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/device.h> 38 #include <linux/cpu.h> 39 #include <linux/notifier.h> 40 41 #include <asm/processor.h> 42 #include <asm/msr.h> 43 #include <asm/uaccess.h> 44 #include <asm/system.h> 45 46 static struct class *cpuid_class; 47 48 #ifdef CONFIG_SMP 49 50 struct cpuid_command { 51 u32 reg; 52 u32 *data; 53 }; 54 55 static void cpuid_smp_cpuid(void *cmd_block) 56 { 57 struct cpuid_command *cmd = (struct cpuid_command *)cmd_block; 58 59 cpuid(cmd->reg, &cmd->data[0], &cmd->data[1], &cmd->data[2], 60 &cmd->data[3]); 61 } 62 63 static inline void do_cpuid(int cpu, u32 reg, u32 * data) 64 { 65 struct cpuid_command cmd; 66 67 preempt_disable(); 68 if (cpu == smp_processor_id()) { 69 cpuid(reg, &data[0], &data[1], &data[2], &data[3]); 70 } else { 71 cmd.reg = reg; 72 cmd.data = data; 73 74 smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1, 1); 75 } 76 preempt_enable(); 77 } 78 #else /* ! CONFIG_SMP */ 79 80 static inline void do_cpuid(int cpu, u32 reg, u32 * data) 81 { 82 cpuid(reg, &data[0], &data[1], &data[2], &data[3]); 83 } 84 85 #endif /* ! CONFIG_SMP */ 86 87 static loff_t cpuid_seek(struct file *file, loff_t offset, int orig) 88 { 89 loff_t ret; 90 91 lock_kernel(); 92 93 switch (orig) { 94 case 0: 95 file->f_pos = offset; 96 ret = file->f_pos; 97 break; 98 case 1: 99 file->f_pos += offset; 100 ret = file->f_pos; 101 break; 102 default: 103 ret = -EINVAL; 104 } 105 106 unlock_kernel(); 107 return ret; 108 } 109 110 static ssize_t cpuid_read(struct file *file, char __user *buf, 111 size_t count, loff_t * ppos) 112 { 113 char __user *tmp = buf; 114 u32 data[4]; 115 u32 reg = *ppos; 116 int cpu = iminor(file->f_path.dentry->d_inode); 117 118 if (count % 16) 119 return -EINVAL; /* Invalid chunk size */ 120 121 for (; count; count -= 16) { 122 do_cpuid(cpu, reg, data); 123 if (copy_to_user(tmp, &data, 16)) 124 return -EFAULT; 125 tmp += 16; 126 *ppos = reg++; 127 } 128 129 return tmp - buf; 130 } 131 132 static int cpuid_open(struct inode *inode, struct file *file) 133 { 134 unsigned int cpu = iminor(file->f_path.dentry->d_inode); 135 struct cpuinfo_x86 *c = &(cpu_data)[cpu]; 136 137 if (cpu >= NR_CPUS || !cpu_online(cpu)) 138 return -ENXIO; /* No such CPU */ 139 if (c->cpuid_level < 0) 140 return -EIO; /* CPUID not supported */ 141 142 return 0; 143 } 144 145 /* 146 * File operations we support 147 */ 148 static const struct file_operations cpuid_fops = { 149 .owner = THIS_MODULE, 150 .llseek = cpuid_seek, 151 .read = cpuid_read, 152 .open = cpuid_open, 153 }; 154 155 static int cpuid_device_create(int i) 156 { 157 int err = 0; 158 struct device *dev; 159 160 dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i); 161 if (IS_ERR(dev)) 162 err = PTR_ERR(dev); 163 return err; 164 } 165 166 static int cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 167 { 168 unsigned int cpu = (unsigned long)hcpu; 169 170 switch (action) { 171 case CPU_ONLINE: 172 case CPU_ONLINE_FROZEN: 173 cpuid_device_create(cpu); 174 break; 175 case CPU_DEAD: 176 case CPU_DEAD_FROZEN: 177 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); 178 break; 179 } 180 return NOTIFY_OK; 181 } 182 183 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier = 184 { 185 .notifier_call = cpuid_class_cpu_callback, 186 }; 187 188 static int __init cpuid_init(void) 189 { 190 int i, err = 0; 191 i = 0; 192 193 if (register_chrdev(CPUID_MAJOR, "cpu/cpuid", &cpuid_fops)) { 194 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", 195 CPUID_MAJOR); 196 err = -EBUSY; 197 goto out; 198 } 199 cpuid_class = class_create(THIS_MODULE, "cpuid"); 200 if (IS_ERR(cpuid_class)) { 201 err = PTR_ERR(cpuid_class); 202 goto out_chrdev; 203 } 204 for_each_online_cpu(i) { 205 err = cpuid_device_create(i); 206 if (err != 0) 207 goto out_class; 208 } 209 register_hotcpu_notifier(&cpuid_class_cpu_notifier); 210 211 err = 0; 212 goto out; 213 214 out_class: 215 i = 0; 216 for_each_online_cpu(i) { 217 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i)); 218 } 219 class_destroy(cpuid_class); 220 out_chrdev: 221 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); 222 out: 223 return err; 224 } 225 226 static void __exit cpuid_exit(void) 227 { 228 int cpu = 0; 229 230 for_each_online_cpu(cpu) 231 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); 232 class_destroy(cpuid_class); 233 unregister_chrdev(CPUID_MAJOR, "cpu/cpuid"); 234 unregister_hotcpu_notifier(&cpuid_class_cpu_notifier); 235 } 236 237 module_init(cpuid_init); 238 module_exit(cpuid_exit); 239 240 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); 241 MODULE_DESCRIPTION("x86 generic CPUID driver"); 242 MODULE_LICENSE("GPL"); 243