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
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>
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
46static struct class *cpuid_class;
47
48#ifdef CONFIG_SMP
49
50struct cpuid_command {
51	u32 reg;
52	u32 *data;
53};
54
55static void cpuid_smp_cpuid(void *cmd_block)
56{
57	struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
58
59	cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
60		      &cmd->data[3]);
61}
62
63static 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 {
71		cmd.reg = reg;
72		cmd.data = data;
73
74		smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1);
75	}
76	preempt_enable();
77}
78#else				/* ! CONFIG_SMP */
79
80static 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
87static 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
110static 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];
115	u32 reg = *ppos;
116	int cpu = iminor(file->f_path.dentry->d_inode);
117
118	if (count % 16)
119		return -EINVAL;	/* Invalid chunk size */
120
121	for (; count; count -= 16) {
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
132static int cpuid_open(struct inode *inode, struct file *file)
133{
134	unsigned int cpu = iminor(file->f_path.dentry->d_inode);
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 */
148static const struct file_operations cpuid_fops = {
149	.owner = THIS_MODULE,
150	.llseek = cpuid_seek,
151	.read = cpuid_read,
152	.open = cpuid_open,
153};
154
155static int cpuid_device_create(int i)
156{
157	int err = 0;
158	struct device *dev;
159
160	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i);
161	if (IS_ERR(dev))
162		err = PTR_ERR(dev);
163	return err;
164}
165
166static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
167{
168	unsigned int cpu = (unsigned long)hcpu;
169
170	switch (action) {
171	case CPU_ONLINE:
172	case CPU_ONLINE_FROZEN:
173		cpuid_device_create(cpu);
174		break;
175	case CPU_DEAD:
176	case CPU_DEAD_FROZEN:
177		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
178		break;
179	}
180	return NOTIFY_OK;
181}
182
183static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
184{
185	.notifier_call = cpuid_class_cpu_callback,
186};
187
188static int __init cpuid_init(void)
189{
190	int i, err = 0;
191	i = 0;
192
193	if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
194		printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
195		       CPUID_MAJOR);
196		err = -EBUSY;
197		goto out;
198	}
199	cpuid_class = class_create(THIS_MODULE, "cpuid");
200	if (IS_ERR(cpuid_class)) {
201		err = PTR_ERR(cpuid_class);
202		goto out_chrdev;
203	}
204	for_each_online_cpu(i) {
205		err = cpuid_device_create(i);
206		if (err != 0)
207			goto out_class;
208	}
209	register_hotcpu_notifier(&cpuid_class_cpu_notifier);
210
211	err = 0;
212	goto out;
213
214out_class:
215	i = 0;
216	for_each_online_cpu(i) {
217		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i));
218	}
219	class_destroy(cpuid_class);
220out_chrdev:
221	unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
222out:
223	return err;
224}
225
226static void __exit cpuid_exit(void)
227{
228	int cpu = 0;
229
230	for_each_online_cpu(cpu)
231		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
232	class_destroy(cpuid_class);
233	unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
234	unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
235}
236
237module_init(cpuid_init);
238module_exit(cpuid_exit);
239
240MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
241MODULE_DESCRIPTION("x86 generic CPUID driver");
242MODULE_LICENSE("GPL");
243