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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 
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 
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 }
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,
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 <[email protected]>");
177 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
178