mmapper_kern.c

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/*
 * arch/um/drivers/mmapper_kern.c
 *
 * BRIEF MODULE DESCRIPTION
 *
 * Copyright (C) 2000 RidgeRun, Inc.
 * Author: RidgeRun, Inc.
 *         Greg Lonnon [email protected] or [email protected]
 *
 */

#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mm.h>

#include <asm/uaccess.h>
#include <mem_user.h>

/* These are set in mmapper_init, which is called at boot time */
static unsigned long mmapper_size;
static unsigned long p_buf;
static char *v_buf;

static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
                loff_t *ppos)
{
    return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
}

static ssize_t mmapper_write(struct file *file, const char __user *buf,
                 size_t count, loff_t *ppos)
{
    if (*ppos > mmapper_size)
        return -EINVAL;

    return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
}

static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    return -ENOIOCTLCMD;
}

static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
{
    int ret = -EINVAL;
    int size;

    if (vma->vm_pgoff != 0)
        goto out;

    size = vma->vm_end - vma->vm_start;
    if (size > mmapper_size)
        return -EFAULT;

    /*
     * XXX A comment above remap_pfn_range says it should only be
     * called when the mm semaphore is held
     */
    if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
                vma->vm_page_prot))
        goto out;
    ret = 0;
out:
    return ret;
}

static int mmapper_open(struct inode *inode, struct file *file)
{
    return 0;
}

static int mmapper_release(struct inode *inode, struct file *file)
{
    return 0;
}

static const struct file_operations mmapper_fops = {
    .owner      = THIS_MODULE,
    .read       = mmapper_read,
    .write      = mmapper_write,
    .unlocked_ioctl = mmapper_ioctl,
    .mmap       = mmapper_mmap,
    .open       = mmapper_open,
    .release    = mmapper_release,
    .llseek     = default_llseek,
};

/*
 * No locking needed - only used (and modified) by below initcall and exitcall.
 */
static struct miscdevice mmapper_dev = {
    .minor      = MISC_DYNAMIC_MINOR,
    .name       = "mmapper",
    .fops       = &mmapper_fops
};

static int __init mmapper_init(void)
{
    int err;

    printk(KERN_INFO "Mapper v0.1\n");

    v_buf = (char *) find_iomem("mmapper", &mmapper_size);
    if (mmapper_size == 0) {
        printk(KERN_ERR "mmapper_init - find_iomem failed\n");
        return -ENODEV;
    }
    p_buf = __pa(v_buf);

    err = misc_register(&mmapper_dev);
    if (err) {
        printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
               err);
        return err;
    }
    return 0;
}

static void mmapper_exit(void)
{
    misc_deregister(&mmapper_dev);
}

module_init(mmapper_init);
module_exit(mmapper_exit);

MODULE_AUTHOR("Greg Lonnon <[email protected]>");
MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
MODULE_LICENSE("GPL");