Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/* ----------------------------------------------------------------------- *

 *

 *   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.

 *

 * ----------------------------------------------------------------------- */

/*

 * 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/types.h>

#include <linux/errno.h>

#include <linux/fcntl.h>

#include <linux/init.h>

#include <linux/poll.h>

#include <linux/smp.h>

#include <linux/smp_lock.h>

#include <linux/major.h>

#include <linux/fs.h>

#include <linux/device.h>

#include <linux/cpu.h>

#include <linux/notifier.h>

#include <asm/processor.h>

#include <asm/msr.h>

#include <asm/uaccess.h>

#include <asm/system.h>

static struct class *msr_class;

static loff_t msr_seek(struct file *file, loff_t offset, int orig)

{

        loff_t ret = -EINVAL;

        lock_kernel();

        switch (orig) {

        case 0:

                file->f_pos = offset;

                ret = file->f_pos;

                break;

        case 1:

                file->f_pos += offset;

                ret = file->f_pos;

        }

        unlock_kernel();

        return ret;

}

static ssize_t msr_read(struct file *file, char __user * buf,

                        size_t count, loff_t * ppos)

{

        u32 __user *tmp = (u32 __user *) buf;

        u32 data[2];

        u32 reg = *ppos;

        int cpu = iminor(file->f_path.dentry->d_inode);

        int err;

        if (count % 8)

                return -EINVAL; /* Invalid chunk size */

        for (; count; count -= 8) {

                err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);

                if (err)

                        return -EIO;

                if (copy_to_user(tmp, &data, 8))

                        return -EFAULT;

                tmp += 2;

        }

        return ((char __user *)tmp) - buf;

}

static ssize_t msr_write(struct file *file, const char __user *buf,

                         size_t count, loff_t *ppos)

{

        const u32 __user *tmp = (const u32 __user *)buf;

        u32 data[2];

        u32 reg = *ppos;

        int cpu = iminor(file->f_path.dentry->d_inode);

        int err;

        if (count % 8)

                return -EINVAL; /* Invalid chunk size */

        for (; count; count -= 8) {

                if (copy_from_user(&data, tmp, 8))

                        return -EFAULT;

                err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);

                if (err)

                        return -EIO;

                tmp += 2;

        }

        return ((char __user *)tmp) - buf;

}

static int msr_open(struct inode *inode, struct file *file)

{

        unsigned int cpu = iminor(file->f_path.dentry->d_inode);

        struct cpuinfo_x86 *c = &cpu_data(cpu);

        if (cpu >= NR_CPUS || !cpu_online(cpu))

                return -ENXIO;  /* No such CPU */

        if (!cpu_has(c, X86_FEATURE_MSR))

                return -EIO;    /* MSR not supported */

        return 0;

}

/*

 * File operations we support

 */

static const struct file_operations msr_fops = {

        .owner = THIS_MODULE,

        .llseek = msr_seek,

        .read = msr_read,

        .write = msr_write,

        .open = msr_open,

};

static int __cpuinit msr_device_create(int cpu)

{

        struct device *dev;

        dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),

                            "msr%d", cpu);

        return IS_ERR(dev) ? PTR_ERR(dev) : 0;

}

static void msr_device_destroy(int cpu)

{

        device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));

}

static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,

                                unsigned long action, void *hcpu)

{

        unsigned int cpu = (unsigned long)hcpu;

        int err = 0;

        switch (action) {

        case CPU_UP_PREPARE:

        case CPU_UP_PREPARE_FROZEN:

                err = msr_device_create(cpu);

                break;

        case CPU_UP_CANCELED:

        case CPU_UP_CANCELED_FROZEN:

        case CPU_DEAD:

        case CPU_DEAD_FROZEN:

                msr_device_destroy(cpu);

                break;

        }

        return err ? NOTIFY_BAD : NOTIFY_OK;

}

static struct notifier_block __cpuinitdata msr_class_cpu_notifier = {

        .notifier_call = msr_class_cpu_callback,

};

static int __init msr_init(void)

{

        int i, err = 0;

        i = 0;

        if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {

                printk(KERN_ERR "msr: unable to get major %d for msr\n",

                       MSR_MAJOR);

                err = -EBUSY;

                goto out;

        }

        msr_class = class_create(THIS_MODULE, "msr");

        if (IS_ERR(msr_class)) {

                err = PTR_ERR(msr_class);

                goto out_chrdev;

        }

        for_each_online_cpu(i) {

                err = msr_device_create(i);

                if (err != 0)

                        goto out_class;

        }

        register_hotcpu_notifier(&msr_class_cpu_notifier);

        err = 0;

        goto out;

out_class:

        i = 0;

        for_each_online_cpu(i)

                msr_device_destroy(i);

        class_destroy(msr_class);

out_chrdev:

        unregister_chrdev(MSR_MAJOR, "cpu/msr");

out:

        return err;

}

static void __exit msr_exit(void)

{

        int cpu = 0;

        for_each_online_cpu(cpu)

                msr_device_destroy(cpu);

        class_destroy(msr_class);

        unregister_chrdev(MSR_MAJOR, "cpu/msr");

        unregister_hotcpu_notifier(&msr_class_cpu_notifier);

}

module_init(msr_init);

module_exit(msr_exit)

MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");

MODULE_DESCRIPTION("x86 generic MSR driver");

MODULE_LICENSE("GPL");