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_irq.h>
  41 #include <linux/of_address.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(port, reg)      (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 };
 106
 107 #define to_arc_port(uport)  container_of(uport, struct arc_uart_port, port)
 108
 109 static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
 110
 111 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 112 static struct console arc_console;
 113 #endif
 114
 115 #define DRIVER_NAME     "arc-uart"
 116
 117 static struct uart_driver arc_uart_driver = {
 118         .owner          = THIS_MODULE,
 119         .driver_name    = DRIVER_NAME,
 120         .dev_name       = ARC_SERIAL_DEV_NAME,
 121         .major          = 0,
 122         .minor          = 0,
 123         .nr             = CONFIG_SERIAL_ARC_NR_PORTS,
 124 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 125         .cons           = &arc_console,
 126 #endif
 127 };
 128
 129 static void arc_serial_stop_rx(struct uart_port *port)
 130 {
 131         UART_RX_IRQ_DISABLE(port);
 132 }
 133
 134 static void arc_serial_stop_tx(struct uart_port *port)
 135 {
 136         while (!(UART_GET_STATUS(port) & TXEMPTY))
 137                 cpu_relax();
 138
 139         UART_TX_IRQ_DISABLE(port);
 140 }
 141
 142 /*
 143  * Return TIOCSER_TEMT when transmitter is not busy.
 144  */
 145 static unsigned int arc_serial_tx_empty(struct uart_port *port)
 146 {
 147         unsigned int stat;
 148
 149         stat = UART_GET_STATUS(port);
 150         if (stat & TXEMPTY)
 151                 return TIOCSER_TEMT;
 152
 153         return 0;
 154 }
 155
 156 /*
 157  * Driver internal routine, used by both tty(serial core) as well as tx-isr
 158  *  -Called under spinlock in either cases
 159  *  -also tty->stopped has already been checked
 160  *     = by uart_start( ) before calling us
 161  *     = tx_ist checks that too before calling
 162  */
 163 static void arc_serial_tx_chars(struct uart_port *port)
 164 {
 165         struct circ_buf *xmit = &port->state->xmit;
 166         int sent = 0;
 167         unsigned char ch;
 168
 169         if (unlikely(port->x_char)) {
 170                 UART_SET_DATA(port, port->x_char);
 171                 port->icount.tx++;
 172                 port->x_char = 0;
 173                 sent = 1;
 174         } else if (!uart_circ_empty(xmit)) {
 175                 ch = xmit->buf[xmit->tail];
 176                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 177                 port->icount.tx++;
 178                 while (!(UART_GET_STATUS(port) & TXEMPTY))
 179                         cpu_relax();
 180                 UART_SET_DATA(port, ch);
 181                 sent = 1;
 182         }
 183
 184         /*
 185          * If num chars in xmit buffer are too few, ask tty layer for more.
 186          * By Hard ISR to schedule processing in software interrupt part
 187          */
 188         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 189                 uart_write_wakeup(port);
 190
 191         if (sent)
 192                 UART_TX_IRQ_ENABLE(port);
 193 }
 194
 195 /*
 196  * port is locked and interrupts are disabled
 197  * uart_start( ) calls us under the port spinlock irqsave
 198  */
 199 static void arc_serial_start_tx(struct uart_port *port)
 200 {
 201         arc_serial_tx_chars(port);
 202 }
 203
 204 static void arc_serial_rx_chars(struct uart_port *port, unsigned int status)
 205 {
 206         unsigned int ch, flg = 0;
 207
 208         /*
 209          * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
 210          * is very subtle. Here's how ...
 211          * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
 212          * driver reads the DATA Reg and keeps doing that in a loop, until
 213          * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
 214          * before RX-EMPTY=0, implies some sort of buffering going on in the
 215          * controller, which is indeed the Rx-FIFO.
 216          */
 217         do {
 218                 /*
 219                  * This could be an Rx Intr for err (no data),
 220                  * so check err and clear that Intr first
 221                  */
 222                 if (unlikely(status & (RXOERR | RXFERR))) {
 223                         if (status & RXOERR) {
 224                                 port->icount.overrun++;
 225                                 flg = TTY_OVERRUN;
 226                                 UART_CLR_STATUS(port, RXOERR);
 227                         }
 228
 229                         if (status & RXFERR) {
 230                                 port->icount.frame++;
 231                                 flg = TTY_FRAME;
 232                                 UART_CLR_STATUS(port, RXFERR);
 233                         }
 234                 } else
 235                         flg = TTY_NORMAL;
 236
 237                 if (status & RXEMPTY)
 238                         continue;
 239
 240                 ch = UART_GET_DATA(port);
 241                 port->icount.rx++;
 242
 243                 if (!(uart_handle_sysrq_char(port, ch)))
 244                         uart_insert_char(port, status, RXOERR, ch, flg);
 245
 246                 spin_unlock(&port->lock);
 247                 tty_flip_buffer_push(&port->state->port);
 248                 spin_lock(&port->lock);
 249         } while (!((status = UART_GET_STATUS(port)) & RXEMPTY));
 250 }
 251
 252 /*
 253  * A note on the Interrupt handling state machine of this driver
 254  *
 255  * kernel printk writes funnel thru the console driver framework and in order
 256  * to keep things simple as well as efficient, it writes to UART in polled
 257  * mode, in one shot, and exits.
 258  *
 259  * OTOH, Userland output (via tty layer), uses interrupt based writes as there
 260  * can be undeterministic delay between char writes.
 261  *
 262  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
 263  * disabled.
 264  *
 265  * When tty has some data to send out, serial core calls driver's start_tx
 266  * which
 267  *   -checks-if-tty-buffer-has-char-to-send
 268  *   -writes-data-to-uart
 269  *   -enable-tx-intr
 270  *
 271  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
 272  * The first thing Tx ISR does is disable further Tx interrupts (as this could
 273  * be the last char to send, before settling down into the quiet polled mode).
 274  * It then calls the exact routine used by tty layer write to send out any
 275  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
 276  * of no data, it remains disabled.
 277  * This is how the transmit state machine is dynamically switched on/off
 278  */
 279
 280 static irqreturn_t arc_serial_isr(int irq, void *dev_id)
 281 {
 282         struct uart_port *port = dev_id;
 283         unsigned int status;
 284
 285         status = UART_GET_STATUS(port);
 286
 287         /*
 288          * Single IRQ for both Rx (data available) Tx (room available) Interrupt
 289          * notifications from the UART Controller.
 290          * To demultiplex between the two, we check the relevant bits
 291          */
 292         if (status & RXIENB) {
 293
 294                 /* already in ISR, no need of xx_irqsave */
 295                 spin_lock(&port->lock);
 296                 arc_serial_rx_chars(port, status);
 297                 spin_unlock(&port->lock);
 298         }
 299
 300         if ((status & TXIENB) && (status & TXEMPTY)) {
 301
 302                 /* Unconditionally disable further Tx-Interrupts.
 303                  * will be enabled by tx_chars() if needed.
 304                  */
 305                 UART_TX_IRQ_DISABLE(port);
 306
 307                 spin_lock(&port->lock);
 308
 309                 if (!uart_tx_stopped(port))
 310                         arc_serial_tx_chars(port);
 311
 312                 spin_unlock(&port->lock);
 313         }
 314
 315         return IRQ_HANDLED;
 316 }
 317
 318 static unsigned int arc_serial_get_mctrl(struct uart_port *port)
 319 {
 320         /*
 321          * Pretend we have a Modem status reg and following bits are
 322          *  always set, to satify the serial core state machine
 323          *  (DSR) Data Set Ready
 324          *  (CTS) Clear To Send
 325          *  (CAR) Carrier Detect
 326          */
 327         return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 328 }
 329
 330 static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 331 {
 332         /* MCR not present */
 333 }
 334
 335 static void arc_serial_break_ctl(struct uart_port *port, int break_state)
 336 {
 337         /* ARC UART doesn't support sending Break signal */
 338 }
 339
 340 static int arc_serial_startup(struct uart_port *port)
 341 {
 342         /* Before we hook up the ISR, Disable all UART Interrupts */
 343         UART_ALL_IRQ_DISABLE(port);
 344
 345         if (request_irq(port->irq, arc_serial_isr, 0, "arc uart rx-tx", port)) {
 346                 dev_warn(port->dev, "Unable to attach ARC UART intr\n");
 347                 return -EBUSY;
 348         }
 349
 350         UART_RX_IRQ_ENABLE(port); /* Only Rx IRQ enabled to begin with */
 351
 352         return 0;
 353 }
 354
 355 /* This is not really needed */
 356 static void arc_serial_shutdown(struct uart_port *port)
 357 {
 358         free_irq(port->irq, port);
 359 }
 360
 361 static void
 362 arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
 363                        struct ktermios *old)
 364 {
 365         struct arc_uart_port *uart = to_arc_port(port);
 366         unsigned int baud, uartl, uarth, hw_val;
 367         unsigned long flags;
 368
 369         /*
 370          * Use the generic handler so that any specially encoded baud rates
 371          * such as SPD_xx flags or "%B0" can be handled
 372          * Max Baud I suppose will not be more than current 115K * 4
 373          * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
 374          * spread over two 8-bit registers
 375          */
 376         baud = uart_get_baud_rate(port, new, old, 0, 460800);
 377
 378         hw_val = port->uartclk / (uart->baud * 4) - 1;
 379         uartl = hw_val & 0xFF;
 380         uarth = (hw_val >> 8) & 0xFF;
 381
 382         spin_lock_irqsave(&port->lock, flags);
 383
 384         UART_ALL_IRQ_DISABLE(port);
 385
 386         UART_SET_BAUDL(port, uartl);
 387         UART_SET_BAUDH(port, uarth);
 388
 389         UART_RX_IRQ_ENABLE(port);
 390
 391         /*
 392          * UART doesn't support Parity/Hardware Flow Control;
 393          * Only supports 8N1 character size
 394          */
 395         new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
 396         new->c_cflag |= CS8;
 397
 398         if (old)
 399                 tty_termios_copy_hw(new, old);
 400
 401         /* Don't rewrite B0 */
 402         if (tty_termios_baud_rate(new))
 403                 tty_termios_encode_baud_rate(new, baud, baud);
 404
 405         uart_update_timeout(port, new->c_cflag, baud);
 406
 407         spin_unlock_irqrestore(&port->lock, flags);
 408 }
 409
 410 static const char *arc_serial_type(struct uart_port *port)
 411 {
 412         return port->type == PORT_ARC ? DRIVER_NAME : NULL;
 413 }
 414
 415 static void arc_serial_release_port(struct uart_port *port)
 416 {
 417 }
 418
 419 static int arc_serial_request_port(struct uart_port *port)
 420 {
 421         return 0;
 422 }
 423
 424 /*
 425  * Verify the new serial_struct (for TIOCSSERIAL).
 426  */
 427 static int
 428 arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 429 {
 430         if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)
 431                 return -EINVAL;
 432
 433         return 0;
 434 }
 435
 436 /*
 437  * Configure/autoconfigure the port.
 438  */
 439 static void arc_serial_config_port(struct uart_port *port, int flags)
 440 {
 441         if (flags & UART_CONFIG_TYPE)
 442                 port->type = PORT_ARC;
 443 }
 444
 445 #ifdef CONFIG_CONSOLE_POLL
 446
 447 static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
 448 {
 449         while (!(UART_GET_STATUS(port) & TXEMPTY))
 450                 cpu_relax();
 451
 452         UART_SET_DATA(port, chr);
 453 }
 454
 455 static int arc_serial_poll_getchar(struct uart_port *port)
 456 {
 457         unsigned char chr;
 458
 459         while (!(UART_GET_STATUS(port) & RXEMPTY))
 460                 cpu_relax();
 461
 462         chr = UART_GET_DATA(port);
 463         return chr;
 464 }
 465 #endif
 466
 467 static struct uart_ops arc_serial_pops = {
 468         .tx_empty       = arc_serial_tx_empty,
 469         .set_mctrl      = arc_serial_set_mctrl,
 470         .get_mctrl      = arc_serial_get_mctrl,
 471         .stop_tx        = arc_serial_stop_tx,
 472         .start_tx       = arc_serial_start_tx,
 473         .stop_rx        = arc_serial_stop_rx,
 474         .break_ctl      = arc_serial_break_ctl,
 475         .startup        = arc_serial_startup,
 476         .shutdown       = arc_serial_shutdown,
 477         .set_termios    = arc_serial_set_termios,
 478         .type           = arc_serial_type,
 479         .release_port   = arc_serial_release_port,
 480         .request_port   = arc_serial_request_port,
 481         .config_port    = arc_serial_config_port,
 482         .verify_port    = arc_serial_verify_port,
 483 #ifdef CONFIG_CONSOLE_POLL
 484         .poll_put_char = arc_serial_poll_putchar,
 485         .poll_get_char = arc_serial_poll_getchar,
 486 #endif
 487 };
 488
 489 #ifdef CONFIG_SERIAL_ARC_CONSOLE
 490
 491 static int arc_serial_console_setup(struct console *co, char *options)
 492 {
 493         struct uart_port *port;
 494         int baud = 115200;
 495         int bits = 8;
 496         int parity = 'n';
 497         int flow = 'n';
 498
 499         if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
 500                 return -ENODEV;
 501
 502         /*
 503          * The uart port backing the console (e.g. ttyARC1) might not have been
 504          * init yet. If so, defer the console setup to after the port.
 505          */
 506         port = &arc_uart_ports[co->index].port;
 507         if (!port->membase)
 508                 return -ENODEV;
 509
 510         if (options)
 511                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 512
 513         /*
 514          * Serial core will call port->ops->set_termios( )
 515          * which will set the baud reg
 516          */
 517         return uart_set_options(port, co, baud, parity, bits, flow);
 518 }
 519
 520 static void arc_serial_console_putchar(struct uart_port *port, int ch)
 521 {
 522         while (!(UART_GET_STATUS(port) & TXEMPTY))
 523                 cpu_relax();
 524
 525         UART_SET_DATA(port, (unsigned char)ch);
 526 }
 527
 528 /*
 529  * Interrupts are disabled on entering
 530  */
 531 static void arc_serial_console_write(struct console *co, const char *s,
 532                                      unsigned int count)
 533 {
 534         struct uart_port *port = &arc_uart_ports[co->index].port;
 535         unsigned long flags;
 536
 537         spin_lock_irqsave(&port->lock, flags);
 538         uart_console_write(port, s, count, arc_serial_console_putchar);
 539         spin_unlock_irqrestore(&port->lock, flags);
 540 }
 541
 542 static struct console arc_console = {
 543         .name   = ARC_SERIAL_DEV_NAME,
 544         .write  = arc_serial_console_write,
 545         .device = uart_console_device,
 546         .setup  = arc_serial_console_setup,
 547         .flags  = CON_PRINTBUFFER,
 548         .index  = -1,
 549         .data   = &arc_uart_driver
 550 };
 551
 552 static __init void arc_early_serial_write(struct console *con, const char *s,
 553                                           unsigned int n)
 554 {
 555         struct earlycon_device *dev = con->data;
 556
 557         uart_console_write(&dev->port, s, n, arc_serial_console_putchar);
 558 }
 559
 560 static int __init arc_early_console_setup(struct earlycon_device *dev,
 561                                           const char *opt)
 562 {
 563         struct uart_port *port = &dev->port;
 564         unsigned int l, h, hw_val;
 565
 566         if (!dev->port.membase)
 567                 return -ENODEV;
 568
 569         hw_val = port->uartclk / (dev->baud * 4) - 1;
 570         l = hw_val & 0xFF;
 571         h = (hw_val >> 8) & 0xFF;
 572
 573         UART_SET_BAUDL(port, l);
 574         UART_SET_BAUDH(port, h);
 575
 576         dev->con->write = arc_early_serial_write;
 577         return 0;
 578 }
 579 EARLYCON_DECLARE(arc_uart, arc_early_console_setup);
 580 OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart", arc_early_console_setup);
 581
 582 #endif  /* CONFIG_SERIAL_ARC_CONSOLE */
 583
 584 static int arc_serial_probe(struct platform_device *pdev)
 585 {
 586         struct device_node *np = pdev->dev.of_node;
 587         struct arc_uart_port *uart;
 588         struct uart_port *port;
 589         int dev_id;
 590         u32 val;
 591
 592         /* no device tree device */
 593         if (!np)
 594                 return -ENODEV;
 595
 596         dev_id = of_alias_get_id(np, "serial");
 597         if (dev_id < 0)
 598                 dev_id = 0;
 599
 600         uart = &arc_uart_ports[dev_id];
 601         port = &uart->port;
 602
 603         if (of_property_read_u32(np, "clock-frequency", &val)) {
 604                 dev_err(&pdev->dev, "clock-frequency property NOTset\n");
 605                 return -EINVAL;
 606         }
 607         port->uartclk = val;
 608
 609         if (of_property_read_u32(np, "current-speed", &val)) {
 610                 dev_err(&pdev->dev, "current-speed property NOT set\n");
 611                 return -EINVAL;
 612         }
 613         uart->baud = val;
 614
 615         port->membase = of_iomap(np, 0);
 616         if (!port->membase)
 617                 /* No point of dev_err since UART itself is hosed here */
 618                 return -ENXIO;
 619
 620         port->irq = irq_of_parse_and_map(np, 0);
 621
 622         port->dev = &pdev->dev;
 623         port->iotype = UPIO_MEM;
 624         port->flags = UPF_BOOT_AUTOCONF;
 625         port->line = dev_id;
 626         port->ops = &arc_serial_pops;
 627
 628         port->fifosize = ARC_UART_TX_FIFO_SIZE;
 629
 630         /*
 631          * uart_insert_char( ) uses it in decideding whether to ignore a
 632          * char or not. Explicitly setting it here, removes the subtelty
 633          */
 634         port->ignore_status_mask = 0;
 635
 636         return uart_add_one_port(&arc_uart_driver, &arc_uart_ports[dev_id].port);
 637 }
 638
 639 static int arc_serial_remove(struct platform_device *pdev)
 640 {
 641         /* This will never be called */
 642         return 0;
 643 }
 644
 645 static const struct of_device_id arc_uart_dt_ids[] = {
 646         { .compatible = "snps,arc-uart" },
 647         { /* Sentinel */ }
 648 };
 649 MODULE_DEVICE_TABLE(of, arc_uart_dt_ids);
 650
 651 static struct platform_driver arc_platform_driver = {
 652         .probe = arc_serial_probe,
 653         .remove = arc_serial_remove,
 654         .driver = {
 655                 .name = DRIVER_NAME,
 656                 .of_match_table  = arc_uart_dt_ids,
 657          },
 658 };
 659
 660 static int __init arc_serial_init(void)
 661 {
 662         int ret;
 663
 664         ret = uart_register_driver(&arc_uart_driver);
 665         if (ret)
 666                 return ret;
 667
 668         ret = platform_driver_register(&arc_platform_driver);
 669         if (ret)
 670                 uart_unregister_driver(&arc_uart_driver);
 671
 672         return ret;
 673 }
 674
 675 static void __exit arc_serial_exit(void)
 676 {
 677         platform_driver_unregister(&arc_platform_driver);
 678         uart_unregister_driver(&arc_uart_driver);
 679 }
 680
 681 module_init(arc_serial_init);
 682 module_exit(arc_serial_exit);
 683
 684 MODULE_LICENSE("GPL");
 685 MODULE_ALIAS("platform:" DRIVER_NAME);
 686 MODULE_AUTHOR("Vineet Gupta");
 687 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");