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1da177e4 LT |
1 | /* ----------------------------------------------------------------------- * |
2 | * | |
3 | * Copyright 2000 H. Peter Anvin - All Rights Reserved | |
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 | /* | |
14 | * cpuid.c | |
15 | * | |
16 | * x86 CPUID access device | |
17 | * | |
18 | * This device is accessed by lseek() to the appropriate CPUID level | |
19 | * and then read in chunks of 16 bytes. A larger size means multiple | |
20 | * reads of consecutive levels. | |
21 | * | |
22 | * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on | |
23 | * an SMP box will direct the access to CPU %d. | |
24 | */ | |
25 | ||
26 | #include <linux/module.h> | |
1da177e4 LT |
27 | |
28 | #include <linux/types.h> | |
29 | #include <linux/errno.h> | |
30 | #include <linux/fcntl.h> | |
31 | #include <linux/init.h> | |
32 | #include <linux/poll.h> | |
33 | #include <linux/smp.h> | |
34 | #include <linux/major.h> | |
35 | #include <linux/fs.h> | |
36 | #include <linux/smp_lock.h> | |
1da177e4 LT |
37 | #include <linux/device.h> |
38 | #include <linux/cpu.h> | |
39 | #include <linux/notifier.h> | |
40 | ||
41 | #include <asm/processor.h> | |
42 | #include <asm/msr.h> | |
43 | #include <asm/uaccess.h> | |
44 | #include <asm/system.h> | |
45 | ||
8874b414 | 46 | static struct class *cpuid_class; |
1da177e4 LT |
47 | |
48 | #ifdef CONFIG_SMP | |
49 | ||
50 | struct cpuid_command { | |
1da177e4 LT |
51 | u32 reg; |
52 | u32 *data; | |
53 | }; | |
54 | ||
55 | static void cpuid_smp_cpuid(void *cmd_block) | |
56 | { | |
57 | struct cpuid_command *cmd = (struct cpuid_command *)cmd_block; | |
58 | ||
ad4e680f | 59 | cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2], |
1da177e4 LT |
60 | &cmd->data[3]); |
61 | } | |
62 | ||
63 | static inline void do_cpuid(int cpu, u32 reg, u32 * data) | |
64 | { | |
65 | struct cpuid_command cmd; | |
66 | ||
67 | preempt_disable(); | |
68 | if (cpu == smp_processor_id()) { | |
69 | cpuid(reg, &data[0], &data[1], &data[2], &data[3]); | |
70 | } else { | |
1da177e4 LT |
71 | cmd.reg = reg; |
72 | cmd.data = data; | |
73 | ||
ad4e680f | 74 | smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1); |
1da177e4 LT |
75 | } |
76 | preempt_enable(); | |
77 | } | |
78 | #else /* ! CONFIG_SMP */ | |
79 | ||
80 | static inline void do_cpuid(int cpu, u32 reg, u32 * data) | |
81 | { | |
82 | cpuid(reg, &data[0], &data[1], &data[2], &data[3]); | |
83 | } | |
84 | ||
85 | #endif /* ! CONFIG_SMP */ | |
86 | ||
87 | static loff_t cpuid_seek(struct file *file, loff_t offset, int orig) | |
88 | { | |
89 | loff_t ret; | |
90 | ||
91 | lock_kernel(); | |
92 | ||
93 | switch (orig) { | |
94 | case 0: | |
95 | file->f_pos = offset; | |
96 | ret = file->f_pos; | |
97 | break; | |
98 | case 1: | |
99 | file->f_pos += offset; | |
100 | ret = file->f_pos; | |
101 | break; | |
102 | default: | |
103 | ret = -EINVAL; | |
104 | } | |
105 | ||
106 | unlock_kernel(); | |
107 | return ret; | |
108 | } | |
109 | ||
110 | static ssize_t cpuid_read(struct file *file, char __user *buf, | |
111 | size_t count, loff_t * ppos) | |
112 | { | |
113 | char __user *tmp = buf; | |
114 | u32 data[4]; | |
1da177e4 | 115 | u32 reg = *ppos; |
aab4c5a5 | 116 | int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
117 | |
118 | if (count % 16) | |
119 | return -EINVAL; /* Invalid chunk size */ | |
120 | ||
6b7f430e | 121 | for (; count; count -= 16) { |
1da177e4 LT |
122 | do_cpuid(cpu, reg, data); |
123 | if (copy_to_user(tmp, &data, 16)) | |
124 | return -EFAULT; | |
125 | tmp += 16; | |
126 | *ppos = reg++; | |
127 | } | |
128 | ||
129 | return tmp - buf; | |
130 | } | |
131 | ||
132 | static int cpuid_open(struct inode *inode, struct file *file) | |
133 | { | |
aab4c5a5 | 134 | unsigned int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
135 | struct cpuinfo_x86 *c = &(cpu_data)[cpu]; |
136 | ||
137 | if (cpu >= NR_CPUS || !cpu_online(cpu)) | |
138 | return -ENXIO; /* No such CPU */ | |
139 | if (c->cpuid_level < 0) | |
140 | return -EIO; /* CPUID not supported */ | |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
145 | /* | |
146 | * File operations we support | |
147 | */ | |
5dfe4c96 | 148 | static const struct file_operations cpuid_fops = { |
1da177e4 LT |
149 | .owner = THIS_MODULE, |
150 | .llseek = cpuid_seek, | |
151 | .read = cpuid_read, | |
152 | .open = cpuid_open, | |
153 | }; | |
154 | ||
07accdc1 | 155 | static int cpuid_device_create(int i) |
1da177e4 LT |
156 | { |
157 | int err = 0; | |
07accdc1 | 158 | struct device *dev; |
1da177e4 | 159 | |
07accdc1 GKH |
160 | dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i); |
161 | if (IS_ERR(dev)) | |
162 | err = PTR_ERR(dev); | |
1da177e4 LT |
163 | return err; |
164 | } | |
165 | ||
efe87d2b | 166 | static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) |
1da177e4 LT |
167 | { |
168 | unsigned int cpu = (unsigned long)hcpu; | |
169 | ||
170 | switch (action) { | |
171 | case CPU_ONLINE: | |
07accdc1 | 172 | cpuid_device_create(cpu); |
1da177e4 LT |
173 | break; |
174 | case CPU_DEAD: | |
07accdc1 | 175 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); |
1da177e4 LT |
176 | break; |
177 | } | |
178 | return NOTIFY_OK; | |
179 | } | |
180 | ||
74b85f37 | 181 | static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier = |
1da177e4 LT |
182 | { |
183 | .notifier_call = cpuid_class_cpu_callback, | |
184 | }; | |
185 | ||
186 | static int __init cpuid_init(void) | |
187 | { | |
188 | int i, err = 0; | |
189 | i = 0; | |
190 | ||
191 | if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) { | |
192 | printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", | |
193 | CPUID_MAJOR); | |
194 | err = -EBUSY; | |
195 | goto out; | |
196 | } | |
8874b414 | 197 | cpuid_class = class_create(THIS_MODULE, "cpuid"); |
1da177e4 LT |
198 | if (IS_ERR(cpuid_class)) { |
199 | err = PTR_ERR(cpuid_class); | |
200 | goto out_chrdev; | |
201 | } | |
202 | for_each_online_cpu(i) { | |
07accdc1 | 203 | err = cpuid_device_create(i); |
1da177e4 LT |
204 | if (err != 0) |
205 | goto out_class; | |
206 | } | |
b6a7c79a | 207 | register_hotcpu_notifier(&cpuid_class_cpu_notifier); |
1da177e4 LT |
208 | |
209 | err = 0; | |
210 | goto out; | |
211 | ||
212 | out_class: | |
213 | i = 0; | |
214 | for_each_online_cpu(i) { | |
07accdc1 | 215 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i)); |
1da177e4 | 216 | } |
8874b414 | 217 | class_destroy(cpuid_class); |
1da177e4 LT |
218 | out_chrdev: |
219 | unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); | |
220 | out: | |
221 | return err; | |
222 | } | |
223 | ||
224 | static void __exit cpuid_exit(void) | |
225 | { | |
226 | int cpu = 0; | |
227 | ||
228 | for_each_online_cpu(cpu) | |
07accdc1 | 229 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); |
8874b414 | 230 | class_destroy(cpuid_class); |
1da177e4 | 231 | unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); |
b6a7c79a | 232 | unregister_hotcpu_notifier(&cpuid_class_cpu_notifier); |
1da177e4 LT |
233 | } |
234 | ||
235 | module_init(cpuid_init); | |
236 | module_exit(cpuid_exit); | |
237 | ||
238 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
239 | MODULE_DESCRIPTION("x86 generic CPUID driver"); | |
240 | MODULE_LICENSE("GPL"); |