linux/drivers/auxdisplay/ks0108.c
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   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
   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
  42static unsigned int ks0108_port = CONFIG_KS0108_PORT;
  43module_param(ks0108_port, uint, S_IRUGO);
  44MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
  45
  46static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
  47module_param(ks0108_delay, uint, S_IRUGO);
  48MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
  49
  50/*
  51 * Device
  52 */
  53
  54static struct parport *ks0108_parport;
  55static 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
  75void ks0108_writedata(unsigned char byte)
  76{
  77        parport_write_data(ks0108_parport, byte);
  78}
  79
  80void 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
  86void 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
  91void ks0108_startline(unsigned char startline)
  92{
  93        ks0108_writedata(min(startline,(unsigned char)63) | bit(6) | bit(7));
  94}
  95
  96void ks0108_address(unsigned char address)
  97{
  98        ks0108_writedata(min(address,(unsigned char)63) | bit(6));
  99}
 100
 101void ks0108_page(unsigned char page)
 102{
 103        ks0108_writedata(min(page,(unsigned char)7) | bit(3) | bit(4) | bit(5) | bit(7));
 104}
 105
 106EXPORT_SYMBOL_GPL(ks0108_writedata);
 107EXPORT_SYMBOL_GPL(ks0108_writecontrol);
 108EXPORT_SYMBOL_GPL(ks0108_displaystate);
 109EXPORT_SYMBOL_GPL(ks0108_startline);
 110EXPORT_SYMBOL_GPL(ks0108_address);
 111EXPORT_SYMBOL_GPL(ks0108_page);
 112
 113/*
 114 * Is the module inited?
 115 */
 116
 117static unsigned char ks0108_inited;
 118unsigned char ks0108_isinited(void)
 119{
 120        return ks0108_inited;
 121}
 122EXPORT_SYMBOL_GPL(ks0108_isinited);
 123
 124/*
 125 * Module Init & Exit
 126 */
 127
 128static 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
 159registered:
 160        parport_unregister_device(ks0108_pardevice);
 161
 162none:
 163        return ret;
 164}
 165
 166static void __exit ks0108_exit(void)
 167{
 168        parport_release(ks0108_pardevice);
 169        parport_unregister_device(ks0108_pardevice);
 170}
 171
 172module_init(ks0108_init);
 173module_exit(ks0108_exit);
 174
 175MODULE_LICENSE("GPL v2");
 176MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
 177MODULE_DESCRIPTION("ks0108 LCD Controller driver");
 178
 179
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