/*
   *    Filename: ks0108.c
   *     Version: 0.1.0
   * Description: ks0108 LCD Controller driver
   *     License: GPLv2
   *     Depends: parport
   *
   *      Author: Copyright (C) Miguel Ojeda Sandonis
   *        Date: 2006-10-31
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2 as
   *  published by the Free Software Foundation.
   *
   *  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
   *
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/delay.h>
  #include <linux/fs.h>
  #include <linux/io.h>
  #include <linux/parport.h>
  #include <linux/uaccess.h>
  #include <linux/ks0108.h>
  
  #define KS0108_NAME "ks0108"
  
  /*
   * Module Parameters
   */
  
  static unsigned int ks0108_port = CONFIG_KS0108_PORT;
  module_param(ks0108_port, uint, S_IRUGO);
  MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
  
  static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
  module_param(ks0108_delay, uint, S_IRUGO);
  MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
  
  /*
   * Device
   */
  
  static struct parport *ks0108_parport;
  static struct pardevice *ks0108_pardevice;
  
  /*
   * ks0108 Exported Commands (don't lock)
   *
   *   You _should_ lock in the top driver: This functions _should not_
   *   get race conditions in any way. Locking for each byte here would be
   *   so slow and useless.
   *
   *   There are not bit definitions because they are not flags,
   *   just arbitrary combinations defined by the documentation for each
   *   function in the ks0108 LCD controller. If you want to know what means
   *   a specific combination, look at the function's name.
   *
   *   The ks0108_writecontrol bits need to be reverted ^(0,1,3) because
   *   the parallel port also revert them using a "not" logic gate.
   */
  
  #define bit(n) (((unsigned char)1)<<(n))
  
  void ks0108_writedata(unsigned char byte)
  {
  	parport_write_data(ks0108_parport, byte);
  }
  
  void ks0108_writecontrol(unsigned char byte)
  {
  	udelay(ks0108_delay);
  	parport_write_control(ks0108_parport, byte ^ (bit(0) | bit(1) | bit(3)));
  }
  
  void ks0108_displaystate(unsigned char state)
  {
  	ks0108_writedata((state ? bit(0) : 0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5));
  }
  
  void ks0108_startline(unsigned char startline)
  {
  	ks0108_writedata(min(startline,(unsigned char)63) | bit(6) | bit(7));
  }
  
  void ks0108_address(unsigned char address)
  {
  	ks0108_writedata(min(address,(unsigned char)63) | bit(6));
  }
  
  void ks0108_page(unsigned char page)
  {
  	ks0108_writedata(min(page,(unsigned char)7) | bit(3) | bit(4) | bit(5) | bit(7));
  }
  
  EXPORT_SYMBOL_GPL(ks0108_writedata);
  EXPORT_SYMBOL_GPL(ks0108_writecontrol);
  EXPORT_SYMBOL_GPL(ks0108_displaystate);
  EXPORT_SYMBOL_GPL(ks0108_startline);
  EXPORT_SYMBOL_GPL(ks0108_address);
  EXPORT_SYMBOL_GPL(ks0108_page);
  
  /*
   * Is the module inited?
   */
  
  static unsigned char ks0108_inited;
  unsigned char ks0108_isinited(void)
  {
  	return ks0108_inited;
  }
  EXPORT_SYMBOL_GPL(ks0108_isinited);
  
  /*
   * Module Init & Exit
   */
  
  static int __init ks0108_init(void)
  {
  	int result;
  	int ret = -EINVAL;
  
  	ks0108_parport = parport_find_base(ks0108_port);
  	if (ks0108_parport == NULL) {
  		printk(KERN_ERR KS0108_NAME ": ERROR: "
  			"parport didn't find %i port
  ", ks0108_port);
  		goto none;
  	}
  
  	ks0108_pardevice = parport_register_device(ks0108_parport, KS0108_NAME,
  		NULL, NULL, NULL, PARPORT_DEV_EXCL, NULL);
  	if (ks0108_pardevice == NULL) {
  		printk(KERN_ERR KS0108_NAME ": ERROR: "
  			"parport didn't register new device
  ");
  		goto none;
  	}
  
  	result = parport_claim(ks0108_pardevice);
  	if (result != 0) {
  		printk(KERN_ERR KS0108_NAME ": ERROR: "
  			"can't claim %i parport, maybe in use
  ", ks0108_port);
  		ret = result;
  		goto registered;
  	}
  
  	ks0108_inited = 1;
  	return 0;
  
  registered:
  	parport_unregister_device(ks0108_pardevice);
  
  none:
  	return ret;
  }
  
  static void __exit ks0108_exit(void)
  {
  	parport_release(ks0108_pardevice);
  	parport_unregister_device(ks0108_pardevice);
  }
  
  module_init(ks0108_init);
  module_exit(ks0108_exit);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
  MODULE_DESCRIPTION("ks0108 LCD Controller driver");