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"); 233