xref: /openbmc/linux/drivers/auxdisplay/ks0108.c (revision 2bdd5238)
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 <ojeda@kernel.org>
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, 0444);
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, 0444);
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 
63 void ks0108_writedata(unsigned char byte)
64 {
65 	parport_write_data(ks0108_parport, byte);
66 }
67 
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 
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 
79 void ks0108_startline(unsigned char startline)
80 {
81 	ks0108_writedata(min_t(unsigned char, startline, 63) | bit(6) |
82 			 bit(7));
83 }
84 
85 void ks0108_address(unsigned char address)
86 {
87 	ks0108_writedata(min_t(unsigned char, address, 63) | bit(6));
88 }
89 
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;
108 unsigned char ks0108_isinited(void)
109 {
110 	return ks0108_inited;
111 }
112 EXPORT_SYMBOL_GPL(ks0108_isinited);
113 
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 
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 module_parport_driver(ks0108_parport_driver);
171 
172 MODULE_LICENSE("GPL v2");
173 MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
174 MODULE_DESCRIPTION("ks0108 LCD Controller driver");
175 
176