uboot/drivers/serial/serial.c
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   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 <env_internal.h>
   9#include <hang.h>
  10#include <serial.h>
  11#include <stdio_dev.h>
  12#include <post.h>
  13#include <asm/global_data.h>
  14#include <linux/compiler.h>
  15#include <errno.h>
  16#include <linux/delay.h>
  17
  18DECLARE_GLOBAL_DATA_PTR;
  19
  20static struct serial_device *serial_devices;
  21static struct serial_device *serial_current;
  22/*
  23 * Table with supported baudrates (defined in config_xyz.h)
  24 */
  25static const unsigned long baudrate_table[] = CONFIG_SYS_BAUDRATE_TABLE;
  26
  27/**
  28 * serial_null() - Void registration routine of a serial driver
  29 *
  30 * This routine implements a void registration routine of a serial
  31 * driver. The registration routine of a particular driver is aliased
  32 * to this empty function in case the driver is not compiled into
  33 * U-Boot.
  34 */
  35static void serial_null(void)
  36{
  37}
  38
  39/**
  40 * on_baudrate() - Update the actual baudrate when the env var changes
  41 *
  42 * @name:       changed environment variable
  43 * @value:      new value of the environment variable
  44 * @op:         operation (create, overwrite, or delete)
  45 * @flags:      attributes of environment variable change,
  46 *              see flags H_* in include/search.h
  47 *
  48 * This will check for a valid baudrate and only apply it if valid.
  49 *
  50 * Return:      0 on success, 1 on error
  51 */
  52static int on_baudrate(const char *name, const char *value, enum env_op op,
  53        int flags)
  54{
  55        int i;
  56        int baudrate;
  57
  58        switch (op) {
  59        case env_op_create:
  60        case env_op_overwrite:
  61                /*
  62                 * Switch to new baudrate if new baudrate is supported
  63                 */
  64                baudrate = dectoul(value, NULL);
  65
  66                /* Not actually changing */
  67                if (gd->baudrate == baudrate)
  68                        return 0;
  69
  70                for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) {
  71                        if (baudrate == baudrate_table[i])
  72                                break;
  73                }
  74                if (i == ARRAY_SIZE(baudrate_table)) {
  75                        if ((flags & H_FORCE) == 0)
  76                                printf("## Baudrate %d bps not supported\n",
  77                                        baudrate);
  78                        return 1;
  79                }
  80                if ((flags & H_INTERACTIVE) != 0) {
  81                        printf("## Switch baudrate to %d"
  82                                " bps and press ENTER ...\n", baudrate);
  83                        udelay(50000);
  84                }
  85
  86                gd->baudrate = baudrate;
  87
  88                serial_setbrg();
  89
  90                udelay(50000);
  91
  92                if ((flags & H_INTERACTIVE) != 0)
  93                        while (1) {
  94                                if (getchar() == '\r')
  95                                        break;
  96                        }
  97
  98                return 0;
  99        case env_op_delete:
 100                printf("## Baudrate may not be deleted\n");
 101                return 1;
 102        default:
 103                return 0;
 104        }
 105}
 106U_BOOT_ENV_CALLBACK(baudrate, on_baudrate);
 107
 108/**
 109 * serial_initfunc() - Forward declare of driver registration routine
 110 * @name:       Name of the real driver registration routine.
 111 *
 112 * This macro expands onto forward declaration of a driver registration
 113 * routine, which is then used below in serial_initialize() function.
 114 * The declaration is made weak and aliases to serial_null() so in case
 115 * the driver is not compiled in, the function is still declared and can
 116 * be used, but aliases to serial_null() and thus is optimized away.
 117 */
 118#define serial_initfunc(name)                                   \
 119        void name(void)                                         \
 120                __attribute__((weak, alias("serial_null")));
 121
 122serial_initfunc(atmel_serial_initialize);
 123serial_initfunc(mcf_serial_initialize);
 124serial_initfunc(mpc85xx_serial_initialize);
 125serial_initfunc(mxc_serial_initialize);
 126serial_initfunc(ns16550_serial_initialize);
 127serial_initfunc(pl01x_serial_initialize);
 128serial_initfunc(pxa_serial_initialize);
 129serial_initfunc(smh_serial_initialize);
 130serial_initfunc(sh_serial_initialize);
 131serial_initfunc(mtk_serial_initialize);
 132
 133/**
 134 * serial_register() - Register serial driver with serial driver core
 135 * @dev:        Pointer to the serial driver structure
 136 *
 137 * This function registers the serial driver supplied via @dev with
 138 * serial driver core, thus making U-Boot aware of it and making it
 139 * available for U-Boot to use. On platforms that still require manual
 140 * relocation of constant variables, relocation of the supplied structure
 141 * is performed.
 142 */
 143void serial_register(struct serial_device *dev)
 144{
 145#ifdef CONFIG_NEEDS_MANUAL_RELOC
 146        if (dev->start)
 147                dev->start += gd->reloc_off;
 148        if (dev->stop)
 149                dev->stop += gd->reloc_off;
 150        if (dev->setbrg)
 151                dev->setbrg += gd->reloc_off;
 152        if (dev->getc)
 153                dev->getc += gd->reloc_off;
 154        if (dev->tstc)
 155                dev->tstc += gd->reloc_off;
 156        if (dev->putc)
 157                dev->putc += gd->reloc_off;
 158        if (dev->puts)
 159                dev->puts += gd->reloc_off;
 160#endif
 161
 162        dev->next = serial_devices;
 163        serial_devices = dev;
 164}
 165
 166/**
 167 * serial_initialize() - Register all compiled-in serial port drivers
 168 *
 169 * This function registers all serial port drivers that are compiled
 170 * into the U-Boot binary with the serial core, thus making them
 171 * available to U-Boot to use. Lastly, this function assigns a default
 172 * serial port to the serial core. That serial port is then used as a
 173 * default output.
 174 */
 175int serial_initialize(void)
 176{
 177        atmel_serial_initialize();
 178        mcf_serial_initialize();
 179        mpc85xx_serial_initialize();
 180        mxc_serial_initialize();
 181        ns16550_serial_initialize();
 182        pl01x_serial_initialize();
 183        pxa_serial_initialize();
 184        smh_serial_initialize();
 185        sh_serial_initialize();
 186        mtk_serial_initialize();
 187
 188        serial_assign(default_serial_console()->name);
 189
 190        return 0;
 191}
 192
 193static int serial_stub_start(struct stdio_dev *sdev)
 194{
 195        struct serial_device *dev = sdev->priv;
 196
 197        return dev->start();
 198}
 199
 200static int serial_stub_stop(struct stdio_dev *sdev)
 201{
 202        struct serial_device *dev = sdev->priv;
 203
 204        return dev->stop();
 205}
 206
 207static void serial_stub_putc(struct stdio_dev *sdev, const char ch)
 208{
 209        struct serial_device *dev = sdev->priv;
 210
 211        dev->putc(ch);
 212}
 213
 214static void serial_stub_puts(struct stdio_dev *sdev, const char *str)
 215{
 216        struct serial_device *dev = sdev->priv;
 217
 218        dev->puts(str);
 219}
 220
 221static int serial_stub_getc(struct stdio_dev *sdev)
 222{
 223        struct serial_device *dev = sdev->priv;
 224
 225        return dev->getc();
 226}
 227
 228static int serial_stub_tstc(struct stdio_dev *sdev)
 229{
 230        struct serial_device *dev = sdev->priv;
 231
 232        return dev->tstc();
 233}
 234
 235/**
 236 * serial_stdio_init() - Register serial ports with STDIO core
 237 *
 238 * This function generates a proxy driver for each serial port driver.
 239 * These proxy drivers then register with the STDIO core, making the
 240 * serial drivers available as STDIO devices.
 241 */
 242void serial_stdio_init(void)
 243{
 244        struct stdio_dev dev;
 245        struct serial_device *s = serial_devices;
 246
 247        while (s) {
 248                memset(&dev, 0, sizeof(dev));
 249
 250                strcpy(dev.name, s->name);
 251                dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT;
 252
 253                dev.start = serial_stub_start;
 254                dev.stop = serial_stub_stop;
 255                dev.putc = serial_stub_putc;
 256                dev.puts = serial_stub_puts;
 257                dev.getc = serial_stub_getc;
 258                dev.tstc = serial_stub_tstc;
 259                dev.priv = s;
 260
 261                stdio_register(&dev);
 262
 263                s = s->next;
 264        }
 265}
 266
 267/**
 268 * serial_assign() - Select the serial output device by name
 269 * @name:       Name of the serial driver to be used as default output
 270 *
 271 * This function configures the serial output multiplexing by
 272 * selecting which serial device will be used as default. In case
 273 * the STDIO "serial" device is selected as stdin/stdout/stderr,
 274 * the serial device previously configured by this function will be
 275 * used for the particular operation.
 276 *
 277 * Returns 0 on success, negative on error.
 278 */
 279int serial_assign(const char *name)
 280{
 281        struct serial_device *s;
 282
 283        for (s = serial_devices; s; s = s->next) {
 284                if (strcmp(s->name, name))
 285                        continue;
 286                serial_current = s;
 287                return 0;
 288        }
 289
 290        return -EINVAL;
 291}
 292
 293/**
 294 * serial_reinit_all() - Reinitialize all compiled-in serial ports
 295 *
 296 * This function reinitializes all serial ports that are compiled
 297 * into U-Boot by calling their serial_start() functions.
 298 */
 299void serial_reinit_all(void)
 300{
 301        struct serial_device *s;
 302
 303        for (s = serial_devices; s; s = s->next)
 304                s->start();
 305}
 306
 307/**
 308 * get_current() - Return pointer to currently selected serial port
 309 *
 310 * This function returns a pointer to currently selected serial port.
 311 * The currently selected serial port is altered by serial_assign()
 312 * function.
 313 *
 314 * In case this function is called before relocation or before any serial
 315 * port is configured, this function calls default_serial_console() to
 316 * determine the serial port. Otherwise, the configured serial port is
 317 * returned.
 318 *
 319 * Returns pointer to the currently selected serial port on success,
 320 * NULL on error.
 321 */
 322static struct serial_device *get_current(void)
 323{
 324        struct serial_device *dev;
 325
 326        if (!(gd->flags & GD_FLG_RELOC))
 327                dev = default_serial_console();
 328        else if (!serial_current)
 329                dev = default_serial_console();
 330        else
 331                dev = serial_current;
 332
 333        /* We must have a console device */
 334        if (!dev) {
 335#ifdef CONFIG_SPL_BUILD
 336                puts("Cannot find console\n");
 337                hang();
 338#else
 339                panic("Cannot find console\n");
 340#endif
 341        }
 342
 343        return dev;
 344}
 345
 346/**
 347 * serial_init() - Initialize currently selected serial port
 348 *
 349 * This function initializes the currently selected serial port. This
 350 * usually involves setting up the registers of that particular port,
 351 * enabling clock and such. This function uses the get_current() call
 352 * to determine which port is selected.
 353 *
 354 * Returns 0 on success, negative on error.
 355 */
 356int serial_init(void)
 357{
 358        gd->flags |= GD_FLG_SERIAL_READY;
 359        return get_current()->start();
 360}
 361
 362/**
 363 * serial_setbrg() - Configure baud-rate of currently selected serial port
 364 *
 365 * This function configures the baud-rate of the currently selected
 366 * serial port. The baud-rate is retrieved from global data within
 367 * the serial port driver. This function uses the get_current() call
 368 * to determine which port is selected.
 369 *
 370 * Returns 0 on success, negative on error.
 371 */
 372void serial_setbrg(void)
 373{
 374        get_current()->setbrg();
 375}
 376
 377/**
 378 * serial_getc() - Read character from currently selected serial port
 379 *
 380 * This function retrieves a character from currently selected serial
 381 * port. In case there is no character waiting on the serial port,
 382 * this function will block and wait for the character to appear. This
 383 * function uses the get_current() call to determine which port is
 384 * selected.
 385 *
 386 * Returns the character on success, negative on error.
 387 */
 388int serial_getc(void)
 389{
 390        return get_current()->getc();
 391}
 392
 393/**
 394 * serial_tstc() - Test if data is available on currently selected serial port
 395 *
 396 * This function tests if one or more characters are available on
 397 * currently selected serial port. This function never blocks. This
 398 * function uses the get_current() call to determine which port is
 399 * selected.
 400 *
 401 * Returns positive if character is available, zero otherwise.
 402 */
 403int serial_tstc(void)
 404{
 405        return get_current()->tstc();
 406}
 407
 408/**
 409 * serial_putc() - Output character via currently selected serial port
 410 * @c:  Single character to be output from the serial port.
 411 *
 412 * This function outputs a character via currently selected serial
 413 * port. This character is passed to the serial port driver responsible
 414 * for controlling the hardware. The hardware may still be in process
 415 * of transmitting another character, therefore this function may block
 416 * for a short amount of time. This function uses the get_current()
 417 * call to determine which port is selected.
 418 */
 419void serial_putc(const char c)
 420{
 421        get_current()->putc(c);
 422}
 423
 424/**
 425 * serial_puts() - Output string via currently selected serial port
 426 * @s:  Zero-terminated string to be output from the serial port.
 427 *
 428 * This function outputs a zero-terminated string via currently
 429 * selected serial port. This function behaves as an accelerator
 430 * in case the hardware can queue multiple characters for transfer.
 431 * The whole string that is to be output is available to the function
 432 * implementing the hardware manipulation. Transmitting the whole
 433 * string may take some time, thus this function may block for some
 434 * amount of time. This function uses the get_current() call to
 435 * determine which port is selected.
 436 */
 437void serial_puts(const char *s)
 438{
 439        get_current()->puts(s);
 440}
 441
 442/**
 443 * default_serial_puts() - Output string by calling serial_putc() in loop
 444 * @s:  Zero-terminated string to be output from the serial port.
 445 *
 446 * This function outputs a zero-terminated string by calling serial_putc()
 447 * in a loop. Most drivers do not support queueing more than one byte for
 448 * transfer, thus this function precisely implements their serial_puts().
 449 *
 450 * To optimize the number of get_current() calls, this function only
 451 * calls get_current() once and then directly accesses the putc() call
 452 * of the &struct serial_device .
 453 */
 454void default_serial_puts(const char *s)
 455{
 456        struct serial_device *dev = get_current();
 457        while (*s)
 458                dev->putc(*s++);
 459}
 460
 461#if CONFIG_POST & CONFIG_SYS_POST_UART
 462static const int bauds[] = CONFIG_SYS_BAUDRATE_TABLE;
 463
 464/**
 465 * uart_post_test() - Test the currently selected serial port using POST
 466 * @flags:      POST framework flags
 467 *
 468 * Do a loopback test of the currently selected serial port. This
 469 * function is only useful in the context of the POST testing framwork.
 470 * The serial port is first configured into loopback mode and then
 471 * characters are sent through it.
 472 *
 473 * Returns 0 on success, value otherwise.
 474 */
 475/* Mark weak until post/cpu/.../uart.c migrate over */
 476__weak
 477int uart_post_test(int flags)
 478{
 479        unsigned char c;
 480        int ret, saved_baud, b;
 481        struct serial_device *saved_dev, *s;
 482
 483        /* Save current serial state */
 484        ret = 0;
 485        saved_dev = serial_current;
 486        saved_baud = gd->baudrate;
 487
 488        for (s = serial_devices; s; s = s->next) {
 489                /* If this driver doesn't support loop back, skip it */
 490                if (!s->loop)
 491                        continue;
 492
 493                /* Test the next device */
 494                serial_current = s;
 495
 496                ret = serial_init();
 497                if (ret)
 498                        goto done;
 499
 500                /* Consume anything that happens to be queued */
 501                while (serial_tstc())
 502                        serial_getc();
 503
 504                /* Enable loop back */
 505                s->loop(1);
 506
 507                /* Test every available baud rate */
 508                for (b = 0; b < ARRAY_SIZE(bauds); ++b) {
 509                        gd->baudrate = bauds[b];
 510                        serial_setbrg();
 511
 512                        /*
 513                         * Stick to printable chars to avoid issues:
 514                         *  - terminal corruption
 515                         *  - serial program reacting to sequences and sending
 516                         *    back random extra data
 517                         *  - most serial drivers add in extra chars (like \r\n)
 518                         */
 519                        for (c = 0x20; c < 0x7f; ++c) {
 520                                /* Send it out */
 521                                serial_putc(c);
 522
 523                                /* Make sure it's the same one */
 524                                ret = (c != serial_getc());
 525                                if (ret) {
 526                                        s->loop(0);
 527                                        goto done;
 528                                }
 529
 530                                /* Clean up the output in case it was sent */
 531                                serial_putc('\b');
 532                                ret = ('\b' != serial_getc());
 533                                if (ret) {
 534                                        s->loop(0);
 535                                        goto done;
 536                                }
 537                        }
 538                }
 539
 540                /* Disable loop back */
 541                s->loop(0);
 542
 543                /* XXX: There is no serial_stop() !? */
 544                if (s->stop)
 545                        s->stop();
 546        }
 547
 548 done:
 549        /* Restore previous serial state */
 550        serial_current = saved_dev;
 551        gd->baudrate = saved_baud;
 552        serial_reinit_all();
 553        serial_setbrg();
 554
 555        return ret;
 556}
 557#endif
 558