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
30static unsigned int ks0108_port = CONFIG_KS0108_PORT;
31module_param(ks0108_port, uint, S_IRUGO);
32MODULE_PARM_DESC(ks0108_port, "Parallel port where the LCD is connected");
33
34static unsigned int ks0108_delay = CONFIG_KS0108_DELAY;
35module_param(ks0108_delay, uint, S_IRUGO);
36MODULE_PARM_DESC(ks0108_delay, "Delay between each control writing (microseconds)");
37
38/*
39 * Device
40 */
41
42static struct parport *ks0108_parport;
43static 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
63void ks0108_writedata(unsigned char byte)
64{
65	parport_write_data(ks0108_parport, byte);
66}
67
68void 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
74void 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
79void ks0108_startline(unsigned char startline)
80{
81	ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) |
82			 bit(7));
83}
84
85void ks0108_address(unsigned char address)
86{
87	ks0108_writedata(min_t(unsigned char, address, 63) | bit(6));
88}
89
90void 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
96EXPORT_SYMBOL_GPL(ks0108_writedata);
97EXPORT_SYMBOL_GPL(ks0108_writecontrol);
98EXPORT_SYMBOL_GPL(ks0108_displaystate);
99EXPORT_SYMBOL_GPL(ks0108_startline);
100EXPORT_SYMBOL_GPL(ks0108_address);
101EXPORT_SYMBOL_GPL(ks0108_page);
102
103/*
104 * Is the module inited?
105 */
106
107static unsigned char ks0108_inited;
108unsigned char ks0108_isinited(void)
109{
110	return ks0108_inited;
111}
112EXPORT_SYMBOL_GPL(ks0108_isinited);
113
114static 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
139err_unreg_device:
140	parport_unregister_device(ks0108_pardevice);
141	ks0108_pardevice = NULL;
142}
143
144static 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
164static 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
171static int __init ks0108_init(void)
172{
173	return parport_register_driver(&ks0108_parport_driver);
174}
175
176static void __exit ks0108_exit(void)
177{
178	parport_unregister_driver(&ks0108_parport_driver);
179}
180
181module_init(ks0108_init);
182module_exit(ks0108_exit);
183
184MODULE_LICENSE("GPL v2");
185MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
186MODULE_DESCRIPTION("ks0108 LCD Controller driver");
187
188