arch/x86/kernel/cpuid.c

   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  * 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  *
  20  * This driver uses /dev/cpu/%d/cpuid 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>
  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/major.h>
  33 #include <linux/fs.h>
  34 #include <linux/smp_lock.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
  44 static struct class *cpuid_class;
  45
  46 struct cpuid_command {
  47         u32 reg;
  48         u32 *data;
  49 };
  50
  51 static void cpuid_smp_cpuid(void *cmd_block)
  52 {
  53         struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
  54
  55         cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
  56                       &cmd->data[3]);
  57 }
  58
  59 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
  60 {
  61         struct cpuid_command cmd;
  62
  63         cmd.reg = reg;
  64         cmd.data = data;
  65
  66         smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1);
  67 }
  68
  69 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
  70 {
  71         loff_t ret;
  72
  73         lock_kernel();
  74
  75         switch (orig) {
  76         case 0:
  77                 file->f_pos = offset;
  78                 ret = file->f_pos;
  79                 break;
  80         case 1:
  81                 file->f_pos += offset;
  82                 ret = file->f_pos;
  83                 break;
  84         default:
  85                 ret = -EINVAL;
  86         }
  87
  88         unlock_kernel();
  89         return ret;
  90 }
  91
  92 static ssize_t cpuid_read(struct file *file, char __user *buf,
  93                           size_t count, loff_t * ppos)
  94 {
  95         char __user *tmp = buf;
  96         u32 data[4];
  97         u32 reg = *ppos;
  98         int cpu = iminor(file->f_path.dentry->d_inode);
  99
 100         if (count % 16)
 101                 return -EINVAL; /* Invalid chunk size */
 102
 103         for (; count; count -= 16) {
 104                 do_cpuid(cpu, reg, data);
 105                 if (copy_to_user(tmp, &data, 16))
 106                         return -EFAULT;
 107                 tmp += 16;
 108                 *ppos = reg++;
 109         }
 110
 111         return tmp - buf;
 112 }
 113
 114 static int cpuid_open(struct inode *inode, struct file *file)
 115 {
 116         unsigned int cpu = iminor(file->f_path.dentry->d_inode);
 117         struct cpuinfo_x86 *c = &(cpu_data)[cpu];
 118
 119         if (cpu >= NR_CPUS || !cpu_online(cpu))
 120                 return -ENXIO;  /* No such CPU */
 121         if (c->cpuid_level < 0)
 122                 return -EIO;    /* CPUID not supported */
 123
 124         return 0;
 125 }
 126
 127 /*
 128  * File operations we support
 129  */
 130 static const struct file_operations cpuid_fops = {
 131         .owner = THIS_MODULE,
 132         .llseek = cpuid_seek,
 133         .read = cpuid_read,
 134         .open = cpuid_open,
 135 };
 136
 137 static int __cpuinit cpuid_device_create(int i)
 138 {
 139         int err = 0;
 140         struct device *dev;
 141
 142         dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i);
 143         if (IS_ERR(dev))
 144                 err = PTR_ERR(dev);
 145         return err;
 146 }
 147
 148 static int __cpuinit cpuid_class_cpu_callback(struct notifier_block *nfb,
 149                                               unsigned long action,
 150                                               void *hcpu)
 151 {
 152         unsigned int cpu = (unsigned long)hcpu;
 153
 154         switch (action) {
 155         case CPU_ONLINE:
 156         case CPU_ONLINE_FROZEN:
 157                 cpuid_device_create(cpu);
 158                 break;
 159         case CPU_DEAD:
 160         case CPU_DEAD_FROZEN:
 161                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 162                 break;
 163         }
 164         return NOTIFY_OK;
 165 }
 166
 167 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
 168 {
 169         .notifier_call = cpuid_class_cpu_callback,
 170 };
 171
 172 static int __init cpuid_init(void)
 173 {
 174         int i, err = 0;
 175         i = 0;
 176
 177         if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
 178                 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
 179                        CPUID_MAJOR);
 180                 err = -EBUSY;
 181                 goto out;
 182         }
 183         cpuid_class = class_create(THIS_MODULE, "cpuid");
 184         if (IS_ERR(cpuid_class)) {
 185                 err = PTR_ERR(cpuid_class);
 186                 goto out_chrdev;
 187         }
 188         for_each_online_cpu(i) {
 189                 err = cpuid_device_create(i);
 190                 if (err != 0)
 191                         goto out_class;
 192         }
 193         register_hotcpu_notifier(&cpuid_class_cpu_notifier);
 194
 195         err = 0;
 196         goto out;
 197
 198 out_class:
 199         i = 0;
 200         for_each_online_cpu(i) {
 201                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i));
 202         }
 203         class_destroy(cpuid_class);
 204 out_chrdev:
 205         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 206 out:
 207         return err;
 208 }
 209
 210 static void __exit cpuid_exit(void)
 211 {
 212         int cpu = 0;
 213
 214         for_each_online_cpu(cpu)
 215                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 216         class_destroy(cpuid_class);
 217         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 218         unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
 219 }
 220
 221 module_init(cpuid_init);
 222 module_exit(cpuid_exit);
 223
 224 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 225 MODULE_DESCRIPTION("x86 generic CPUID driver");
 226 MODULE_LICENSE("GPL");