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 __exit 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