Commit | Line | Data |
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1da177e4 | 1 | /* ----------------------------------------------------------------------- * |
2347d933 PA |
2 | * |
3 | * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved | |
1da177e4 LT |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139, | |
8 | * USA; either version 2 of the License, or (at your option) any later | |
9 | * version; incorporated herein by reference. | |
10 | * | |
11 | * ----------------------------------------------------------------------- */ | |
12 | ||
13 | /* | |
1da177e4 LT |
14 | * x86 CPUID access device |
15 | * | |
16 | * This device is accessed by lseek() to the appropriate CPUID level | |
17 | * and then read in chunks of 16 bytes. A larger size means multiple | |
18 | * reads of consecutive levels. | |
19 | * | |
2347d933 PA |
20 | * The lower 32 bits of the file position is used as the incoming %eax, |
21 | * and the upper 32 bits of the file position as the incoming %ecx, | |
22 | * the latter intended for "counting" eax levels like eax=4. | |
23 | * | |
1da177e4 LT |
24 | * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on |
25 | * an SMP box will direct the access to CPU %d. | |
26 | */ | |
27 | ||
28 | #include <linux/module.h> | |
1da177e4 LT |
29 | |
30 | #include <linux/types.h> | |
31 | #include <linux/errno.h> | |
32 | #include <linux/fcntl.h> | |
33 | #include <linux/init.h> | |
34 | #include <linux/poll.h> | |
35 | #include <linux/smp.h> | |
36 | #include <linux/major.h> | |
37 | #include <linux/fs.h> | |
1da177e4 LT |
38 | #include <linux/device.h> |
39 | #include <linux/cpu.h> | |
40 | #include <linux/notifier.h> | |
f634fa94 | 41 | #include <linux/uaccess.h> |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 LT |
43 | |
44 | #include <asm/processor.h> | |
45 | #include <asm/msr.h> | |
1da177e4 | 46 | |
8874b414 | 47 | static struct class *cpuid_class; |
1da177e4 | 48 | |
2347d933 PA |
49 | struct cpuid_regs { |
50 | u32 eax, ebx, ecx, edx; | |
1da177e4 LT |
51 | }; |
52 | ||
53 | static void cpuid_smp_cpuid(void *cmd_block) | |
54 | { | |
2347d933 | 55 | struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block; |
1da177e4 | 56 | |
2347d933 PA |
57 | cpuid_count(cmd->eax, cmd->ecx, |
58 | &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx); | |
1da177e4 LT |
59 | } |
60 | ||
1da177e4 | 61 | static ssize_t cpuid_read(struct file *file, char __user *buf, |
f634fa94 | 62 | size_t count, loff_t *ppos) |
1da177e4 LT |
63 | { |
64 | char __user *tmp = buf; | |
2347d933 | 65 | struct cpuid_regs cmd; |
496ad9aa | 66 | int cpu = iminor(file_inode(file)); |
2347d933 | 67 | u64 pos = *ppos; |
9ea2b82e PA |
68 | ssize_t bytes = 0; |
69 | int err = 0; | |
1da177e4 LT |
70 | |
71 | if (count % 16) | |
72 | return -EINVAL; /* Invalid chunk size */ | |
73 | ||
6b7f430e | 74 | for (; count; count -= 16) { |
2347d933 PA |
75 | cmd.eax = pos; |
76 | cmd.ecx = pos >> 32; | |
4b46ca70 PA |
77 | err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1); |
78 | if (err) | |
9ea2b82e PA |
79 | break; |
80 | if (copy_to_user(tmp, &cmd, 16)) { | |
81 | err = -EFAULT; | |
82 | break; | |
83 | } | |
1da177e4 | 84 | tmp += 16; |
9ea2b82e | 85 | bytes += 16; |
2347d933 | 86 | *ppos = ++pos; |
1da177e4 LT |
87 | } |
88 | ||
9ea2b82e | 89 | return bytes ? bytes : err; |
1da177e4 LT |
90 | } |
91 | ||
92 | static int cpuid_open(struct inode *inode, struct file *file) | |
93 | { | |
5119e92e JC |
94 | unsigned int cpu; |
95 | struct cpuinfo_x86 *c; | |
5119e92e | 96 | |
496ad9aa | 97 | cpu = iminor(file_inode(file)); |
5a943617 JK |
98 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
99 | return -ENXIO; /* No such CPU */ | |
100 | ||
5119e92e | 101 | c = &cpu_data(cpu); |
1da177e4 | 102 | if (c->cpuid_level < 0) |
5a943617 JK |
103 | return -EIO; /* CPUID not supported */ |
104 | ||
105 | return 0; | |
1da177e4 LT |
106 | } |
107 | ||
108 | /* | |
109 | * File operations we support | |
110 | */ | |
5dfe4c96 | 111 | static const struct file_operations cpuid_fops = { |
1da177e4 | 112 | .owner = THIS_MODULE, |
b25472f9 | 113 | .llseek = no_seek_end_llseek, |
1da177e4 LT |
114 | .read = cpuid_read, |
115 | .open = cpuid_open, | |
116 | }; | |
117 | ||
148f9bb8 | 118 | static int cpuid_device_create(int cpu) |
1da177e4 | 119 | { |
07accdc1 | 120 | struct device *dev; |
1da177e4 | 121 | |
a9b12619 GKH |
122 | dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL, |
123 | "cpu%d", cpu); | |
cbda45a2 | 124 | return PTR_ERR_OR_ZERO(dev); |
1f503e77 AM |
125 | } |
126 | ||
127 | static void cpuid_device_destroy(int cpu) | |
128 | { | |
129 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); | |
1da177e4 LT |
130 | } |
131 | ||
148f9bb8 PG |
132 | static int cpuid_class_cpu_callback(struct notifier_block *nfb, |
133 | unsigned long action, void *hcpu) | |
1da177e4 LT |
134 | { |
135 | unsigned int cpu = (unsigned long)hcpu; | |
1f503e77 | 136 | int err = 0; |
1da177e4 LT |
137 | |
138 | switch (action) { | |
1f503e77 | 139 | case CPU_UP_PREPARE: |
1f503e77 | 140 | err = cpuid_device_create(cpu); |
1da177e4 | 141 | break; |
1f503e77 | 142 | case CPU_UP_CANCELED: |
b844eba2 | 143 | case CPU_UP_CANCELED_FROZEN: |
1da177e4 | 144 | case CPU_DEAD: |
1f503e77 | 145 | cpuid_device_destroy(cpu); |
1da177e4 LT |
146 | break; |
147 | } | |
a94247e7 | 148 | return notifier_from_errno(err); |
1da177e4 LT |
149 | } |
150 | ||
4daa832d | 151 | static struct notifier_block cpuid_class_cpu_notifier = |
1da177e4 LT |
152 | { |
153 | .notifier_call = cpuid_class_cpu_callback, | |
154 | }; | |
155 | ||
2c9ede55 | 156 | static char *cpuid_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
157 | { |
158 | return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt)); | |
159 | } | |
160 | ||
1da177e4 LT |
161 | static int __init cpuid_init(void) |
162 | { | |
163 | int i, err = 0; | |
164 | i = 0; | |
165 | ||
0b962d47 PA |
166 | if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS, |
167 | "cpu/cpuid", &cpuid_fops)) { | |
1da177e4 LT |
168 | printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", |
169 | CPUID_MAJOR); | |
170 | err = -EBUSY; | |
171 | goto out; | |
172 | } | |
8874b414 | 173 | cpuid_class = class_create(THIS_MODULE, "cpuid"); |
1da177e4 LT |
174 | if (IS_ERR(cpuid_class)) { |
175 | err = PTR_ERR(cpuid_class); | |
176 | goto out_chrdev; | |
177 | } | |
e454cea2 | 178 | cpuid_class->devnode = cpuid_devnode; |
4b660b38 SB |
179 | |
180 | cpu_notifier_register_begin(); | |
1da177e4 | 181 | for_each_online_cpu(i) { |
07accdc1 | 182 | err = cpuid_device_create(i); |
2347d933 | 183 | if (err != 0) |
1da177e4 LT |
184 | goto out_class; |
185 | } | |
4b660b38 SB |
186 | __register_hotcpu_notifier(&cpuid_class_cpu_notifier); |
187 | cpu_notifier_register_done(); | |
1da177e4 LT |
188 | |
189 | err = 0; | |
190 | goto out; | |
191 | ||
192 | out_class: | |
193 | i = 0; | |
194 | for_each_online_cpu(i) { | |
1f503e77 | 195 | cpuid_device_destroy(i); |
1da177e4 | 196 | } |
4b660b38 | 197 | cpu_notifier_register_done(); |
8874b414 | 198 | class_destroy(cpuid_class); |
1da177e4 | 199 | out_chrdev: |
0b962d47 | 200 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
1da177e4 LT |
201 | out: |
202 | return err; | |
203 | } | |
204 | ||
205 | static void __exit cpuid_exit(void) | |
206 | { | |
207 | int cpu = 0; | |
208 | ||
4b660b38 | 209 | cpu_notifier_register_begin(); |
1da177e4 | 210 | for_each_online_cpu(cpu) |
1f503e77 | 211 | cpuid_device_destroy(cpu); |
8874b414 | 212 | class_destroy(cpuid_class); |
da482474 | 213 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
4b660b38 SB |
214 | __unregister_hotcpu_notifier(&cpuid_class_cpu_notifier); |
215 | cpu_notifier_register_done(); | |
1da177e4 LT |
216 | } |
217 | ||
218 | module_init(cpuid_init); | |
219 | module_exit(cpuid_exit); | |
220 | ||
221 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
222 | MODULE_DESCRIPTION("x86 generic CPUID driver"); | |
223 | MODULE_LICENSE("GPL"); |