LXR linux-old/arch/i386/kernel/cpuid.c

   1#ident "$Id$"
   2/* ----------------------------------------------------------------------- *
   3 *   
   4 *   Copyright 2000 H. Peter Anvin - All Rights Reserved
   5 *
   6 *   This program is free software; you can redistribute it and/or modify
   7 *   it under the terms of the GNU General Public License as published by
   8 *   the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
   9 *   USA; either version 2 of the License, or (at your option) any later
  10 *   version; incorporated herein by reference.
  11 *
  12 * ----------------------------------------------------------------------- */
  13
  14
  15/*
  16 * cpuid.c
  17 *
  18 * x86 CPUID access device
  19 *
  20 * This device is accessed by lseek() to the appropriate CPUID level
  21 * and then read in chunks of 16 bytes.  A larger size means multiple
  22 * reads of consecutive levels.
  23 *
  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>
  29#include <linux/config.h>
  30
  31#include <linux/types.h>
  32#include <linux/errno.h>
  33#include <linux/fcntl.h>
  34#include <linux/init.h>
  35#include <linux/poll.h>
  36#include <linux/smp.h>
  37#include <linux/major.h>
  38
  39#include <asm/processor.h>
  40#include <asm/msr.h>
  41#include <asm/uaccess.h>
  42#include <asm/system.h>
  43
  44#ifdef CONFIG_SMP
  45
  46struct cpuid_command {
  47  int cpu;
  48  u32 reg;
  49  u32 *data;
  50};
  51
  52static void cpuid_smp_cpuid(void *cmd_block)
  53{
  54  struct cpuid_command *cmd = (struct cpuid_command *) cmd_block;
  55  
  56  if ( cmd->cpu == smp_processor_id() )
  57    cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2], &cmd->data[3]);
  58}
  59
  60static inline void do_cpuid(int cpu, u32 reg, u32 *data)
  61{
  62  struct cpuid_command cmd;
  63  
  64  if ( cpu == smp_processor_id() ) {
  65    cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  66  } else {
  67    cmd.cpu  = cpu;
  68    cmd.reg  = reg;
  69    cmd.data = data;
  70    
  71    smp_call_function(cpuid_smp_cpuid, &cmd, 1, 1);
  72  }
  73}
  74#else /* ! CONFIG_SMP */
  75
  76static inline void do_cpuid(int cpu, u32 reg, u32 *data)
  77{
  78  cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  79}
  80
  81#endif /* ! CONFIG_SMP */
  82
  83static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
  84{
  85  switch (orig) {
  86  case 0:
  87    file->f_pos = offset;
  88    return file->f_pos;
  89  case 1:
  90    file->f_pos += offset;
  91    return file->f_pos;
  92  default:
  93    return -EINVAL;     /* SEEK_END not supported */
  94  }
  95}
  96
  97static ssize_t cpuid_read(struct file * file, char * buf,
  98                        size_t count, loff_t *ppos)
  99{
 100  u32 *tmp = (u32 *)buf;
 101  u32 data[4];
 102  size_t rv;
 103  u32 reg = *ppos;
 104  int cpu = MINOR(file->f_dentry->d_inode->i_rdev);
 105  
 106  if ( count % 16 )
 107    return -EINVAL; /* Invalid chunk size */
 108  
 109  for ( rv = 0 ; count ; count -= 16 ) {
 110    do_cpuid(cpu, reg, data);
 111    if ( copy_to_user(tmp,&data,16) )
 112      return -EFAULT;
 113    tmp += 4;
 114    *ppos = reg++;
 115  }
 116  
 117  return ((char *)tmp) - buf;
 118}
 119
 120static int cpuid_open(struct inode *inode, struct file *file)
 121{
 122  int cpu = MINOR(file->f_dentry->d_inode->i_rdev);
 123  struct cpuinfo_x86 *c = &(cpu_data)[cpu];
 124
 125  if ( !(cpu_online_map & (1UL << cpu)) )
 126    return -ENXIO;              /* No such CPU */
 127  if ( c->cpuid_level < 0 )
 128    return -EIO;                /* CPUID not supported */
 129  
 130  return 0;
 131}
 132
 133/*
 134 * File operations we support
 135 */
 136static struct file_operations cpuid_fops = {
 137  owner:        THIS_MODULE,
 138  llseek:       cpuid_seek,
 139  read:         cpuid_read,
 140  open:         cpuid_open,
 141};
 142
 143int __init cpuid_init(void)
 144{
 145  if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
 146    printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
 147           CPUID_MAJOR);
 148    return -EBUSY;
 149  }
 150
 151  return 0;
 152}
 153
 154void __exit cpuid_exit(void)
 155{
 156  unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 157}
 158
 159module_init(cpuid_init);
 160module_exit(cpuid_exit)
 161
 162EXPORT_NO_SYMBOLS;
 163
 164MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 165MODULE_DESCRIPTION("x86 generic CPUID driver");
 166MODULE_LICENSE("GPL");
 167