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cfag12864b.c
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1 /*
2  * Filename: cfag12864b.c
3  * Version: 0.1.0
4  * Description: cfag12864b LCD driver
5  * License: GPLv2
6  * Depends: ks0108
7  *
8  * Author: Copyright (C) Miguel Ojeda Sandonis
9  * Date: 2006-10-31
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23  *
24  */
25 
26 #include <linux/init.h>
27 #include <linux/module.h>
28 #include <linux/kernel.h>
29 #include <linux/fs.h>
30 #include <linux/slab.h>
31 #include <linux/cdev.h>
32 #include <linux/delay.h>
33 #include <linux/device.h>
34 #include <linux/jiffies.h>
35 #include <linux/mutex.h>
36 #include <linux/uaccess.h>
37 #include <linux/vmalloc.h>
38 #include <linux/workqueue.h>
39 #include <linux/ks0108.h>
40 #include <linux/cfag12864b.h>
41 
42 
43 #define CFAG12864B_NAME "cfag12864b"
44 
45 /*
46  * Module Parameters
47  */
48 
49 static unsigned int cfag12864b_rate = CONFIG_CFAG12864B_RATE;
50 module_param(cfag12864b_rate, uint, S_IRUGO);
51 MODULE_PARM_DESC(cfag12864b_rate,
52  "Refresh rate (hertz)");
53 
54 unsigned int cfag12864b_getrate(void)
55 {
56  return cfag12864b_rate;
57 }
58 
59 /*
60  * cfag12864b Commands
61  *
62  * E = Enable signal
63  * Every time E switch from low to high,
64  * cfag12864b/ks0108 reads the command/data.
65  *
66  * CS1 = First ks0108controller.
67  * If high, the first ks0108 controller receives commands/data.
68  *
69  * CS2 = Second ks0108 controller
70  * If high, the second ks0108 controller receives commands/data.
71  *
72  * DI = Data/Instruction
73  * If low, cfag12864b will expect commands.
74  * If high, cfag12864b will expect data.
75  *
76  */
77 
78 #define bit(n) (((unsigned char)1)<<(n))
79 
80 #define CFAG12864B_BIT_E (0)
81 #define CFAG12864B_BIT_CS1 (2)
82 #define CFAG12864B_BIT_CS2 (1)
83 #define CFAG12864B_BIT_DI (3)
84 
85 static unsigned char cfag12864b_state;
86 
87 static void cfag12864b_set(void)
88 {
89  ks0108_writecontrol(cfag12864b_state);
90 }
91 
92 static void cfag12864b_setbit(unsigned char state, unsigned char n)
93 {
94  if (state)
95  cfag12864b_state |= bit(n);
96  else
97  cfag12864b_state &= ~bit(n);
98 }
99 
100 static void cfag12864b_e(unsigned char state)
101 {
102  cfag12864b_setbit(state, CFAG12864B_BIT_E);
103  cfag12864b_set();
104 }
105 
106 static void cfag12864b_cs1(unsigned char state)
107 {
108  cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
109 }
110 
111 static void cfag12864b_cs2(unsigned char state)
112 {
113  cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
114 }
115 
116 static void cfag12864b_di(unsigned char state)
117 {
118  cfag12864b_setbit(state, CFAG12864B_BIT_DI);
119 }
120 
121 static void cfag12864b_setcontrollers(unsigned char first,
122  unsigned char second)
123 {
124  if (first)
125  cfag12864b_cs1(0);
126  else
127  cfag12864b_cs1(1);
128 
129  if (second)
130  cfag12864b_cs2(0);
131  else
132  cfag12864b_cs2(1);
133 }
134 
135 static void cfag12864b_controller(unsigned char which)
136 {
137  if (which == 0)
138  cfag12864b_setcontrollers(1, 0);
139  else if (which == 1)
140  cfag12864b_setcontrollers(0, 1);
141 }
142 
143 static void cfag12864b_displaystate(unsigned char state)
144 {
145  cfag12864b_di(0);
146  cfag12864b_e(1);
147  ks0108_displaystate(state);
148  cfag12864b_e(0);
149 }
150 
151 static void cfag12864b_address(unsigned char address)
152 {
153  cfag12864b_di(0);
154  cfag12864b_e(1);
155  ks0108_address(address);
156  cfag12864b_e(0);
157 }
158 
159 static void cfag12864b_page(unsigned char page)
160 {
161  cfag12864b_di(0);
162  cfag12864b_e(1);
163  ks0108_page(page);
164  cfag12864b_e(0);
165 }
166 
167 static void cfag12864b_startline(unsigned char startline)
168 {
169  cfag12864b_di(0);
170  cfag12864b_e(1);
171  ks0108_startline(startline);
172  cfag12864b_e(0);
173 }
174 
175 static void cfag12864b_writebyte(unsigned char byte)
176 {
177  cfag12864b_di(1);
178  cfag12864b_e(1);
179  ks0108_writedata(byte);
180  cfag12864b_e(0);
181 }
182 
183 static void cfag12864b_nop(void)
184 {
185  cfag12864b_startline(0);
186 }
187 
188 /*
189  * cfag12864b Internal Commands
190  */
191 
192 static void cfag12864b_on(void)
193 {
194  cfag12864b_setcontrollers(1, 1);
195  cfag12864b_displaystate(1);
196 }
197 
198 static void cfag12864b_off(void)
199 {
200  cfag12864b_setcontrollers(1, 1);
201  cfag12864b_displaystate(0);
202 }
203 
204 static void cfag12864b_clear(void)
205 {
206  unsigned char i, j;
207 
208  cfag12864b_setcontrollers(1, 1);
209  for (i = 0; i < CFAG12864B_PAGES; i++) {
210  cfag12864b_page(i);
211  cfag12864b_address(0);
212  for (j = 0; j < CFAG12864B_ADDRESSES; j++)
213  cfag12864b_writebyte(0);
214  }
215 }
216 
217 /*
218  * Update work
219  */
220 
221 unsigned char *cfag12864b_buffer;
222 static unsigned char *cfag12864b_cache;
223 static DEFINE_MUTEX(cfag12864b_mutex);
224 static unsigned char cfag12864b_updating;
225 static void cfag12864b_update(struct work_struct *delayed_work);
226 static struct workqueue_struct *cfag12864b_workqueue;
227 static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update);
228 
229 static void cfag12864b_queue(void)
230 {
231  queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work,
232  HZ / cfag12864b_rate);
233 }
234 
235 unsigned char cfag12864b_enable(void)
236 {
237  unsigned char ret;
238 
239  mutex_lock(&cfag12864b_mutex);
240 
241  if (!cfag12864b_updating) {
242  cfag12864b_updating = 1;
243  cfag12864b_queue();
244  ret = 0;
245  } else
246  ret = 1;
247 
248  mutex_unlock(&cfag12864b_mutex);
249 
250  return ret;
251 }
252 
254 {
255  mutex_lock(&cfag12864b_mutex);
256 
257  if (cfag12864b_updating) {
258  cfag12864b_updating = 0;
259  cancel_delayed_work(&cfag12864b_work);
260  flush_workqueue(cfag12864b_workqueue);
261  }
262 
263  mutex_unlock(&cfag12864b_mutex);
264 }
265 
266 unsigned char cfag12864b_isenabled(void)
267 {
268  return cfag12864b_updating;
269 }
270 
271 static void cfag12864b_update(struct work_struct *work)
272 {
273  unsigned char c;
274  unsigned short i, j, k, b;
275 
276  if (memcmp(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE)) {
277  for (i = 0; i < CFAG12864B_CONTROLLERS; i++) {
278  cfag12864b_controller(i);
279  cfag12864b_nop();
280  for (j = 0; j < CFAG12864B_PAGES; j++) {
281  cfag12864b_page(j);
282  cfag12864b_nop();
283  cfag12864b_address(0);
284  cfag12864b_nop();
285  for (k = 0; k < CFAG12864B_ADDRESSES; k++) {
286  for (c = 0, b = 0; b < 8; b++)
287  if (cfag12864b_buffer
288  [i * CFAG12864B_ADDRESSES / 8
289  + k / 8 + (j * 8 + b) *
290  CFAG12864B_WIDTH / 8]
291  & bit(k % 8))
292  c |= bit(b);
293  cfag12864b_writebyte(c);
294  }
295  }
296  }
297 
298  memcpy(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE);
299  }
300 
301  if (cfag12864b_updating)
302  cfag12864b_queue();
303 }
304 
305 /*
306  * cfag12864b Exported Symbols
307  */
308 
309 EXPORT_SYMBOL_GPL(cfag12864b_buffer);
314 
315 /*
316  * Is the module inited?
317  */
318 
319 static unsigned char cfag12864b_inited;
320 unsigned char cfag12864b_isinited(void)
321 {
322  return cfag12864b_inited;
323 }
325 
326 /*
327  * Module Init & Exit
328  */
329 
330 static int __init cfag12864b_init(void)
331 {
332  int ret = -EINVAL;
333 
334  /* ks0108_init() must be called first */
335  if (!ks0108_isinited()) {
336  printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
337  "ks0108 is not initialized\n");
338  goto none;
339  }
341 
342  cfag12864b_buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
343  if (cfag12864b_buffer == NULL) {
344  printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
345  "can't get a free page\n");
346  ret = -ENOMEM;
347  goto none;
348  }
349 
350  cfag12864b_cache = kmalloc(sizeof(unsigned char) *
352  if (cfag12864b_cache == NULL) {
353  printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
354  "can't alloc cache buffer (%i bytes)\n",
356  ret = -ENOMEM;
357  goto bufferalloced;
358  }
359 
360  cfag12864b_workqueue = create_singlethread_workqueue(CFAG12864B_NAME);
361  if (cfag12864b_workqueue == NULL)
362  goto cachealloced;
363 
364  cfag12864b_clear();
365  cfag12864b_on();
366 
367  cfag12864b_inited = 1;
368  return 0;
369 
370 cachealloced:
371  kfree(cfag12864b_cache);
372 
373 bufferalloced:
374  free_page((unsigned long) cfag12864b_buffer);
375 
376 none:
377  return ret;
378 }
379 
380 static void __exit cfag12864b_exit(void)
381 {
383  cfag12864b_off();
384  destroy_workqueue(cfag12864b_workqueue);
385  kfree(cfag12864b_cache);
386  free_page((unsigned long) cfag12864b_buffer);
387 }
388 
389 module_init(cfag12864b_init);
390 module_exit(cfag12864b_exit);
391 
392 MODULE_LICENSE("GPL v2");
393 MODULE_AUTHOR("Miguel Ojeda Sandonis <[email protected]>");
394 MODULE_DESCRIPTION("cfag12864b LCD driver");