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 }; 223 224 /** 225 * img_ascii_lcd_scroll() - scroll the display by a character 226 * @arg: really a pointer to the private data structure 227 * 228 * Scroll the current message along the LCD by one character, rearming the 229 * timer if required. 230 */ 231 static void img_ascii_lcd_scroll(unsigned long arg) 232 { 233 struct img_ascii_lcd_ctx *ctx = (struct img_ascii_lcd_ctx *)arg; 234 unsigned int i, ch = ctx->scroll_pos; 235 unsigned int num_chars = ctx->cfg->num_chars; 236 237 /* update the current message string */ 238 for (i = 0; i < num_chars;) { 239 /* copy as many characters from the string as possible */ 240 for (; i < num_chars && ch < ctx->message_len; i++, ch++) 241 ctx->curr[i] = ctx->message[ch]; 242 243 /* wrap around to the start of the string */ 244 ch = 0; 245 } 246 247 /* update the LCD */ 248 ctx->cfg->update(ctx); 249 250 /* move on to the next character */ 251 ctx->scroll_pos++; 252 ctx->scroll_pos %= ctx->message_len; 253 254 /* rearm the timer */ 255 if (ctx->message_len > ctx->cfg->num_chars) 256 mod_timer(&ctx->timer, jiffies + ctx->scroll_rate); 257 } 258 259 /** 260 * img_ascii_lcd_display() - set the message to be displayed 261 * @ctx: pointer to the private data structure 262 * @msg: the message to display 263 * @count: length of msg, or -1 264 * 265 * Display a new message @msg on the LCD. @msg can be longer than the number of 266 * characters the LCD can display, in which case it will begin scrolling across 267 * the LCD display. 268 * 269 * Return: 0 on success, -ENOMEM on memory allocation failure 270 */ 271 static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx, 272 const char *msg, ssize_t count) 273 { 274 char *new_msg; 275 276 /* stop the scroll timer */ 277 del_timer_sync(&ctx->timer); 278 279 if (count == -1) 280 count = strlen(msg); 281 282 /* if the string ends with a newline, trim it */ 283 if (msg[count - 1] == '\n') 284 count--; 285 286 new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL); 287 if (!new_msg) 288 return -ENOMEM; 289 290 memcpy(new_msg, msg, count); 291 new_msg[count] = 0; 292 293 if (ctx->message) 294 devm_kfree(&ctx->pdev->dev, ctx->message); 295 296 ctx->message = new_msg; 297 ctx->message_len = count; 298 ctx->scroll_pos = 0; 299 300 /* update the LCD */ 301 img_ascii_lcd_scroll((unsigned long)ctx); 302 303 return 0; 304 } 305 306 /** 307 * message_show() - read message via sysfs 308 * @dev: the LCD device 309 * @attr: the LCD message attribute 310 * @buf: the buffer to read the message into 311 * 312 * Read the current message being displayed or scrolled across the LCD display 313 * into @buf, for reads from sysfs. 314 * 315 * Return: the number of characters written to @buf 316 */ 317 static ssize_t message_show(struct device *dev, struct device_attribute *attr, 318 char *buf) 319 { 320 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 321 322 return sprintf(buf, "%s\n", ctx->message); 323 } 324 325 /** 326 * message_store() - write a new message via sysfs 327 * @dev: the LCD device 328 * @attr: the LCD message attribute 329 * @buf: the buffer containing the new message 330 * @count: the size of the message in @buf 331 * 332 * Write a new message to display or scroll across the LCD display from sysfs. 333 * 334 * Return: the size of the message on success, else -ERRNO 335 */ 336 static ssize_t message_store(struct device *dev, struct device_attribute *attr, 337 const char *buf, size_t count) 338 { 339 struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev); 340 int err; 341 342 err = img_ascii_lcd_display(ctx, buf, count); 343 return err ?: count; 344 } 345 346 static DEVICE_ATTR_RW(message); 347 348 /** 349 * img_ascii_lcd_probe() - probe an LCD display device 350 * @pdev: the LCD platform device 351 * 352 * Probe an LCD display device, ensuring that we have the required resources in 353 * order to access the LCD & setting up private data as well as sysfs files. 354 * 355 * Return: 0 on success, else -ERRNO 356 */ 357 static int img_ascii_lcd_probe(struct platform_device *pdev) 358 { 359 const struct of_device_id *match; 360 const struct img_ascii_lcd_config *cfg; 361 struct img_ascii_lcd_ctx *ctx; 362 struct resource *res; 363 int err; 364 365 match = of_match_device(img_ascii_lcd_matches, &pdev->dev); 366 if (!match) 367 return -ENODEV; 368 369 cfg = match->data; 370 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars, 371 GFP_KERNEL); 372 if (!ctx) 373 return -ENOMEM; 374 375 if (cfg->external_regmap) { 376 ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node); 377 if (IS_ERR(ctx->regmap)) 378 return PTR_ERR(ctx->regmap); 379 380 if (of_property_read_u32(pdev->dev.of_node, "offset", 381 &ctx->offset)) 382 return -EINVAL; 383 } else { 384 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 385 ctx->base = devm_ioremap_resource(&pdev->dev, res); 386 if (IS_ERR(ctx->base)) 387 return PTR_ERR(ctx->base); 388 } 389 390 ctx->pdev = pdev; 391 ctx->cfg = cfg; 392 ctx->message = NULL; 393 ctx->scroll_pos = 0; 394 ctx->scroll_rate = HZ / 2; 395 396 /* initialise a timer for scrolling the message */ 397 init_timer(&ctx->timer); 398 ctx->timer.function = img_ascii_lcd_scroll; 399 ctx->timer.data = (unsigned long)ctx; 400 401 platform_set_drvdata(pdev, ctx); 402 403 /* display a default message */ 404 err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1); 405 if (err) 406 goto out_del_timer; 407 408 err = device_create_file(&pdev->dev, &dev_attr_message); 409 if (err) 410 goto out_del_timer; 411 412 return 0; 413 out_del_timer: 414 del_timer_sync(&ctx->timer); 415 return err; 416 } 417 418 /** 419 * img_ascii_lcd_remove() - remove an LCD display device 420 * @pdev: the LCD platform device 421 * 422 * Remove an LCD display device, freeing private resources & ensuring that the 423 * driver stops using the LCD display registers. 424 * 425 * Return: 0 426 */ 427 static int img_ascii_lcd_remove(struct platform_device *pdev) 428 { 429 struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev); 430 431 device_remove_file(&pdev->dev, &dev_attr_message); 432 del_timer_sync(&ctx->timer); 433 return 0; 434 } 435 436 static struct platform_driver img_ascii_lcd_driver = { 437 .driver = { 438 .name = "img-ascii-lcd", 439 .of_match_table = img_ascii_lcd_matches, 440 }, 441 .probe = img_ascii_lcd_probe, 442 .remove = img_ascii_lcd_remove, 443 }; 444 module_platform_driver(img_ascii_lcd_driver); 445