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/arch/i386/kernel/cpuid.c

https://bitbucket.org/evzijst/gittest
C | 246 lines | 181 code | 39 blank | 26 comment | 18 complexity | 848e93eab2157f92bc1ac8495dfe47ae MD5 | raw file
  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");