drivers/tty/serial/arc_uart.c

   1 /*
   2  * ARC On-Chip(fpga) UART Driver
   3  *
   4  * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com)
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * vineetg: July 10th 2012
  11  *  -Decoupled the driver from arch/arc
  12  *    +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
  13  *    +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
  14  *
  15  * Vineetg: Aug 21st 2010
  16  *  -Is uart_tx_stopped() not done in tty write path as it has already been
  17  *   taken care of, in serial core
  18  *
  19  * Vineetg: Aug 18th 2010
  20  *  -New Serial Core based ARC UART driver
  21  *  -Derived largely from blackfin driver albiet with some major tweaks
  22  *
  23  * TODO:
  24  *  -check if sysreq works
  25  */
  26
  27 #if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
  28 #define SUPPORT_SYSRQ
  29 #endif
  30
  31 #include <linux/module.h>
  32 #include <linux/serial.h>
  33 #include <linux/console.h>
  34 #include <linux/sysrq.h>
  35 #include <linux/platform_device.h>
  36 #include <linux/tty.h>
  37 #include <linux/tty_flip.h>
  38 #include <linux/serial_core.h>
  39 #include <linux/io.h>
  40
  41 /*************************************
  42  * ARC UART Hardware Specs
  43  ************************************/
  44 #define ARC_UART_TX_FIFO_SIZE  1
  45
  46 /*
  47  * UART Register set (this is not a Standards Compliant IP)
  48  * Also each reg is Word aligned, but only 8 bits wide
  49  */
  50 #define R_ID0   0
  51 #define R_ID1   4
  52 #define R_ID2   8
  53 #define R_ID3   12
  54 #define R_DATA  16
  55 #define R_STS   20
  56 #define R_BAUDL 24
  57 #define R_BAUDH 28
  58
  59 /* Bits for UART Status Reg (R/W) */
  60 #define RXIENB  0x04    /* Receive Interrupt Enable */
  61 #define TXIENB  0x40    /* Transmit Interrupt Enable */
  62
  63 #define RXEMPTY 0x20    /* Receive FIFO Empty: No char receivede */
  64 #define TXEMPTY 0x80    /* Transmit FIFO Empty, thus char can be written into */
  65
  66 #define RXFULL  0x08    /* Receive FIFO full */
  67 #define RXFULL1 0x10    /* Receive FIFO has space for 1 char (tot space=4) */
  68
  69 #define RXFERR  0x01    /* Frame Error: Stop Bit not detected */
  70 #define RXOERR  0x02    /* OverFlow Err: Char recv but RXFULL still set */
  71
  72 /* Uart bit fiddling helpers: lowest level */
  73 #define RBASE(uart, reg)      (uart->port.membase + reg)
  74 #define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
  75 #define UART_REG_GET(u, r)    readb(RBASE(u, r))
  76
  77 #define UART_REG_OR(u, r, v)  UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
  78 #define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
  79
  80 /* Uart bit fiddling helpers: API level */
  81 #define UART_SET_DATA(uart, val)   UART_REG_SET(uart, R_DATA, val)
  82 #define UART_GET_DATA(uart)        UART_REG_GET(uart, R_DATA)
  83
  84 #define UART_SET_BAUDH(uart, val)  UART_REG_SET(uart, R_BAUDH, val)
  85 #define UART_SET_BAUDL(uart, val)  UART_REG_SET(uart, R_BAUDL, val)
  86
  87 #define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
  88 #define UART_GET_STATUS(uart)      UART_REG_GET(uart, R_STS)
  89
  90 #define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
  91 #define UART_RX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, RXIENB)
  92 #define UART_TX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, TXIENB)
  93
  94 #define UART_ALL_IRQ_ENABLE(uart)  UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
  95 #define UART_RX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, RXIENB)
  96 #define UART_TX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, TXIENB)
  97
  98 #define ARC_SERIAL_DEV_NAME     "ttyARC"
  99
 100 struct arc_uart_port {
 101         struct uart_port port;
 102         unsigned long baud;
 103         int is_emulated;        /* H/w vs. Instruction Set Simulator */
 104 };
 105
 106 #define to_arc_port(uport)  container_of(uport, struct arc_uart_port, port)
 107
 108 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
 109
 110 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 111 static struct console arc_console;
 112 #endif
 113
 114 #define DRIVER_NAME     "arc-uart"
 115
 116 static struct uart_driver arc_uart_driver = {
 117         .owner          = THIS_MODULE,
 118         .driver_name    = DRIVER_NAME,
 119         .dev_name       = ARC_SERIAL_DEV_NAME,
 120         .major          = 0,
 121         .minor          = 0,
 122         .nr             = CONFIG_SERIAL_ARC_NR_PORTS,
 123 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 124         .cons           = &arc_console,
 125 #endif
 126 };
 127
 128 static void arc_serial_stop_rx(struct uart_port *port)
 129 {
 130         struct arc_uart_port *uart = to_arc_port(port);
 131
 132         UART_RX_IRQ_DISABLE(uart);
 133 }
 134
 135 static void arc_serial_stop_tx(struct uart_port *port)
 136 {
 137         struct arc_uart_port *uart = to_arc_port(port);
 138
 139         while (!(UART_GET_STATUS(uart) & TXEMPTY))
 140                 cpu_relax();
 141
 142         UART_TX_IRQ_DISABLE(uart);
 143 }
 144
 145 /*
 146  * Return TIOCSER_TEMT when transmitter is not busy.
 147  */
 148 static unsigned int arc_serial_tx_empty(struct uart_port *port)
 149 {
 150         struct arc_uart_port *uart = to_arc_port(port);
 151         unsigned int stat;
 152
 153         stat = UART_GET_STATUS(uart);
 154         if (stat & TXEMPTY)
 155                 return TIOCSER_TEMT;
 156
 157         return 0;
 158 }
 159
 160 /*
 161  * Driver internal routine, used by both tty(serial core) as well as tx-isr
 162  *  -Called under spinlock in either cases
 163  *  -also tty->stopped / tty->hw_stopped has already been checked
 164  *     = by uart_start( ) before calling us
 165  *     = tx_ist checks that too before calling
 166  */
 167 static void arc_serial_tx_chars(struct arc_uart_port *uart)
 168 {
 169         struct circ_buf *xmit = &uart->port.state->xmit;
 170         int sent = 0;
 171         unsigned char ch;
 172
 173         if (unlikely(uart->port.x_char)) {
 174                 UART_SET_DATA(uart, uart->port.x_char);
 175                 uart->port.icount.tx++;
 176                 uart->port.x_char = 0;
 177                 sent = 1;
 178         } else if (xmit->tail != xmit->head) {  /* TODO: uart_circ_empty */
 179                 ch = xmit->buf[xmit->tail];
 180                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 181                 uart->port.icount.tx++;
 182                 while (!(UART_GET_STATUS(uart) & TXEMPTY))
 183                         cpu_relax();
 184                 UART_SET_DATA(uart, ch);
 185                 sent = 1;
 186         }
 187
 188         /*
 189          * If num chars in xmit buffer are too few, ask tty layer for more.
 190          * By Hard ISR to schedule processing in software interrupt part
 191          */
 192         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 193                 uart_write_wakeup(&uart->port);
 194
 195         if (sent)
 196                 UART_TX_IRQ_ENABLE(uart);
 197 }
 198
 199 /*
 200  * port is locked and interrupts are disabled
 201  * uart_start( ) calls us under the port spinlock irqsave
 202  */
 203 static void arc_serial_start_tx(struct uart_port *port)
 204 {
 205         struct arc_uart_port *uart = to_arc_port(port);
 206
 207         arc_serial_tx_chars(uart);
 208 }
 209
 210 static void arc_serial_rx_chars(struct arc_uart_port *uart)
 211 {
 212         struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
 213         unsigned int status, ch, flg = 0;
 214
 215         if (!tty)
 216                 return;
 217
 218         /*
 219          * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
 220          * is very subtle. Here's how ...
 221          * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
 222          * driver reads the DATA Reg and keeps doing that in a loop, until
 223          * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
 224          * before RX-EMPTY=0, implies some sort of buffering going on in the
 225          * controller, which is indeed the Rx-FIFO.
 226          */
 227         while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
 228
 229                 ch = UART_GET_DATA(uart);
 230                 uart->port.icount.rx++;
 231
 232                 if (unlikely(status & (RXOERR | RXFERR))) {
 233                         if (status & RXOERR) {
 234                                 uart->port.icount.overrun++;
 235                                 flg = TTY_OVERRUN;
 236                                 UART_CLR_STATUS(uart, RXOERR);
 237                         }
 238
 239                         if (status & RXFERR) {
 240                                 uart->port.icount.frame++;
 241                                 flg = TTY_FRAME;
 242                                 UART_CLR_STATUS(uart, RXFERR);
 243                         }
 244                 } else
 245                         flg = TTY_NORMAL;
 246
 247                 if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
 248                         goto done;
 249
 250                 uart_insert_char(&uart->port, status, RXOERR, ch, flg);
 251
 252 done:
 253                 tty_flip_buffer_push(tty);
 254         }
 255
 256         tty_kref_put(tty);
 257 }
 258
 259 /*
 260  * A note on the Interrupt handling state machine of this driver
 261  *
 262  * kernel printk writes funnel thru the console driver framework and in order
 263  * to keep things simple as well as efficient, it writes to UART in polled
 264  * mode, in one shot, and exits.
 265  *
 266  * OTOH, Userland output (via tty layer), uses interrupt based writes as there
 267  * can be undeterministic delay between char writes.
 268  *
 269  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
 270  * disabled.
 271  *
 272  * When tty has some data to send out, serial core calls driver's start_tx
 273  * which
 274  *   -checks-if-tty-buffer-has-char-to-send
 275  *   -writes-data-to-uart
 276  *   -enable-tx-intr
 277  *
 278  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
 279  * The first thing Tx ISR does is disable further Tx interrupts (as this could
 280  * be the last char to send, before settling down into the quiet polled mode).
 281  * It then calls the exact routine used by tty layer write to send out any
 282  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
 283  * of no data, it remains disabled.
 284  * This is how the transmit state machine is dynamically switched on/off
 285  */
 286
 287 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
 288 {
 289         struct arc_uart_port *uart = dev_id;
 290         unsigned int status;
 291
 292         status = UART_GET_STATUS(uart);
 293
 294         /*
 295          * Single IRQ for both Rx (data available) Tx (room available) Interrupt
 296          * notifications from the UART Controller.
 297          * To demultiplex between the two, we check the relevant bits
 298          */
 299         if ((status & RXIENB) && !(status & RXEMPTY)) {
 300
 301                 /* already in ISR, no need of xx_irqsave */
 302                 spin_lock(&uart->port.lock);
 303                 arc_serial_rx_chars(uart);
 304                 spin_unlock(&uart->port.lock);
 305         }
 306
 307         if ((status & TXIENB) && (status & TXEMPTY)) {
 308
 309                 /* Unconditionally disable further Tx-Interrupts.
 310                  * will be enabled by tx_chars() if needed.
 311                  */
 312                 UART_TX_IRQ_DISABLE(uart);
 313
 314                 spin_lock(&uart->port.lock);
 315
 316                 if (!uart_tx_stopped(&uart->port))
 317                         arc_serial_tx_chars(uart);
 318
 319                 spin_unlock(&uart->port.lock);
 320         }
 321
 322         return IRQ_HANDLED;
 323 }
 324
 325 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
 326 {
 327         /*
 328          * Pretend we have a Modem status reg and following bits are
 329          *  always set, to satify the serial core state machine
 330          *  (DSR) Data Set Ready
 331          *  (CTS) Clear To Send
 332          *  (CAR) Carrier Detect
 333          */
 334         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 335 }
 336
 337 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 338 {
 339         /* MCR not present */
 340 }
 341
 342 /* Enable Modem Status Interrupts */
 343
 344 static void arc_serial_enable_ms(struct uart_port *port)
 345 {
 346         /* MSR not present */
 347 }
 348
 349 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
 350 {
 351         /* ARC UART doesn't support sending Break signal */
 352 }
 353
 354 static int arc_serial_startup(struct uart_port *port)
 355 {
 356         struct arc_uart_port *uart = to_arc_port(port);
 357
 358         /* Before we hook up the ISR, Disable all UART Interrupts */
 359         UART_ALL_IRQ_DISABLE(uart);
 360
 361         if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
 362                         uart)) {
 363                 dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n");
 364                 return -EBUSY;
 365         }
 366
 367         UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
 368
 369         return 0;
 370 }
 371
 372 /* This is not really needed */
 373 static void arc_serial_shutdown(struct uart_port *port)
 374 {
 375         struct arc_uart_port *uart = to_arc_port(port);
 376         free_irq(uart->port.irq, uart);
 377 }
 378
 379 static void
 380 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
 381                        struct ktermios *old)
 382 {
 383         struct arc_uart_port *uart = to_arc_port(port);
 384         unsigned int baud, uartl, uarth, hw_val;
 385         unsigned long flags;
 386
 387         /*
 388          * Use the generic handler so that any specially encoded baud rates
 389          * such as SPD_xx flags or "%B0" can be handled
 390          * Max Baud I suppose will not be more than current 115K * 4
 391          * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
 392          * spread over two 8-bit registers
 393          */
 394         baud = uart_get_baud_rate(port, new, old, 0, 460800);
 395
 396         hw_val = port->uartclk / (uart->baud * 4) - 1;
 397         uartl = hw_val & 0xFF;
 398         uarth = (hw_val >> 8) & 0xFF;
 399
 400         /*
 401          * UART ISS(Instruction Set simulator) emulation has a subtle bug:
 402          * A existing value of Baudh = 0 is used as a indication to startup
 403          * it's internal state machine.
 404          * Thus if baudh is set to 0, 2 times, it chokes.
 405          * This happens with BAUD=115200 and the formaula above
 406          * Until that is fixed, when running on ISS, we will set baudh to !0
 407          */
 408         if (uart->is_emulated)
 409                 uarth = 1;
 410
 411         spin_lock_irqsave(&port->lock, flags);
 412
 413         UART_ALL_IRQ_DISABLE(uart);
 414
 415         UART_SET_BAUDL(uart, uartl);
 416         UART_SET_BAUDH(uart, uarth);
 417
 418         UART_RX_IRQ_ENABLE(uart);
 419
 420         /*
 421          * UART doesn't support Parity/Hardware Flow Control;
 422          * Only supports 8N1 character size
 423          */
 424         new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
 425         new->c_cflag |= CS8;
 426
 427         if (old)
 428                 tty_termios_copy_hw(new, old);
 429
 430         /* Don't rewrite B0 */
 431         if (tty_termios_baud_rate(new))
 432                 tty_termios_encode_baud_rate(new, baud, baud);
 433
 434         uart_update_timeout(port, new->c_cflag, baud);
 435
 436         spin_unlock_irqrestore(&port->lock, flags);
 437 }
 438
 439 static const char *arc_serial_type(struct uart_port *port)
 440 {
 441         struct arc_uart_port *uart = to_arc_port(port);
 442
 443         return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
 444 }
 445
 446 static void arc_serial_release_port(struct uart_port *port)
 447 {
 448 }
 449
 450 static int arc_serial_request_port(struct uart_port *port)
 451 {
 452         return 0;
 453 }
 454
 455 /*
 456  * Verify the new serial_struct (for TIOCSSERIAL).
 457  */
 458 static int
 459 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 460 {
 461         if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
 462                 return -EINVAL;
 463
 464         return 0;
 465 }
 466
 467 /*
 468  * Configure/autoconfigure the port.
 469  */
 470 static void arc_serial_config_port(struct uart_port *port, int flags)
 471 {
 472         struct arc_uart_port *uart = to_arc_port(port);
 473
 474         if (flags & UART_CONFIG_TYPE)
 475                 uart->port.type = PORT_ARC;
 476 }
 477
 478 #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
 479
 480 static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
 481 {
 482         struct arc_uart_port *uart = to_arc_port(port);
 483
 484         while (!(UART_GET_STATUS(uart) & TXEMPTY))
 485                 cpu_relax();
 486
 487         UART_SET_DATA(uart, chr);
 488 }
 489 #endif
 490
 491 #ifdef CONFIG_CONSOLE_POLL
 492 static int arc_serial_poll_getchar(struct uart_port *port)
 493 {
 494         struct arc_uart_port *uart = to_arc_port(port);
 495         unsigned char chr;
 496
 497         while (!(UART_GET_STATUS(uart) & RXEMPTY))
 498                 cpu_relax();
 499
 500         chr = UART_GET_DATA(uart);
 501         return chr;
 502 }
 503 #endif
 504
 505 static struct uart_ops arc_serial_pops = {
 506         .tx_empty       = arc_serial_tx_empty,
 507         .set_mctrl      = arc_serial_set_mctrl,
 508         .get_mctrl      = arc_serial_get_mctrl,
 509         .stop_tx        = arc_serial_stop_tx,
 510         .start_tx       = arc_serial_start_tx,
 511         .stop_rx        = arc_serial_stop_rx,
 512         .enable_ms      = arc_serial_enable_ms,
 513         .break_ctl      = arc_serial_break_ctl,
 514         .startup        = arc_serial_startup,
 515         .shutdown       = arc_serial_shutdown,
 516         .set_termios    = arc_serial_set_termios,
 517         .type           = arc_serial_type,
 518         .release_port   = arc_serial_release_port,
 519         .request_port   = arc_serial_request_port,
 520         .config_port    = arc_serial_config_port,
 521         .verify_port    = arc_serial_verify_port,
 522 #ifdef CONFIG_CONSOLE_POLL
 523         .poll_put_char = arc_serial_poll_putchar,
 524         .poll_get_char = arc_serial_poll_getchar,
 525 #endif
 526 };
 527
 528 static int
 529 arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
 530 {
 531         struct resource *res, *res2;
 532         unsigned long *plat_data;
 533
 534         if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
 535                 dev_err(&pdev->dev, "Wrong uart platform device id.\n");
 536                 return -ENOENT;
 537         }
 538
 539         plat_data = ((unsigned long *)(pdev->dev.platform_data));
 540         uart->baud = plat_data[0];
 541
 542         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 543         if (!res)
 544                 return -ENODEV;
 545
 546         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 547         if (!res2)
 548                 return -ENODEV;
 549
 550         uart->port.mapbase = res->start;
 551         uart->port.membase = ioremap_nocache(res->start, resource_size(res));
 552         if (!uart->port.membase)
 553                 /* No point of dev_err since UART itself is hosed here */
 554                 return -ENXIO;
 555
 556         uart->port.irq = res2->start;
 557         uart->port.dev = &pdev->dev;
 558         uart->port.iotype = UPIO_MEM;
 559         uart->port.flags = UPF_BOOT_AUTOCONF;
 560         uart->port.line = pdev->id;
 561         uart->port.ops = &arc_serial_pops;
 562
 563         uart->port.uartclk = plat_data[1];
 564         uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
 565
 566         /*
 567          * uart_insert_char( ) uses it in decideding whether to ignore a
 568          * char or not. Explicitly setting it here, removes the subtelty
 569          */
 570         uart->port.ignore_status_mask = 0;
 571
 572         /* Real Hardware vs. emulated to work around a bug */
 573         uart->is_emulated = !!plat_data[2];
 574
 575         return 0;
 576 }
 577
 578 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 579
 580 static int arc_serial_console_setup(struct console *co, char *options)
 581 {
 582         struct uart_port *port;
 583         int baud = 115200;
 584         int bits = 8;
 585         int parity = 'n';
 586         int flow = 'n';
 587
 588         if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
 589                 return -ENODEV;
 590
 591         /*
 592          * The uart port backing the console (e.g. ttyARC1) might not have been
 593          * init yet. If so, defer the console setup to after the port.
 594          */
 595         port = &arc_uart_ports[co->index].port;
 596         if (!port->membase)
 597                 return -ENODEV;
 598
 599         if (options)
 600                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 601
 602         /*
 603          * Serial core will call port->ops->set_termios( )
 604          * which will set the baud reg
 605          */
 606         return uart_set_options(port, co, baud, parity, bits, flow);
 607 }
 608
 609 static void arc_serial_console_putchar(struct uart_port *port, int ch)
 610 {
 611         arc_serial_poll_putchar(port, (unsigned char)ch);
 612 }
 613
 614 /*
 615  * Interrupts are disabled on entering
 616  */
 617 static void arc_serial_console_write(struct console *co, const char *s,
 618                                      unsigned int count)
 619 {
 620         struct uart_port *port = &arc_uart_ports[co->index].port;
 621         unsigned long flags;
 622
 623         spin_lock_irqsave(&port->lock, flags);
 624         uart_console_write(port, s, count, arc_serial_console_putchar);
 625         spin_unlock_irqrestore(&port->lock, flags);
 626 }
 627
 628 static struct console arc_console = {
 629         .name   = ARC_SERIAL_DEV_NAME,
 630         .write  = arc_serial_console_write,
 631         .device = uart_console_device,
 632         .setup  = arc_serial_console_setup,
 633         .flags  = CON_PRINTBUFFER,
 634         .index  = -1,
 635         .data   = &arc_uart_driver
 636 };
 637
 638 static __init void early_serial_write(struct console *con, const char *s,
 639                                         unsigned int n)
 640 {
 641         struct uart_port *port = &arc_uart_ports[con->index].port;
 642         unsigned int i;
 643
 644         for (i = 0; i < n; i++, s++) {
 645                 if (*s == '\n')
 646                         arc_serial_poll_putchar(port, '\r');
 647                 arc_serial_poll_putchar(port, *s);
 648         }
 649 }
 650
 651 static struct __initdata console arc_early_serial_console = {
 652         .name = "early_ARCuart",
 653         .write = early_serial_write,
 654         .flags = CON_PRINTBUFFER | CON_BOOT,
 655         .index = -1
 656 };
 657
 658 static int arc_serial_probe_earlyprintk(struct platform_device *pdev)
 659 {
 660         arc_early_serial_console.index = pdev->id;
 661
 662         arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
 663
 664         arc_serial_console_setup(&arc_early_serial_console, NULL);
 665
 666         register_console(&arc_early_serial_console);
 667         return 0;
 668 }
 669 #else
 670 static int arc_serial_probe_earlyprintk(struct platform_device *pdev)
 671 {
 672         return -ENODEV;
 673 }
 674 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
 675
 676 static int arc_serial_probe(struct platform_device *pdev)
 677 {
 678         struct arc_uart_port *uart;
 679         int rc;
 680
 681         if (is_early_platform_device(pdev))
 682                 return arc_serial_probe_earlyprintk(pdev);
 683
 684         uart = &arc_uart_ports[pdev->id];
 685         rc = arc_uart_init_one(pdev, uart);
 686         if (rc)
 687                 return rc;
 688
 689         return uart_add_one_port(&arc_uart_driver, &uart->port);
 690 }
 691
 692 static int __devexit arc_serial_remove(struct platform_device *pdev)
 693 {
 694         /* This will never be called */
 695         return 0;
 696 }
 697
 698 static struct platform_driver arc_platform_driver = {
 699         .probe = arc_serial_probe,
 700         .remove = arc_serial_remove,
 701         .driver = {
 702                 .name = DRIVER_NAME,
 703                 .owner = THIS_MODULE,
 704          },
 705 };
 706
 707 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 708 /*
 709  * Register an early platform driver of "earlyprintk" class.
 710  * ARCH platform code installs the driver and probes the early devices
 711  * The installation could rely on user specifying earlyprintk=xyx in cmd line
 712  * or it could be done independently, for all "earlyprintk" class drivers.
 713  * [see arch/arc/plat-arcfpga/platform.c]
 714  */
 715 early_platform_init("earlyprintk", &arc_platform_driver);
 716
 717 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
 718
 719 static int __init arc_serial_init(void)
 720 {
 721         int ret;
 722
 723         ret = uart_register_driver(&arc_uart_driver);
 724         if (ret)
 725                 return ret;
 726
 727         ret = platform_driver_register(&arc_platform_driver);
 728         if (ret)
 729                 uart_unregister_driver(&arc_uart_driver);
 730
 731         return ret;
 732 }
 733
 734 static void __exit arc_serial_exit(void)
 735 {
 736         platform_driver_unregister(&arc_platform_driver);
 737         uart_unregister_driver(&arc_uart_driver);
 738 }
 739
 740 module_init(arc_serial_init);
 741 module_exit(arc_serial_exit);
 742
 743 MODULE_LICENSE("GPL");
 744 MODULE_ALIAS("plat-arcfpga/uart");
 745 MODULE_AUTHOR("Vineet Gupta");
 746 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");