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![Dimitri Sivanich](/assets/img/avatar_default.png)
For SGI UV node controllers (HUB) rev 2.0 or greater, use replicated cachelines to read the RTC timer. This optimization allows faster simulataneous reads from a given socket. Signed-off-by: Dimitri Sivanich <sivanich@sgi.com> Cc: Jack Steiner <steiner@sgi.com> LKML-Reference: <20100122154140.GB4975@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
220 lines
5.5 KiB
C
220 lines
5.5 KiB
C
/*
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* Timer device implementation for SGI UV platform.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 2009 Silicon Graphics, Inc. All rights reserved.
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*
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/ioctl.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/mmtimer.h>
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#include <linux/miscdevice.h>
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#include <linux/posix-timers.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/math64.h>
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#include <linux/smp_lock.h>
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#include <asm/genapic.h>
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#include <asm/uv/uv_hub.h>
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#include <asm/uv/bios.h>
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#include <asm/uv/uv.h>
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MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
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MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
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MODULE_LICENSE("GPL");
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/* name of the device, usually in /dev */
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#define UV_MMTIMER_NAME "mmtimer"
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#define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
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#define UV_MMTIMER_VERSION "1.0"
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static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg);
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static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
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/*
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* Period in femtoseconds (10^-15 s)
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*/
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static unsigned long uv_mmtimer_femtoperiod;
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static const struct file_operations uv_mmtimer_fops = {
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.owner = THIS_MODULE,
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.mmap = uv_mmtimer_mmap,
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.unlocked_ioctl = uv_mmtimer_ioctl,
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};
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/**
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* uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
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* @file: file structure for the device
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* @cmd: command to execute
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* @arg: optional argument to command
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*
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* Executes the command specified by @cmd. Returns 0 for success, < 0 for
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* failure.
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*
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* Valid commands:
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*
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* %MMTIMER_GETOFFSET - Should return the offset (relative to the start
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* of the page where the registers are mapped) for the counter in question.
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*
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* %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
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* seconds
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*
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* %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
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* specified by @arg
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*
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* %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
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*
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* %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
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*
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* %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
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* in the address specified by @arg.
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*/
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static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int ret = 0;
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switch (cmd) {
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case MMTIMER_GETOFFSET: /* offset of the counter */
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/*
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* Starting with HUB rev 2.0, the UV RTC register is
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* replicated across all cachelines of it's own page.
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* This allows faster simultaneous reads from a given socket.
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*
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* The offset returned is in 64 bit units.
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*/
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if (uv_get_min_hub_revision_id() == 1)
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ret = 0;
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else
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ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
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PAGE_SIZE) / 8;
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break;
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case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
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if (copy_to_user((unsigned long __user *)arg,
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&uv_mmtimer_femtoperiod, sizeof(unsigned long)))
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ret = -EFAULT;
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break;
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case MMTIMER_GETFREQ: /* frequency in Hz */
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if (copy_to_user((unsigned long __user *)arg,
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&sn_rtc_cycles_per_second,
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sizeof(unsigned long)))
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ret = -EFAULT;
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break;
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case MMTIMER_GETBITS: /* number of bits in the clock */
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ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
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break;
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case MMTIMER_MMAPAVAIL:
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ret = 1;
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break;
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case MMTIMER_GETCOUNTER:
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if (copy_to_user((unsigned long __user *)arg,
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(unsigned long *)uv_local_mmr_address(UVH_RTC),
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sizeof(unsigned long)))
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ret = -EFAULT;
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break;
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default:
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ret = -ENOTTY;
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break;
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}
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return ret;
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}
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/**
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* uv_mmtimer_mmap - maps the clock's registers into userspace
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* @file: file structure for the device
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* @vma: VMA to map the registers into
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*
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* Calls remap_pfn_range() to map the clock's registers into
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* the calling process' address space.
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*/
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static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
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{
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unsigned long uv_mmtimer_addr;
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if (vma->vm_end - vma->vm_start != PAGE_SIZE)
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return -EINVAL;
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if (vma->vm_flags & VM_WRITE)
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return -EPERM;
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if (PAGE_SIZE > (1 << 16))
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return -ENOSYS;
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
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uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
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uv_mmtimer_addr &= 0xfffffffffffffffUL;
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if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
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PAGE_SIZE, vma->vm_page_prot)) {
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printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
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return -EAGAIN;
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}
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return 0;
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}
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static struct miscdevice uv_mmtimer_miscdev = {
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MISC_DYNAMIC_MINOR,
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UV_MMTIMER_NAME,
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&uv_mmtimer_fops
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};
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/**
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* uv_mmtimer_init - device initialization routine
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*
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* Does initial setup for the uv_mmtimer device.
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*/
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static int __init uv_mmtimer_init(void)
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{
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if (!is_uv_system()) {
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printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
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return -1;
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}
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/*
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* Sanity check the cycles/sec variable
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*/
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if (sn_rtc_cycles_per_second < 100000) {
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printk(KERN_ERR "%s: unable to determine clock frequency\n",
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UV_MMTIMER_NAME);
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return -1;
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}
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uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
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sn_rtc_cycles_per_second / 2) /
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sn_rtc_cycles_per_second;
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if (misc_register(&uv_mmtimer_miscdev)) {
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printk(KERN_ERR "%s: failed to register device\n",
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UV_MMTIMER_NAME);
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return -1;
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}
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printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
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UV_MMTIMER_VERSION,
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sn_rtc_cycles_per_second/(unsigned long)1E6);
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return 0;
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}
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module_init(uv_mmtimer_init);
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