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 }; 102 103 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 104 return 0; 105 } 106 107 static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y) 108 { 109 struct lcd2s_data *lcd2s = lcd->drvdata; 110 u8 buf[3] = { LCD2S_CMD_CUR_POS, y + 1, x + 1 }; 111 112 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 113 114 return 0; 115 } 116 117 static int lcd2s_home(struct charlcd *lcd) 118 { 119 struct lcd2s_data *lcd2s = lcd->drvdata; 120 121 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET); 122 return 0; 123 } 124 125 static int lcd2s_init_display(struct charlcd *lcd) 126 { 127 struct lcd2s_data *lcd2s = lcd->drvdata; 128 129 /* turn everything off, but display on */ 130 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 131 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 132 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD); 133 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 134 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 135 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 136 137 return 0; 138 } 139 140 static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir) 141 { 142 struct lcd2s_data *lcd2s = lcd->drvdata; 143 144 if (dir == CHARLCD_SHIFT_LEFT) 145 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT); 146 else 147 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT); 148 149 return 0; 150 } 151 152 static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir) 153 { 154 struct lcd2s_data *lcd2s = lcd->drvdata; 155 156 if (dir == CHARLCD_SHIFT_LEFT) 157 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT); 158 else 159 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT); 160 161 return 0; 162 } 163 164 static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on) 165 { 166 struct lcd2s_data *lcd2s = lcd->drvdata; 167 168 if (on) 169 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON); 170 else 171 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 172 } 173 174 static int lcd2s_display(struct charlcd *lcd, enum charlcd_onoff on) 175 { 176 struct lcd2s_data *lcd2s = lcd->drvdata; 177 178 if (on) 179 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 180 else 181 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF); 182 183 return 0; 184 } 185 186 static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on) 187 { 188 struct lcd2s_data *lcd2s = lcd->drvdata; 189 190 if (on) 191 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON); 192 else 193 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 194 195 return 0; 196 } 197 198 static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on) 199 { 200 struct lcd2s_data *lcd2s = lcd->drvdata; 201 202 if (on) 203 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON); 204 else 205 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 206 207 return 0; 208 } 209 210 static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size) 211 { 212 return 0; 213 } 214 215 static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines) 216 { 217 return 0; 218 } 219 220 /* 221 * Generator: LGcxxxxx...xx; must have <c> between '0' and '7', 222 * representing the numerical ASCII code of the redefined character, 223 * and <xx...xx> a sequence of 16 hex digits representing 8 bytes 224 * for each character. Most LCDs will only use 5 lower bits of 225 * the 7 first bytes. 226 */ 227 static int lcd2s_redefine_char(struct charlcd *lcd, char *esc) 228 { 229 struct lcd2s_data *lcd2s = lcd->drvdata; 230 u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR }; 231 u8 value; 232 int shift, i; 233 234 if (!strchr(esc, ';')) 235 return 0; 236 237 esc++; 238 239 buf[1] = *(esc++) - '0'; 240 if (buf[1] > 7) 241 return 1; 242 243 i = 2; 244 shift = 0; 245 value = 0; 246 while (*esc && i < LCD2S_CHARACTER_SIZE + 2) { 247 int half; 248 249 shift ^= 4; 250 half = hex_to_bin(*esc++); 251 if (half < 0) 252 continue; 253 254 value |= half << shift; 255 if (shift == 0) { 256 buf[i++] = value; 257 value = 0; 258 } 259 } 260 261 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 262 return 1; 263 } 264 265 static int lcd2s_clear_display(struct charlcd *lcd) 266 { 267 struct lcd2s_data *lcd2s = lcd->drvdata; 268 269 /* This implicitly sets cursor to first row and column */ 270 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 271 return 0; 272 } 273 274 static const struct charlcd_ops lcd2s_ops = { 275 .print = lcd2s_print, 276 .backlight = lcd2s_backlight, 277 .gotoxy = lcd2s_gotoxy, 278 .home = lcd2s_home, 279 .clear_display = lcd2s_clear_display, 280 .init_display = lcd2s_init_display, 281 .shift_cursor = lcd2s_shift_cursor, 282 .shift_display = lcd2s_shift_display, 283 .display = lcd2s_display, 284 .cursor = lcd2s_cursor, 285 .blink = lcd2s_blink, 286 .fontsize = lcd2s_fontsize, 287 .lines = lcd2s_lines, 288 .redefine_char = lcd2s_redefine_char, 289 }; 290 291 static int lcd2s_i2c_probe(struct i2c_client *i2c) 292 { 293 struct charlcd *lcd; 294 struct lcd2s_data *lcd2s; 295 int err; 296 297 if (!i2c_check_functionality(i2c->adapter, 298 I2C_FUNC_SMBUS_WRITE_BYTE_DATA | 299 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)) 300 return -EIO; 301 302 /* Test, if the display is responding */ 303 err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF); 304 if (err < 0) 305 return err; 306 307 lcd = charlcd_alloc(sizeof(*lcd2s)); 308 if (!lcd) 309 return -ENOMEM; 310 311 lcd->ops = &lcd2s_ops; 312 313 lcd2s = lcd->drvdata; 314 lcd2s->i2c = i2c; 315 lcd2s->charlcd = lcd; 316 317 /* Required properties */ 318 err = device_property_read_u32(&i2c->dev, "display-height-chars", 319 &lcd->height); 320 if (err) 321 goto fail1; 322 323 err = device_property_read_u32(&i2c->dev, "display-width-chars", 324 &lcd->width); 325 if (err) 326 goto fail1; 327 328 err = charlcd_register(lcd2s->charlcd); 329 if (err) 330 goto fail1; 331 332 i2c_set_clientdata(i2c, lcd2s); 333 return 0; 334 335 fail1: 336 charlcd_free(lcd2s->charlcd); 337 return err; 338 } 339 340 static void lcd2s_i2c_remove(struct i2c_client *i2c) 341 { 342 struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c); 343 344 charlcd_unregister(lcd2s->charlcd); 345 charlcd_free(lcd2s->charlcd); 346 } 347 348 static const struct i2c_device_id lcd2s_i2c_id[] = { 349 { "lcd2s" }, 350 { } 351 }; 352 MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id); 353 354 static const struct of_device_id lcd2s_of_table[] = { 355 { .compatible = "modtronix,lcd2s" }, 356 { } 357 }; 358 MODULE_DEVICE_TABLE(of, lcd2s_of_table); 359 360 static struct i2c_driver lcd2s_i2c_driver = { 361 .driver = { 362 .name = "lcd2s", 363 .of_match_table = lcd2s_of_table, 364 }, 365 .probe = lcd2s_i2c_probe, 366 .remove = lcd2s_i2c_remove, 367 .id_table = lcd2s_i2c_id, 368 }; 369 module_i2c_driver(lcd2s_i2c_driver); 370 371 MODULE_DESCRIPTION("LCD2S character display driver"); 372 MODULE_AUTHOR("Lars Poeschel"); 373 MODULE_LICENSE("GPL"); 374