drivers/tty/serial/apbuart.c

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