drivers/video/fb_sys_fops.c

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