/*
 * File Name : mmap.c
 * This includes the functions required for the memeory mapping system call.
 * Work done for final project, Course: CIS5930
 * Course Name: Linux Kernel Programming & Device Driver Programming
 * Written by: Veena Adityan and Arthi Gokarn.
 * Submitted to: Dr. Baker
 * Date: 06/20/2003
 * Copyright 2003 
 */
#include "pixelsmart.h"

/*
 * Common VMA ops.
 */

extern struct pixelsmart *psmart;

void pixelsmart_vma_open(struct vm_area_struct *vma)
{ MOD_INC_USE_COUNT; }

void pixelsmart_vma_close(struct vm_area_struct *vma)
{ MOD_DEC_USE_COUNT; }

/*
 * To prevent extension of the mapping, cause a bus signal to be sent to the
 * faulting process. 
 */
struct page *pixelsmart_vma_nopage(struct vm_area_struct *vma,
                unsigned long address, int write_access)
{
  return NOPAGE_SIGBUS;
}


static struct vm_operations_struct pixelsmart_vm_ops = {
    open:    pixelsmart_vma_open,
    close:   pixelsmart_vma_close,
    nopage:  pixelsmart_vma_nopage,
    
};

/*
 * Called by the memory map system call 
 */
int pixelsmart_mmap(struct file *filp, struct vm_area_struct *vma)
{
  struct video_device *dev = video_devdata(filp);
  struct pixelsmart *pstv = dev->priv;
  
  unsigned long off ;
  unsigned long physical;
  unsigned long vsize;
  unsigned long psize;

  if (down_interruptible(&pstv->sem))
     return -ERESTARTSYS;
  off = vma->vm_pgoff << PAGE_SHIFT;
  physical = psmart->pixelsmart_adr + off;
  vsize = vma->vm_end - vma->vm_start;
#ifdef DEBUG
  printk("<1>mmap 4 vsize= %ld\n, vm_end = %ld, vm_start = %ld, vm_pgoff=%ld",vsize,vma->vm_end,vma->vm_start,vma->vm_pgoff);
#endif
  psize = 0x4000 - off;
  if(vsize > psize){
    up(&pstv->sem);
    return -EINVAL;
  }
  if(remap_page_range(vma->vm_start, physical , vsize, vma->vm_page_prot)){
    up(&pstv->sem);
    return -EAGAIN;
  }
  vma->vm_ops = &pixelsmart_vm_ops;
  pixelsmart_vma_open(vma);
  up(&pstv->sem);
  return 0;
}