LXR linux/drivers/tty/serial/apbuart.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  Driver for GRLIB serial ports (APBUART)
   4 *
   5 *  Based on linux/drivers/serial/amba.c
   6 *
   7 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
   8 *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
   9 *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
  10 *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
  11 *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
  12 */
  13
  14#if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
  15#define SUPPORT_SYSRQ
  16#endif
  17
  18#include <linux/module.h>
  19#include <linux/tty.h>
  20#include <linux/tty_flip.h>
  21#include <linux/ioport.h>
  22#include <linux/init.h>
  23#include <linux/serial.h>
  24#include <linux/console.h>
  25#include <linux/sysrq.h>
  26#include <linux/kthread.h>
  27#include <linux/device.h>
  28#include <linux/of.h>
  29#include <linux/of_device.h>
  30#include <linux/of_platform.h>
  31#include <linux/of_irq.h>
  32#include <linux/platform_device.h>
  33#include <linux/io.h>
  34#include <linux/serial_core.h>
  35#include <asm/irq.h>
  36
  37#include "apbuart.h"
  38
  39#define SERIAL_APBUART_MAJOR    TTY_MAJOR
  40#define SERIAL_APBUART_MINOR    64
  41#define UART_DUMMY_RSR_RX       0x8000  /* for ignore all read */
  42
  43static void apbuart_tx_chars(struct uart_port *port);
  44
  45static void apbuart_stop_tx(struct uart_port *port)
  46{
  47        unsigned int cr;
  48
  49        cr = UART_GET_CTRL(port);
  50        cr &= ~UART_CTRL_TI;
  51        UART_PUT_CTRL(port, cr);
  52}
  53
  54static void apbuart_start_tx(struct uart_port *port)
  55{
  56        unsigned int cr;
  57
  58        cr = UART_GET_CTRL(port);
  59        cr |= UART_CTRL_TI;
  60        UART_PUT_CTRL(port, cr);
  61
  62        if (UART_GET_STATUS(port) & UART_STATUS_THE)
  63                apbuart_tx_chars(port);
  64}
  65
  66static void apbuart_stop_rx(struct uart_port *port)
  67{
  68        unsigned int cr;
  69
  70        cr = UART_GET_CTRL(port);
  71        cr &= ~(UART_CTRL_RI);
  72        UART_PUT_CTRL(port, cr);
  73}
  74
  75static void apbuart_rx_chars(struct uart_port *port)
  76{
  77        unsigned int status, ch, rsr, flag;
  78        unsigned int max_chars = port->fifosize;
  79
  80        status = UART_GET_STATUS(port);
  81
  82        while (UART_RX_DATA(status) && (max_chars--)) {
  83
  84                ch = UART_GET_CHAR(port);
  85                flag = TTY_NORMAL;
  86
  87                port->icount.rx++;
  88
  89                rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
  90                UART_PUT_STATUS(port, 0);
  91                if (rsr & UART_STATUS_ERR) {
  92
  93                        if (rsr & UART_STATUS_BR) {
  94                                rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
  95                                port->icount.brk++;
  96                                if (uart_handle_break(port))
  97                                        goto ignore_char;
  98                        } else if (rsr & UART_STATUS_PE) {
  99                                port->icount.parity++;
 100                        } else if (rsr & UART_STATUS_FE) {
 101                                port->icount.frame++;
 102                        }
 103                        if (rsr & UART_STATUS_OE)
 104                                port->icount.overrun++;
 105
 106                        rsr &= port->read_status_mask;
 107
 108                        if (rsr & UART_STATUS_PE)
 109                                flag = TTY_PARITY;
 110                        else if (rsr & UART_STATUS_FE)
 111                                flag = TTY_FRAME;
 112                }
 113
 114                if (uart_handle_sysrq_char(port, ch))
 115                        goto ignore_char;
 116
 117                uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
 118
 119
 120              ignore_char:
 121                status = UART_GET_STATUS(port);
 122        }
 123
 124        spin_unlock(&port->lock);
 125        tty_flip_buffer_push(&port->state->port);
 126        spin_lock(&port->lock);
 127}
 128
 129static void apbuart_tx_chars(struct uart_port *port)
 130{
 131        struct circ_buf *xmit = &port->state->xmit;
 132        int count;
 133
 134        if (port->x_char) {
 135                UART_PUT_CHAR(port, port->x_char);
 136                port->icount.tx++;
 137                port->x_char = 0;
 138                return;
 139        }
 140
 141        if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 142                apbuart_stop_tx(port);
 143                return;
 144        }
 145
 146        /* amba: fill FIFO */
 147        count = port->fifosize >> 1;
 148        do {
 149                UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 150                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 151                port->icount.tx++;
 152                if (uart_circ_empty(xmit))
 153                        break;
 154        } while (--count > 0);
 155
 156        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 157                uart_write_wakeup(port);
 158
 159        if (uart_circ_empty(xmit))
 160                apbuart_stop_tx(port);
 161}
 162
 163static irqreturn_t apbuart_int(int irq, void *dev_id)
 164{
 165        struct uart_port *port = dev_id;
 166        unsigned int status;
 167
 168        spin_lock(&port->lock);
 169
 170        status = UART_GET_STATUS(port);
 171        if (status & UART_STATUS_DR)
 172                apbuart_rx_chars(port);
 173        if (status & UART_STATUS_THE)
 174                apbuart_tx_chars(port);
 175
 176        spin_unlock(&port->lock);
 177
 178        return IRQ_HANDLED;
 179}
 180
 181static unsigned int apbuart_tx_empty(struct uart_port *port)
 182{
 183        unsigned int status = UART_GET_STATUS(port);
 184        return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
 185}
 186
 187static unsigned int apbuart_get_mctrl(struct uart_port *port)
 188{
 189        /* The GRLIB APBUART handles flow control in hardware */
 190        return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 191}
 192
 193static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 194{
 195        /* The GRLIB APBUART handles flow control in hardware */
 196}
 197
 198static void apbuart_break_ctl(struct uart_port *port, int break_state)
 199{
 200        /* We don't support sending break */
 201}
 202
 203static int apbuart_startup(struct uart_port *port)
 204{
 205        int retval;
 206        unsigned int cr;
 207
 208        /* Allocate the IRQ */
 209        retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
 210        if (retval)
 211                return retval;
 212
 213        /* Finally, enable interrupts */
 214        cr = UART_GET_CTRL(port);
 215        UART_PUT_CTRL(port,
 216                      cr | UART_CTRL_RE | UART_CTRL_TE |
 217                      UART_CTRL_RI | UART_CTRL_TI);
 218
 219        return 0;
 220}
 221
 222static void apbuart_shutdown(struct uart_port *port)
 223{
 224        unsigned int cr;
 225
 226        /* disable all interrupts, disable the port */
 227        cr = UART_GET_CTRL(port);
 228        UART_PUT_CTRL(port,
 229                      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
 230                             UART_CTRL_RI | UART_CTRL_TI));
 231
 232        /* Free the interrupt */
 233        free_irq(port->irq, port);
 234}
 235
 236static void apbuart_set_termios(struct uart_port *port,
 237                                struct ktermios *termios, struct ktermios *old)
 238{
 239        unsigned int cr;
 240        unsigned long flags;
 241        unsigned int baud, quot;
 242
 243        /* Ask the core to calculate the divisor for us. */
 244        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 245        if (baud == 0)
 246                panic("invalid baudrate %i\n", port->uartclk / 16);
 247
 248        /* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
 249        quot = (uart_get_divisor(port, baud)) * 2;
 250        cr = UART_GET_CTRL(port);
 251        cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
 252
 253        if (termios->c_cflag & PARENB) {
 254                cr |= UART_CTRL_PE;
 255                if ((termios->c_cflag & PARODD))
 256                        cr |= UART_CTRL_PS;
 257        }
 258
 259        /* Enable flow control. */
 260        if (termios->c_cflag & CRTSCTS)
 261                cr |= UART_CTRL_FL;
 262
 263        spin_lock_irqsave(&port->lock, flags);
 264
 265        /* Update the per-port timeout. */
 266        uart_update_timeout(port, termios->c_cflag, baud);
 267
 268        port->read_status_mask = UART_STATUS_OE;
 269        if (termios->c_iflag & INPCK)
 270                port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 271
 272        /* Characters to ignore */
 273        port->ignore_status_mask = 0;
 274        if (termios->c_iflag & IGNPAR)
 275                port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 276
 277        /* Ignore all characters if CREAD is not set. */
 278        if ((termios->c_cflag & CREAD) == 0)
 279                port->ignore_status_mask |= UART_DUMMY_RSR_RX;
 280
 281        /* Set baud rate */
 282        quot -= 1;
 283        UART_PUT_SCAL(port, quot);
 284        UART_PUT_CTRL(port, cr);
 285
 286        spin_unlock_irqrestore(&port->lock, flags);
 287}
 288
 289static const char *apbuart_type(struct uart_port *port)
 290{
 291        return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
 292}
 293
 294static void apbuart_release_port(struct uart_port *port)
 295{
 296        release_mem_region(port->mapbase, 0x100);
 297}
 298
 299static int apbuart_request_port(struct uart_port *port)
 300{
 301        return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
 302            != NULL ? 0 : -EBUSY;
 303        return 0;
 304}
 305
 306/* Configure/autoconfigure the port */
 307static void apbuart_config_port(struct uart_port *port, int flags)
 308{
 309        if (flags & UART_CONFIG_TYPE) {
 310                port->type = PORT_APBUART;
 311                apbuart_request_port(port);
 312        }
 313}
 314
 315/* Verify the new serial_struct (for TIOCSSERIAL) */
 316static int apbuart_verify_port(struct uart_port *port,
 317                               struct serial_struct *ser)
 318{
 319        int ret = 0;
 320        if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
 321                ret = -EINVAL;
 322        if (ser->irq < 0 || ser->irq >= NR_IRQS)
 323                ret = -EINVAL;
 324        if (ser->baud_base < 9600)
 325                ret = -EINVAL;
 326        return ret;
 327}
 328
 329static const struct uart_ops grlib_apbuart_ops = {
 330        .tx_empty = apbuart_tx_empty,
 331        .set_mctrl = apbuart_set_mctrl,
 332        .get_mctrl = apbuart_get_mctrl,
 333        .stop_tx = apbuart_stop_tx,
 334        .start_tx = apbuart_start_tx,
 335        .stop_rx = apbuart_stop_rx,
 336        .break_ctl = apbuart_break_ctl,
 337        .startup = apbuart_startup,
 338        .shutdown = apbuart_shutdown,
 339        .set_termios = apbuart_set_termios,
 340        .type = apbuart_type,
 341        .release_port = apbuart_release_port,
 342        .request_port = apbuart_request_port,
 343        .config_port = apbuart_config_port,
 344        .verify_port = apbuart_verify_port,
 345};
 346
 347static struct uart_port grlib_apbuart_ports[UART_NR];
 348static struct device_node *grlib_apbuart_nodes[UART_NR];
 349
 350static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
 351{
 352        int ctrl, loop = 0;
 353        int status;
 354        int fifosize;
 355        unsigned long flags;
 356
 357        ctrl = UART_GET_CTRL(port);
 358
 359        /*
 360         * Enable the transceiver and wait for it to be ready to send data.
 361         * Clear interrupts so that this process will not be externally
 362         * interrupted in the middle (which can cause the transceiver to
 363         * drain prematurely).
 364         */
 365
 366        local_irq_save(flags);
 367
 368        UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
 369
 370        while (!UART_TX_READY(UART_GET_STATUS(port)))
 371                loop++;
 372
 373        /*
 374         * Disable the transceiver so data isn't actually sent during the
 375         * actual test.
 376         */
 377
 378        UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
 379
 380        fifosize = 1;
 381        UART_PUT_CHAR(port, 0);
 382
 383        /*
 384         * So long as transmitting a character increments the tranceivier FIFO
 385         * length the FIFO must be at least that big. These bytes will
 386         * automatically drain off of the FIFO.
 387         */
 388
 389        status = UART_GET_STATUS(port);
 390        while (((status >> 20) & 0x3F) == fifosize) {
 391                fifosize++;
 392                UART_PUT_CHAR(port, 0);
 393                status = UART_GET_STATUS(port);
 394        }
 395
 396        fifosize--;
 397
 398        UART_PUT_CTRL(port, ctrl);
 399        local_irq_restore(flags);
 400
 401        if (fifosize == 0)
 402                fifosize = 1;
 403
 404        return fifosize;
 405}
 406
 407static void apbuart_flush_fifo(struct uart_port *port)
 408{
 409        int i;
 410
 411        for (i = 0; i < port->fifosize; i++)
 412                UART_GET_CHAR(port);
 413}
 414
 415
 416/* ======================================================================== */
 417/* Console driver, if enabled                                               */
 418/* ======================================================================== */
 419
 420#ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
 421
 422static void apbuart_console_putchar(struct uart_port *port, int ch)
 423{
 424        unsigned int status;
 425        do {
 426                status = UART_GET_STATUS(port);
 427        } while (!UART_TX_READY(status));
 428        UART_PUT_CHAR(port, ch);
 429}
 430
 431static void
 432apbuart_console_write(struct console *co, const char *s, unsigned int count)
 433{
 434        struct uart_port *port = &grlib_apbuart_ports[co->index];
 435        unsigned int status, old_cr, new_cr;
 436
 437        /* First save the CR then disable the interrupts */
 438        old_cr = UART_GET_CTRL(port);
 439        new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
 440        UART_PUT_CTRL(port, new_cr);
 441
 442        uart_console_write(port, s, count, apbuart_console_putchar);
 443
 444        /*
 445         *      Finally, wait for transmitter to become empty
 446         *      and restore the TCR
 447         */
 448        do {
 449                status = UART_GET_STATUS(port);
 450        } while (!UART_TX_READY(status));
 451        UART_PUT_CTRL(port, old_cr);
 452}
 453
 454static void __init
 455apbuart_console_get_options(struct uart_port *port, int *baud,
 456                            int *parity, int *bits)
 457{
 458        if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
 459
 460                unsigned int quot, status;
 461                status = UART_GET_STATUS(port);
 462
 463                *parity = 'n';
 464                if (status & UART_CTRL_PE) {
 465                        if ((status & UART_CTRL_PS) == 0)
 466                                *parity = 'e';
 467                        else
 468                                *parity = 'o';
 469                }
 470
 471                *bits = 8;
 472                quot = UART_GET_SCAL(port) / 8;
 473                *baud = port->uartclk / (16 * (quot + 1));
 474        }
 475}
 476
 477static int __init apbuart_console_setup(struct console *co, char *options)
 478{
 479        struct uart_port *port;
 480        int baud = 38400;
 481        int bits = 8;
 482        int parity = 'n';
 483        int flow = 'n';
 484
 485        pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
 486                 co, co->index, options);
 487
 488        /*
 489         * Check whether an invalid uart number has been specified, and
 490         * if so, search for the first available port that does have
 491         * console support.
 492         */
 493        if (co->index >= grlib_apbuart_port_nr)
 494                co->index = 0;
 495
 496        port = &grlib_apbuart_ports[co->index];
 497
 498        spin_lock_init(&port->lock);
 499
 500        if (options)
 501                uart_parse_options(options, &baud, &parity, &bits, &flow);
 502        else
 503                apbuart_console_get_options(port, &baud, &parity, &bits);
 504
 505        return uart_set_options(port, co, baud, parity, bits, flow);
 506}
 507
 508static struct uart_driver grlib_apbuart_driver;
 509
 510static struct console grlib_apbuart_console = {
 511        .name = "ttyS",
 512        .write = apbuart_console_write,
 513        .device = uart_console_device,
 514        .setup = apbuart_console_setup,
 515        .flags = CON_PRINTBUFFER,
 516        .index = -1,
 517        .data = &grlib_apbuart_driver,
 518};
 519
 520
 521static int grlib_apbuart_configure(void);
 522
 523static int __init apbuart_console_init(void)
 524{
 525        if (grlib_apbuart_configure())
 526                return -ENODEV;
 527        register_console(&grlib_apbuart_console);
 528        return 0;
 529}
 530
 531console_initcall(apbuart_console_init);
 532
 533#define APBUART_CONSOLE (&grlib_apbuart_console)
 534#else
 535#define APBUART_CONSOLE NULL
 536#endif
 537
 538static struct uart_driver grlib_apbuart_driver = {
 539        .owner = THIS_MODULE,
 540        .driver_name = "serial",
 541        .dev_name = "ttyS",
 542        .major = SERIAL_APBUART_MAJOR,
 543        .minor = SERIAL_APBUART_MINOR,
 544        .nr = UART_NR,
 545        .cons = APBUART_CONSOLE,
 546};
 547
 548
 549/* ======================================================================== */
 550/* OF Platform Driver                                                       */
 551/* ======================================================================== */
 552
 553static int apbuart_probe(struct platform_device *op)
 554{
 555        int i;
 556        struct uart_port *port = NULL;
 557
 558        for (i = 0; i < grlib_apbuart_port_nr; i++) {
 559                if (op->dev.of_node == grlib_apbuart_nodes[i])
 560                        break;
 561        }
 562
 563        port = &grlib_apbuart_ports[i];
 564        port->dev = &op->dev;
 565        port->irq = op->archdata.irqs[0];
 566
 567        uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
 568
 569        apbuart_flush_fifo((struct uart_port *) port);
 570
 571        printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
 572               (unsigned long long) port->mapbase, port->irq);
 573        return 0;
 574}
 575
 576static const struct of_device_id apbuart_match[] = {
 577        {
 578         .name = "GAISLER_APBUART",
 579         },
 580        {
 581         .name = "01_00c",
 582         },
 583        {},
 584};
 585MODULE_DEVICE_TABLE(of, apbuart_match);
 586
 587static struct platform_driver grlib_apbuart_of_driver = {
 588        .probe = apbuart_probe,
 589        .driver = {
 590                .name = "grlib-apbuart",
 591                .of_match_table = apbuart_match,
 592        },
 593};
 594
 595
 596static int __init grlib_apbuart_configure(void)
 597{
 598        struct device_node *np;
 599        int line = 0;
 600
 601        for_each_matching_node(np, apbuart_match) {
 602                const int *ampopts;
 603                const u32 *freq_hz;
 604                const struct amba_prom_registers *regs;
 605                struct uart_port *port;
 606                unsigned long addr;
 607
 608                ampopts = of_get_property(np, "ampopts", NULL);
 609                if (ampopts && (*ampopts == 0))
 610                        continue; /* Ignore if used by another OS instance */
 611                regs = of_get_property(np, "reg", NULL);
 612                /* Frequency of APB Bus is frequency of UART */
 613                freq_hz = of_get_property(np, "freq", NULL);
 614
 615                if (!regs || !freq_hz || (*freq_hz == 0))
 616                        continue;
 617
 618                grlib_apbuart_nodes[line] = np;
 619
 620                addr = regs->phys_addr;
 621
 622                port = &grlib_apbuart_ports[line];
 623
 624                port->mapbase = addr;
 625                port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
 626                port->irq = 0;
 627                port->iotype = UPIO_MEM;
 628                port->ops = &grlib_apbuart_ops;
 629                port->flags = UPF_BOOT_AUTOCONF;
 630                port->line = line;
 631                port->uartclk = *freq_hz;
 632                port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
 633                line++;
 634
 635                /* We support maximum UART_NR uarts ... */
 636                if (line == UART_NR)
 637                        break;
 638        }
 639
 640        grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
 641        return line ? 0 : -ENODEV;
 642}
 643
 644static int __init grlib_apbuart_init(void)
 645{
 646        int ret;
 647
 648        /* Find all APBUARTS in device the tree and initialize their ports */
 649        ret = grlib_apbuart_configure();
 650        if (ret)
 651                return ret;
 652
 653        printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
 654
 655        ret = uart_register_driver(&grlib_apbuart_driver);
 656
 657        if (ret) {
 658                printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
 659                       __FILE__, ret);
 660                return ret;
 661        }
 662
 663        ret = platform_driver_register(&grlib_apbuart_of_driver);
 664        if (ret) {
 665                printk(KERN_ERR
 666                       "%s: platform_driver_register failed (%i)\n",
 667                       __FILE__, ret);
 668                uart_unregister_driver(&grlib_apbuart_driver);
 669                return ret;
 670        }
 671
 672        return ret;
 673}
 674
 675static void __exit grlib_apbuart_exit(void)
 676{
 677        int i;
 678
 679        for (i = 0; i < grlib_apbuart_port_nr; i++)
 680                uart_remove_one_port(&grlib_apbuart_driver,
 681                                     &grlib_apbuart_ports[i]);
 682
 683        uart_unregister_driver(&grlib_apbuart_driver);
 684        platform_driver_unregister(&grlib_apbuart_of_driver);
 685}
 686
 687module_init(grlib_apbuart_init);
 688module_exit(grlib_apbuart_exit);
 689
 690MODULE_AUTHOR("Aeroflex Gaisler AB");
 691MODULE_DESCRIPTION("GRLIB APBUART serial driver");
 692MODULE_VERSION("2.1");
 693MODULE_LICENSE("GPL");
 694