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
  46 struct cpuid_command {
  47   int cpu;
  48   u32 reg;
  49   u32 *data;
  50 };
  51
  52 static 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
  60 extern 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
  76 extern 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
  83 static 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
  97 static 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
 120 static 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  */
 136 static struct file_operations cpuid_fops = {
 137   owner:        THIS_MODULE,
 138   llseek:       cpuid_seek,
 139   read:         cpuid_read,
 140   open:         cpuid_open,
 141 };
 142
 143 int __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
 154 void __exit cpuid_exit(void)
 155 {
 156   unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 157 }
 158
 159 module_init(cpuid_init);
 160 module_exit(cpuid_exit)
 161
 162 EXPORT_NO_SYMBOLS;
 163
 164 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 165 MODULE_DESCRIPTION("x86 generic CPUID driver");