Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  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 <maxextreme@gmail.com>
  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/cdev.h>
 31 #include <linux/delay.h>
 32 #include <linux/device.h>
 33 #include <linux/jiffies.h>
 34 #include <linux/mutex.h>
 35 #include <linux/uaccess.h>
 36 #include <linux/vmalloc.h>
 37 #include <linux/workqueue.h>
 38 #include <linux/ks0108.h>
 39 #include <linux/cfag12864b.h>
 40 
 41 
 42 #define CFAG12864B_NAME "cfag12864b"
 43 
 44 /*
 45  * Module Parameters
 46  */
 47 
 48 static unsigned int cfag12864b_rate = CONFIG_CFAG12864B_RATE;
 49 module_param(cfag12864b_rate, uint, S_IRUGO);
 50 MODULE_PARM_DESC(cfag12864b_rate,
 51         "Refresh rate (hertzs)");
 52 
 53 unsigned int cfag12864b_getrate(void)
 54 {
 55         return cfag12864b_rate;
 56 }
 57 
 58 /*
 59  * cfag12864b Commands
 60  *
 61  *      E = Enable signal
 62  *              Everytime E switch from low to high,
 63  *              cfag12864b/ks0108 reads the command/data.
 64  *
 65  *      CS1 = First ks0108controller.
 66  *              If high, the first ks0108 controller receives commands/data.
 67  *
 68  *      CS2 = Second ks0108 controller
 69  *              If high, the second ks0108 controller receives commands/data.
 70  *
 71  *      DI = Data/Instruction
 72  *              If low, cfag12864b will expect commands.
 73  *              If high, cfag12864b will expect data.
 74  *
 75  */
 76 
 77 #define bit(n) (((unsigned char)1)<<(n))
 78 
 79 #define CFAG12864B_BIT_E        (0)
 80 #define CFAG12864B_BIT_CS1      (2)
 81 #define CFAG12864B_BIT_CS2      (1)
 82 #define CFAG12864B_BIT_DI       (3)
 83 
 84 static unsigned char cfag12864b_state;
 85 
 86 static void cfag12864b_set(void)
 87 {
 88         ks0108_writecontrol(cfag12864b_state);
 89 }
 90 
 91 static void cfag12864b_setbit(unsigned char state, unsigned char n)
 92 {
 93         if (state)
 94                 cfag12864b_state |= bit(n);
 95         else
 96                 cfag12864b_state &= ~bit(n);
 97 }
 98 
 99 static void cfag12864b_e(unsigned char state)
100 {
101         cfag12864b_setbit(state, CFAG12864B_BIT_E);
102         cfag12864b_set();
103 }
104 
105 static void cfag12864b_cs1(unsigned char state)
106 {
107         cfag12864b_setbit(state, CFAG12864B_BIT_CS1);
108 }
109 
110 static void cfag12864b_cs2(unsigned char state)
111 {
112         cfag12864b_setbit(state, CFAG12864B_BIT_CS2);
113 }
114 
115 static void cfag12864b_di(unsigned char state)
116 {
117         cfag12864b_setbit(state, CFAG12864B_BIT_DI);
118 }
119 
120 static void cfag12864b_setcontrollers(unsigned char first,
121         unsigned char second)
122 {
123         if (first)
124                 cfag12864b_cs1(0);
125         else
126                 cfag12864b_cs1(1);
127 
128         if (second)
129                 cfag12864b_cs2(0);
130         else
131                 cfag12864b_cs2(1);
132 }
133 
134 static void cfag12864b_controller(unsigned char which)
135 {
136         if (which == 0)
137                 cfag12864b_setcontrollers(1, 0);
138         else if (which == 1)
139                 cfag12864b_setcontrollers(0, 1);
140 }
141 
142 static void cfag12864b_displaystate(unsigned char state)
143 {
144         cfag12864b_di(0);
145         cfag12864b_e(1);
146         ks0108_displaystate(state);
147         cfag12864b_e(0);
148 }
149 
150 static void cfag12864b_address(unsigned char address)
151 {
152         cfag12864b_di(0);
153         cfag12864b_e(1);
154         ks0108_address(address);
155         cfag12864b_e(0);
156 }
157 
158 static void cfag12864b_page(unsigned char page)
159 {
160         cfag12864b_di(0);
161         cfag12864b_e(1);
162         ks0108_page(page);
163         cfag12864b_e(0);
164 }
165 
166 static void cfag12864b_startline(unsigned char startline)
167 {
168         cfag12864b_di(0);
169         cfag12864b_e(1);
170         ks0108_startline(startline);
171         cfag12864b_e(0);
172 }
173 
174 static void cfag12864b_writebyte(unsigned char byte)
175 {
176         cfag12864b_di(1);
177         cfag12864b_e(1);
178         ks0108_writedata(byte);
179         cfag12864b_e(0);
180 }
181 
182 static void cfag12864b_nop(void)
183 {
184         cfag12864b_startline(0);
185 }
186 
187 /*
188  * cfag12864b Internal Commands
189  */
190 
191 static void cfag12864b_on(void)
192 {
193         cfag12864b_setcontrollers(1, 1);
194         cfag12864b_displaystate(1);
195 }
196 
197 static void cfag12864b_off(void)
198 {
199         cfag12864b_setcontrollers(1, 1);
200         cfag12864b_displaystate(0);
201 }
202 
203 static void cfag12864b_clear(void)
204 {
205         unsigned char i, j;
206 
207         cfag12864b_setcontrollers(1, 1);
208         for (i = 0; i < CFAG12864B_PAGES; i++) {
209                 cfag12864b_page(i);
210                 cfag12864b_address(0);
211                 for (j = 0; j < CFAG12864B_ADDRESSES; j++)
212                         cfag12864b_writebyte(0);
213         }
214 }
215 
216 /*
217  * Update work
218  */
219 
220 unsigned char *cfag12864b_buffer;
221 static unsigned char *cfag12864b_cache;
222 static DEFINE_MUTEX(cfag12864b_mutex);
223 static unsigned char cfag12864b_updating;
224 static void cfag12864b_update(struct work_struct *delayed_work);
225 static struct workqueue_struct *cfag12864b_workqueue;
226 static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update);
227 
228 static void cfag12864b_queue(void)
229 {
230         queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work,
231                 HZ / cfag12864b_rate);
232 }
233 
234 unsigned char cfag12864b_enable(void)
235 {
236         unsigned char ret;
237 
238         mutex_lock(&cfag12864b_mutex);
239 
240         if (!cfag12864b_updating) {
241                 cfag12864b_updating = 1;
242                 cfag12864b_queue();
243                 ret = 0;
244         } else
245                 ret = 1;
246 
247         mutex_unlock(&cfag12864b_mutex);
248 
249         return ret;
250 }
251 
252 void cfag12864b_disable(void)
253 {
254         mutex_lock(&cfag12864b_mutex);
255 
256         if (cfag12864b_updating) {
257                 cfag12864b_updating = 0;
258                 cancel_delayed_work(&cfag12864b_work);
259                 flush_workqueue(cfag12864b_workqueue);
260         }
261 
262         mutex_unlock(&cfag12864b_mutex);
263 }
264 
265 unsigned char cfag12864b_isenabled(void)
266 {
267         return cfag12864b_updating;
268 }
269 
270 static void cfag12864b_update(struct work_struct *work)
271 {
272         unsigned char c;
273         unsigned short i, j, k, b;
274 
275         if (memcmp(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE)) {
276                 for (i = 0; i < CFAG12864B_CONTROLLERS; i++) {
277                         cfag12864b_controller(i);
278                         cfag12864b_nop();
279                         for (j = 0; j < CFAG12864B_PAGES; j++) {
280                                 cfag12864b_page(j);
281                                 cfag12864b_nop();
282                                 cfag12864b_address(0);
283                                 cfag12864b_nop();
284                                 for (k = 0; k < CFAG12864B_ADDRESSES; k++) {
285                                         for (c = 0, b = 0; b < 8; b++)
286                                                 if (cfag12864b_buffer
287                                                         [i * CFAG12864B_ADDRESSES / 8
288                                                         + k / 8 + (j * 8 + b) *
289                                                         CFAG12864B_WIDTH / 8]
290                                                         & bit(k % 8))
291                                                         c |= bit(b);
292                                         cfag12864b_writebyte(c);
293                                 }
294                         }
295                 }
296 
297                 memcpy(cfag12864b_cache, cfag12864b_buffer, CFAG12864B_SIZE);
298         }
299 
300         if (cfag12864b_updating)
301                 cfag12864b_queue();
302 }
303 
304 /*
305  * cfag12864b Exported Symbols
306  */
307 
308 EXPORT_SYMBOL_GPL(cfag12864b_buffer);
309 EXPORT_SYMBOL_GPL(cfag12864b_getrate);
310 EXPORT_SYMBOL_GPL(cfag12864b_enable);
311 EXPORT_SYMBOL_GPL(cfag12864b_disable);
312 EXPORT_SYMBOL_GPL(cfag12864b_isenabled);
313 
314 /*
315  * Is the module inited?
316  */
317 
318 static unsigned char cfag12864b_inited;
319 unsigned char cfag12864b_isinited(void)
320 {
321         return cfag12864b_inited;
322 }
323 EXPORT_SYMBOL_GPL(cfag12864b_isinited);
324 
325 /*
326  * Module Init & Exit
327  */
328 
329 static int __init cfag12864b_init(void)
330 {
331         int ret = -EINVAL;
332 
333         /* ks0108_init() must be called first */
334         if (!ks0108_isinited()) {
335                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
336                         "ks0108 is not initialized\n");
337                 goto none;
338         }
339 
340         if (PAGE_SIZE < CFAG12864B_SIZE) {
341                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
342                         "page size (%i) < cfag12864b size (%i)\n",
343                         (unsigned int)PAGE_SIZE, CFAG12864B_SIZE);
344                 ret = -ENOMEM;
345                 goto none;
346         }
347 
348         cfag12864b_buffer = (unsigned char *) __get_free_page(GFP_KERNEL);
349         if (cfag12864b_buffer == NULL) {
350                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
351                         "can't get a free page\n");
352                 ret = -ENOMEM;
353                 goto none;
354         }
355 
356         cfag12864b_cache = kmalloc(sizeof(unsigned char) *
357                 CFAG12864B_SIZE, GFP_KERNEL);
358         if (cfag12864b_cache == NULL) {
359                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
360                         "can't alloc cache buffer (%i bytes)\n",
361                         CFAG12864B_SIZE);
362                 ret = -ENOMEM;
363                 goto bufferalloced;
364         }
365 
366         cfag12864b_workqueue = create_singlethread_workqueue(CFAG12864B_NAME);
367         if (cfag12864b_workqueue == NULL)
368                 goto cachealloced;
369 
370         memset(cfag12864b_buffer, 0, CFAG12864B_SIZE);
371 
372         cfag12864b_clear();
373         cfag12864b_on();
374 
375         cfag12864b_inited = 1;
376         return 0;
377 
378 cachealloced:
379         kfree(cfag12864b_cache);
380 
381 bufferalloced:
382         free_page((unsigned long) cfag12864b_buffer);
383 
384 none:
385         return ret;
386 }
387 
388 static void __exit cfag12864b_exit(void)
389 {
390         cfag12864b_disable();
391         cfag12864b_off();
392         destroy_workqueue(cfag12864b_workqueue);
393         kfree(cfag12864b_cache);
394         free_page((unsigned long) cfag12864b_buffer);
395 }
396 
397 module_init(cfag12864b_init);
398 module_exit(cfag12864b_exit);
399 
400 MODULE_LICENSE("GPL v2");
401 MODULE_AUTHOR("Miguel Ojeda Sandonis <maxextreme@gmail.com>");
402 MODULE_DESCRIPTION("cfag12864b LCD driver");
403 
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