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1/*2 * linux/drivers/video/fb_sys_read.c - Generic file operations where3 * framebuffer is in system RAM4 *5 * Copyright (C) 2007 Antonino Daplas <adaplas@pol.net>6 *7 * This file is subject to the terms and conditions of the GNU General Public8 * License. See the file COPYING in the main directory of this archive9 * 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->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}59EXPORT_SYMBOL_GPL(fb_sys_read);60 61ssize_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}110EXPORT_SYMBOL_GPL(fb_sys_write);111 112MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");113MODULE_DESCRIPTION("Generic file read (fb in system RAM)");114MODULE_LICENSE("GPL");115