arch/i386/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  * cpuid.c
  15  *
  16  * x86 CPUID access device
  17  *
  18  * This device is accessed by lseek() to the appropriate CPUID level
  19  * and then read in chunks of 16 bytes.  A larger size means multiple
  20  * reads of consecutive levels.
  21  *
  22  * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on
  23  * an SMP box will direct the access to CPU %d.
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/config.h>
  28
  29 #include <linux/types.h>
  30 #include <linux/errno.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/init.h>
  33 #include <linux/poll.h>
  34 #include <linux/smp.h>
  35 #include <linux/major.h>
  36 #include <linux/fs.h>
  37 #include <linux/smp_lock.h>
  38 #include <linux/fs.h>
  39 #include <linux/device.h>
  40 #include <linux/cpu.h>
  41 #include <linux/notifier.h>
  42
  43 #include <asm/processor.h>
  44 #include <asm/msr.h>
  45 #include <asm/uaccess.h>
  46 #include <asm/system.h>
  47
  48 static struct class_simple *cpuid_class;
  49
  50 #ifdef CONFIG_SMP
  51
  52 struct cpuid_command {
  53         int cpu;
  54         u32 reg;
  55         u32 *data;
  56 };
  57
  58 static void cpuid_smp_cpuid(void *cmd_block)
  59 {
  60         struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
  61
  62         if (cmd->cpu == smp_processor_id())
  63                 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
  64                       &cmd->data[3]);
  65 }
  66
  67 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
  68 {
  69         struct cpuid_command cmd;
  70
  71         preempt_disable();
  72         if (cpu == smp_processor_id()) {
  73                 cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  74         } else {
  75                 cmd.cpu = cpu;
  76                 cmd.reg = reg;
  77                 cmd.data = data;
  78
  79                 smp_call_function(cpuid_smp_cpuid, &cmd, 1, 1);
  80         }
  81         preempt_enable();
  82 }
  83 #else                           /* ! CONFIG_SMP */
  84
  85 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
  86 {
  87         cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  88 }
  89
  90 #endif                          /* ! CONFIG_SMP */
  91
  92 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
  93 {
  94         loff_t ret;
  95
  96         lock_kernel();
  97
  98         switch (orig) {
  99         case 0:
 100                 file->f_pos = offset;
 101                 ret = file->f_pos;
 102                 break;
 103         case 1:
 104                 file->f_pos += offset;
 105                 ret = file->f_pos;
 106                 break;
 107         default:
 108                 ret = -EINVAL;
 109         }
 110
 111         unlock_kernel();
 112         return ret;
 113 }
 114
 115 static ssize_t cpuid_read(struct file *file, char __user *buf,
 116                           size_t count, loff_t * ppos)
 117 {
 118         char __user *tmp = buf;
 119         u32 data[4];
 120         size_t rv;
 121         u32 reg = *ppos;
 122         int cpu = iminor(file->f_dentry->d_inode);
 123
 124         if (count % 16)
 125                 return -EINVAL; /* Invalid chunk size */
 126
 127         for (rv = 0; count; count -= 16) {
 128                 do_cpuid(cpu, reg, data);
 129                 if (copy_to_user(tmp, &data, 16))
 130                         return -EFAULT;
 131                 tmp += 16;
 132                 *ppos = reg++;
 133         }
 134
 135         return tmp - buf;
 136 }
 137
 138 static int cpuid_open(struct inode *inode, struct file *file)
 139 {
 140         unsigned int cpu = iminor(file->f_dentry->d_inode);
 141         struct cpuinfo_x86 *c = &(cpu_data)[cpu];
 142
 143         if (cpu >= NR_CPUS || !cpu_online(cpu))
 144                 return -ENXIO;  /* No such CPU */
 145         if (c->cpuid_level < 0)
 146                 return -EIO;    /* CPUID not supported */
 147
 148         return 0;
 149 }
 150
 151 /*
 152  * File operations we support
 153  */
 154 static struct file_operations cpuid_fops = {
 155         .owner = THIS_MODULE,
 156         .llseek = cpuid_seek,
 157         .read = cpuid_read,
 158         .open = cpuid_open,
 159 };
 160
 161 static int cpuid_class_simple_device_add(int i)
 162 {
 163         int err = 0;
 164         struct class_device *class_err;
 165
 166         class_err = class_simple_device_add(cpuid_class, MKDEV(CPUID_MAJOR, i), NULL, "cpu%d",i);
 167         if (IS_ERR(class_err))
 168                 err = PTR_ERR(class_err);
 169         return err;
 170 }
 171
 172 static int __devinit cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 173 {
 174         unsigned int cpu = (unsigned long)hcpu;
 175
 176         switch (action) {
 177         case CPU_ONLINE:
 178                 cpuid_class_simple_device_add(cpu);
 179                 break;
 180         case CPU_DEAD:
 181                 class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));
 182                 break;
 183         }
 184         return NOTIFY_OK;
 185 }
 186
 187 static struct notifier_block cpuid_class_cpu_notifier =
 188 {
 189         .notifier_call = cpuid_class_cpu_callback,
 190 };
 191
 192 static int __init cpuid_init(void)
 193 {
 194         int i, err = 0;
 195         i = 0;
 196
 197         if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) {
 198                 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
 199                        CPUID_MAJOR);
 200                 err = -EBUSY;
 201                 goto out;
 202         }
 203         cpuid_class = class_simple_create(THIS_MODULE, "cpuid");
 204         if (IS_ERR(cpuid_class)) {
 205                 err = PTR_ERR(cpuid_class);
 206                 goto out_chrdev;
 207         }
 208         for_each_online_cpu(i) {
 209                 err = cpuid_class_simple_device_add(i);
 210                 if (err != 0)
 211                         goto out_class;
 212         }
 213         register_cpu_notifier(&cpuid_class_cpu_notifier);
 214
 215         err = 0;
 216         goto out;
 217
 218 out_class:
 219         i = 0;
 220         for_each_online_cpu(i) {
 221                 class_simple_device_remove(MKDEV(CPUID_MAJOR, i));
 222         }
 223         class_simple_destroy(cpuid_class);
 224 out_chrdev:
 225         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 226 out:
 227         return err;
 228 }
 229
 230 static void __exit cpuid_exit(void)
 231 {
 232         int cpu = 0;
 233
 234         for_each_online_cpu(cpu)
 235                 class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));
 236         class_simple_destroy(cpuid_class);
 237         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 238         unregister_cpu_notifier(&cpuid_class_cpu_notifier);
 239 }
 240
 241 module_init(cpuid_init);
 242 module_exit(cpuid_exit);
 243
 244 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 245 MODULE_DESCRIPTION("x86 generic CPUID driver");
 246 MODULE_LICENSE("GPL");