1 /*
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
27 #include <asm/genapic.h>
28 #include <asm/uv/uv_hub.h>
29 #include <asm/uv/bios.h>
30 #include <asm/uv/uv.h>
31
32 MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
33 MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
34 MODULE_LICENSE("GPL");
35
36 /* name of the device, usually in /dev */
37 #define UV_MMTIMER_NAME "mmtimer"
38 #define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
39 #define UV_MMTIMER_VERSION "1.0"
40
41 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
42 unsigned long arg);
43 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
44
45 /*
46 * Period in femtoseconds (10^-15 s)
47 */
48 static unsigned long uv_mmtimer_femtoperiod;
49
50 static const struct file_operations uv_mmtimer_fops = {
51 .owner = THIS_MODULE,
52 .mmap = uv_mmtimer_mmap,
53 .unlocked_ioctl = uv_mmtimer_ioctl,
54 .llseek = noop_llseek,
55 };
56
57 /**
58 * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
59 * @file: file structure for the device
60 * @cmd: command to execute
61 * @arg: optional argument to command
62 *
63 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
64 * failure.
65 *
66 * Valid commands:
67 *
68 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
69 * of the page where the registers are mapped) for the counter in question.
70 *
71 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
72 * seconds
73 *
74 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
75 * specified by @arg
76 *
77 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
78 *
79 * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
80 *
81 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
82 * in the address specified by @arg.
83 */
uv_mmtimer_ioctl(struct file * file,unsigned int cmd,unsigned long arg)84 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
85 unsigned long arg)
86 {
87 int ret = 0;
88
89 switch (cmd) {
90 case MMTIMER_GETOFFSET: /* offset of the counter */
91 /*
92 * Starting with HUB rev 2.0, the UV RTC register is
93 * replicated across all cachelines of it's own page.
94 * This allows faster simultaneous reads from a given socket.
95 *
96 * The offset returned is in 64 bit units.
97 */
98 if (uv_get_min_hub_revision_id() == 1)
99 ret = 0;
100 else
101 ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
102 PAGE_SIZE) / 8;
103 break;
104
105 case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
106 if (copy_to_user((unsigned long __user *)arg,
107 &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
108 ret = -EFAULT;
109 break;
110
111 case MMTIMER_GETFREQ: /* frequency in Hz */
112 if (copy_to_user((unsigned long __user *)arg,
113 &sn_rtc_cycles_per_second,
114 sizeof(unsigned long)))
115 ret = -EFAULT;
116 break;
117
118 case MMTIMER_GETBITS: /* number of bits in the clock */
119 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
120 break;
121
122 case MMTIMER_MMAPAVAIL:
123 ret = 1;
124 break;
125
126 case MMTIMER_GETCOUNTER:
127 if (copy_to_user((unsigned long __user *)arg,
128 (unsigned long *)uv_local_mmr_address(UVH_RTC),
129 sizeof(unsigned long)))
130 ret = -EFAULT;
131 break;
132 default:
133 ret = -ENOTTY;
134 break;
135 }
136 return ret;
137 }
138
139 /**
140 * uv_mmtimer_mmap - maps the clock's registers into userspace
141 * @file: file structure for the device
142 * @vma: VMA to map the registers into
143 *
144 * Calls remap_pfn_range() to map the clock's registers into
145 * the calling process' address space.
146 */
uv_mmtimer_mmap(struct file * file,struct vm_area_struct * vma)147 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
148 {
149 unsigned long uv_mmtimer_addr;
150
151 if (vma->vm_end - vma->vm_start != PAGE_SIZE)
152 return -EINVAL;
153
154 if (vma->vm_flags & VM_WRITE)
155 return -EPERM;
156
157 if (PAGE_SIZE > (1 << 16))
158 return -ENOSYS;
159
160 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
161
162 uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
163 uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
164 uv_mmtimer_addr &= 0xfffffffffffffffUL;
165
166 if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
167 PAGE_SIZE, vma->vm_page_prot)) {
168 printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
169 return -EAGAIN;
170 }
171
172 return 0;
173 }
174
175 static struct miscdevice uv_mmtimer_miscdev = {
176 MISC_DYNAMIC_MINOR,
177 UV_MMTIMER_NAME,
178 &uv_mmtimer_fops
179 };
180
181
182 /**
183 * uv_mmtimer_init - device initialization routine
184 *
185 * Does initial setup for the uv_mmtimer device.
186 */
uv_mmtimer_init(void)187 static int __init uv_mmtimer_init(void)
188 {
189 if (!is_uv_system()) {
190 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
191 return -1;
192 }
193
194 /*
195 * Sanity check the cycles/sec variable
196 */
197 if (sn_rtc_cycles_per_second < 100000) {
198 printk(KERN_ERR "%s: unable to determine clock frequency\n",
199 UV_MMTIMER_NAME);
200 return -1;
201 }
202
203 uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
204 sn_rtc_cycles_per_second / 2) /
205 sn_rtc_cycles_per_second;
206
207 if (misc_register(&uv_mmtimer_miscdev)) {
208 printk(KERN_ERR "%s: failed to register device\n",
209 UV_MMTIMER_NAME);
210 return -1;
211 }
212
213 printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
214 UV_MMTIMER_VERSION,
215 sn_rtc_cycles_per_second/(unsigned long)1E6);
216
217 return 0;
218 }
219
220 module_init(uv_mmtimer_init);
221