2 * Timer device implementation for SGI UV platform.
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
8 * Copyright (c) 2009 Silicon Graphics, Inc. All rights reserved.
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/ioctl.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/errno.h>
20 #include <linux/mmtimer.h>
21 #include <linux/miscdevice.h>
22 #include <linux/posix-timers.h>
23 #include <linux/interrupt.h>
24 #include <linux/time.h>
25 #include <linux/math64.h>
26 #include <linux/smp_lock.h>
28 #include <asm/genapic.h>
29 #include <asm/uv/uv_hub.h>
30 #include <asm/uv/bios.h>
31 #include <asm/uv/uv.h>
33 MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
34 MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
35 MODULE_LICENSE("GPL");
37 /* name of the device, usually in /dev */
38 #define UV_MMTIMER_NAME "mmtimer"
39 #define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
40 #define UV_MMTIMER_VERSION "1.0"
42 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
44 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
47 * Period in femtoseconds (10^-15 s)
49 static unsigned long uv_mmtimer_femtoperiod;
51 static const struct file_operations uv_mmtimer_fops = {
53 .mmap = uv_mmtimer_mmap,
54 .unlocked_ioctl = uv_mmtimer_ioctl,
55 .llseek = noop_llseek,
59 * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
60 * @file: file structure for the device
61 * @cmd: command to execute
62 * @arg: optional argument to command
64 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
69 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
70 * of the page where the registers are mapped) for the counter in question.
72 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
75 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
78 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
80 * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
82 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
83 * in the address specified by @arg.
85 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
91 case MMTIMER_GETOFFSET: /* offset of the counter */
93 * Starting with HUB rev 2.0, the UV RTC register is
94 * replicated across all cachelines of it's own page.
95 * This allows faster simultaneous reads from a given socket.
97 * The offset returned is in 64 bit units.
99 if (uv_get_min_hub_revision_id() == 1)
102 ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
106 case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
107 if (copy_to_user((unsigned long __user *)arg,
108 &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
112 case MMTIMER_GETFREQ: /* frequency in Hz */
113 if (copy_to_user((unsigned long __user *)arg,
114 &sn_rtc_cycles_per_second,
115 sizeof(unsigned long)))
119 case MMTIMER_GETBITS: /* number of bits in the clock */
120 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
123 case MMTIMER_MMAPAVAIL:
127 case MMTIMER_GETCOUNTER:
128 if (copy_to_user((unsigned long __user *)arg,
129 (unsigned long *)uv_local_mmr_address(UVH_RTC),
130 sizeof(unsigned long)))
141 * uv_mmtimer_mmap - maps the clock's registers into userspace
142 * @file: file structure for the device
143 * @vma: VMA to map the registers into
145 * Calls remap_pfn_range() to map the clock's registers into
146 * the calling process' address space.
148 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
150 unsigned long uv_mmtimer_addr;
152 if (vma->vm_end - vma->vm_start != PAGE_SIZE)
155 if (vma->vm_flags & VM_WRITE)
158 if (PAGE_SIZE > (1 << 16))
161 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
163 uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
164 uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
165 uv_mmtimer_addr &= 0xfffffffffffffffUL;
167 if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
168 PAGE_SIZE, vma->vm_page_prot)) {
169 printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
176 static struct miscdevice uv_mmtimer_miscdev = {
184 * uv_mmtimer_init - device initialization routine
186 * Does initial setup for the uv_mmtimer device.
188 static int __init uv_mmtimer_init(void)
190 if (!is_uv_system()) {
191 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
196 * Sanity check the cycles/sec variable
198 if (sn_rtc_cycles_per_second < 100000) {
199 printk(KERN_ERR "%s: unable to determine clock frequency\n",
204 uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
205 sn_rtc_cycles_per_second / 2) /
206 sn_rtc_cycles_per_second;
208 if (misc_register(&uv_mmtimer_miscdev)) {
209 printk(KERN_ERR "%s: failed to register device\n",
214 printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
216 sn_rtc_cycles_per_second/(unsigned long)1E6);
221 module_init(uv_mmtimer_init);