1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Filename: cfag12864b.c
4 * Version: 0.1.0
5 * Description: cfag12864b LCD driver
6 * Depends: ks0108
7 *
8 * Author: Copyright (C) Miguel Ojeda <ojeda@kernel.org>
9 * Date: 2006-10-31
10 */
11
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/kernel.h>
15#include <linux/fs.h>
16#include <linux/slab.h>
17#include <linux/cdev.h>
18#include <linux/delay.h>
19#include <linux/device.h>
20#include <linux/jiffies.h>
21#include <linux/mutex.h>
22#include <linux/uaccess.h>
23#include <linux/vmalloc.h>
24#include <linux/workqueue.h>
25#include <linux/ks0108.h>
26#include <linux/cfag12864b.h>
27
28
29#define CFAG12864B_NAME "cfag12864b"
30
31/*
32 * Module Parameters
33 */
34
35static unsigned int cfag12864b_rate = CONFIG_CFAG12864B_RATE;
36module_param(cfag12864b_rate, uint, 0444);
37MODULE_PARM_DESC(cfag12864b_rate,
38 "Refresh rate (hertz)");
39
40/*
41 * cfag12864b Commands
42 *
43 * E = Enable signal
44 * Every time E switch from low to high,
45 * cfag12864b/ks0108 reads the command/data.
46 *
47 * CS1 = First ks0108controller.
48 * If high, the first ks0108 controller receives commands/data.
49 *
50 * CS2 = Second ks0108 controller
51 * If high, the second ks0108 controller receives commands/data.
52 *
53 * DI = Data/Instruction
54 * If low, cfag12864b will expect commands.
55 * If high, cfag12864b will expect data.
56 *
57 */
58
59#define bit(n) (((unsigned char)1)<<(n))
60
61#define CFAG12864B_BIT_E (0)
62#define CFAG12864B_BIT_CS1 (2)
63#define CFAG12864B_BIT_CS2 (1)
64#define CFAG12864B_BIT_DI (3)
65
66static unsigned char cfag12864b_state;
67
68static void cfag12864b_set(void)
69{
70 ks0108_writecontrol(byte: cfag12864b_state);
71}
72
73static void cfag12864b_setbit(unsigned char state, unsigned char n)
74{
75 if (state)
76 cfag12864b_state |= bit(n);
77 else
78 cfag12864b_state &= ~bit(n);
79}
80
81static void cfag12864b_e(unsigned char state)
82{
83 cfag12864b_setbit(state, CFAG12864B_BIT_E);
84 cfag12864b_set();
85}
86
87static void cfag12864b_cs1(unsigned char state)
88{
89 cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
90}
91
92static void cfag12864b_cs2(unsigned char state)
93{
94 cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
95}
96
97static void cfag12864b_di(unsigned char state)
98{
99 cfag12864b_setbit(state, CFAG12864B_BIT_DI);
100}
101
102static void cfag12864b_setcontrollers(unsigned char first,
103 unsigned char second)
104{
105 if (first)
106 cfag12864b_cs1(state: 0);
107 else
108 cfag12864b_cs1(state: 1);
109
110 if (second)
111 cfag12864b_cs2(state: 0);
112 else
113 cfag12864b_cs2(state: 1);
114}
115
116static void cfag12864b_controller(unsigned char which)
117{
118 if (which == 0)
119 cfag12864b_setcontrollers(first: 1, second: 0);
120 else if (which == 1)
121 cfag12864b_setcontrollers(first: 0, second: 1);
122}
123
124static void cfag12864b_displaystate(unsigned char state)
125{
126 cfag12864b_di(state: 0);
127 cfag12864b_e(state: 1);
128 ks0108_displaystate(state);
129 cfag12864b_e(state: 0);
130}
131
132static void cfag12864b_address(unsigned char address)
133{
134 cfag12864b_di(state: 0);
135 cfag12864b_e(state: 1);
136 ks0108_address(address);
137 cfag12864b_e(state: 0);
138}
139
140static void cfag12864b_page(unsigned char page)
141{
142 cfag12864b_di(state: 0);
143 cfag12864b_e(state: 1);
144 ks0108_page(page);
145 cfag12864b_e(state: 0);
146}
147
148static void cfag12864b_startline(unsigned char startline)
149{
150 cfag12864b_di(state: 0);
151 cfag12864b_e(state: 1);
152 ks0108_startline(startline);
153 cfag12864b_e(state: 0);
154}
155
156static void cfag12864b_writebyte(unsigned char byte)
157{
158 cfag12864b_di(state: 1);
159 cfag12864b_e(state: 1);
160 ks0108_writedata(byte);
161 cfag12864b_e(state: 0);
162}
163
164static void cfag12864b_nop(void)
165{
166 cfag12864b_startline(startline: 0);
167}
168
169/*
170 * cfag12864b Internal Commands
171 */
172
173static void cfag12864b_on(void)
174{
175 cfag12864b_setcontrollers(first: 1, second: 1);
176 cfag12864b_displaystate(state: 1);
177}
178
179static void cfag12864b_off(void)
180{
181 cfag12864b_setcontrollers(first: 1, second: 1);
182 cfag12864b_displaystate(state: 0);
183}
184
185static void cfag12864b_clear(void)
186{
187 unsigned char i, j;
188
189 cfag12864b_setcontrollers(first: 1, second: 1);
190 for (i = 0; i < CFAG12864B_PAGES; i++) {
191 cfag12864b_page(page: i);
192 cfag12864b_address(address: 0);
193 for (j = 0; j < CFAG12864B_ADDRESSES; j++)
194 cfag12864b_writebyte(byte: 0);
195 }
196}
197
198/*
199 * Update work
200 */
201
202unsigned char *cfag12864b_buffer;
203static unsigned char *cfag12864b_cache;
204static DEFINE_MUTEX(cfag12864b_mutex);
205static unsigned char cfag12864b_updating;
206static void cfag12864b_update(struct work_struct *delayed_work);
207static struct workqueue_struct *cfag12864b_workqueue;
208static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update);
209
210static void cfag12864b_queue(void)
211{
212 queue_delayed_work(wq: cfag12864b_workqueue, dwork: &cfag12864b_work,
213 HZ / cfag12864b_rate);
214}
215
216unsigned char cfag12864b_enable(void)
217{
218 unsigned char ret;
219
220 mutex_lock(&cfag12864b_mutex);
221
222 if (!cfag12864b_updating) {
223 cfag12864b_updating = 1;
224 cfag12864b_queue();
225 ret = 0;
226 } else
227 ret = 1;
228
229 mutex_unlock(lock: &cfag12864b_mutex);
230
231 return ret;
232}
233
234void cfag12864b_disable(void)
235{
236 mutex_lock(&cfag12864b_mutex);
237
238 if (cfag12864b_updating) {
239 cfag12864b_updating = 0;
240 cancel_delayed_work(dwork: &cfag12864b_work);
241 flush_workqueue(cfag12864b_workqueue);
242 }
243
244 mutex_unlock(lock: &cfag12864b_mutex);
245}
246
247static void cfag12864b_update(struct work_struct *work)
248{
249 unsigned char c;
250 unsigned short i, j, k, b;
251
252 if (memcmp(p: cfag12864b_cache, q: cfag12864b_buffer, CFAG12864B_SIZE)) {
253 for (i = 0; i < CFAG12864B_CONTROLLERS; i++) {
254 cfag12864b_controller(which: i);
255 cfag12864b_nop();
256 for (j = 0; j < CFAG12864B_PAGES; j++) {
257 cfag12864b_page(page: j);
258 cfag12864b_nop();
259 cfag12864b_address(address: 0);
260 cfag12864b_nop();
261 for (k = 0; k < CFAG12864B_ADDRESSES; k++) {
262 for (c = 0, b = 0; b < 8; b++)
263 if (cfag12864b_buffer
264 [i * CFAG12864B_ADDRESSES / 8
265 + k / 8 + (j * 8 + b) *
266 CFAG12864B_WIDTH / 8]
267 & bit(k % 8))
268 c |= bit(b);
269 cfag12864b_writebyte(byte: c);
270 }
271 }
272 }
273
274 memcpy(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE);
275 }
276
277 if (cfag12864b_updating)
278 cfag12864b_queue();
279}
280
281/*
282 * cfag12864b Exported Symbols
283 */
284
285EXPORT_SYMBOL_GPL(cfag12864b_buffer);
286EXPORT_SYMBOL_GPL(cfag12864b_enable);
287EXPORT_SYMBOL_GPL(cfag12864b_disable);
288
289/*
290 * Is the module inited?
291 */
292
293static unsigned char cfag12864b_inited;
294unsigned char cfag12864b_isinited(void)
295{
296 return cfag12864b_inited;
297}
298EXPORT_SYMBOL_GPL(cfag12864b_isinited);
299
300/*
301 * Module Init & Exit
302 */
303
304static int __init cfag12864b_init(void)
305{
306 int ret = -EINVAL;
307
308 /* ks0108_init() must be called first */
309 if (!ks0108_isinited()) {
310 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
311 "ks0108 is not initialized\n");
312 goto none;
313 }
314 BUILD_BUG_ON(PAGE_SIZE < CFAG12864B_SIZE);
315
316 cfag12864b_buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
317 if (cfag12864b_buffer == NULL) {
318 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
319 "can't get a free page\n");
320 ret = -ENOMEM;
321 goto none;
322 }
323
324 cfag12864b_cache = kmalloc(CFAG12864B_SIZE,
325 GFP_KERNEL);
326 if (cfag12864b_cache == NULL) {
327 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
328 "can't alloc cache buffer (%i bytes)\n",
329 CFAG12864B_SIZE);
330 ret = -ENOMEM;
331 goto bufferalloced;
332 }
333
334 cfag12864b_workqueue = create_singlethread_workqueue(CFAG12864B_NAME);
335 if (cfag12864b_workqueue == NULL)
336 goto cachealloced;
337
338 cfag12864b_clear();
339 cfag12864b_on();
340
341 cfag12864b_inited = 1;
342 return 0;
343
344cachealloced:
345 kfree(objp: cfag12864b_cache);
346
347bufferalloced:
348 free_page((unsigned long) cfag12864b_buffer);
349
350none:
351 return ret;
352}
353
354static void __exit cfag12864b_exit(void)
355{
356 cfag12864b_disable();
357 cfag12864b_off();
358 destroy_workqueue(wq: cfag12864b_workqueue);
359 kfree(objp: cfag12864b_cache);
360 free_page((unsigned long) cfag12864b_buffer);
361}
362
363module_init(cfag12864b_init);
364module_exit(cfag12864b_exit);
365
366MODULE_LICENSE("GPL v2");
367MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
368MODULE_DESCRIPTION("cfag12864b LCD driver");
369

source code of linux/drivers/auxdisplay/cfag12864b.c