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mmapper_kern.c

/*
 * arch/um/drivers/mmapper_kern.c
 *
 * BRIEF MODULE DESCRIPTION
 *
 * Copyright (C) 2000 RidgeRun, Inc.
 * Author: RidgeRun, Inc.
 *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
 *
 */

#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 <linux/smp_lock.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;

      if (count > mmapper_size - *ppos)
            count = mmapper_size - *ppos;

      if (copy_from_user(&v_buf[*ppos], buf, count))
            return -EFAULT;

      return count;
}

static int mmapper_ioctl(struct inode *inode, 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)
{
      cycle_kernel_lock();
      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,
      .ioctl            = mmapper_ioctl,
      .mmap       = mmapper_mmap,
      .open       = mmapper_open,
      .release    = mmapper_release,
};

/*
 * 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");
            goto out;
      }

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

      p_buf = __pa(v_buf);
out:
      return 0;
}

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

module_init(mmapper_init);
module_exit(mmapper_exit);

MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");

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