Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 <linux/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, c;
23 ssize_t ret;
24
25 if (!info->screen_buffer)
26 return -ENODEV;
27
28 total_size = info->screen_size;
29
30 if (total_size == 0)
31 total_size = info->fix.smem_len;
32
33 if (p >= total_size)
34 return 0;
35
36 if (count >= total_size)
37 count = total_size;
38
39 if (count + p > total_size)
40 count = total_size - p;
41
42 src = info->screen_buffer + p;
43
44 if (info->fbops->fb_sync)
45 info->fbops->fb_sync(info);
46
47 c = copy_to_user(buf, src, count);
48 if (c)
49 err = -EFAULT;
50 ret = count - c;
51
52 *ppos += ret;
53
54 return ret ? ret : err;
55}
56EXPORT_SYMBOL_GPL(fb_sys_read);
57
58ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
59 size_t count, loff_t *ppos)
60{
61 unsigned long p = *ppos;
62 void *dst;
63 int err = 0;
64 unsigned long total_size, c;
65 size_t ret;
66
67 if (!info->screen_buffer)
68 return -ENODEV;
69
70 total_size = info->screen_size;
71
72 if (total_size == 0)
73 total_size = info->fix.smem_len;
74
75 if (p > total_size)
76 return -EFBIG;
77
78 if (count > total_size) {
79 err = -EFBIG;
80 count = total_size;
81 }
82
83 if (count + p > total_size) {
84 if (!err)
85 err = -ENOSPC;
86
87 count = total_size - p;
88 }
89
90 dst = info->screen_buffer + p;
91
92 if (info->fbops->fb_sync)
93 info->fbops->fb_sync(info);
94
95 c = copy_from_user(dst, buf, count);
96 if (c)
97 err = -EFAULT;
98 ret = count - c;
99
100 *ppos += ret;
101
102 return ret ? ret : err;
103}
104EXPORT_SYMBOL_GPL(fb_sys_write);
105
106MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
107MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
108MODULE_LICENSE("GPL");