1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * console driver for LCD2S 4x20 character displays connected through i2c. 4 * The display also has a spi interface, but the driver does not support 5 * this yet. 6 * 7 * This is a driver allowing you to use a LCD2S 4x20 from modtronix 8 * engineering as auxdisplay character device. 9 * 10 * (C) 2019 by Lemonage Software GmbH 11 * Author: Lars Pöschel <poeschel@lemonage.de> 12 * All rights reserved. 13 */ 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/slab.h> 17 #include <linux/i2c.h> 18 #include <linux/delay.h> 19 20 #include "charlcd.h" 21 22 #define LCD2S_CMD_CUR_MOVES_FWD 0x09 23 #define LCD2S_CMD_CUR_BLINK_OFF 0x10 24 #define LCD2S_CMD_CUR_UL_OFF 0x11 25 #define LCD2S_CMD_DISPLAY_OFF 0x12 26 #define LCD2S_CMD_CUR_BLINK_ON 0x18 27 #define LCD2S_CMD_CUR_UL_ON 0x19 28 #define LCD2S_CMD_DISPLAY_ON 0x1a 29 #define LCD2S_CMD_BACKLIGHT_OFF 0x20 30 #define LCD2S_CMD_BACKLIGHT_ON 0x28 31 #define LCD2S_CMD_WRITE 0x80 32 #define LCD2S_CMD_MOV_CUR_RIGHT 0x83 33 #define LCD2S_CMD_MOV_CUR_LEFT 0x84 34 #define LCD2S_CMD_SHIFT_RIGHT 0x85 35 #define LCD2S_CMD_SHIFT_LEFT 0x86 36 #define LCD2S_CMD_SHIFT_UP 0x87 37 #define LCD2S_CMD_SHIFT_DOWN 0x88 38 #define LCD2S_CMD_CUR_ADDR 0x89 39 #define LCD2S_CMD_CUR_POS 0x8a 40 #define LCD2S_CMD_CUR_RESET 0x8b 41 #define LCD2S_CMD_CLEAR 0x8c 42 #define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92 43 #define LCD2S_CMD_READ_STATUS 0xd0 44 45 #define LCD2S_CHARACTER_SIZE 8 46 47 #define LCD2S_STATUS_BUF_MASK 0x7f 48 49 struct lcd2s_data { 50 struct i2c_client *i2c; 51 struct charlcd *charlcd; 52 }; 53 54 static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count) 55 { 56 s32 status; 57 58 status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS); 59 if (status < 0) 60 return status; 61 62 while ((status & LCD2S_STATUS_BUF_MASK) < count) { 63 mdelay(1); 64 status = i2c_smbus_read_byte_data(client, 65 LCD2S_CMD_READ_STATUS); 66 if (status < 0) 67 return status; 68 } 69 return 0; 70 } 71 72 static int lcd2s_i2c_master_send(const struct i2c_client *client, 73 const char *buf, int count) 74 { 75 s32 status; 76 77 status = lcd2s_wait_buf_free(client, count); 78 if (status < 0) 79 return status; 80 81 return i2c_master_send(client, buf, count); 82 } 83 84 static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value) 85 { 86 s32 status; 87 88 status = lcd2s_wait_buf_free(client, 1); 89 if (status < 0) 90 return status; 91 92 return i2c_smbus_write_byte(client, value); 93 } 94 95 static int lcd2s_print(struct charlcd *lcd, int c) 96 { 97 struct lcd2s_data *lcd2s = lcd->drvdata; 98 u8 buf[2] = { LCD2S_CMD_WRITE, c }; 99 100 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 101 return 0; 102 } 103 104 static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y) 105 { 106 struct lcd2s_data *lcd2s = lcd->drvdata; 107 u8 buf[] = { LCD2S_CMD_CUR_POS, y + 1, x + 1}; 108 109 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 110 111 return 0; 112 } 113 114 static int lcd2s_home(struct charlcd *lcd) 115 { 116 struct lcd2s_data *lcd2s = lcd->drvdata; 117 118 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET); 119 return 0; 120 } 121 122 static int lcd2s_init_display(struct charlcd *lcd) 123 { 124 struct lcd2s_data *lcd2s = lcd->drvdata; 125 126 /* turn everything off, but display on */ 127 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 128 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 129 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD); 130 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 131 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 132 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 133 134 return 0; 135 } 136 137 static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir) 138 { 139 struct lcd2s_data *lcd2s = lcd->drvdata; 140 141 if (dir == CHARLCD_SHIFT_LEFT) 142 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT); 143 else 144 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT); 145 146 return 0; 147 } 148 149 static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir) 150 { 151 struct lcd2s_data *lcd2s = lcd->drvdata; 152 153 if (dir == CHARLCD_SHIFT_LEFT) 154 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT); 155 else 156 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT); 157 158 return 0; 159 } 160 161 static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on) 162 { 163 struct lcd2s_data *lcd2s = lcd->drvdata; 164 165 if (on) 166 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON); 167 else 168 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 169 } 170 171 static int lcd2s_display(struct charlcd *lcd, enum charlcd_onoff on) 172 { 173 struct lcd2s_data *lcd2s = lcd->drvdata; 174 175 if (on) 176 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 177 else 178 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF); 179 180 return 0; 181 } 182 183 static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on) 184 { 185 struct lcd2s_data *lcd2s = lcd->drvdata; 186 187 if (on) 188 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON); 189 else 190 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 191 192 return 0; 193 } 194 195 static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on) 196 { 197 struct lcd2s_data *lcd2s = lcd->drvdata; 198 199 if (on) 200 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON); 201 else 202 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 203 204 return 0; 205 } 206 207 static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size) 208 { 209 return 0; 210 } 211 212 static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines) 213 { 214 return 0; 215 } 216 217 static int lcd2s_redefine_char(struct charlcd *lcd, char *esc) 218 { 219 /* Generator : LGcxxxxx...xx; must have <c> between '0' 220 * and '7', representing the numerical ASCII code of the 221 * redefined character, and <xx...xx> a sequence of 16 222 * hex digits representing 8 bytes for each character. 223 * Most LCDs will only use 5 lower bits of the 7 first 224 * bytes. 225 */ 226 227 struct lcd2s_data *lcd2s = lcd->drvdata; 228 u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR }; 229 u8 value; 230 int shift, i; 231 232 if (!strchr(esc, ';')) 233 return 0; 234 235 esc++; 236 237 buf[1] = *(esc++) - '0'; 238 if (buf[1] > 7) 239 return 1; 240 241 i = 0; 242 shift = 0; 243 value = 0; 244 while (*esc && i < LCD2S_CHARACTER_SIZE + 2) { 245 int half; 246 247 shift ^= 4; 248 half = hex_to_bin(*esc++); 249 if (half < 0) 250 continue; 251 252 value |= half << shift; 253 if (shift == 0) { 254 buf[i++] = value; 255 value = 0; 256 } 257 } 258 259 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 260 return 1; 261 } 262 263 static int lcd2s_clear_display(struct charlcd *lcd) 264 { 265 struct lcd2s_data *lcd2s = lcd->drvdata; 266 267 /* This implicitly sets cursor to first row and column */ 268 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 269 return 0; 270 } 271 272 static const struct charlcd_ops lcd2s_ops = { 273 .print = lcd2s_print, 274 .backlight = lcd2s_backlight, 275 .gotoxy = lcd2s_gotoxy, 276 .home = lcd2s_home, 277 .clear_display = lcd2s_clear_display, 278 .init_display = lcd2s_init_display, 279 .shift_cursor = lcd2s_shift_cursor, 280 .shift_display = lcd2s_shift_display, 281 .display = lcd2s_display, 282 .cursor = lcd2s_cursor, 283 .blink = lcd2s_blink, 284 .fontsize = lcd2s_fontsize, 285 .lines = lcd2s_lines, 286 .redefine_char = lcd2s_redefine_char, 287 }; 288 289 static int lcd2s_i2c_probe(struct i2c_client *i2c, 290 const struct i2c_device_id *id) 291 { 292 struct charlcd *lcd; 293 struct lcd2s_data *lcd2s; 294 int err; 295 296 if (!i2c_check_functionality(i2c->adapter, 297 I2C_FUNC_SMBUS_WRITE_BYTE_DATA | 298 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)) 299 return -EIO; 300 301 /* Test, if the display is responding */ 302 err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF); 303 if (err < 0) 304 return err; 305 306 lcd = charlcd_alloc(); 307 if (!lcd) 308 return -ENOMEM; 309 310 lcd2s = kzalloc(sizeof(struct lcd2s_data), GFP_KERNEL); 311 if (!lcd2s) { 312 err = -ENOMEM; 313 goto fail1; 314 } 315 316 lcd->drvdata = lcd2s; 317 lcd2s->i2c = i2c; 318 lcd2s->charlcd = lcd; 319 320 /* Required properties */ 321 err = device_property_read_u32(&i2c->dev, "display-height-chars", 322 &lcd->height); 323 if (err) 324 goto fail2; 325 326 err = device_property_read_u32(&i2c->dev, "display-width-chars", 327 &lcd->width); 328 if (err) 329 goto fail2; 330 331 lcd->ops = &lcd2s_ops; 332 333 err = charlcd_register(lcd2s->charlcd); 334 if (err) 335 goto fail2; 336 337 i2c_set_clientdata(i2c, lcd2s); 338 return 0; 339 340 fail2: 341 kfree(lcd2s); 342 fail1: 343 kfree(lcd); 344 return err; 345 } 346 347 static int lcd2s_i2c_remove(struct i2c_client *i2c) 348 { 349 struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c); 350 351 charlcd_unregister(lcd2s->charlcd); 352 kfree(lcd2s->charlcd); 353 return 0; 354 } 355 356 static const struct i2c_device_id lcd2s_i2c_id[] = { 357 { "lcd2s", 0 }, 358 { } 359 }; 360 MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id); 361 362 #ifdef CONFIG_OF 363 static const struct of_device_id lcd2s_of_table[] = { 364 { .compatible = "modtronix,lcd2s" }, 365 { } 366 }; 367 MODULE_DEVICE_TABLE(of, lcd2s_of_table); 368 #endif 369 370 static struct i2c_driver lcd2s_i2c_driver = { 371 .driver = { 372 .name = "lcd2s", 373 #ifdef CONFIG_OF 374 .of_match_table = of_match_ptr(lcd2s_of_table), 375 #endif 376 }, 377 .probe = lcd2s_i2c_probe, 378 .remove = lcd2s_i2c_remove, 379 .id_table = lcd2s_i2c_id, 380 }; 381 382 static int __init lcd2s_modinit(void) 383 { 384 int ret = 0; 385 386 ret = i2c_add_driver(&lcd2s_i2c_driver); 387 if (ret != 0) 388 pr_err("Failed to register lcd2s driver\n"); 389 390 return ret; 391 } 392 module_init(lcd2s_modinit) 393 394 static void __exit lcd2s_exit(void) 395 { 396 i2c_del_driver(&lcd2s_i2c_driver); 397 } 398 module_exit(lcd2s_exit) 399 400 MODULE_DESCRIPTION("LCD2S character display driver"); 401 MODULE_AUTHOR("Lars Poeschel"); 402 MODULE_LICENSE("GPL"); 403