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
   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28 #include <linux/init.h>
  29 #include <linux/module.h>
  30 #include <linux/kernel.h>
  31 #include <linux/delay.h>
  32 #include <linux/fs.h>
  33 #include <linux/io.h>
  34 #include <linux/parport.h>
  35 #include <linux/uaccess.h>
  36 #include <linux/ks0108.h>
  37
  38 #define KS0108_NAME "ks0108"
  39
  40 /*
  41  * Module Parameters
  42  */
  43
  44 static unsigned int ks0108_port = CONFIG_KS0108_PORT;
  45 module_param(ks0108_port, uint, S_IRUGO);
  46 MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
  47
  48 static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
  49 module_param(ks0108_delay, uint, S_IRUGO);
  50 MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
  51
  52 /*
  53  * Device
  54  */
  55
  56 static struct parport *ks0108_parport;
  57 static struct pardevice *ks0108_pardevice;
  58
  59 /*
  60  * ks0108 Exported Commands (don't lock)
  61  *
  62  *   You _should_ lock in the top driver: This functions _should not_
  63  *   get race conditions in any way. Locking for each byte here would be
  64  *   so slow and useless.
  65  *
  66  *   There are not bit definitions because they are not flags,
  67  *   just arbitrary combinations defined by the documentation for each
  68  *   function in the ks0108 LCD controller. If you want to know what means
  69  *   a specific combination, look at the function's name.
  70  *
  71  *   The ks0108_writecontrol bits need to be reverted ^(0,1,3) because
  72  *   the parallel port also revert them using a "not" logic gate.
  73  */
  74
  75 #define bit(n) (((unsigned char)1)<<(n))
  76
  77 void ks0108_writedata(unsigned char byte)
  78 {
  79         parport_write_data(ks0108_parport, byte);
  80 }
  81
  82 void ks0108_writecontrol(unsigned char byte)
  83 {
  84         udelay(ks0108_delay);
  85         parport_write_control(ks0108_parport, byte ^ (bit(0) | bit(1) | bit(3)));
  86 }
  87
  88 void ks0108_displaystate(unsigned char state)
  89 {
  90         ks0108_writedata((state ? bit(0) : 0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5));
  91 }
  92
  93 void ks0108_startline(unsigned char startline)
  94 {
  95         ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) |
  96                          bit(7));
  97 }
  98
  99 void ks0108_address(unsigned char address)
 100 {
 101         ks0108_writedata(min_t(unsigned char, address, 63) | bit(6));
 102 }
 103
 104 void ks0108_page(unsigned char page)
 105 {
 106         ks0108_writedata(min_t(unsigned char, page, 7) | bit(3) | bit(4) |
 107                          bit(5) | bit(7));
 108 }
 109
 110 EXPORT_SYMBOL_GPL(ks0108_writedata);
 111 EXPORT_SYMBOL_GPL(ks0108_writecontrol);
 112 EXPORT_SYMBOL_GPL(ks0108_displaystate);
 113 EXPORT_SYMBOL_GPL(ks0108_startline);
 114 EXPORT_SYMBOL_GPL(ks0108_address);
 115 EXPORT_SYMBOL_GPL(ks0108_page);
 116
 117 /*
 118  * Is the module inited?
 119  */
 120
 121 static unsigned char ks0108_inited;
 122 unsigned char ks0108_isinited(void)
 123 {
 124         return ks0108_inited;
 125 }
 126 EXPORT_SYMBOL_GPL(ks0108_isinited);
 127
 128 static void ks0108_parport_attach(struct parport *port)
 129 {
 130         struct pardev_cb ks0108_cb;
 131
 132         if (port->base != ks0108_port)
 133                 return;
 134
 135         memset(&ks0108_cb, 0, sizeof(ks0108_cb));
 136         ks0108_cb.flags = PARPORT_DEV_EXCL;
 137         ks0108_pardevice = parport_register_dev_model(port, KS0108_NAME,
 138                                                       &ks0108_cb, 0);
 139         if (!ks0108_pardevice) {
 140                 pr_err("ERROR: parport didn't register new device\n");
 141                 return;
 142         }
 143         if (parport_claim(ks0108_pardevice)) {
 144                 pr_err("could not claim access to parport %i. Aborting.\n",
 145                        ks0108_port);
 146                 goto err_unreg_device;
 147         }
 148
 149         ks0108_parport = port;
 150         ks0108_inited = 1;
 151         return;
 152
 153 err_unreg_device:
 154         parport_unregister_device(ks0108_pardevice);
 155         ks0108_pardevice = NULL;
 156 }
 157
 158 static void ks0108_parport_detach(struct parport *port)
 159 {
 160         if (port->base != ks0108_port)
 161                 return;
 162
 163         if (!ks0108_pardevice) {
 164                 pr_err("%s: already unregistered.\n", KS0108_NAME);
 165                 return;
 166         }
 167
 168         parport_release(ks0108_pardevice);
 169         parport_unregister_device(ks0108_pardevice);
 170         ks0108_pardevice = NULL;
 171         ks0108_parport = NULL;
 172 }
 173
 174 /*
 175  * Module Init & Exit
 176  */
 177
 178 static struct parport_driver ks0108_parport_driver = {
 179         .name = "ks0108",
 180         .match_port = ks0108_parport_attach,
 181         .detach = ks0108_parport_detach,
 182         .devmodel = true,
 183 };
 184
 185 static int __init ks0108_init(void)
 186 {
 187         return parport_register_driver(&ks0108_parport_driver);
 188 }
 189
 190 static void __exit ks0108_exit(void)
 191 {
 192         parport_unregister_driver(&ks0108_parport_driver);
 193 }
 194
 195 module_init(ks0108_init);
 196 module_exit(ks0108_exit);
 197
 198 MODULE_LICENSE("GPL v2");
 199 MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
 200 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
 201