drivers/auxdisplay/cfag12864b.c

   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/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         BUILD_BUG_ON(PAGE_SIZE < CFAG12864B_SIZE);
 340
 341         cfag12864b_buffer = (unsigned char *) get_zeroed_page(GFP_KERNEL);
 342         if (cfag12864b_buffer == NULL) {
 343                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
 344                         "can't get a free page\n");
 345                 ret = -ENOMEM;
 346                 goto none;
 347         }
 348
 349         cfag12864b_cache = kmalloc(sizeof(unsigned char) *
 350                 CFAG12864B_SIZE, GFP_KERNEL);
 351         if (cfag12864b_cache == NULL) {
 352                 printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
 353                         "can't alloc cache buffer (%i bytes)\n",
 354                         CFAG12864B_SIZE);
 355                 ret = -ENOMEM;
 356                 goto bufferalloced;
 357         }
 358
 359         cfag12864b_workqueue = create_singlethread_workqueue(CFAG12864B_NAME);
 360         if (cfag12864b_workqueue == NULL)
 361                 goto cachealloced;
 362
 363         cfag12864b_clear();
 364         cfag12864b_on();
 365
 366         cfag12864b_inited = 1;
 367         return 0;
 368
 369 cachealloced:
 370         kfree(cfag12864b_cache);
 371
 372 bufferalloced:
 373         free_page((unsigned long) cfag12864b_buffer);
 374
 375 none:
 376         return ret;
 377 }
 378
 379 static void __exit cfag12864b_exit(void)
 380 {
 381         cfag12864b_disable();
 382         cfag12864b_off();
 383         destroy_workqueue(cfag12864b_workqueue);
 384         kfree(cfag12864b_cache);
 385         free_page((unsigned long) cfag12864b_buffer);
 386 }
 387
 388 module_init(cfag12864b_init);
 389 module_exit(cfag12864b_exit);
 390
 391 MODULE_LICENSE("GPL v2");
 392 MODULE_AUTHOR("Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>");
 393 MODULE_DESCRIPTION("cfag12864b LCD driver");