1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Filename: ks0108.c
4 * Version: 0.1.0
5 * Description: ks0108 LCD Controller driver
6 * Depends: parport
7 *
8 * Author: Copyright (C) Miguel Ojeda Sandonis
9 * Date: 2006-10-31
10 */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/kernel.h>
17 #include <linux/delay.h>
18 #include <linux/fs.h>
19 #include <linux/io.h>
20 #include <linux/parport.h>
21 #include <linux/uaccess.h>
22 #include <linux/ks0108.h>
23
24 #define KS0108_NAME "ks0108"
25
26 /*
27 * Module Parameters
28 */
29
30 static unsigned int ks0108_port = CONFIG_KS0108_PORT;
31 module_param(ks0108_port, uint, S_IRUGO);
32 MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
33
34 static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
35 module_param(ks0108_delay, uint, S_IRUGO);
36 MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
37
38 /*
39 * Device
40 */
41
42 static struct parport *ks0108_parport;
43 static struct pardevice *ks0108_pardevice;
44
45 /*
46 * ks0108 Exported Commands (don't lock)
47 *
48 * You _should_ lock in the top driver: This functions _should not_
49 * get race conditions in any way. Locking for each byte here would be
50 * so slow and useless.
51 *
52 * There are not bit definitions because they are not flags,
53 * just arbitrary combinations defined by the documentation for each
54 * function in the ks0108 LCD controller. If you want to know what means
55 * a specific combination, look at the function's name.
56 *
57 * The ks0108_writecontrol bits need to be reverted ^(0,1,3) because
58 * the parallel port also revert them using a "not" logic gate.
59 */
60
61 #define bit(n) (((unsigned char)1)<<(n))
62
ks0108_writedata(unsigned char byte)63 void ks0108_writedata(unsigned char byte)
64 {
65 parport_write_data(ks0108_parport, byte);
66 }
67
ks0108_writecontrol(unsigned char byte)68 void ks0108_writecontrol(unsigned char byte)
69 {
70 udelay(ks0108_delay);
71 parport_write_control(ks0108_parport, byte ^ (bit(0) | bit(1) | bit(3)));
72 }
73
ks0108_displaystate(unsigned char state)74 void ks0108_displaystate(unsigned char state)
75 {
76 ks0108_writedata((state ? bit(0) : 0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5));
77 }
78
ks0108_startline(unsigned char startline)79 void ks0108_startline(unsigned char startline)
80 {
81 ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) |
82 bit(7));
83 }
84
ks0108_address(unsigned char address)85 void ks0108_address(unsigned char address)
86 {
87 ks0108_writedata(min_t(unsigned char, address, 63) | bit(6));
88 }
89
ks0108_page(unsigned char page)90 void ks0108_page(unsigned char page)
91 {
92 ks0108_writedata(min_t(unsigned char, page, 7) | bit(3) | bit(4) |
93 bit(5) | bit(7));
94 }
95
96 EXPORT_SYMBOL_GPL(ks0108_writedata);
97 EXPORT_SYMBOL_GPL(ks0108_writecontrol);
98 EXPORT_SYMBOL_GPL(ks0108_displaystate);
99 EXPORT_SYMBOL_GPL(ks0108_startline);
100 EXPORT_SYMBOL_GPL(ks0108_address);
101 EXPORT_SYMBOL_GPL(ks0108_page);
102
103 /*
104 * Is the module inited?
105 */
106
107 static unsigned char ks0108_inited;
ks0108_isinited(void)108 unsigned char ks0108_isinited(void)
109 {
110 return ks0108_inited;
111 }
112 EXPORT_SYMBOL_GPL(ks0108_isinited);
113
ks0108_parport_attach(struct parport * port)114 static void ks0108_parport_attach(struct parport *port)
115 {
116 struct pardev_cb ks0108_cb;
117
118 if (port->base != ks0108_port)
119 return;
120
121 memset(&ks0108_cb, 0, sizeof(ks0108_cb));
122 ks0108_cb.flags = PARPORT_DEV_EXCL;
123 ks0108_pardevice = parport_register_dev_model(port, KS0108_NAME,
124 &ks0108_cb, 0);
125 if (!ks0108_pardevice) {
126 pr_err("ERROR: parport didn't register new device\n");
127 return;
128 }
129 if (parport_claim(ks0108_pardevice)) {
130 pr_err("could not claim access to parport %i. Aborting.\n",
131 ks0108_port);
132 goto err_unreg_device;
133 }
134
135 ks0108_parport = port;
136 ks0108_inited = 1;
137 return;
138
139 err_unreg_device:
140 parport_unregister_device(ks0108_pardevice);
141 ks0108_pardevice = NULL;
142 }
143
ks0108_parport_detach(struct parport * port)144 static void ks0108_parport_detach(struct parport *port)
145 {
146 if (port->base != ks0108_port)
147 return;
148
149 if (!ks0108_pardevice) {
150 pr_err("%s: already unregistered.\n", KS0108_NAME);
151 return;
152 }
153
154 parport_release(ks0108_pardevice);
155 parport_unregister_device(ks0108_pardevice);
156 ks0108_pardevice = NULL;
157 ks0108_parport = NULL;
158 }
159
160 /*
161 * Module Init & Exit
162 */
163
164 static struct parport_driver ks0108_parport_driver = {
165 .name = "ks0108",
166 .match_port = ks0108_parport_attach,
167 .detach = ks0108_parport_detach,
168 .devmodel = true,
169 };
170
ks0108_init(void)171 static int __init ks0108_init(void)
172 {
173 return parport_register_driver(&ks0108_parport_driver);
174 }
175
ks0108_exit(void)176 static void __exit ks0108_exit(void)
177 {
178 parport_unregister_driver(&ks0108_parport_driver);
179 }
180
181 module_init(ks0108_init);
182 module_exit(ks0108_exit);
183
184 MODULE_LICENSE("GPL v2");
185 MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
186 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
187
188