blob: 493b47a0d511bd1a01dcd8985b76666f66a03971 [file] [log] [blame]
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -07001/*
2 * Timer device implementation for SGI UV platform.
3 *
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
6 * for more details.
7 *
8 * Copyright (c) 2009 Silicon Graphics, Inc. All rights reserved.
9 *
10 */
11
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>
18#include <linux/mm.h>
19#include <linux/fs.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>
27
28#include <asm/genapic.h>
29#include <asm/uv/uv_hub.h>
30#include <asm/uv/bios.h>
31#include <asm/uv/uv.h>
32
33MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
34MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
35MODULE_LICENSE("GPL");
36
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"
41
42static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
43 unsigned long arg);
44static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
45
46/*
47 * Period in femtoseconds (10^-15 s)
48 */
49static unsigned long uv_mmtimer_femtoperiod;
50
51static const struct file_operations uv_mmtimer_fops = {
52 .owner = THIS_MODULE,
53 .mmap = uv_mmtimer_mmap,
54 .unlocked_ioctl = uv_mmtimer_ioctl,
Arnd Bergmann6038f372010-08-15 18:52:59 +020055 .llseek = noop_llseek,
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -070056};
57
58/**
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
63 *
64 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
65 * failure.
66 *
67 * Valid commands:
68 *
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.
71 *
72 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
73 * seconds
74 *
75 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
76 * specified by @arg
77 *
78 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
79 *
80 * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
81 *
82 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
83 * in the address specified by @arg.
84 */
85static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
86 unsigned long arg)
87{
88 int ret = 0;
89
90 switch (cmd) {
91 case MMTIMER_GETOFFSET: /* offset of the counter */
92 /*
Dimitri Sivanichaca3bb52010-01-22 09:41:40 -060093 * 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.
96 *
97 * The offset returned is in 64 bit units.
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -070098 */
Dimitri Sivanichaca3bb52010-01-22 09:41:40 -060099 if (uv_get_min_hub_revision_id() == 1)
100 ret = 0;
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -0700101 else
Dimitri Sivanichaca3bb52010-01-22 09:41:40 -0600102 ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
103 PAGE_SIZE) / 8;
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -0700104 break;
105
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)))
109 ret = -EFAULT;
110 break;
111
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)))
116 ret = -EFAULT;
117 break;
118
119 case MMTIMER_GETBITS: /* number of bits in the clock */
120 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
121 break;
122
Dimitri Sivanichaca3bb52010-01-22 09:41:40 -0600123 case MMTIMER_MMAPAVAIL:
124 ret = 1;
Dimitri Sivanichfbd8ae12009-09-23 15:57:15 -0700125 break;
126
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)))
131 ret = -EFAULT;
132 break;
133 default:
134 ret = -ENOTTY;
135 break;
136 }
137 return ret;
138}
139
140/**
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
144 *
145 * Calls remap_pfn_range() to map the clock's registers into
146 * the calling process' address space.
147 */
148static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
149{
150 unsigned long uv_mmtimer_addr;
151
152 if (vma->vm_end - vma->vm_start != PAGE_SIZE)
153 return -EINVAL;
154
155 if (vma->vm_flags & VM_WRITE)
156 return -EPERM;
157
158 if (PAGE_SIZE > (1 << 16))
159 return -ENOSYS;
160
161 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
162
163 uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
164 uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
165 uv_mmtimer_addr &= 0xfffffffffffffffUL;
166
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");
170 return -EAGAIN;
171 }
172
173 return 0;
174}
175
176static struct miscdevice uv_mmtimer_miscdev = {
177 MISC_DYNAMIC_MINOR,
178 UV_MMTIMER_NAME,
179 &uv_mmtimer_fops
180};
181
182
183/**
184 * uv_mmtimer_init - device initialization routine
185 *
186 * Does initial setup for the uv_mmtimer device.
187 */
188static int __init uv_mmtimer_init(void)
189{
190 if (!is_uv_system()) {
191 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
192 return -1;
193 }
194
195 /*
196 * Sanity check the cycles/sec variable
197 */
198 if (sn_rtc_cycles_per_second < 100000) {
199 printk(KERN_ERR "%s: unable to determine clock frequency\n",
200 UV_MMTIMER_NAME);
201 return -1;
202 }
203
204 uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
205 sn_rtc_cycles_per_second / 2) /
206 sn_rtc_cycles_per_second;
207
208 if (misc_register(&uv_mmtimer_miscdev)) {
209 printk(KERN_ERR "%s: failed to register device\n",
210 UV_MMTIMER_NAME);
211 return -1;
212 }
213
214 printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
215 UV_MMTIMER_VERSION,
216 sn_rtc_cycles_per_second/(unsigned long)1E6);
217
218 return 0;
219}
220
221module_init(uv_mmtimer_init);