| 1 | /* |
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| 2 | * linux/drivers/video/fb_sys_read.c - Generic file operations where |
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| 3 | * framebuffer is in system RAM |
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| 4 | * |
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| 5 | * Copyright (C) 2007 Antonino Daplas <adaplas@pol.net> |
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| 6 | * |
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| 7 | * This file is subject to the terms and conditions of the GNU General Public |
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| 8 | * License. See the file COPYING in the main directory of this archive |
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| 9 | * for more details. |
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| 10 | * |
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| 11 | */ |
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| 12 | #include <linux/fb.h> |
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| 13 | #include <linux/module.h> |
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| 14 | #include <linux/uaccess.h> |
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| 15 | |
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| 16 | ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count, |
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| 17 | loff_t *ppos) |
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| 18 | { |
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| 19 | unsigned long p = *ppos; |
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| 20 | void *src; |
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| 21 | int err = 0; |
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| 22 | unsigned long total_size, c; |
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| 23 | ssize_t ret; |
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| 24 | |
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| 25 | if (!(info->flags & FBINFO_VIRTFB)) |
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| 26 | fb_warn_once(info, "Framebuffer is not in virtual address space." ); |
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| 27 | |
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| 28 | if (!info->screen_buffer) |
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| 29 | return -ENODEV; |
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| 30 | |
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| 31 | total_size = info->screen_size; |
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| 32 | |
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| 33 | if (total_size == 0) |
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| 34 | total_size = info->fix.smem_len; |
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| 35 | |
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| 36 | if (p >= total_size) |
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| 37 | return 0; |
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| 38 | |
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| 39 | if (count >= total_size) |
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| 40 | count = total_size; |
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| 41 | |
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| 42 | if (count + p > total_size) |
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| 43 | count = total_size - p; |
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| 44 | |
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| 45 | src = info->screen_buffer + p; |
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| 46 | |
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| 47 | if (info->fbops->fb_sync) |
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| 48 | info->fbops->fb_sync(info); |
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| 49 | |
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| 50 | c = copy_to_user(to: buf, from: src, n: count); |
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| 51 | if (c) |
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| 52 | err = -EFAULT; |
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| 53 | ret = count - c; |
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| 54 | |
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| 55 | *ppos += ret; |
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| 56 | |
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| 57 | return ret ? ret : err; |
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| 58 | } |
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| 59 | EXPORT_SYMBOL_GPL(fb_sys_read); |
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| 60 | |
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| 61 | ssize_t fb_sys_write(struct fb_info *info, const char __user *buf, |
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| 62 | size_t count, loff_t *ppos) |
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| 63 | { |
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| 64 | unsigned long p = *ppos; |
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| 65 | void *dst; |
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| 66 | int err = 0; |
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| 67 | unsigned long total_size, c; |
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| 68 | size_t ret; |
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| 69 | |
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| 70 | if (!(info->flags & FBINFO_VIRTFB)) |
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| 71 | fb_warn_once(info, "Framebuffer is not in virtual address space." ); |
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| 72 | |
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| 73 | if (!info->screen_buffer) |
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| 74 | return -ENODEV; |
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| 75 | |
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| 76 | total_size = info->screen_size; |
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| 77 | |
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| 78 | if (total_size == 0) |
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| 79 | total_size = info->fix.smem_len; |
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| 80 | |
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| 81 | if (p > total_size) |
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| 82 | return -EFBIG; |
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| 83 | |
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| 84 | if (count > total_size) { |
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| 85 | err = -EFBIG; |
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| 86 | count = total_size; |
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| 87 | } |
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| 88 | |
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| 89 | if (count + p > total_size) { |
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| 90 | if (!err) |
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| 91 | err = -ENOSPC; |
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| 92 | |
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| 93 | count = total_size - p; |
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| 94 | } |
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| 95 | |
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| 96 | dst = info->screen_buffer + p; |
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| 97 | |
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| 98 | if (info->fbops->fb_sync) |
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| 99 | info->fbops->fb_sync(info); |
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| 100 | |
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| 101 | c = copy_from_user(to: dst, from: buf, n: count); |
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| 102 | if (c) |
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| 103 | err = -EFAULT; |
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| 104 | ret = count - c; |
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| 105 | |
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| 106 | *ppos += ret; |
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| 107 | |
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| 108 | return ret ? ret : err; |
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| 109 | } |
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| 110 | EXPORT_SYMBOL_GPL(fb_sys_write); |
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| 111 | |
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| 112 | MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>" ); |
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| 113 | MODULE_DESCRIPTION("Generic file read (fb in system RAM)" ); |
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| 114 | MODULE_LICENSE("GPL" ); |
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| 115 | |
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