Line data    Source code

       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             : 
      16           0 : ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count,
      17             :                     loff_t *ppos)
      18             : {
      19           0 :         unsigned long p = *ppos;
      20             :         void *src;
      21           0 :         int err = 0;
      22             :         unsigned long total_size, c;
      23             :         ssize_t ret;
      24             : 
      25           0 :         if (!info->screen_buffer)
      26             :                 return -ENODEV;
      27             : 
      28           0 :         total_size = info->screen_size;
      29             : 
      30           0 :         if (total_size == 0)
      31           0 :                 total_size = info->fix.smem_len;
      32             : 
      33           0 :         if (p >= total_size)
      34             :                 return 0;
      35             : 
      36           0 :         if (count >= total_size)
      37           0 :                 count = total_size;
      38             : 
      39           0 :         if (count + p > total_size)
      40           0 :                 count = total_size - p;
      41             : 
      42           0 :         src = info->screen_buffer + p;
      43             : 
      44           0 :         if (info->fbops->fb_sync)
      45           0 :                 info->fbops->fb_sync(info);
      46             : 
      47           0 :         c = copy_to_user(buf, src, count);
      48           0 :         if (c)
      49           0 :                 err = -EFAULT;
      50           0 :         ret = count - c;
      51             : 
      52           0 :         *ppos += ret;
      53             : 
      54           0 :         return ret ? ret : err;
      55             : }
      56             : EXPORT_SYMBOL_GPL(fb_sys_read);
      57             : 
      58           0 : ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
      59             :                      size_t count, loff_t *ppos)
      60             : {
      61           0 :         unsigned long p = *ppos;
      62             :         void *dst;
      63           0 :         int err = 0;
      64             :         unsigned long total_size, c;
      65             :         size_t ret;
      66             : 
      67           0 :         if (!info->screen_buffer)
      68             :                 return -ENODEV;
      69             : 
      70           0 :         total_size = info->screen_size;
      71             : 
      72           0 :         if (total_size == 0)
      73           0 :                 total_size = info->fix.smem_len;
      74             : 
      75           0 :         if (p > total_size)
      76             :                 return -EFBIG;
      77             : 
      78           0 :         if (count > total_size) {
      79           0 :                 err = -EFBIG;
      80           0 :                 count = total_size;
      81             :         }
      82             : 
      83           0 :         if (count + p > total_size) {
      84           0 :                 if (!err)
      85           0 :                         err = -ENOSPC;
      86             : 
      87           0 :                 count = total_size - p;
      88             :         }
      89             : 
      90           0 :         dst = info->screen_buffer + p;
      91             : 
      92           0 :         if (info->fbops->fb_sync)
      93           0 :                 info->fbops->fb_sync(info);
      94             : 
      95           0 :         c = copy_from_user(dst, buf, count);
      96           0 :         if (c)
      97           0 :                 err = -EFAULT;
      98           0 :         ret = count - c;
      99             : 
     100           0 :         *ppos += ret;
     101             : 
     102           0 :         return ret ? ret : err;
     103             : }
     104             : EXPORT_SYMBOL_GPL(fb_sys_write);
     105             : 
     106             : MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
     107             : MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
     108             : MODULE_LICENSE("GPL");