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 35 static unsigned int cfag12864b_rate = CONFIG_CFAG12864B_RATE; 36 module_param(cfag12864b_rate, uint, 0444); 37 MODULE_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 66 static unsigned char cfag12864b_state; 67 68 static void cfag12864b_set(void) 69 { 70 ks0108_writecontrol(cfag12864b_state); 71 } 72 73 static 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 81 static void cfag12864b_e(unsigned char state) 82 { 83 cfag12864b_setbit(state, CFAG12864B_BIT_E); 84 cfag12864b_set(); 85 } 86 87 static void cfag12864b_cs1(unsigned char state) 88 { 89 cfag12864b_setbit(state, CFAG12864B_BIT_CS1); 90 } 91 92 static void cfag12864b_cs2(unsigned char state) 93 { 94 cfag12864b_setbit(state, CFAG12864B_BIT_CS2); 95 } 96 97 static void cfag12864b_di(unsigned char state) 98 { 99 cfag12864b_setbit(state, CFAG12864B_BIT_DI); 100 } 101 102 static 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 } 115 116 static 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 } 123 124 static void cfag12864b_displaystate(unsigned char state) 125 { 126 cfag12864b_di(0); 127 cfag12864b_e(1); 128 ks0108_displaystate(state); 129 cfag12864b_e(0); 130 } 131 132 static void cfag12864b_address(unsigned char address) 133 { 134 cfag12864b_di(0); 135 cfag12864b_e(1); 136 ks0108_address(address); 137 cfag12864b_e(0); 138 } 139 140 static void cfag12864b_page(unsigned char page) 141 { 142 cfag12864b_di(0); 143 cfag12864b_e(1); 144 ks0108_page(page); 145 cfag12864b_e(0); 146 } 147 148 static void cfag12864b_startline(unsigned char startline) 149 { 150 cfag12864b_di(0); 151 cfag12864b_e(1); 152 ks0108_startline(startline); 153 cfag12864b_e(0); 154 } 155 156 static void cfag12864b_writebyte(unsigned char byte) 157 { 158 cfag12864b_di(1); 159 cfag12864b_e(1); 160 ks0108_writedata(byte); 161 cfag12864b_e(0); 162 } 163 164 static void cfag12864b_nop(void) 165 { 166 cfag12864b_startline(0); 167 } 168 169 /* 170 * cfag12864b Internal Commands 171 */ 172 173 static void cfag12864b_on(void) 174 { 175 cfag12864b_setcontrollers(1, 1); 176 cfag12864b_displaystate(1); 177 } 178 179 static void cfag12864b_off(void) 180 { 181 cfag12864b_setcontrollers(1, 1); 182 cfag12864b_displaystate(0); 183 } 184 185 static 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 */ 201 202 unsigned char *cfag12864b_buffer; 203 static unsigned char *cfag12864b_cache; 204 static DEFINE_MUTEX(cfag12864b_mutex); 205 static unsigned char cfag12864b_updating; 206 static void cfag12864b_update(struct work_struct *delayed_work); 207 static struct workqueue_struct *cfag12864b_workqueue; 208 static DECLARE_DELAYED_WORK(cfag12864b_work, cfag12864b_update); 209 210 static void cfag12864b_queue(void) 211 { 212 queue_delayed_work(cfag12864b_workqueue, &cfag12864b_work, 213 HZ / cfag12864b_rate); 214 } 215 216 unsigned 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 } 233 234 void 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 } 246 247 static 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 */ 284 285 EXPORT_SYMBOL_GPL(cfag12864b_buffer); 286 EXPORT_SYMBOL_GPL(cfag12864b_enable); 287 EXPORT_SYMBOL_GPL(cfag12864b_disable); 288 289 /* 290 * Is the module inited? 291 */ 292 293 static unsigned char cfag12864b_inited; 294 unsigned char cfag12864b_isinited(void) 295 { 296 return cfag12864b_inited; 297 } 298 EXPORT_SYMBOL_GPL(cfag12864b_isinited); 299 300 /* 301 * Module Init & Exit 302 */ 303 304 static 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; 343 344 cachealloced: 345 kfree(cfag12864b_cache); 346 347 bufferalloced: 348 free_page((unsigned long) cfag12864b_buffer); 349 350 none: 351 return ret; 352 } 353 354 static 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 } 362 363 module_init(cfag12864b_init); 364 module_exit(cfag12864b_exit); 365 366 MODULE_LICENSE("GPL v2"); 367 MODULE_AUTHOR("Miguel Ojeda <ojeda@kernel.org>"); 368 MODULE_DESCRIPTION("cfag12864b LCD driver"); 369