1/*
2 * linux/drivers/video/fb_sys_read.c - Generic file operations where
3 * framebuffer is in system RAM
4 *
5 * Copyright (C) 2007 Antonino Daplas <adaplas@pol.net>
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License.  See the file COPYING in the main directory of this archive
9 * for more details.
10 *
11 */
12#include <linux/fb.h>
13#include <linux/module.h>
14#include <asm/uaccess.h>
15
16ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count,
17		    loff_t *ppos)
18{
19	unsigned long p = *ppos;
20	void *src;
21	int err = 0;
22	unsigned long total_size;
23
24	if (info->state != FBINFO_STATE_RUNNING)
25		return -EPERM;
26
27	total_size = info->screen_size;
28
29	if (total_size == 0)
30		total_size = info->fix.smem_len;
31
32	if (p >= total_size)
33		return 0;
34
35	if (count >= total_size)
36		count = total_size;
37
38	if (count + p > total_size)
39		count = total_size - p;
40
41	src = (void __force *)(info->screen_base + p);
42
43	if (info->fbops->fb_sync)
44		info->fbops->fb_sync(info);
45
46	if (copy_to_user(buf, src, count))
47		err = -EFAULT;
48
49	if  (!err)
50		*ppos += count;
51
52	return (err) ? err : count;
53}
54EXPORT_SYMBOL_GPL(fb_sys_read);
55
56ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
57		     size_t count, loff_t *ppos)
58{
59	unsigned long p = *ppos;
60	void *dst;
61	int err = 0;
62	unsigned long total_size;
63
64	if (info->state != FBINFO_STATE_RUNNING)
65		return -EPERM;
66
67	total_size = info->screen_size;
68
69	if (total_size == 0)
70		total_size = info->fix.smem_len;
71
72	if (p > total_size)
73		return -EFBIG;
74
75	if (count > total_size) {
76		err = -EFBIG;
77		count = total_size;
78	}
79
80	if (count + p > total_size) {
81		if (!err)
82			err = -ENOSPC;
83
84		count = total_size - p;
85	}
86
87	dst = (void __force *) (info->screen_base + p);
88
89	if (info->fbops->fb_sync)
90		info->fbops->fb_sync(info);
91
92	if (copy_from_user(dst, buf, count))
93		err = -EFAULT;
94
95	if  (!err)
96		*ppos += count;
97
98	return (err) ? err : count;
99}
100EXPORT_SYMBOL_GPL(fb_sys_write);
101
102MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
103MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
104MODULE_LICENSE("GPL");
105