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
35 static unsigned int cfag12864b_rate = CONFIG_CFAG12864B_RATE;
36 module_param(cfag12864b_rate, uint, 0444);
37 MODULE_PARM_DESC(cfag12864b_rate,
38 "Refresh rate (hertz)");
39
cfag12864b_getrate(void)40 unsigned int cfag12864b_getrate(void)
41 {
42 return cfag12864b_rate;
43 }
44
45 /*
46 * cfag12864b Commands
47 *
48 * E = Enable signal
49 * Every time E switch from low to high,
50 * cfag12864b/ks0108 reads the command/data.
51 *
52 * CS1 = First ks0108controller.
53 * If high, the first ks0108 controller receives commands/data.
54 *
55 * CS2 = Second ks0108 controller
56 * If high, the second ks0108 controller receives commands/data.
57 *
58 * DI = Data/Instruction
59 * If low, cfag12864b will expect commands.
60 * If high, cfag12864b will expect data.
61 *
62 */
63
64 #define bit(n) (((unsigned char)1)<<(n))
65
66 #define CFAG12864B_BIT_E (0)
67 #define CFAG12864B_BIT_CS1 (2)
68 #define CFAG12864B_BIT_CS2 (1)
69 #define CFAG12864B_BIT_DI (3)
70
71 static unsigned char cfag12864b_state;
72
cfag12864b_set(void)73 static void cfag12864b_set(void)
74 {
75 ks0108_writecontrol(cfag12864b_state);
76 }
77
cfag12864b_setbit(unsigned char state,unsigned char n)78 static void cfag12864b_setbit(unsigned char state, unsigned char n)
79 {
80 if (state)
81 cfag12864b_state |= bit(n);
82 else
83 cfag12864b_state &= ~bit(n);
84 }
85
cfag12864b_e(unsigned char state)86 static void cfag12864b_e(unsigned char state)
87 {
88 cfag12864b_setbit(state, CFAG12864B_BIT_E);
89 cfag12864b_set();
90 }
91
cfag12864b_cs1(unsigned char state)92 static void cfag12864b_cs1(unsigned char state)
93 {
94 cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
95 }
96
cfag12864b_cs2(unsigned char state)97 static void cfag12864b_cs2(unsigned char state)
98 {
99 cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
100 }
101
cfag12864b_di(unsigned char state)102 static void cfag12864b_di(unsigned char state)
103 {
104 cfag12864b_setbit(state, CFAG12864B_BIT_DI);
105 }
106
cfag12864b_setcontrollers(unsigned char first,unsigned char second)107 static void cfag12864b_setcontrollers(unsigned char first,
108 unsigned char second)
109 {
110 if (first)
111 cfag12864b_cs1(0);
112 else
113 cfag12864b_cs1(1);
114
115 if (second)
116 cfag12864b_cs2(0);
117 else
118 cfag12864b_cs2(1);
119 }
120
cfag12864b_controller(unsigned char which)121 static void cfag12864b_controller(unsigned char which)
122 {
123 if (which == 0)
124 cfag12864b_setcontrollers(1, 0);
125 else if (which == 1)
126 cfag12864b_setcontrollers(0, 1);
127 }
128
cfag12864b_displaystate(unsigned char state)129 static void cfag12864b_displaystate(unsigned char state)
130 {
131 cfag12864b_di(0);
132 cfag12864b_e(1);
133 ks0108_displaystate(state);
134 cfag12864b_e(0);
135 }
136
cfag12864b_address(unsigned char address)137 static void cfag12864b_address(unsigned char address)
138 {
139 cfag12864b_di(0);
140 cfag12864b_e(1);
141 ks0108_address(address);
142 cfag12864b_e(0);
143 }
144
cfag12864b_page(unsigned char page)145 static void cfag12864b_page(unsigned char page)
146 {
147 cfag12864b_di(0);
148 cfag12864b_e(1);
149 ks0108_page(page);
150 cfag12864b_e(0);
151 }
152
cfag12864b_startline(unsigned char startline)153 static void cfag12864b_startline(unsigned char startline)
154 {
155 cfag12864b_di(0);
156 cfag12864b_e(1);
157 ks0108_startline(startline);
158 cfag12864b_e(0);
159 }
160
cfag12864b_writebyte(unsigned char byte)161 static void cfag12864b_writebyte(unsigned char byte)
162 {
163 cfag12864b_di(1);
164 cfag12864b_e(1);
165 ks0108_writedata(byte);
166 cfag12864b_e(0);
167 }
168
cfag12864b_nop(void)169 static void cfag12864b_nop(void)
170 {
171 cfag12864b_startline(0);
172 }
173
174 /*
175 * cfag12864b Internal Commands
176 */
177
cfag12864b_on(void)178 static void cfag12864b_on(void)
179 {
180 cfag12864b_setcontrollers(1, 1);
181 cfag12864b_displaystate(1);
182 }
183
cfag12864b_off(void)184 static void cfag12864b_off(void)
185 {
186 cfag12864b_setcontrollers(1, 1);
187 cfag12864b_displaystate(0);
188 }
189
cfag12864b_clear(void)190 static void cfag12864b_clear(void)
191 {
192 unsigned char i, j;
193
194 cfag12864b_setcontrollers(1, 1);
195 for (i = 0; i < CFAG12864B_PAGES; i++) {
196 cfag12864b_page(i);
197 cfag12864b_address(0);
198 for (j = 0; j < CFAG12864B_ADDRESSES; j++)
199 cfag12864b_writebyte(0);
200 }
201 }
202
203 /*
204 * Update work
205 */
206
207 unsigned char *cfag12864b_buffer;
208 static unsigned char *cfag12864b_cache;
209 static DEFINE_MUTEX(cfag12864b_mutex);
210 static unsigned char cfag12864b_updating;
211 static void cfag12864b_update(struct work_struct *delayed_work);
212 static struct workqueue_struct *cfag12864b_workqueue;
213 static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update);
214
cfag12864b_queue(void)215 static void cfag12864b_queue(void)
216 {
217 queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work,
218 HZ / cfag12864b_rate);
219 }
220
cfag12864b_enable(void)221 unsigned char cfag12864b_enable(void)
222 {
223 unsigned char ret;
224
225 mutex_lock(&cfag12864b_mutex);
226
227 if (!cfag12864b_updating) {
228 cfag12864b_updating = 1;
229 cfag12864b_queue();
230 ret = 0;
231 } else
232 ret = 1;
233
234 mutex_unlock(&cfag12864b_mutex);
235
236 return ret;
237 }
238
cfag12864b_disable(void)239 void cfag12864b_disable(void)
240 {
241 mutex_lock(&cfag12864b_mutex);
242
243 if (cfag12864b_updating) {
244 cfag12864b_updating = 0;
245 cancel_delayed_work(&cfag12864b_work);
246 flush_workqueue(cfag12864b_workqueue);
247 }
248
249 mutex_unlock(&cfag12864b_mutex);
250 }
251
cfag12864b_isenabled(void)252 unsigned char cfag12864b_isenabled(void)
253 {
254 return cfag12864b_updating;
255 }
256
cfag12864b_update(struct work_struct * work)257 static void cfag12864b_update(struct work_struct *work)
258 {
259 unsigned char c;
260 unsigned short i, j, k, b;
261
262 if (memcmp(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE)) {
263 for (i = 0; i < CFAG12864B_CONTROLLERS; i++) {
264 cfag12864b_controller(i);
265 cfag12864b_nop();
266 for (j = 0; j < CFAG12864B_PAGES; j++) {
267 cfag12864b_page(j);
268 cfag12864b_nop();
269 cfag12864b_address(0);
270 cfag12864b_nop();
271 for (k = 0; k < CFAG12864B_ADDRESSES; k++) {
272 for (c = 0, b = 0; b < 8; b++)
273 if (cfag12864b_buffer
274 [i * CFAG12864B_ADDRESSES / 8
275 + k / 8 + (j * 8 + b) *
276 CFAG12864B_WIDTH / 8]
277 & bit(k % 8))
278 c |= bit(b);
279 cfag12864b_writebyte(c);
280 }
281 }
282 }
283
284 memcpy(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE);
285 }
286
287 if (cfag12864b_updating)
288 cfag12864b_queue();
289 }
290
291 /*
292 * cfag12864b Exported Symbols
293 */
294
295 EXPORT_SYMBOL_GPL(cfag12864b_buffer);
296 EXPORT_SYMBOL_GPL(cfag12864b_getrate);
297 EXPORT_SYMBOL_GPL(cfag12864b_enable);
298 EXPORT_SYMBOL_GPL(cfag12864b_disable);
299 EXPORT_SYMBOL_GPL(cfag12864b_isenabled);
300
301 /*
302 * Is the module inited?
303 */
304
305 static unsigned char cfag12864b_inited;
cfag12864b_isinited(void)306 unsigned char cfag12864b_isinited(void)
307 {
308 return cfag12864b_inited;
309 }
310 EXPORT_SYMBOL_GPL(cfag12864b_isinited);
311
312 /*
313 * Module Init & Exit
314 */
315
cfag12864b_init(void)316 static int __init cfag12864b_init(void)
317 {
318 int ret = -EINVAL;
319
320 /* ks0108_init() must be called first */
321 if (!ks0108_isinited()) {
322 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
323 "ks0108 is not initialized\n");
324 goto none;
325 }
326 BUILD_BUG_ON(PAGE_SIZE < CFAG12864B_SIZE);
327
328 cfag12864b_buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
329 if (cfag12864b_buffer == NULL) {
330 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
331 "can't get a free page\n");
332 ret = -ENOMEM;
333 goto none;
334 }
335
336 cfag12864b_cache = kmalloc(CFAG12864B_SIZE,
337 GFP_KERNEL);
338 if (cfag12864b_cache == NULL) {
339 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
340 "can't alloc cache buffer (%i bytes)\n",
341 CFAG12864B_SIZE);
342 ret = -ENOMEM;
343 goto bufferalloced;
344 }
345
346 cfag12864b_workqueue = create_singlethread_workqueue(CFAG12864B_NAME);
347 if (cfag12864b_workqueue == NULL)
348 goto cachealloced;
349
350 cfag12864b_clear();
351 cfag12864b_on();
352
353 cfag12864b_inited = 1;
354 return 0;
355
356 cachealloced:
357 kfree(cfag12864b_cache);
358
359 bufferalloced:
360 free_page((unsigned long) cfag12864b_buffer);
361
362 none:
363 return ret;
364 }
365
cfag12864b_exit(void)366 static void __exit cfag12864b_exit(void)
367 {
368 cfag12864b_disable();
369 cfag12864b_off();
370 destroy_workqueue(cfag12864b_workqueue);
371 kfree(cfag12864b_cache);
372 free_page((unsigned long) cfag12864b_buffer);
373 }
374
375 module_init(cfag12864b_init);
376 module_exit(cfag12864b_exit);
377
378 MODULE_LICENSE("GPL v2");
379 MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
380 MODULE_DESCRIPTION("cfag12864b LCD driver");
381