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> |
67bbd7a8 | 43 | #include <linux/completion.h> |
1da177e4 LT |
44 | |
45 | #include <asm/processor.h> | |
46 | #include <asm/msr.h> | |
1da177e4 | 47 | |
8874b414 | 48 | static struct class *cpuid_class; |
ee92be9b | 49 | static enum cpuhp_state cpuhp_cpuid_state; |
1da177e4 | 50 | |
67bbd7a8 ED |
51 | struct cpuid_regs_done { |
52 | struct cpuid_regs regs; | |
53 | struct completion done; | |
54 | }; | |
55 | ||
1da177e4 LT |
56 | static void cpuid_smp_cpuid(void *cmd_block) |
57 | { | |
67bbd7a8 ED |
58 | struct cpuid_regs_done *cmd = cmd_block; |
59 | ||
60 | cpuid_count(cmd->regs.eax, cmd->regs.ecx, | |
61 | &cmd->regs.eax, &cmd->regs.ebx, | |
62 | &cmd->regs.ecx, &cmd->regs.edx); | |
1da177e4 | 63 | |
67bbd7a8 | 64 | complete(&cmd->done); |
1da177e4 LT |
65 | } |
66 | ||
1da177e4 | 67 | static ssize_t cpuid_read(struct file *file, char __user *buf, |
f634fa94 | 68 | size_t count, loff_t *ppos) |
1da177e4 LT |
69 | { |
70 | char __user *tmp = buf; | |
67bbd7a8 | 71 | struct cpuid_regs_done cmd; |
496ad9aa | 72 | int cpu = iminor(file_inode(file)); |
2347d933 | 73 | u64 pos = *ppos; |
9ea2b82e PA |
74 | ssize_t bytes = 0; |
75 | int err = 0; | |
1da177e4 LT |
76 | |
77 | if (count % 16) | |
78 | return -EINVAL; /* Invalid chunk size */ | |
79 | ||
67bbd7a8 | 80 | init_completion(&cmd.done); |
6b7f430e | 81 | for (; count; count -= 16) { |
67bbd7a8 ED |
82 | call_single_data_t csd = { |
83 | .func = cpuid_smp_cpuid, | |
84 | .info = &cmd, | |
85 | }; | |
86 | ||
87 | cmd.regs.eax = pos; | |
88 | cmd.regs.ecx = pos >> 32; | |
89 | ||
90 | err = smp_call_function_single_async(cpu, &csd); | |
4b46ca70 | 91 | if (err) |
9ea2b82e | 92 | break; |
67bbd7a8 ED |
93 | wait_for_completion(&cmd.done); |
94 | if (copy_to_user(tmp, &cmd.regs, 16)) { | |
9ea2b82e PA |
95 | err = -EFAULT; |
96 | break; | |
97 | } | |
1da177e4 | 98 | tmp += 16; |
9ea2b82e | 99 | bytes += 16; |
2347d933 | 100 | *ppos = ++pos; |
67bbd7a8 | 101 | reinit_completion(&cmd.done); |
1da177e4 LT |
102 | } |
103 | ||
9ea2b82e | 104 | return bytes ? bytes : err; |
1da177e4 LT |
105 | } |
106 | ||
107 | static int cpuid_open(struct inode *inode, struct file *file) | |
108 | { | |
5119e92e JC |
109 | unsigned int cpu; |
110 | struct cpuinfo_x86 *c; | |
5119e92e | 111 | |
496ad9aa | 112 | cpu = iminor(file_inode(file)); |
5a943617 JK |
113 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
114 | return -ENXIO; /* No such CPU */ | |
115 | ||
5119e92e | 116 | c = &cpu_data(cpu); |
1da177e4 | 117 | if (c->cpuid_level < 0) |
5a943617 JK |
118 | return -EIO; /* CPUID not supported */ |
119 | ||
120 | return 0; | |
1da177e4 LT |
121 | } |
122 | ||
123 | /* | |
124 | * File operations we support | |
125 | */ | |
5dfe4c96 | 126 | static const struct file_operations cpuid_fops = { |
1da177e4 | 127 | .owner = THIS_MODULE, |
b25472f9 | 128 | .llseek = no_seek_end_llseek, |
1da177e4 LT |
129 | .read = cpuid_read, |
130 | .open = cpuid_open, | |
131 | }; | |
132 | ||
8c07b494 | 133 | static int cpuid_device_create(unsigned int cpu) |
1da177e4 | 134 | { |
07accdc1 | 135 | struct device *dev; |
1da177e4 | 136 | |
a9b12619 GKH |
137 | dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL, |
138 | "cpu%d", cpu); | |
cbda45a2 | 139 | return PTR_ERR_OR_ZERO(dev); |
1f503e77 AM |
140 | } |
141 | ||
8c07b494 | 142 | static int cpuid_device_destroy(unsigned int cpu) |
1f503e77 AM |
143 | { |
144 | device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); | |
8c07b494 | 145 | return 0; |
1da177e4 LT |
146 | } |
147 | ||
2c9ede55 | 148 | static char *cpuid_devnode(struct device *dev, umode_t *mode) |
07e9bb8e KS |
149 | { |
150 | return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt)); | |
151 | } | |
152 | ||
1da177e4 LT |
153 | static int __init cpuid_init(void) |
154 | { | |
8c07b494 | 155 | int err; |
1da177e4 | 156 | |
0b962d47 PA |
157 | if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS, |
158 | "cpu/cpuid", &cpuid_fops)) { | |
1da177e4 LT |
159 | printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", |
160 | CPUID_MAJOR); | |
8c07b494 | 161 | return -EBUSY; |
1da177e4 | 162 | } |
8874b414 | 163 | cpuid_class = class_create(THIS_MODULE, "cpuid"); |
1da177e4 LT |
164 | if (IS_ERR(cpuid_class)) { |
165 | err = PTR_ERR(cpuid_class); | |
166 | goto out_chrdev; | |
167 | } | |
e454cea2 | 168 | cpuid_class->devnode = cpuid_devnode; |
4b660b38 | 169 | |
ee92be9b | 170 | err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online", |
8c07b494 | 171 | cpuid_device_create, cpuid_device_destroy); |
ee92be9b | 172 | if (err < 0) |
8c07b494 | 173 | goto out_class; |
1da177e4 | 174 | |
ee92be9b | 175 | cpuhp_cpuid_state = err; |
8c07b494 | 176 | return 0; |
1da177e4 LT |
177 | |
178 | out_class: | |
8874b414 | 179 | class_destroy(cpuid_class); |
1da177e4 | 180 | out_chrdev: |
0b962d47 | 181 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
1da177e4 LT |
182 | return err; |
183 | } | |
ee92be9b | 184 | module_init(cpuid_init); |
1da177e4 LT |
185 | |
186 | static void __exit cpuid_exit(void) | |
187 | { | |
ee92be9b | 188 | cpuhp_remove_state(cpuhp_cpuid_state); |
8874b414 | 189 | class_destroy(cpuid_class); |
da482474 | 190 | __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); |
1da177e4 | 191 | } |
1da177e4 LT |
192 | module_exit(cpuid_exit); |
193 | ||
194 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
195 | MODULE_DESCRIPTION("x86 generic CPUID driver"); | |
196 | MODULE_LICENSE("GPL"); |