xref: /openbmc/linux/drivers/auxdisplay/ks0108.c (revision c9efdbe6)
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 /*
129  * Module Init & Exit
130  */
131 
132 static int __init ks0108_init(void)
133 {
134 	int result;
135 	int ret = -EINVAL;
136 
137 	ks0108_parport = parport_find_base(ks0108_port);
138 	if (ks0108_parport == NULL) {
139 		pr_err("ERROR: parport didn't find %i port\n", ks0108_port);
140 		goto none;
141 	}
142 
143 	ks0108_pardevice = parport_register_device(ks0108_parport, KS0108_NAME,
144 		NULL, NULL, NULL, PARPORT_DEV_EXCL, NULL);
145 	parport_put_port(ks0108_parport);
146 	if (ks0108_pardevice == NULL) {
147 		pr_err("ERROR: parport didn't register new device\n");
148 		goto none;
149 	}
150 
151 	result = parport_claim(ks0108_pardevice);
152 	if (result != 0) {
153 		pr_err("ERROR: can't claim %i parport, maybe in use\n",
154 		       ks0108_port);
155 		ret = result;
156 		goto registered;
157 	}
158 
159 	ks0108_inited = 1;
160 	return 0;
161 
162 registered:
163 	parport_unregister_device(ks0108_pardevice);
164 
165 none:
166 	return ret;
167 }
168 
169 static void __exit ks0108_exit(void)
170 {
171 	parport_release(ks0108_pardevice);
172 	parport_unregister_device(ks0108_pardevice);
173 }
174 
175 module_init(ks0108_init);
176 module_exit(ks0108_exit);
177 
178 MODULE_LICENSE("GPL v2");
179 MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
180 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
181 
182