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 }; 222 223 /** 224 * img_ascii_lcd_scroll() - scroll the display by a character 225 * @arg: really a pointer to the private data structure 226 * 227 * Scroll the current message along the LCD by one character, rearming the 228 * timer if required. 229 */ 230 static void img_ascii_lcd_scroll(unsigned long arg) 231 { 232 struct img_ascii_lcd_ctx *ctx = (struct img_ascii_lcd_ctx *)arg; 233 unsigned int i, ch = ctx->scroll_pos; 234 unsigned int num_chars = ctx->cfg->num_chars; 235 236 /* update the current message string */ 237 for (i = 0; i < num_chars;) { 238 /* copy as many characters from the string as possible */ 239 for (; i < num_chars && ch < ctx->message_len; i++, ch++) 240 ctx->curr[i] = ctx->message[ch]; 241 242 /* wrap around to the start of the string */ 243 ch = 0; 244 } 245 246 /* update the LCD */ 247 ctx->cfg->update(ctx); 248 249 /* move on to the next character */ 250 ctx->scroll_pos++; 251 ctx->scroll_pos %= ctx->message_len; 252 253 /* rearm the timer */ 254 if (ctx->message_len > ctx->cfg->num_chars) 255 mod_timer(&ctx->timer, jiffies + ctx->scroll_rate); 256 } 257 258 /** 259 * img_ascii_lcd_display() - set the message to be displayed 260 * @ctx: pointer to the private data structure 261 * @msg: the message to display 262 * @count: length of msg, or -1 263 * 264 * Display a new message @msg on the LCD. @msg can be longer than the number of 265 * characters the LCD can display, in which case it will begin scrolling across 266 * the LCD display. 267 * 268 * Return: 0 on success, -ENOMEM on memory allocation failure 269 */ 270 static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx, 271 const char *msg, ssize_t count) 272 { 273 char *new_msg; 274 275 /* stop the scroll timer */ 276 del_timer_sync(&ctx->timer); 277 278 if (count == -1) 279 count = strlen(msg); 280 281 /* if the string ends with a newline, trim it */ 282 if (msg[count - 1] == '\n') 283 count--; 284 285 new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL); 286 if (!new_msg) 287 return -ENOMEM; 288 289 memcpy(new_msg, msg, count); 290 new_msg[count] = 0; 291 292 if (ctx->message) 293 devm_kfree(&ctx->pdev->dev, ctx->message); 294 295 ctx->message = new_msg; 296 ctx->message_len = count; 297 ctx->scroll_pos = 0; 298 299 /* update the LCD */ 300 img_ascii_lcd_scroll((unsigned long)ctx); 301 302 return 0; 303 } 304 305 /** 306 * message_show() - read message via sysfs 307 * @dev: the LCD device 308 * @attr: the LCD message attribute 309 * @buf: the buffer to read the message into 310 * 311 * Read the current message being displayed or scrolled across the LCD display 312 * into @buf, for reads from sysfs. 313 * 314 * Return: the number of characters written to @buf 315 */ 316 static ssize_t message_show(struct device *dev, struct device_attribute *attr, 317 char *buf) 318 { 319 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 320 321 return sprintf(buf, "%s\n", ctx->message); 322 } 323 324 /** 325 * message_store() - write a new message via sysfs 326 * @dev: the LCD device 327 * @attr: the LCD message attribute 328 * @buf: the buffer containing the new message 329 * @count: the size of the message in @buf 330 * 331 * Write a new message to display or scroll across the LCD display from sysfs. 332 * 333 * Return: the size of the message on success, else -ERRNO 334 */ 335 static ssize_t message_store(struct device *dev, struct device_attribute *attr, 336 const char *buf, size_t count) 337 { 338 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 339 int err; 340 341 err = img_ascii_lcd_display(ctx, buf, count); 342 return err ?: count; 343 } 344 345 static DEVICE_ATTR_RW(message); 346 347 /** 348 * img_ascii_lcd_probe() - probe an LCD display device 349 * @pdev: the LCD platform device 350 * 351 * Probe an LCD display device, ensuring that we have the required resources in 352 * order to access the LCD & setting up private data as well as sysfs files. 353 * 354 * Return: 0 on success, else -ERRNO 355 */ 356 static int img_ascii_lcd_probe(struct platform_device *pdev) 357 { 358 const struct of_device_id *match; 359 const struct img_ascii_lcd_config *cfg; 360 struct img_ascii_lcd_ctx *ctx; 361 struct resource *res; 362 int err; 363 364 match = of_match_device(img_ascii_lcd_matches, &pdev->dev); 365 if (!match) 366 return -ENODEV; 367 368 cfg = match->data; 369 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars, 370 GFP_KERNEL); 371 if (!ctx) 372 return -ENOMEM; 373 374 if (cfg->external_regmap) { 375 ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); 376 if (IS_ERR(ctx->regmap)) 377 return PTR_ERR(ctx->regmap); 378 379 if (of_property_read_u32(pdev->dev.of_node, "offset", 380 &ctx->offset)) 381 return -EINVAL; 382 } else { 383 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 384 ctx->base = devm_ioremap_resource(&pdev->dev, res); 385 if (IS_ERR(ctx->base)) 386 return PTR_ERR(ctx->base); 387 } 388 389 ctx->pdev = pdev; 390 ctx->cfg = cfg; 391 ctx->message = NULL; 392 ctx->scroll_pos = 0; 393 ctx->scroll_rate = HZ / 2; 394 395 /* initialise a timer for scrolling the message */ 396 init_timer(&ctx->timer); 397 ctx->timer.function = img_ascii_lcd_scroll; 398 ctx->timer.data = (unsigned long)ctx; 399 400 platform_set_drvdata(pdev, ctx); 401 402 /* display a default message */ 403 err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1); 404 if (err) 405 goto out_del_timer; 406 407 err = device_create_file(&pdev->dev, &dev_attr_message); 408 if (err) 409 goto out_del_timer; 410 411 return 0; 412 out_del_timer: 413 del_timer_sync(&ctx->timer); 414 return err; 415 } 416 417 /** 418 * img_ascii_lcd_remove() - remove an LCD display device 419 * @pdev: the LCD platform device 420 * 421 * Remove an LCD display device, freeing private resources & ensuring that the 422 * driver stops using the LCD display registers. 423 * 424 * Return: 0 425 */ 426 static int img_ascii_lcd_remove(struct platform_device *pdev) 427 { 428 struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev); 429 430 device_remove_file(&pdev->dev, &dev_attr_message); 431 del_timer_sync(&ctx->timer); 432 return 0; 433 } 434 435 static struct platform_driver img_ascii_lcd_driver = { 436 .driver = { 437 .name = "img-ascii-lcd", 438 .of_match_table = img_ascii_lcd_matches, 439 }, 440 .probe = img_ascii_lcd_probe, 441 .remove = img_ascii_lcd_remove, 442 }; 443 module_platform_driver(img_ascii_lcd_driver); 444