cfag12864b.c

  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(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(0);
107	else
108		cfag12864b_cs1(1);
109
110	if (second)
111		cfag12864b_cs2(0);
112	else
113		cfag12864b_cs2(1);
114}
115
116static void cfag12864b_controller(unsigned char which)
117{
118	if (which == 0)
119		cfag12864b_setcontrollers(1, 0);
120	else if (which == 1)
121		cfag12864b_setcontrollers(0, 1);
122}
123
124static void cfag12864b_displaystate(unsigned char state)
125{
126	cfag12864b_di(0);
127	cfag12864b_e(1);
128	ks0108_displaystate(state);
129	cfag12864b_e(0);
130}
131
132static void cfag12864b_address(unsigned char address)
133{
134	cfag12864b_di(0);
135	cfag12864b_e(1);
136	ks0108_address(address);
137	cfag12864b_e(0);
138}
139
140static void cfag12864b_page(unsigned char page)
141{
142	cfag12864b_di(0);
143	cfag12864b_e(1);
144	ks0108_page(page);
145	cfag12864b_e(0);
146}
147
148static void cfag12864b_startline(unsigned char startline)
149{
150	cfag12864b_di(0);
151	cfag12864b_e(1);
152	ks0108_startline(startline);
153	cfag12864b_e(0);
154}
155
156static void cfag12864b_writebyte(unsigned char byte)
157{
158	cfag12864b_di(1);
159	cfag12864b_e(1);
160	ks0108_writedata(byte);
161	cfag12864b_e(0);
162}
163
164static void cfag12864b_nop(void)
165{
166	cfag12864b_startline(0);
167}
168
169/*
170 * cfag12864b Internal Commands
171 */
172
173static void cfag12864b_on(void)
174{
175	cfag12864b_setcontrollers(1, 1);
176	cfag12864b_displaystate(1);
177}
178
179static void cfag12864b_off(void)
180{
181	cfag12864b_setcontrollers(1, 1);
182	cfag12864b_displaystate(0);
183}
184
185static void cfag12864b_clear(void)
186{
187	unsigned char i, j;
188
189	cfag12864b_setcontrollers(1, 1);
190	for (i = 0; i < CFAG12864B_PAGES; i++) {
191		cfag12864b_page(i);
192		cfag12864b_address(0);
193		for (j = 0; j < CFAG12864B_ADDRESSES; j++)
194			cfag12864b_writebyte(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(cfag12864b_workqueue, &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(&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(&cfag12864b_work);
241		flush_workqueue(cfag12864b_workqueue);
242	}
243
244	mutex_unlock(&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(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE)) {
253		for (i = 0; i < CFAG12864B_CONTROLLERS; i++) {
254			cfag12864b_controller(i);
255			cfag12864b_nop();
256			for (j = 0; j < CFAG12864B_PAGES; j++) {
257				cfag12864b_page(j);
258				cfag12864b_nop();
259				cfag12864b_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(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(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(cfag12864b_workqueue);
359	kfree(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");