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 #ifdef CONFIG_SMP 47 48 struct cpuid_command { 49 u32 reg; 50 u32 *data; 51 }; 52 53 static void cpuid_smp_cpuid(void *cmd_block) 54 { 55 struct cpuid_command *cmd = (struct cpuid_command *)cmd_block; 56 57 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2], 58 &cmd->data[3]); 59 } 60 61 static inline void do_cpuid(int cpu, u32 reg, u32 * data) 62 { 63 struct cpuid_command cmd; 64 65 preempt_disable(); 66 if (cpu == smp_processor_id()) { 67 cpuid(reg, &data[0], &data[1], &data[2], &data[3]); 68 } else { 69 cmd.reg = reg; 70 cmd.data = data; 71 72 smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1); 73 } 74 preempt_enable(); 75 } 76 #else /* ! CONFIG_SMP */ 77 78 static inline void do_cpuid(int cpu, u32 reg, u32 * data) 79 { 80 cpuid(reg, &data[0], &data[1], &data[2], &data[3]); 81 } 82 83 #endif /* ! CONFIG_SMP */ 84 85 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig) 86 { 87 loff_t ret; 88 89 lock_kernel(); 90 91 switch (orig) { 92 case 0: 93 file->f_pos = offset; 94 ret = file->f_pos; 95 break; 96 case 1: 97 file->f_pos += offset; 98 ret = file->f_pos; 99 break; 100 default: 101 ret = -EINVAL; 102 } 103 104 unlock_kernel(); 105 return ret; 106 } 107 108 static ssize_t cpuid_read(struct file *file, char __user *buf, 109 size_t count, loff_t * ppos) 110 { 111 char __user *tmp = buf; 112 u32 data[4]; 113 u32 reg = *ppos; 114 int cpu = iminor(file->f_path.dentry->d_inode); 115 116 if (count % 16) 117 return -EINVAL; /* Invalid chunk size */ 118 119 for (; count; count -= 16) { 120 do_cpuid(cpu, reg, data); 121 if (copy_to_user(tmp, &data, 16)) 122 return -EFAULT; 123 tmp += 16; 124 *ppos = reg++; 125 } 126 127 return tmp - buf; 128 } 129 130 static int cpuid_open(struct inode *inode, struct file *file) 131 { 132 unsigned int cpu = iminor(file->f_path.dentry->d_inode); 133 struct cpuinfo_x86 *c = &(cpu_data)[cpu]; 134 135 if (cpu >= NR_CPUS || !cpu_online(cpu)) 136 return -ENXIO; /* No such CPU */ 137 if (c->cpuid_level < 0) 138 return -EIO; /* CPUID not supported */ 139 140 return 0; 141 } 142 143 /* 144 * File operations we support 145 */ 146 static const struct file_operations cpuid_fops = { 147 .owner = THIS_MODULE, 148 .llseek = cpuid_seek, 149 .read = cpuid_read, 150 .open = cpuid_open, 151 }; 152 153 static int cpuid_device_create(int i) 154 { 155 int err = 0; 156 struct device *dev; 157 158 dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i); 159 if (IS_ERR(dev)) 160 err = PTR_ERR(dev); 161 return err; 162 } 163 164 static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 165 { 166 unsigned int cpu = (unsigned long)hcpu; 167 168 switch (action) { 169 case CPU_ONLINE: 170 case CPU_ONLINE_FROZEN: 171 cpuid_device_create(cpu); 172 break; 173 case CPU_DEAD: 174 case CPU_DEAD_FROZEN: 175 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); 176 break; 177 } 178 return NOTIFY_OK; 179 } 180 181 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier = 182 { 183 .notifier_call = cpuid_class_cpu_callback, 184 }; 185 186 static int __init cpuid_init(void) 187 { 188 int i, err = 0; 189 i = 0; 190 191 if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) { 192 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", 193 CPUID_MAJOR); 194 err = -EBUSY; 195 goto out; 196 } 197 cpuid_class = class_create(THIS_MODULE, "cpuid"); 198 if (IS_ERR(cpuid_class)) { 199 err = PTR_ERR(cpuid_class); 200 goto out_chrdev; 201 } 202 for_each_online_cpu(i) { 203 err = cpuid_device_create(i); 204 if (err != 0) 205 goto out_class; 206 } 207 register_hotcpu_notifier(&cpuid_class_cpu_notifier); 208 209 err = 0; 210 goto out; 211 212 out_class: 213 i = 0; 214 for_each_online_cpu(i) { 215 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i)); 216 } 217 class_destroy(cpuid_class); 218 out_chrdev: 219 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); 220 out: 221 return err; 222 } 223 224 static void __exit cpuid_exit(void) 225 { 226 int cpu = 0; 227 228 for_each_online_cpu(cpu) 229 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); 230 class_destroy(cpuid_class); 231 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); 232 unregister_hotcpu_notifier(&cpuid_class_cpu_notifier); 233 } 234 235 module_init(cpuid_init); 236 module_exit(cpuid_exit); 237 238 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); 239 MODULE_DESCRIPTION("x86 generic CPUID driver"); 240 MODULE_LICENSE("GPL"); 241