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
40unsigned 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
71static unsigned char cfag12864b_state;
72
73static void cfag12864b_set(void)
74{
75	ks0108_writecontrol(cfag12864b_state);
76}
77
78static 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
86static void cfag12864b_e(unsigned char state)
87{
88	cfag12864b_setbit(state, CFAG12864B_BIT_E);
89	cfag12864b_set();
90}
91
92static void cfag12864b_cs1(unsigned char state)
93{
94	cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
95}
96
97static void cfag12864b_cs2(unsigned char state)
98{
99	cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
100}
101
102static void cfag12864b_di(unsigned char state)
103{
104	cfag12864b_setbit(state, CFAG12864B_BIT_DI);
105}
106
107static 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
121static 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
129static 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
137static 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
145static 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
153static 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
161static 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
169static void cfag12864b_nop(void)
170{
171	cfag12864b_startline(0);
172}
173
174/*
175 * cfag12864b Internal Commands
176 */
177
178static void cfag12864b_on(void)
179{
180	cfag12864b_setcontrollers(1, 1);
181	cfag12864b_displaystate(1);
182}
183
184static void cfag12864b_off(void)
185{
186	cfag12864b_setcontrollers(1, 1);
187	cfag12864b_displaystate(0);
188}
189
190static 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
207unsigned char *cfag12864b_buffer;
208static unsigned char *cfag12864b_cache;
209static DEFINE_MUTEX(cfag12864b_mutex);
210static unsigned char cfag12864b_updating;
211static void cfag12864b_update(struct work_struct *delayed_work);
212static struct workqueue_struct *cfag12864b_workqueue;
213static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update);
214
215static void cfag12864b_queue(void)
216{
217	queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work,
218		HZ / cfag12864b_rate);
219}
220
221unsigned 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
239void 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
252unsigned char cfag12864b_isenabled(void)
253{
254	return cfag12864b_updating;
255}
256
257static 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
295EXPORT_SYMBOL_GPL(cfag12864b_buffer);
296EXPORT_SYMBOL_GPL(cfag12864b_getrate);
297EXPORT_SYMBOL_GPL(cfag12864b_enable);
298EXPORT_SYMBOL_GPL(cfag12864b_disable);
299EXPORT_SYMBOL_GPL(cfag12864b_isenabled);
300
301/*
302 * Is the module inited?
303 */
304
305static unsigned char cfag12864b_inited;
306unsigned char cfag12864b_isinited(void)
307{
308	return cfag12864b_inited;
309}
310EXPORT_SYMBOL_GPL(cfag12864b_isinited);
311
312/*
313 * Module Init & Exit
314 */
315
316static 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
356cachealloced:
357	kfree(cfag12864b_cache);
358
359bufferalloced:
360	free_page((unsigned long) cfag12864b_buffer);
361
362none:
363	return ret;
364}
365
366static 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
375module_init(cfag12864b_init);
376module_exit(cfag12864b_exit);
377
378MODULE_LICENSE("GPL v2");
379MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>");
380MODULE_DESCRIPTION("cfag12864b LCD driver");
381