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-rw-r--r--arch/i386/kernel/cpuid.c246
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diff --git a/arch/i386/kernel/cpuid.c b/arch/i386/kernel/cpuid.c
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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>
27#include <linux/config.h>
28
29#include <linux/types.h>
30#include <linux/errno.h>
31#include <linux/fcntl.h>
32#include <linux/init.h>
33#include <linux/poll.h>
34#include <linux/smp.h>
35#include <linux/major.h>
36#include <linux/fs.h>
37#include <linux/smp_lock.h>
38#include <linux/fs.h>
39#include <linux/device.h>
40#include <linux/cpu.h>
41#include <linux/notifier.h>
42
43#include <asm/processor.h>
44#include <asm/msr.h>
45#include <asm/uaccess.h>
46#include <asm/system.h>
47
48static struct class_simple *cpuid_class;
49
50#ifdef CONFIG_SMP
51
52struct cpuid_command {
53 int cpu;
54 u32 reg;
55 u32 *data;
56};
57
58static void cpuid_smp_cpuid(void *cmd_block)
59{
60 struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
61
62 if (cmd->cpu == smp_processor_id())
63 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
64 &cmd->data[3]);
65}
66
67static inline void do_cpuid(int cpu, u32 reg, u32 * data)
68{
69 struct cpuid_command cmd;
70
71 preempt_disable();
72 if (cpu == smp_processor_id()) {
73 cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
74 } else {
75 cmd.cpu = cpu;
76 cmd.reg = reg;
77 cmd.data = data;
78
79 smp_call_function(cpuid_smp_cpuid, &cmd, 1, 1);
80 }
81 preempt_enable();
82}
83#else /* ! CONFIG_SMP */
84
85static inline void do_cpuid(int cpu, u32 reg, u32 * data)
86{
87 cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
88}
89
90#endif /* ! CONFIG_SMP */
91
92static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
93{
94 loff_t ret;
95
96 lock_kernel();
97
98 switch (orig) {
99 case 0:
100 file->f_pos = offset;
101 ret = file->f_pos;
102 break;
103 case 1:
104 file->f_pos += offset;
105 ret = file->f_pos;
106 break;
107 default:
108 ret = -EINVAL;
109 }
110
111 unlock_kernel();
112 return ret;
113}
114
115static ssize_t cpuid_read(struct file *file, char __user *buf,
116 size_t count, loff_t * ppos)
117{
118 char __user *tmp = buf;
119 u32 data[4];
120 size_t rv;
121 u32 reg = *ppos;
122 int cpu = iminor(file->f_dentry->d_inode);
123
124 if (count % 16)
125 return -EINVAL; /* Invalid chunk size */
126
127 for (rv = 0; count; count -= 16) {
128 do_cpuid(cpu, reg, data);
129 if (copy_to_user(tmp, &data, 16))
130 return -EFAULT;
131 tmp += 16;
132 *ppos = reg++;
133 }
134
135 return tmp - buf;
136}
137
138static int cpuid_open(struct inode *inode, struct file *file)
139{
140 unsigned int cpu = iminor(file->f_dentry->d_inode);
141 struct cpuinfo_x86 *c = &(cpu_data)[cpu];
142
143 if (cpu >= NR_CPUS || !cpu_online(cpu))
144 return -ENXIO; /* No such CPU */
145 if (c->cpuid_level < 0)
146 return -EIO; /* CPUID not supported */
147
148 return 0;
149}
150
151/*
152 * File operations we support
153 */
154static struct file_operations cpuid_fops = {
155 .owner = THIS_MODULE,
156 .llseek = cpuid_seek,
157 .read = cpuid_read,
158 .open = cpuid_open,
159};
160
161static int cpuid_class_simple_device_add(int i)
162{
163 int err = 0;
164 struct class_device *class_err;
165
166 class_err = class_simple_device_add(cpuid_class, MKDEV(CPUID_MAJOR, i), NULL, "cpu%d",i);
167 if (IS_ERR(class_err))
168 err = PTR_ERR(class_err);
169 return err;
170}
171
172static int __devinit cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
173{
174 unsigned int cpu = (unsigned long)hcpu;
175
176 switch (action) {
177 case CPU_ONLINE:
178 cpuid_class_simple_device_add(cpu);
179 break;
180 case CPU_DEAD:
181 class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));
182 break;
183 }
184 return NOTIFY_OK;
185}
186
187static struct notifier_block cpuid_class_cpu_notifier =
188{
189 .notifier_call = cpuid_class_cpu_callback,
190};
191
192static int __init cpuid_init(void)
193{
194 int i, err = 0;
195 i = 0;
196
197 if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
198 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
199 CPUID_MAJOR);
200 err = -EBUSY;
201 goto out;
202 }
203 cpuid_class = class_simple_create(THIS_MODULE, "cpuid");
204 if (IS_ERR(cpuid_class)) {
205 err = PTR_ERR(cpuid_class);
206 goto out_chrdev;
207 }
208 for_each_online_cpu(i) {
209 err = cpuid_class_simple_device_add(i);
210 if (err != 0)
211 goto out_class;
212 }
213 register_cpu_notifier(&cpuid_class_cpu_notifier);
214
215 err = 0;
216 goto out;
217
218out_class:
219 i = 0;
220 for_each_online_cpu(i) {
221 class_simple_device_remove(MKDEV(CPUID_MAJOR, i));
222 }
223 class_simple_destroy(cpuid_class);
224out_chrdev:
225 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
226out:
227 return err;
228}
229
230static void __exit cpuid_exit(void)
231{
232 int cpu = 0;
233
234 for_each_online_cpu(cpu)
235 class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));
236 class_simple_destroy(cpuid_class);
237 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
238 unregister_cpu_notifier(&cpuid_class_cpu_notifier);
239}
240
241module_init(cpuid_init);
242module_exit(cpuid_exit);
243
244MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
245MODULE_DESCRIPTION("x86 generic CPUID driver");
246MODULE_LICENSE("GPL");