diff options
Diffstat (limited to 'arch/x86/kernel/cpuid.c')
| -rw-r--r-- | arch/x86/kernel/cpuid.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c new file mode 100644 index 000000000..1d300f96d --- /dev/null +++ b/arch/x86/kernel/cpuid.c @@ -0,0 +1,196 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139, + * USA; either version 2 of the License, or (at your option) any later + * version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * x86 CPUID access device + * + * This device is accessed by lseek() to the appropriate CPUID level + * and then read in chunks of 16 bytes. A larger size means multiple + * reads of consecutive levels. + * + * The lower 32 bits of the file position is used as the incoming %eax, + * and the upper 32 bits of the file position as the incoming %ecx, + * the latter intended for "counting" eax levels like eax=4. + * + * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on + * an SMP box will direct the access to CPU %d. + */ + +#include <linux/module.h> + +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/fcntl.h> +#include <linux/init.h> +#include <linux/poll.h> +#include <linux/smp.h> +#include <linux/major.h> +#include <linux/fs.h> +#include <linux/device.h> +#include <linux/cpu.h> +#include <linux/notifier.h> +#include <linux/uaccess.h> +#include <linux/gfp.h> +#include <linux/completion.h> + +#include <asm/processor.h> +#include <asm/msr.h> + +static struct class *cpuid_class; +static enum cpuhp_state cpuhp_cpuid_state; + +struct cpuid_regs_done { + struct cpuid_regs regs; + struct completion done; +}; + +static void cpuid_smp_cpuid(void *cmd_block) +{ + struct cpuid_regs_done *cmd = cmd_block; + + cpuid_count(cmd->regs.eax, cmd->regs.ecx, + &cmd->regs.eax, &cmd->regs.ebx, + &cmd->regs.ecx, &cmd->regs.edx); + + complete(&cmd->done); +} + +static ssize_t cpuid_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + char __user *tmp = buf; + struct cpuid_regs_done cmd; + int cpu = iminor(file_inode(file)); + u64 pos = *ppos; + ssize_t bytes = 0; + int err = 0; + + if (count % 16) + return -EINVAL; /* Invalid chunk size */ + + init_completion(&cmd.done); + for (; count; count -= 16) { + call_single_data_t csd = { + .func = cpuid_smp_cpuid, + .info = &cmd, + }; + + cmd.regs.eax = pos; + cmd.regs.ecx = pos >> 32; + + err = smp_call_function_single_async(cpu, &csd); + if (err) + break; + wait_for_completion(&cmd.done); + if (copy_to_user(tmp, &cmd.regs, 16)) { + err = -EFAULT; + break; + } + tmp += 16; + bytes += 16; + *ppos = ++pos; + reinit_completion(&cmd.done); + } + + return bytes ? bytes : err; +} + +static int cpuid_open(struct inode *inode, struct file *file) +{ + unsigned int cpu; + struct cpuinfo_x86 *c; + + cpu = iminor(file_inode(file)); + if (cpu >= nr_cpu_ids || !cpu_online(cpu)) + return -ENXIO; /* No such CPU */ + + c = &cpu_data(cpu); + if (c->cpuid_level < 0) + return -EIO; /* CPUID not supported */ + + return 0; +} + +/* + * File operations we support + */ +static const struct file_operations cpuid_fops = { + .owner = THIS_MODULE, + .llseek = no_seek_end_llseek, + .read = cpuid_read, + .open = cpuid_open, +}; + +static int cpuid_device_create(unsigned int cpu) +{ + struct device *dev; + + dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL, + "cpu%d", cpu); + return PTR_ERR_OR_ZERO(dev); +} + +static int cpuid_device_destroy(unsigned int cpu) +{ + device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu)); + return 0; +} + +static char *cpuid_devnode(struct device *dev, umode_t *mode) +{ + return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt)); +} + +static int __init cpuid_init(void) +{ + int err; + + if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS, + "cpu/cpuid", &cpuid_fops)) { + printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n", + CPUID_MAJOR); + return -EBUSY; + } + cpuid_class = class_create(THIS_MODULE, "cpuid"); + if (IS_ERR(cpuid_class)) { + err = PTR_ERR(cpuid_class); + goto out_chrdev; + } + cpuid_class->devnode = cpuid_devnode; + + err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online", + cpuid_device_create, cpuid_device_destroy); + if (err < 0) + goto out_class; + + cpuhp_cpuid_state = err; + return 0; + +out_class: + class_destroy(cpuid_class); +out_chrdev: + __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); + return err; +} +module_init(cpuid_init); + +static void __exit cpuid_exit(void) +{ + cpuhp_remove_state(cpuhp_cpuid_state); + class_destroy(cpuid_class); + __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid"); +} +module_exit(cpuid_exit); + +MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); +MODULE_DESCRIPTION("x86 generic CPUID driver"); +MODULE_LICENSE("GPL"); |