fedora core 6 1.2949 + vserver 2.2.0
[linux-2.6.git] / arch / i386 / kernel / cpu / cpufreq / longhaul.c
index 8ef3854..e940e00 100644 (file)
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
+#include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/string.h>
-#include <linux/pci.h>
 
 #include <asm/msr.h>
 #include <asm/timex.h>
 #include <asm/io.h>
+#include <asm/acpi.h>
+#include <linux/acpi.h>
+#include <acpi/processor.h>
 
 #include "longhaul.h"
 
 #define        CPU_EZRA_T      4
 #define        CPU_NEHEMIAH    5
 
+/* Flags */
+#define USE_ACPI_C3            (1 << 1)
+#define USE_NORTHBRIDGE                (1 << 2)
+
 static int cpu_model;
-static unsigned int numscales=16, numvscales;
+static unsigned int numscales=16;
 static unsigned int fsb;
-static int minvid, maxvid;
+
+static struct mV_pos *vrm_mV_table;
+static unsigned char *mV_vrm_table;
+struct f_msr {
+       unsigned char vrm;
+};
+static struct f_msr f_msr_table[32];
+
+static unsigned int highest_speed, lowest_speed; /* kHz */
 static unsigned int minmult, maxmult;
 static int can_scale_voltage;
-static int vrmrev;
+static struct acpi_processor *pr = NULL;
+static struct acpi_processor_cx *cx = NULL;
+static u8 longhaul_flags;
 
 /* Module parameters */
-static int dont_scale_voltage;
-
+static int scale_voltage;
+static int ignore_latency;
 
 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "longhaul", msg)
 
@@ -67,8 +84,6 @@ static int dont_scale_voltage;
 /* Clock ratios multiplied by 10 */
 static int clock_ratio[32];
 static int eblcr_table[32];
-static int voltage_table[32];
-static unsigned int highest_speed, lowest_speed; /* kHz */
 static int longhaul_version;
 static struct cpufreq_frequency_table *longhaul_table;
 
@@ -77,13 +92,17 @@ static char speedbuffer[8];
 
 static char *print_speed(int speed)
 {
-       if (speed > 1000) {
-               if (speed%1000 == 0)
-                       sprintf (speedbuffer, "%dGHz", speed/1000);
-               else
-                       sprintf (speedbuffer, "%d.%dGHz", speed/1000, (speed%1000)/100);
-       } else
-               sprintf (speedbuffer, "%dMHz", speed);
+       if (speed < 1000) {
+               snprintf(speedbuffer, sizeof(speedbuffer),"%dMHz", speed);
+               return speedbuffer;
+       }
+
+       if (speed%1000 == 0)
+               snprintf(speedbuffer, sizeof(speedbuffer),
+                       "%dGHz", speed/1000);
+       else
+               snprintf(speedbuffer, sizeof(speedbuffer),
+                       "%d.%dGHz", speed/1000, (speed%1000)/100);
 
        return speedbuffer;
 }
@@ -114,84 +133,72 @@ static int longhaul_get_cpu_mult(void)
        return eblcr_table[invalue];
 }
 
+/* For processor with BCR2 MSR */
 
-static void do_powersaver(union msr_longhaul *longhaul,
-                       unsigned int clock_ratio_index)
+static void do_longhaul1(unsigned int clock_ratio_index)
 {
-       struct pci_dev *dev;
-       unsigned long flags;
-       unsigned int tmp_mask;
-       int version;
-       int i;
-       u16 pci_cmd;
-       u16 cmd_state[64];
-
-       switch (cpu_model) {
-       case CPU_EZRA_T:
-               version = 3;
-               break;
-       case CPU_NEHEMIAH:
-               version = 0xf;
-               break;
-       default:
-               return;
-       }
-
-       rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);
-       longhaul->bits.SoftBusRatio = clock_ratio_index & 0xf;
-       longhaul->bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
-       longhaul->bits.EnableSoftBusRatio = 1;
-       longhaul->bits.RevisionKey = 0;
-
-       preempt_disable();
-       local_irq_save(flags);
-
-       /*
-        * get current pci bus master state for all devices
-        * and clear bus master bit
-        */
-       dev = NULL;
-       i = 0;
-       do {
-               dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
-               if (dev != NULL) {
-                       pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
-                       cmd_state[i++] = pci_cmd;
-                       pci_cmd &= ~PCI_COMMAND_MASTER;
-                       pci_write_config_word(dev, PCI_COMMAND, pci_cmd);
-               }
-       } while (dev != NULL);
+       union msr_bcr2 bcr2;
 
-       tmp_mask=inb(0x21);     /* works on C3. save mask. */
-       outb(0xFE,0x21);        /* TMR0 only */
-       outb(0xFF,0x80);        /* delay */
+       rdmsrl(MSR_VIA_BCR2, bcr2.val);
+       /* Enable software clock multiplier */
+       bcr2.bits.ESOFTBF = 1;
+       bcr2.bits.CLOCKMUL = clock_ratio_index;
 
+       /* Sync to timer tick */
        safe_halt();
-       wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
+       /* Change frequency on next halt or sleep */
+       wrmsrl(MSR_VIA_BCR2, bcr2.val);
+       /* Invoke transition */
+       ACPI_FLUSH_CPU_CACHE();
        halt();
 
+       /* Disable software clock multiplier */
        local_irq_disable();
+       rdmsrl(MSR_VIA_BCR2, bcr2.val);
+       bcr2.bits.ESOFTBF = 0;
+       wrmsrl(MSR_VIA_BCR2, bcr2.val);
+}
 
-       outb(tmp_mask,0x21);    /* restore mask */
+/* For processor with Longhaul MSR */
 
-       /* restore pci bus master state for all devices */
-       dev = NULL;
-       i = 0;
-       do {
-               dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
-               if (dev != NULL) {
-                       pci_cmd = cmd_state[i++];
-                       pci_write_config_byte(dev, PCI_COMMAND, pci_cmd);
-               }
-       } while (dev != NULL);
-       local_irq_restore(flags);
-       preempt_enable();
+static void do_powersaver(int cx_address, unsigned int clock_ratio_index)
+{
+       union msr_longhaul longhaul;
+       u32 t;
+
+       rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);
+       longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
+       longhaul.bits.SoftBusRatio = clock_ratio_index & 0xf;
+       longhaul.bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;
+       longhaul.bits.EnableSoftBusRatio = 1;
 
-       /* disable bus ratio bit */
-       rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);
-       longhaul->bits.EnableSoftBusRatio = 0;
-       longhaul->bits.RevisionKey = version;
-       wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);
+       if (can_scale_voltage) {
+               longhaul.bits.SoftVID = f_msr_table[clock_ratio_index].vrm;
+               longhaul.bits.EnableSoftVID = 1;
+       }
+
+       /* Sync to timer tick */
+       safe_halt();
+       /* Change frequency on next halt or sleep */
+       wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
+       if (!cx_address) {
+               ACPI_FLUSH_CPU_CACHE();
+               /* Invoke C1 */
+               halt();
+       } else {
+               ACPI_FLUSH_CPU_CACHE();
+               /* Invoke C3 */
+               inb(cx_address);
+               /* Dummy op - must do something useless after P_LVL3 read */
+               t = inl(acpi_fadt.xpm_tmr_blk.address);
+       }
+       /* Disable bus ratio bit */
+       local_irq_disable();
+       longhaul.bits.RevisionKey = longhaul.bits.RevisionID;
+       longhaul.bits.EnableSoftBusRatio = 0;
+       longhaul.bits.EnableSoftBSEL = 0;
+       longhaul.bits.EnableSoftVID = 0;
+       wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
 }
 
 /**
@@ -205,9 +212,9 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
 {
        int speed, mult;
        struct cpufreq_freqs freqs;
-       union msr_longhaul longhaul;
-       union msr_bcr2 bcr2;
        static unsigned int old_ratio=-1;
+       unsigned long flags;
+       unsigned int pic1_mask, pic2_mask;
 
        if (old_ratio == clock_ratio_index)
                return;
@@ -230,6 +237,22 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
        dprintk ("Setting to FSB:%dMHz Mult:%d.%dx (%s)\n",
                        fsb, mult/10, mult%10, print_speed(speed/1000));
 
+       preempt_disable();
+       local_irq_save(flags);
+
+       pic2_mask = inb(0xA1);
+       pic1_mask = inb(0x21);  /* works on C3. save mask. */
+       outb(0xFF,0xA1);        /* Overkill */
+       outb(0xFE,0x21);        /* TMR0 only */
+
+       if (longhaul_flags & USE_NORTHBRIDGE) {
+               /* Disable AGP and PCI arbiters */
+               outb(3, 0x22);
+       } else if ((pr != NULL) && pr->flags.bm_control) {
+               /* Disable bus master arbitration */
+               acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1,
+                                 ACPI_MTX_DO_NOT_LOCK);
+       }
        switch (longhaul_version) {
 
        /*
@@ -241,20 +264,7 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
         */
        case TYPE_LONGHAUL_V1:
        case TYPE_LONGHAUL_V2:
-               rdmsrl (MSR_VIA_BCR2, bcr2.val);
-               /* Enable software clock multiplier */
-               bcr2.bits.ESOFTBF = 1;
-               bcr2.bits.CLOCKMUL = clock_ratio_index;
-               local_irq_disable();
-               wrmsrl (MSR_VIA_BCR2, bcr2.val);
-               safe_halt();
-
-               /* Disable software clock multiplier */
-               rdmsrl (MSR_VIA_BCR2, bcr2.val);
-               bcr2.bits.ESOFTBF = 0;
-               local_irq_disable();
-               wrmsrl (MSR_VIA_BCR2, bcr2.val);
-               local_irq_enable();
+               do_longhaul1(clock_ratio_index);
                break;
 
        /*
@@ -269,10 +279,31 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
         * to work in practice.
         */
        case TYPE_POWERSAVER:
-               do_powersaver(&longhaul, clock_ratio_index);
+               if (longhaul_flags & USE_ACPI_C3) {
+                       /* Don't allow wakeup */
+                       acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0,
+                                         ACPI_MTX_DO_NOT_LOCK);
+                       do_powersaver(cx->address, clock_ratio_index);
+               } else {
+                       do_powersaver(0, clock_ratio_index);
+               }
                break;
        }
 
+       if (longhaul_flags & USE_NORTHBRIDGE) {
+               /* Enable arbiters */
+               outb(0, 0x22);
+       } else if ((pr != NULL) && pr->flags.bm_control) {
+               /* Enable bus master arbitration */
+               acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0,
+                                 ACPI_MTX_DO_NOT_LOCK);
+       }
+       outb(pic2_mask,0xA1);   /* restore mask */
+       outb(pic1_mask,0x21);
+
+       local_irq_restore(flags);
+       preempt_enable();
+
        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 }
 
@@ -287,12 +318,12 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
 
 #define ROUNDING       0xf
 
-static int _guess(int guess)
+static int _guess(int guess, int mult)
 {
        int target;
 
-       target = ((maxmult/10)*guess);
-       if (maxmult%10 != 0)
+       target = ((mult/10)*guess);
+       if (mult%10 != 0)
                target += (guess/2);
        target += ROUNDING/2;
        target &= ~ROUNDING;
@@ -300,17 +331,17 @@ static int _guess(int guess)
 }
 
 
-static int guess_fsb(void)
+static int guess_fsb(int mult)
 {
        int speed = (cpu_khz/1000);
        int i;
-       int speeds[3] = { 66, 100, 133 };
+       int speeds[] = { 66, 100, 133, 200 };
 
        speed += ROUNDING/2;
        speed &= ~ROUNDING;
 
-       for (i=0; i<3; i++) {
-               if (_guess(speeds[i]) == speed)
+       for (i=0; i<4; i++) {
+               if (_guess(speeds[i], mult) == speed)
                        return speeds[i];
        }
        return 0;
@@ -320,14 +351,14 @@ static int guess_fsb(void)
 static int __init longhaul_get_ranges(void)
 {
        unsigned long invalue;
-       unsigned int multipliers[32]= {
-               50,30,40,100,55,35,45,95,90,70,80,60,120,75,85,65,
-               -1,110,120,-1,135,115,125,105,130,150,160,140,-1,155,-1,145 };
+       unsigned int ezra_t_multipliers[32]= {
+                       90,  30,  40, 100,  55,  35,  45,  95,
+                       50,  70,  80,  60, 120,  75,  85,  65,
+                       -1, 110, 120,  -1, 135, 115, 125, 105,
+                       130, 150, 160, 140,  -1, 155,  -1, 145 };
        unsigned int j, k = 0;
        union msr_longhaul longhaul;
-       unsigned long lo, hi;
-       unsigned int eblcr_fsb_table_v1[] = { 66, 133, 100, -1 };
-       unsigned int eblcr_fsb_table_v2[] = { 133, 100, -1, 66 };
+       int mult = 0;
 
        switch (longhaul_version) {
        case TYPE_LONGHAUL_V1:
@@ -335,30 +366,18 @@ static int __init longhaul_get_ranges(void)
                /* Ugh, Longhaul v1 didn't have the min/max MSRs.
                   Assume min=3.0x & max = whatever we booted at. */
                minmult = 30;
-               maxmult = longhaul_get_cpu_mult();
-               rdmsr (MSR_IA32_EBL_CR_POWERON, lo, hi);
-               invalue = (lo & (1<<18|1<<19)) >>18;
-               if (cpu_model==CPU_SAMUEL || cpu_model==CPU_SAMUEL2)
-                       fsb = eblcr_fsb_table_v1[invalue];
-               else
-                       fsb = guess_fsb();
+               maxmult = mult = longhaul_get_cpu_mult();
                break;
 
        case TYPE_POWERSAVER:
                /* Ezra-T */
                if (cpu_model==CPU_EZRA_T) {
+                       minmult = 30;
                        rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
                        invalue = longhaul.bits.MaxMHzBR;
                        if (longhaul.bits.MaxMHzBR4)
                                invalue += 16;
-                       maxmult=multipliers[invalue];
-
-                       invalue = longhaul.bits.MinMHzBR;
-                       if (longhaul.bits.MinMHzBR4 == 1)
-                               minmult = 30;
-                       else
-                               minmult = multipliers[invalue];
-                       fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
+                       maxmult = mult = ezra_t_multipliers[invalue];
                        break;
                }
 
@@ -378,21 +397,16 @@ static int __init longhaul_get_ranges(void)
                         *   But it works, so we don't grumble.
                         */
                        minmult=40;
-                       maxmult=longhaul_get_cpu_mult();
-
-                       /* Starting with the 1.2GHz parts, theres a 200MHz bus. */
-                       if ((cpu_khz/1000) > 1200)
-                               fsb = 200;
-                       else
-                               fsb = eblcr_fsb_table_v2[longhaul.bits.MaxMHzFSB];
+                       maxmult = mult = longhaul_get_cpu_mult();
                        break;
                }
        }
+       fsb = guess_fsb(mult);
 
        dprintk ("MinMult:%d.%dx MaxMult:%d.%dx\n",
                 minmult/10, minmult%10, maxmult/10, maxmult%10);
 
-       if (fsb == -1) {
+       if (fsb == 0) {
                printk (KERN_INFO PFX "Invalid (reserved) FSB!\n");
                return -EINVAL;
        }
@@ -442,53 +456,57 @@ static int __init longhaul_get_ranges(void)
 static void __init longhaul_setup_voltagescaling(void)
 {
        union msr_longhaul longhaul;
+       struct mV_pos minvid, maxvid;
+       unsigned int j, speed, pos, kHz_step, numvscales;
 
-       rdmsrl (MSR_VIA_LONGHAUL, longhaul.val);
-
-       if (!(longhaul.bits.RevisionID & 1))
+       rdmsrl(MSR_VIA_LONGHAUL, longhaul.val);
+       if (!(longhaul.bits.RevisionID & 1)) {
+               printk(KERN_INFO PFX "Voltage scaling not supported by CPU.\n");
                return;
+       }
 
-       minvid = longhaul.bits.MinimumVID;
-       maxvid = longhaul.bits.MaximumVID;
-       vrmrev = longhaul.bits.VRMRev;
+       if (!longhaul.bits.VRMRev) {
+               printk (KERN_INFO PFX "VRM 8.5\n");
+               vrm_mV_table = &vrm85_mV[0];
+               mV_vrm_table = &mV_vrm85[0];
+       } else {
+               printk (KERN_INFO PFX "Mobile VRM\n");
+               vrm_mV_table = &mobilevrm_mV[0];
+               mV_vrm_table = &mV_mobilevrm[0];
+       }
 
-       if (minvid == 0 || maxvid == 0) {
+       minvid = vrm_mV_table[longhaul.bits.MinimumVID];
+       maxvid = vrm_mV_table[longhaul.bits.MaximumVID];
+       numvscales = maxvid.pos - minvid.pos + 1;
+       kHz_step = (highest_speed - lowest_speed) / numvscales;
+
+       if (minvid.mV == 0 || maxvid.mV == 0 || minvid.mV > maxvid.mV) {
                printk (KERN_INFO PFX "Bogus values Min:%d.%03d Max:%d.%03d. "
                                        "Voltage scaling disabled.\n",
-                                       minvid/1000, minvid%1000, maxvid/1000, maxvid%1000);
+                                       minvid.mV/1000, minvid.mV%1000, maxvid.mV/1000, maxvid.mV%1000);
                return;
        }
 
-       if (minvid == maxvid) {
+       if (minvid.mV == maxvid.mV) {
                printk (KERN_INFO PFX "Claims to support voltage scaling but min & max are "
                                "both %d.%03d. Voltage scaling disabled\n",
-                               maxvid/1000, maxvid%1000);
+                               maxvid.mV/1000, maxvid.mV%1000);
                return;
        }
 
-       if (vrmrev==0) {
-               dprintk ("VRM 8.5\n");
-               memcpy (voltage_table, vrm85scales, sizeof(voltage_table));
-               numvscales = (voltage_table[maxvid]-voltage_table[minvid])/25;
-       } else {
-               dprintk ("Mobile VRM\n");
-               memcpy (voltage_table, mobilevrmscales, sizeof(voltage_table));
-               numvscales = (voltage_table[maxvid]-voltage_table[minvid])/5;
+       printk(KERN_INFO PFX "Max VID=%d.%03d  Min VID=%d.%03d, %d possible voltage scales\n",
+               maxvid.mV/1000, maxvid.mV%1000,
+               minvid.mV/1000, minvid.mV%1000,
+               numvscales);
+       
+       j = 0;
+       while (longhaul_table[j].frequency != CPUFREQ_TABLE_END) {
+               speed = longhaul_table[j].frequency;
+               pos = (speed - lowest_speed) / kHz_step + minvid.pos;
+               f_msr_table[longhaul_table[j].index].vrm = mV_vrm_table[pos];
+               j++;
        }
 
-       /* Current voltage isn't readable at first, so we need to
-          set it to a known value. The spec says to use maxvid */
-       longhaul.bits.RevisionKey = longhaul.bits.RevisionID;   /* FIXME: This is bad. */
-       longhaul.bits.EnableSoftVID = 1;
-       longhaul.bits.SoftVID = maxvid;
-       wrmsrl (MSR_VIA_LONGHAUL, longhaul.val);
-
-       minvid = voltage_table[minvid];
-       maxvid = voltage_table[maxvid];
-
-       dprintk ("Min VID=%d.%03d Max VID=%d.%03d, %d possible voltage scales\n",
-               maxvid/1000, maxvid%1000, minvid/1000, minvid%1000, numvscales);
-
        can_scale_voltage = 1;
 }
 
@@ -523,6 +541,49 @@ static unsigned int longhaul_get(unsigned int cpu)
        return calc_speed(longhaul_get_cpu_mult());
 }
 
+static acpi_status longhaul_walk_callback(acpi_handle obj_handle,
+                                         u32 nesting_level,
+                                         void *context, void **return_value)
+{
+       struct acpi_device *d;
+
+       if ( acpi_bus_get_device(obj_handle, &d) ) {
+               return 0;
+       }
+       *return_value = (void *)acpi_driver_data(d);
+       return 1;
+}
+
+/* VIA don't support PM2 reg, but have something similar */
+static int enable_arbiter_disable(void)
+{
+       struct pci_dev *dev;
+       int reg;
+       u8 pci_cmd;
+
+       /* Find PLE133 host bridge */
+       reg = 0x78;
+       dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8601_0, NULL);
+       /* Find CLE266 host bridge */
+       if (dev == NULL) {
+               reg = 0x76;
+               dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_862X_0, NULL);
+               /* Find CN400 V-Link host bridge */
+               if (dev == NULL)
+                       dev = pci_find_device(PCI_VENDOR_ID_VIA, 0x7259, NULL);
+
+       }
+       if (dev != NULL) {
+               /* Enable access to port 0x22 */
+               pci_read_config_byte(dev, reg, &pci_cmd);
+               if ( !(pci_cmd & 1<<7) ) {
+                       pci_cmd |= 1<<7;
+                       pci_write_config_byte(dev, reg, pci_cmd);
+               }
+               return 1;
+       }
+       return 0;
+}
 
 static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 {
@@ -530,6 +591,7 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
        char *cpuname=NULL;
        int ret;
 
+       /* Check what we have on this motherboard */
        switch (c->x86_model) {
        case 6:
                cpu_model = CPU_SAMUEL;
@@ -611,12 +673,46 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
                break;
        };
 
+       /* Find ACPI data for processor */
+       acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
+                           &longhaul_walk_callback, NULL, (void *)&pr);
+
+       /* Check ACPI support for C3 state */
+       if ((pr != NULL) && (longhaul_version == TYPE_POWERSAVER)) {
+               cx = &pr->power.states[ACPI_STATE_C3];
+               if (cx->address > 0 &&
+                  (cx->latency <= 1000 || ignore_latency != 0) ) {
+                       longhaul_flags |= USE_ACPI_C3;
+                       goto print_support_type;
+               }
+       }
+       /* Check if northbridge is friendly */
+       if (enable_arbiter_disable()) {
+               longhaul_flags |= USE_NORTHBRIDGE;
+               goto print_support_type;
+       }
+
+       /* No ACPI C3 or we can't use it */
+       /* Check ACPI support for bus master arbiter disable */
+       if ((pr == NULL) || !(pr->flags.bm_control)) {
+               printk(KERN_ERR PFX
+                       "No ACPI support. Unsupported northbridge.\n");
+               return -ENODEV;
+       }
+
+print_support_type:
+       if (!(longhaul_flags & USE_NORTHBRIDGE)) {
+               printk (KERN_INFO PFX "Using ACPI support.\n");
+       } else {
+               printk (KERN_INFO PFX "Using northbridge support.\n");
+       }
+
        ret = longhaul_get_ranges();
        if (ret != 0)
                return ret;
 
        if ((longhaul_version==TYPE_LONGHAUL_V2 || longhaul_version==TYPE_POWERSAVER) &&
-                (dont_scale_voltage==0))
+                (scale_voltage != 0))
                longhaul_setup_voltagescaling();
 
        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
@@ -662,11 +758,25 @@ static int __init longhaul_init(void)
        if (c->x86_vendor != X86_VENDOR_CENTAUR || c->x86 != 6)
                return -ENODEV;
 
+#ifdef CONFIG_SMP
+       if (num_online_cpus() > 1) {
+               printk(KERN_ERR PFX "More than 1 CPU detected, longhaul disabled.\n");
+               return -ENODEV;
+       }
+#endif
+#ifdef CONFIG_X86_IO_APIC
+       if (cpu_has_apic) {
+               printk(KERN_ERR PFX "APIC detected. Longhaul is currently broken in this configuration.\n");
+               return -ENODEV;
+       }
+#endif
        switch (c->x86_model) {
        case 6 ... 9:
                return cpufreq_register_driver(&longhaul_driver);
+       case 10:
+               printk(KERN_ERR PFX "Use acpi-cpufreq driver for VIA C7\n");
        default:
-               printk (KERN_INFO PFX "Unknown VIA CPU. Contact davej@codemonkey.org.uk\n");
+               ;;
        }
 
        return -ENODEV;
@@ -675,7 +785,7 @@ static int __init longhaul_init(void)
 
 static void __exit longhaul_exit(void)
 {
-       int i=0;
+       int i;
 
        for (i=0; i < numscales; i++) {
                if (clock_ratio[i] == maxmult) {
@@ -688,13 +798,14 @@ static void __exit longhaul_exit(void)
        kfree(longhaul_table);
 }
 
-module_param (dont_scale_voltage, int, 0644);
-MODULE_PARM_DESC(dont_scale_voltage, "Don't scale voltage of processor");
+module_param (scale_voltage, int, 0644);
+MODULE_PARM_DESC(scale_voltage, "Scale voltage of processor");
+module_param(ignore_latency, int, 0644);
+MODULE_PARM_DESC(ignore_latency, "Skip ACPI C3 latency test");
 
 MODULE_AUTHOR ("Dave Jones <davej@codemonkey.org.uk>");
 MODULE_DESCRIPTION ("Longhaul driver for VIA Cyrix processors.");
 MODULE_LICENSE ("GPL");
 
-module_init(longhaul_init);
+late_initcall(longhaul_init);
 module_exit(longhaul_exit);
-