Commit | Line | Data |
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1da177e4 | 1 | /* ----------------------------------------------------------------------- * |
2347d933 PA |
2 | * |
3 | * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved | |
1da177e4 LT |
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 | /* | |
1da177e4 LT |
14 | * x86 CPUID access device |
15 | * | |
16 | * This device is accessed by lseek() to the appropriate CPUID level | |
17 | * and then read in chunks of 16 bytes. A larger size means multiple | |
18 | * reads of consecutive levels. | |
19 | * | |
2347d933 PA |
20 | * The lower 32 bits of the file position is used as the incoming %eax, |
21 | * and the upper 32 bits of the file position as the incoming %ecx, | |
22 | * the latter intended for "counting" eax levels like eax=4. | |
23 | * | |
1da177e4 LT |
24 | * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on |
25 | * an SMP box will direct the access to CPU %d. | |
26 | */ | |
27 | ||
28 | #include <linux/module.h> | |
1da177e4 LT |
29 | |
30 | #include <linux/types.h> | |
31 | #include <linux/errno.h> | |
32 | #include <linux/fcntl.h> | |
33 | #include <linux/init.h> | |
34 | #include <linux/poll.h> | |
35 | #include <linux/smp.h> | |
36 | #include <linux/major.h> | |
37 | #include <linux/fs.h> | |
1da177e4 LT |
38 | #include <linux/device.h> |
39 | #include <linux/cpu.h> | |
40 | #include <linux/notifier.h> | |
f634fa94 | 41 | #include <linux/uaccess.h> |
5a0e3ad6 | 42 | #include <linux/gfp.h> |
1da177e4 LT |
43 | |
44 | #include <asm/processor.h> | |
45 | #include <asm/msr.h> | |
1da177e4 | 46 | |
8874b414 | 47 | static struct class *cpuid_class; |
ee92be9b | 48 | static enum cpuhp_state cpuhp_cpuid_state; |
1da177e4 | 49 | |
1da177e4 LT |
50 | static void cpuid_smp_cpuid(void *cmd_block) |
51 | { | |
2347d933 | 52 | struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block; |
1da177e4 | 53 | |
2347d933 PA |
54 | cpuid_count(cmd->eax, cmd->ecx, |
55 | &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx); | |
1da177e4 LT |
56 | } |
57 | ||
1da177e4 | 58 | static ssize_t cpuid_read(struct file *file, char __user *buf, |
f634fa94 | 59 | size_t count, loff_t *ppos) |
1da177e4 LT |
60 | { |
61 | char __user *tmp = buf; | |
2347d933 | 62 | struct cpuid_regs cmd; |
496ad9aa | 63 | int cpu = iminor(file_inode(file)); |
2347d933 | 64 | u64 pos = *ppos; |
9ea2b82e PA |
65 | ssize_t bytes = 0; |
66 | int err = 0; | |
1da177e4 LT |
67 | |
68 | if (count % 16) | |
69 | return -EINVAL; /* Invalid chunk size */ | |
70 | ||
6b7f430e | 71 | for (; count; count -= 16) { |
2347d933 PA |
72 | cmd.eax = pos; |
73 | cmd.ecx = pos >> 32; | |
4b46ca70 PA |
74 | err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1); |
75 | if (err) | |
9ea2b82e PA |
76 | break; |
77 | if (copy_to_user(tmp, &cmd, 16)) { | |
78 | err = -EFAULT; | |
79 | break; | |
80 | } | |
1da177e4 | 81 | tmp += 16; |
9ea2b82e | 82 | bytes += 16; |
2347d933 | 83 | *ppos = ++pos; |
1da177e4 LT |
84 | } |
85 | ||
9ea2b82e | 86 | return bytes ? bytes : err; |
1da177e4 LT |
87 | } |
88 | ||
89 | static int cpuid_open(struct inode *inode, struct file *file) | |
90 | { | |
5119e92e JC |
91 | unsigned int cpu; |
92 | struct cpuinfo_x86 *c; | |
5119e92e | 93 | |
496ad9aa | 94 | cpu = iminor(file_inode(file)); |
5a943617 JK |
95 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
96 | return -ENXIO; /* No such CPU */ | |
97 | ||
5119e92e | 98 | c = &cpu_data(cpu); |
1da177e4 | 99 | if (c->cpuid_level < 0) |
5a943617 JK |
100 | return -EIO; /* CPUID not supported */ |
101 | ||
102 | return 0; | |
1da177e4 LT |
103 | } |
104 | ||
105 | /* | |
106 | * File operations we support | |
107 | */ | |
5dfe4c96 | 108 | static const struct file_operations cpuid_fops = { |
1da177e4 | 109 | .owner = THIS_MODULE, |
b25472f9 | 110 | .llseek = no_seek_end_llseek, |
1da177e4 LT |
111 | .read = cpuid_read, |
112 | .open = cpuid_open, | |
113 | }; | |
114 | ||
8c07b494 | 115 | static int cpuid_device_create(unsigned int cpu) |
1da177e4 | 116 | { |
07accdc1 | 117 | struct device *dev; |
1da177e4 | 118 | |
a9b12619 GKH |
119 | dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL, |
120 | "cpu%d", cpu); | |
cbda45a2 | 121 | return PTR_ERR_OR_ZERO(dev); |
1f503e77 AM |
122 | } |
123 | ||
8c07b494 | 124 | static int cpuid_device_destroy(unsigned int cpu) |
1f503e77 AM |
125 | { |
126 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); | |
8c07b494 | 127 | return 0; |
1da177e4 LT |
128 | } |
129 | ||
2c9ede55 | 130 | static char *cpuid_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
131 | { |
132 | return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt)); | |
133 | } | |
134 | ||
1da177e4 LT |
135 | static int __init cpuid_init(void) |
136 | { | |
8c07b494 | 137 | int err; |
1da177e4 | 138 | |
0b962d47 PA |
139 | if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS, |
140 | "cpu/cpuid", &cpuid_fops)) { | |
1da177e4 LT |
141 | printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", |
142 | CPUID_MAJOR); | |
8c07b494 | 143 | return -EBUSY; |
1da177e4 | 144 | } |
8874b414 | 145 | cpuid_class = class_create(THIS_MODULE, "cpuid"); |
1da177e4 LT |
146 | if (IS_ERR(cpuid_class)) { |
147 | err = PTR_ERR(cpuid_class); | |
148 | goto out_chrdev; | |
149 | } | |
e454cea2 | 150 | cpuid_class->devnode = cpuid_devnode; |
4b660b38 | 151 | |
ee92be9b | 152 | err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online", |
8c07b494 | 153 | cpuid_device_create, cpuid_device_destroy); |
ee92be9b | 154 | if (err < 0) |
8c07b494 | 155 | goto out_class; |
1da177e4 | 156 | |
ee92be9b | 157 | cpuhp_cpuid_state = err; |
8c07b494 | 158 | return 0; |
1da177e4 LT |
159 | |
160 | out_class: | |
8874b414 | 161 | class_destroy(cpuid_class); |
1da177e4 | 162 | out_chrdev: |
0b962d47 | 163 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
1da177e4 LT |
164 | return err; |
165 | } | |
ee92be9b | 166 | module_init(cpuid_init); |
1da177e4 LT |
167 | |
168 | static void __exit cpuid_exit(void) | |
169 | { | |
ee92be9b | 170 | cpuhp_remove_state(cpuhp_cpuid_state); |
8874b414 | 171 | class_destroy(cpuid_class); |
da482474 | 172 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
1da177e4 | 173 | } |
1da177e4 LT |
174 | module_exit(cpuid_exit); |
175 | ||
176 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
177 | MODULE_DESCRIPTION("x86 generic CPUID driver"); | |
178 | MODULE_LICENSE("GPL"); |