[CPUFREQ] Move x86 drivers to drivers/cpufreq/

Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 747 insertions, 0 deletions

diff --git a/drivers/cpufreq/powernow-k7.c b/drivers/cpufreq/powernow-k7.c
new file mode 100644
index 000000000000..d71d9f372359
--- /dev/null
+++ b/drivers/cpufreq/powernow-k7.c
@@ -0,0 +1,747 @@
+/*
+ *  AMD K7 Powernow driver.
+ *  (C) 2003 Dave Jones on behalf of SuSE Labs.
+ *  (C) 2003-2004 Dave Jones <davej@redhat.com>
+ *
+ *  Licensed under the terms of the GNU GPL License version 2.
+ *  Based upon datasheets & sample CPUs kindly provided by AMD.
+ *
+ * Errata 5:
+ *  CPU may fail to execute a FID/VID change in presence of interrupt.
+ *  - We cli/sti on stepping A0 CPUs around the FID/VID transition.
+ * Errata 15:
+ *  CPU with half frequency multipliers may hang upon wakeup from disconnect.
+ *  - We disable half multipliers if ACPI is used on A0 stepping CPUs.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/dmi.h>
+#include <linux/timex.h>
+#include <linux/io.h>
+
+#include <asm/timer.h>          /* Needed for recalibrate_cpu_khz() */
+#include <asm/msr.h>
+#include <asm/system.h>
+
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+#endif
+
+#include "powernow-k7.h"
+
+#define PFX "powernow: "
+
+
+struct psb_s {
+        u8 signature[10];
+        u8 tableversion;
+        u8 flags;
+        u16 settlingtime;
+        u8 reserved1;
+        u8 numpst;
+};
+
+struct pst_s {
+        u32 cpuid;
+        u8 fsbspeed;
+        u8 maxfid;
+        u8 startvid;
+        u8 numpstates;
+};
+
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+union powernow_acpi_control_t {
+        struct {
+                unsigned long fid:5,
+                        vid:5,
+                        sgtc:20,
+                        res1:2;
+        } bits;
+        unsigned long val;
+};
+#endif
+
+/* divide by 1000 to get VCore voltage in V. */
+static const int mobile_vid_table[32] = {
+    2000, 1950, 1900, 1850, 1800, 1750, 1700, 1650,
+    1600, 1550, 1500, 1450, 1400, 1350, 1300, 0,
+    1275, 1250, 1225, 1200, 1175, 1150, 1125, 1100,
+    1075, 1050, 1025, 1000, 975, 950, 925, 0,
+};
+
+/* divide by 10 to get FID. */
+static const int fid_codes[32] = {
+    110, 115, 120, 125, 50, 55, 60, 65,
+    70, 75, 80, 85, 90, 95, 100, 105,
+    30, 190, 40, 200, 130, 135, 140, 210,
+    150, 225, 160, 165, 170, 180, -1, -1,
+};
+
+/* This parameter is used in order to force ACPI instead of legacy method for
+ * configuration purpose.
+ */
+
+static int acpi_force;
+
+static struct cpufreq_frequency_table *powernow_table;
+
+static unsigned int can_scale_bus;
+static unsigned int can_scale_vid;
+static unsigned int minimum_speed = -1;
+static unsigned int maximum_speed;
+static unsigned int number_scales;
+static unsigned int fsb;
+static unsigned int latency;
+static char have_a0;
+
+static int check_fsb(unsigned int fsbspeed)
+{
+        int delta;
+        unsigned int f = fsb / 1000;
+
+        delta = (fsbspeed > f) ? fsbspeed - f : f - fsbspeed;
+        return delta < 5;
+}
+
+static int check_powernow(void)
+{
+        struct cpuinfo_x86 *c = &cpu_data(0);
+        unsigned int maxei, eax, ebx, ecx, edx;
+
+        if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 6)) {
+#ifdef MODULE
+                printk(KERN_INFO PFX "This module only works with "
+                                "AMD K7 CPUs\n");
+#endif
+                return 0;
+        }
+
+        /* Get maximum capabilities */
+        maxei = cpuid_eax(0x80000000);
+        if (maxei < 0x80000007) {       /* Any powernow info ? */
+#ifdef MODULE
+                printk(KERN_INFO PFX "No powernow capabilities detected\n");
+#endif
+                return 0;
+        }
+
+        if ((c->x86_model == 6) && (c->x86_mask == 0)) {
+                printk(KERN_INFO PFX "K7 660[A0] core detected, "
+                                "enabling errata workarounds\n");
+                have_a0 = 1;
+        }
+
+        cpuid(0x80000007, &eax, &ebx, &ecx, &edx);
+
+        /* Check we can actually do something before we say anything.*/
+        if (!(edx & (1 << 1 | 1 << 2)))
+                return 0;
+
+        printk(KERN_INFO PFX "PowerNOW! Technology present. Can scale: ");
+
+        if (edx & 1 << 1) {
+                printk("frequency");
+                can_scale_bus = 1;
+        }
+
+        if ((edx & (1 << 1 | 1 << 2)) == 0x6)
+                printk(" and ");
+
+        if (edx & 1 << 2) {
+                printk("voltage");
+                can_scale_vid = 1;
+        }
+
+        printk(".\n");
+        return 1;
+}
+
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+static void invalidate_entry(unsigned int entry)
+{
+        powernow_table[entry].frequency = CPUFREQ_ENTRY_INVALID;
+}
+#endif
+
+static int get_ranges(unsigned char *pst)
+{
+        unsigned int j;
+        unsigned int speed;
+        u8 fid, vid;
+
+        powernow_table = kzalloc((sizeof(struct cpufreq_frequency_table) *
+                                (number_scales + 1)), GFP_KERNEL);
+        if (!powernow_table)
+                return -ENOMEM;
+
+        for (j = 0 ; j < number_scales; j++) {
+                fid = *pst++;
+
+                powernow_table[j].frequency = (fsb * fid_codes[fid]) / 10;
+                powernow_table[j].index = fid; /* lower 8 bits */
+
+                speed = powernow_table[j].frequency;
+
+                if ((fid_codes[fid] % 10) == 5) {
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+                        if (have_a0 == 1)
+                                invalidate_entry(j);
+#endif
+                }
+
+                if (speed < minimum_speed)
+                        minimum_speed = speed;
+                if (speed > maximum_speed)
+                        maximum_speed = speed;
+
+                vid = *pst++;
+                powernow_table[j].index |= (vid << 8); /* upper 8 bits */
+
+                pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
+                         "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
+                         fid_codes[fid] % 10, speed/1000, vid,
+                         mobile_vid_table[vid]/1000,
+                         mobile_vid_table[vid]%1000);
+        }
+        powernow_table[number_scales].frequency = CPUFREQ_TABLE_END;
+        powernow_table[number_scales].index = 0;
+
+        return 0;
+}
+
+
+static void change_FID(int fid)
+{
+        union msr_fidvidctl fidvidctl;
+
+        rdmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
+        if (fidvidctl.bits.FID != fid) {
+                fidvidctl.bits.SGTC = latency;
+                fidvidctl.bits.FID = fid;
+                fidvidctl.bits.VIDC = 0;
+                fidvidctl.bits.FIDC = 1;
+                wrmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
+        }
+}
+
+
+static void change_VID(int vid)
+{
+        union msr_fidvidctl fidvidctl;
+
+        rdmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
+        if (fidvidctl.bits.VID != vid) {
+                fidvidctl.bits.SGTC = latency;
+                fidvidctl.bits.VID = vid;
+                fidvidctl.bits.FIDC = 0;
+                fidvidctl.bits.VIDC = 1;
+                wrmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
+        }
+}
+
+
+static void change_speed(unsigned int index)
+{
+        u8 fid, vid;
+        struct cpufreq_freqs freqs;
+        union msr_fidvidstatus fidvidstatus;
+        int cfid;
+
+        /* fid are the lower 8 bits of the index we stored into
+         * the cpufreq frequency table in powernow_decode_bios,
+         * vid are the upper 8 bits.
+         */
+
+        fid = powernow_table[index].index & 0xFF;
+        vid = (powernow_table[index].index & 0xFF00) >> 8;
+
+        freqs.cpu = 0;
+
+        rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
+        cfid = fidvidstatus.bits.CFID;
+        freqs.old = fsb * fid_codes[cfid] / 10;
+
+        freqs.new = powernow_table[index].frequency;
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+        /* Now do the magic poking into the MSRs.  */
+
+        if (have_a0 == 1)       /* A0 errata 5 */
+                local_irq_disable();
+
+        if (freqs.old > freqs.new) {
+                /* Going down, so change FID first */
+                change_FID(fid);
+                change_VID(vid);
+        } else {
+                /* Going up, so change VID first */
+                change_VID(vid);
+                change_FID(fid);
+        }
+
+
+        if (have_a0 == 1)
+                local_irq_enable();
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+}
+
+
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+
+static struct acpi_processor_performance *acpi_processor_perf;
+
+static int powernow_acpi_init(void)
+{
+        int i;
+        int retval = 0;
+        union powernow_acpi_control_t pc;
+
+        if (acpi_processor_perf != NULL && powernow_table != NULL) {
+                retval = -EINVAL;
+                goto err0;
+        }
+
+        acpi_processor_perf = kzalloc(sizeof(struct acpi_processor_performance),
+                                      GFP_KERNEL);
+        if (!acpi_processor_perf) {
+                retval = -ENOMEM;
+                goto err0;
+        }
+
+        if (!zalloc_cpumask_var(&acpi_processor_perf->shared_cpu_map,
+                                                                GFP_KERNEL)) {
+                retval = -ENOMEM;
+                goto err05;
+        }
+
+        if (acpi_processor_register_performance(acpi_processor_perf, 0)) {
+                retval = -EIO;
+                goto err1;
+        }
+
+        if (acpi_processor_perf->control_register.space_id !=
+                        ACPI_ADR_SPACE_FIXED_HARDWARE) {
+                retval = -ENODEV;
+                goto err2;
+        }
+
+        if (acpi_processor_perf->status_register.space_id !=
+                        ACPI_ADR_SPACE_FIXED_HARDWARE) {
+                retval = -ENODEV;
+                goto err2;
+        }
+
+        number_scales = acpi_processor_perf->state_count;
+
+        if (number_scales < 2) {
+                retval = -ENODEV;
+                goto err2;
+        }
+
+        powernow_table = kzalloc((sizeof(struct cpufreq_frequency_table) *
+                                (number_scales + 1)), GFP_KERNEL);
+        if (!powernow_table) {
+                retval = -ENOMEM;
+                goto err2;
+        }
+
+        pc.val = (unsigned long) acpi_processor_perf->states[0].control;
+        for (i = 0; i < number_scales; i++) {
+                u8 fid, vid;
+                struct acpi_processor_px *state =
+                        &acpi_processor_perf->states[i];
+                unsigned int speed, speed_mhz;
+
+                pc.val = (unsigned long) state->control;
+                pr_debug("acpi:  P%d: %d MHz %d mW %d uS control %08x SGTC %d\n",
+                         i,
+                         (u32) state->core_frequency,
+                         (u32) state->power,
+                         (u32) state->transition_latency,
+                         (u32) state->control,
+                         pc.bits.sgtc);
+
+                vid = pc.bits.vid;
+                fid = pc.bits.fid;
+
+                powernow_table[i].frequency = fsb * fid_codes[fid] / 10;
+                powernow_table[i].index = fid; /* lower 8 bits */
+                powernow_table[i].index |= (vid << 8); /* upper 8 bits */
+
+                speed = powernow_table[i].frequency;
+                speed_mhz = speed / 1000;
+
+                /* processor_perflib will multiply the MHz value by 1000 to
+                 * get a KHz value (e.g. 1266000). However, powernow-k7 works
+                 * with true KHz values (e.g. 1266768). To ensure that all
+                 * powernow frequencies are available, we must ensure that
+                 * ACPI doesn't restrict them, so we round up the MHz value
+                 * to ensure that perflib's computed KHz value is greater than
+                 * or equal to powernow's KHz value.
+                 */
+                if (speed % 1000 > 0)
+                        speed_mhz++;
+
+                if ((fid_codes[fid] % 10) == 5) {
+                        if (have_a0 == 1)
+                                invalidate_entry(i);
+                }
+
+                pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
+                         "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
+                         fid_codes[fid] % 10, speed_mhz, vid,
+                         mobile_vid_table[vid]/1000,
+                         mobile_vid_table[vid]%1000);
+
+                if (state->core_frequency != speed_mhz) {
+                        state->core_frequency = speed_mhz;
+                        pr_debug("   Corrected ACPI frequency to %d\n",
+                                speed_mhz);
+                }
+
+                if (latency < pc.bits.sgtc)
+                        latency = pc.bits.sgtc;
+
+                if (speed < minimum_speed)
+                        minimum_speed = speed;
+                if (speed > maximum_speed)
+                        maximum_speed = speed;
+        }
+
+        powernow_table[i].frequency = CPUFREQ_TABLE_END;
+        powernow_table[i].index = 0;
+
+        /* notify BIOS that we exist */
+        acpi_processor_notify_smm(THIS_MODULE);
+
+        return 0;
+
+err2:
+        acpi_processor_unregister_performance(acpi_processor_perf, 0);
+err1:
+        free_cpumask_var(acpi_processor_perf->shared_cpu_map);
+err05:
+        kfree(acpi_processor_perf);
+err0:
+        printk(KERN_WARNING PFX "ACPI perflib can not be used on "
+                        "this platform\n");
+        acpi_processor_perf = NULL;
+        return retval;
+}
+#else
+static int powernow_acpi_init(void)
+{
+        printk(KERN_INFO PFX "no support for ACPI processor found."
+               "  Please recompile your kernel with ACPI processor\n");
+        return -EINVAL;
+}
+#endif
+
+static void print_pst_entry(struct pst_s *pst, unsigned int j)
+{
+        pr_debug("PST:%d (@%p)\n", j, pst);
+        pr_debug(" cpuid: 0x%x  fsb: %d  maxFID: 0x%x  startvid: 0x%x\n",
+                pst->cpuid, pst->fsbspeed, pst->maxfid, pst->startvid);
+}
+
+static int powernow_decode_bios(int maxfid, int startvid)
+{
+        struct psb_s *psb;
+        struct pst_s *pst;
+        unsigned int i, j;
+        unsigned char *p;
+        unsigned int etuple;
+        unsigned int ret;
+
+        etuple = cpuid_eax(0x80000001);
+
+        for (i = 0xC0000; i < 0xffff0 ; i += 16) {
+
+                p = phys_to_virt(i);
+
+                if (memcmp(p, "AMDK7PNOW!",  10) == 0) {
+                        pr_debug("Found PSB header at %p\n", p);
+                        psb = (struct psb_s *) p;
+                        pr_debug("Table version: 0x%x\n", psb->tableversion);
+                        if (psb->tableversion != 0x12) {
+                                printk(KERN_INFO PFX "Sorry, only v1.2 tables"
+                                                " supported right now\n");
+                                return -ENODEV;
+                        }
+
+                        pr_debug("Flags: 0x%x\n", psb->flags);
+                        if ((psb->flags & 1) == 0)
+                                pr_debug("Mobile voltage regulator\n");
+                        else
+                                pr_debug("Desktop voltage regulator\n");
+
+                        latency = psb->settlingtime;
+                        if (latency < 100) {
+                                printk(KERN_INFO PFX "BIOS set settling time "
+                                                "to %d microseconds. "
+                                                "Should be at least 100. "
+                                                "Correcting.\n", latency);
+                                latency = 100;
+                        }
+                        pr_debug("Settling Time: %d microseconds.\n",
+                                        psb->settlingtime);
+                        pr_debug("Has %d PST tables. (Only dumping ones "
+                                        "relevant to this CPU).\n",
+                                        psb->numpst);
+
+                        p += sizeof(struct psb_s);
+
+                        pst = (struct pst_s *) p;
+
+                        for (j = 0; j < psb->numpst; j++) {
+                                pst = (struct pst_s *) p;
+                                number_scales = pst->numpstates;
+
+                                if ((etuple == pst->cpuid) &&
+                                    check_fsb(pst->fsbspeed) &&
+                                    (maxfid == pst->maxfid) &&
+                                    (startvid == pst->startvid)) {
+                                        print_pst_entry(pst, j);
+                                        p = (char *)pst + sizeof(struct pst_s);
+                                        ret = get_ranges(p);
+                                        return ret;
+                                } else {
+                                        unsigned int k;
+                                        p = (char *)pst + sizeof(struct pst_s);
+                                        for (k = 0; k < number_scales; k++)
+                                                p += 2;
+                                }
+                        }
+                        printk(KERN_INFO PFX "No PST tables match this cpuid "
+                                        "(0x%x)\n", etuple);
+                        printk(KERN_INFO PFX "This is indicative of a broken "
+                                        "BIOS.\n");
+
+                        return -EINVAL;
+                }
+                p++;
+        }
+
+        return -ENODEV;
+}
+
+
+static int powernow_target(struct cpufreq_policy *policy,
+                            unsigned int target_freq,
+                            unsigned int relation)
+{
+        unsigned int newstate;
+
+        if (cpufreq_frequency_table_target(policy, powernow_table, target_freq,
+                                relation, &newstate))
+                return -EINVAL;
+
+        change_speed(newstate);
+
+        return 0;
+}
+
+
+static int powernow_verify(struct cpufreq_policy *policy)
+{
+        return cpufreq_frequency_table_verify(policy, powernow_table);
+}
+
+/*
+ * We use the fact that the bus frequency is somehow
+ * a multiple of 100000/3 khz, then we compute sgtc according
+ * to this multiple.
+ * That way, we match more how AMD thinks all of that work.
+ * We will then get the same kind of behaviour already tested under
+ * the "well-known" other OS.
+ */
+static int __cpuinit fixup_sgtc(void)
+{
+        unsigned int sgtc;
+        unsigned int m;
+
+        m = fsb / 3333;
+        if ((m % 10) >= 5)
+                m += 5;
+
+        m /= 10;
+
+        sgtc = 100 * m * latency;
+        sgtc = sgtc / 3;
+        if (sgtc > 0xfffff) {
+                printk(KERN_WARNING PFX "SGTC too large %d\n", sgtc);
+                sgtc = 0xfffff;
+        }
+        return sgtc;
+}
+
+static unsigned int powernow_get(unsigned int cpu)
+{
+        union msr_fidvidstatus fidvidstatus;
+        unsigned int cfid;
+
+        if (cpu)
+                return 0;
+        rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
+        cfid = fidvidstatus.bits.CFID;
+
+        return fsb * fid_codes[cfid] / 10;
+}
+
+
+static int __cpuinit acer_cpufreq_pst(const struct dmi_system_id *d)
+{
+        printk(KERN_WARNING PFX
+                "%s laptop with broken PST tables in BIOS detected.\n",
+                d->ident);
+        printk(KERN_WARNING PFX
+                "You need to downgrade to 3A21 (09/09/2002), or try a newer "
+                "BIOS than 3A71 (01/20/2003)\n");
+        printk(KERN_WARNING PFX
+                "cpufreq scaling has been disabled as a result of this.\n");
+        return 0;
+}
+
+/*
+ * Some Athlon laptops have really fucked PST tables.
+ * A BIOS update is all that can save them.
+ * Mention this, and disable cpufreq.
+ */
+static struct dmi_system_id __cpuinitdata powernow_dmi_table[] = {
+        {
+                .callback = acer_cpufreq_pst,
+                .ident = "Acer Aspire",
+                .matches = {
+                        DMI_MATCH(DMI_SYS_VENDOR, "Insyde Software"),
+                        DMI_MATCH(DMI_BIOS_VERSION, "3A71"),
+                },
+        },
+        { }
+};
+
+static int __cpuinit powernow_cpu_init(struct cpufreq_policy *policy)
+{
+        union msr_fidvidstatus fidvidstatus;
+        int result;
+
+        if (policy->cpu != 0)
+                return -ENODEV;
+
+        rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
+
+        recalibrate_cpu_khz();
+
+        fsb = (10 * cpu_khz) / fid_codes[fidvidstatus.bits.CFID];
+        if (!fsb) {
+                printk(KERN_WARNING PFX "can not determine bus frequency\n");
+                return -EINVAL;
+        }
+        pr_debug("FSB: %3dMHz\n", fsb/1000);
+
+        if (dmi_check_system(powernow_dmi_table) || acpi_force) {
+                printk(KERN_INFO PFX "PSB/PST known to be broken.  "
+                                "Trying ACPI instead\n");
+                result = powernow_acpi_init();
+        } else {
+                result = powernow_decode_bios(fidvidstatus.bits.MFID,
+                                fidvidstatus.bits.SVID);
+                if (result) {
+                        printk(KERN_INFO PFX "Trying ACPI perflib\n");
+                        maximum_speed = 0;
+                        minimum_speed = -1;
+                        latency = 0;
+                        result = powernow_acpi_init();
+                        if (result) {
+                                printk(KERN_INFO PFX
+                                        "ACPI and legacy methods failed\n");
+                        }
+                } else {
+                        /* SGTC use the bus clock as timer */
+                        latency = fixup_sgtc();
+                        printk(KERN_INFO PFX "SGTC: %d\n", latency);
+                }
+        }
+
+        if (result)
+                return result;
+
+        printk(KERN_INFO PFX "Minimum speed %d MHz. Maximum speed %d MHz.\n",
+                                minimum_speed/1000, maximum_speed/1000);
+
+        policy->cpuinfo.transition_latency =
+                cpufreq_scale(2000000UL, fsb, latency);
+
+        policy->cur = powernow_get(0);
+
+        cpufreq_frequency_table_get_attr(powernow_table, policy->cpu);
+
+        return cpufreq_frequency_table_cpuinfo(policy, powernow_table);
+}
+
+static int powernow_cpu_exit(struct cpufreq_policy *policy)
+{
+        cpufreq_frequency_table_put_attr(policy->cpu);
+
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+        if (acpi_processor_perf) {
+                acpi_processor_unregister_performance(acpi_processor_perf, 0);
+                free_cpumask_var(acpi_processor_perf->shared_cpu_map);
+                kfree(acpi_processor_perf);
+        }
+#endif
+
+        kfree(powernow_table);
+        return 0;
+}
+
+static struct freq_attr *powernow_table_attr[] = {
+        &cpufreq_freq_attr_scaling_available_freqs,
+        NULL,
+};
+
+static struct cpufreq_driver powernow_driver = {
+        .verify         = powernow_verify,
+        .target         = powernow_target,
+        .get            = powernow_get,
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+        .bios_limit     = acpi_processor_get_bios_limit,
+#endif
+        .init           = powernow_cpu_init,
+        .exit           = powernow_cpu_exit,
+        .name           = "powernow-k7",
+        .owner          = THIS_MODULE,
+        .attr           = powernow_table_attr,
+};
+
+static int __init powernow_init(void)
+{
+        if (check_powernow() == 0)
+                return -ENODEV;
+        return cpufreq_register_driver(&powernow_driver);
+}
+
+
+static void __exit powernow_exit(void)
+{
+        cpufreq_unregister_driver(&powernow_driver);
+}
+
+module_param(acpi_force,  int, 0444);
+MODULE_PARM_DESC(acpi_force, "Force ACPI to be used.");
+
+MODULE_AUTHOR("Dave Jones <davej@redhat.com>");
+MODULE_DESCRIPTION("Powernow driver for AMD K7 processors.");
+MODULE_LICENSE("GPL");
+
+late_initcall(powernow_init);
+module_exit(powernow_exit);
+