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/hex.h> 15 #include <linux/kernel.h> 16 #include <linux/mod_devicetable.h> 17 #include <linux/module.h> 18 #include <linux/property.h> 19 #include <linux/slab.h> 20 #include <linux/i2c.h> 21 #include <linux/delay.h> 22 23 #include "charlcd.h" 24 25 #define LCD2S_CMD_CUR_MOVES_FWD 0x09 26 #define LCD2S_CMD_CUR_BLINK_OFF 0x10 27 #define LCD2S_CMD_CUR_UL_OFF 0x11 28 #define LCD2S_CMD_DISPLAY_OFF 0x12 29 #define LCD2S_CMD_CUR_BLINK_ON 0x18 30 #define LCD2S_CMD_CUR_UL_ON 0x19 31 #define LCD2S_CMD_DISPLAY_ON 0x1a 32 #define LCD2S_CMD_BACKLIGHT_OFF 0x20 33 #define LCD2S_CMD_BACKLIGHT_ON 0x28 34 #define LCD2S_CMD_WRITE 0x80 35 #define LCD2S_CMD_MOV_CUR_RIGHT 0x83 36 #define LCD2S_CMD_MOV_CUR_LEFT 0x84 37 #define LCD2S_CMD_SHIFT_RIGHT 0x85 38 #define LCD2S_CMD_SHIFT_LEFT 0x86 39 #define LCD2S_CMD_SHIFT_UP 0x87 40 #define LCD2S_CMD_SHIFT_DOWN 0x88 41 #define LCD2S_CMD_CUR_ADDR 0x89 42 #define LCD2S_CMD_CUR_POS 0x8a 43 #define LCD2S_CMD_CUR_RESET 0x8b 44 #define LCD2S_CMD_CLEAR 0x8c 45 #define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92 46 #define LCD2S_CMD_READ_STATUS 0xd0 47 48 #define LCD2S_CHARACTER_SIZE 8 49 50 #define LCD2S_STATUS_BUF_MASK 0x7f 51 52 struct lcd2s_data { 53 struct i2c_client *i2c; 54 struct charlcd *charlcd; 55 }; 56 57 static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count) 58 { 59 s32 status; 60 61 status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS); 62 if (status < 0) 63 return status; 64 65 while ((status & LCD2S_STATUS_BUF_MASK) < count) { 66 mdelay(1); 67 status = i2c_smbus_read_byte_data(client, 68 LCD2S_CMD_READ_STATUS); 69 if (status < 0) 70 return status; 71 } 72 return 0; 73 } 74 75 static int lcd2s_i2c_master_send(const struct i2c_client *client, 76 const char *buf, int count) 77 { 78 s32 status; 79 80 status = lcd2s_wait_buf_free(client, count); 81 if (status < 0) 82 return status; 83 84 return i2c_master_send(client, buf, count); 85 } 86 87 static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value) 88 { 89 s32 status; 90 91 status = lcd2s_wait_buf_free(client, 1); 92 if (status < 0) 93 return status; 94 95 return i2c_smbus_write_byte(client, value); 96 } 97 98 static int lcd2s_print(struct charlcd *lcd, int c) 99 { 100 struct lcd2s_data *lcd2s = lcd->drvdata; 101 u8 buf[2] = { LCD2S_CMD_WRITE, c }; 102 int ret; 103 104 ret = lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 105 if (ret < 0) 106 return ret; 107 if (ret != sizeof(buf)) 108 return -EIO; 109 return 0; 110 } 111 112 static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y) 113 { 114 struct lcd2s_data *lcd2s = lcd->drvdata; 115 u8 buf[3] = { LCD2S_CMD_CUR_POS, y + 1, x + 1 }; 116 int ret; 117 118 ret = lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 119 if (ret < 0) 120 return ret; 121 if (ret != sizeof(buf)) 122 return -EIO; 123 return 0; 124 } 125 126 static int lcd2s_home(struct charlcd *lcd) 127 { 128 struct lcd2s_data *lcd2s = lcd->drvdata; 129 130 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET); 131 return 0; 132 } 133 134 static int lcd2s_init_display(struct charlcd *lcd) 135 { 136 struct lcd2s_data *lcd2s = lcd->drvdata; 137 138 /* turn everything off, but display on */ 139 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 140 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 141 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD); 142 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 143 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 144 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 145 146 return 0; 147 } 148 149 static int lcd2s_shift_cursor(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_MOV_CUR_LEFT); 155 else 156 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT); 157 158 return 0; 159 } 160 161 static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir) 162 { 163 struct lcd2s_data *lcd2s = lcd->drvdata; 164 165 if (dir == CHARLCD_SHIFT_LEFT) 166 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT); 167 else 168 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT); 169 170 return 0; 171 } 172 173 static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on) 174 { 175 struct lcd2s_data *lcd2s = lcd->drvdata; 176 177 if (on) 178 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON); 179 else 180 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 181 } 182 183 static int lcd2s_display(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_DISPLAY_ON); 189 else 190 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF); 191 192 return 0; 193 } 194 195 static int lcd2s_cursor(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_UL_ON); 201 else 202 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 203 204 return 0; 205 } 206 207 static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on) 208 { 209 struct lcd2s_data *lcd2s = lcd->drvdata; 210 211 if (on) 212 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON); 213 else 214 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 215 216 return 0; 217 } 218 219 static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size) 220 { 221 return 0; 222 } 223 224 static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines) 225 { 226 return 0; 227 } 228 229 /* 230 * Generator: LGcxxxxx...xx; must have <c> between '0' and '7', 231 * representing the numerical ASCII code of the redefined character, 232 * and <xx...xx> a sequence of 16 hex digits representing 8 bytes 233 * for each character. Most LCDs will only use 5 lower bits of 234 * the 7 first bytes. 235 */ 236 static int lcd2s_redefine_char(struct charlcd *lcd, char *esc) 237 { 238 struct lcd2s_data *lcd2s = lcd->drvdata; 239 u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR }; 240 u8 value; 241 int shift, i; 242 243 if (!strchr(esc, ';')) 244 return 0; 245 246 esc++; 247 248 buf[1] = *(esc++) - '0'; 249 if (buf[1] > 7) 250 return 1; 251 252 i = 2; 253 shift = 0; 254 value = 0; 255 while (*esc && i < LCD2S_CHARACTER_SIZE + 2) { 256 int half; 257 258 shift ^= 4; 259 half = hex_to_bin(*esc++); 260 if (half < 0) 261 continue; 262 263 value |= half << shift; 264 if (shift == 0) { 265 buf[i++] = value; 266 value = 0; 267 } 268 } 269 270 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 271 return 1; 272 } 273 274 static int lcd2s_clear_display(struct charlcd *lcd) 275 { 276 struct lcd2s_data *lcd2s = lcd->drvdata; 277 278 /* This implicitly sets cursor to first row and column */ 279 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 280 return 0; 281 } 282 283 static const struct charlcd_ops lcd2s_ops = { 284 .print = lcd2s_print, 285 .backlight = lcd2s_backlight, 286 .gotoxy = lcd2s_gotoxy, 287 .home = lcd2s_home, 288 .clear_display = lcd2s_clear_display, 289 .init_display = lcd2s_init_display, 290 .shift_cursor = lcd2s_shift_cursor, 291 .shift_display = lcd2s_shift_display, 292 .display = lcd2s_display, 293 .cursor = lcd2s_cursor, 294 .blink = lcd2s_blink, 295 .fontsize = lcd2s_fontsize, 296 .lines = lcd2s_lines, 297 .redefine_char = lcd2s_redefine_char, 298 }; 299 300 static int lcd2s_i2c_probe(struct i2c_client *i2c) 301 { 302 struct charlcd *lcd; 303 struct lcd2s_data *lcd2s; 304 int err; 305 306 if (!i2c_check_functionality(i2c->adapter, 307 I2C_FUNC_SMBUS_WRITE_BYTE_DATA | 308 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)) 309 return -EIO; 310 311 /* Test, if the display is responding */ 312 err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF); 313 if (err < 0) 314 return err; 315 316 lcd = charlcd_alloc(sizeof(*lcd2s)); 317 if (!lcd) 318 return -ENOMEM; 319 320 lcd->ops = &lcd2s_ops; 321 322 lcd2s = lcd->drvdata; 323 lcd2s->i2c = i2c; 324 lcd2s->charlcd = lcd; 325 326 /* Required properties */ 327 err = device_property_read_u32(&i2c->dev, "display-height-chars", 328 &lcd->height); 329 if (err) 330 goto fail1; 331 332 err = device_property_read_u32(&i2c->dev, "display-width-chars", 333 &lcd->width); 334 if (err) 335 goto fail1; 336 337 err = charlcd_register(lcd2s->charlcd); 338 if (err) 339 goto fail1; 340 341 i2c_set_clientdata(i2c, lcd2s); 342 return 0; 343 344 fail1: 345 charlcd_free(lcd2s->charlcd); 346 return err; 347 } 348 349 static void lcd2s_i2c_remove(struct i2c_client *i2c) 350 { 351 struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c); 352 353 charlcd_unregister(lcd2s->charlcd); 354 charlcd_free(lcd2s->charlcd); 355 } 356 357 static const struct i2c_device_id lcd2s_i2c_id[] = { 358 { "lcd2s" }, 359 { } 360 }; 361 MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id); 362 363 static const struct of_device_id lcd2s_of_table[] = { 364 { .compatible = "modtronix,lcd2s" }, 365 { } 366 }; 367 MODULE_DEVICE_TABLE(of, lcd2s_of_table); 368 369 static struct i2c_driver lcd2s_i2c_driver = { 370 .driver = { 371 .name = "lcd2s", 372 .of_match_table = lcd2s_of_table, 373 }, 374 .probe = lcd2s_i2c_probe, 375 .remove = lcd2s_i2c_remove, 376 .id_table = lcd2s_i2c_id, 377 }; 378 module_i2c_driver(lcd2s_i2c_driver); 379 380 MODULE_DESCRIPTION("LCD2S character display driver"); 381 MODULE_AUTHOR("Lars Poeschel"); 382 MODULE_LICENSE("GPL"); 383