drivers/serial/serial.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * (C) Copyright 2004
   4  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   5  */
   6
   7 #include <common.h>
   8 #include <environment.h>
   9 #include <serial.h>
  10 #include <stdio_dev.h>
  11 #include <post.h>
  12 #include <linux/compiler.h>
  13 #include <errno.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 static struct serial_device *serial_devices;
  18 static struct serial_device *serial_current;
  19 /*
  20  * Table with supported baudrates (defined in config_xyz.h)
  21  */
  22 static const unsigned long baudrate_table[] = CONFIG_SYS_BAUDRATE_TABLE;
  23
  24 /**
  25  * serial_null() - Void registration routine of a serial driver
  26  *
  27  * This routine implements a void registration routine of a serial
  28  * driver. The registration routine of a particular driver is aliased
  29  * to this empty function in case the driver is not compiled into
  30  * U-Boot.
  31  */
  32 static void serial_null(void)
  33 {
  34 }
  35
  36 /**
  37  * on_baudrate() - Update the actual baudrate when the env var changes
  38  *
  39  * @name:       changed environment variable
  40  * @value:      new value of the environment variable
  41  * @op:         operation (create, overwrite, or delete)
  42  * @flags:      attributes of environment variable change,
  43  *              see flags H_* in include/search.h
  44  *
  45  * This will check for a valid baudrate and only apply it if valid.
  46  *
  47  * Return:      0 on success, 1 on error
  48  */
  49 static int on_baudrate(const char *name, const char *value, enum env_op op,
  50         int flags)
  51 {
  52         int i;
  53         int baudrate;
  54
  55         switch (op) {
  56         case env_op_create:
  57         case env_op_overwrite:
  58                 /*
  59                  * Switch to new baudrate if new baudrate is supported
  60                  */
  61                 baudrate = simple_strtoul(value, NULL, 10);
  62
  63                 /* Not actually changing */
  64                 if (gd->baudrate == baudrate)
  65                         return 0;
  66
  67                 for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) {
  68                         if (baudrate == baudrate_table[i])
  69                                 break;
  70                 }
  71                 if (i == ARRAY_SIZE(baudrate_table)) {
  72                         if ((flags & H_FORCE) == 0)
  73                                 printf("## Baudrate %d bps not supported\n",
  74                                         baudrate);
  75                         return 1;
  76                 }
  77                 if ((flags & H_INTERACTIVE) != 0) {
  78                         printf("## Switch baudrate to %d"
  79                                 " bps and press ENTER ...\n", baudrate);
  80                         udelay(50000);
  81                 }
  82
  83                 gd->baudrate = baudrate;
  84
  85                 serial_setbrg();
  86
  87                 udelay(50000);
  88
  89                 if ((flags & H_INTERACTIVE) != 0)
  90                         while (1) {
  91                                 if (getc() == '\r')
  92                                         break;
  93                         }
  94
  95                 return 0;
  96         case env_op_delete:
  97                 printf("## Baudrate may not be deleted\n");
  98                 return 1;
  99         default:
 100                 return 0;
 101         }
 102 }
 103 U_BOOT_ENV_CALLBACK(baudrate, on_baudrate);
 104
 105 /**
 106  * serial_initfunc() - Forward declare of driver registration routine
 107  * @name:       Name of the real driver registration routine.
 108  *
 109  * This macro expands onto forward declaration of a driver registration
 110  * routine, which is then used below in serial_initialize() function.
 111  * The declaration is made weak and aliases to serial_null() so in case
 112  * the driver is not compiled in, the function is still declared and can
 113  * be used, but aliases to serial_null() and thus is optimized away.
 114  */
 115 #define serial_initfunc(name)                                   \
 116         void name(void)                                         \
 117                 __attribute__((weak, alias("serial_null")));
 118
 119 serial_initfunc(atmel_serial_initialize);
 120 serial_initfunc(mcf_serial_initialize);
 121 serial_initfunc(mpc85xx_serial_initialize);
 122 serial_initfunc(mxc_serial_initialize);
 123 serial_initfunc(ns16550_serial_initialize);
 124 serial_initfunc(pl01x_serial_initialize);
 125 serial_initfunc(pxa_serial_initialize);
 126 serial_initfunc(sh_serial_initialize);
 127
 128 /**
 129  * serial_register() - Register serial driver with serial driver core
 130  * @dev:        Pointer to the serial driver structure
 131  *
 132  * This function registers the serial driver supplied via @dev with
 133  * serial driver core, thus making U-Boot aware of it and making it
 134  * available for U-Boot to use. On platforms that still require manual
 135  * relocation of constant variables, relocation of the supplied structure
 136  * is performed.
 137  */
 138 void serial_register(struct serial_device *dev)
 139 {
 140 #ifdef CONFIG_NEEDS_MANUAL_RELOC
 141         if (dev->start)
 142                 dev->start += gd->reloc_off;
 143         if (dev->stop)
 144                 dev->stop += gd->reloc_off;
 145         if (dev->setbrg)
 146                 dev->setbrg += gd->reloc_off;
 147         if (dev->getc)
 148                 dev->getc += gd->reloc_off;
 149         if (dev->tstc)
 150                 dev->tstc += gd->reloc_off;
 151         if (dev->putc)
 152                 dev->putc += gd->reloc_off;
 153         if (dev->puts)
 154                 dev->puts += gd->reloc_off;
 155 #endif
 156
 157         dev->next = serial_devices;
 158         serial_devices = dev;
 159 }
 160
 161 /**
 162  * serial_initialize() - Register all compiled-in serial port drivers
 163  *
 164  * This function registers all serial port drivers that are compiled
 165  * into the U-Boot binary with the serial core, thus making them
 166  * available to U-Boot to use. Lastly, this function assigns a default
 167  * serial port to the serial core. That serial port is then used as a
 168  * default output.
 169  */
 170 void serial_initialize(void)
 171 {
 172         atmel_serial_initialize();
 173         mcf_serial_initialize();
 174         mpc85xx_serial_initialize();
 175         mxc_serial_initialize();
 176         ns16550_serial_initialize();
 177         pl01x_serial_initialize();
 178         pxa_serial_initialize();
 179         sh_serial_initialize();
 180
 181         serial_assign(default_serial_console()->name);
 182 }
 183
 184 static int serial_stub_start(struct stdio_dev *sdev)
 185 {
 186         struct serial_device *dev = sdev->priv;
 187
 188         return dev->start();
 189 }
 190
 191 static int serial_stub_stop(struct stdio_dev *sdev)
 192 {
 193         struct serial_device *dev = sdev->priv;
 194
 195         return dev->stop();
 196 }
 197
 198 static void serial_stub_putc(struct stdio_dev *sdev, const char ch)
 199 {
 200         struct serial_device *dev = sdev->priv;
 201
 202         dev->putc(ch);
 203 }
 204
 205 static void serial_stub_puts(struct stdio_dev *sdev, const char *str)
 206 {
 207         struct serial_device *dev = sdev->priv;
 208
 209         dev->puts(str);
 210 }
 211
 212 static int serial_stub_getc(struct stdio_dev *sdev)
 213 {
 214         struct serial_device *dev = sdev->priv;
 215
 216         return dev->getc();
 217 }
 218
 219 static int serial_stub_tstc(struct stdio_dev *sdev)
 220 {
 221         struct serial_device *dev = sdev->priv;
 222
 223         return dev->tstc();
 224 }
 225
 226 /**
 227  * serial_stdio_init() - Register serial ports with STDIO core
 228  *
 229  * This function generates a proxy driver for each serial port driver.
 230  * These proxy drivers then register with the STDIO core, making the
 231  * serial drivers available as STDIO devices.
 232  */
 233 void serial_stdio_init(void)
 234 {
 235         struct stdio_dev dev;
 236         struct serial_device *s = serial_devices;
 237
 238         while (s) {
 239                 memset(&dev, 0, sizeof(dev));
 240
 241                 strcpy(dev.name, s->name);
 242                 dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT;
 243
 244                 dev.start = serial_stub_start;
 245                 dev.stop = serial_stub_stop;
 246                 dev.putc = serial_stub_putc;
 247                 dev.puts = serial_stub_puts;
 248                 dev.getc = serial_stub_getc;
 249                 dev.tstc = serial_stub_tstc;
 250                 dev.priv = s;
 251
 252                 stdio_register(&dev);
 253
 254                 s = s->next;
 255         }
 256 }
 257
 258 /**
 259  * serial_assign() - Select the serial output device by name
 260  * @name:       Name of the serial driver to be used as default output
 261  *
 262  * This function configures the serial output multiplexing by
 263  * selecting which serial device will be used as default. In case
 264  * the STDIO "serial" device is selected as stdin/stdout/stderr,
 265  * the serial device previously configured by this function will be
 266  * used for the particular operation.
 267  *
 268  * Returns 0 on success, negative on error.
 269  */
 270 int serial_assign(const char *name)
 271 {
 272         struct serial_device *s;
 273
 274         for (s = serial_devices; s; s = s->next) {
 275                 if (strcmp(s->name, name))
 276                         continue;
 277                 serial_current = s;
 278                 return 0;
 279         }
 280
 281         return -EINVAL;
 282 }
 283
 284 /**
 285  * serial_reinit_all() - Reinitialize all compiled-in serial ports
 286  *
 287  * This function reinitializes all serial ports that are compiled
 288  * into U-Boot by calling their serial_start() functions.
 289  */
 290 void serial_reinit_all(void)
 291 {
 292         struct serial_device *s;
 293
 294         for (s = serial_devices; s; s = s->next)
 295                 s->start();
 296 }
 297
 298 /**
 299  * get_current() - Return pointer to currently selected serial port
 300  *
 301  * This function returns a pointer to currently selected serial port.
 302  * The currently selected serial port is altered by serial_assign()
 303  * function.
 304  *
 305  * In case this function is called before relocation or before any serial
 306  * port is configured, this function calls default_serial_console() to
 307  * determine the serial port. Otherwise, the configured serial port is
 308  * returned.
 309  *
 310  * Returns pointer to the currently selected serial port on success,
 311  * NULL on error.
 312  */
 313 static struct serial_device *get_current(void)
 314 {
 315         struct serial_device *dev;
 316
 317         if (!(gd->flags & GD_FLG_RELOC))
 318                 dev = default_serial_console();
 319         else if (!serial_current)
 320                 dev = default_serial_console();
 321         else
 322                 dev = serial_current;
 323
 324         /* We must have a console device */
 325         if (!dev) {
 326 #ifdef CONFIG_SPL_BUILD
 327                 puts("Cannot find console\n");
 328                 hang();
 329 #else
 330                 panic("Cannot find console\n");
 331 #endif
 332         }
 333
 334         return dev;
 335 }
 336
 337 /**
 338  * serial_init() - Initialize currently selected serial port
 339  *
 340  * This function initializes the currently selected serial port. This
 341  * usually involves setting up the registers of that particular port,
 342  * enabling clock and such. This function uses the get_current() call
 343  * to determine which port is selected.
 344  *
 345  * Returns 0 on success, negative on error.
 346  */
 347 int serial_init(void)
 348 {
 349         gd->flags |= GD_FLG_SERIAL_READY;
 350         return get_current()->start();
 351 }
 352
 353 /**
 354  * serial_setbrg() - Configure baud-rate of currently selected serial port
 355  *
 356  * This function configures the baud-rate of the currently selected
 357  * serial port. The baud-rate is retrieved from global data within
 358  * the serial port driver. This function uses the get_current() call
 359  * to determine which port is selected.
 360  *
 361  * Returns 0 on success, negative on error.
 362  */
 363 void serial_setbrg(void)
 364 {
 365         get_current()->setbrg();
 366 }
 367
 368 /**
 369  * serial_getc() - Read character from currently selected serial port
 370  *
 371  * This function retrieves a character from currently selected serial
 372  * port. In case there is no character waiting on the serial port,
 373  * this function will block and wait for the character to appear. This
 374  * function uses the get_current() call to determine which port is
 375  * selected.
 376  *
 377  * Returns the character on success, negative on error.
 378  */
 379 int serial_getc(void)
 380 {
 381         return get_current()->getc();
 382 }
 383
 384 /**
 385  * serial_tstc() - Test if data is available on currently selected serial port
 386  *
 387  * This function tests if one or more characters are available on
 388  * currently selected serial port. This function never blocks. This
 389  * function uses the get_current() call to determine which port is
 390  * selected.
 391  *
 392  * Returns positive if character is available, zero otherwise.
 393  */
 394 int serial_tstc(void)
 395 {
 396         return get_current()->tstc();
 397 }
 398
 399 /**
 400  * serial_putc() - Output character via currently selected serial port
 401  * @c:  Single character to be output from the serial port.
 402  *
 403  * This function outputs a character via currently selected serial
 404  * port. This character is passed to the serial port driver responsible
 405  * for controlling the hardware. The hardware may still be in process
 406  * of transmitting another character, therefore this function may block
 407  * for a short amount of time. This function uses the get_current()
 408  * call to determine which port is selected.
 409  */
 410 void serial_putc(const char c)
 411 {
 412         get_current()->putc(c);
 413 }
 414
 415 /**
 416  * serial_puts() - Output string via currently selected serial port
 417  * @s:  Zero-terminated string to be output from the serial port.
 418  *
 419  * This function outputs a zero-terminated string via currently
 420  * selected serial port. This function behaves as an accelerator
 421  * in case the hardware can queue multiple characters for transfer.
 422  * The whole string that is to be output is available to the function
 423  * implementing the hardware manipulation. Transmitting the whole
 424  * string may take some time, thus this function may block for some
 425  * amount of time. This function uses the get_current() call to
 426  * determine which port is selected.
 427  */
 428 void serial_puts(const char *s)
 429 {
 430         get_current()->puts(s);
 431 }
 432
 433 /**
 434  * default_serial_puts() - Output string by calling serial_putc() in loop
 435  * @s:  Zero-terminated string to be output from the serial port.
 436  *
 437  * This function outputs a zero-terminated string by calling serial_putc()
 438  * in a loop. Most drivers do not support queueing more than one byte for
 439  * transfer, thus this function precisely implements their serial_puts().
 440  *
 441  * To optimize the number of get_current() calls, this function only
 442  * calls get_current() once and then directly accesses the putc() call
 443  * of the &struct serial_device .
 444  */
 445 void default_serial_puts(const char *s)
 446 {
 447         struct serial_device *dev = get_current();
 448         while (*s)
 449                 dev->putc(*s++);
 450 }
 451
 452 #if CONFIG_POST & CONFIG_SYS_POST_UART
 453 static const int bauds[] = CONFIG_SYS_BAUDRATE_TABLE;
 454
 455 /**
 456  * uart_post_test() - Test the currently selected serial port using POST
 457  * @flags:      POST framework flags
 458  *
 459  * Do a loopback test of the currently selected serial port. This
 460  * function is only useful in the context of the POST testing framwork.
 461  * The serial port is first configured into loopback mode and then
 462  * characters are sent through it.
 463  *
 464  * Returns 0 on success, value otherwise.
 465  */
 466 /* Mark weak until post/cpu/.../uart.c migrate over */
 467 __weak
 468 int uart_post_test(int flags)
 469 {
 470         unsigned char c;
 471         int ret, saved_baud, b;
 472         struct serial_device *saved_dev, *s;
 473
 474         /* Save current serial state */
 475         ret = 0;
 476         saved_dev = serial_current;
 477         saved_baud = gd->baudrate;
 478
 479         for (s = serial_devices; s; s = s->next) {
 480                 /* If this driver doesn't support loop back, skip it */
 481                 if (!s->loop)
 482                         continue;
 483
 484                 /* Test the next device */
 485                 serial_current = s;
 486
 487                 ret = serial_init();
 488                 if (ret)
 489                         goto done;
 490
 491                 /* Consume anything that happens to be queued */
 492                 while (serial_tstc())
 493                         serial_getc();
 494
 495                 /* Enable loop back */
 496                 s->loop(1);
 497
 498                 /* Test every available baud rate */
 499                 for (b = 0; b < ARRAY_SIZE(bauds); ++b) {
 500                         gd->baudrate = bauds[b];
 501                         serial_setbrg();
 502
 503                         /*
 504                          * Stick to printable chars to avoid issues:
 505                          *  - terminal corruption
 506                          *  - serial program reacting to sequences and sending
 507                          *    back random extra data
 508                          *  - most serial drivers add in extra chars (like \r\n)
 509                          */
 510                         for (c = 0x20; c < 0x7f; ++c) {
 511                                 /* Send it out */
 512                                 serial_putc(c);
 513
 514                                 /* Make sure it's the same one */
 515                                 ret = (c != serial_getc());
 516                                 if (ret) {
 517                                         s->loop(0);
 518                                         goto done;
 519                                 }
 520
 521                                 /* Clean up the output in case it was sent */
 522                                 serial_putc('\b');
 523                                 ret = ('\b' != serial_getc());
 524                                 if (ret) {
 525                                         s->loop(0);
 526                                         goto done;
 527                                 }
 528                         }
 529                 }
 530
 531                 /* Disable loop back */
 532                 s->loop(0);
 533
 534                 /* XXX: There is no serial_stop() !? */
 535                 if (s->stop)
 536                         s->stop();
 537         }
 538
 539  done:
 540         /* Restore previous serial state */
 541         serial_current = saved_dev;
 542         gd->baudrate = saved_baud;
 543         serial_reinit_all();
 544         serial_setbrg();
 545
 546         return ret;
 547 }
 548 #endif