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1da177e4 LT |
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 | /* | |
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 | { | |
48 | loff_t ret = -EINVAL; | |
49 | ||
50 | lock_kernel(); | |
51 | switch (orig) { | |
52 | case 0: | |
53 | file->f_pos = offset; | |
54 | ret = file->f_pos; | |
55 | break; | |
56 | case 1: | |
57 | file->f_pos += offset; | |
58 | ret = file->f_pos; | |
59 | } | |
60 | unlock_kernel(); | |
61 | return ret; | |
62 | } | |
63 | ||
64 | static ssize_t msr_read(struct file *file, char __user * buf, | |
65 | size_t count, loff_t * ppos) | |
66 | { | |
67 | u32 __user *tmp = (u32 __user *) buf; | |
68 | u32 data[2]; | |
1da177e4 | 69 | u32 reg = *ppos; |
aab4c5a5 | 70 | int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
71 | int err; |
72 | ||
73 | if (count % 8) | |
74 | return -EINVAL; /* Invalid chunk size */ | |
75 | ||
6926d570 | 76 | for (; count; count -= 8) { |
78a62d2c | 77 | err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]); |
1da177e4 | 78 | if (err) |
78a62d2c | 79 | return -EIO; |
1da177e4 LT |
80 | if (copy_to_user(tmp, &data, 8)) |
81 | return -EFAULT; | |
82 | tmp += 2; | |
83 | } | |
84 | ||
85 | return ((char __user *)tmp) - buf; | |
86 | } | |
87 | ||
88 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
89 | size_t count, loff_t *ppos) | |
90 | { | |
91 | const u32 __user *tmp = (const u32 __user *)buf; | |
92 | u32 data[2]; | |
1da177e4 | 93 | u32 reg = *ppos; |
aab4c5a5 | 94 | int cpu = iminor(file->f_path.dentry->d_inode); |
1da177e4 LT |
95 | int err; |
96 | ||
97 | if (count % 8) | |
98 | return -EINVAL; /* Invalid chunk size */ | |
99 | ||
f475ff35 | 100 | for (; count; count -= 8) { |
1da177e4 LT |
101 | if (copy_from_user(&data, tmp, 8)) |
102 | return -EFAULT; | |
78a62d2c | 103 | err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); |
1da177e4 | 104 | if (err) |
78a62d2c | 105 | return -EIO; |
1da177e4 LT |
106 | tmp += 2; |
107 | } | |
108 | ||
109 | return ((char __user *)tmp) - buf; | |
110 | } | |
111 | ||
112 | static int msr_open(struct inode *inode, struct file *file) | |
113 | { | |
aab4c5a5 | 114 | unsigned int cpu = iminor(file->f_path.dentry->d_inode); |
92cb7612 | 115 | struct cpuinfo_x86 *c = &cpu_data(cpu); |
1da177e4 LT |
116 | |
117 | if (cpu >= NR_CPUS || !cpu_online(cpu)) | |
118 | return -ENXIO; /* No such CPU */ | |
119 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
120 | return -EIO; /* MSR not supported */ | |
121 | ||
122 | return 0; | |
123 | } | |
124 | ||
125 | /* | |
126 | * File operations we support | |
127 | */ | |
5dfe4c96 | 128 | static const struct file_operations msr_fops = { |
1da177e4 LT |
129 | .owner = THIS_MODULE, |
130 | .llseek = msr_seek, | |
131 | .read = msr_read, | |
132 | .write = msr_write, | |
133 | .open = msr_open, | |
134 | }; | |
135 | ||
38048983 | 136 | static int __cpuinit msr_device_create(int cpu) |
1da177e4 | 137 | { |
a271aaf1 | 138 | struct device *dev; |
1da177e4 | 139 | |
881a841f AM |
140 | dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), |
141 | "msr%d", cpu); | |
142 | return IS_ERR(dev) ? PTR_ERR(dev) : 0; | |
143 | } | |
144 | ||
145 | static void msr_device_destroy(int cpu) | |
146 | { | |
147 | device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
1da177e4 LT |
148 | } |
149 | ||
761c4bf8 | 150 | static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb, |
e09793bb | 151 | unsigned long action, void *hcpu) |
1da177e4 LT |
152 | { |
153 | unsigned int cpu = (unsigned long)hcpu; | |
881a841f | 154 | int err = 0; |
1da177e4 LT |
155 | |
156 | switch (action) { | |
881a841f | 157 | case CPU_UP_PREPARE: |
881a841f | 158 | err = msr_device_create(cpu); |
1da177e4 | 159 | break; |
881a841f | 160 | case CPU_UP_CANCELED: |
1da177e4 | 161 | case CPU_DEAD: |
881a841f | 162 | msr_device_destroy(cpu); |
1da177e4 | 163 | break; |
775b64d2 RW |
164 | case CPU_UP_CANCELED_FROZEN: |
165 | destroy_suspended_device(msr_class, MKDEV(MSR_MAJOR, cpu)); | |
166 | break; | |
1da177e4 | 167 | } |
881a841f | 168 | return err ? NOTIFY_BAD : NOTIFY_OK; |
1da177e4 LT |
169 | } |
170 | ||
881a841f | 171 | static struct notifier_block __cpuinitdata msr_class_cpu_notifier = { |
1da177e4 LT |
172 | .notifier_call = msr_class_cpu_callback, |
173 | }; | |
174 | ||
175 | static int __init msr_init(void) | |
176 | { | |
177 | int i, err = 0; | |
178 | i = 0; | |
179 | ||
180 | if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) { | |
181 | printk(KERN_ERR "msr: unable to get major %d for msr\n", | |
182 | MSR_MAJOR); | |
183 | err = -EBUSY; | |
184 | goto out; | |
185 | } | |
8874b414 | 186 | msr_class = class_create(THIS_MODULE, "msr"); |
1da177e4 LT |
187 | if (IS_ERR(msr_class)) { |
188 | err = PTR_ERR(msr_class); | |
189 | goto out_chrdev; | |
190 | } | |
191 | for_each_online_cpu(i) { | |
a271aaf1 | 192 | err = msr_device_create(i); |
1da177e4 LT |
193 | if (err != 0) |
194 | goto out_class; | |
195 | } | |
e09793bb | 196 | register_hotcpu_notifier(&msr_class_cpu_notifier); |
1da177e4 LT |
197 | |
198 | err = 0; | |
199 | goto out; | |
200 | ||
201 | out_class: | |
202 | i = 0; | |
203 | for_each_online_cpu(i) | |
881a841f | 204 | msr_device_destroy(i); |
8874b414 | 205 | class_destroy(msr_class); |
1da177e4 LT |
206 | out_chrdev: |
207 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); | |
208 | out: | |
209 | return err; | |
210 | } | |
211 | ||
212 | static void __exit msr_exit(void) | |
213 | { | |
214 | int cpu = 0; | |
215 | for_each_online_cpu(cpu) | |
881a841f | 216 | msr_device_destroy(cpu); |
8874b414 | 217 | class_destroy(msr_class); |
1da177e4 | 218 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); |
e09793bb | 219 | unregister_hotcpu_notifier(&msr_class_cpu_notifier); |
1da177e4 LT |
220 | } |
221 | ||
222 | module_init(msr_init); | |
223 | module_exit(msr_exit) | |
224 | ||
225 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
226 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
227 | MODULE_LICENSE("GPL"); |