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 000000000000..7ba423431cfe
--- /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");