diff options
Diffstat (limited to 'arch/i386/kernel/msr.c')
| -rw-r--r-- | arch/i386/kernel/msr.c | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/arch/i386/kernel/msr.c b/arch/i386/kernel/msr.c new file mode 100644 index 000000000..2ab1ecf33 --- /dev/null +++ b/arch/i386/kernel/msr.c @@ -0,0 +1,274 @@ +#ident "$Id$" +/* ----------------------------------------------------------------------- * + * + * Copyright 2000 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. + * + * ----------------------------------------------------------------------- */ + +/* + * msr.c + * + * x86 MSR access device + * + * This device is accessed by lseek() to the appropriate register number + * and then read/write in chunks of 8 bytes. A larger size means multiple + * reads or writes of the same register. + * + * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on + * an SMP box will direct the access to CPU %d. + */ + +#include <linux/module.h> +#include <linux/config.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 <asm/processor.h> +#include <asm/msr.h> +#include <asm/uaccess.h> +#include <asm/system.h> + +extern inline int wrmsr_eio(u32 reg, u32 eax, u32 edx) +{ + int err = 0; + + asm volatile( + "1: wrmsr\n" + "2:\n" + ".section .fixup,\"ax\"\n" + "3: movl %4,%0\n" + " jmp 1b\n" + ".previous\n" + ".section __ex_table,\"a\"\n" + " .align 4\n" + " .long 1b,3b\n" + ".previous" + : "+r" (err) + : "a" (eax), "d" (edx), "c" (reg), "i" (-EIO)); + + return err; +} + +extern inline int rdmsr_eio(u32 reg, u32 *eax, u32 *edx) +{ + int err = 0; + + asm volatile( + "1: rdmsr\n" + "2:\n" + ".section .fixup,\"ax\"\n" + "3: movl %4,%0\n" + " jmp 1b\n" + ".previous\n" + ".section __ex_table,\"a\"\n" + " .align 4\n" + " .long 1b,3b\n" + ".previous" + : "+r" (err), "=a" (*eax), "=d" (*eax) + : "c" (reg), "i" (-EIO)); + + return err; +} + +#ifdef CONFIG_SMP + +struct msr_command { + int cpu; + int err; + u32 reg; + u32 data[2]; +}; + +static void msr_smp_wrmsr(void *cmd_block) +{ + struct msr_command *cmd = (struct msr_command *) cmd_block; + + if ( cmd->cpu == smp_processor_id() ) + cmd->err = wrmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]); +} + +static void msr_smp_rdmsr(void *cmd_block) +{ + struct msr_command *cmd = (struct msr_command *) cmd_block; + + if ( cmd->cpu == smp_processor_id() ) + cmd->err = rdmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]); +} + +extern inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx) +{ + struct msr_command cmd; + + if ( cpu == smp_processor_id() ) { + return wrmsr_eio(reg, eax, edx); + } else { + cmd.cpu = cpu; + cmd.reg = reg; + cmd.data[0] = eax; + cmd.data[1] = edx; + + smp_call_function(msr_smp_wrmsr, (void *)cmd, 1, 1); + return cmd.err; + } +} + +extern inline int do_rdmsr(int cpu, u32 reg, u32 *eax, u32 *edx) +{ + struct msr_command cmd; + + if ( cpu == smp_processor_id() ) { + return rdmsr_eio(reg, eax, edx); + } else { + cmd.cpu = cpu; + cmd.reg = reg; + + smp_call_function(msr_smp_rdmsr, (void *)cmd, 1, 1); + + *eax = cmd.data[0]; + *edx = cmd.data[1]; + + return cmd.err; + } +} + +#else /* ! CONFIG_SMP */ + +extern inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx) +{ + return wrmsr_eio(reg, eax, edx); +} + +extern inline int do_rdmsr(int cpu, u32 reg, u32 *eax, u32 *edx) +{ + return rdmsr_eio(reg, eax, edx); +} + +#endif /* ! CONFIG_SMP */ + +static loff_t msr_seek(struct file *file, loff_t offset, int orig) +{ + switch (orig) { + case 0: + file->f_pos = offset; + return file->f_pos; + case 1: + file->f_pos += offset; + return file->f_pos; + default: + return -EINVAL; /* SEEK_END not supported */ + } +} + +static ssize_t msr_read(struct file * file, char * buf, + size_t count, loff_t *ppos) +{ + u32 *tmp = (u32 *)buf; + u32 data[2]; + size_t rv; + u32 reg = *ppos; + int cpu = MINOR(file->f_dentry->d_inode->i_rdev); + int err; + + if ( count % 8 ) + return -EINVAL; /* Invalid chunk size */ + + for ( rv = 0 ; count ; count -= 8 ) { + err = do_rdmsr(cpu, reg, &data[0], &data[1]); + if ( err ) + return err; + if ( copy_to_user(tmp,&data,8) ) + return -EFAULT; + tmp += 2; + } + + return ((char *)tmp) - buf; +} + +static ssize_t msr_write(struct file * file, const char * buf, + size_t count, loff_t *ppos) +{ + const u32 *tmp = (const u32 *)buf; + u32 data[2]; + size_t rv; + u32 reg = *ppos; + int cpu = MINOR(file->f_dentry->d_inode->i_rdev); + int err; + + if ( count % 8 ) + return -EINVAL; /* Invalid chunk size */ + + for ( rv = 0 ; count ; count -= 8 ) { + if ( copy_from_user(&data,tmp,8) ) + return -EFAULT; + err = do_wrmsr(cpu, reg, data[0], data[1]); + if ( err ) + return err; + tmp += 2; + } + + return ((char *)tmp) - buf; +} + +static int msr_open(struct inode *inode, struct file *file) +{ + int cpu = MINOR(file->f_dentry->d_inode->i_rdev); + + if ( !(cpu_online_map & (1UL << cpu)) || + !((cpu_data)[cpu].x86_capability & X86_FEATURE_MSR) ) + return -ENXIO; /* No such CPU */ + + MOD_INC_USE_COUNT; + return 0; +} + +static int msr_release(struct inode *inode, struct file *file) +{ + MOD_DEC_USE_COUNT; + return 0; +} + +/* + * File operations we support + */ +static struct file_operations msr_fops = { + llseek: msr_seek, + read: msr_read, + write: msr_write, + open: msr_open, + release: msr_release, +}; + +int __init msr_init(void) +{ + if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) { + printk(KERN_ERR "msr: unable to get major %d for msr\n", + MSR_MAJOR); + return -EBUSY; + } + + return 0; +} + +void __exit msr_exit(void) +{ +} + +module_init(msr_init); +module_exit(msr_exit) + +EXPORT_NO_SYMBOLS; + +MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); +MODULE_DESCRIPTION("x86 generic MSR driver"); |