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 Sandonis
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, S_IRUGO);
37 MODULE_PARM_DESC(cfag12864b_rate,
38 	"Refresh rate (hertz)");
39 
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 
73 static void cfag12864b_set(void)
74 {
75 	ks0108_writecontrol(cfag12864b_state);
76 }
77 
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 
86 static void cfag12864b_e(unsigned char state)
87 {
88 	cfag12864b_setbit(state, CFAG12864B_BIT_E);
89 	cfag12864b_set();
90 }
91 
92 static void cfag12864b_cs1(unsigned char state)
93 {
94 	cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
95 }
96 
97 static void cfag12864b_cs2(unsigned char state)
98 {
99 	cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
100 }
101 
102 static void cfag12864b_di(unsigned char state)
103 {
104 	cfag12864b_setbit(state, CFAG12864B_BIT_DI);
105 }
106 
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 
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 
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 
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 
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 
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 
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 
169 static void cfag12864b_nop(void)
170 {
171 	cfag12864b_startline(0);
172 }
173 
174 /*
175  * cfag12864b Internal Commands
176  */
177 
178 static void cfag12864b_on(void)
179 {
180 	cfag12864b_setcontrollers(1, 1);
181 	cfag12864b_displaystate(1);
182 }
183 
184 static void cfag12864b_off(void)
185 {
186 	cfag12864b_setcontrollers(1, 1);
187 	cfag12864b_displaystate(0);
188 }
189 
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 
215 static void cfag12864b_queue(void)
216 {
217 	queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work,
218 		HZ / cfag12864b_rate);
219 }
220 
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 
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 
252 unsigned char cfag12864b_isenabled(void)
253 {
254 	return cfag12864b_updating;
255 }
256 
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;
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 
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 
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 Sandonis <miguel.ojeda.sandonis@gmail.com>");
380 MODULE_DESCRIPTION("cfag12864b LCD driver");
381