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 <asm/io.h>
  21 #if defined(CONFIG_OF)
  22 #include <linux/of_device.h>
  23 #include <linux/of_platform.h>
  24 #endif
  25
  26 #define ULITE_NAME              "ttyUL"
  27 #define ULITE_MAJOR             204
  28 #define ULITE_MINOR             187
  29 #define ULITE_NR_UARTS          4
  30
  31 /* ---------------------------------------------------------------------
  32  * Register definitions
  33  *
  34  * For register details see datasheet:
  35  * http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
  36  */
  37
  38 #define ULITE_RX                0x00
  39 #define ULITE_TX                0x04
  40 #define ULITE_STATUS            0x08
  41 #define ULITE_CONTROL           0x0c
  42
  43 #define ULITE_REGION            16
  44
  45 #define ULITE_STATUS_RXVALID    0x01
  46 #define ULITE_STATUS_RXFULL     0x02
  47 #define ULITE_STATUS_TXEMPTY    0x04
  48 #define ULITE_STATUS_TXFULL     0x08
  49 #define ULITE_STATUS_IE         0x10
  50 #define ULITE_STATUS_OVERRUN    0x20
  51 #define ULITE_STATUS_FRAME      0x40
  52 #define ULITE_STATUS_PARITY     0x80
  53
  54 #define ULITE_CONTROL_RST_TX    0x01
  55 #define ULITE_CONTROL_RST_RX    0x02
  56 #define ULITE_CONTROL_IE        0x10
  57
  58
  59 static struct uart_port ulite_ports[ULITE_NR_UARTS];
  60
  61 /* ---------------------------------------------------------------------
  62  * Core UART driver operations
  63  */
  64
  65 static int ulite_receive(struct uart_port *port, int stat)
  66 {
  67         struct tty_struct *tty = port->info->tty;
  68         unsigned char ch = 0;
  69         char flag = TTY_NORMAL;
  70
  71         if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  72                      | ULITE_STATUS_FRAME)) == 0)
  73                 return 0;
  74
  75         /* stats */
  76         if (stat & ULITE_STATUS_RXVALID) {
  77                 port->icount.rx++;
  78                 ch = readb(port->membase + ULITE_RX);
  79
  80                 if (stat & ULITE_STATUS_PARITY)
  81                         port->icount.parity++;
  82         }
  83
  84         if (stat & ULITE_STATUS_OVERRUN)
  85                 port->icount.overrun++;
  86
  87         if (stat & ULITE_STATUS_FRAME)
  88                 port->icount.frame++;
  89
  90
  91         /* drop byte with parity error if IGNPAR specificed */
  92         if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
  93                 stat &= ~ULITE_STATUS_RXVALID;
  94
  95         stat &= port->read_status_mask;
  96
  97         if (stat & ULITE_STATUS_PARITY)
  98                 flag = TTY_PARITY;
  99
 100
 101         stat &= ~port->ignore_status_mask;
 102
 103         if (stat & ULITE_STATUS_RXVALID)
 104                 tty_insert_flip_char(tty, ch, flag);
 105
 106         if (stat & ULITE_STATUS_FRAME)
 107                 tty_insert_flip_char(tty, 0, TTY_FRAME);
 108
 109         if (stat & ULITE_STATUS_OVERRUN)
 110                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 111
 112         return 1;
 113 }
 114
 115 static int ulite_transmit(struct uart_port *port, int stat)
 116 {
 117         struct circ_buf *xmit  = &port->info->xmit;
 118
 119         if (stat & ULITE_STATUS_TXFULL)
 120                 return 0;
 121
 122         if (port->x_char) {
 123                 writeb(port->x_char, port->membase + ULITE_TX);
 124                 port->x_char = 0;
 125                 port->icount.tx++;
 126                 return 1;
 127         }
 128
 129         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 130                 return 0;
 131
 132         writeb(xmit->buf[xmit->tail], port->membase + ULITE_TX);
 133         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 134         port->icount.tx++;
 135
 136         /* wake up */
 137         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 138                 uart_write_wakeup(port);
 139
 140         return 1;
 141 }
 142
 143 static irqreturn_t ulite_isr(int irq, void *dev_id)
 144 {
 145         struct uart_port *port = dev_id;
 146         int busy;
 147
 148         do {
 149                 int stat = readb(port->membase + ULITE_STATUS);
 150                 busy  = ulite_receive(port, stat);
 151                 busy |= ulite_transmit(port, stat);
 152         } while (busy);
 153
 154         tty_flip_buffer_push(port->info->tty);
 155
 156         return IRQ_HANDLED;
 157 }
 158
 159 static unsigned int ulite_tx_empty(struct uart_port *port)
 160 {
 161         unsigned long flags;
 162         unsigned int ret;
 163
 164         spin_lock_irqsave(&port->lock, flags);
 165         ret = readb(port->membase + ULITE_STATUS);
 166         spin_unlock_irqrestore(&port->lock, flags);
 167
 168         return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
 169 }
 170
 171 static unsigned int ulite_get_mctrl(struct uart_port *port)
 172 {
 173         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 174 }
 175
 176 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
 177 {
 178         /* N/A */
 179 }
 180
 181 static void ulite_stop_tx(struct uart_port *port)
 182 {
 183         /* N/A */
 184 }
 185
 186 static void ulite_start_tx(struct uart_port *port)
 187 {
 188         ulite_transmit(port, readb(port->membase + ULITE_STATUS));
 189 }
 190
 191 static void ulite_stop_rx(struct uart_port *port)
 192 {
 193         /* don't forward any more data (like !CREAD) */
 194         port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 195                 | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 196 }
 197
 198 static void ulite_enable_ms(struct uart_port *port)
 199 {
 200         /* N/A */
 201 }
 202
 203 static void ulite_break_ctl(struct uart_port *port, int ctl)
 204 {
 205         /* N/A */
 206 }
 207
 208 static int ulite_startup(struct uart_port *port)
 209 {
 210         int ret;
 211
 212         ret = request_irq(port->irq, ulite_isr,
 213                           IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "uartlite", port);
 214         if (ret)
 215                 return ret;
 216
 217         writeb(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
 218                port->membase + ULITE_CONTROL);
 219         writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 220
 221         return 0;
 222 }
 223
 224 static void ulite_shutdown(struct uart_port *port)
 225 {
 226         writeb(0, port->membase + ULITE_CONTROL);
 227         readb(port->membase + ULITE_CONTROL); /* dummy */
 228         free_irq(port->irq, port);
 229 }
 230
 231 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
 232                               struct ktermios *old)
 233 {
 234         unsigned long flags;
 235         unsigned int baud;
 236
 237         spin_lock_irqsave(&port->lock, flags);
 238
 239         port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 240                 | ULITE_STATUS_TXFULL;
 241
 242         if (termios->c_iflag & INPCK)
 243                 port->read_status_mask |=
 244                         ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
 245
 246         port->ignore_status_mask = 0;
 247         if (termios->c_iflag & IGNPAR)
 248                 port->ignore_status_mask |= ULITE_STATUS_PARITY
 249                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 250
 251         /* ignore all characters if CREAD is not set */
 252         if ((termios->c_cflag & CREAD) == 0)
 253                 port->ignore_status_mask |=
 254                         ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 255                         | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 256
 257         /* update timeout */
 258         baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 259         uart_update_timeout(port, termios->c_cflag, baud);
 260
 261         spin_unlock_irqrestore(&port->lock, flags);
 262 }
 263
 264 static const char *ulite_type(struct uart_port *port)
 265 {
 266         return port->type == PORT_UARTLITE ? "uartlite" : NULL;
 267 }
 268
 269 static void ulite_release_port(struct uart_port *port)
 270 {
 271         release_mem_region(port->mapbase, ULITE_REGION);
 272         iounmap(port->membase);
 273         port->membase = NULL;
 274 }
 275
 276 static int ulite_request_port(struct uart_port *port)
 277 {
 278         if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
 279                 dev_err(port->dev, "Memory region busy\n");
 280                 return -EBUSY;
 281         }
 282
 283         port->membase = ioremap(port->mapbase, ULITE_REGION);
 284         if (!port->membase) {
 285                 dev_err(port->dev, "Unable to map registers\n");
 286                 release_mem_region(port->mapbase, ULITE_REGION);
 287                 return -EBUSY;
 288         }
 289
 290         return 0;
 291 }
 292
 293 static void ulite_config_port(struct uart_port *port, int flags)
 294 {
 295         if (!ulite_request_port(port))
 296                 port->type = PORT_UARTLITE;
 297 }
 298
 299 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
 300 {
 301         /* we don't want the core code to modify any port params */
 302         return -EINVAL;
 303 }
 304
 305 static struct uart_ops ulite_ops = {
 306         .tx_empty       = ulite_tx_empty,
 307         .set_mctrl      = ulite_set_mctrl,
 308         .get_mctrl      = ulite_get_mctrl,
 309         .stop_tx        = ulite_stop_tx,
 310         .start_tx       = ulite_start_tx,
 311         .stop_rx        = ulite_stop_rx,
 312         .enable_ms      = ulite_enable_ms,
 313         .break_ctl      = ulite_break_ctl,
 314         .startup        = ulite_startup,
 315         .shutdown       = ulite_shutdown,
 316         .set_termios    = ulite_set_termios,
 317         .type           = ulite_type,
 318         .release_port   = ulite_release_port,
 319         .request_port   = ulite_request_port,
 320         .config_port    = ulite_config_port,
 321         .verify_port    = ulite_verify_port
 322 };
 323
 324 /* ---------------------------------------------------------------------
 325  * Console driver operations
 326  */
 327
 328 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 329 static void ulite_console_wait_tx(struct uart_port *port)
 330 {
 331         int i;
 332         u8 val;
 333
 334         /* Spin waiting for TX fifo to have space available */
 335         for (i = 0; i < 100000; i++) {
 336                 val = readb(port->membase + ULITE_STATUS);
 337                 if ((val & ULITE_STATUS_TXFULL) == 0)
 338                         break;
 339                 cpu_relax();
 340         }
 341 }
 342
 343 static void ulite_console_putchar(struct uart_port *port, int ch)
 344 {
 345         ulite_console_wait_tx(port);
 346         writeb(ch, port->membase + ULITE_TX);
 347 }
 348
 349 static void ulite_console_write(struct console *co, const char *s,
 350                                 unsigned int count)
 351 {
 352         struct uart_port *port = &ulite_ports[co->index];
 353         unsigned long flags;
 354         unsigned int ier;
 355         int locked = 1;
 356
 357         if (oops_in_progress) {
 358                 locked = spin_trylock_irqsave(&port->lock, flags);
 359         } else
 360                 spin_lock_irqsave(&port->lock, flags);
 361
 362         /* save and disable interrupt */
 363         ier = readb(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
 364         writeb(0, port->membase + ULITE_CONTROL);
 365
 366         uart_console_write(port, s, count, ulite_console_putchar);
 367
 368         ulite_console_wait_tx(port);
 369
 370         /* restore interrupt state */
 371         if (ier)
 372                 writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
 373
 374         if (locked)
 375                 spin_unlock_irqrestore(&port->lock, flags);
 376 }
 377
 378 #if defined(CONFIG_OF)
 379 static inline void __init ulite_console_of_find_device(int id)
 380 {
 381         struct device_node *np;
 382         struct resource res;
 383         const unsigned int *of_id;
 384         int rc;
 385
 386         for_each_compatible_node(np, NULL, "xilinx,uartlite") {
 387                 of_id = of_get_property(np, "port-number", NULL);
 388                 if ((!of_id) || (*of_id != id))
 389                         continue;
 390
 391                 rc = of_address_to_resource(np, 0, &res);
 392                 if (rc)
 393                         continue;
 394
 395                 ulite_ports[id].mapbase = res.start;
 396                 of_node_put(np);
 397                 return;
 398         }
 399 }
 400 #else /* CONFIG_OF */
 401 static inline void __init ulite_console_of_find_device(int id) { /* do nothing */ }
 402 #endif /* CONFIG_OF */
 403
 404 static int __init ulite_console_setup(struct console *co, char *options)
 405 {
 406         struct uart_port *port;
 407         int baud = 9600;
 408         int bits = 8;
 409         int parity = 'n';
 410         int flow = 'n';
 411
 412         if (co->index < 0 || co->index >= ULITE_NR_UARTS)
 413                 return -EINVAL;
 414
 415         port = &ulite_ports[co->index];
 416
 417         /* Check if it is an OF device */
 418         if (!port->mapbase)
 419                 ulite_console_of_find_device(co->index);
 420
 421         /* Do we have a device now? */
 422         if (!port->mapbase) {
 423                 pr_debug("console on ttyUL%i not present\n", co->index);
 424                 return -ENODEV;
 425         }
 426
 427         /* not initialized yet? */
 428         if (!port->membase) {
 429                 if (ulite_request_port(port))
 430                         return -ENODEV;
 431         }
 432
 433         if (options)
 434                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 435
 436         return uart_set_options(port, co, baud, parity, bits, flow);
 437 }
 438
 439 static struct uart_driver ulite_uart_driver;
 440
 441 static struct console ulite_console = {
 442         .name   = ULITE_NAME,
 443         .write  = ulite_console_write,
 444         .device = uart_console_device,
 445         .setup  = ulite_console_setup,
 446         .flags  = CON_PRINTBUFFER,
 447         .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
 448         .data   = &ulite_uart_driver,
 449 };
 450
 451 static int __init ulite_console_init(void)
 452 {
 453         register_console(&ulite_console);
 454         return 0;
 455 }
 456
 457 console_initcall(ulite_console_init);
 458
 459 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
 460
 461 static struct uart_driver ulite_uart_driver = {
 462         .owner          = THIS_MODULE,
 463         .driver_name    = "uartlite",
 464         .dev_name       = ULITE_NAME,
 465         .major          = ULITE_MAJOR,
 466         .minor          = ULITE_MINOR,
 467         .nr             = ULITE_NR_UARTS,
 468 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 469         .cons           = &ulite_console,
 470 #endif
 471 };
 472
 473 /* ---------------------------------------------------------------------
 474  * Port assignment functions (mapping devices to uart_port structures)
 475  */
 476
 477 /** ulite_assign: register a uartlite device with the driver
 478  *
 479  * @dev: pointer to device structure
 480  * @id: requested id number.  Pass -1 for automatic port assignment
 481  * @base: base address of uartlite registers
 482  * @irq: irq number for uartlite
 483  *
 484  * Returns: 0 on success, <0 otherwise
 485  */
 486 static int __devinit ulite_assign(struct device *dev, int id, u32 base, int irq)
 487 {
 488         struct uart_port *port;
 489         int rc;
 490
 491         /* if id = -1; then scan for a free id and use that */
 492         if (id < 0) {
 493                 for (id = 0; id < ULITE_NR_UARTS; id++)
 494                         if (ulite_ports[id].mapbase == 0)
 495                                 break;
 496         }
 497         if (id < 0 || id >= ULITE_NR_UARTS) {
 498                 dev_err(dev, "%s%i too large\n", ULITE_NAME, id);
 499                 return -EINVAL;
 500         }
 501
 502         if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {
 503                 dev_err(dev, "cannot assign to %s%i; it is already in use\n",
 504                         ULITE_NAME, id);
 505                 return -EBUSY;
 506         }
 507
 508         port = &ulite_ports[id];
 509
 510         spin_lock_init(&port->lock);
 511         port->fifosize = 16;
 512         port->regshift = 2;
 513         port->iotype = UPIO_MEM;
 514         port->iobase = 1; /* mark port in use */
 515         port->mapbase = base;
 516         port->membase = NULL;
 517         port->ops = &ulite_ops;
 518         port->irq = irq;
 519         port->flags = UPF_BOOT_AUTOCONF;
 520         port->dev = dev;
 521         port->type = PORT_UNKNOWN;
 522         port->line = id;
 523
 524         dev_set_drvdata(dev, port);
 525
 526         /* Register the port */
 527         rc = uart_add_one_port(&ulite_uart_driver, port);
 528         if (rc) {
 529                 dev_err(dev, "uart_add_one_port() failed; err=%i\n", rc);
 530                 port->mapbase = 0;
 531                 dev_set_drvdata(dev, NULL);
 532                 return rc;
 533         }
 534
 535         return 0;
 536 }
 537
 538 /** ulite_release: register a uartlite device with the driver
 539  *
 540  * @dev: pointer to device structure
 541  */
 542 static int __devexit ulite_release(struct device *dev)
 543 {
 544         struct uart_port *port = dev_get_drvdata(dev);
 545         int rc = 0;
 546
 547         if (port) {
 548                 rc = uart_remove_one_port(&ulite_uart_driver, port);
 549                 dev_set_drvdata(dev, NULL);
 550                 port->mapbase = 0;
 551         }
 552
 553         return rc;
 554 }
 555
 556 /* ---------------------------------------------------------------------
 557  * Platform bus binding
 558  */
 559
 560 static int __devinit ulite_probe(struct platform_device *pdev)
 561 {
 562         struct resource *res, *res2;
 563
 564         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 565         if (!res)
 566                 return -ENODEV;
 567
 568         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 569         if (!res2)
 570                 return -ENODEV;
 571
 572         return ulite_assign(&pdev->dev, pdev->id, res->start, res2->start);
 573 }
 574
 575 static int __devexit ulite_remove(struct platform_device *pdev)
 576 {
 577         return ulite_release(&pdev->dev);
 578 }
 579
 580 static struct platform_driver ulite_platform_driver = {
 581         .probe  = ulite_probe,
 582         .remove = __devexit_p(ulite_remove),
 583         .driver = {
 584                    .owner = THIS_MODULE,
 585                    .name  = "uartlite",
 586                    },
 587 };
 588
 589 /* ---------------------------------------------------------------------
 590  * OF bus bindings
 591  */
 592 #if defined(CONFIG_OF)
 593 static int __devinit
 594 ulite_of_probe(struct of_device *op, const struct of_device_id *match)
 595 {
 596         struct resource res;
 597         const unsigned int *id;
 598         int irq, rc;
 599
 600         dev_dbg(&op->dev, "%s(%p, %p)\n", __FUNCTION__, op, match);
 601
 602         rc = of_address_to_resource(op->node, 0, &res);
 603         if (rc) {
 604                 dev_err(&op->dev, "invalid address\n");
 605                 return rc;
 606         }
 607
 608         irq = irq_of_parse_and_map(op->node, 0);
 609
 610         id = of_get_property(op->node, "port-number", NULL);
 611
 612         return ulite_assign(&op->dev, id ? *id : -1, res.start+3, irq);
 613 }
 614
 615 static int __devexit ulite_of_remove(struct of_device *op)
 616 {
 617         return ulite_release(&op->dev);
 618 }
 619
 620 /* Match table for of_platform binding */
 621 static struct of_device_id __devinit ulite_of_match[] = {
 622         { .type = "serial", .compatible = "xilinx,uartlite", },
 623         {},
 624 };
 625 MODULE_DEVICE_TABLE(of, ulite_of_match);
 626
 627 static struct of_platform_driver ulite_of_driver = {
 628         .owner = THIS_MODULE,
 629         .name = "uartlite",
 630         .match_table = ulite_of_match,
 631         .probe = ulite_of_probe,
 632         .remove = __devexit_p(ulite_of_remove),
 633         .driver = {
 634                 .name = "uartlite",
 635         },
 636 };
 637
 638 /* Registration helpers to keep the number of #ifdefs to a minimum */
 639 static inline int __init ulite_of_register(void)
 640 {
 641         pr_debug("uartlite: calling of_register_platform_driver()\n");
 642         return of_register_platform_driver(&ulite_of_driver);
 643 }
 644
 645 static inline void __exit ulite_of_unregister(void)
 646 {
 647         of_unregister_platform_driver(&ulite_of_driver);
 648 }
 649 #else /* CONFIG_OF */
 650 /* CONFIG_OF not enabled; do nothing helpers */
 651 static inline int __init ulite_of_register(void) { return 0; }
 652 static inline void __exit ulite_of_unregister(void) { }
 653 #endif /* CONFIG_OF */
 654
 655 /* ---------------------------------------------------------------------
 656  * Module setup/teardown
 657  */
 658
 659 int __init ulite_init(void)
 660 {
 661         int ret;
 662
 663         pr_debug("uartlite: calling uart_register_driver()\n");
 664         ret = uart_register_driver(&ulite_uart_driver);
 665         if (ret)
 666                 goto err_uart;
 667
 668         ret = ulite_of_register();
 669         if (ret)
 670                 goto err_of;
 671
 672         pr_debug("uartlite: calling platform_driver_register()\n");
 673         ret = platform_driver_register(&ulite_platform_driver);
 674         if (ret)
 675                 goto err_plat;
 676
 677         return 0;
 678
 679 err_plat:
 680         ulite_of_unregister();
 681 err_of:
 682         uart_unregister_driver(&ulite_uart_driver);
 683 err_uart:
 684         printk(KERN_ERR "registering uartlite driver failed: err=%i", ret);
 685         return ret;
 686 }
 687
 688 void __exit ulite_exit(void)
 689 {
 690         platform_driver_unregister(&ulite_platform_driver);
 691         ulite_of_unregister();
 692         uart_unregister_driver(&ulite_uart_driver);
 693 }
 694
 695 module_init(ulite_init);
 696 module_exit(ulite_exit);
 697
 698 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 699 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
 700 MODULE_LICENSE("GPL");