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
fb_sys_read(struct fb_info * info,char __user * buf,size_t count,loff_t * ppos)16 ssize_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 }
54 EXPORT_SYMBOL_GPL(fb_sys_read);
55
fb_sys_write(struct fb_info * info,const char __user * buf,size_t count,loff_t * ppos)56 ssize_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 }
100 EXPORT_SYMBOL_GPL(fb_sys_write);
101
102 MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
103 MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
104 MODULE_LICENSE("GPL");
105