/* Copyright (C) 2005      David Decotigny, Thomas Petazzoni
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA.
 */
 #ifndef _SOS_CHARDEV_H_
 #define _SOS_CHARDEV_H_
 
 /**
  * @file chardev.h
  *
  * Interface between the VFS and the "character" devices. The
  * following functions provide the mechanisms to bind the "character
  * device" nodes (@see mknod) to their device driver.
  *
  * The VFS layer must be perceived as an uniform access library on top
  * of a set of specialized FS. The "chardev" layer is to be perceived
  * as a FS-agnostic layer on top of the FS that binds the special
  * "character device" nodes to a set of system-wide read/write/seek
  * functions.
  */
 
 #include "fs.h"
 
 /**
  * The fundamental callbacks for a character device: they are common
  * to all the character devices of the same class. One is free to do
  * whatever she likes with the "custom_data" of the opened file passed
  * as argument
  */
 struct sos_chardev_ops {
   /**
    * @note also called upon a "duplicate_opened_file", aka upon a
    * fork()
    * @note When this callback is called, of is NOT bound to any
    * nscache_node, so don't ever call any sos_fs_nscache_* function !
    * @note To get the fsnode associated to "of", don't call
    * sos_fs_nscache_get_fs_node(): it is already given by the "fsnode"
    * argument
    * @note MANDATORY !
    */
   sos_ret_t (*open)(struct sos_fs_node        * fsnode,
                     struct sos_fs_opened_file * of,
                     void * chardev_class_custom_data);
 
   /**
    * Called each time an opened "character device" is declared unused
    * by user space
    * @note Optional (might be NULL)
    */
   sos_ret_t (*close)(struct sos_fs_opened_file * of,
                      void * chardev_class_custom_data);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    */
   sos_ret_t (*seek)(struct sos_fs_opened_file *this,
                     sos_lsoffset_t offset,
                     sos_seek_whence_t whence,
                     /* out */ sos_lsoffset_t * result_position);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    */
   sos_ret_t (*read)(struct sos_fs_opened_file *this,
                     sos_uaddr_t dest_buf,
                     sos_size_t * /* in/out */len);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    * @note Please call sos_fs_mark_dirty() if disk contents is changed
    */
   sos_ret_t (*write)(struct sos_fs_opened_file *this,
                      sos_uaddr_t src_buf,
                      sos_size_t * /* in/out */len);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    * @note Please call sos_fs_mark_dirty() if disk contents is changed
    */
   sos_ret_t (*mmap)(struct sos_fs_opened_file *this,
                     sos_uaddr_t *uaddr, sos_size_t size,
                     sos_ui32_t access_rights,
                     sos_ui32_t flags,
                     sos_luoffset_t offset);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    * @note Please call sos_fs_mark_dirty() if disk contents is changed
    */
   sos_ret_t (*fcntl)(struct sos_fs_opened_file *this,
                      int req_id,
                      sos_ui32_t req_arg /* Usually: sos_uaddr_t */);
 
   /**
    * @note Optional (might be NULL), may block. Appropriate locking
    * MUST be implemented
    * @note Please call sos_fs_mark_dirty() if disk contents is changed
    */
   sos_ret_t (*ioctl)(struct sos_fs_opened_file *this,
                      int req_id,
                      sos_ui32_t req_arg /* Usually: sos_uaddr_t */);
 };
 
 
 /**
  * Associate the given set of operations to the given major number.
  *
  * @note Character device drivers are registered for a complete class
  * of character devices (up to 4 billion devices per class)
  */
 sos_ret_t sos_chardev_register_class (sos_ui32_t device_class,
                                       struct sos_chardev_ops * ops,
                                       void * chardev_class_custom_data);
 
 
 /**
  * Unbind the given set of operations with the given major number
  *
  * @return SOS_EBUSY when the character device is still opened by any
  * process.
  */
 sos_ret_t sos_chardev_unregister_class (sos_ui32_t device_class);
 
 
 /*
  * Callbacks restricted to fs.c internals
  */
 
 /**
  * Update the FS node ops_blockdev callbacks after an FS
  * allocate_new_node or fetch_node_from_disk, in order to point to
  * the block layer API functions
  */
 sos_ret_t sos_chardev_helper_ref_new_fsnode(struct sos_fs_node * this);
 sos_ret_t sos_chardev_helper_release_fsnode(struct sos_fs_node * this);
 
 #endif