linux/drivers/tty/serial/apbuart.c
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   1/*
   2 *  Driver for GRLIB serial ports (APBUART)
   3 *
   4 *  Based on linux/drivers/serial/amba.c
   5 *
   6 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
   7 *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
   8 *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
   9 *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
  10 *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
  11 */
  12
  13#if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
  14#define SUPPORT_SYSRQ
  15#endif
  16
  17#include <linux/module.h>
  18#include <linux/tty.h>
  19#include <linux/tty_flip.h>
  20#include <linux/ioport.h>
  21#include <linux/init.h>
  22#include <linux/serial.h>
  23#include <linux/console.h>
  24#include <linux/sysrq.h>
  25#include <linux/kthread.h>
  26#include <linux/device.h>
  27#include <linux/of.h>
  28#include <linux/of_device.h>
  29#include <linux/of_platform.h>
  30#include <linux/of_irq.h>
  31#include <linux/platform_device.h>
  32#include <linux/io.h>
  33#include <linux/serial_core.h>
  34#include <asm/irq.h>
  35
  36#include "apbuart.h"
  37
  38#define SERIAL_APBUART_MAJOR    TTY_MAJOR
  39#define SERIAL_APBUART_MINOR    64
  40#define UART_DUMMY_RSR_RX       0x8000  /* for ignore all read */
  41
  42static void apbuart_tx_chars(struct uart_port *port);
  43
  44static void apbuart_stop_tx(struct uart_port *port)
  45{
  46        unsigned int cr;
  47
  48        cr = UART_GET_CTRL(port);
  49        cr &= ~UART_CTRL_TI;
  50        UART_PUT_CTRL(port, cr);
  51}
  52
  53static void apbuart_start_tx(struct uart_port *port)
  54{
  55        unsigned int cr;
  56
  57        cr = UART_GET_CTRL(port);
  58        cr |= UART_CTRL_TI;
  59        UART_PUT_CTRL(port, cr);
  60
  61        if (UART_GET_STATUS(port) & UART_STATUS_THE)
  62                apbuart_tx_chars(port);
  63}
  64
  65static void apbuart_stop_rx(struct uart_port *port)
  66{
  67        unsigned int cr;
  68
  69        cr = UART_GET_CTRL(port);
  70        cr &= ~(UART_CTRL_RI);
  71        UART_PUT_CTRL(port, cr);
  72}
  73
  74static void apbuart_rx_chars(struct uart_port *port)
  75{
  76        unsigned int status, ch, rsr, flag;
  77        unsigned int max_chars = port->fifosize;
  78
  79        status = UART_GET_STATUS(port);
  80
  81        while (UART_RX_DATA(status) && (max_chars--)) {
  82
  83                ch = UART_GET_CHAR(port);
  84                flag = TTY_NORMAL;
  85
  86                port->icount.rx++;
  87
  88                rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
  89                UART_PUT_STATUS(port, 0);
  90                if (rsr & UART_STATUS_ERR) {
  91
  92                        if (rsr & UART_STATUS_BR) {
  93                                rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
  94                                port->icount.brk++;
  95                                if (uart_handle_break(port))
  96                                        goto ignore_char;
  97                        } else if (rsr & UART_STATUS_PE) {
  98                                port->icount.parity++;
  99                        } else if (rsr & UART_STATUS_FE) {
 100                                port->icount.frame++;
 101                        }
 102                        if (rsr & UART_STATUS_OE)
 103                                port->icount.overrun++;
 104
 105                        rsr &= port->read_status_mask;
 106
 107                        if (rsr & UART_STATUS_PE)
 108                                flag = TTY_PARITY;
 109                        else if (rsr & UART_STATUS_FE)
 110                                flag = TTY_FRAME;
 111                }
 112
 113                if (uart_handle_sysrq_char(port, ch))
 114                        goto ignore_char;
 115
 116                uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
 117
 118
 119              ignore_char:
 120                status = UART_GET_STATUS(port);
 121        }
 122
 123        spin_unlock(&port->lock);
 124        tty_flip_buffer_push(&port->state->port);
 125        spin_lock(&port->lock);
 126}
 127
 128static void apbuart_tx_chars(struct uart_port *port)
 129{
 130        struct circ_buf *xmit = &port->state->xmit;
 131        int count;
 132
 133        if (port->x_char) {
 134                UART_PUT_CHAR(port, port->x_char);
 135                port->icount.tx++;
 136                port->x_char = 0;
 137                return;
 138        }
 139
 140        if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 141                apbuart_stop_tx(port);
 142                return;
 143        }
 144
 145        /* amba: fill FIFO */
 146        count = port->fifosize >> 1;
 147        do {
 148                UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 149                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 150                port->icount.tx++;
 151                if (uart_circ_empty(xmit))
 152                        break;
 153        } while (--count > 0);
 154
 155        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 156                uart_write_wakeup(port);
 157
 158        if (uart_circ_empty(xmit))
 159                apbuart_stop_tx(port);
 160}
 161
 162static irqreturn_t apbuart_int(int irq, void *dev_id)
 163{
 164        struct uart_port *port = dev_id;
 165        unsigned int status;
 166
 167        spin_lock(&port->lock);
 168
 169        status = UART_GET_STATUS(port);
 170        if (status & UART_STATUS_DR)
 171                apbuart_rx_chars(port);
 172        if (status & UART_STATUS_THE)
 173                apbuart_tx_chars(port);
 174
 175        spin_unlock(&port->lock);
 176
 177        return IRQ_HANDLED;
 178}
 179
 180static unsigned int apbuart_tx_empty(struct uart_port *port)
 181{
 182        unsigned int status = UART_GET_STATUS(port);
 183        return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
 184}
 185
 186static unsigned int apbuart_get_mctrl(struct uart_port *port)
 187{
 188        /* The GRLIB APBUART handles flow control in hardware */
 189        return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 190}
 191
 192static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 193{
 194        /* The GRLIB APBUART handles flow control in hardware */
 195}
 196
 197static void apbuart_break_ctl(struct uart_port *port, int break_state)
 198{
 199        /* We don't support sending break */
 200}
 201
 202static int apbuart_startup(struct uart_port *port)
 203{
 204        int retval;
 205        unsigned int cr;
 206
 207        /* Allocate the IRQ */
 208        retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
 209        if (retval)
 210                return retval;
 211
 212        /* Finally, enable interrupts */
 213        cr = UART_GET_CTRL(port);
 214        UART_PUT_CTRL(port,
 215                      cr | UART_CTRL_RE | UART_CTRL_TE |
 216                      UART_CTRL_RI | UART_CTRL_TI);
 217
 218        return 0;
 219}
 220
 221static void apbuart_shutdown(struct uart_port *port)
 222{
 223        unsigned int cr;
 224
 225        /* disable all interrupts, disable the port */
 226        cr = UART_GET_CTRL(port);
 227        UART_PUT_CTRL(port,
 228                      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
 229                             UART_CTRL_RI | UART_CTRL_TI));
 230
 231        /* Free the interrupt */
 232        free_irq(port->irq, port);
 233}
 234
 235static void apbuart_set_termios(struct uart_port *port,
 236                                struct ktermios *termios, struct ktermios *old)
 237{
 238        unsigned int cr;
 239        unsigned long flags;
 240        unsigned int baud, quot;
 241
 242        /* Ask the core to calculate the divisor for us. */
 243        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 244        if (baud == 0)
 245                panic("invalid baudrate %i\n", port->uartclk / 16);
 246
 247        /* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
 248        quot = (uart_get_divisor(port, baud)) * 2;
 249        cr = UART_GET_CTRL(port);
 250        cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
 251
 252        if (termios->c_cflag & PARENB) {
 253                cr |= UART_CTRL_PE;
 254                if ((termios->c_cflag & PARODD))
 255                        cr |= UART_CTRL_PS;
 256        }
 257
 258        /* Enable flow control. */
 259        if (termios->c_cflag & CRTSCTS)
 260                cr |= UART_CTRL_FL;
 261
 262        spin_lock_irqsave(&port->lock, flags);
 263
 264        /* Update the per-port timeout. */
 265        uart_update_timeout(port, termios->c_cflag, baud);
 266
 267        port->read_status_mask = UART_STATUS_OE;
 268        if (termios->c_iflag & INPCK)
 269                port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 270
 271        /* Characters to ignore */
 272        port->ignore_status_mask = 0;
 273        if (termios->c_iflag & IGNPAR)
 274                port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 275
 276        /* Ignore all characters if CREAD is not set. */
 277        if ((termios->c_cflag & CREAD) == 0)
 278                port->ignore_status_mask |= UART_DUMMY_RSR_RX;
 279
 280        /* Set baud rate */
 281        quot -= 1;
 282        UART_PUT_SCAL(port, quot);
 283        UART_PUT_CTRL(port, cr);
 284
 285        spin_unlock_irqrestore(&port->lock, flags);
 286}
 287
 288static const char *apbuart_type(struct uart_port *port)
 289{
 290        return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
 291}
 292
 293static void apbuart_release_port(struct uart_port *port)
 294{
 295        release_mem_region(port->mapbase, 0x100);
 296}
 297
 298static int apbuart_request_port(struct uart_port *port)
 299{
 300        return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
 301            != NULL ? 0 : -EBUSY;
 302        return 0;
 303}
 304
 305/* Configure/autoconfigure the port */
 306static void apbuart_config_port(struct uart_port *port, int flags)
 307{
 308        if (flags & UART_CONFIG_TYPE) {
 309                port->type = PORT_APBUART;
 310                apbuart_request_port(port);
 311        }
 312}
 313
 314/* Verify the new serial_struct (for TIOCSSERIAL) */
 315static int apbuart_verify_port(struct uart_port *port,
 316                               struct serial_struct *ser)
 317{
 318        int ret = 0;
 319        if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
 320                ret = -EINVAL;
 321        if (ser->irq < 0 || ser->irq >= NR_IRQS)
 322                ret = -EINVAL;
 323        if (ser->baud_base < 9600)
 324                ret = -EINVAL;
 325        return ret;
 326}
 327
 328static struct uart_ops grlib_apbuart_ops = {
 329        .tx_empty = apbuart_tx_empty,
 330        .set_mctrl = apbuart_set_mctrl,
 331        .get_mctrl = apbuart_get_mctrl,
 332        .stop_tx = apbuart_stop_tx,
 333        .start_tx = apbuart_start_tx,
 334        .stop_rx = apbuart_stop_rx,
 335        .break_ctl = apbuart_break_ctl,
 336        .startup = apbuart_startup,
 337        .shutdown = apbuart_shutdown,
 338        .set_termios = apbuart_set_termios,
 339        .type = apbuart_type,
 340        .release_port = apbuart_release_port,
 341        .request_port = apbuart_request_port,
 342        .config_port = apbuart_config_port,
 343        .verify_port = apbuart_verify_port,
 344};
 345
 346static struct uart_port grlib_apbuart_ports[UART_NR];
 347static struct device_node *grlib_apbuart_nodes[UART_NR];
 348
 349static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
 350{
 351        int ctrl, loop = 0;
 352        int status;
 353        int fifosize;
 354        unsigned long flags;
 355
 356        ctrl = UART_GET_CTRL(port);
 357
 358        /*
 359         * Enable the transceiver and wait for it to be ready to send data.
 360         * Clear interrupts so that this process will not be externally
 361         * interrupted in the middle (which can cause the transceiver to
 362         * drain prematurely).
 363         */
 364
 365        local_irq_save(flags);
 366
 367        UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
 368
 369        while (!UART_TX_READY(UART_GET_STATUS(port)))
 370                loop++;
 371
 372        /*
 373         * Disable the transceiver so data isn't actually sent during the
 374         * actual test.
 375         */
 376
 377        UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
 378
 379        fifosize = 1;
 380        UART_PUT_CHAR(port, 0);
 381
 382        /*
 383         * So long as transmitting a character increments the tranceivier FIFO
 384         * length the FIFO must be at least that big. These bytes will
 385         * automatically drain off of the FIFO.
 386         */
 387
 388        status = UART_GET_STATUS(port);
 389        while (((status >> 20) & 0x3F) == fifosize) {
 390                fifosize++;
 391                UART_PUT_CHAR(port, 0);
 392                status = UART_GET_STATUS(port);
 393        }
 394
 395        fifosize--;
 396
 397        UART_PUT_CTRL(port, ctrl);
 398        local_irq_restore(flags);
 399
 400        if (fifosize == 0)
 401                fifosize = 1;
 402
 403        return fifosize;
 404}
 405
 406static void apbuart_flush_fifo(struct uart_port *port)
 407{
 408        int i;
 409
 410        for (i = 0; i < port->fifosize; i++)
 411                UART_GET_CHAR(port);
 412}
 413
 414
 415/* ======================================================================== */
 416/* Console driver, if enabled                                               */
 417/* ======================================================================== */
 418
 419#ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
 420
 421static void apbuart_console_putchar(struct uart_port *port, int ch)
 422{
 423        unsigned int status;
 424        do {
 425                status = UART_GET_STATUS(port);
 426        } while (!UART_TX_READY(status));
 427        UART_PUT_CHAR(port, ch);
 428}
 429
 430static void
 431apbuart_console_write(struct console *co, const char *s, unsigned int count)
 432{
 433        struct uart_port *port = &grlib_apbuart_ports[co->index];
 434        unsigned int status, old_cr, new_cr;
 435
 436        /* First save the CR then disable the interrupts */
 437        old_cr = UART_GET_CTRL(port);
 438        new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
 439        UART_PUT_CTRL(port, new_cr);
 440
 441        uart_console_write(port, s, count, apbuart_console_putchar);
 442
 443        /*
 444         *      Finally, wait for transmitter to become empty
 445         *      and restore the TCR
 446         */
 447        do {
 448                status = UART_GET_STATUS(port);
 449        } while (!UART_TX_READY(status));
 450        UART_PUT_CTRL(port, old_cr);
 451}
 452
 453static void __init
 454apbuart_console_get_options(struct uart_port *port, int *baud,
 455                            int *parity, int *bits)
 456{
 457        if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
 458
 459                unsigned int quot, status;
 460                status = UART_GET_STATUS(port);
 461
 462                *parity = 'n';
 463                if (status & UART_CTRL_PE) {
 464                        if ((status & UART_CTRL_PS) == 0)
 465                                *parity = 'e';
 466                        else
 467                                *parity = 'o';
 468                }
 469
 470                *bits = 8;
 471                quot = UART_GET_SCAL(port) / 8;
 472                *baud = port->uartclk / (16 * (quot + 1));
 473        }
 474}
 475
 476static int __init apbuart_console_setup(struct console *co, char *options)
 477{
 478        struct uart_port *port;
 479        int baud = 38400;
 480        int bits = 8;
 481        int parity = 'n';
 482        int flow = 'n';
 483
 484        pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
 485                 co, co->index, options);
 486
 487        /*
 488         * Check whether an invalid uart number has been specified, and
 489         * if so, search for the first available port that does have
 490         * console support.
 491         */
 492        if (co->index >= grlib_apbuart_port_nr)
 493                co->index = 0;
 494
 495        port = &grlib_apbuart_ports[co->index];
 496
 497        spin_lock_init(&port->lock);
 498
 499        if (options)
 500                uart_parse_options(options, &baud, &parity, &bits, &flow);
 501        else
 502                apbuart_console_get_options(port, &baud, &parity, &bits);
 503
 504        return uart_set_options(port, co, baud, parity, bits, flow);
 505}
 506
 507static struct uart_driver grlib_apbuart_driver;
 508
 509static struct console grlib_apbuart_console = {
 510        .name = "ttyS",
 511        .write = apbuart_console_write,
 512        .device = uart_console_device,
 513        .setup = apbuart_console_setup,
 514        .flags = CON_PRINTBUFFER,
 515        .index = -1,
 516        .data = &grlib_apbuart_driver,
 517};
 518
 519
 520static int grlib_apbuart_configure(void);
 521
 522static int __init apbuart_console_init(void)
 523{
 524        if (grlib_apbuart_configure())
 525                return -ENODEV;
 526        register_console(&grlib_apbuart_console);
 527        return 0;
 528}
 529
 530console_initcall(apbuart_console_init);
 531
 532#define APBUART_CONSOLE (&grlib_apbuart_console)
 533#else
 534#define APBUART_CONSOLE NULL
 535#endif
 536
 537static struct uart_driver grlib_apbuart_driver = {
 538        .owner = THIS_MODULE,
 539        .driver_name = "serial",
 540        .dev_name = "ttyS",
 541        .major = SERIAL_APBUART_MAJOR,
 542        .minor = SERIAL_APBUART_MINOR,
 543        .nr = UART_NR,
 544        .cons = APBUART_CONSOLE,
 545};
 546
 547
 548/* ======================================================================== */
 549/* OF Platform Driver                                                       */
 550/* ======================================================================== */
 551
 552static int apbuart_probe(struct platform_device *op)
 553{
 554        int i;
 555        struct uart_port *port = NULL;
 556
 557        for (i = 0; i < grlib_apbuart_port_nr; i++) {
 558                if (op->dev.of_node == grlib_apbuart_nodes[i])
 559                        break;
 560        }
 561
 562        port = &grlib_apbuart_ports[i];
 563        port->dev = &op->dev;
 564        port->irq = op->archdata.irqs[0];
 565
 566        uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
 567
 568        apbuart_flush_fifo((struct uart_port *) port);
 569
 570        printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
 571               (unsigned long long) port->mapbase, port->irq);
 572        return 0;
 573}
 574
 575static const struct of_device_id apbuart_match[] = {
 576        {
 577         .name = "GAISLER_APBUART",
 578         },
 579        {
 580         .name = "01_00c",
 581         },
 582        {},
 583};
 584MODULE_DEVICE_TABLE(of, apbuart_match);
 585
 586static struct platform_driver grlib_apbuart_of_driver = {
 587        .probe = apbuart_probe,
 588        .driver = {
 589                .name = "grlib-apbuart",
 590                .of_match_table = apbuart_match,
 591        },
 592};
 593
 594
 595static int __init grlib_apbuart_configure(void)
 596{
 597        struct device_node *np;
 598        int line = 0;
 599
 600        for_each_matching_node(np, apbuart_match) {
 601                const int *ampopts;
 602                const u32 *freq_hz;
 603                const struct amba_prom_registers *regs;
 604                struct uart_port *port;
 605                unsigned long addr;
 606
 607                ampopts = of_get_property(np, "ampopts", NULL);
 608                if (ampopts && (*ampopts == 0))
 609                        continue; /* Ignore if used by another OS instance */
 610                regs = of_get_property(np, "reg", NULL);
 611                /* Frequency of APB Bus is frequency of UART */
 612                freq_hz = of_get_property(np, "freq", NULL);
 613
 614                if (!regs || !freq_hz || (*freq_hz == 0))
 615                        continue;
 616
 617                grlib_apbuart_nodes[line] = np;
 618
 619                addr = regs->phys_addr;
 620
 621                port = &grlib_apbuart_ports[line];
 622
 623                port->mapbase = addr;
 624                port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
 625                port->irq = 0;
 626                port->iotype = UPIO_MEM;
 627                port->ops = &grlib_apbuart_ops;
 628                port->flags = UPF_BOOT_AUTOCONF;
 629                port->line = line;
 630                port->uartclk = *freq_hz;
 631                port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
 632                line++;
 633
 634                /* We support maximum UART_NR uarts ... */
 635                if (line == UART_NR)
 636                        break;
 637        }
 638
 639        grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
 640        return line ? 0 : -ENODEV;
 641}
 642
 643static int __init grlib_apbuart_init(void)
 644{
 645        int ret;
 646
 647        /* Find all APBUARTS in device the tree and initialize their ports */
 648        ret = grlib_apbuart_configure();
 649        if (ret)
 650                return ret;
 651
 652        printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
 653
 654        ret = uart_register_driver(&grlib_apbuart_driver);
 655
 656        if (ret) {
 657                printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
 658                       __FILE__, ret);
 659                return ret;
 660        }
 661
 662        ret = platform_driver_register(&grlib_apbuart_of_driver);
 663        if (ret) {
 664                printk(KERN_ERR
 665                       "%s: platform_driver_register failed (%i)\n",
 666                       __FILE__, ret);
 667                uart_unregister_driver(&grlib_apbuart_driver);
 668                return ret;
 669        }
 670
 671        return ret;
 672}
 673
 674static void __exit grlib_apbuart_exit(void)
 675{
 676        int i;
 677
 678        for (i = 0; i < grlib_apbuart_port_nr; i++)
 679                uart_remove_one_port(&grlib_apbuart_driver,
 680                                     &grlib_apbuart_ports[i]);
 681
 682        uart_unregister_driver(&grlib_apbuart_driver);
 683        platform_driver_unregister(&grlib_apbuart_of_driver);
 684}
 685
 686module_init(grlib_apbuart_init);
 687module_exit(grlib_apbuart_exit);
 688
 689MODULE_AUTHOR("Aeroflex Gaisler AB");
 690MODULE_DESCRIPTION("GRLIB APBUART serial driver");
 691MODULE_VERSION("2.1");
 692MODULE_LICENSE("GPL");
 693
Hosted by Missing Link Electronics. The original LXR software by the LXR community, this experimental version by lxr@linux.no.