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/mod_devicetable.h> 16 #include <linux/module.h> 17 #include <linux/property.h> 18 #include <linux/slab.h> 19 #include <linux/i2c.h> 20 #include <linux/delay.h> 21 22 #include "charlcd.h" 23 24 #define LCD2S_CMD_CUR_MOVES_FWD 0x09 25 #define LCD2S_CMD_CUR_BLINK_OFF 0x10 26 #define LCD2S_CMD_CUR_UL_OFF 0x11 27 #define LCD2S_CMD_DISPLAY_OFF 0x12 28 #define LCD2S_CMD_CUR_BLINK_ON 0x18 29 #define LCD2S_CMD_CUR_UL_ON 0x19 30 #define LCD2S_CMD_DISPLAY_ON 0x1a 31 #define LCD2S_CMD_BACKLIGHT_OFF 0x20 32 #define LCD2S_CMD_BACKLIGHT_ON 0x28 33 #define LCD2S_CMD_WRITE 0x80 34 #define LCD2S_CMD_MOV_CUR_RIGHT 0x83 35 #define LCD2S_CMD_MOV_CUR_LEFT 0x84 36 #define LCD2S_CMD_SHIFT_RIGHT 0x85 37 #define LCD2S_CMD_SHIFT_LEFT 0x86 38 #define LCD2S_CMD_SHIFT_UP 0x87 39 #define LCD2S_CMD_SHIFT_DOWN 0x88 40 #define LCD2S_CMD_CUR_ADDR 0x89 41 #define LCD2S_CMD_CUR_POS 0x8a 42 #define LCD2S_CMD_CUR_RESET 0x8b 43 #define LCD2S_CMD_CLEAR 0x8c 44 #define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92 45 #define LCD2S_CMD_READ_STATUS 0xd0 46 47 #define LCD2S_CHARACTER_SIZE 8 48 49 #define LCD2S_STATUS_BUF_MASK 0x7f 50 51 struct lcd2s_data { 52 struct i2c_client *i2c; 53 struct charlcd *charlcd; 54 }; 55 56 static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count) 57 { 58 s32 status; 59 60 status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS); 61 if (status < 0) 62 return status; 63 64 while ((status & LCD2S_STATUS_BUF_MASK) < count) { 65 mdelay(1); 66 status = i2c_smbus_read_byte_data(client, 67 LCD2S_CMD_READ_STATUS); 68 if (status < 0) 69 return status; 70 } 71 return 0; 72 } 73 74 static int lcd2s_i2c_master_send(const struct i2c_client *client, 75 const char *buf, int count) 76 { 77 s32 status; 78 79 status = lcd2s_wait_buf_free(client, count); 80 if (status < 0) 81 return status; 82 83 return i2c_master_send(client, buf, count); 84 } 85 86 static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value) 87 { 88 s32 status; 89 90 status = lcd2s_wait_buf_free(client, 1); 91 if (status < 0) 92 return status; 93 94 return i2c_smbus_write_byte(client, value); 95 } 96 97 static int lcd2s_print(struct charlcd *lcd, int c) 98 { 99 struct lcd2s_data *lcd2s = lcd->drvdata; 100 u8 buf[2] = { LCD2S_CMD_WRITE, c }; 101 102 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 103 return 0; 104 } 105 106 static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y) 107 { 108 struct lcd2s_data *lcd2s = lcd->drvdata; 109 u8 buf[3] = { LCD2S_CMD_CUR_POS, y + 1, x + 1 }; 110 111 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 112 113 return 0; 114 } 115 116 static int lcd2s_home(struct charlcd *lcd) 117 { 118 struct lcd2s_data *lcd2s = lcd->drvdata; 119 120 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET); 121 return 0; 122 } 123 124 static int lcd2s_init_display(struct charlcd *lcd) 125 { 126 struct lcd2s_data *lcd2s = lcd->drvdata; 127 128 /* turn everything off, but display on */ 129 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON); 130 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 131 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD); 132 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 133 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 134 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 135 136 return 0; 137 } 138 139 static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir) 140 { 141 struct lcd2s_data *lcd2s = lcd->drvdata; 142 143 if (dir == CHARLCD_SHIFT_LEFT) 144 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT); 145 else 146 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT); 147 148 return 0; 149 } 150 151 static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir) 152 { 153 struct lcd2s_data *lcd2s = lcd->drvdata; 154 155 if (dir == CHARLCD_SHIFT_LEFT) 156 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT); 157 else 158 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT); 159 160 return 0; 161 } 162 163 static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on) 164 { 165 struct lcd2s_data *lcd2s = lcd->drvdata; 166 167 if (on) 168 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON); 169 else 170 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF); 171 } 172 173 static int lcd2s_display(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_DISPLAY_ON); 179 else 180 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF); 181 182 return 0; 183 } 184 185 static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on) 186 { 187 struct lcd2s_data *lcd2s = lcd->drvdata; 188 189 if (on) 190 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON); 191 else 192 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF); 193 194 return 0; 195 } 196 197 static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on) 198 { 199 struct lcd2s_data *lcd2s = lcd->drvdata; 200 201 if (on) 202 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON); 203 else 204 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF); 205 206 return 0; 207 } 208 209 static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size) 210 { 211 return 0; 212 } 213 214 static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines) 215 { 216 return 0; 217 } 218 219 /* 220 * Generator: LGcxxxxx...xx; must have <c> between '0' and '7', 221 * representing the numerical ASCII code of the redefined character, 222 * and <xx...xx> a sequence of 16 hex digits representing 8 bytes 223 * for each character. Most LCDs will only use 5 lower bits of 224 * the 7 first bytes. 225 */ 226 static int lcd2s_redefine_char(struct charlcd *lcd, char *esc) 227 { 228 struct lcd2s_data *lcd2s = lcd->drvdata; 229 u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR }; 230 u8 value; 231 int shift, i; 232 233 if (!strchr(esc, ';')) 234 return 0; 235 236 esc++; 237 238 buf[1] = *(esc++) - '0'; 239 if (buf[1] > 7) 240 return 1; 241 242 i = 2; 243 shift = 0; 244 value = 0; 245 while (*esc && i < LCD2S_CHARACTER_SIZE + 2) { 246 int half; 247 248 shift ^= 4; 249 half = hex_to_bin(*esc++); 250 if (half < 0) 251 continue; 252 253 value |= half << shift; 254 if (shift == 0) { 255 buf[i++] = value; 256 value = 0; 257 } 258 } 259 260 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf)); 261 return 1; 262 } 263 264 static int lcd2s_clear_display(struct charlcd *lcd) 265 { 266 struct lcd2s_data *lcd2s = lcd->drvdata; 267 268 /* This implicitly sets cursor to first row and column */ 269 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR); 270 return 0; 271 } 272 273 static const struct charlcd_ops lcd2s_ops = { 274 .print = lcd2s_print, 275 .backlight = lcd2s_backlight, 276 .gotoxy = lcd2s_gotoxy, 277 .home = lcd2s_home, 278 .clear_display = lcd2s_clear_display, 279 .init_display = lcd2s_init_display, 280 .shift_cursor = lcd2s_shift_cursor, 281 .shift_display = lcd2s_shift_display, 282 .display = lcd2s_display, 283 .cursor = lcd2s_cursor, 284 .blink = lcd2s_blink, 285 .fontsize = lcd2s_fontsize, 286 .lines = lcd2s_lines, 287 .redefine_char = lcd2s_redefine_char, 288 }; 289 290 static int lcd2s_i2c_probe(struct i2c_client *i2c) 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 lcd2s = devm_kzalloc(&i2c->dev, sizeof(*lcd2s), GFP_KERNEL); 302 if (!lcd2s) 303 return -ENOMEM; 304 305 /* Test, if the display is responding */ 306 err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF); 307 if (err < 0) 308 return err; 309 310 lcd = charlcd_alloc(); 311 if (!lcd) 312 return -ENOMEM; 313 314 lcd->drvdata = lcd2s; 315 lcd2s->i2c = i2c; 316 lcd2s->charlcd = lcd; 317 318 /* Required properties */ 319 err = device_property_read_u32(&i2c->dev, "display-height-chars", 320 &lcd->height); 321 if (err) 322 goto fail1; 323 324 err = device_property_read_u32(&i2c->dev, "display-width-chars", 325 &lcd->width); 326 if (err) 327 goto fail1; 328 329 lcd->ops = &lcd2s_ops; 330 331 err = charlcd_register(lcd2s->charlcd); 332 if (err) 333 goto fail1; 334 335 i2c_set_clientdata(i2c, lcd2s); 336 return 0; 337 338 fail1: 339 charlcd_free(lcd2s->charlcd); 340 return err; 341 } 342 343 static void lcd2s_i2c_remove(struct i2c_client *i2c) 344 { 345 struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c); 346 347 charlcd_unregister(lcd2s->charlcd); 348 charlcd_free(lcd2s->charlcd); 349 } 350 351 static const struct i2c_device_id lcd2s_i2c_id[] = { 352 { "lcd2s", 0 }, 353 { } 354 }; 355 MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id); 356 357 static const struct of_device_id lcd2s_of_table[] = { 358 { .compatible = "modtronix,lcd2s" }, 359 { } 360 }; 361 MODULE_DEVICE_TABLE(of, lcd2s_of_table); 362 363 static struct i2c_driver lcd2s_i2c_driver = { 364 .driver = { 365 .name = "lcd2s", 366 .of_match_table = lcd2s_of_table, 367 }, 368 .probe = lcd2s_i2c_probe, 369 .remove = lcd2s_i2c_remove, 370 .id_table = lcd2s_i2c_id, 371 }; 372 module_i2c_driver(lcd2s_i2c_driver); 373 374 MODULE_DESCRIPTION("LCD2S character display driver"); 375 MODULE_AUTHOR("Lars Poeschel"); 376 MODULE_LICENSE("GPL"); 377