linux/drivers/video/fb_sys_fops.c
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   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
  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;
  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}
  54EXPORT_SYMBOL_GPL(fb_sys_read);
  55
  56ssize_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}
 100EXPORT_SYMBOL_GPL(fb_sys_write);
 101
 102MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
 103MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
 104MODULE_LICENSE("GPL");
 105
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