path: root/drv_HD44780.c

/* $Id: drv_HD44780.c,v 1.44 2005/01/29 09:30:56 reinelt Exp $
 *
 * new style driver for HD44780-based displays
 *
 * Copyright (C) 2003 Michael Reinelt <reinelt@eunet.at>
 * Copyright (C) 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
 *
 * Modification for 4-Bit mode
 * Copyright (C) 2003 Martin Hejl (martin@hejl.de)
 *
 * Modification for 2nd controller support
 * Copyright (C) 2003 Jesse Brook Kovach <jkovach@wam.umd.edu>
 *
 * This file is part of LCD4Linux.
 *
 * LCD4Linux 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, or (at your option)
 * any later version.
 *
 * LCD4Linux 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: drv_HD44780.c,v $
 * Revision 1.44  2005/01/29 09:30:56  reinelt
 * minor HD44780 cleanups
 *
 * Revision 1.43  2005/01/18 06:30:23  reinelt
 * added (C) to all copyright statements
 *
 * Revision 1.42  2005/01/17 06:38:48  reinelt
 * info about backlight and brightness
 *
 * Revision 1.41  2005/01/17 06:29:24  reinelt
 * added software-controlled backlight support to HD44780
 *
 * Revision 1.40  2004/11/30 05:01:25  reinelt
 * removed compiler warnings for deactivated i2c bus
 *
 * Revision 1.39  2004/10/17 09:24:31  reinelt
 * I2C support for HD44780 displays by Luis (does not work by now)
 *
 * Revision 1.38  2004/09/19 09:31:19  reinelt
 * HD44780 busy flag checking improved: fall back to busy-waiting if too many errors occur
 *
 * Revision 1.37  2004/09/18 15:58:57  reinelt
 * even more HD44780 cleanups, hardwiring for LCM-162
 *
 * Revision 1.36  2004/09/18 10:57:29  reinelt
 * more parport/i2c cleanups
 *
 * Revision 1.35  2004/09/18 09:48:29  reinelt
 * HD44780 cleanup and prepararation for I2C backend
 * LCM-162 submodel framework
 *
 * Revision 1.34  2004/09/18 08:22:59  reinelt
 * drv_generic_parport_status() to read status lines
 *
 * Revision 1.33  2004/08/29 13:03:41  reinelt
 *
 * added RouterBoard driver
 *
 * Revision 1.32  2004/06/26 12:04:59  reinelt
 *
 * uh-oh... the last CVS log message messed up things a lot...
 *
 * Revision 1.31  2004/06/26 09:27:20  reinelt
 *
 * added '-W' to CFLAGS
 * changed all C++ comments to C ones
 * cleaned up a lot of signed/unsigned mistakes
 *
 * Revision 1.30  2004/06/20 10:09:54  reinelt
 *
 * 'const'ified the whole source
 *
 * Revision 1.29  2004/06/06 06:51:59  reinelt
 *
 * do not display end splash screen if quiet=1
 *
 * Revision 1.28  2004/06/05 06:41:39  reinelt
 *
 * chancged splash screen again
 *
 * Revision 1.27  2004/06/05 06:13:11  reinelt
 *
 * splash screen for all text-based display drivers
 *
 * Revision 1.26  2004/06/02 10:09:22  reinelt
 *
 * splash screen for HD44780
 *
 * Revision 1.25  2004/06/02 09:41:19  reinelt
 *
 * prepared support for startup splash screen
 *
 * Revision 1.24  2004/06/01 06:45:29  reinelt
 *
 * some Fixme's processed
 * documented some code
 *
 * Revision 1.23  2004/05/31 05:38:02  reinelt
 *
 * fixed possible bugs with user-defined chars (clear high bits)
 * thanks to Andy Baxter for debugging the MilfordInstruments driver!
 *
 * Revision 1.22  2004/05/27 03:39:47  reinelt
 *
 * changed function naming scheme to plugin::function
 *
 * Revision 1.21  2004/05/26 11:37:36  reinelt
 *
 * Curses driver ported.
 *
 * Revision 1.20  2004/05/22 04:23:49  reinelt
 *
 * removed 16*x fix again (next time think before commit :-)
 *
 * Revision 1.19  2004/05/22 04:21:02  reinelt
 *
 * fix for display RAM layout on 16x4 displays (thanks to toxicated101)
 *
 * Revision 1.18  2004/03/20 07:31:32  reinelt
 * support for HD66712 (which has a different RAM layout)
 * further threading development
 *
 * Revision 1.17  2004/03/19 09:17:46  reinelt
 *
 * removed the extra 'goto' function, row and col are additional parameters
 * of the write() function now.
 *
 * Revision 1.16  2004/03/11 06:39:58  reinelt
 * big patch from Martin:
 * - reuse filehandles
 * - memory leaks fixed
 * - earlier busy-flag checking with HD44780
 * - reuse memory for strings in RESULT and hash
 * - netdev_fast to wavid time-consuming regex
 *
 * Revision 1.15  2004/03/03 03:47:04  reinelt
 * big patch from Martin Hejl:
 * - use qprintf() where appropriate
 * - save CPU cycles on gettimeofday()
 * - add quit() functions to free allocated memory
 * - fixed lots of memory leaks
 *
 * Revision 1.14  2004/03/01 04:29:51  reinelt
 * cfg_number() returns -1 on error, 0 if value not found (but default val used),
 *  and 1 if value was used from the configuration.
 * HD44780 driver adopted to new cfg_number()
 * Crystalfontz 631 driver nearly finished
 *
 * Revision 1.13  2004/02/15 21:43:43  reinelt
 * T6963 driver nearly finished
 * framework for graphic displays done
 * i2c_sensors patch from Xavier
 * some more old generation files removed
 *
 * Revision 1.12  2004/02/14 11:56:17  reinelt
 * M50530 driver ported
 * changed lots of 'char' to 'unsigned char'
 *
 * Revision 1.11  2004/02/04 19:10:51  reinelt
 * Crystalfontz driver nearly finished
 *
 * Revision 1.10  2004/02/02 05:22:16  reinelt
 * Brightness fpr Noritake Displays avaliable as a plugin
 *
 * Revision 1.9  2004/02/01 11:51:22  hejl
 * Fixes for busy flag
 *
 * Revision 1.8  2004/02/01 08:05:12  reinelt
 * Crystalfontz 633 extensions (CRC checking and stuff)
 * Models table for HD44780
 * Noritake VFD BVrightness patch from Bill Paxton
 *
 * Revision 1.7  2004/01/30 07:12:35  reinelt
 * HD44780 busy-flag support from Martin Hejl
 * loadavg() uClibc replacement from Martin Heyl
 * round() uClibc replacement from Martin Hejl
 * warning in i2c_sensors fixed
 * [
 *
 * Revision 1.6  2004/01/29 04:40:02  reinelt
 * every .c file includes "config.h" now
 *
 * Revision 1.5  2004/01/23 07:04:17  reinelt
 * icons finished!
 *
 * Revision 1.4  2004/01/23 04:53:48  reinelt
 * icon widget added (not finished yet!)
 *
 * Revision 1.3  2004/01/22 07:57:45  reinelt
 * several bugs fixed where segfaulting on layout>display
 * Crystalfontz driver optimized, 632 display already works
 *
 * Revision 1.2  2004/01/21 06:39:27  reinelt
 * HD44780 missed the "clear display' sequence
 * asc255bug handling added
 * HD44780 tested, works here!
 *
 * Revision 1.1  2004/01/20 15:32:49  reinelt
 * first version of Next Generation HD44780 (untested! but it compiles...)
 * some cleanup in the other drivers
 *
 */

/* 
 *
 * exported fuctions:
 *
 * struct DRIVER drv_HD44780
 *
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/ioctl.h>

/* Fixme: I2C support does not compile */
#if 0
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#endif

#include "debug.h"
#include "cfg.h"
#include "udelay.h"
#include "qprintf.h"
#include "timer.h"
#include "plugin.h"
#include "widget.h"
#include "widget_text.h"
#include "widget_icon.h"
#include "widget_bar.h"
#include "drv.h"
#include "drv_generic_text.h"
#include "drv_generic_parport.h"

static char Name[]="HD44780";

static int Bus;
static int Model;
static int Capabilities;


/* low level communication timings [nanoseconds]
 * as these values differ from spec to spec,
 * we use the worst-case values.
 */

#define T_CYCLE 1000 /* Enable cycle time */
#define T_PW     450 /* Enable pulse width */
#define T_AS      60 /* Address setup time */
#define T_H       40 /* Data hold time */
#define T_AH      20 /* Address hold time */


/* HD44780 execution timings [microseconds]
 * as these values differ from spec to spec,
 * we use the worst-case values.
 */

#define T_INIT1 4100 /* first init sequence:  4.1 msec */
#define T_INIT2  100 /* second init sequence: 100 usec */
#define T_EXEC    80 /* normal execution time */
#define T_WRCG   120 /* CG RAM Write */
#define T_CLEAR 1680 /* Clear Display */


static int Bits=0;
static int numControllers = 0;
static int allControllers = 0;
static int currController = 0;

static unsigned char SIGNAL_RW;
static unsigned char SIGNAL_RS;
static unsigned char SIGNAL_ENABLE;
static unsigned char SIGNAL_ENABLE2;
static unsigned char SIGNAL_BACKLIGHT;
static unsigned char SIGNAL_GPO;

/* maximum time to wait for the busy-flag (in usec) */
#define MAX_BUSYFLAG_WAIT 10000

/* maximum busy flag errors before falling back to busy-waiting */
#define MAX_BUSYFLAG_ERRORS 20

/* flag for busy-waiting vs. busy flag checking */
static int UseBusy = 0;


/* Fixme: GPO's not yet implemented */
static int GPOS;
/* static int GPO=0; */


typedef struct {
  int type;
  char *name;
  int capabilities;
} MODEL;

#define CAP_PARPORT    (1<<0)
#define CAP_I2C        (1<<1)
#define CAP_GPO        (1<<2)
#define CAP_BACKLIGHT  (1<<3)
#define CAP_BRIGHTNESS (1<<4)
#define CAP_BUSY4BIT   (1<<5)
#define CAP_HD66712    (1<<6)
#define CAP_LCM162     (1<<7)

#define BUS_PP  CAP_PARPORT
#define BUS_I2C CAP_I2C


static MODEL Models[] = {
  { 0x01, "generic",  CAP_PARPORT|CAP_I2C|CAP_GPO|CAP_BACKLIGHT },
  { 0x02, "Noritake", CAP_PARPORT|CAP_I2C|CAP_GPO|CAP_BRIGHTNESS },
  { 0x03, "Soekris",  CAP_PARPORT|CAP_BUSY4BIT },
  { 0x04, "HD66712",  CAP_PARPORT|CAP_I2C|CAP_GPO|CAP_BACKLIGHT|CAP_HD66712 },
  { 0x05, "LCM-162",  CAP_PARPORT|CAP_LCM162 },
  { 0xff, "Unknown",  0 }
};


/* handle for I2C device */
static int i2c_device;



/****************************************/
/***  generic functions               ***/
/****************************************/

static int  (*drv_HD_load)    (const char *section);
static void (*drv_HD_command) (const unsigned char controller, const unsigned char cmd, const int delay);
static void (*drv_HD_data)    (const unsigned char controller, const char *string, const int len, const int delay);
static void (*drv_HD_stop)    (void);



/****************************************/
/***  parport dependant functions     ***/
/****************************************/

static void drv_HD_PP_busy(const int controller)
{
  static unsigned int errors = 0;

  unsigned char enable;
  unsigned char data=0xFF;
  unsigned char busymask;
  unsigned char ctrlmask;
  unsigned int  counter;
  
  if (Bits==8) {
    busymask = 0x80;
  } else {
    /* Since in 4-Bit mode DB0 on the parport is mapped to DB4 on the LCD
     * (and consequently, DB3 on the partport is mapped to DB7 on the LCD)
     * we need to listen for DB3 on the parport to go low
     */
    busymask = 0x08;
  }

  ctrlmask = 0x02;
  while (ctrlmask > 0 ) {
    
    if (controller & ctrlmask) {

      enable = 0;
      if      (ctrlmask & 0x01) enable = SIGNAL_ENABLE; 
      else if (ctrlmask & 0x02) enable = SIGNAL_ENABLE2;
      
      /* set data-lines to input*/
      drv_generic_parport_direction(1);
      
      if (Bits==8) {
        /* Set RW, clear RS */
        drv_generic_parport_control(SIGNAL_RW|SIGNAL_RS,SIGNAL_RW);
      } else {
        drv_generic_parport_data(SIGNAL_RW);
      }
      
      /* Address set-up time */
      ndelay(T_AS);
      
      /* rise ENABLE */
      if (Bits==8) {
        drv_generic_parport_control(enable,enable);
      } else {
        drv_generic_parport_data(SIGNAL_RW|enable);
      }

      counter=0;
      while (1) {
        /* read the busy flag */
        data = drv_generic_parport_read();
        if ((data & busymask) == 0) {
	  errors = 0;
	  break;
	}

        /* make sure we don't wait forever
        - but only check after 5 iterations
        that way, we won't slow down normal mode
        (where we don't need the timeout anyway) */
        counter++;

        if (counter >= 5) {
          struct timeval now, end;

          if (counter == 5) {
            /* determine the time when the timeout has expired */
            gettimeofday (&end, NULL);
            end.tv_usec += MAX_BUSYFLAG_WAIT;
            while (end.tv_usec > 1000000) {
              end.tv_usec -= 1000000;
              end.tv_sec++;
            }
          }

          /* get the current time */
          gettimeofday(&now, NULL);
          if (now.tv_sec == end.tv_sec ? now.tv_usec >= end.tv_usec : now.tv_sec >= end.tv_sec) {
            error ("%s: timeout waiting for busy flag on controller %x (%x)", Name, ctrlmask, data);
	    if (++errors >= MAX_BUSYFLAG_ERRORS) {
	      error ("%s: too many busy flag failures, turning off busy flag checking.", Name);
	      UseBusy = 0;
	    }
            break;
          }
        }
      }

      /* RS=low, RW=low, EN=low */
      if (Bits == 8) {
        /* Lower EN */
        drv_generic_parport_control(enable,0);

        /* Address hold time */
        ndelay(T_AH);

        drv_generic_parport_control(SIGNAL_RW|SIGNAL_RS,0);
      } else {
        /* Lower EN */
        drv_generic_parport_data(SIGNAL_RW);
        ndelay(T_AH);
        drv_generic_parport_data(0);
      }

      /* set data-lines to output*/
      drv_generic_parport_direction(0);
    }
    ctrlmask >>= 1;
  }
}


static void drv_HD_PP_nibble(const unsigned char controller, const unsigned char nibble)
{
  unsigned char enable;

  /* enable signal: 'controller' is a bitmask */
  /* bit 0 .. send to controller #0 */
  /* bit 1 .. send to controller #1 */
  /* so we can send a byte to both controllers at the same time! */
  enable=0;
  if (controller&0x01) enable|=SIGNAL_ENABLE;
  if (controller&0x02) enable|=SIGNAL_ENABLE2;
  
  /* clear ENABLE */
  /* put data on DB1..DB4 */
  /* nibble already contains RS bit! */
  drv_generic_parport_data(nibble);

  /* Address set-up time */
  ndelay(T_AS);
  
  /* rise ENABLE */
  drv_generic_parport_data(nibble | enable);
  
  /* Enable pulse width */
  ndelay(T_PW);

  /* lower ENABLE */
  drv_generic_parport_data(nibble);
}


static void drv_HD_PP_byte (const unsigned char controller, const unsigned char data, const unsigned char RS)
{
  /* send high nibble of the data */
  drv_HD_PP_nibble (controller, ((data>>4)&0x0f)|RS);

  /* Make sure we honour T_CYCLE */
  ndelay(T_CYCLE-T_AS-T_PW);

  /* send low nibble of the data */
  drv_HD_PP_nibble(controller, (data&0x0f)|RS);
}


static void drv_HD_PP_command (const unsigned char controller, const unsigned char cmd, const int delay)
{
  unsigned char enable;

  if (UseBusy) drv_HD_PP_busy(controller);

  if (Bits==8) {
    
    /* enable signal: 'controller' is a bitmask */
    /* bit 0 .. send to controller #0 */
    /* bit 1 .. send to controller #1 */
    /* so we can send a byte to both controllers at the same time! */
    enable=0;
    if (controller&0x01) enable|=SIGNAL_ENABLE;
    if (controller&0x02) enable|=SIGNAL_ENABLE2;
    
    /* put data on DB1..DB8 */
    drv_generic_parport_data (cmd);
  
    /* clear RW and RS */
    drv_generic_parport_control (SIGNAL_RW | SIGNAL_RS, 0);
    
    /* Address set-up time */
    ndelay(T_AS);

    /* send command */
    drv_generic_parport_toggle (enable, 1, T_PW);
    
  } else {

    drv_HD_PP_byte (controller, cmd, 0);

  }
  
  /* wait for command completion */
  if (!UseBusy) udelay(delay);

}


static void drv_HD_PP_data (const unsigned char controller, const char *string, const int len, const int delay)
{
  int l = len;
  unsigned char enable;

  /* sanity check */
  if (len<=0) return;

  if (Bits==8) {

    /* enable signal: 'controller' is a bitmask */
    /* bit 0 .. send to controller #0 */
    /* bit 1 .. send to controller #1 */
    /* so we can send a byte to both controllers at the same time! */
    enable=0;
    if (controller&0x01) enable|=SIGNAL_ENABLE;
    if (controller&0x02) enable|=SIGNAL_ENABLE2;
    
    if (!UseBusy) {
      /* clear RW, set RS */
      drv_generic_parport_control (SIGNAL_RW | SIGNAL_RS, SIGNAL_RS);
      /* Address set-up time */
      ndelay(T_AS);
    }
    
    while (l--) {

      if (UseBusy) {
	drv_HD_PP_busy(controller);
	/* clear RW, set RS */
	drv_generic_parport_control (SIGNAL_RW | SIGNAL_RS, SIGNAL_RS);
	/* Address set-up time */
	ndelay(T_AS);
      }
      
      /* put data on DB1..DB8 */
      drv_generic_parport_data (*(string++));
      
      /* send command */
      drv_generic_parport_toggle (enable, 1, T_PW);
      
      /* wait for command completion */
      if (!UseBusy) udelay(delay);
    }
    
  } else { /* 4 bit mode */
    
    while (l--) {
      if (UseBusy) drv_HD_PP_busy(controller);

      /* send data with RS enabled */
      drv_HD_PP_byte (controller, *(string++), SIGNAL_RS);
      
      /* wait for command completion */
      if (!UseBusy) udelay(delay);
    }
  }
}


static int drv_HD_PP_load (const char *section)
{
  if (cfg_number(section, "Bits", 8, 4, 8, &Bits)<0) return -1;
  if (Bits!=4 && Bits!=8) {
    error ("%s: bad %s.Bits '%d' from %s, should be '4' or '8'", Name, section, Bits, cfg_source());
    return -1;
  }    
  
  /* LCM-162 only supports 8-bit-mode */
  if (Capabilities & CAP_LCM162 && Bits != 8) {
    error ("%s: Model '%s' does not support %d bit mode!", Name, Models[Model].name, Bits);
    Bits = 8;
  }
  info ("%s: using %d bit mode", Name, Bits);
  
  if (drv_generic_parport_open(section, Name) != 0) {
    error ("%s: could not initialize parallel port!", Name);
    return -1;
  }

  /* Soft-Wiring */
  if (Capabilities & CAP_LCM162) {
    /* the LCM-162 is hardwired */
    if ((SIGNAL_RS        = drv_generic_parport_hardwire_ctrl ("RS",        "SELECT")) == 0xff) return -1;
    if ((SIGNAL_RW        = drv_generic_parport_hardwire_ctrl ("RW",        "INIT"  )) == 0xff) return -1;
    if ((SIGNAL_ENABLE    = drv_generic_parport_hardwire_ctrl ("ENABLE",    "AUTOFD")) == 0xff) return -1;
    if ((SIGNAL_ENABLE2   = drv_generic_parport_hardwire_ctrl ("ENABLE2",   "GND"   )) == 0xff) return -1;
    if ((SIGNAL_BACKLIGHT = drv_generic_parport_hardwire_ctrl ("BACKLIGHT", "GND"   )) == 0xff) return -1;
    if ((SIGNAL_GPO       = drv_generic_parport_hardwire_ctrl ("GPO",       "GND"   )) == 0xff) return -1;
  } else {
    if (Bits==8) {
      if ((SIGNAL_RS        = drv_generic_parport_wire_ctrl ("RS",      "AUTOFD")) == 0xff) return -1;
      if ((SIGNAL_RW        = drv_generic_parport_wire_ctrl ("RW",      "GND"   )) == 0xff) return -1;
      if ((SIGNAL_ENABLE    = drv_generic_parport_wire_ctrl ("ENABLE",  "STROBE")) == 0xff) return -1;
      if ((SIGNAL_ENABLE2   = drv_generic_parport_wire_ctrl ("ENABLE2", "GND"   )) == 0xff) return -1;
    } else {
      if ((SIGNAL_RS        = drv_generic_parport_wire_data ("RS",      "DB4")) == 0xff) return -1;
      if ((SIGNAL_RW        = drv_generic_parport_wire_data ("RW",      "DB5")) == 0xff) return -1;
      if ((SIGNAL_ENABLE    = drv_generic_parport_wire_data ("ENABLE",  "DB6")) == 0xff) return -1;
      if ((SIGNAL_ENABLE2   = drv_generic_parport_wire_data ("ENABLE2", "GND")) == 0xff) return -1;
    }
    /* backlight and GPO are always control signals */
    if ((SIGNAL_BACKLIGHT = drv_generic_parport_wire_ctrl ("BACKLIGHT", "GND"   )) == 0xff) return -1;
    if ((SIGNAL_GPO       = drv_generic_parport_wire_ctrl ("GPO",       "GND"   )) == 0xff) return -1;
  }

  /* clear capabilities if corresponding signal is GND */
  if (SIGNAL_BACKLIGHT == 0) {
    Capabilities &= ~CAP_BACKLIGHT;
  }
  if (SIGNAL_GPO == 0) {
    Capabilities &= ~CAP_GPO;
  }


  /* clear all signals */
  if (Bits == 8) {
    drv_generic_parport_control (SIGNAL_RS|SIGNAL_RW|SIGNAL_ENABLE|SIGNAL_ENABLE2|SIGNAL_BACKLIGHT|SIGNAL_GPO, 0);
  } else {
    drv_generic_parport_data (0);
  }
  
  /* set direction: write */
  drv_generic_parport_direction (0);
  
  /* initialize *both* displays */
  if (Bits==8) {
    drv_HD_PP_command (allControllers, 0x30, T_INIT1); /* 8 Bit mode, wait 4.1 ms */
    drv_HD_PP_command (allControllers, 0x30, T_INIT2); /* 8 Bit mode, wait 100 us */
    drv_HD_PP_command (allControllers, 0x38, T_EXEC);  /* 8 Bit mode, 1/16 duty cycle, 5x8 font */
  } else {
    drv_HD_PP_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit mode, wait 4.1 ms */
    drv_HD_PP_nibble  (allControllers, 0x03); udelay(T_INIT2); /* 4 Bit mode, wait 100 us */
    drv_HD_PP_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit mode, wait 4.1 ms */
    drv_HD_PP_nibble  (allControllers, 0x02); udelay(T_INIT2); /* 4 Bit mode, wait 100 us */
    drv_HD_PP_command (allControllers, 0x28, T_EXEC);	       /* 4 Bit mode, 1/16 duty cycle, 5x8 font */
  }

  /* maybe use busy-flag from now on  */
  /* (we can't use the busy flag during the init sequence) */
  cfg_number(section, "UseBusy", 0, 0, 1, &UseBusy);
  
  /* make sure we don't use the busy flag with RW wired to GND */
  if (UseBusy && !SIGNAL_RW)   {
    error("%s: busy-flag checking is impossible with RW wired to GND!", Name);
    UseBusy=0;
  }

  /* make sure the display supports busy-flag checking in 4-Bit-Mode */
  /* at the moment this is inly possible with Martin Hejl's gpio driver, */
  /* which allows to use 4 bits as input and 4 bits as output */
  if (UseBusy && Bits==4 && !(Capabilities&CAP_BUSY4BIT)) {
    error("%s: Model '%s' does not support busy-flag checking in 4 bit mode", Name, Models[Model].name);
    UseBusy=0;
  }
  
  info("%s: %susing busy-flag checking", Name, UseBusy ? "" : "not ");

  /* The LCM-162 should really use BusyFlag checking */
  if (!UseBusy && (Capabilities & CAP_LCM162))   {
    error("%s: Model '%s' should definitely use busy-flag checking!", Name, Models[Model].name);
  }
  
  return 0;
}


static void drv_HD_PP_stop (void) 
{
  /* clear all signals */
  if (Bits==8) {
    drv_generic_parport_control (SIGNAL_RS|SIGNAL_RW|SIGNAL_ENABLE|SIGNAL_ENABLE2|SIGNAL_BACKLIGHT|SIGNAL_GPO, 0);
  } else {
    drv_generic_parport_data (0);
  }

  drv_generic_parport_close();
  
}



/****************************************/
/***  i2c dependant functions         ***/
/****************************************/

/* Fixme: remove the __attribute__((unused)) as soon as the i2c driver works */
static void drv_HD_I2C_nibble (const __attribute__((unused)) unsigned char controller, 
			       const __attribute__((unused)) unsigned char nibble)
{
/* Fixme: I2C support does not compile */
#if 0
  /* clear ENABLE */
  /* put data on DB1..DB4 */
  /* nibble already contains RS bit! */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble);
  
  /* Address set-up time */
  ndelay(T_AS);
  
  /* rise ENABLE */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble | SIGNAL_ENABLE);
  
  /* Enable pulse width */
  ndelay(T_PW);
  
  /* lower ENABLE */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble);
  
  /* Address hold time */
  ndelay(T_H);
#endif
}


static void drv_HD_I2C_byte (const unsigned char controller, const unsigned char data)
{
  /* send data with RS disabled */
  /* send high nibble of the data */
  drv_HD_I2C_nibble (controller, ((data>>4)&0x0f)|SIGNAL_RS);

  /* Make sure we honour T_CYCLE */
  ndelay(T_CYCLE-T_AS-T_PW);

  /* send low nibble of the data */
  drv_HD_I2C_nibble(controller, (data&0x0f)|SIGNAL_RS);
}


static void drv_HD_I2C_command (const unsigned char controller, const unsigned char cmd, const int delay)
{
  /* send data with RS disabled */
  drv_HD_I2C_byte (controller, cmd);
 
  /* wait for command completion */
  udelay(delay);
}

static void drv_HD_I2C_data (const unsigned char controller, const char *string, const int len, const int delay)
{
  int l = len;
 
  /* sanity check */
  if (len<=0) return;
 
  while (l--) {
    /* send data with RS enabled */
    drv_HD_I2C_byte (controller, *(string++));
     
    /* wait for command completion */
    udelay(delay);
  }
}


static int drv_HD_I2C_load (const char *section)
{
  int dev;
  char *bus,*device;

  bus    = cfg_get(section, "Port", NULL);   
  device = cfg_get(section, "Device", NULL);   
  dev    = 0x70;

  info("%s: initializing I2C bus %s",Name,bus);
  if ((i2c_device = open(bus,O_RDWR)) < 0) {
    error("%s: I2C bus %s open failed !\n",Name,bus);
    return -1;
  }
  
  info("%s: initializing I2C slave device 0x%x",Name,dev);
/* Fixme: I2C support does not compile */
#if 0
  if (ioctl(i2c_device,I2C_SLAVE, (dev>>1) ) < 0) {
    error("%s: error initializing device 0x%x\n",Name,dev);
    close(i2c_device);
    return -1;
  }
#endif

  info("%s: detecting I2C device 0x%x on bus %s ",Name,dev,bus);
/* Fixme: I2C support does not compile */
#if 0
  if (i2c_smbus_write_quick(i2c_device,I2C_SMBUS_WRITE) < 0) {
    error("%s: i2c slave-device 0x%x not found!\n",Name,dev);
    close(i2c_device);
    return -1;
  }
#endif
  
  if (cfg_number(section, "Bits", 8, 4, 8, &Bits)<0) return -1;
  if (Bits!=4) {
    error ("%s: bad %s.Bits '%d' from %s, should be '4' ", Name, section, Bits, cfg_source());
    return -1;
  }   
  
  info ("%s: using %d bit mode", Name, Bits);
  
  /* initialize *both* displays */
  drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit mode, wait 4.1 ms */
  drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT2); /* 4 Bit mode, wait 100 us */
  drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit mode, wait 4.1 ms */
  drv_HD_I2C_nibble  (allControllers, 0x02); udelay(T_INIT2); /* 4 Bit mode, wait 100 us */
  drv_HD_I2C_command (allControllers, 0x28, T_EXEC);          /* 4 Bit mode, 1/16 duty cycle, 5x8 font */

  info("%s: I2C initialization done", Name);

  return 0;
}


static void drv_HD_I2C_stop (void)
{
  /* clear all signals */
  // drv_generic_i2c_data (0);
  /* close port */
  // drv_generic_i2c_close();

  close(i2c_device);
}


/****************************************/
/***  display dependant functions     ***/
/****************************************/

static void drv_HD_clear (void)
{
  drv_HD_command (allControllers, 0x01, T_CLEAR); /* clear *both* displays */
}


static void drv_HD_goto (int row, int col)
{
  int pos;

  /* handle multiple displays/controllers */
  if (numControllers > 1 && row >= DROWS/2) {
    row -= DROWS/2;
    currController = 2;
  } else {
    currController = 1;
  }
   
  /* 16x1 Displays are organized as 8x2 :-( */
  if (DCOLS == 16 && DROWS == 1 && col > 7) {
    row++;
    col -= 8;
  }
  
  if (Capabilities & CAP_HD66712) {
    /* the HD66712 doesn't have a braindamadged RAM layout */
    pos = row*32 + col;
  } else {
    /* 16x4 Displays use a slightly different layout */
    if (DCOLS == 16 && DROWS == 4) {
      pos = (row%2)*64 + (row/2)*16 + col;
    } else {  
      pos = (row%2)*64 + (row/2)*20 + col;
    }
  }
  drv_HD_command (currController, (0x80|pos), T_EXEC);
}


static void drv_HD_write (const int row, const int col, const char *data, const int len)
{
  drv_HD_goto (row, col);
  drv_HD_data (currController, data, len, T_EXEC);
}


static void drv_HD_defchar (const int ascii, const unsigned char *matrix)
{
  int i;
  char buffer[8];

  for (i = 0; i < 8; i++) {
    buffer[i] = matrix[i] & 0x1f;
  }
  
  /* define chars on *both* controllers! */
  drv_HD_command (allControllers, 0x40|8*ascii, T_EXEC);
  drv_HD_data (allControllers, buffer, 8, T_WRCG);
}


static int drv_HD_backlight (int backlight)
{
  if (!(Capabilities & CAP_BACKLIGHT)) return -1;

  if (backlight < 0) backlight = 0;
  if (backlight > 1) backlight = 1;

  drv_generic_parport_control (SIGNAL_BACKLIGHT, backlight);

  return backlight;
}

  
static int drv_HD_brightness (int brightness)
{
  char cmd;
  
  if (!(Capabilities & CAP_BRIGHTNESS)) return -1;

  if (brightness<0) brightness=0;
  if (brightness>3) brightness=3;

  cmd='0'+brightness;
  
  drv_HD_command (allControllers, 0x38, T_EXEC); /* enable function */
  drv_HD_data (allControllers, &cmd, 1, T_WRCG); /* set brightness */

  return brightness;
}

  
/* Fixme: GPO's */
#if 0
static void drv_HD_setGPO (const int bits)
{
  if (Lcd.gpos>0) {
    
    /* put data on DB1..DB8 */
    drv_generic_parport_data (bits);
    
    /* 74HCT573 set-up time */
    ndelay(20);
    
    /* send data */
    /* 74HCT573 enable pulse width = 24ns */
    drv_generic_parport_toggle (SIGNAL_GPO, 1, 230);
  }
}
#endif


static void drv_HD_LCM162_timer (void __attribute__((unused)) *notused)
{
  static unsigned char data = 0x00;

  /* Bit 3+5 : key number */
  /* Bit 6   : key press/release */
  unsigned char mask3 = 1<<3;
  unsigned char mask5 = 1<<5;
  unsigned char mask6 = 1<<6;
  unsigned char mask  = mask3 | mask5 | mask6;

  int keynum;
  int updown;
  
  unsigned char temp;
  
  temp = drv_generic_parport_status() & mask;

  if (data != temp) {
    data = temp;

    keynum = (data & mask3 ? 1 : 0) + (data & mask5 ? 2 : 0);
    updown = (data & mask6 ? 1 : 0);

    debug ("key %d press %d", keynum, updown);
  }
}


static int drv_HD_start (const char *section, const int quiet)
{
  char *model, *size, *bus;
  int rows=-1, cols=-1, gpos=-1;
  
  model=cfg_get(section, "Model", "generic");
  if (model!=NULL && *model!='\0') {
    int i;
    for (i=0; Models[i].type!=0xff; i++) {
      if (strcasecmp(Models[i].name, model)==0) break;
    }
    if (Models[i].type==0xff) {
      error ("%s: %s.Model '%s' is unknown from %s", Name, section, model, cfg_source());
      return -1;
    }
    Model=i;
    Capabilities=Models[Model].capabilities;
    info ("%s: using model '%s'", Name, Models[Model].name);
  } else {
    error ("%s: empty '%s.Model' entry from %s", Name, section, cfg_source());
    if (model) free (model);
    return -1;
  }
  free (model);

  bus=cfg_get(section, "Bus", "parport");
  if (bus==NULL && *bus=='\0') {
    error ("%s: empty '%s.Bus' entry from %s", Name, section, cfg_source());
    if (bus) free (bus);
    return -1;
  }

  if (strcasecmp(bus, "parport") == 0) {
    info ("%s: using parallel port", Name);
    Bus = BUS_PP;
    drv_HD_load    = drv_HD_PP_load;
    drv_HD_command = drv_HD_PP_command;
    drv_HD_data    = drv_HD_PP_data;
    drv_HD_stop    = drv_HD_PP_stop;
    
  } else if (strcasecmp(bus, "i2c") == 0) {
    info ("%s: using I2C bus", Name);
    Bus = BUS_I2C;
    drv_HD_load    = drv_HD_I2C_load;
    drv_HD_command = drv_HD_I2C_command;
    drv_HD_data    = drv_HD_I2C_data;
    drv_HD_stop    = drv_HD_I2C_stop;

  } else {
    error ("%s: bad %s.Bus '%s' from %s, should be 'parport' or 'i2c'", Name, section, bus, cfg_source());
    free (bus);
    return -1;
  }

  /* sanity check: Model can use bus */
  if (!(Capabilities & Bus)) {
    error ("%s: Model '%s' cannot be used on the %s bus!", Name, Models[Model].name, bus);
    free (bus);
    return -1;
  }
  free(bus);
  
  size=cfg_get(section, "Size", NULL);
  if (size==NULL || *size=='\0') {
    error ("%s: no '%s.Size' entry from %s", Name, section, cfg_source());
    free(size);
    return -1;
  }
  if (sscanf(size,"%dx%d",&cols,&rows)!=2 || rows<1 || cols<1) {
    error ("%s: bad %s.Size '%s' from %s", Name, section, size, cfg_source());
    free(size);
    return -1;
  }
  free(size);
  DROWS = rows;
  DCOLS = cols;
  
  if (cfg_number(section, "Controllers", 1, 1, 2, &numControllers)<0) return -1;
  info ("%s: using %d controller(s)", Name, numControllers);
  
  /* current controller */
  currController=1;
  
  /* Bitmask for *all* Controllers */
  allControllers = numControllers==2 ? 3 : 1;
  
  if (cfg_number(section, "GPOs", 0, 0, 8, &gpos)<0) return -1;
  if (gpos > 0 && !(Capabilities & CAP_GPO)) {
    error ("%s: Model '%s' does not support GPO's!", Name, Models[Model].name);
    gpos = 0;
  }
  GPOS  = gpos;
  if (gpos > 0) {
    info ("%s: using %d GPO's", Name, GPOS);
  }
  
  if (drv_HD_load(section) < 0) {
    error ("%s: start display failed!", Name);
    return -1;
  }
  
  drv_HD_command (allControllers, 0x08, T_EXEC);  /* Display off, cursor off, blink off */
  drv_HD_command (allControllers, 0x0c, T_CLEAR); /* Display on, cursor off, blink off, wait 1.64 ms */
  drv_HD_command (allControllers, 0x06, T_EXEC);  /* curser moves to right, no shift */

  if ((Capabilities & CAP_HD66712) && DROWS > 2) {
    drv_HD_command (allControllers, Bits==8?0x3c:0x2c, T_EXEC); /* set extended register enable bit */
    drv_HD_command (allControllers, 0x09,              T_EXEC); /* set 4-line mode */
    drv_HD_command (allControllers, Bits==8?0x38:0x28, T_EXEC); /* clear extended register enable bit */
  }

  drv_HD_clear(); /* clear *both* displays */
  drv_HD_command (allControllers, 0x03, T_CLEAR); /* return home */
  
  /* maybe set backlight */
  if (Capabilities & CAP_BACKLIGHT) {
    int backlight;
    if (cfg_number(section, "Backlight", 0, 0, 1, &backlight) > 0) {
      info ("%s: backlight %s", Name, backlight ? "enabled" : "disabled");
      drv_HD_backlight(backlight);
    }
  }

  /* maybe set brightness */
  if (Capabilities & CAP_BRIGHTNESS) {
    int brightness;
    if (cfg_number(section, "Brightness", 0, 0, 3, &brightness) > 0) {
      info ("%s: brightness level %d", Name, brightness);
      drv_HD_brightness(brightness);
    }
  }

  /* install keypad polling timer for LCM-162 */
  if (Capabilities & CAP_LCM162) {
    timer_add (drv_HD_LCM162_timer, NULL, 10, 0);
  }
  
  if (!quiet) {
    char buffer[40];
    qprintf(buffer, sizeof(buffer), "%s %dx%d", Name, DCOLS, DROWS);
    if (drv_generic_text_greet (buffer, NULL)) {
      sleep (3);
      drv_HD_clear();
    }
  }
    
  return 0;
}


/****************************************/
/***            plugins               ***/
/****************************************/


static void plugin_backlight (RESULT *result, RESULT *arg1)
{
  double backlight;
  
  backlight = drv_HD_backlight(R2N(arg1));
  SetResult(&result, R_NUMBER, &backlight); 
}


static void plugin_brightness (RESULT *result, RESULT *arg1)
{
  double brightness;
  
  brightness = drv_HD_brightness(R2N(arg1));
  SetResult(&result, R_NUMBER, &brightness); 
}


/****************************************/
/***        widget callbacks          ***/
/****************************************/


/* using drv_generic_text_draw(W) */
/* using drv_generic_text_icon_draw(W) */
/* using drv_generic_text_bar_draw(W) */


/****************************************/
/***        exported functions        ***/
/****************************************/


/* list models */
int drv_HD_list (void)
{
  int i;
  
  for (i=0; Models[i].type!=0xff; i++) {
    printf ("%s ", Models[i].name);
  }
  return 0;
}


/* initialize driver & display */
int drv_HD_init (const char *section, const int quiet)
{
  WIDGET_CLASS wc;
  int asc255bug;
  int ret;  
  
  /* display preferences */
  XRES  = 5;      /* pixel width of one char  */
  YRES  = 8;      /* pixel height of one char  */
  CHARS = 8;      /* number of user-defineable characters */
  CHAR0 = 0;      /* ASCII of first user-defineable char */
  GOTO_COST = 1;  /* number of bytes a goto command requires */
  
  /* real worker functions */
  drv_generic_text_real_write   = drv_HD_write;
  drv_generic_text_real_defchar = drv_HD_defchar;


  /* start display */
  if ((ret=drv_HD_start (section, quiet))!=0)
    return ret;
  
  /* initialize generic text driver */
  if ((ret=drv_generic_text_init(section, Name))!=0)
    return ret;

  /* initialize generic icon driver */
  if ((ret=drv_generic_text_icon_init())!=0)
    return ret;
  
  /* initialize generic bar driver */
  if ((ret=drv_generic_text_bar_init(0))!=0)
    return ret;
  
  /* add fixed chars to the bar driver */
  /* most displays have a full block on ascii 255, but some have kind of  */
  /* an 'inverted P'. If you specify 'asc255bug 1 in the config, this */
  /* char will not be used, but rendered by the bar driver */
  cfg_number(section, "asc255bug", 0, 0, 1, &asc255bug);
  drv_generic_text_bar_add_segment (  0,  0,255, 32); /* ASCII  32 = blank */
  if (!asc255bug) 
    drv_generic_text_bar_add_segment (255,255,255,255); /* ASCII 255 = block */
  
  /* register text widget */
  wc=Widget_Text;
  wc.draw=drv_generic_text_draw;
  widget_register(&wc);
  
  /* register icon widget */
  wc=Widget_Icon;
  wc.draw=drv_generic_text_icon_draw;
  widget_register(&wc);
  
  /* register bar widget */
  wc=Widget_Bar;
  wc.draw=drv_generic_text_bar_draw;
  widget_register(&wc);
  
  /* register plugins */
  if (Capabilities & CAP_BACKLIGHT) {
    AddFunction ("LCD::backlight", 1, plugin_backlight);
  }
  if (Capabilities & CAP_BRIGHTNESS) {
    AddFunction ("LCD::brightness", 1, plugin_brightness);
  }
  
  return 0;
}


/* close driver & display */
int drv_HD_quit (const int quiet) {

  info("%s: shutting down.", Name);

  drv_generic_text_quit();

  /* clear *both* displays */
  drv_HD_clear();
  
  /* say goodbye... */
  if (!quiet) {
    drv_generic_text_greet ("goodbye!", NULL);
  }
  
  drv_HD_stop();
  
  return (0);
}


DRIVER drv_HD44780 = {
  name: Name,
  list: drv_HD_list,
  init: drv_HD_init,
  quit: drv_HD_quit, 
};