/*
 * 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.
 *
 * Copyright (C) 2008 THALES Communications,  All Rights Reserved.
 * Author: F. LAMBERT
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/cdev.h>

#include <asm/io.h>
#include <asm/uaccess.h>

#include <asm-nios2/nios2.h>

#define DEBUG
#undef DEBUG

#define HRTIMER_BASE_ADDR            na_hrtimer_0
#define HRTIMER_SIZE                 4

MODULE_AUTHOR("Frederic LAMBERT");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Module for HiRes timer /dev/hrtimer");
MODULE_SUPPORTED_DEVICE("none");

#define HRTIMER_MAJOR                     251
#define HRTIMER_MINOR                     0

static int hrtimer_open(struct inode*, struct file*);
static int hrtimer_release(struct inode*, struct file*);
static int hrtimer_mmap(struct file *file, struct vm_area_struct * vma);
static unsigned long hrtimer_get_unmapped_area(struct file *file,
					   unsigned long addr,
					   unsigned long len,
					   unsigned long pgoff,
					   unsigned long flags);

static struct hrtimer_dev_t
{
  int __iomem*  membase;
  struct cdev   cdev;
} s_hrtimer_dev;

/* definitions, which functions are called for /dev/hrtimer */
static struct file_operations fops_hrtimer =
{
  .mmap    = hrtimer_mmap,
  .open    = hrtimer_open,
  .release = hrtimer_release,
  .get_unmapped_area = hrtimer_get_unmapped_area,
};

/* called when data device file is opened */
static int hrtimer_open(struct inode *inode, struct file *filp)
{
  struct hrtimer_dev_t *dev = container_of(inode->i_cdev, struct hrtimer_dev_t, cdev);

  filp->private_data = dev;

  return 0;
}

/* called when process closes data device file */
static int hrtimer_release(struct inode *inode, struct file *filp)
{
  return 0;
}

/* called when a process mmap from data file */
static int hrtimer_mmap(struct file *filp, struct vm_area_struct * vma)
{
  struct hrtimer_dev_t *dev = (struct hrtimer_dev_t*)filp->private_data;

  vma->vm_flags |= VM_MAYSHARE | VM_SHARED;

  vma->vm_start = (unsigned long)dev->membase;
  vma->vm_end = vma->vm_start + HRTIMER_SIZE;

  return 0;
}

static unsigned long hrtimer_get_unmapped_area(struct file *file,
					   unsigned long addr,
					   unsigned long len,
					   unsigned long pgoff,
					   unsigned long flags)
{
  return pgoff << PAGE_SHIFT;
}

static int __init mod_init(void)
{
  int res;
  dev_t devno = MKDEV(HRTIMER_MAJOR, HRTIMER_MINOR);
  struct hrtimer_dev_t *dev = &s_hrtimer_dev;

  cdev_init(&dev->cdev, &fops_hrtimer);
  dev->cdev.owner = THIS_MODULE;
  dev->membase = ioremap(HRTIMER_BASE_ADDR, HRTIMER_SIZE);

  res = register_chrdev_region(devno, 1, "hrtimer");
  if (res)
  {
    printk(KERN_NOTICE "Can't get major %d for HRTIMER", HRTIMER_MAJOR);
    return res;
  }
  res = cdev_add(&dev->cdev, devno, 1);
  if (res)
  {
    printk(KERN_NOTICE "Error %d adding HRTIMER", res);
    unregister_chrdev_region(devno, 1);
    return res;
  }
  printk(KERN_INFO "hrtimer: HiRes timer driver v0.0 (aug 2008) by frd66 at 0x%p\n",
  	dev->membase);

  return res;
}

/* exit the module */
static void __exit mod_exit(void)
{
  cdev_del(&s_hrtimer_dev.cdev);
  unregister_chrdev_region(MKDEV(HRTIMER_MAJOR, HRTIMER_MINOR), 1);
}

/* what are the module init/exit functions */
module_init(mod_init);
module_exit(mod_exit);