drivers/auxdisplay/img-ascii-lcd.c

   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         int err;
 360
 361         match = of_match_device(img_ascii_lcd_matches, &pdev->dev);
 362         if (!match)
 363                 return -ENODEV;
 364
 365         cfg = match->data;
 366         ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars,
 367                            GFP_KERNEL);
 368         if (!ctx)
 369                 return -ENOMEM;
 370
 371         if (cfg->external_regmap) {
 372                 ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node);
 373                 if (IS_ERR(ctx->regmap))
 374                         return PTR_ERR(ctx->regmap);
 375
 376                 if (of_property_read_u32(pdev->dev.of_node, "offset",
 377                                          &ctx->offset))
 378                         return -EINVAL;
 379         } else {
 380                 ctx->base = devm_platform_ioremap_resource(pdev, 0);
 381                 if (IS_ERR(ctx->base))
 382                         return PTR_ERR(ctx->base);
 383         }
 384
 385         ctx->pdev = pdev;
 386         ctx->cfg = cfg;
 387         ctx->message = NULL;
 388         ctx->scroll_pos = 0;
 389         ctx->scroll_rate = HZ / 2;
 390
 391         /* initialise a timer for scrolling the message */
 392         timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
 393
 394         platform_set_drvdata(pdev, ctx);
 395
 396         /* display a default message */
 397         err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE "       ", -1);
 398         if (err)
 399                 goto out_del_timer;
 400
 401         err = device_create_file(&pdev->dev, &dev_attr_message);
 402         if (err)
 403                 goto out_del_timer;
 404
 405         return 0;
 406 out_del_timer:
 407         del_timer_sync(&ctx->timer);
 408         return err;
 409 }
 410
 411 /**
 412  * img_ascii_lcd_remove() - remove an LCD display device
 413  * @pdev: the LCD platform device
 414  *
 415  * Remove an LCD display device, freeing private resources & ensuring that the
 416  * driver stops using the LCD display registers.
 417  *
 418  * Return: 0
 419  */
 420 static int img_ascii_lcd_remove(struct platform_device *pdev)
 421 {
 422         struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
 423
 424         device_remove_file(&pdev->dev, &dev_attr_message);
 425         del_timer_sync(&ctx->timer);
 426         return 0;
 427 }
 428
 429 static struct platform_driver img_ascii_lcd_driver = {
 430         .driver = {
 431                 .name           = "img-ascii-lcd",
 432                 .of_match_table = img_ascii_lcd_matches,
 433         },
 434         .probe  = img_ascii_lcd_probe,
 435         .remove = img_ascii_lcd_remove,
 436 };
 437 module_platform_driver(img_ascii_lcd_driver);
 438
 439 MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display");
 440 MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
 441 MODULE_LICENSE("GPL");