Eric Lee / smarc-fsl-linux-kernel

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drivers/video/fb_sys_fops.c 2.03 KB
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09aaf268e   Antonino A. Daplas   fbdev: add fb_rea... 
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  /*
   * linux/drivers/video/fb_sys_read.c - Generic file operations where
   * framebuffer is in system RAM
   *
   * Copyright (C) 2007 Antonino Daplas <adaplas@pol.net>
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file COPYING in the main directory of this archive
   * for more details.
   *
   */
  #include <linux/fb.h>
  #include <linux/module.h>
84902b7af   Krzysztof Helt   fbdev: change asm... 
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  #include <linux/uaccess.h>
09aaf268e   Antonino A. Daplas   fbdev: add fb_rea... 
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  ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count,
  		    loff_t *ppos)
  {
  	unsigned long p = *ppos;
  	void *src;
  	int err = 0;
  	unsigned long total_size;
  
  	if (info->state != FBINFO_STATE_RUNNING)
  		return -EPERM;
  
  	total_size = info->screen_size;
  
  	if (total_size == 0)
  		total_size = info->fix.smem_len;
  
  	if (p >= total_size)
  		return 0;
  
  	if (count >= total_size)
  		count = total_size;
  
  	if (count + p > total_size)
  		count = total_size - p;
  
  	src = (void __force *)(info->screen_base + p);
  
  	if (info->fbops->fb_sync)
  		info->fbops->fb_sync(info);
  
  	if (copy_to_user(buf, src, count))
  		err = -EFAULT;
  
  	if  (!err)
  		*ppos += count;
  
  	return (err) ? err : count;
  }
  EXPORT_SYMBOL_GPL(fb_sys_read);
  
  ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
  		     size_t count, loff_t *ppos)
  {
  	unsigned long p = *ppos;
  	void *dst;
  	int err = 0;
  	unsigned long total_size;
  
  	if (info->state != FBINFO_STATE_RUNNING)
  		return -EPERM;
  
  	total_size = info->screen_size;
  
  	if (total_size == 0)
  		total_size = info->fix.smem_len;
  
  	if (p > total_size)
  		return -EFBIG;
  
  	if (count > total_size) {
  		err = -EFBIG;
  		count = total_size;
  	}
  
  	if (count + p > total_size) {
  		if (!err)
  			err = -ENOSPC;
  
  		count = total_size - p;
  	}
  
  	dst = (void __force *) (info->screen_base + p);
  
  	if (info->fbops->fb_sync)
  		info->fbops->fb_sync(info);
  
  	if (copy_from_user(dst, buf, count))
  		err = -EFAULT;
  
  	if  (!err)
  		*ppos += count;
  
  	return (err) ? err : count;
  }
  EXPORT_SYMBOL_GPL(fb_sys_write);
  
  MODULE_AUTHOR("Antonino Daplas <adaplas@pol.net>");
  MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
  MODULE_LICENSE("GPL");