--- /dev/null
+/*
+ * 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
+ */
+
+#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 <asm/uaccess.h>
+#include <asm/sn/addrs.h>
+#include <asm/sn/clksupport.h>
+
+MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
+MODULE_DESCRIPTION("Multimedia timer support");
+MODULE_LICENSE("GPL");
+
+/* name of the device, usually in /dev */
+#define MMTIMER_NAME "mmtimer"
+#define MMTIMER_DESC "IA-PC Multimedia Timer"
+#define MMTIMER_VERSION "1.0"
+
+#define RTC_BITS 55 /* 55 bits for this implementation */
+
+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,
+};
+
+/**
+ * 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 *)arg, &mmtimer_femtoperiod,
+ sizeof(unsigned long)))
+ return -EFAULT;
+ break;
+
+ case MMTIMER_GETFREQ: /* frequency in Hz */
+ if(copy_to_user((unsigned long *)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 *)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_page_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_page_range(vma, vma->vm_start, mmtimer_addr, PAGE_SIZE,
+ vma->vm_page_prot)) {
+ printk(KERN_ERR "remap_page_range failed in mmtimer.c\n");
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static struct miscdevice mmtimer_miscdev = {
+ SGI_MMTIMER,
+ MMTIMER_NAME,
+ &mmtimer_fops
+};
+
+/**
+ * mmtimer_init - device initialization routine
+ *
+ * Does initial setup for the mmtimer device.
+ */
+static int __init mmtimer_init(void)
+{
+ 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;
+
+ 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;
+ }
+
+ 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);
+
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