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
  28 #include <linux/types.h>
  29 #include <linux/errno.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/init.h>
  32 #include <linux/poll.h>
  33 #include <linux/smp.h>
  34 #include <linux/major.h>
  35 #include <linux/fs.h>
  36 #include <linux/smp_lock.h>
  37 #include <linux/fs.h>
  38 #include <linux/device.h>
  39 #include <linux/cpu.h>
  40 #include <linux/notifier.h>
  41
  42 #include <asm/processor.h>
  43 #include <asm/msr.h>
  44 #include <asm/uaccess.h>
  45 #include <asm/system.h>
  46
  47 static struct class *cpuid_class;
  48
  49 #ifdef CONFIG_SMP
  50
  51 struct cpuid_command {
  52         int cpu;
  53         u32 reg;
  54         u32 *data;
  55 };
  56
  57 static void cpuid_smp_cpuid(void *cmd_block)
  58 {
  59         struct cpuid_command *cmd = (struct cpuid_command *)cmd_block;
  60
  61         if (cmd->cpu == smp_processor_id())
  62                 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2],
  63                       &cmd->data[3]);
  64 }
  65
  66 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
  67 {
  68         struct cpuid_command cmd;
  69
  70         preempt_disable();
  71         if (cpu == smp_processor_id()) {
  72                 cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  73         } else {
  74                 cmd.cpu = cpu;
  75                 cmd.reg = reg;
  76                 cmd.data = data;
  77
  78                 smp_call_function(cpuid_smp_cpuid, &cmd, 1, 1);
  79         }
  80         preempt_enable();
  81 }
  82 #else                           /* ! CONFIG_SMP */
  83
  84 static inline void do_cpuid(int cpu, u32 reg, u32 * data)
  85 {
  86         cpuid(reg, &data[0], &data[1], &data[2], &data[3]);
  87 }
  88
  89 #endif                          /* ! CONFIG_SMP */
  90
  91 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
  92 {
  93         loff_t ret;
  94
  95         lock_kernel();
  96
  97         switch (orig) {
  98         case 0:
  99                 file->f_pos = offset;
 100                 ret = file->f_pos;
 101                 break;
 102         case 1:
 103                 file->f_pos += offset;
 104                 ret = file->f_pos;
 105                 break;
 106         default:
 107                 ret = -EINVAL;
 108         }
 109
 110         unlock_kernel();
 111         return ret;
 112 }
 113
 114 static ssize_t cpuid_read(struct file *file, char __user *buf,
 115                           size_t count, loff_t * ppos)
 116 {
 117         char __user *tmp = buf;
 118         u32 data[4];
 119         u32 reg = *ppos;
 120         int cpu = iminor(file->f_dentry->d_inode);
 121
 122         if (count % 16)
 123                 return -EINVAL; /* Invalid chunk size */
 124
 125         for (; count; count -= 16) {
 126                 do_cpuid(cpu, reg, data);
 127                 if (copy_to_user(tmp, &data, 16))
 128                         return -EFAULT;
 129                 tmp += 16;
 130                 *ppos = reg++;
 131         }
 132
 133         return tmp - buf;
 134 }
 135
 136 static int cpuid_open(struct inode *inode, struct file *file)
 137 {
 138         unsigned int cpu = iminor(file->f_dentry->d_inode);
 139         struct cpuinfo_x86 *c = &(cpu_data)[cpu];
 140
 141         if (cpu >= NR_CPUS || !cpu_online(cpu))
 142                 return -ENXIO;  /* No such CPU */
 143         if (c->cpuid_level < 0)
 144                 return -EIO;    /* CPUID not supported */
 145
 146         return 0;
 147 }
 148
 149 /*
 150  * File operations we support
 151  */
 152 static struct file_operations cpuid_fops = {
 153         .owner = THIS_MODULE,
 154         .llseek = cpuid_seek,
 155         .read = cpuid_read,
 156         .open = cpuid_open,
 157 };
 158
 159 static int cpuid_device_create(int i)
 160 {
 161         int err = 0;
 162         struct device *dev;
 163
 164         dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i);
 165         if (IS_ERR(dev))
 166                 err = PTR_ERR(dev);
 167         return err;
 168 }
 169
 170 #ifdef CONFIG_HOTPLUG_CPU
 171 static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 172 {
 173         unsigned int cpu = (unsigned long)hcpu;
 174
 175         switch (action) {
 176         case CPU_ONLINE:
 177                 cpuid_device_create(cpu);
 178                 break;
 179         case CPU_DEAD:
 180                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 181                 break;
 182         }
 183         return NOTIFY_OK;
 184 }
 185
 186 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
 187 {
 188         .notifier_call = cpuid_class_cpu_callback,
 189 };
 190 #endif /* !CONFIG_HOTPLUG_CPU */
 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_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_device_create(i);
 210                 if (err != 0)
 211                         goto out_class;
 212         }
 213         register_hotcpu_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                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i));
 222         }
 223         class_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                 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 236         class_destroy(cpuid_class);
 237         unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 238         unregister_hotcpu_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");