1 files changed, 725 insertions, 0 deletions

diff --git a/drivers/char/mmtimer.c b/drivers/char/mmtimer.c
new file mode 100644
index 000000000000..58eddfdd3110
--- /dev/null
+++ b/drivers/char/mmtimer.c
@@ -0,0 +1,725 @@
+/*
+ * Intel Multimedia Timer device implementation for SGI SN platforms.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2001-2004 Silicon Graphics, Inc.  All rights reserved.
+ *
+ * This driver exports an API that should be supportable by any HPET or IA-PC
+ * multimedia timer.  The code below is currently specific to the SGI Altix
+ * SHub RTC, however.
+ *
+ * 11/01/01 - jbarnes - initial revision
+ * 9/10/04 - Christoph Lameter - remove interrupt support for kernel inclusion
+ * 10/1/04 - Christoph Lameter - provide posix clock CLOCK_SGI_CYCLE
+ * 10/13/04 - Christoph Lameter, Dimitri Sivanich - provide timer interrupt
+ *              support via the posix timer interface
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/ioctl.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/mmtimer.h>
+#include <linux/miscdevice.h>
+#include <linux/posix-timers.h>
+#include <linux/interrupt.h>
+
+#include <asm/uaccess.h>
+#include <asm/sn/addrs.h>
+#include <asm/sn/intr.h>
+#include <asm/sn/shub_mmr.h>
+#include <asm/sn/nodepda.h>
+#include <asm/sn/shubio.h>
+
+MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
+MODULE_DESCRIPTION("SGI Altix RTC Timer");
+MODULE_LICENSE("GPL");
+
+/* name of the device, usually in /dev */
+#define MMTIMER_NAME "mmtimer"
+#define MMTIMER_DESC "SGI Altix RTC Timer"
+#define MMTIMER_VERSION "2.0"
+
+#define RTC_BITS 55 /* 55 bits for this implementation */
+
+extern unsigned long sn_rtc_cycles_per_second;
+
+#define RTC_COUNTER_ADDR        ((long *)LOCAL_MMR_ADDR(SH_RTC))
+
+#define rtc_time()              (*RTC_COUNTER_ADDR)
+
+static int mmtimer_ioctl(struct inode *inode, struct file *file,
+                         unsigned int cmd, unsigned long arg);
+static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
+
+/*
+ * Period in femtoseconds (10^-15 s)
+ */
+static unsigned long mmtimer_femtoperiod = 0;
+
+static struct file_operations mmtimer_fops = {
+        .owner =        THIS_MODULE,
+        .mmap =         mmtimer_mmap,
+        .ioctl =        mmtimer_ioctl,
+};
+
+/*
+ * We only have comparison registers RTC1-4 currently available per
+ * node.  RTC0 is used by SAL.
+ */
+#define NUM_COMPARATORS 3
+/* Check for an RTC interrupt pending */
+static int inline mmtimer_int_pending(int comparator)
+{
+        if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
+                        SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
+                return 1;
+        else
+                return 0;
+}
+/* Clear the RTC interrupt pending bit */
+static void inline mmtimer_clr_int_pending(int comparator)
+{
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
+                SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
+}
+
+/* Setup timer on comparator RTC1 */
+static void inline mmtimer_setup_int_0(u64 expires)
+{
+        u64 val;
+
+        /* Disable interrupt */
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
+
+        /* Initialize comparator value */
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
+
+        /* Clear pending bit */
+        mmtimer_clr_int_pending(0);
+
+        val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
+                ((u64)cpu_physical_id(smp_processor_id()) <<
+                        SH_RTC1_INT_CONFIG_PID_SHFT);
+
+        /* Set configuration */
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
+
+        /* Enable RTC interrupts */
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
+
+        /* Initialize comparator value */
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
+
+
+}
+
+/* Setup timer on comparator RTC2 */
+static void inline mmtimer_setup_int_1(u64 expires)
+{
+        u64 val;
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
+
+        mmtimer_clr_int_pending(1);
+
+        val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
+                ((u64)cpu_physical_id(smp_processor_id()) <<
+                        SH_RTC2_INT_CONFIG_PID_SHFT);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
+}
+
+/* Setup timer on comparator RTC3 */
+static void inline mmtimer_setup_int_2(u64 expires)
+{
+        u64 val;
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
+
+        mmtimer_clr_int_pending(2);
+
+        val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
+                ((u64)cpu_physical_id(smp_processor_id()) <<
+                        SH_RTC3_INT_CONFIG_PID_SHFT);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
+
+        HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
+}
+
+/*
+ * This function must be called with interrupts disabled and preemption off
+ * in order to insure that the setup succeeds in a deterministic time frame.
+ * It will check if the interrupt setup succeeded.
+ */
+static int inline mmtimer_setup(int comparator, unsigned long expires)
+{
+
+        switch (comparator) {
+        case 0:
+                mmtimer_setup_int_0(expires);
+                break;
+        case 1:
+                mmtimer_setup_int_1(expires);
+                break;
+        case 2:
+                mmtimer_setup_int_2(expires);
+                break;
+        }
+        /* We might've missed our expiration time */
+        if (rtc_time() < expires)
+                return 1;
+
+        /*
+         * If an interrupt is already pending then its okay
+         * if not then we failed
+         */
+        return mmtimer_int_pending(comparator);
+}
+
+static int inline mmtimer_disable_int(long nasid, int comparator)
+{
+        switch (comparator) {
+        case 0:
+                nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
+                        0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
+                break;
+        case 1:
+                nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
+                        0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
+                break;
+        case 2:
+                nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
+                        0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
+                break;
+        default:
+                return -EFAULT;
+        }
+        return 0;
+}
+
+#define TIMER_OFF 0xbadcabLL
+
+/* There is one of these for each comparator */
+typedef struct mmtimer {
+        spinlock_t lock ____cacheline_aligned;
+        struct k_itimer *timer;
+        int i;
+        int cpu;
+        struct tasklet_struct tasklet;
+} mmtimer_t;
+
+/*
+ * Total number of comparators is comparators/node * MAX nodes/running kernel
+ */
+static mmtimer_t timers[NUM_COMPARATORS*MAX_COMPACT_NODES];
+
+/**
+ * mmtimer_ioctl - ioctl interface for /dev/mmtimer
+ * @inode: inode of the device
+ * @file: file structure for the device
+ * @cmd: command to execute
+ * @arg: optional argument to command
+ *
+ * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
+ * failure.
+ *
+ * Valid commands:
+ *
+ * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
+ * of the page where the registers are mapped) for the counter in question.
+ *
+ * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
+ * seconds
+ *
+ * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
+ * specified by @arg
+ *
+ * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
+ *
+ * %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
+ *
+ * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
+ * in the address specified by @arg.
+ */
+static int mmtimer_ioctl(struct inode *inode, struct file *file,
+                         unsigned int cmd, unsigned long arg)
+{
+        int ret = 0;
+
+        switch (cmd) {
+        case MMTIMER_GETOFFSET: /* offset of the counter */
+                /*
+                 * SN RTC registers are on their own 64k page
+                 */
+                if(PAGE_SIZE <= (1 << 16))
+                        ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
+                else
+                        ret = -ENOSYS;
+                break;
+
+        case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
+                if(copy_to_user((unsigned long __user *)arg,
+                                &mmtimer_femtoperiod, sizeof(unsigned long)))
+                        return -EFAULT;
+                break;
+
+        case MMTIMER_GETFREQ: /* frequency in Hz */
+                if(copy_to_user((unsigned long __user *)arg,
+                                &sn_rtc_cycles_per_second,
+                                sizeof(unsigned long)))
+                        return -EFAULT;
+                ret = 0;
+                break;
+
+        case MMTIMER_GETBITS: /* number of bits in the clock */
+                ret = RTC_BITS;
+                break;
+
+        case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
+                ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
+                break;
+
+        case MMTIMER_GETCOUNTER:
+                if(copy_to_user((unsigned long __user *)arg,
+                                RTC_COUNTER_ADDR, sizeof(unsigned long)))
+                        return -EFAULT;
+                break;
+        default:
+                ret = -ENOSYS;
+                break;
+        }
+
+        return ret;
+}
+
+/**
+ * mmtimer_mmap - maps the clock's registers into userspace
+ * @file: file structure for the device
+ * @vma: VMA to map the registers into
+ *
+ * Calls remap_pfn_range() to map the clock's registers into
+ * the calling process' address space.
+ */
+static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        unsigned long mmtimer_addr;
+
+        if (vma->vm_end - vma->vm_start != PAGE_SIZE)
+                return -EINVAL;
+
+        if (vma->vm_flags & VM_WRITE)
+                return -EPERM;
+
+        if (PAGE_SIZE > (1 << 16))
+                return -ENOSYS;
+
+        vma->vm_flags |= (VM_IO | VM_SHM | VM_LOCKED );
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+        mmtimer_addr = __pa(RTC_COUNTER_ADDR);
+        mmtimer_addr &= ~(PAGE_SIZE - 1);
+        mmtimer_addr &= 0xfffffffffffffffUL;
+
+        if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
+                                        PAGE_SIZE, vma->vm_page_prot)) {
+                printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
+                return -EAGAIN;
+        }
+
+        return 0;
+}
+
+static struct miscdevice mmtimer_miscdev = {
+        SGI_MMTIMER,
+        MMTIMER_NAME,
+        &mmtimer_fops
+};
+
+static struct timespec sgi_clock_offset;
+static int sgi_clock_period;
+
+/*
+ * Posix Timer Interface
+ */
+
+static struct timespec sgi_clock_offset;
+static int sgi_clock_period;
+
+static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
+{
+        u64 nsec;
+
+        nsec = rtc_time() * sgi_clock_period
+                        + sgi_clock_offset.tv_nsec;
+        tp->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tp->tv_nsec)
+                        + sgi_clock_offset.tv_sec;
+        return 0;
+};
+
+static int sgi_clock_set(clockid_t clockid, struct timespec *tp)
+{
+
+        u64 nsec;
+        u64 rem;
+
+        nsec = rtc_time() * sgi_clock_period;
+
+        sgi_clock_offset.tv_sec = tp->tv_sec - div_long_long_rem(nsec, NSEC_PER_SEC, &rem);
+
+        if (rem <= tp->tv_nsec)
+                sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
+        else {
+                sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
+                sgi_clock_offset.tv_sec--;
+        }
+        return 0;
+}
+
+/*
+ * Schedule the next periodic interrupt. This function will attempt
+ * to schedule a periodic interrupt later if necessary. If the scheduling
+ * of an interrupt fails then the time to skip is lengthened
+ * exponentially in order to ensure that the next interrupt
+ * can be properly scheduled..
+ */
+static int inline reschedule_periodic_timer(mmtimer_t *x)
+{
+        int n;
+        struct k_itimer *t = x->timer;
+
+        t->it.mmtimer.clock = x->i;
+        t->it_overrun--;
+
+        n = 0;
+        do {
+
+                t->it.mmtimer.expires += t->it.mmtimer.incr << n;
+                t->it_overrun += 1 << n;
+                n++;
+                if (n > 20)
+                        return 1;
+
+        } while (!mmtimer_setup(x->i, t->it.mmtimer.expires));
+
+        return 0;
+}
+
+/**
+ * mmtimer_interrupt - timer interrupt handler
+ * @irq: irq received
+ * @dev_id: device the irq came from
+ * @regs: register state upon receipt of the interrupt
+ *
+ * Called when one of the comarators matches the counter, This
+ * routine will send signals to processes that have requested
+ * them.
+ *
+ * This interrupt is run in an interrupt context
+ * by the SHUB. It is therefore safe to locally access SHub
+ * registers.
+ */
+static irqreturn_t
+mmtimer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+        int i;
+        mmtimer_t *base = timers + cpuid_to_cnodeid(smp_processor_id()) *
+                                                NUM_COMPARATORS;
+        unsigned long expires = 0;
+        int result = IRQ_NONE;
+
+        /*
+         * Do this once for each comparison register
+         */
+        for (i = 0; i < NUM_COMPARATORS; i++) {
+                /* Make sure this doesn't get reused before tasklet_sched */
+                spin_lock(&base[i].lock);
+                if (base[i].cpu == smp_processor_id()) {
+                        if (base[i].timer)
+                                expires = base[i].timer->it.mmtimer.expires;
+                        /* expires test won't work with shared irqs */
+                        if ((mmtimer_int_pending(i) > 0) ||
+                                (expires && (expires < rtc_time()))) {
+                                mmtimer_clr_int_pending(i);
+                                tasklet_schedule(&base[i].tasklet);
+                                result = IRQ_HANDLED;
+                        }
+                }
+                spin_unlock(&base[i].lock);
+                expires = 0;
+        }
+        return result;
+}
+
+void mmtimer_tasklet(unsigned long data) {
+        mmtimer_t *x = (mmtimer_t *)data;
+        struct k_itimer *t = x->timer;
+        unsigned long flags;
+
+        if (t == NULL)
+                return;
+
+        /* Send signal and deal with periodic signals */
+        spin_lock_irqsave(&t->it_lock, flags);
+        spin_lock(&x->lock);
+        /* If timer was deleted between interrupt and here, leave */
+        if (t != x->timer)
+                goto out;
+        t->it_overrun = 0;
+
+        if (tasklist_lock.write_lock || posix_timer_event(t, 0) != 0) {
+
+                // printk(KERN_WARNING "mmtimer: cannot deliver signal.\n");
+
+                t->it_overrun++;
+        }
+        if(t->it.mmtimer.incr) {
+                /* Periodic timer */
+                if (reschedule_periodic_timer(x)) {
+                        printk(KERN_WARNING "mmtimer: unable to reschedule\n");
+                        x->timer = NULL;
+                }
+        } else {
+                /* Ensure we don't false trigger in mmtimer_interrupt */
+                t->it.mmtimer.expires = 0;
+        }
+        t->it_overrun_last = t->it_overrun;
+out:
+        spin_unlock(&x->lock);
+        spin_unlock_irqrestore(&t->it_lock, flags);
+}
+
+static int sgi_timer_create(struct k_itimer *timer)
+{
+        /* Insure that a newly created timer is off */
+        timer->it.mmtimer.clock = TIMER_OFF;
+        return 0;
+}
+
+/* This does not really delete a timer. It just insures
+ * that the timer is not active
+ *
+ * Assumption: it_lock is already held with irq's disabled
+ */
+static int sgi_timer_del(struct k_itimer *timr)
+{
+        int i = timr->it.mmtimer.clock;
+        cnodeid_t nodeid = timr->it.mmtimer.node;
+        mmtimer_t *t = timers + nodeid * NUM_COMPARATORS +i;
+        unsigned long irqflags;
+
+        if (i != TIMER_OFF) {
+                spin_lock_irqsave(&t->lock, irqflags);
+                mmtimer_disable_int(cnodeid_to_nasid(nodeid),i);
+                t->timer = NULL;
+                timr->it.mmtimer.clock = TIMER_OFF;
+                timr->it.mmtimer.expires = 0;
+                spin_unlock_irqrestore(&t->lock, irqflags);
+        }
+        return 0;
+}
+
+#define timespec_to_ns(x) ((x).tv_nsec + (x).tv_sec * NSEC_PER_SEC)
+#define ns_to_timespec(ts, nsec) (ts).tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &(ts).tv_nsec)
+
+/* Assumption: it_lock is already held with irq's disabled */
+static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
+{
+
+        if (timr->it.mmtimer.clock == TIMER_OFF) {
+                cur_setting->it_interval.tv_nsec = 0;
+                cur_setting->it_interval.tv_sec = 0;
+                cur_setting->it_value.tv_nsec = 0;
+                cur_setting->it_value.tv_sec =0;
+                return;
+        }
+
+        ns_to_timespec(cur_setting->it_interval, timr->it.mmtimer.incr * sgi_clock_period);
+        ns_to_timespec(cur_setting->it_value, (timr->it.mmtimer.expires - rtc_time())* sgi_clock_period);
+        return;
+}
+
+
+static int sgi_timer_set(struct k_itimer *timr, int flags,
+        struct itimerspec * new_setting,
+        struct itimerspec * old_setting)
+{
+
+        int i;
+        unsigned long when, period, irqflags;
+        int err = 0;
+        cnodeid_t nodeid;
+        mmtimer_t *base;
+
+        if (old_setting)
+                sgi_timer_get(timr, old_setting);
+
+        sgi_timer_del(timr);
+        when = timespec_to_ns(new_setting->it_value);
+        period = timespec_to_ns(new_setting->it_interval);
+
+        if (when == 0)
+                /* Clear timer */
+                return 0;
+
+        if (flags & TIMER_ABSTIME) {
+                struct timespec n;
+                unsigned long now;
+
+                getnstimeofday(&n);
+                now = timespec_to_ns(n);
+                if (when > now)
+                        when -= now;
+                else
+                        /* Fire the timer immediately */
+                        when = 0;
+        }
+
+        /*
+         * Convert to sgi clock period. Need to keep rtc_time() as near as possible
+         * to getnstimeofday() in order to be as faithful as possible to the time
+         * specified.
+         */
+        when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
+        period = (period + sgi_clock_period - 1)  / sgi_clock_period;
+
+        /*
+         * We are allocating a local SHub comparator. If we would be moved to another
+         * cpu then another SHub may be local to us. Prohibit that by switching off
+         * preemption.
+         */
+        preempt_disable();
+
+        nodeid =  cpuid_to_cnodeid(smp_processor_id());
+        base = timers + nodeid * NUM_COMPARATORS;
+retry:
+        /* Don't use an allocated timer, or a deleted one that's pending */
+        for(i = 0; i< NUM_COMPARATORS; i++) {
+                if (!base[i].timer && !base[i].tasklet.state) {
+                        break;
+                }
+        }
+
+        if (i == NUM_COMPARATORS) {
+                preempt_enable();
+                return -EBUSY;
+        }
+
+        spin_lock_irqsave(&base[i].lock, irqflags);
+
+        if (base[i].timer || base[i].tasklet.state != 0) {
+                spin_unlock_irqrestore(&base[i].lock, irqflags);
+                goto retry;
+        }
+        base[i].timer = timr;
+        base[i].cpu = smp_processor_id();
+
+        timr->it.mmtimer.clock = i;
+        timr->it.mmtimer.node = nodeid;
+        timr->it.mmtimer.incr = period;
+        timr->it.mmtimer.expires = when;
+
+        if (period == 0) {
+                if (!mmtimer_setup(i, when)) {
+                        mmtimer_disable_int(-1, i);
+                        posix_timer_event(timr, 0);
+                        timr->it.mmtimer.expires = 0;
+                }
+        } else {
+                timr->it.mmtimer.expires -= period;
+                if (reschedule_periodic_timer(base+i))
+                        err = -EINVAL;
+        }
+
+        spin_unlock_irqrestore(&base[i].lock, irqflags);
+
+        preempt_enable();
+
+        return err;
+}
+
+static struct k_clock sgi_clock = {
+        .res = 0,
+        .clock_set = sgi_clock_set,
+        .clock_get = sgi_clock_get,
+        .timer_create = sgi_timer_create,
+        .nsleep = do_posix_clock_nonanosleep,
+        .timer_set = sgi_timer_set,
+        .timer_del = sgi_timer_del,
+        .timer_get = sgi_timer_get
+};
+
+/**
+ * mmtimer_init - device initialization routine
+ *
+ * Does initial setup for the mmtimer device.
+ */
+static int __init mmtimer_init(void)
+{
+        unsigned i;
+
+        if (!ia64_platform_is("sn2"))
+                return -1;
+
+        /*
+         * Sanity check the cycles/sec variable
+         */
+        if (sn_rtc_cycles_per_second < 100000) {
+                printk(KERN_ERR "%s: unable to determine clock frequency\n",
+                       MMTIMER_NAME);
+                return -1;
+        }
+
+        mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
+                               2) / sn_rtc_cycles_per_second;
+
+        for (i=0; i< NUM_COMPARATORS*MAX_COMPACT_NODES; i++) {
+                spin_lock_init(&timers[i].lock);
+                timers[i].timer = NULL;
+                timers[i].cpu = 0;
+                timers[i].i = i % NUM_COMPARATORS;
+                tasklet_init(&timers[i].tasklet, mmtimer_tasklet, (unsigned long) (timers+i));
+        }
+
+        if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, SA_PERCPU_IRQ, MMTIMER_NAME, NULL)) {
+                printk(KERN_WARNING "%s: unable to allocate interrupt.",
+                        MMTIMER_NAME);
+                return -1;
+        }
+
+        strcpy(mmtimer_miscdev.devfs_name, MMTIMER_NAME);
+        if (misc_register(&mmtimer_miscdev)) {
+                printk(KERN_ERR "%s: failed to register device\n",
+                       MMTIMER_NAME);
+                return -1;
+        }
+
+        sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
+        register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);
+
+        printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
+               sn_rtc_cycles_per_second/(unsigned long)1E6);
+
+        return 0;
+}
+
+module_init(mmtimer_init);
+