drivers/serial/uartlite.c

   1 /*
   2  * uartlite.c: Serial driver for Xilinx uartlite serial controller
   3  *
   4  * Copyright (C) 2006 Peter Korsgaard <jacmet@sunsite.dk>
   5  * Copyright (C) 2007 Secret Lab Technologies Ltd.
   6  *
   7  * This file is licensed under the terms of the GNU General Public License
   8  * version 2.  This program is licensed "as is" without any warranty of any
   9  * kind, whether express or implied.
  10  */
  11
  12 #include <linux/platform_device.h>
  13 #include <linux/module.h>
  14 #include <linux/console.h>
  15 #include <linux/serial.h>
  16 #include <linux/serial_core.h>
  17 #include <linux/tty.h>
  18 #include <linux/delay.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/init.h>
  21 #include <asm/io.h>
  22 #if defined(CONFIG_OF)
  23 #include <linux/of.h>
  24 #include <linux/of_device.h>
  25 #include <linux/of_platform.h>
  26
  27 /* Match table for of_platform binding */
  28 static struct of_device_id ulite_of_match[] __devinitdata = {
  29         { .compatible = "xlnx,opb-uartlite-1.00.b", },
  30         { .compatible = "xlnx,xps-uartlite-1.00.a", },
  31         {}
  32 };
  33 MODULE_DEVICE_TABLE(of, ulite_of_match);
  34
  35 #endif
  36
  37 #define ULITE_NAME              "ttyUL"
  38 #define ULITE_MAJOR             204
  39 #define ULITE_MINOR             187
  40 #define ULITE_NR_UARTS          4
  41
  42 /* ---------------------------------------------------------------------
  43  * Register definitions
  44  *
  45  * For register details see datasheet:
  46  * http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
  47  */
  48
  49 #define ULITE_RX                0x00
  50 #define ULITE_TX                0x04
  51 #define ULITE_STATUS            0x08
  52 #define ULITE_CONTROL           0x0c
  53
  54 #define ULITE_REGION            16
  55
  56 #define ULITE_STATUS_RXVALID    0x01
  57 #define ULITE_STATUS_RXFULL     0x02
  58 #define ULITE_STATUS_TXEMPTY    0x04
  59 #define ULITE_STATUS_TXFULL     0x08
  60 #define ULITE_STATUS_IE         0x10
  61 #define ULITE_STATUS_OVERRUN    0x20
  62 #define ULITE_STATUS_FRAME      0x40
  63 #define ULITE_STATUS_PARITY     0x80
  64
  65 #define ULITE_CONTROL_RST_TX    0x01
  66 #define ULITE_CONTROL_RST_RX    0x02
  67 #define ULITE_CONTROL_IE        0x10
  68
  69
  70 static struct uart_port ulite_ports[ULITE_NR_UARTS];
  71
  72 /* ---------------------------------------------------------------------
  73  * Core UART driver operations
  74  */
  75
  76 static int ulite_receive(struct uart_port *port, int stat)
  77 {
  78         struct tty_struct *tty = port->state->port.tty;
  79         unsigned char ch = 0;
  80         char flag = TTY_NORMAL;
  81
  82         if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  83                      | ULITE_STATUS_FRAME)) == 0)
  84                 return 0;
  85
  86         /* stats */
  87         if (stat & ULITE_STATUS_RXVALID) {
  88                 port->icount.rx++;
  89                 ch = readb(port->membase + ULITE_RX);
  90
  91                 if (stat & ULITE_STATUS_PARITY)
  92                         port->icount.parity++;
  93         }
  94
  95         if (stat & ULITE_STATUS_OVERRUN)
  96                 port->icount.overrun++;
  97
  98         if (stat & ULITE_STATUS_FRAME)
  99                 port->icount.frame++;
 100
 101
 102         /* drop byte with parity error if IGNPAR specificed */
 103         if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
 104                 stat &= ~ULITE_STATUS_RXVALID;
 105
 106         stat &= port->read_status_mask;
 107
 108         if (stat & ULITE_STATUS_PARITY)
 109                 flag = TTY_PARITY;
 110
 111
 112         stat &= ~port->ignore_status_mask;
 113
 114         if (stat & ULITE_STATUS_RXVALID)
 115                 tty_insert_flip_char(tty, ch, flag);
 116
 117         if (stat & ULITE_STATUS_FRAME)
 118                 tty_insert_flip_char(tty, 0, TTY_FRAME);
 119
 120         if (stat & ULITE_STATUS_OVERRUN)
 121                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 122
 123         return 1;
 124 }
 125
 126 static int ulite_transmit(struct uart_port *port, int stat)
 127 {
 128         struct circ_buf *xmit  = &port->state->xmit;
 129
 130         if (stat & ULITE_STATUS_TXFULL)
 131                 return 0;
 132
 133         if (port->x_char) {
 134                 writeb(port->x_char, port->membase + ULITE_TX);
 135                 port->x_char = 0;
 136                 port->icount.tx++;
 137                 return 1;
 138         }
 139
 140         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 141                 return 0;
 142
 143         writeb(xmit->buf[xmit->tail], port->membase + ULITE_TX);
 144         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 145         port->icount.tx++;
 146
 147         /* wake up */
 148         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 149                 uart_write_wakeup(port);
 150
 151         return 1;
 152 }
 153
 154 static irqreturn_t ulite_isr(int irq, void *dev_id)
 155 {
 156         struct uart_port *port = dev_id;
 157         int busy, n = 0;
 158
 159         do {
 160                 int stat = readb(port->membase + ULITE_STATUS);
 161                 busy  = ulite_receive(port, stat);
 162                 busy |= ulite_transmit(port, stat);
 163                 n++;
 164         } while (busy);
 165
 166         /* work done? */
 167         if (n > 1) {
 168                 tty_flip_buffer_push(port->state->port.tty);
 169                 return IRQ_HANDLED;
 170         } else {
 171                 return IRQ_NONE;
 172         }
 173 }
 174
 175 static unsigned int ulite_tx_empty(struct uart_port *port)
 176 {
 177         unsigned long flags;
 178         unsigned int ret;
 179
 180         spin_lock_irqsave(&port->lock, flags);
 181         ret = readb(port->membase + ULITE_STATUS);
 182         spin_unlock_irqrestore(&port->lock, flags);
 183
 184         return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
 185 }
 186
 187 static unsigned int ulite_get_mctrl(struct uart_port *port)
 188 {
 189         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 190 }
 191
 192 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
 193 {
 194         /* N/A */
 195 }
 196
 197 static void ulite_stop_tx(struct uart_port *port)
 198 {
 199         /* N/A */
 200 }
 201
 202 static void ulite_start_tx(struct uart_port *port)
 203 {
 204         ulite_transmit(port, readb(port->membase + ULITE_STATUS));
 205 }
 206
 207 static void ulite_stop_rx(struct uart_port *port)
 208 {
 209         /* don't forward any more data (like !CREAD) */
 210         port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 211                 | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 212 }
 213
 214 static void ulite_enable_ms(struct uart_port *port)
 215 {
 216         /* N/A */
 217 }
 218
 219 static void ulite_break_ctl(struct uart_port *port, int ctl)
 220 {
 221         /* N/A */
 222 }
 223
 224 static int ulite_startup(struct uart_port *port)
 225 {
 226         int ret;
 227
 228         ret = request_irq(port->irq, ulite_isr,
 229                           IRQF_SHARED | IRQF_SAMPLE_RANDOM, "uartlite", port);
 230         if (ret)
 231                 return ret;
 232
 233         writeb(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
 234                port->membase + ULITE_CONTROL);
 235         writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 236
 237         return 0;
 238 }
 239
 240 static void ulite_shutdown(struct uart_port *port)
 241 {
 242         writeb(0, port->membase + ULITE_CONTROL);
 243         readb(port->membase + ULITE_CONTROL); /* dummy */
 244         free_irq(port->irq, port);
 245 }
 246
 247 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
 248                               struct ktermios *old)
 249 {
 250         unsigned long flags;
 251         unsigned int baud;
 252
 253         spin_lock_irqsave(&port->lock, flags);
 254
 255         port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 256                 | ULITE_STATUS_TXFULL;
 257
 258         if (termios->c_iflag & INPCK)
 259                 port->read_status_mask |=
 260                         ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
 261
 262         port->ignore_status_mask = 0;
 263         if (termios->c_iflag & IGNPAR)
 264                 port->ignore_status_mask |= ULITE_STATUS_PARITY
 265                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 266
 267         /* ignore all characters if CREAD is not set */
 268         if ((termios->c_cflag & CREAD) == 0)
 269                 port->ignore_status_mask |=
 270                         ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 271                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 272
 273         /* update timeout */
 274         baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 275         uart_update_timeout(port, termios->c_cflag, baud);
 276
 277         spin_unlock_irqrestore(&port->lock, flags);
 278 }
 279
 280 static const char *ulite_type(struct uart_port *port)
 281 {
 282         return port->type == PORT_UARTLITE ? "uartlite" : NULL;
 283 }
 284
 285 static void ulite_release_port(struct uart_port *port)
 286 {
 287         release_mem_region(port->mapbase, ULITE_REGION);
 288         iounmap(port->membase);
 289         port->membase = NULL;
 290 }
 291
 292 static int ulite_request_port(struct uart_port *port)
 293 {
 294         pr_debug("ulite console: port=%p; port->mapbase=%llx\n",
 295                  port, (unsigned long long) port->mapbase);
 296
 297         if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
 298                 dev_err(port->dev, "Memory region busy\n");
 299                 return -EBUSY;
 300         }
 301
 302         port->membase = ioremap(port->mapbase, ULITE_REGION);
 303         if (!port->membase) {
 304                 dev_err(port->dev, "Unable to map registers\n");
 305                 release_mem_region(port->mapbase, ULITE_REGION);
 306                 return -EBUSY;
 307         }
 308
 309         return 0;
 310 }
 311
 312 static void ulite_config_port(struct uart_port *port, int flags)
 313 {
 314         if (!ulite_request_port(port))
 315                 port->type = PORT_UARTLITE;
 316 }
 317
 318 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
 319 {
 320         /* we don't want the core code to modify any port params */
 321         return -EINVAL;
 322 }
 323
 324 static struct uart_ops ulite_ops = {
 325         .tx_empty       = ulite_tx_empty,
 326         .set_mctrl      = ulite_set_mctrl,
 327         .get_mctrl      = ulite_get_mctrl,
 328         .stop_tx        = ulite_stop_tx,
 329         .start_tx       = ulite_start_tx,
 330         .stop_rx        = ulite_stop_rx,
 331         .enable_ms      = ulite_enable_ms,
 332         .break_ctl      = ulite_break_ctl,
 333         .startup        = ulite_startup,
 334         .shutdown       = ulite_shutdown,
 335         .set_termios    = ulite_set_termios,
 336         .type           = ulite_type,
 337         .release_port   = ulite_release_port,
 338         .request_port   = ulite_request_port,
 339         .config_port    = ulite_config_port,
 340         .verify_port    = ulite_verify_port
 341 };
 342
 343 /* ---------------------------------------------------------------------
 344  * Console driver operations
 345  */
 346
 347 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 348 static void ulite_console_wait_tx(struct uart_port *port)
 349 {
 350         int i;
 351         u8 val;
 352
 353         /* Spin waiting for TX fifo to have space available */
 354         for (i = 0; i < 100000; i++) {
 355                 val = readb(port->membase + ULITE_STATUS);
 356                 if ((val & ULITE_STATUS_TXFULL) == 0)
 357                         break;
 358                 cpu_relax();
 359         }
 360 }
 361
 362 static void ulite_console_putchar(struct uart_port *port, int ch)
 363 {
 364         ulite_console_wait_tx(port);
 365         writeb(ch, port->membase + ULITE_TX);
 366 }
 367
 368 static void ulite_console_write(struct console *co, const char *s,
 369                                 unsigned int count)
 370 {
 371         struct uart_port *port = &ulite_ports[co->index];
 372         unsigned long flags;
 373         unsigned int ier;
 374         int locked = 1;
 375
 376         if (oops_in_progress) {
 377                 locked = spin_trylock_irqsave(&port->lock, flags);
 378         } else
 379                 spin_lock_irqsave(&port->lock, flags);
 380
 381         /* save and disable interrupt */
 382         ier = readb(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
 383         writeb(0, port->membase + ULITE_CONTROL);
 384
 385         uart_console_write(port, s, count, ulite_console_putchar);
 386
 387         ulite_console_wait_tx(port);
 388
 389         /* restore interrupt state */
 390         if (ier)
 391                 writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 392
 393         if (locked)
 394                 spin_unlock_irqrestore(&port->lock, flags);
 395 }
 396
 397 static int __devinit ulite_console_setup(struct console *co, char *options)
 398 {
 399         struct uart_port *port;
 400         int baud = 9600;
 401         int bits = 8;
 402         int parity = 'n';
 403         int flow = 'n';
 404
 405         if (co->index < 0 || co->index >= ULITE_NR_UARTS)
 406                 return -EINVAL;
 407
 408         port = &ulite_ports[co->index];
 409
 410         /* Has the device been initialized yet? */
 411         if (!port->mapbase) {
 412                 pr_debug("console on ttyUL%i not present\n", co->index);
 413                 return -ENODEV;
 414         }
 415
 416         /* not initialized yet? */
 417         if (!port->membase) {
 418                 if (ulite_request_port(port))
 419                         return -ENODEV;
 420         }
 421
 422         if (options)
 423                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 424
 425         return uart_set_options(port, co, baud, parity, bits, flow);
 426 }
 427
 428 static struct uart_driver ulite_uart_driver;
 429
 430 static struct console ulite_console = {
 431         .name   = ULITE_NAME,
 432         .write  = ulite_console_write,
 433         .device = uart_console_device,
 434         .setup  = ulite_console_setup,
 435         .flags  = CON_PRINTBUFFER,
 436         .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
 437         .data   = &ulite_uart_driver,
 438 };
 439
 440 static int __init ulite_console_init(void)
 441 {
 442         register_console(&ulite_console);
 443         return 0;
 444 }
 445
 446 console_initcall(ulite_console_init);
 447
 448 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
 449
 450 static struct uart_driver ulite_uart_driver = {
 451         .owner          = THIS_MODULE,
 452         .driver_name    = "uartlite",
 453         .dev_name       = ULITE_NAME,
 454         .major          = ULITE_MAJOR,
 455         .minor          = ULITE_MINOR,
 456         .nr             = ULITE_NR_UARTS,
 457 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 458         .cons           = &ulite_console,
 459 #endif
 460 };
 461
 462 /* ---------------------------------------------------------------------
 463  * Port assignment functions (mapping devices to uart_port structures)
 464  */
 465
 466 /** ulite_assign: register a uartlite device with the driver
 467  *
 468  * @dev: pointer to device structure
 469  * @id: requested id number.  Pass -1 for automatic port assignment
 470  * @base: base address of uartlite registers
 471  * @irq: irq number for uartlite
 472  *
 473  * Returns: 0 on success, <0 otherwise
 474  */
 475 static int __devinit ulite_assign(struct device *dev, int id, u32 base, int irq)
 476 {
 477         struct uart_port *port;
 478         int rc;
 479
 480         /* if id = -1; then scan for a free id and use that */
 481         if (id < 0) {
 482                 for (id = 0; id < ULITE_NR_UARTS; id++)
 483                         if (ulite_ports[id].mapbase == 0)
 484                                 break;
 485         }
 486         if (id < 0 || id >= ULITE_NR_UARTS) {
 487                 dev_err(dev, "%s%i too large\n", ULITE_NAME, id);
 488                 return -EINVAL;
 489         }
 490
 491         if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {
 492                 dev_err(dev, "cannot assign to %s%i; it is already in use\n",
 493                         ULITE_NAME, id);
 494                 return -EBUSY;
 495         }
 496
 497         port = &ulite_ports[id];
 498
 499         spin_lock_init(&port->lock);
 500         port->fifosize = 16;
 501         port->regshift = 2;
 502         port->iotype = UPIO_MEM;
 503         port->iobase = 1; /* mark port in use */
 504         port->mapbase = base;
 505         port->membase = NULL;
 506         port->ops = &ulite_ops;
 507         port->irq = irq;
 508         port->flags = UPF_BOOT_AUTOCONF;
 509         port->dev = dev;
 510         port->type = PORT_UNKNOWN;
 511         port->line = id;
 512
 513         dev_set_drvdata(dev, port);
 514
 515         /* Register the port */
 516         rc = uart_add_one_port(&ulite_uart_driver, port);
 517         if (rc) {
 518                 dev_err(dev, "uart_add_one_port() failed; err=%i\n", rc);
 519                 port->mapbase = 0;
 520                 dev_set_drvdata(dev, NULL);
 521                 return rc;
 522         }
 523
 524         return 0;
 525 }
 526
 527 /** ulite_release: register a uartlite device with the driver
 528  *
 529  * @dev: pointer to device structure
 530  */
 531 static int __devexit ulite_release(struct device *dev)
 532 {
 533         struct uart_port *port = dev_get_drvdata(dev);
 534         int rc = 0;
 535
 536         if (port) {
 537                 rc = uart_remove_one_port(&ulite_uart_driver, port);
 538                 dev_set_drvdata(dev, NULL);
 539                 port->mapbase = 0;
 540         }
 541
 542         return rc;
 543 }
 544
 545 /* ---------------------------------------------------------------------
 546  * Platform bus binding
 547  */
 548
 549 static int __devinit ulite_probe(struct platform_device *pdev)
 550 {
 551         struct resource *res, *res2;
 552
 553         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 554         if (!res)
 555                 return -ENODEV;
 556
 557         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 558         if (!res2)
 559                 return -ENODEV;
 560
 561         return ulite_assign(&pdev->dev, pdev->id, res->start, res2->start);
 562 }
 563
 564 static int __devexit ulite_remove(struct platform_device *pdev)
 565 {
 566         return ulite_release(&pdev->dev);
 567 }
 568
 569 /* work with hotplug and coldplug */
 570 MODULE_ALIAS("platform:uartlite");
 571
 572 static struct platform_driver ulite_platform_driver = {
 573         .probe  = ulite_probe,
 574         .remove = __devexit_p(ulite_remove),
 575         .driver = {
 576                    .owner = THIS_MODULE,
 577                    .name  = "uartlite",
 578                    },
 579 };
 580
 581 /* ---------------------------------------------------------------------
 582  * OF bus bindings
 583  */
 584 #if defined(CONFIG_OF)
 585 static int __devinit
 586 ulite_of_probe(struct of_device *op, const struct of_device_id *match)
 587 {
 588         struct resource res;
 589         const unsigned int *id;
 590         int irq, rc;
 591
 592         dev_dbg(&op->dev, "%s(%p, %p)\n", __func__, op, match);
 593
 594         rc = of_address_to_resource(op->node, 0, &res);
 595         if (rc) {
 596                 dev_err(&op->dev, "invalid address\n");
 597                 return rc;
 598         }
 599
 600         irq = irq_of_parse_and_map(op->node, 0);
 601
 602         id = of_get_property(op->node, "port-number", NULL);
 603
 604         return ulite_assign(&op->dev, id ? *id : -1, res.start+3, irq);
 605 }
 606
 607 static int __devexit ulite_of_remove(struct of_device *op)
 608 {
 609         return ulite_release(&op->dev);
 610 }
 611
 612 static struct of_platform_driver ulite_of_driver = {
 613         .owner = THIS_MODULE,
 614         .name = "uartlite",
 615         .match_table = ulite_of_match,
 616         .probe = ulite_of_probe,
 617         .remove = __devexit_p(ulite_of_remove),
 618         .driver = {
 619                 .name = "uartlite",
 620         },
 621 };
 622
 623 /* Registration helpers to keep the number of #ifdefs to a minimum */
 624 static inline int __init ulite_of_register(void)
 625 {
 626         pr_debug("uartlite: calling of_register_platform_driver()\n");
 627         return of_register_platform_driver(&ulite_of_driver);
 628 }
 629
 630 static inline void __exit ulite_of_unregister(void)
 631 {
 632         of_unregister_platform_driver(&ulite_of_driver);
 633 }
 634 #else /* CONFIG_OF */
 635 /* CONFIG_OF not enabled; do nothing helpers */
 636 static inline int __init ulite_of_register(void) { return 0; }
 637 static inline void __exit ulite_of_unregister(void) { }
 638 #endif /* CONFIG_OF */
 639
 640 /* ---------------------------------------------------------------------
 641  * Module setup/teardown
 642  */
 643
 644 int __init ulite_init(void)
 645 {
 646         int ret;
 647
 648         pr_debug("uartlite: calling uart_register_driver()\n");
 649         ret = uart_register_driver(&ulite_uart_driver);
 650         if (ret)
 651                 goto err_uart;
 652
 653         ret = ulite_of_register();
 654         if (ret)
 655                 goto err_of;
 656
 657         pr_debug("uartlite: calling platform_driver_register()\n");
 658         ret = platform_driver_register(&ulite_platform_driver);
 659         if (ret)
 660                 goto err_plat;
 661
 662         return 0;
 663
 664 err_plat:
 665         ulite_of_unregister();
 666 err_of:
 667         uart_unregister_driver(&ulite_uart_driver);
 668 err_uart:
 669         printk(KERN_ERR "registering uartlite driver failed: err=%i", ret);
 670         return ret;
 671 }
 672
 673 void __exit ulite_exit(void)
 674 {
 675         platform_driver_unregister(&ulite_platform_driver);
 676         ulite_of_unregister();
 677         uart_unregister_driver(&ulite_uart_driver);
 678 }
 679
 680 module_init(ulite_init);
 681 module_exit(ulite_exit);
 682
 683 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 684 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
 685 MODULE_LICENSE("GPL");