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