i)
+		if (cpu_fans[i] == NULL)
+			return;
+
+	/* work out pump scaling factors */
+	max_exhaust = cpu_fans[0]->ops->get_max(cpu_fans[0]);
+	for (i = FIRST_PUMP; i <= LAST_PUMP; ++i)
+		if ((ct = cpu_fans[i]) != NULL)
+			cpu_fan_scale[i] =
+				ct->ops->get_max(ct) * 100 / max_exhaust;
+
+	have_all_controls = 1;
+}
+
+static void pm112_new_sensor(struct wf_sensor *sr)
+{
+	unsigned int i;
+
+	if (have_all_sensors)
+		return;
+	if (!strncmp(sr->name, "cpu-temp-", 9)) {
+		i = sr->name[9] - '0';
+		if (sr->name[10] == 0 && i < NR_CORES &&
+		    sens_cpu_temp[i] == NULL && wf_get_sensor(sr) == 0)
+			sens_cpu_temp[i] = sr;
+
+	} else if (!strncmp(sr->name, "cpu-power-", 10)) {
+		i = sr->name[10] - '0';
+		if (sr->name[11] == 0 && i < NR_CORES &&
+		    sens_cpu_power[i] == NULL && wf_get_sensor(sr) == 0)
+			sens_cpu_power[i] = sr;
+	} else if (!strcmp(sr->name, "hd-temp")) {
+		if (hd_temp == NULL && wf_get_sensor(sr) == 0)
+			hd_temp = sr;
+	} else if (!strcmp(sr->name, "slots-power")) {
+		if (slots_power == NULL && wf_get_sensor(sr) == 0)
+			slots_power = sr;
+	} else if (!strcmp(sr->name, "u4-temp")) {
+		if (u4_temp == NULL && wf_get_sensor(sr) == 0)
+			u4_temp = sr;
+	} else
+		return;
+
+	/* check if we have all the sensors we need */
+	for (i = 0; i < nr_cores; ++i)
+		if (sens_cpu_temp[i] == NULL || sens_cpu_power[i] == NULL)
+			return;
+
+	have_all_sensors = 1;
+}
+
+static int pm112_wf_notify(struct notifier_block *self,
+			   unsigned long event, void *data)
+{
+	switch (event) {
+	case WF_EVENT_NEW_SENSOR:
+		pm112_new_sensor(data);
+		break;
+	case WF_EVENT_NEW_CONTROL:
+		pm112_new_control(data);
+		break;
+	case WF_EVENT_TICK:
+		if (have_all_controls && have_all_sensors)
+			pm112_tick();
+	}
+	return 0;
+}
+
+static struct notifier_block pm112_events = {
+	.notifier_call = pm112_wf_notify,
+};
+
+static int wf_pm112_probe(struct device *dev)
+{
+	wf_register_client(&pm112_events);
+	return 0;
+}
+
+static int wf_pm112_remove(struct device *dev)
+{
+	wf_unregister_client(&pm112_events);
+	/* should release all sensors and controls */
+	return 0;
+}
+
+static struct device_driver wf_pm112_driver = {
+	.name = "windfarm",
+	.bus = &platform_bus_type,
+	.probe = wf_pm112_probe,
+	.remove = wf_pm112_remove,
+};
+
+static int __init wf_pm112_init(void)
+{
+	struct device_node *cpu;
+
+	if (!machine_is_compatible("PowerMac11,2"))
+		return -ENODEV;
+
+	/* Count the number of CPU cores */
+	nr_cores = 0;
+	for (cpu = NULL; (cpu = of_find_node_by_type(cpu, "cpu")) != NULL; )
+		++nr_cores;
+
+	printk(KERN_INFO "windfarm: initializing for dual-core desktop G5\n");
+	driver_register(&wf_pm112_driver);
+	return 0;
+}
+
+static void __exit wf_pm112_exit(void)
+{
+	driver_unregister(&wf_pm112_driver);
+}
+
+module_init(wf_pm112_init);
+module_exit(wf_pm112_exit);
+
+MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
+MODULE_DESCRIPTION("Thermal control for PowerMac11,2");
+MODULE_LICENSE("GPL");