Commit | Line | Data |
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1da177e4 | 1 | /* ----------------------------------------------------------------------- * |
2b06ac86 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 MSR access device |
15 | * | |
16 | * This device is accessed by lseek() to the appropriate register number | |
17 | * and then read/write in chunks of 8 bytes. A larger size means multiple | |
18 | * reads or writes of the same register. | |
19 | * | |
20 | * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on | |
21 | * an SMP box will direct the access to CPU %d. | |
22 | */ | |
23 | ||
24 | #include <linux/module.h> | |
1da177e4 LT |
25 | |
26 | #include <linux/types.h> | |
27 | #include <linux/errno.h> | |
28 | #include <linux/fcntl.h> | |
29 | #include <linux/init.h> | |
30 | #include <linux/poll.h> | |
31 | #include <linux/smp.h> | |
32 | #include <linux/smp_lock.h> | |
33 | #include <linux/major.h> | |
34 | #include <linux/fs.h> | |
35 | #include <linux/device.h> | |
36 | #include <linux/cpu.h> | |
37 | #include <linux/notifier.h> | |
38 | ||
39 | #include <asm/processor.h> | |
40 | #include <asm/msr.h> | |
41 | #include <asm/uaccess.h> | |
42 | #include <asm/system.h> | |
43 | ||
8874b414 | 44 | static struct class *msr_class; |
1da177e4 | 45 | |
1da177e4 LT |
46 | static loff_t msr_seek(struct file *file, loff_t offset, int orig) |
47 | { | |
2b06ac86 PA |
48 | loff_t ret; |
49 | struct inode *inode = file->f_mapping->host; | |
1da177e4 | 50 | |
2b06ac86 | 51 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
52 | switch (orig) { |
53 | case 0: | |
54 | file->f_pos = offset; | |
55 | ret = file->f_pos; | |
56 | break; | |
57 | case 1: | |
58 | file->f_pos += offset; | |
59 | ret = file->f_pos; | |
2b06ac86 PA |
60 | break; |
61 | default: | |
62 | ret = -EINVAL; | |
1da177e4 | 63 | } |
2b06ac86 | 64 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
65 | return ret; |
66 | } | |
67 | ||
94a9fa41 PC |
68 | static ssize_t msr_read(struct file *file, char __user *buf, |
69 | size_t count, loff_t *ppos) | |
1da177e4 LT |
70 | { |
71 | u32 __user *tmp = (u32 __user *) buf; | |
72 | u32 data[2]; | |
1da177e4 | 73 | u32 reg = *ppos; |
aab4c5a5 | 74 | int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
75 | int err; |
76 | ||
77 | if (count % 8) | |
78 | return -EINVAL; /* Invalid chunk size */ | |
79 | ||
6926d570 | 80 | for (; count; count -= 8) { |
78a62d2c | 81 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
1da177e4 | 82 | if (err) |
78a62d2c | 83 | return -EIO; |
1da177e4 LT |
84 | if (copy_to_user(tmp, &data, 8)) |
85 | return -EFAULT; | |
86 | tmp += 2; | |
87 | } | |
88 | ||
89 | return ((char __user *)tmp) - buf; | |
90 | } | |
91 | ||
92 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
93 | size_t count, loff_t *ppos) | |
94 | { | |
95 | const u32 __user *tmp = (const u32 __user *)buf; | |
96 | u32 data[2]; | |
1da177e4 | 97 | u32 reg = *ppos; |
aab4c5a5 | 98 | int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
99 | int err; |
100 | ||
101 | if (count % 8) | |
102 | return -EINVAL; /* Invalid chunk size */ | |
103 | ||
f475ff35 | 104 | for (; count; count -= 8) { |
1da177e4 LT |
105 | if (copy_from_user(&data, tmp, 8)) |
106 | return -EFAULT; | |
78a62d2c | 107 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
1da177e4 | 108 | if (err) |
78a62d2c | 109 | return -EIO; |
1da177e4 LT |
110 | tmp += 2; |
111 | } | |
112 | ||
113 | return ((char __user *)tmp) - buf; | |
114 | } | |
115 | ||
116 | static int msr_open(struct inode *inode, struct file *file) | |
117 | { | |
aab4c5a5 | 118 | unsigned int cpu = iminor(file->f_path.dentry->d_inode); |
92cb7612 | 119 | struct cpuinfo_x86 *c = &cpu_data(cpu); |
5119e92e | 120 | int ret = 0; |
1da177e4 | 121 | |
5119e92e JC |
122 | lock_kernel(); |
123 | cpu = iminor(file->f_path.dentry->d_inode); | |
1da177e4 | 124 | |
5119e92e JC |
125 | if (cpu >= NR_CPUS || !cpu_online(cpu)) { |
126 | ret = -ENXIO; /* No such CPU */ | |
127 | goto out; | |
128 | } | |
129 | c = &cpu_data(cpu); | |
130 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
131 | ret = -EIO; /* MSR not supported */ | |
132 | out: | |
133 | unlock_kernel(); | |
1da177e4 LT |
134 | return 0; |
135 | } | |
136 | ||
137 | /* | |
138 | * File operations we support | |
139 | */ | |
5dfe4c96 | 140 | static const struct file_operations msr_fops = { |
1da177e4 LT |
141 | .owner = THIS_MODULE, |
142 | .llseek = msr_seek, | |
143 | .read = msr_read, | |
144 | .write = msr_write, | |
145 | .open = msr_open, | |
146 | }; | |
147 | ||
38048983 | 148 | static int __cpuinit msr_device_create(int cpu) |
1da177e4 | 149 | { |
a271aaf1 | 150 | struct device *dev; |
1da177e4 | 151 | |
3bfd49c8 GKH |
152 | dev = device_create_drvdata(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), |
153 | NULL, "msr%d", cpu); | |
881a841f AM |
154 | return IS_ERR(dev) ? PTR_ERR(dev) : 0; |
155 | } | |
156 | ||
157 | static void msr_device_destroy(int cpu) | |
158 | { | |
159 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
1da177e4 LT |
160 | } |
161 | ||
761c4bf8 | 162 | static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb, |
e09793bb | 163 | unsigned long action, void *hcpu) |
1da177e4 LT |
164 | { |
165 | unsigned int cpu = (unsigned long)hcpu; | |
881a841f | 166 | int err = 0; |
1da177e4 LT |
167 | |
168 | switch (action) { | |
881a841f | 169 | case CPU_UP_PREPARE: |
881a841f | 170 | err = msr_device_create(cpu); |
1da177e4 | 171 | break; |
881a841f | 172 | case CPU_UP_CANCELED: |
b844eba2 | 173 | case CPU_UP_CANCELED_FROZEN: |
1da177e4 | 174 | case CPU_DEAD: |
881a841f | 175 | msr_device_destroy(cpu); |
1da177e4 LT |
176 | break; |
177 | } | |
881a841f | 178 | return err ? NOTIFY_BAD : NOTIFY_OK; |
1da177e4 LT |
179 | } |
180 | ||
c72258c7 | 181 | static struct notifier_block __refdata msr_class_cpu_notifier = { |
1da177e4 LT |
182 | .notifier_call = msr_class_cpu_callback, |
183 | }; | |
184 | ||
185 | static int __init msr_init(void) | |
186 | { | |
187 | int i, err = 0; | |
188 | i = 0; | |
189 | ||
190 | if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) { | |
191 | printk(KERN_ERR "msr: unable to get major %d for msr\n", | |
192 | MSR_MAJOR); | |
193 | err = -EBUSY; | |
194 | goto out; | |
195 | } | |
8874b414 | 196 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
197 | if (IS_ERR(msr_class)) { |
198 | err = PTR_ERR(msr_class); | |
199 | goto out_chrdev; | |
200 | } | |
201 | for_each_online_cpu(i) { | |
a271aaf1 | 202 | err = msr_device_create(i); |
1da177e4 LT |
203 | if (err != 0) |
204 | goto out_class; | |
205 | } | |
e09793bb | 206 | register_hotcpu_notifier(&msr_class_cpu_notifier); |
1da177e4 LT |
207 | |
208 | err = 0; | |
209 | goto out; | |
210 | ||
211 | out_class: | |
212 | i = 0; | |
213 | for_each_online_cpu(i) | |
881a841f | 214 | msr_device_destroy(i); |
8874b414 | 215 | class_destroy(msr_class); |
1da177e4 LT |
216 | out_chrdev: |
217 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); | |
218 | out: | |
219 | return err; | |
220 | } | |
221 | ||
222 | static void __exit msr_exit(void) | |
223 | { | |
224 | int cpu = 0; | |
225 | for_each_online_cpu(cpu) | |
881a841f | 226 | msr_device_destroy(cpu); |
8874b414 | 227 | class_destroy(msr_class); |
1da177e4 | 228 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); |
e09793bb | 229 | unregister_hotcpu_notifier(&msr_class_cpu_notifier); |
1da177e4 LT |
230 | } |
231 | ||
232 | module_init(msr_init); | |
233 | module_exit(msr_exit) | |
234 | ||
235 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
236 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
237 | MODULE_LICENSE("GPL"); |