LXR linux/arch/um/drivers/mmapper

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * arch/um/drivers/mmapper_kern.c
   4 *
   5 * BRIEF MODULE DESCRIPTION
   6 *
   7 * Copyright (C) 2000 RidgeRun, Inc.
   8 * Author: RidgeRun, Inc.
   9 *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
  10 *
  11 */
  12
  13#include <linux/stddef.h>
  14#include <linux/types.h>
  15#include <linux/fs.h>
  16#include <linux/init.h>
  17#include <linux/miscdevice.h>
  18#include <linux/module.h>
  19#include <linux/mm.h>
  20
  21#include <linux/uaccess.h>
  22#include <mem_user.h>
  23
  24/* These are set in mmapper_init, which is called at boot time */
  25static unsigned long mmapper_size;
  26static unsigned long p_buf;
  27static char *v_buf;
  28
  29static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
  30                            loff_t *ppos)
  31{
  32        return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
  33}
  34
  35static ssize_t mmapper_write(struct file *file, const char __user *buf,
  36                             size_t count, loff_t *ppos)
  37{
  38        if (*ppos > mmapper_size)
  39                return -EINVAL;
  40
  41        return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
  42}
  43
  44static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  45{
  46        return -ENOIOCTLCMD;
  47}
  48
  49static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
  50{
  51        int ret = -EINVAL;
  52        int size;
  53
  54        if (vma->vm_pgoff != 0)
  55                goto out;
  56
  57        size = vma->vm_end - vma->vm_start;
  58        if (size > mmapper_size)
  59                return -EFAULT;
  60
  61        /*
  62         * XXX A comment above remap_pfn_range says it should only be
  63         * called when the mm semaphore is held
  64         */
  65        if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
  66                            vma->vm_page_prot))
  67                goto out;
  68        ret = 0;
  69out:
  70        return ret;
  71}
  72
  73static int mmapper_open(struct inode *inode, struct file *file)
  74{
  75        return 0;
  76}
  77
  78static int mmapper_release(struct inode *inode, struct file *file)
  79{
  80        return 0;
  81}
  82
  83static const struct file_operations mmapper_fops = {
  84        .owner          = THIS_MODULE,
  85        .read           = mmapper_read,
  86        .write          = mmapper_write,
  87        .unlocked_ioctl = mmapper_ioctl,
  88        .mmap           = mmapper_mmap,
  89        .open           = mmapper_open,
  90        .release        = mmapper_release,
  91        .llseek         = default_llseek,
  92};
  93
  94/*
  95 * No locking needed - only used (and modified) by below initcall and exitcall.
  96 */
  97static struct miscdevice mmapper_dev = {
  98        .minor          = MISC_DYNAMIC_MINOR,
  99        .name           = "mmapper",
 100        .fops           = &mmapper_fops
 101};
 102
 103static int __init mmapper_init(void)
 104{
 105        int err;
 106
 107        printk(KERN_INFO "Mapper v0.1\n");
 108
 109        v_buf = (char *) find_iomem("mmapper", &mmapper_size);
 110        if (mmapper_size == 0) {
 111                printk(KERN_ERR "mmapper_init - find_iomem failed\n");
 112                return -ENODEV;
 113        }
 114        p_buf = __pa(v_buf);
 115
 116        err = misc_register(&mmapper_dev);
 117        if (err) {
 118                printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
 119                       err);
 120                return err;
 121        }
 122        return 0;
 123}
 124
 125static void mmapper_exit(void)
 126{
 127        misc_deregister(&mmapper_dev);
 128}
 129
 130module_init(mmapper_init);
 131module_exit(mmapper_exit);
 132
 133MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
 134MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
 135MODULE_LICENSE("GPL");
 136