drivers/auxdisplay/ks0108.c

   1 /*
   2  *    Filename: ks0108.c
   3  *     Version: 0.1.0
   4  * Description: ks0108 LCD Controller driver
   5  *     License: GPLv2
   6  *     Depends: parport
   7  *
   8  *      Author: Copyright (C) Miguel Ojeda Sandonis <maxextreme@gmail.com>
   9  *        Date: 2006-10-31
  10  *
  11  *  This program is free software; you can redistribute it and/or modify
  12  *  it under the terms of the GNU General Public License version 2 as
  13  *  published by the Free Software Foundation.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License
  21  *  along with this program; if not, write to the Free Software
  22  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  *
  24  */
  25
  26 #include <linux/init.h>
  27 #include <linux/module.h>
  28 #include <linux/kernel.h>
  29 #include <linux/delay.h>
  30 #include <linux/fs.h>
  31 #include <linux/io.h>
  32 #include <linux/parport.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/ks0108.h>
  35
  36 #define KS0108_NAME "ks0108"
  37
  38 /*
  39  * Module Parameters
  40  */
  41
  42 static unsigned int ks0108_port = CONFIG_KS0108_PORT;
  43 module_param(ks0108_port, uint, S_IRUGO);
  44 MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
  45
  46 static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
  47 module_param(ks0108_delay, uint, S_IRUGO);
  48 MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
  49
  50 /*
  51  * Device
  52  */
  53
  54 static struct parport *ks0108_parport;
  55 static struct pardevice *ks0108_pardevice;
  56
  57 /*
  58  * ks0108 Exported Commands (don't lock)
  59  *
  60  *   You _should_ lock in the top driver: This functions _should not_
  61  *   get race conditions in any way. Locking for each byte here would be
  62  *   so slow and useless.
  63  *
  64  *   There are not bit definitions because they are not flags,
  65  *   just arbitrary combinations defined by the documentation for each
  66  *   function in the ks0108 LCD controller. If you want to know what means
  67  *   a specific combination, look at the function's name.
  68  *
  69  *   The ks0108_writecontrol bits need to be reverted ^(0,1,3) because
  70  *   the parallel port also revert them using a "not" logic gate.
  71  */
  72
  73 #define bit(n) (((unsigned char)1)<<(n))
  74
  75 void ks0108_writedata(unsigned char byte)
  76 {
  77         parport_write_data(ks0108_parport, byte);
  78 }
  79
  80 void ks0108_writecontrol(unsigned char byte)
  81 {
  82         udelay(ks0108_delay);
  83         parport_write_control(ks0108_parport, byte ^ (bit(0) | bit(1) | bit(3)));
  84 }
  85
  86 void ks0108_displaystate(unsigned char state)
  87 {
  88         ks0108_writedata((state ? bit(0) : 0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5));
  89 }
  90
  91 void ks0108_startline(unsigned char startline)
  92 {
  93         ks0108_writedata(min(startline,(unsigned char)63) | bit(6) | bit(7));
  94 }
  95
  96 void ks0108_address(unsigned char address)
  97 {
  98         ks0108_writedata(min(address,(unsigned char)63) | bit(6));
  99 }
 100
 101 void ks0108_page(unsigned char page)
 102 {
 103         ks0108_writedata(min(page,(unsigned char)7) | bit(3) | bit(4) | bit(5) | bit(7));
 104 }
 105
 106 EXPORT_SYMBOL_GPL(ks0108_writedata);
 107 EXPORT_SYMBOL_GPL(ks0108_writecontrol);
 108 EXPORT_SYMBOL_GPL(ks0108_displaystate);
 109 EXPORT_SYMBOL_GPL(ks0108_startline);
 110 EXPORT_SYMBOL_GPL(ks0108_address);
 111 EXPORT_SYMBOL_GPL(ks0108_page);
 112
 113 /*
 114  * Is the module inited?
 115  */
 116
 117 static unsigned char ks0108_inited;
 118 unsigned char ks0108_isinited(void)
 119 {
 120         return ks0108_inited;
 121 }
 122 EXPORT_SYMBOL_GPL(ks0108_isinited);
 123
 124 /*
 125  * Module Init & Exit
 126  */
 127
 128 static int __init ks0108_init(void)
 129 {
 130         int result;
 131         int ret = -EINVAL;
 132
 133         ks0108_parport = parport_find_base(ks0108_port);
 134         if (ks0108_parport == NULL) {
 135                 printk(KERN_ERR KS0108_NAME ": ERROR: "
 136                         "parport didn't find %i port\n", ks0108_port);
 137                 goto none;
 138         }
 139
 140         ks0108_pardevice = parport_register_device(ks0108_parport, KS0108_NAME,
 141                 NULL, NULL, NULL, PARPORT_DEV_EXCL, NULL);
 142         if (ks0108_pardevice == NULL) {
 143                 printk(KERN_ERR KS0108_NAME ": ERROR: "
 144                         "parport didn't register new device\n");
 145                 goto none;
 146         }
 147
 148         result = parport_claim(ks0108_pardevice);
 149         if (result != 0) {
 150                 printk(KERN_ERR KS0108_NAME ": ERROR: "
 151                         "can't claim %i parport, maybe in use\n", ks0108_port);
 152                 ret = result;
 153                 goto registered;
 154         }
 155
 156         ks0108_inited = 1;
 157         return 0;
 158
 159 registered:
 160         parport_unregister_device(ks0108_pardevice);
 161
 162 none:
 163         return ret;
 164 }
 165
 166 static void __exit ks0108_exit(void)
 167 {
 168         parport_release(ks0108_pardevice);
 169         parport_unregister_device(ks0108_pardevice);
 170 }
 171
 172 module_init(ks0108_init);
 173 module_exit(ks0108_exit);
 174
 175 MODULE_LICENSE("GPL v2");
 176 MODULE_AUTHOR("Miguel Ojeda Sandonis <maxextreme@gmail.com>");
 177 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
 178