linux/arch/um/drivers/mmapper_kern.c
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   1/*
   2 * arch/um/drivers/mmapper_kern.c
   3 *
   4 * BRIEF MODULE DESCRIPTION
   5 *
   6 * Copyright (C) 2000 RidgeRun, Inc.
   7 * Author: RidgeRun, Inc.
   8 *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
   9 *
  10 */
  11
  12#include <linux/stddef.h>
  13#include <linux/types.h>
  14#include <linux/fs.h>
  15#include <linux/init.h>
  16#include <linux/miscdevice.h>
  17#include <linux/module.h>
  18#include <linux/mm.h>
  19
  20#include <asm/uaccess.h>
  21#include "mem_user.h"
  22
  23/* These are set in mmapper_init, which is called at boot time */
  24static unsigned long mmapper_size;
  25static unsigned long p_buf;
  26static char *v_buf;
  27
  28static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
  29                            loff_t *ppos)
  30{
  31        return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
  32}
  33
  34static ssize_t mmapper_write(struct file *file, const char __user *buf,
  35                             size_t count, loff_t *ppos)
  36{
  37        if (*ppos > mmapper_size)
  38                return -EINVAL;
  39
  40        return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
  41}
  42
  43static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  44{
  45        return -ENOIOCTLCMD;
  46}
  47
  48static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
  49{
  50        int ret = -EINVAL;
  51        int size;
  52
  53        if (vma->vm_pgoff != 0)
  54                goto out;
  55
  56        size = vma->vm_end - vma->vm_start;
  57        if (size > mmapper_size)
  58                return -EFAULT;
  59
  60        /*
  61         * XXX A comment above remap_pfn_range says it should only be
  62         * called when the mm semaphore is held
  63         */
  64        if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
  65                            vma->vm_page_prot))
  66                goto out;
  67        ret = 0;
  68out:
  69        return ret;
  70}
  71
  72static int mmapper_open(struct inode *inode, struct file *file)
  73{
  74        return 0;
  75}
  76
  77static int mmapper_release(struct inode *inode, struct file *file)
  78{
  79        return 0;
  80}
  81
  82static const struct file_operations mmapper_fops = {
  83        .owner          = THIS_MODULE,
  84        .read           = mmapper_read,
  85        .write          = mmapper_write,
  86        .unlocked_ioctl = mmapper_ioctl,
  87        .mmap           = mmapper_mmap,
  88        .open           = mmapper_open,
  89        .release        = mmapper_release,
  90        .llseek         = default_llseek,
  91};
  92
  93/*
  94 * No locking needed - only used (and modified) by below initcall and exitcall.
  95 */
  96static struct miscdevice mmapper_dev = {
  97        .minor          = MISC_DYNAMIC_MINOR,
  98        .name           = "mmapper",
  99        .fops           = &mmapper_fops
 100};
 101
 102static int __init mmapper_init(void)
 103{
 104        int err;
 105
 106        printk(KERN_INFO "Mapper v0.1\n");
 107
 108        v_buf = (char *) find_iomem("mmapper", &mmapper_size);
 109        if (mmapper_size == 0) {
 110                printk(KERN_ERR "mmapper_init - find_iomem failed\n");
 111                return -ENODEV;
 112        }
 113        p_buf = __pa(v_buf);
 114
 115        err = misc_register(&mmapper_dev);
 116        if (err) {
 117                printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
 118                       err);
 119                return err;
 120        }
 121        return 0;
 122}
 123
 124static void mmapper_exit(void)
 125{
 126        misc_deregister(&mmapper_dev);
 127}
 128
 129module_init(mmapper_init);
 130module_exit(mmapper_exit);
 131
 132MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
 133MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
 134MODULE_LICENSE("GPL");
 135
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