1 /* 2 * Copyright (C) 2016 Imagination Technologies 3 * Author: Paul Burton <paul.burton@imgtec.com> 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License as published by the 7 * Free Software Foundation; either version 2 of the License, or (at your 8 * option) any later version. 9 */ 10 11 #include <generated/utsrelease.h> 12 #include <linux/kernel.h> 13 #include <linux/io.h> 14 #include <linux/mfd/syscon.h> 15 #include <linux/module.h> 16 #include <linux/of_address.h> 17 #include <linux/of_platform.h> 18 #include <linux/platform_device.h> 19 #include <linux/regmap.h> 20 #include <linux/slab.h> 21 #include <linux/sysfs.h> 22 23 struct img_ascii_lcd_ctx; 24 25 /** 26 * struct img_ascii_lcd_config - Configuration information about an LCD model 27 * @num_chars: the number of characters the LCD can display 28 * @external_regmap: true if registers are in a system controller, else false 29 * @update: function called to update the LCD 30 */ 31 struct img_ascii_lcd_config { 32 unsigned int num_chars; 33 bool external_regmap; 34 void (*update)(struct img_ascii_lcd_ctx *ctx); 35 }; 36 37 /** 38 * struct img_ascii_lcd_ctx - Private data structure 39 * @pdev: the ASCII LCD platform device 40 * @base: the base address of the LCD registers 41 * @regmap: the regmap through which LCD registers are accessed 42 * @offset: the offset within regmap to the start of the LCD registers 43 * @cfg: pointer to the LCD model configuration 44 * @message: the full message to display or scroll on the LCD 45 * @message_len: the length of the @message string 46 * @scroll_pos: index of the first character of @message currently displayed 47 * @scroll_rate: scroll interval in jiffies 48 * @timer: timer used to implement scrolling 49 * @curr: the string currently displayed on the LCD 50 */ 51 struct img_ascii_lcd_ctx { 52 struct platform_device *pdev; 53 union { 54 void __iomem *base; 55 struct regmap *regmap; 56 }; 57 u32 offset; 58 const struct img_ascii_lcd_config *cfg; 59 char *message; 60 unsigned int message_len; 61 unsigned int scroll_pos; 62 unsigned int scroll_rate; 63 struct timer_list timer; 64 char curr[] __aligned(8); 65 }; 66 67 /* 68 * MIPS Boston development board 69 */ 70 71 static void boston_update(struct img_ascii_lcd_ctx *ctx) 72 { 73 ulong val; 74 75 #if BITS_PER_LONG == 64 76 val = *((u64 *)&ctx->curr[0]); 77 __raw_writeq(val, ctx->base); 78 #elif BITS_PER_LONG == 32 79 val = *((u32 *)&ctx->curr[0]); 80 __raw_writel(val, ctx->base); 81 val = *((u32 *)&ctx->curr[4]); 82 __raw_writel(val, ctx->base + 4); 83 #else 84 # error Not 32 or 64 bit 85 #endif 86 } 87 88 static struct img_ascii_lcd_config boston_config = { 89 .num_chars = 8, 90 .update = boston_update, 91 }; 92 93 /* 94 * MIPS Malta development board 95 */ 96 97 static void malta_update(struct img_ascii_lcd_ctx *ctx) 98 { 99 unsigned int i; 100 int err; 101 102 for (i = 0; i < ctx->cfg->num_chars; i++) { 103 err = regmap_write(ctx->regmap, 104 ctx->offset + (i * 8), ctx->curr[i]); 105 if (err) 106 break; 107 } 108 109 if (unlikely(err)) 110 pr_err_ratelimited("Failed to update LCD display: %d\n", err); 111 } 112 113 static struct img_ascii_lcd_config malta_config = { 114 .num_chars = 8, 115 .external_regmap = true, 116 .update = malta_update, 117 }; 118 119 /* 120 * MIPS SEAD3 development board 121 */ 122 123 enum { 124 SEAD3_REG_LCD_CTRL = 0x00, 125 #define SEAD3_REG_LCD_CTRL_SETDRAM BIT(7) 126 SEAD3_REG_LCD_DATA = 0x08, 127 SEAD3_REG_CPLD_STATUS = 0x10, 128 #define SEAD3_REG_CPLD_STATUS_BUSY BIT(0) 129 SEAD3_REG_CPLD_DATA = 0x18, 130 #define SEAD3_REG_CPLD_DATA_BUSY BIT(7) 131 }; 132 133 static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx) 134 { 135 unsigned int status; 136 int err; 137 138 do { 139 err = regmap_read(ctx->regmap, 140 ctx->offset + SEAD3_REG_CPLD_STATUS, 141 &status); 142 if (err) 143 return err; 144 } while (status & SEAD3_REG_CPLD_STATUS_BUSY); 145 146 return 0; 147 148 } 149 150 static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx) 151 { 152 unsigned int cpld_data; 153 int err; 154 155 err = sead3_wait_sm_idle(ctx); 156 if (err) 157 return err; 158 159 do { 160 err = regmap_read(ctx->regmap, 161 ctx->offset + SEAD3_REG_LCD_CTRL, 162 &cpld_data); 163 if (err) 164 return err; 165 166 err = sead3_wait_sm_idle(ctx); 167 if (err) 168 return err; 169 170 err = regmap_read(ctx->regmap, 171 ctx->offset + SEAD3_REG_CPLD_DATA, 172 &cpld_data); 173 if (err) 174 return err; 175 } while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY); 176 177 return 0; 178 } 179 180 static void sead3_update(struct img_ascii_lcd_ctx *ctx) 181 { 182 unsigned int i; 183 int err; 184 185 for (i = 0; i < ctx->cfg->num_chars; i++) { 186 err = sead3_wait_lcd_idle(ctx); 187 if (err) 188 break; 189 190 err = regmap_write(ctx->regmap, 191 ctx->offset + SEAD3_REG_LCD_CTRL, 192 SEAD3_REG_LCD_CTRL_SETDRAM | i); 193 if (err) 194 break; 195 196 err = sead3_wait_lcd_idle(ctx); 197 if (err) 198 break; 199 200 err = regmap_write(ctx->regmap, 201 ctx->offset + SEAD3_REG_LCD_DATA, 202 ctx->curr[i]); 203 if (err) 204 break; 205 } 206 207 if (unlikely(err)) 208 pr_err_ratelimited("Failed to update LCD display: %d\n", err); 209 } 210 211 static struct img_ascii_lcd_config sead3_config = { 212 .num_chars = 16, 213 .external_regmap = true, 214 .update = sead3_update, 215 }; 216 217 static const struct of_device_id img_ascii_lcd_matches[] = { 218 { .compatible = "img,boston-lcd", .data = &boston_config }, 219 { .compatible = "mti,malta-lcd", .data = &malta_config }, 220 { .compatible = "mti,sead3-lcd", .data = &sead3_config }, 221 { /* sentinel */ } 222 }; 223 MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches); 224 225 /** 226 * img_ascii_lcd_scroll() - scroll the display by a character 227 * @arg: really a pointer to the private data structure 228 * 229 * Scroll the current message along the LCD by one character, rearming the 230 * timer if required. 231 */ 232 static void img_ascii_lcd_scroll(unsigned long arg) 233 { 234 struct img_ascii_lcd_ctx *ctx = (struct img_ascii_lcd_ctx *)arg; 235 unsigned int i, ch = ctx->scroll_pos; 236 unsigned int num_chars = ctx->cfg->num_chars; 237 238 /* update the current message string */ 239 for (i = 0; i < num_chars;) { 240 /* copy as many characters from the string as possible */ 241 for (; i < num_chars && ch < ctx->message_len; i++, ch++) 242 ctx->curr[i] = ctx->message[ch]; 243 244 /* wrap around to the start of the string */ 245 ch = 0; 246 } 247 248 /* update the LCD */ 249 ctx->cfg->update(ctx); 250 251 /* move on to the next character */ 252 ctx->scroll_pos++; 253 ctx->scroll_pos %= ctx->message_len; 254 255 /* rearm the timer */ 256 if (ctx->message_len > ctx->cfg->num_chars) 257 mod_timer(&ctx->timer, jiffies + ctx->scroll_rate); 258 } 259 260 /** 261 * img_ascii_lcd_display() - set the message to be displayed 262 * @ctx: pointer to the private data structure 263 * @msg: the message to display 264 * @count: length of msg, or -1 265 * 266 * Display a new message @msg on the LCD. @msg can be longer than the number of 267 * characters the LCD can display, in which case it will begin scrolling across 268 * the LCD display. 269 * 270 * Return: 0 on success, -ENOMEM on memory allocation failure 271 */ 272 static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx, 273 const char *msg, ssize_t count) 274 { 275 char *new_msg; 276 277 /* stop the scroll timer */ 278 del_timer_sync(&ctx->timer); 279 280 if (count == -1) 281 count = strlen(msg); 282 283 /* if the string ends with a newline, trim it */ 284 if (msg[count - 1] == '\n') 285 count--; 286 287 new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL); 288 if (!new_msg) 289 return -ENOMEM; 290 291 memcpy(new_msg, msg, count); 292 new_msg[count] = 0; 293 294 if (ctx->message) 295 devm_kfree(&ctx->pdev->dev, ctx->message); 296 297 ctx->message = new_msg; 298 ctx->message_len = count; 299 ctx->scroll_pos = 0; 300 301 /* update the LCD */ 302 img_ascii_lcd_scroll((unsigned long)ctx); 303 304 return 0; 305 } 306 307 /** 308 * message_show() - read message via sysfs 309 * @dev: the LCD device 310 * @attr: the LCD message attribute 311 * @buf: the buffer to read the message into 312 * 313 * Read the current message being displayed or scrolled across the LCD display 314 * into @buf, for reads from sysfs. 315 * 316 * Return: the number of characters written to @buf 317 */ 318 static ssize_t message_show(struct device *dev, struct device_attribute *attr, 319 char *buf) 320 { 321 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 322 323 return sprintf(buf, "%s\n", ctx->message); 324 } 325 326 /** 327 * message_store() - write a new message via sysfs 328 * @dev: the LCD device 329 * @attr: the LCD message attribute 330 * @buf: the buffer containing the new message 331 * @count: the size of the message in @buf 332 * 333 * Write a new message to display or scroll across the LCD display from sysfs. 334 * 335 * Return: the size of the message on success, else -ERRNO 336 */ 337 static ssize_t message_store(struct device *dev, struct device_attribute *attr, 338 const char *buf, size_t count) 339 { 340 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 341 int err; 342 343 err = img_ascii_lcd_display(ctx, buf, count); 344 return err ?: count; 345 } 346 347 static DEVICE_ATTR_RW(message); 348 349 /** 350 * img_ascii_lcd_probe() - probe an LCD display device 351 * @pdev: the LCD platform device 352 * 353 * Probe an LCD display device, ensuring that we have the required resources in 354 * order to access the LCD & setting up private data as well as sysfs files. 355 * 356 * Return: 0 on success, else -ERRNO 357 */ 358 static int img_ascii_lcd_probe(struct platform_device *pdev) 359 { 360 const struct of_device_id *match; 361 const struct img_ascii_lcd_config *cfg; 362 struct img_ascii_lcd_ctx *ctx; 363 struct resource *res; 364 int err; 365 366 match = of_match_device(img_ascii_lcd_matches, &pdev->dev); 367 if (!match) 368 return -ENODEV; 369 370 cfg = match->data; 371 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars, 372 GFP_KERNEL); 373 if (!ctx) 374 return -ENOMEM; 375 376 if (cfg->external_regmap) { 377 ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); 378 if (IS_ERR(ctx->regmap)) 379 return PTR_ERR(ctx->regmap); 380 381 if (of_property_read_u32(pdev->dev.of_node, "offset", 382 &ctx->offset)) 383 return -EINVAL; 384 } else { 385 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 386 ctx->base = devm_ioremap_resource(&pdev->dev, res); 387 if (IS_ERR(ctx->base)) 388 return PTR_ERR(ctx->base); 389 } 390 391 ctx->pdev = pdev; 392 ctx->cfg = cfg; 393 ctx->message = NULL; 394 ctx->scroll_pos = 0; 395 ctx->scroll_rate = HZ / 2; 396 397 /* initialise a timer for scrolling the message */ 398 init_timer(&ctx->timer); 399 ctx->timer.function = img_ascii_lcd_scroll; 400 ctx->timer.data = (unsigned long)ctx; 401 402 platform_set_drvdata(pdev, ctx); 403 404 /* display a default message */ 405 err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1); 406 if (err) 407 goto out_del_timer; 408 409 err = device_create_file(&pdev->dev, &dev_attr_message); 410 if (err) 411 goto out_del_timer; 412 413 return 0; 414 out_del_timer: 415 del_timer_sync(&ctx->timer); 416 return err; 417 } 418 419 /** 420 * img_ascii_lcd_remove() - remove an LCD display device 421 * @pdev: the LCD platform device 422 * 423 * Remove an LCD display device, freeing private resources & ensuring that the 424 * driver stops using the LCD display registers. 425 * 426 * Return: 0 427 */ 428 static int img_ascii_lcd_remove(struct platform_device *pdev) 429 { 430 struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev); 431 432 device_remove_file(&pdev->dev, &dev_attr_message); 433 del_timer_sync(&ctx->timer); 434 return 0; 435 } 436 437 static struct platform_driver img_ascii_lcd_driver = { 438 .driver = { 439 .name = "img-ascii-lcd", 440 .of_match_table = img_ascii_lcd_matches, 441 }, 442 .probe = img_ascii_lcd_probe, 443 .remove = img_ascii_lcd_remove, 444 }; 445 module_platform_driver(img_ascii_lcd_driver); 446