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 #include <linux/of.h>
  41 #include <linux/of_platform.h>
  42
  43 /*************************************
  44  * ARC UART Hardware Specs
  45  ************************************/
  46 #define ARC_UART_TX_FIFO_SIZE  1
  47
  48 /*
  49  * UART Register set (this is not a Standards Compliant IP)
  50  * Also each reg is Word aligned, but only 8 bits wide
  51  */
  52 #define R_ID0   0
  53 #define R_ID1   4
  54 #define R_ID2   8
  55 #define R_ID3   12
  56 #define R_DATA  16
  57 #define R_STS   20
  58 #define R_BAUDL 24
  59 #define R_BAUDH 28
  60
  61 /* Bits for UART Status Reg (R/W) */
  62 #define RXIENB  0x04    /* Receive Interrupt Enable */
  63 #define TXIENB  0x40    /* Transmit Interrupt Enable */
  64
  65 #define RXEMPTY 0x20    /* Receive FIFO Empty: No char receivede */
  66 #define TXEMPTY 0x80    /* Transmit FIFO Empty, thus char can be written into */
  67
  68 #define RXFULL  0x08    /* Receive FIFO full */
  69 #define RXFULL1 0x10    /* Receive FIFO has space for 1 char (tot space=4) */
  70
  71 #define RXFERR  0x01    /* Frame Error: Stop Bit not detected */
  72 #define RXOERR  0x02    /* OverFlow Err: Char recv but RXFULL still set */
  73
  74 /* Uart bit fiddling helpers: lowest level */
  75 #define RBASE(uart, reg)      (uart->port.membase + reg)
  76 #define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
  77 #define UART_REG_GET(u, r)    readb(RBASE(u, r))
  78
  79 #define UART_REG_OR(u, r, v)  UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
  80 #define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
  81
  82 /* Uart bit fiddling helpers: API level */
  83 #define UART_SET_DATA(uart, val)   UART_REG_SET(uart, R_DATA, val)
  84 #define UART_GET_DATA(uart)        UART_REG_GET(uart, R_DATA)
  85
  86 #define UART_SET_BAUDH(uart, val)  UART_REG_SET(uart, R_BAUDH, val)
  87 #define UART_SET_BAUDL(uart, val)  UART_REG_SET(uart, R_BAUDL, val)
  88
  89 #define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
  90 #define UART_GET_STATUS(uart)      UART_REG_GET(uart, R_STS)
  91
  92 #define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
  93 #define UART_RX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, RXIENB)
  94 #define UART_TX_IRQ_DISABLE(uart)  UART_REG_CLR(uart, R_STS, TXIENB)
  95
  96 #define UART_ALL_IRQ_ENABLE(uart)  UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
  97 #define UART_RX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, RXIENB)
  98 #define UART_TX_IRQ_ENABLE(uart)   UART_REG_OR(uart, R_STS, TXIENB)
  99
 100 #define ARC_SERIAL_DEV_NAME     "ttyARC"
 101
 102 struct arc_uart_port {
 103         struct uart_port port;
 104         unsigned long baud;
 105         int is_emulated;        /* H/w vs. Instruction Set Simulator */
 106 };
 107
 108 #define to_arc_port(uport)  container_of(uport, struct arc_uart_port, port)
 109
 110 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
 111
 112 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 113 static struct console arc_console;
 114 #endif
 115
 116 #define DRIVER_NAME     "arc-uart"
 117
 118 static struct uart_driver arc_uart_driver = {
 119         .owner          = THIS_MODULE,
 120         .driver_name    = DRIVER_NAME,
 121         .dev_name       = ARC_SERIAL_DEV_NAME,
 122         .major          = 0,
 123         .minor          = 0,
 124         .nr             = CONFIG_SERIAL_ARC_NR_PORTS,
 125 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 126         .cons           = &arc_console,
 127 #endif
 128 };
 129
 130 static void arc_serial_stop_rx(struct uart_port *port)
 131 {
 132         struct arc_uart_port *uart = to_arc_port(port);
 133
 134         UART_RX_IRQ_DISABLE(uart);
 135 }
 136
 137 static void arc_serial_stop_tx(struct uart_port *port)
 138 {
 139         struct arc_uart_port *uart = to_arc_port(port);
 140
 141         while (!(UART_GET_STATUS(uart) & TXEMPTY))
 142                 cpu_relax();
 143
 144         UART_TX_IRQ_DISABLE(uart);
 145 }
 146
 147 /*
 148  * Return TIOCSER_TEMT when transmitter is not busy.
 149  */
 150 static unsigned int arc_serial_tx_empty(struct uart_port *port)
 151 {
 152         struct arc_uart_port *uart = to_arc_port(port);
 153         unsigned int stat;
 154
 155         stat = UART_GET_STATUS(uart);
 156         if (stat & TXEMPTY)
 157                 return TIOCSER_TEMT;
 158
 159         return 0;
 160 }
 161
 162 /*
 163  * Driver internal routine, used by both tty(serial core) as well as tx-isr
 164  *  -Called under spinlock in either cases
 165  *  -also tty->stopped has already been checked
 166  *     = by uart_start( ) before calling us
 167  *     = tx_ist checks that too before calling
 168  */
 169 static void arc_serial_tx_chars(struct arc_uart_port *uart)
 170 {
 171         struct circ_buf *xmit = &uart->port.state->xmit;
 172         int sent = 0;
 173         unsigned char ch;
 174
 175         if (unlikely(uart->port.x_char)) {
 176                 UART_SET_DATA(uart, uart->port.x_char);
 177                 uart->port.icount.tx++;
 178                 uart->port.x_char = 0;
 179                 sent = 1;
 180         } else if (xmit->tail != xmit->head) {  /* TODO: uart_circ_empty */
 181                 ch = xmit->buf[xmit->tail];
 182                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 183                 uart->port.icount.tx++;
 184                 while (!(UART_GET_STATUS(uart) & TXEMPTY))
 185                         cpu_relax();
 186                 UART_SET_DATA(uart, ch);
 187                 sent = 1;
 188         }
 189
 190         /*
 191          * If num chars in xmit buffer are too few, ask tty layer for more.
 192          * By Hard ISR to schedule processing in software interrupt part
 193          */
 194         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 195                 uart_write_wakeup(&uart->port);
 196
 197         if (sent)
 198                 UART_TX_IRQ_ENABLE(uart);
 199 }
 200
 201 /*
 202  * port is locked and interrupts are disabled
 203  * uart_start( ) calls us under the port spinlock irqsave
 204  */
 205 static void arc_serial_start_tx(struct uart_port *port)
 206 {
 207         struct arc_uart_port *uart = to_arc_port(port);
 208
 209         arc_serial_tx_chars(uart);
 210 }
 211
 212 static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
 213 {
 214         unsigned int ch, flg = 0;
 215
 216         /*
 217          * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
 218          * is very subtle. Here's how ...
 219          * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
 220          * driver reads the DATA Reg and keeps doing that in a loop, until
 221          * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
 222          * before RX-EMPTY=0, implies some sort of buffering going on in the
 223          * controller, which is indeed the Rx-FIFO.
 224          */
 225         do {
 226                 /*
 227                  * This could be an Rx Intr for err (no data),
 228                  * so check err and clear that Intr first
 229                  */
 230                 if (unlikely(status & (RXOERR | RXFERR))) {
 231                         if (status & RXOERR) {
 232                                 uart->port.icount.overrun++;
 233                                 flg = TTY_OVERRUN;
 234                                 UART_CLR_STATUS(uart, RXOERR);
 235                         }
 236
 237                         if (status & RXFERR) {
 238                                 uart->port.icount.frame++;
 239                                 flg = TTY_FRAME;
 240                                 UART_CLR_STATUS(uart, RXFERR);
 241                         }
 242                 } else
 243                         flg = TTY_NORMAL;
 244
 245                 if (status & RXEMPTY)
 246                         continue;
 247
 248                 ch = UART_GET_DATA(uart);
 249                 uart->port.icount.rx++;
 250
 251                 if (!(uart_handle_sysrq_char(&uart->port, ch)))
 252                         uart_insert_char(&uart->port, status, RXOERR, ch, flg);
 253
 254                 spin_unlock(&uart->port.lock);
 255                 tty_flip_buffer_push(&uart->port.state->port);
 256                 spin_lock(&uart->port.lock);
 257         } while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
 258 }
 259
 260 /*
 261  * A note on the Interrupt handling state machine of this driver
 262  *
 263  * kernel printk writes funnel thru the console driver framework and in order
 264  * to keep things simple as well as efficient, it writes to UART in polled
 265  * mode, in one shot, and exits.
 266  *
 267  * OTOH, Userland output (via tty layer), uses interrupt based writes as there
 268  * can be undeterministic delay between char writes.
 269  *
 270  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
 271  * disabled.
 272  *
 273  * When tty has some data to send out, serial core calls driver's start_tx
 274  * which
 275  *   -checks-if-tty-buffer-has-char-to-send
 276  *   -writes-data-to-uart
 277  *   -enable-tx-intr
 278  *
 279  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
 280  * The first thing Tx ISR does is disable further Tx interrupts (as this could
 281  * be the last char to send, before settling down into the quiet polled mode).
 282  * It then calls the exact routine used by tty layer write to send out any
 283  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
 284  * of no data, it remains disabled.
 285  * This is how the transmit state machine is dynamically switched on/off
 286  */
 287
 288 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
 289 {
 290         struct arc_uart_port *uart = dev_id;
 291         unsigned int status;
 292
 293         status = UART_GET_STATUS(uart);
 294
 295         /*
 296          * Single IRQ for both Rx (data available) Tx (room available) Interrupt
 297          * notifications from the UART Controller.
 298          * To demultiplex between the two, we check the relevant bits
 299          */
 300         if (status & RXIENB) {
 301
 302                 /* already in ISR, no need of xx_irqsave */
 303                 spin_lock(&uart->port.lock);
 304                 arc_serial_rx_chars(uart, status);
 305                 spin_unlock(&uart->port.lock);
 306         }
 307
 308         if ((status & TXIENB) && (status & TXEMPTY)) {
 309
 310                 /* Unconditionally disable further Tx-Interrupts.
 311                  * will be enabled by tx_chars() if needed.
 312                  */
 313                 UART_TX_IRQ_DISABLE(uart);
 314
 315                 spin_lock(&uart->port.lock);
 316
 317                 if (!uart_tx_stopped(&uart->port))
 318                         arc_serial_tx_chars(uart);
 319
 320                 spin_unlock(&uart->port.lock);
 321         }
 322
 323         return IRQ_HANDLED;
 324 }
 325
 326 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
 327 {
 328         /*
 329          * Pretend we have a Modem status reg and following bits are
 330          *  always set, to satify the serial core state machine
 331          *  (DSR) Data Set Ready
 332          *  (CTS) Clear To Send
 333          *  (CAR) Carrier Detect
 334          */
 335         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 336 }
 337
 338 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 339 {
 340         /* MCR not present */
 341 }
 342
 343 /* Enable Modem Status Interrupts */
 344
 345 static void arc_serial_enable_ms(struct uart_port *port)
 346 {
 347         /* MSR not present */
 348 }
 349
 350 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
 351 {
 352         /* ARC UART doesn't support sending Break signal */
 353 }
 354
 355 static int arc_serial_startup(struct uart_port *port)
 356 {
 357         struct arc_uart_port *uart = to_arc_port(port);
 358
 359         /* Before we hook up the ISR, Disable all UART Interrupts */
 360         UART_ALL_IRQ_DISABLE(uart);
 361
 362         if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
 363                         uart)) {
 364                 dev_warn(uart->port.dev, "Unable to attach ARC UART intr\n");
 365                 return -EBUSY;
 366         }
 367
 368         UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
 369
 370         return 0;
 371 }
 372
 373 /* This is not really needed */
 374 static void arc_serial_shutdown(struct uart_port *port)
 375 {
 376         struct arc_uart_port *uart = to_arc_port(port);
 377         free_irq(uart->port.irq, uart);
 378 }
 379
 380 static void
 381 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
 382                        struct ktermios *old)
 383 {
 384         struct arc_uart_port *uart = to_arc_port(port);
 385         unsigned int baud, uartl, uarth, hw_val;
 386         unsigned long flags;
 387
 388         /*
 389          * Use the generic handler so that any specially encoded baud rates
 390          * such as SPD_xx flags or "%B0" can be handled
 391          * Max Baud I suppose will not be more than current 115K * 4
 392          * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
 393          * spread over two 8-bit registers
 394          */
 395         baud = uart_get_baud_rate(port, new, old, 0, 460800);
 396
 397         hw_val = port->uartclk / (uart->baud * 4) - 1;
 398         uartl = hw_val & 0xFF;
 399         uarth = (hw_val >> 8) & 0xFF;
 400
 401         /*
 402          * UART ISS(Instruction Set simulator) emulation has a subtle bug:
 403          * A existing value of Baudh = 0 is used as a indication to startup
 404          * it's internal state machine.
 405          * Thus if baudh is set to 0, 2 times, it chokes.
 406          * This happens with BAUD=115200 and the formaula above
 407          * Until that is fixed, when running on ISS, we will set baudh to !0
 408          */
 409         if (uart->is_emulated)
 410                 uarth = 1;
 411
 412         spin_lock_irqsave(&port->lock, flags);
 413
 414         UART_ALL_IRQ_DISABLE(uart);
 415
 416         UART_SET_BAUDL(uart, uartl);
 417         UART_SET_BAUDH(uart, uarth);
 418
 419         UART_RX_IRQ_ENABLE(uart);
 420
 421         /*
 422          * UART doesn't support Parity/Hardware Flow Control;
 423          * Only supports 8N1 character size
 424          */
 425         new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
 426         new->c_cflag |= CS8;
 427
 428         if (old)
 429                 tty_termios_copy_hw(new, old);
 430
 431         /* Don't rewrite B0 */
 432         if (tty_termios_baud_rate(new))
 433                 tty_termios_encode_baud_rate(new, baud, baud);
 434
 435         uart_update_timeout(port, new->c_cflag, baud);
 436
 437         spin_unlock_irqrestore(&port->lock, flags);
 438 }
 439
 440 static const char *arc_serial_type(struct uart_port *port)
 441 {
 442         struct arc_uart_port *uart = to_arc_port(port);
 443
 444         return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
 445 }
 446
 447 static void arc_serial_release_port(struct uart_port *port)
 448 {
 449 }
 450
 451 static int arc_serial_request_port(struct uart_port *port)
 452 {
 453         return 0;
 454 }
 455
 456 /*
 457  * Verify the new serial_struct (for TIOCSSERIAL).
 458  */
 459 static int
 460 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 461 {
 462         if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
 463                 return -EINVAL;
 464
 465         return 0;
 466 }
 467
 468 /*
 469  * Configure/autoconfigure the port.
 470  */
 471 static void arc_serial_config_port(struct uart_port *port, int flags)
 472 {
 473         struct arc_uart_port *uart = to_arc_port(port);
 474
 475         if (flags & UART_CONFIG_TYPE)
 476                 uart->port.type = PORT_ARC;
 477 }
 478
 479 #if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
 480
 481 static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
 482 {
 483         struct arc_uart_port *uart = to_arc_port(port);
 484
 485         while (!(UART_GET_STATUS(uart) & TXEMPTY))
 486                 cpu_relax();
 487
 488         UART_SET_DATA(uart, chr);
 489 }
 490 #endif
 491
 492 #ifdef CONFIG_CONSOLE_POLL
 493 static int arc_serial_poll_getchar(struct uart_port *port)
 494 {
 495         struct arc_uart_port *uart = to_arc_port(port);
 496         unsigned char chr;
 497
 498         while (!(UART_GET_STATUS(uart) & RXEMPTY))
 499                 cpu_relax();
 500
 501         chr = UART_GET_DATA(uart);
 502         return chr;
 503 }
 504 #endif
 505
 506 static struct uart_ops arc_serial_pops = {
 507         .tx_empty       = arc_serial_tx_empty,
 508         .set_mctrl      = arc_serial_set_mctrl,
 509         .get_mctrl      = arc_serial_get_mctrl,
 510         .stop_tx        = arc_serial_stop_tx,
 511         .start_tx       = arc_serial_start_tx,
 512         .stop_rx        = arc_serial_stop_rx,
 513         .enable_ms      = arc_serial_enable_ms,
 514         .break_ctl      = arc_serial_break_ctl,
 515         .startup        = arc_serial_startup,
 516         .shutdown       = arc_serial_shutdown,
 517         .set_termios    = arc_serial_set_termios,
 518         .type           = arc_serial_type,
 519         .release_port   = arc_serial_release_port,
 520         .request_port   = arc_serial_request_port,
 521         .config_port    = arc_serial_config_port,
 522         .verify_port    = arc_serial_verify_port,
 523 #ifdef CONFIG_CONSOLE_POLL
 524         .poll_put_char = arc_serial_poll_putchar,
 525         .poll_get_char = arc_serial_poll_getchar,
 526 #endif
 527 };
 528
 529 static int
 530 arc_uart_init_one(struct platform_device *pdev, int dev_id)
 531 {
 532         struct resource *res, *res2;
 533         unsigned long *plat_data;
 534         struct arc_uart_port *uart = &arc_uart_ports[dev_id];
 535
 536         plat_data = dev_get_platdata(&pdev->dev);
 537         if (!plat_data)
 538                 return -ENODEV;
 539
 540         uart->is_emulated = !!plat_data[0];     /* workaround ISS bug */
 541
 542         if (is_early_platform_device(pdev)) {
 543                 uart->port.uartclk = plat_data[1];
 544                 uart->baud = plat_data[2];
 545         } else {
 546                 struct device_node *np = pdev->dev.of_node;
 547                 u32 val;
 548
 549                 if (of_property_read_u32(np, "clock-frequency", &val)) {
 550                         dev_err(&pdev->dev, "clock-frequency property NOTset\n");
 551                         return -EINVAL;
 552                 }
 553                 uart->port.uartclk = val;
 554
 555                 if (of_property_read_u32(np, "current-speed", &val)) {
 556                         dev_err(&pdev->dev, "current-speed property NOT set\n");
 557                         return -EINVAL;
 558                 }
 559                 uart->baud = val;
 560         }
 561
 562         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 563         if (!res)
 564                 return -ENODEV;
 565
 566         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 567         if (!res2)
 568                 return -ENODEV;
 569
 570         uart->port.mapbase = res->start;
 571         uart->port.membase = ioremap_nocache(res->start, resource_size(res));
 572         if (!uart->port.membase)
 573                 /* No point of dev_err since UART itself is hosed here */
 574                 return -ENXIO;
 575
 576         uart->port.irq = res2->start;
 577         uart->port.dev = &pdev->dev;
 578         uart->port.iotype = UPIO_MEM;
 579         uart->port.flags = UPF_BOOT_AUTOCONF;
 580         uart->port.line = dev_id;
 581         uart->port.ops = &arc_serial_pops;
 582
 583         uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
 584
 585         /*
 586          * uart_insert_char( ) uses it in decideding whether to ignore a
 587          * char or not. Explicitly setting it here, removes the subtelty
 588          */
 589         uart->port.ignore_status_mask = 0;
 590
 591         return 0;
 592 }
 593
 594 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 595
 596 static int arc_serial_console_setup(struct console *co, char *options)
 597 {
 598         struct uart_port *port;
 599         int baud = 115200;
 600         int bits = 8;
 601         int parity = 'n';
 602         int flow = 'n';
 603
 604         if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
 605                 return -ENODEV;
 606
 607         /*
 608          * The uart port backing the console (e.g. ttyARC1) might not have been
 609          * init yet. If so, defer the console setup to after the port.
 610          */
 611         port = &arc_uart_ports[co->index].port;
 612         if (!port->membase)
 613                 return -ENODEV;
 614
 615         if (options)
 616                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 617
 618         /*
 619          * Serial core will call port->ops->set_termios( )
 620          * which will set the baud reg
 621          */
 622         return uart_set_options(port, co, baud, parity, bits, flow);
 623 }
 624
 625 static void arc_serial_console_putchar(struct uart_port *port, int ch)
 626 {
 627         arc_serial_poll_putchar(port, (unsigned char)ch);
 628 }
 629
 630 /*
 631  * Interrupts are disabled on entering
 632  */
 633 static void arc_serial_console_write(struct console *co, const char *s,
 634                                      unsigned int count)
 635 {
 636         struct uart_port *port = &arc_uart_ports[co->index].port;
 637         unsigned long flags;
 638
 639         spin_lock_irqsave(&port->lock, flags);
 640         uart_console_write(port, s, count, arc_serial_console_putchar);
 641         spin_unlock_irqrestore(&port->lock, flags);
 642 }
 643
 644 static struct console arc_console = {
 645         .name   = ARC_SERIAL_DEV_NAME,
 646         .write  = arc_serial_console_write,
 647         .device = uart_console_device,
 648         .setup  = arc_serial_console_setup,
 649         .flags  = CON_PRINTBUFFER,
 650         .index  = -1,
 651         .data   = &arc_uart_driver
 652 };
 653
 654 static __init void early_serial_write(struct console *con, const char *s,
 655                                         unsigned int n)
 656 {
 657         struct uart_port *port = &arc_uart_ports[con->index].port;
 658         unsigned int i;
 659
 660         for (i = 0; i < n; i++, s++) {
 661                 if (*s == '\n')
 662                         arc_serial_poll_putchar(port, '\r');
 663                 arc_serial_poll_putchar(port, *s);
 664         }
 665 }
 666
 667 static struct console arc_early_serial_console __initdata = {
 668         .name = "early_ARCuart",
 669         .write = early_serial_write,
 670         .flags = CON_PRINTBUFFER | CON_BOOT,
 671         .index = -1
 672 };
 673
 674 static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
 675 {
 676         int dev_id = pdev->id < 0 ? 0 : pdev->id;
 677         int rc;
 678
 679         arc_early_serial_console.index = dev_id;
 680
 681         rc = arc_uart_init_one(pdev, dev_id);
 682         if (rc)
 683                 panic("early console init failed\n");
 684
 685         arc_serial_console_setup(&arc_early_serial_console, NULL);
 686
 687         register_console(&arc_early_serial_console);
 688         return 0;
 689 }
 690 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
 691
 692 static int arc_serial_probe(struct platform_device *pdev)
 693 {
 694         int rc, dev_id;
 695         struct device_node *np = pdev->dev.of_node;
 696
 697         /* no device tree device */
 698         if (!np)
 699                 return -ENODEV;
 700
 701         dev_id = of_alias_get_id(np, "serial");
 702         if (dev_id < 0)
 703                 dev_id = 0;
 704
 705         rc = arc_uart_init_one(pdev, dev_id);
 706         if (rc)
 707                 return rc;
 708
 709         rc = uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port);
 710         return rc;
 711 }
 712
 713 static int arc_serial_remove(struct platform_device *pdev)
 714 {
 715         /* This will never be called */
 716         return 0;
 717 }
 718
 719 static const struct of_device_id arc_uart_dt_ids[] = {
 720         { .compatible = "snps,arc-uart" },
 721         { /* Sentinel */ }
 722 };
 723 MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
 724
 725 static struct platform_driver arc_platform_driver = {
 726         .probe = arc_serial_probe,
 727         .remove = arc_serial_remove,
 728         .driver = {
 729                 .name = DRIVER_NAME,
 730                 .owner = THIS_MODULE,
 731                 .of_match_table  = arc_uart_dt_ids,
 732          },
 733 };
 734
 735 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 736
 737 static struct platform_driver early_arc_platform_driver __initdata = {
 738         .probe = arc_serial_probe_earlyprintk,
 739         .remove = arc_serial_remove,
 740         .driver = {
 741                 .name = DRIVER_NAME,
 742                 .owner = THIS_MODULE,
 743          },
 744 };
 745 /*
 746  * Register an early platform driver of "earlyprintk" class.
 747  * ARCH platform code installs the driver and probes the early devices
 748  * The installation could rely on user specifying earlyprintk=xyx in cmd line
 749  * or it could be done independently, for all "earlyprintk" class drivers.
 750  * [see arch/arc/plat-arcfpga/platform.c]
 751  */
 752 early_platform_init("earlyprintk", &early_arc_platform_driver);
 753
 754 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
 755
 756 static int __init arc_serial_init(void)
 757 {
 758         int ret;
 759
 760         ret = uart_register_driver(&arc_uart_driver);
 761         if (ret)
 762                 return ret;
 763
 764         ret = platform_driver_register(&arc_platform_driver);
 765         if (ret)
 766                 uart_unregister_driver(&arc_uart_driver);
 767
 768         return ret;
 769 }
 770
 771 static void __exit arc_serial_exit(void)
 772 {
 773         platform_driver_unregister(&arc_platform_driver);
 774         uart_unregister_driver(&arc_uart_driver);
 775 }
 776
 777 module_init(arc_serial_init);
 778 module_exit(arc_serial_exit);
 779
 780 MODULE_LICENSE("GPL");
 781 MODULE_ALIAS("platform:" DRIVER_NAME);
 782 MODULE_AUTHOR("Vineet Gupta");
 783 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");