cpufreq: powerpc: move cpufreq driver to drivers/cpufreq

Move cpufreq driver of powerpc platform to drivers/cpufreq.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 746 insertions, 0 deletions

diff --git a/drivers/cpufreq/pmac64-cpufreq.c b/drivers/cpufreq/pmac64-cpufreq.c
new file mode 100644
index 00000000000..7ba423431cf
--- /dev/null
+++ b/drivers/cpufreq/pmac64-cpufreq.c
@@ -0,0 +1,746 @@
+/*
+ *  Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
+ *  and                       Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs,
+ * that is iMac G5 and latest single CPU desktop.
+ */
+
+#undef DEBUG
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/sections.h>
+#include <asm/cputable.h>
+#include <asm/time.h>
+#include <asm/smu.h>
+#include <asm/pmac_pfunc.h>
+
+#define DBG(fmt...) pr_debug(fmt)
+
+/* see 970FX user manual */
+
+#define SCOM_PCR 0x0aa001			/* PCR scom addr */
+
+#define PCR_HILO_SELECT		0x80000000U	/* 1 = PCR, 0 = PCRH */
+#define PCR_SPEED_FULL		0x00000000U	/* 1:1 speed value */
+#define PCR_SPEED_HALF		0x00020000U	/* 1:2 speed value */
+#define PCR_SPEED_QUARTER	0x00040000U	/* 1:4 speed value */
+#define PCR_SPEED_MASK		0x000e0000U	/* speed mask */
+#define PCR_SPEED_SHIFT		17
+#define PCR_FREQ_REQ_VALID	0x00010000U	/* freq request valid */
+#define PCR_VOLT_REQ_VALID	0x00008000U	/* volt request valid */
+#define PCR_TARGET_TIME_MASK	0x00006000U	/* target time */
+#define PCR_STATLAT_MASK	0x00001f00U	/* STATLAT value */
+#define PCR_SNOOPLAT_MASK	0x000000f0U	/* SNOOPLAT value */
+#define PCR_SNOOPACC_MASK	0x0000000fU	/* SNOOPACC value */
+
+#define SCOM_PSR 0x408001			/* PSR scom addr */
+/* warning: PSR is a 64 bits register */
+#define PSR_CMD_RECEIVED	0x2000000000000000U   /* command received */
+#define PSR_CMD_COMPLETED	0x1000000000000000U   /* command completed */
+#define PSR_CUR_SPEED_MASK	0x0300000000000000U   /* current speed */
+#define PSR_CUR_SPEED_SHIFT	(56)
+
+/*
+ * The G5 only supports two frequencies (Quarter speed is not supported)
+ */
+#define CPUFREQ_HIGH                  0
+#define CPUFREQ_LOW                   1
+
+static struct cpufreq_frequency_table g5_cpu_freqs[] = {
+	{CPUFREQ_HIGH, 		0},
+	{CPUFREQ_LOW,		0},
+	{0,			CPUFREQ_TABLE_END},
+};
+
+static struct freq_attr* g5_cpu_freqs_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+/* Power mode data is an array of the 32 bits PCR values to use for
+ * the various frequencies, retrieved from the device-tree
+ */
+static int g5_pmode_cur;
+
+static void (*g5_switch_volt)(int speed_mode);
+static int (*g5_switch_freq)(int speed_mode);
+static int (*g5_query_freq)(void);
+
+static DEFINE_MUTEX(g5_switch_mutex);
+
+static unsigned long transition_latency;
+
+#ifdef CONFIG_PMAC_SMU
+
+static const u32 *g5_pmode_data;
+static int g5_pmode_max;
+
+static struct smu_sdbp_fvt *g5_fvt_table;	/* table of op. points */
+static int g5_fvt_count;			/* number of op. points */
+static int g5_fvt_cur;				/* current op. point */
+
+/*
+ * SMU based voltage switching for Neo2 platforms
+ */
+
+static void g5_smu_switch_volt(int speed_mode)
+{
+	struct smu_simple_cmd	cmd;
+
+	DECLARE_COMPLETION_ONSTACK(comp);
+	smu_queue_simple(&cmd, SMU_CMD_POWER_COMMAND, 8, smu_done_complete,
+			 &comp, 'V', 'S', 'L', 'E', 'W',
+			 0xff, g5_fvt_cur+1, speed_mode);
+	wait_for_completion(&comp);
+}
+
+/*
+ * Platform function based voltage/vdnap switching for Neo2
+ */
+
+static struct pmf_function *pfunc_set_vdnap0;
+static struct pmf_function *pfunc_vdnap0_complete;
+
+static void g5_vdnap_switch_volt(int speed_mode)
+{
+	struct pmf_args args;
+	u32 slew, done = 0;
+	unsigned long timeout;
+
+	slew = (speed_mode == CPUFREQ_LOW) ? 1 : 0;
+	args.count = 1;
+	args.u[0].p = &slew;
+
+	pmf_call_one(pfunc_set_vdnap0, &args);
+
+	/* It's an irq GPIO so we should be able to just block here,
+	 * I'll do that later after I've properly tested the IRQ code for
+	 * platform functions
+	 */
+	timeout = jiffies + HZ/10;
+	while(!time_after(jiffies, timeout)) {
+		args.count = 1;
+		args.u[0].p = &done;
+		pmf_call_one(pfunc_vdnap0_complete, &args);
+		if (done)
+			break;
+		msleep(1);
+	}
+	if (done == 0)
+		printk(KERN_WARNING "cpufreq: Timeout in clock slewing !\n");
+}
+
+
+/*
+ * SCOM based frequency switching for 970FX rev3
+ */
+static int g5_scom_switch_freq(int speed_mode)
+{
+	unsigned long flags;
+	int to;
+
+	/* If frequency is going up, first ramp up the voltage */
+	if (speed_mode < g5_pmode_cur)
+		g5_switch_volt(speed_mode);
+
+	local_irq_save(flags);
+
+	/* Clear PCR high */
+	scom970_write(SCOM_PCR, 0);
+	/* Clear PCR low */
+       	scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
+	/* Set PCR low */
+	scom970_write(SCOM_PCR, PCR_HILO_SELECT |
+		      g5_pmode_data[speed_mode]);
+
+	/* Wait for completion */
+	for (to = 0; to < 10; to++) {
+		unsigned long psr = scom970_read(SCOM_PSR);
+
+		if ((psr & PSR_CMD_RECEIVED) == 0 &&
+		    (((psr >> PSR_CUR_SPEED_SHIFT) ^
+		      (g5_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
+		    == 0)
+			break;
+		if (psr & PSR_CMD_COMPLETED)
+			break;
+		udelay(100);
+	}
+
+	local_irq_restore(flags);
+
+	/* If frequency is going down, last ramp the voltage */
+	if (speed_mode > g5_pmode_cur)
+		g5_switch_volt(speed_mode);
+
+	g5_pmode_cur = speed_mode;
+	ppc_proc_freq = g5_cpu_freqs[speed_mode].frequency * 1000ul;
+
+	return 0;
+}
+
+static int g5_scom_query_freq(void)
+{
+	unsigned long psr = scom970_read(SCOM_PSR);
+	int i;
+
+	for (i = 0; i <= g5_pmode_max; i++)
+		if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
+		      (g5_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
+			break;
+	return i;
+}
+
+/*
+ * Fake voltage switching for platforms with missing support
+ */
+
+static void g5_dummy_switch_volt(int speed_mode)
+{
+}
+
+#endif /* CONFIG_PMAC_SMU */
+
+/*
+ * Platform function based voltage switching for PowerMac7,2 & 7,3
+ */
+
+static struct pmf_function *pfunc_cpu0_volt_high;
+static struct pmf_function *pfunc_cpu0_volt_low;
+static struct pmf_function *pfunc_cpu1_volt_high;
+static struct pmf_function *pfunc_cpu1_volt_low;
+
+static void g5_pfunc_switch_volt(int speed_mode)
+{
+	if (speed_mode == CPUFREQ_HIGH) {
+		if (pfunc_cpu0_volt_high)
+			pmf_call_one(pfunc_cpu0_volt_high, NULL);
+		if (pfunc_cpu1_volt_high)
+			pmf_call_one(pfunc_cpu1_volt_high, NULL);
+	} else {
+		if (pfunc_cpu0_volt_low)
+			pmf_call_one(pfunc_cpu0_volt_low, NULL);
+		if (pfunc_cpu1_volt_low)
+			pmf_call_one(pfunc_cpu1_volt_low, NULL);
+	}
+	msleep(10); /* should be faster , to fix */
+}
+
+/*
+ * Platform function based frequency switching for PowerMac7,2 & 7,3
+ */
+
+static struct pmf_function *pfunc_cpu_setfreq_high;
+static struct pmf_function *pfunc_cpu_setfreq_low;
+static struct pmf_function *pfunc_cpu_getfreq;
+static struct pmf_function *pfunc_slewing_done;
+
+static int g5_pfunc_switch_freq(int speed_mode)
+{
+	struct pmf_args args;
+	u32 done = 0;
+	unsigned long timeout;
+	int rc;
+
+	DBG("g5_pfunc_switch_freq(%d)\n", speed_mode);
+
+	/* If frequency is going up, first ramp up the voltage */
+	if (speed_mode < g5_pmode_cur)
+		g5_switch_volt(speed_mode);
+
+	/* Do it */
+	if (speed_mode == CPUFREQ_HIGH)
+		rc = pmf_call_one(pfunc_cpu_setfreq_high, NULL);
+	else
+		rc = pmf_call_one(pfunc_cpu_setfreq_low, NULL);
+
+	if (rc)
+		printk(KERN_WARNING "cpufreq: pfunc switch error %d\n", rc);
+
+	/* It's an irq GPIO so we should be able to just block here,
+	 * I'll do that later after I've properly tested the IRQ code for
+	 * platform functions
+	 */
+	timeout = jiffies + HZ/10;
+	while(!time_after(jiffies, timeout)) {
+		args.count = 1;
+		args.u[0].p = &done;
+		pmf_call_one(pfunc_slewing_done, &args);
+		if (done)
+			break;
+		msleep(1);
+	}
+	if (done == 0)
+		printk(KERN_WARNING "cpufreq: Timeout in clock slewing !\n");
+
+	/* If frequency is going down, last ramp the voltage */
+	if (speed_mode > g5_pmode_cur)
+		g5_switch_volt(speed_mode);
+
+	g5_pmode_cur = speed_mode;
+	ppc_proc_freq = g5_cpu_freqs[speed_mode].frequency * 1000ul;
+
+	return 0;
+}
+
+static int g5_pfunc_query_freq(void)
+{
+	struct pmf_args args;
+	u32 val = 0;
+
+	args.count = 1;
+	args.u[0].p = &val;
+	pmf_call_one(pfunc_cpu_getfreq, &args);
+	return val ? CPUFREQ_HIGH : CPUFREQ_LOW;
+}
+
+
+/*
+ * Common interface to the cpufreq core
+ */
+
+static int g5_cpufreq_verify(struct cpufreq_policy *policy)
+{
+	return cpufreq_frequency_table_verify(policy, g5_cpu_freqs);
+}
+
+static int g5_cpufreq_target(struct cpufreq_policy *policy,
+	unsigned int target_freq, unsigned int relation)
+{
+	unsigned int newstate = 0;
+	struct cpufreq_freqs freqs;
+	int rc;
+
+	if (cpufreq_frequency_table_target(policy, g5_cpu_freqs,
+			target_freq, relation, &newstate))
+		return -EINVAL;
+
+	if (g5_pmode_cur == newstate)
+		return 0;
+
+	mutex_lock(&g5_switch_mutex);
+
+	freqs.old = g5_cpu_freqs[g5_pmode_cur].frequency;
+	freqs.new = g5_cpu_freqs[newstate].frequency;
+
+	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+	rc = g5_switch_freq(newstate);
+	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+
+	mutex_unlock(&g5_switch_mutex);
+
+	return rc;
+}
+
+static unsigned int g5_cpufreq_get_speed(unsigned int cpu)
+{
+	return g5_cpu_freqs[g5_pmode_cur].frequency;
+}
+
+static int g5_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	policy->cpuinfo.transition_latency = transition_latency;
+	policy->cur = g5_cpu_freqs[g5_query_freq()].frequency;
+	/* secondary CPUs are tied to the primary one by the
+	 * cpufreq core if in the secondary policy we tell it that
+	 * it actually must be one policy together with all others. */
+	cpumask_copy(policy->cpus, cpu_online_mask);
+	cpufreq_frequency_table_get_attr(g5_cpu_freqs, policy->cpu);
+
+	return cpufreq_frequency_table_cpuinfo(policy,
+		g5_cpu_freqs);
+}
+
+
+static struct cpufreq_driver g5_cpufreq_driver = {
+	.name		= "powermac",
+	.owner		= THIS_MODULE,
+	.flags		= CPUFREQ_CONST_LOOPS,
+	.init		= g5_cpufreq_cpu_init,
+	.verify		= g5_cpufreq_verify,
+	.target		= g5_cpufreq_target,
+	.get		= g5_cpufreq_get_speed,
+	.attr 		= g5_cpu_freqs_attr,
+};
+
+
+#ifdef CONFIG_PMAC_SMU
+
+static int __init g5_neo2_cpufreq_init(struct device_node *cpus)
+{
+	struct device_node *cpunode;
+	unsigned int psize, ssize;
+	unsigned long max_freq;
+	char *freq_method, *volt_method;
+	const u32 *valp;
+	u32 pvr_hi;
+	int use_volts_vdnap = 0;
+	int use_volts_smu = 0;
+	int rc = -ENODEV;
+
+	/* Check supported platforms */
+	if (of_machine_is_compatible("PowerMac8,1") ||
+	    of_machine_is_compatible("PowerMac8,2") ||
+	    of_machine_is_compatible("PowerMac9,1"))
+		use_volts_smu = 1;
+	else if (of_machine_is_compatible("PowerMac11,2"))
+		use_volts_vdnap = 1;
+	else
+		return -ENODEV;
+
+	/* Get first CPU node */
+	for (cpunode = NULL;
+	     (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) {
+		const u32 *reg = of_get_property(cpunode, "reg", NULL);
+		if (reg == NULL || (*reg) != 0)
+			continue;
+		if (!strcmp(cpunode->type, "cpu"))
+			break;
+	}
+	if (cpunode == NULL) {
+		printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
+		return -ENODEV;
+	}
+
+	/* Check 970FX for now */
+	valp = of_get_property(cpunode, "cpu-version", NULL);
+	if (!valp) {
+		DBG("No cpu-version property !\n");
+		goto bail_noprops;
+	}
+	pvr_hi = (*valp) >> 16;
+	if (pvr_hi != 0x3c && pvr_hi != 0x44) {
+		printk(KERN_ERR "cpufreq: Unsupported CPU version\n");
+		goto bail_noprops;
+	}
+
+	/* Look for the powertune data in the device-tree */
+	g5_pmode_data = of_get_property(cpunode, "power-mode-data",&psize);
+	if (!g5_pmode_data) {
+		DBG("No power-mode-data !\n");
+		goto bail_noprops;
+	}
+	g5_pmode_max = psize / sizeof(u32) - 1;
+
+	if (use_volts_smu) {
+		const struct smu_sdbp_header *shdr;
+
+		/* Look for the FVT table */
+		shdr = smu_get_sdb_partition(SMU_SDB_FVT_ID, NULL);
+		if (!shdr)
+			goto bail_noprops;
+		g5_fvt_table = (struct smu_sdbp_fvt *)&shdr[1];
+		ssize = (shdr->len * sizeof(u32)) -
+			sizeof(struct smu_sdbp_header);
+		g5_fvt_count = ssize / sizeof(struct smu_sdbp_fvt);
+		g5_fvt_cur = 0;
+
+		/* Sanity checking */
+		if (g5_fvt_count < 1 || g5_pmode_max < 1)
+			goto bail_noprops;
+
+		g5_switch_volt = g5_smu_switch_volt;
+		volt_method = "SMU";
+	} else if (use_volts_vdnap) {
+		struct device_node *root;
+
+		root = of_find_node_by_path("/");
+		if (root == NULL) {
+			printk(KERN_ERR "cpufreq: Can't find root of "
+			       "device tree\n");
+			goto bail_noprops;
+		}
+		pfunc_set_vdnap0 = pmf_find_function(root, "set-vdnap0");
+		pfunc_vdnap0_complete =
+			pmf_find_function(root, "slewing-done");
+		if (pfunc_set_vdnap0 == NULL ||
+		    pfunc_vdnap0_complete == NULL) {
+			printk(KERN_ERR "cpufreq: Can't find required "
+			       "platform function\n");
+			goto bail_noprops;
+		}
+
+		g5_switch_volt = g5_vdnap_switch_volt;
+		volt_method = "GPIO";
+	} else {
+		g5_switch_volt = g5_dummy_switch_volt;
+		volt_method = "none";
+	}
+
+	/*
+	 * From what I see, clock-frequency is always the maximal frequency.
+	 * The current driver can not slew sysclk yet, so we really only deal
+	 * with powertune steps for now. We also only implement full freq and
+	 * half freq in this version. So far, I haven't yet seen a machine
+	 * supporting anything else.
+	 */
+	valp = of_get_property(cpunode, "clock-frequency", NULL);
+	if (!valp)
+		return -ENODEV;
+	max_freq = (*valp)/1000;
+	g5_cpu_freqs[0].frequency = max_freq;
+	g5_cpu_freqs[1].frequency = max_freq/2;
+
+	/* Set callbacks */
+	transition_latency = 12000;
+	g5_switch_freq = g5_scom_switch_freq;
+	g5_query_freq = g5_scom_query_freq;
+	freq_method = "SCOM";
+
+	/* Force apply current frequency to make sure everything is in
+	 * sync (voltage is right for example). Firmware may leave us with
+	 * a strange setting ...
+	 */
+	g5_switch_volt(CPUFREQ_HIGH);
+	msleep(10);
+	g5_pmode_cur = -1;
+	g5_switch_freq(g5_query_freq());
+
+	printk(KERN_INFO "Registering G5 CPU frequency driver\n");
+	printk(KERN_INFO "Frequency method: %s, Voltage method: %s\n",
+	       freq_method, volt_method);
+	printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
+		g5_cpu_freqs[1].frequency/1000,
+		g5_cpu_freqs[0].frequency/1000,
+		g5_cpu_freqs[g5_pmode_cur].frequency/1000);
+
+	rc = cpufreq_register_driver(&g5_cpufreq_driver);
+
+	/* We keep the CPU node on hold... hopefully, Apple G5 don't have
+	 * hotplug CPU with a dynamic device-tree ...
+	 */
+	return rc;
+
+ bail_noprops:
+	of_node_put(cpunode);
+
+	return rc;
+}
+
+#endif /* CONFIG_PMAC_SMU */
+
+
+static int __init g5_pm72_cpufreq_init(struct device_node *cpus)
+{
+	struct device_node *cpuid = NULL, *hwclock = NULL, *cpunode = NULL;
+	const u8 *eeprom = NULL;
+	const u32 *valp;
+	u64 max_freq, min_freq, ih, il;
+	int has_volt = 1, rc = 0;
+
+	DBG("cpufreq: Initializing for PowerMac7,2, PowerMac7,3 and"
+	    " RackMac3,1...\n");
+
+	/* Get first CPU node */
+	for (cpunode = NULL;
+	     (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) {
+		if (!strcmp(cpunode->type, "cpu"))
+			break;
+	}
+	if (cpunode == NULL) {
+		printk(KERN_ERR "cpufreq: Can't find any CPU node\n");
+		return -ENODEV;
+	}
+
+	/* Lookup the cpuid eeprom node */
+        cpuid = of_find_node_by_path("/u3@0,f8000000/i2c@f8001000/cpuid@a0");
+	if (cpuid != NULL)
+		eeprom = of_get_property(cpuid, "cpuid", NULL);
+	if (eeprom == NULL) {
+		printk(KERN_ERR "cpufreq: Can't find cpuid EEPROM !\n");
+		rc = -ENODEV;
+		goto bail;
+	}
+
+	/* Lookup the i2c hwclock */
+	for (hwclock = NULL;
+	     (hwclock = of_find_node_by_name(hwclock, "i2c-hwclock")) != NULL;){
+		const char *loc = of_get_property(hwclock,
+				"hwctrl-location", NULL);
+		if (loc == NULL)
+			continue;
+		if (strcmp(loc, "CPU CLOCK"))
+			continue;
+		if (!of_get_property(hwclock, "platform-get-frequency", NULL))
+			continue;
+		break;
+	}
+	if (hwclock == NULL) {
+		printk(KERN_ERR "cpufreq: Can't find i2c clock chip !\n");
+		rc = -ENODEV;
+		goto bail;
+	}
+
+	DBG("cpufreq: i2c clock chip found: %s\n", hwclock->full_name);
+
+	/* Now get all the platform functions */
+	pfunc_cpu_getfreq =
+		pmf_find_function(hwclock, "get-frequency");
+	pfunc_cpu_setfreq_high =
+		pmf_find_function(hwclock, "set-frequency-high");
+	pfunc_cpu_setfreq_low =
+		pmf_find_function(hwclock, "set-frequency-low");
+	pfunc_slewing_done =
+		pmf_find_function(hwclock, "slewing-done");
+	pfunc_cpu0_volt_high =
+		pmf_find_function(hwclock, "set-voltage-high-0");
+	pfunc_cpu0_volt_low =
+		pmf_find_function(hwclock, "set-voltage-low-0");
+	pfunc_cpu1_volt_high =
+		pmf_find_function(hwclock, "set-voltage-high-1");
+	pfunc_cpu1_volt_low =
+		pmf_find_function(hwclock, "set-voltage-low-1");
+
+	/* Check we have minimum requirements */
+	if (pfunc_cpu_getfreq == NULL || pfunc_cpu_setfreq_high == NULL ||
+	    pfunc_cpu_setfreq_low == NULL || pfunc_slewing_done == NULL) {
+		printk(KERN_ERR "cpufreq: Can't find platform functions !\n");
+		rc = -ENODEV;
+		goto bail;
+	}
+
+	/* Check that we have complete sets */
+	if (pfunc_cpu0_volt_high == NULL || pfunc_cpu0_volt_low == NULL) {
+		pmf_put_function(pfunc_cpu0_volt_high);
+		pmf_put_function(pfunc_cpu0_volt_low);
+		pfunc_cpu0_volt_high = pfunc_cpu0_volt_low = NULL;
+		has_volt = 0;
+	}
+	if (!has_volt ||
+	    pfunc_cpu1_volt_high == NULL || pfunc_cpu1_volt_low == NULL) {
+		pmf_put_function(pfunc_cpu1_volt_high);
+		pmf_put_function(pfunc_cpu1_volt_low);
+		pfunc_cpu1_volt_high = pfunc_cpu1_volt_low = NULL;
+	}
+
+	/* Note: The device tree also contains a "platform-set-values"
+	 * function for which I haven't quite figured out the usage. It
+	 * might have to be called on init and/or wakeup, I'm not too sure
+	 * but things seem to work fine without it so far ...
+	 */
+
+	/* Get max frequency from device-tree */
+	valp = of_get_property(cpunode, "clock-frequency", NULL);
+	if (!valp) {
+		printk(KERN_ERR "cpufreq: Can't find CPU frequency !\n");
+		rc = -ENODEV;
+		goto bail;
+	}
+
+	max_freq = (*valp)/1000;
+
+	/* Now calculate reduced frequency by using the cpuid input freq
+	 * ratio. This requires 64 bits math unless we are willing to lose
+	 * some precision
+	 */
+	ih = *((u32 *)(eeprom + 0x10));
+	il = *((u32 *)(eeprom + 0x20));
+
+	/* Check for machines with no useful settings */
+	if (il == ih) {
+		printk(KERN_WARNING "cpufreq: No low frequency mode available"
+		       " on this model !\n");
+		rc = -ENODEV;
+		goto bail;
+	}
+
+	min_freq = 0;
+	if (ih != 0 && il != 0)
+		min_freq = (max_freq * il) / ih;
+
+	/* Sanity check */
+	if (min_freq >= max_freq || min_freq < 1000) {
+		printk(KERN_ERR "cpufreq: Can't calculate low frequency !\n");
+		rc = -ENXIO;
+		goto bail;
+	}
+	g5_cpu_freqs[0].frequency = max_freq;
+	g5_cpu_freqs[1].frequency = min_freq;
+
+	/* Set callbacks */
+	transition_latency = CPUFREQ_ETERNAL;
+	g5_switch_volt = g5_pfunc_switch_volt;
+	g5_switch_freq = g5_pfunc_switch_freq;
+	g5_query_freq = g5_pfunc_query_freq;
+
+	/* Force apply current frequency to make sure everything is in
+	 * sync (voltage is right for example). Firmware may leave us with
+	 * a strange setting ...
+	 */
+	g5_switch_volt(CPUFREQ_HIGH);
+	msleep(10);
+	g5_pmode_cur = -1;
+	g5_switch_freq(g5_query_freq());
+
+	printk(KERN_INFO "Registering G5 CPU frequency driver\n");
+	printk(KERN_INFO "Frequency method: i2c/pfunc, "
+	       "Voltage method: %s\n", has_volt ? "i2c/pfunc" : "none");
+	printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
+		g5_cpu_freqs[1].frequency/1000,
+		g5_cpu_freqs[0].frequency/1000,
+		g5_cpu_freqs[g5_pmode_cur].frequency/1000);
+
+	rc = cpufreq_register_driver(&g5_cpufreq_driver);
+ bail:
+	if (rc != 0) {
+		pmf_put_function(pfunc_cpu_getfreq);
+		pmf_put_function(pfunc_cpu_setfreq_high);
+		pmf_put_function(pfunc_cpu_setfreq_low);
+		pmf_put_function(pfunc_slewing_done);
+		pmf_put_function(pfunc_cpu0_volt_high);
+		pmf_put_function(pfunc_cpu0_volt_low);
+		pmf_put_function(pfunc_cpu1_volt_high);
+		pmf_put_function(pfunc_cpu1_volt_low);
+	}
+	of_node_put(hwclock);
+	of_node_put(cpuid);
+	of_node_put(cpunode);
+
+	return rc;
+}
+
+static int __init g5_cpufreq_init(void)
+{
+	struct device_node *cpus;
+	int rc = 0;
+
+	cpus = of_find_node_by_path("/cpus");
+	if (cpus == NULL) {
+		DBG("No /cpus node !\n");
+		return -ENODEV;
+	}
+
+	if (of_machine_is_compatible("PowerMac7,2") ||
+	    of_machine_is_compatible("PowerMac7,3") ||
+	    of_machine_is_compatible("RackMac3,1"))
+		rc = g5_pm72_cpufreq_init(cpus);
+#ifdef CONFIG_PMAC_SMU
+	else
+		rc = g5_neo2_cpufreq_init(cpus);
+#endif /* CONFIG_PMAC_SMU */
+
+	of_node_put(cpus);
+	return rc;
+}
+
+module_init(g5_cpufreq_init);
+
+
+MODULE_LICENSE("GPL");