Linux-2.6.12-rc2
[linux-2.6/kvm.git] / arch / i386 / kernel / cpuid.c
blob2e2756345bb23964f763ff747e284c7e89050678
1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2000 H. Peter Anvin - All Rights Reserved
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.
11 * ----------------------------------------------------------------------- */
14 * cpuid.c
16 * x86 CPUID access device
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.
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.
26 #include <linux/module.h>
27 #include <linux/config.h>
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>
43 #include <asm/processor.h>
44 #include <asm/msr.h>
45 #include <asm/uaccess.h>
46 #include <asm/system.h>
48 static struct class_simple *cpuid_class;
50 #ifdef CONFIG_SMP
52 struct cpuid_command {
53 int cpu;
54 u32 reg;
55 u32 *data;
58 static void cpuid_smp_cpuid(void *cmd_block)
60 struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
62 if (cmd->cpu == smp_processor_id())
63 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
64 &cmd->data[3]);
67 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
69 struct cpuid_command cmd;
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;
79 smp_call_function(cpuid_smp_cpuid, &cmd, 1, 1);
81 preempt_enable();
83 #else /* ! CONFIG_SMP */
85 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
87 cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
90 #endif /* ! CONFIG_SMP */
92 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
94 loff_t ret;
96 lock_kernel();
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;
111 unlock_kernel();
112 return ret;
115 static ssize_t cpuid_read(struct file *file, char __user *buf,
116 size_t count, loff_t * ppos)
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);
124 if (count % 16)
125 return -EINVAL; /* Invalid chunk size */
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++;
135 return tmp - buf;
138 static int cpuid_open(struct inode *inode, struct file *file)
140 unsigned int cpu = iminor(file->f_dentry->d_inode);
141 struct cpuinfo_x86 *c = &(cpu_data)[cpu];
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 */
148 return 0;
152 * File operations we support
154 static struct file_operations cpuid_fops = {
155 .owner = THIS_MODULE,
156 .llseek = cpuid_seek,
157 .read = cpuid_read,
158 .open = cpuid_open,
161 static int cpuid_class_simple_device_add(int i)
163 int err = 0;
164 struct class_device *class_err;
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;
172 static int __devinit cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
174 unsigned int cpu = (unsigned long)hcpu;
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;
184 return NOTIFY_OK;
187 static struct notifier_block cpuid_class_cpu_notifier =
189 .notifier_call = cpuid_class_cpu_callback,
192 static int __init cpuid_init(void)
194 int i, err = 0;
195 i = 0;
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;
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;
208 for_each_online_cpu(i) {
209 err = cpuid_class_simple_device_add(i);
210 if (err != 0)
211 goto out_class;
213 register_cpu_notifier(&cpuid_class_cpu_notifier);
215 err = 0;
216 goto out;
218 out_class:
219 i = 0;
220 for_each_online_cpu(i) {
221 class_simple_device_remove(MKDEV(CPUID_MAJOR, i));
223 class_simple_destroy(cpuid_class);
224 out_chrdev:
225 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
226 out:
227 return err;
230 static void __exit cpuid_exit(void)
232 int cpu = 0;
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);
241 module_init(cpuid_init);
242 module_exit(cpuid_exit);
244 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
245 MODULE_DESCRIPTION("x86 generic CPUID driver");
246 MODULE_LICENSE("GPL");