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 __cpuinit int cpuid_device_create(int cpu)
 138 {
 139         struct device *dev;
 140
 141         dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu),
 142                             "cpu%d", cpu);
 143         return IS_ERR(dev) ? PTR_ERR(dev) : 0;
 144 }
 145
 146 static void cpuid_device_destroy(int cpu)
 147 {
 148         device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 149 }
 150
 151 static int __cpuinit cpuid_class_cpu_callback(struct notifier_block *nfb,
 152                                               unsigned long action,
 153                                               void *hcpu)
 154 {
 155         unsigned int cpu = (unsigned long)hcpu;
 156         int err = 0;
 157
 158         switch (action) {
 159         case CPU_UP_PREPARE:
 160                 err = cpuid_device_create(cpu);
 161                 break;
 162         case CPU_UP_CANCELED:
 163         case CPU_DEAD:
 164                 cpuid_device_destroy(cpu);
 165                 break;
 166         case CPU_UP_CANCELED_FROZEN:
 167                 destroy_suspended_device(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 168                 break;
 169         }
 170         return err ? NOTIFY_BAD : NOTIFY_OK;
 171 }
 172
 173 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
 174 {
 175         .notifier_call = cpuid_class_cpu_callback,
 176 };
 177
 178 static int __init cpuid_init(void)
 179 {
 180         int i, err = 0;
 181         i = 0;
 182
 183         if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
 184                 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
 185                        CPUID_MAJOR);
 186                 err = -EBUSY;
 187                 goto out;
 188         }
 189         cpuid_class = class_create(THIS_MODULE, "cpuid");
 190         if (IS_ERR(cpuid_class)) {
 191                 err = PTR_ERR(cpuid_class);
 192                 goto out_chrdev;
 193         }
 194         for_each_online_cpu(i) {
 195                 err = cpuid_device_create(i);
 196                 if (err != 0)
 197                         goto out_class;
 198         }
 199         register_hotcpu_notifier(&cpuid_class_cpu_notifier);
 200
 201         err = 0;
 202         goto out;
 203
 204 out_class:
 205         i = 0;
 206         for_each_online_cpu(i) {
 207                 cpuid_device_destroy(i);
 208         }
 209         class_destroy(cpuid_class);
 210 out_chrdev:
 211         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 212 out:
 213         return err;
 214 }
 215
 216 static void __exit cpuid_exit(void)
 217 {
 218         int cpu = 0;
 219
 220         for_each_online_cpu(cpu)
 221                 cpuid_device_destroy(cpu);
 222         class_destroy(cpuid_class);
 223         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 224         unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
 225 }
 226
 227 module_init(cpuid_init);
 228 module_exit(cpuid_exit);
 229
 230 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 231 MODULE_DESCRIPTION("x86 generic CPUID driver");
 232 MODULE_LICENSE("GPL");