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
13#include <linux/export.h>
14#include <linux/fb.h>
15#include <linux/module.h>
16#include <linux/uaccess.h>
17
18ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count,
19 loff_t *ppos)
20{
21 unsigned long p = *ppos;
22 void *src;
23 int err = 0;
24 unsigned long total_size, c;
25 ssize_t ret;
26
27 if (!(info->flags & FBINFO_VIRTFB))
28 fb_warn_once(info, "Framebuffer is not in virtual address space.");
29
30 if (!info->screen_buffer)
31 return -ENODEV;
32
33 total_size = info->screen_size;
34
35 if (total_size == 0)
36 total_size = info->fix.smem_len;
37
38 if (p >= total_size)
39 return 0;
40
41 if (count >= total_size)
42 count = total_size;
43
44 if (count + p > total_size)
45 count = total_size - p;
46
47 src = info->screen_buffer + p;
48
49 if (info->fbops->fb_sync)
50 info->fbops->fb_sync(info);
51
52 c = copy_to_user(buf, src, count);
53 if (c)
54 err = -EFAULT;
55 ret = count - c;
56
57 *ppos += ret;
58
59 return ret ? ret : err;
60}
61EXPORT_SYMBOL_GPL(fb_sys_read);
62
63ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
64 size_t count, loff_t *ppos)
65{
66 unsigned long p = *ppos;
67 void *dst;
68 int err = 0;
69 unsigned long total_size, c;
70 size_t ret;
71
72 if (!(info->flags & FBINFO_VIRTFB))
73 fb_warn_once(info, "Framebuffer is not in virtual address space.");
74
75 if (!info->screen_buffer)
76 return -ENODEV;
77
78 total_size = info->screen_size;
79
80 if (total_size == 0)
81 total_size = info->fix.smem_len;
82
83 if (p > total_size)
84 return -EFBIG;
85
86 if (count > total_size) {
87 err = -EFBIG;
88 count = total_size;
89 }
90
91 if (count + p > total_size) {
92 if (!err)
93 err = -ENOSPC;
94
95 count = total_size - p;
96 }
97
98 dst = info->screen_buffer + p;
99
100 if (info->fbops->fb_sync)
101 info->fbops->fb_sync(info);
102
103 c = copy_from_user(dst, buf, count);
104 if (c)
105 err = -EFAULT;
106 ret = count - c;
107
108 *ppos += ret;
109
110 return ret ? ret : err;
111}
112EXPORT_SYMBOL_GPL(fb_sys_write);
113
114MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
115MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
116MODULE_LICENSE("GPL");