1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2016 Imagination Technologies 4 * Author: Paul Burton <paul.burton@mips.com> 5 */ 6 7 #include <generated/utsrelease.h> 8 #include <linux/kernel.h> 9 #include <linux/io.h> 10 #include <linux/mfd/syscon.h> 11 #include <linux/module.h> 12 #include <linux/of_address.h> 13 #include <linux/of_platform.h> 14 #include <linux/platform_device.h> 15 #include <linux/regmap.h> 16 #include <linux/slab.h> 17 #include <linux/sysfs.h> 18 19 struct img_ascii_lcd_ctx; 20 21 /** 22 * struct img_ascii_lcd_config - Configuration information about an LCD model 23 * @num_chars: the number of characters the LCD can display 24 * @external_regmap: true if registers are in a system controller, else false 25 * @update: function called to update the LCD 26 */ 27 struct img_ascii_lcd_config { 28 unsigned int num_chars; 29 bool external_regmap; 30 void (*update)(struct img_ascii_lcd_ctx *ctx); 31 }; 32 33 /** 34 * struct img_ascii_lcd_ctx - Private data structure 35 * @pdev: the ASCII LCD platform device 36 * @base: the base address of the LCD registers 37 * @regmap: the regmap through which LCD registers are accessed 38 * @offset: the offset within regmap to the start of the LCD registers 39 * @cfg: pointer to the LCD model configuration 40 * @message: the full message to display or scroll on the LCD 41 * @message_len: the length of the @message string 42 * @scroll_pos: index of the first character of @message currently displayed 43 * @scroll_rate: scroll interval in jiffies 44 * @timer: timer used to implement scrolling 45 * @curr: the string currently displayed on the LCD 46 */ 47 struct img_ascii_lcd_ctx { 48 struct platform_device *pdev; 49 union { 50 void __iomem *base; 51 struct regmap *regmap; 52 }; 53 u32 offset; 54 const struct img_ascii_lcd_config *cfg; 55 char *message; 56 unsigned int message_len; 57 unsigned int scroll_pos; 58 unsigned int scroll_rate; 59 struct timer_list timer; 60 char curr[] __aligned(8); 61 }; 62 63 /* 64 * MIPS Boston development board 65 */ 66 67 static void boston_update(struct img_ascii_lcd_ctx *ctx) 68 { 69 ulong val; 70 71 #if BITS_PER_LONG == 64 72 val = *((u64 *)&ctx->curr[0]); 73 __raw_writeq(val, ctx->base); 74 #elif BITS_PER_LONG == 32 75 val = *((u32 *)&ctx->curr[0]); 76 __raw_writel(val, ctx->base); 77 val = *((u32 *)&ctx->curr[4]); 78 __raw_writel(val, ctx->base + 4); 79 #else 80 # error Not 32 or 64 bit 81 #endif 82 } 83 84 static struct img_ascii_lcd_config boston_config = { 85 .num_chars = 8, 86 .update = boston_update, 87 }; 88 89 /* 90 * MIPS Malta development board 91 */ 92 93 static void malta_update(struct img_ascii_lcd_ctx *ctx) 94 { 95 unsigned int i; 96 int err = 0; 97 98 for (i = 0; i < ctx->cfg->num_chars; i++) { 99 err = regmap_write(ctx->regmap, 100 ctx->offset + (i * 8), ctx->curr[i]); 101 if (err) 102 break; 103 } 104 105 if (unlikely(err)) 106 pr_err_ratelimited("Failed to update LCD display: %d\n", err); 107 } 108 109 static struct img_ascii_lcd_config malta_config = { 110 .num_chars = 8, 111 .external_regmap = true, 112 .update = malta_update, 113 }; 114 115 /* 116 * MIPS SEAD3 development board 117 */ 118 119 enum { 120 SEAD3_REG_LCD_CTRL = 0x00, 121 #define SEAD3_REG_LCD_CTRL_SETDRAM BIT(7) 122 SEAD3_REG_LCD_DATA = 0x08, 123 SEAD3_REG_CPLD_STATUS = 0x10, 124 #define SEAD3_REG_CPLD_STATUS_BUSY BIT(0) 125 SEAD3_REG_CPLD_DATA = 0x18, 126 #define SEAD3_REG_CPLD_DATA_BUSY BIT(7) 127 }; 128 129 static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx) 130 { 131 unsigned int status; 132 int err; 133 134 do { 135 err = regmap_read(ctx->regmap, 136 ctx->offset + SEAD3_REG_CPLD_STATUS, 137 &status); 138 if (err) 139 return err; 140 } while (status & SEAD3_REG_CPLD_STATUS_BUSY); 141 142 return 0; 143 144 } 145 146 static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx) 147 { 148 unsigned int cpld_data; 149 int err; 150 151 err = sead3_wait_sm_idle(ctx); 152 if (err) 153 return err; 154 155 do { 156 err = regmap_read(ctx->regmap, 157 ctx->offset + SEAD3_REG_LCD_CTRL, 158 &cpld_data); 159 if (err) 160 return err; 161 162 err = sead3_wait_sm_idle(ctx); 163 if (err) 164 return err; 165 166 err = regmap_read(ctx->regmap, 167 ctx->offset + SEAD3_REG_CPLD_DATA, 168 &cpld_data); 169 if (err) 170 return err; 171 } while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY); 172 173 return 0; 174 } 175 176 static void sead3_update(struct img_ascii_lcd_ctx *ctx) 177 { 178 unsigned int i; 179 int err = 0; 180 181 for (i = 0; i < ctx->cfg->num_chars; i++) { 182 err = sead3_wait_lcd_idle(ctx); 183 if (err) 184 break; 185 186 err = regmap_write(ctx->regmap, 187 ctx->offset + SEAD3_REG_LCD_CTRL, 188 SEAD3_REG_LCD_CTRL_SETDRAM | i); 189 if (err) 190 break; 191 192 err = sead3_wait_lcd_idle(ctx); 193 if (err) 194 break; 195 196 err = regmap_write(ctx->regmap, 197 ctx->offset + SEAD3_REG_LCD_DATA, 198 ctx->curr[i]); 199 if (err) 200 break; 201 } 202 203 if (unlikely(err)) 204 pr_err_ratelimited("Failed to update LCD display: %d\n", err); 205 } 206 207 static struct img_ascii_lcd_config sead3_config = { 208 .num_chars = 16, 209 .external_regmap = true, 210 .update = sead3_update, 211 }; 212 213 static const struct of_device_id img_ascii_lcd_matches[] = { 214 { .compatible = "img,boston-lcd", .data = &boston_config }, 215 { .compatible = "mti,malta-lcd", .data = &malta_config }, 216 { .compatible = "mti,sead3-lcd", .data = &sead3_config }, 217 { /* sentinel */ } 218 }; 219 MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches); 220 221 /** 222 * img_ascii_lcd_scroll() - scroll the display by a character 223 * @t: really a pointer to the private data structure 224 * 225 * Scroll the current message along the LCD by one character, rearming the 226 * timer if required. 227 */ 228 static void img_ascii_lcd_scroll(struct timer_list *t) 229 { 230 struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer); 231 unsigned int i, ch = ctx->scroll_pos; 232 unsigned int num_chars = ctx->cfg->num_chars; 233 234 /* update the current message string */ 235 for (i = 0; i < num_chars;) { 236 /* copy as many characters from the string as possible */ 237 for (; i < num_chars && ch < ctx->message_len; i++, ch++) 238 ctx->curr[i] = ctx->message[ch]; 239 240 /* wrap around to the start of the string */ 241 ch = 0; 242 } 243 244 /* update the LCD */ 245 ctx->cfg->update(ctx); 246 247 /* move on to the next character */ 248 ctx->scroll_pos++; 249 ctx->scroll_pos %= ctx->message_len; 250 251 /* rearm the timer */ 252 if (ctx->message_len > ctx->cfg->num_chars) 253 mod_timer(&ctx->timer, jiffies + ctx->scroll_rate); 254 } 255 256 /** 257 * img_ascii_lcd_display() - set the message to be displayed 258 * @ctx: pointer to the private data structure 259 * @msg: the message to display 260 * @count: length of msg, or -1 261 * 262 * Display a new message @msg on the LCD. @msg can be longer than the number of 263 * characters the LCD can display, in which case it will begin scrolling across 264 * the LCD display. 265 * 266 * Return: 0 on success, -ENOMEM on memory allocation failure 267 */ 268 static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx, 269 const char *msg, ssize_t count) 270 { 271 char *new_msg; 272 273 /* stop the scroll timer */ 274 del_timer_sync(&ctx->timer); 275 276 if (count == -1) 277 count = strlen(msg); 278 279 /* if the string ends with a newline, trim it */ 280 if (msg[count - 1] == '\n') 281 count--; 282 283 new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL); 284 if (!new_msg) 285 return -ENOMEM; 286 287 memcpy(new_msg, msg, count); 288 new_msg[count] = 0; 289 290 if (ctx->message) 291 devm_kfree(&ctx->pdev->dev, ctx->message); 292 293 ctx->message = new_msg; 294 ctx->message_len = count; 295 ctx->scroll_pos = 0; 296 297 /* update the LCD */ 298 img_ascii_lcd_scroll(&ctx->timer); 299 300 return 0; 301 } 302 303 /** 304 * message_show() - read message via sysfs 305 * @dev: the LCD device 306 * @attr: the LCD message attribute 307 * @buf: the buffer to read the message into 308 * 309 * Read the current message being displayed or scrolled across the LCD display 310 * into @buf, for reads from sysfs. 311 * 312 * Return: the number of characters written to @buf 313 */ 314 static ssize_t message_show(struct device *dev, struct device_attribute *attr, 315 char *buf) 316 { 317 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 318 319 return sprintf(buf, "%s\n", ctx->message); 320 } 321 322 /** 323 * message_store() - write a new message via sysfs 324 * @dev: the LCD device 325 * @attr: the LCD message attribute 326 * @buf: the buffer containing the new message 327 * @count: the size of the message in @buf 328 * 329 * Write a new message to display or scroll across the LCD display from sysfs. 330 * 331 * Return: the size of the message on success, else -ERRNO 332 */ 333 static ssize_t message_store(struct device *dev, struct device_attribute *attr, 334 const char *buf, size_t count) 335 { 336 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 337 int err; 338 339 err = img_ascii_lcd_display(ctx, buf, count); 340 return err ?: count; 341 } 342 343 static DEVICE_ATTR_RW(message); 344 345 /** 346 * img_ascii_lcd_probe() - probe an LCD display device 347 * @pdev: the LCD platform device 348 * 349 * Probe an LCD display device, ensuring that we have the required resources in 350 * order to access the LCD & setting up private data as well as sysfs files. 351 * 352 * Return: 0 on success, else -ERRNO 353 */ 354 static int img_ascii_lcd_probe(struct platform_device *pdev) 355 { 356 const struct of_device_id *match; 357 const struct img_ascii_lcd_config *cfg; 358 struct img_ascii_lcd_ctx *ctx; 359 struct resource *res; 360 int err; 361 362 match = of_match_device(img_ascii_lcd_matches, &pdev->dev); 363 if (!match) 364 return -ENODEV; 365 366 cfg = match->data; 367 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars, 368 GFP_KERNEL); 369 if (!ctx) 370 return -ENOMEM; 371 372 if (cfg->external_regmap) { 373 ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); 374 if (IS_ERR(ctx->regmap)) 375 return PTR_ERR(ctx->regmap); 376 377 if (of_property_read_u32(pdev->dev.of_node, "offset", 378 &ctx->offset)) 379 return -EINVAL; 380 } else { 381 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 382 ctx->base = devm_ioremap_resource(&pdev->dev, res); 383 if (IS_ERR(ctx->base)) 384 return PTR_ERR(ctx->base); 385 } 386 387 ctx->pdev = pdev; 388 ctx->cfg = cfg; 389 ctx->message = NULL; 390 ctx->scroll_pos = 0; 391 ctx->scroll_rate = HZ / 2; 392 393 /* initialise a timer for scrolling the message */ 394 timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0); 395 396 platform_set_drvdata(pdev, ctx); 397 398 /* display a default message */ 399 err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1); 400 if (err) 401 goto out_del_timer; 402 403 err = device_create_file(&pdev->dev, &dev_attr_message); 404 if (err) 405 goto out_del_timer; 406 407 return 0; 408 out_del_timer: 409 del_timer_sync(&ctx->timer); 410 return err; 411 } 412 413 /** 414 * img_ascii_lcd_remove() - remove an LCD display device 415 * @pdev: the LCD platform device 416 * 417 * Remove an LCD display device, freeing private resources & ensuring that the 418 * driver stops using the LCD display registers. 419 * 420 * Return: 0 421 */ 422 static int img_ascii_lcd_remove(struct platform_device *pdev) 423 { 424 struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev); 425 426 device_remove_file(&pdev->dev, &dev_attr_message); 427 del_timer_sync(&ctx->timer); 428 return 0; 429 } 430 431 static struct platform_driver img_ascii_lcd_driver = { 432 .driver = { 433 .name = "img-ascii-lcd", 434 .of_match_table = img_ascii_lcd_matches, 435 }, 436 .probe = img_ascii_lcd_probe, 437 .remove = img_ascii_lcd_remove, 438 }; 439 module_platform_driver(img_ascii_lcd_driver); 440 441 MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display"); 442 MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>"); 443 MODULE_LICENSE("GPL"); 444