drivers/serial/bfin_sport_uart.c

   1 /*
   2  * File:        linux/drivers/serial/bfin_sport_uart.c
   3  *
   4  * Based on:    drivers/serial/bfin_5xx.c by Aubrey Li.
   5  * Author:      Roy Huang <roy.huang@analog.com>
   6  *
   7  * Created:     Nov 22, 2006
   8  * Copyright:   (c) 2006-2007 Analog Devices Inc.
   9  * Description: this driver enable SPORTs on Blackfin emulate UART.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, see the file COPYING, or write
  23  * to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  25  */
  26
  27 /*
  28  * This driver and the hardware supported are in term of EE-191 of ADI.
  29  * http://www.analog.com/UploadedFiles/Application_Notes/399447663EE191.pdf
  30  * This application note describe how to implement a UART on a Sharc DSP,
  31  * but this driver is implemented on Blackfin Processor.
  32  */
  33
  34 /* After reset, there is a prelude of low level pulse when transmit data first
  35  * time. No addtional pulse in following transmit.
  36  * According to document:
  37  * The SPORTs are ready to start transmitting or receiving data no later than
  38  * three serial clock cycles after they are enabled in the SPORTx_TCR1 or
  39  * SPORTx_RCR1 register. No serial clock cycles are lost from this point on.
  40  * The first internal frame sync will occur one frame sync delay after the
  41  * SPORTs are ready. External frame syncs can occur as soon as the SPORT is
  42  * ready.
  43  */
  44
  45 /* Thanks to Axel Alatalo <axel@rubico.se> for fixing sport rx bug. Sometimes
  46  * sport receives data incorrectly. The following is Axel's words.
  47  * As EE-191, sport rx samples 3 times of the UART baudrate and takes the
  48  * middle smaple of every 3 samples as the data bit. For a 8-N-1 UART setting,
  49  * 30 samples will be required for a byte. If transmitter sends a 1/3 bit short
  50  * byte due to buadrate drift, then the 30th sample of a byte, this sample is
  51  * also the third sample of the stop bit, will happens on the immediately
  52  * following start bit which will be thrown away and missed. Thus since parts
  53  * of the startbit will be missed and the receiver will begin to drift, the
  54  * effect accumulates over time until synchronization is lost.
  55  * If only require 2 samples of the stopbit (by sampling in total 29 samples),
  56  * then a to short byte as in the case above will be tolerated. Then the 1/3
  57  * early startbit will trigger a framesync since the last read is complete
  58  * after only 2/3 stopbit and framesync is active during the last 1/3 looking
  59  * for a possible early startbit. */
  60
  61 //#define DEBUG
  62
  63 #include <linux/module.h>
  64 #include <linux/ioport.h>
  65 #include <linux/init.h>
  66 #include <linux/console.h>
  67 #include <linux/sysrq.h>
  68 #include <linux/platform_device.h>
  69 #include <linux/tty.h>
  70 #include <linux/tty_flip.h>
  71 #include <linux/serial_core.h>
  72
  73 #include <asm/delay.h>
  74 #include <asm/portmux.h>
  75
  76 #include "bfin_sport_uart.h"
  77
  78 unsigned short bfin_uart_pin_req_sport0[] =
  79         {P_SPORT0_TFS, P_SPORT0_DTPRI, P_SPORT0_TSCLK, P_SPORT0_RFS, \
  80          P_SPORT0_DRPRI, P_SPORT0_RSCLK, P_SPORT0_DRSEC, P_SPORT0_DTSEC, 0};
  81
  82 unsigned short bfin_uart_pin_req_sport1[] =
  83         {P_SPORT1_TFS, P_SPORT1_DTPRI, P_SPORT1_TSCLK, P_SPORT1_RFS, \
  84         P_SPORT1_DRPRI, P_SPORT1_RSCLK, P_SPORT1_DRSEC, P_SPORT1_DTSEC, 0};
  85
  86 #define DRV_NAME "bfin-sport-uart"
  87
  88 struct sport_uart_port {
  89         struct uart_port        port;
  90         char                    *name;
  91
  92         int                     tx_irq;
  93         int                     rx_irq;
  94         int                     err_irq;
  95 };
  96
  97 static void sport_uart_tx_chars(struct sport_uart_port *up);
  98 static void sport_stop_tx(struct uart_port *port);
  99
 100 static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
 101 {
 102         pr_debug("%s value:%x\n", __FUNCTION__, value);
 103         /* Place a Start and Stop bit */
 104         __asm__ volatile (
 105                 "R2 = b#01111111100;\n\t"
 106                 "R3 = b#10000000001;\n\t"
 107                 "%0 <<= 2;\n\t"
 108                 "%0 = %0 & R2;\n\t"
 109                 "%0 = %0 | R3;\n\t"
 110                 :"=r"(value)
 111                 :"0"(value)
 112                 :"R2", "R3");
 113         pr_debug("%s value:%x\n", __FUNCTION__, value);
 114
 115         SPORT_PUT_TX(up, value);
 116 }
 117
 118 static inline unsigned int rx_one_byte(struct sport_uart_port *up)
 119 {
 120         unsigned int value, extract;
 121
 122         value = SPORT_GET_RX32(up);
 123         pr_debug("%s value:%x\n", __FUNCTION__, value);
 124
 125         /* Extract 8 bits data */
 126         __asm__ volatile (
 127                 "R5 = 0;\n\t"
 128                 "P0 = 8;\n\t"
 129                 "R1 = 0x1801(Z);\n\t"
 130                 "R3 = 0x0300(Z);\n\t"
 131                 "R4 = 0;\n\t"
 132                 "LSETUP(loop_s, loop_e) LC0 = P0;\nloop_s:\t"
 133                 "R2 = extract(%1, R1.L)(Z);\n\t"
 134                 "R2 <<= R4;\n\t"
 135                 "R5 = R5 | R2;\n\t"
 136                 "R1 = R1 - R3;\nloop_e:\t"
 137                 "R4 += 1;\n\t"
 138                 "%0 = R5;\n\t"
 139                 :"=r"(extract)
 140                 :"r"(value)
 141                 :"P0", "R1", "R2","R3","R4", "R5");
 142
 143         pr_debug("      extract:%x\n", extract);
 144         return extract;
 145 }
 146
 147 static int sport_uart_setup(struct sport_uart_port *up, int sclk, int baud_rate)
 148 {
 149         int tclkdiv, tfsdiv, rclkdiv;
 150
 151         /* Set TCR1 and TCR2 */
 152         SPORT_PUT_TCR1(up, (LTFS | ITFS | TFSR | TLSBIT | ITCLK));
 153         SPORT_PUT_TCR2(up, 10);
 154         pr_debug("%s TCR1:%x, TCR2:%x\n", __FUNCTION__, SPORT_GET_TCR1(up), SPORT_GET_TCR2(up));
 155
 156         /* Set RCR1 and RCR2 */
 157         SPORT_PUT_RCR1(up, (RCKFE | LARFS | LRFS | RFSR | IRCLK));
 158         SPORT_PUT_RCR2(up, 28);
 159         pr_debug("%s RCR1:%x, RCR2:%x\n", __FUNCTION__, SPORT_GET_RCR1(up), SPORT_GET_RCR2(up));
 160
 161         tclkdiv = sclk/(2 * baud_rate) - 1;
 162         tfsdiv = 12;
 163         rclkdiv = sclk/(2 * baud_rate * 3) - 1;
 164         SPORT_PUT_TCLKDIV(up, tclkdiv);
 165         SPORT_PUT_TFSDIV(up, tfsdiv);
 166         SPORT_PUT_RCLKDIV(up, rclkdiv);
 167         SSYNC();
 168         pr_debug("%s sclk:%d, baud_rate:%d, tclkdiv:%d, tfsdiv:%d, rclkdiv:%d\n",
 169                         __FUNCTION__, sclk, baud_rate, tclkdiv, tfsdiv, rclkdiv);
 170
 171         return 0;
 172 }
 173
 174 static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
 175 {
 176         struct sport_uart_port *up = dev_id;
 177         struct tty_struct *tty = up->port.info->port.tty;
 178         unsigned int ch;
 179
 180         do {
 181                 ch = rx_one_byte(up);
 182                 up->port.icount.rx++;
 183
 184                 if (uart_handle_sysrq_char(&up->port, ch))
 185                         ;
 186                 else
 187                         tty_insert_flip_char(tty, ch, TTY_NORMAL);
 188         } while (SPORT_GET_STAT(up) & RXNE);
 189         tty_flip_buffer_push(tty);
 190
 191         return IRQ_HANDLED;
 192 }
 193
 194 static irqreturn_t sport_uart_tx_irq(int irq, void *dev_id)
 195 {
 196         sport_uart_tx_chars(dev_id);
 197
 198         return IRQ_HANDLED;
 199 }
 200
 201 static irqreturn_t sport_uart_err_irq(int irq, void *dev_id)
 202 {
 203         struct sport_uart_port *up = dev_id;
 204         struct tty_struct *tty = up->port.info->port.tty;
 205         unsigned int stat = SPORT_GET_STAT(up);
 206
 207         /* Overflow in RX FIFO */
 208         if (stat & ROVF) {
 209                 up->port.icount.overrun++;
 210                 tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 211                 SPORT_PUT_STAT(up, ROVF); /* Clear ROVF bit */
 212         }
 213         /* These should not happen */
 214         if (stat & (TOVF | TUVF | RUVF)) {
 215                 printk(KERN_ERR "SPORT Error:%s %s %s\n",
 216                                 (stat & TOVF)?"TX overflow":"",
 217                                 (stat & TUVF)?"TX underflow":"",
 218                                 (stat & RUVF)?"RX underflow":"");
 219                 SPORT_PUT_TCR1(up, SPORT_GET_TCR1(up) & ~TSPEN);
 220                 SPORT_PUT_RCR1(up, SPORT_GET_RCR1(up) & ~RSPEN);
 221         }
 222         SSYNC();
 223
 224         return IRQ_HANDLED;
 225 }
 226
 227 /* Reqeust IRQ, Setup clock */
 228 static int sport_startup(struct uart_port *port)
 229 {
 230         struct sport_uart_port *up = (struct sport_uart_port *)port;
 231         char buffer[20];
 232         int retval;
 233
 234         pr_debug("%s enter\n", __FUNCTION__);
 235         memset(buffer, 20, '\0');
 236         snprintf(buffer, 20, "%s rx", up->name);
 237         retval = request_irq(up->rx_irq, sport_uart_rx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 238         if (retval) {
 239                 printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 240                 return retval;
 241         }
 242
 243         snprintf(buffer, 20, "%s tx", up->name);
 244         retval = request_irq(up->tx_irq, sport_uart_tx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 245         if (retval) {
 246                 printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 247                 goto fail1;
 248         }
 249
 250         snprintf(buffer, 20, "%s err", up->name);
 251         retval = request_irq(up->err_irq, sport_uart_err_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 252         if (retval) {
 253                 printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 254                 goto fail2;
 255         }
 256
 257         if (port->line) {
 258                 if (peripheral_request_list(bfin_uart_pin_req_sport1, DRV_NAME))
 259                         goto fail3;
 260         } else {
 261                 if (peripheral_request_list(bfin_uart_pin_req_sport0, DRV_NAME))
 262                         goto fail3;
 263         }
 264
 265         sport_uart_setup(up, get_sclk(), port->uartclk);
 266
 267         /* Enable receive interrupt */
 268         SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) | RSPEN));
 269         SSYNC();
 270
 271         return 0;
 272
 273
 274 fail3:
 275         printk(KERN_ERR DRV_NAME
 276                 ": Requesting Peripherals failed\n");
 277
 278         free_irq(up->err_irq, up);
 279 fail2:
 280         free_irq(up->tx_irq, up);
 281 fail1:
 282         free_irq(up->rx_irq, up);
 283
 284         return retval;
 285
 286 }
 287
 288 static void sport_uart_tx_chars(struct sport_uart_port *up)
 289 {
 290         struct circ_buf *xmit = &up->port.info->xmit;
 291
 292         if (SPORT_GET_STAT(up) & TXF)
 293                 return;
 294
 295         if (up->port.x_char) {
 296                 tx_one_byte(up, up->port.x_char);
 297                 up->port.icount.tx++;
 298                 up->port.x_char = 0;
 299                 return;
 300         }
 301
 302         if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
 303                 sport_stop_tx(&up->port);
 304                 return;
 305         }
 306
 307         while(!(SPORT_GET_STAT(up) & TXF) && !uart_circ_empty(xmit)) {
 308                 tx_one_byte(up, xmit->buf[xmit->tail]);
 309                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
 310                 up->port.icount.tx++;
 311         }
 312
 313         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 314                 uart_write_wakeup(&up->port);
 315 }
 316
 317 static unsigned int sport_tx_empty(struct uart_port *port)
 318 {
 319         struct sport_uart_port *up = (struct sport_uart_port *)port;
 320         unsigned int stat;
 321
 322         stat = SPORT_GET_STAT(up);
 323         pr_debug("%s stat:%04x\n", __FUNCTION__, stat);
 324         if (stat & TXHRE) {
 325                 return TIOCSER_TEMT;
 326         } else
 327                 return 0;
 328 }
 329
 330 static unsigned int sport_get_mctrl(struct uart_port *port)
 331 {
 332         pr_debug("%s enter\n", __FUNCTION__);
 333         return (TIOCM_CTS | TIOCM_CD | TIOCM_DSR);
 334 }
 335
 336 static void sport_set_mctrl(struct uart_port *port, unsigned int mctrl)
 337 {
 338         pr_debug("%s enter\n", __FUNCTION__);
 339 }
 340
 341 static void sport_stop_tx(struct uart_port *port)
 342 {
 343         struct sport_uart_port *up = (struct sport_uart_port *)port;
 344         unsigned int stat;
 345
 346         pr_debug("%s enter\n", __FUNCTION__);
 347
 348         stat = SPORT_GET_STAT(up);
 349         while(!(stat & TXHRE)) {
 350                 udelay(1);
 351                 stat = SPORT_GET_STAT(up);
 352         }
 353         /* Although the hold register is empty, last byte is still in shift
 354          * register and not sent out yet. If baud rate is lower than default,
 355          * delay should be longer. For example, if the baud rate is 9600,
 356          * the delay must be at least 2ms by experience */
 357         udelay(500);
 358
 359         SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
 360         SSYNC();
 361
 362         return;
 363 }
 364
 365 static void sport_start_tx(struct uart_port *port)
 366 {
 367         struct sport_uart_port *up = (struct sport_uart_port *)port;
 368
 369         pr_debug("%s enter\n", __FUNCTION__);
 370         /* Write data into SPORT FIFO before enable SPROT to transmit */
 371         sport_uart_tx_chars(up);
 372
 373         /* Enable transmit, then an interrupt will generated */
 374         SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) | TSPEN));
 375         SSYNC();
 376         pr_debug("%s exit\n", __FUNCTION__);
 377 }
 378
 379 static void sport_stop_rx(struct uart_port *port)
 380 {
 381         struct sport_uart_port *up = (struct sport_uart_port *)port;
 382
 383         pr_debug("%s enter\n", __FUNCTION__);
 384         /* Disable sport to stop rx */
 385         SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
 386         SSYNC();
 387 }
 388
 389 static void sport_enable_ms(struct uart_port *port)
 390 {
 391         pr_debug("%s enter\n", __FUNCTION__);
 392 }
 393
 394 static void sport_break_ctl(struct uart_port *port, int break_state)
 395 {
 396         pr_debug("%s enter\n", __FUNCTION__);
 397 }
 398
 399 static void sport_shutdown(struct uart_port *port)
 400 {
 401         struct sport_uart_port *up = (struct sport_uart_port *)port;
 402
 403         pr_debug("%s enter\n", __FUNCTION__);
 404
 405         /* Disable sport */
 406         SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
 407         SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
 408         SSYNC();
 409
 410         if (port->line) {
 411                 peripheral_free_list(bfin_uart_pin_req_sport1);
 412         } else {
 413                 peripheral_free_list(bfin_uart_pin_req_sport0);
 414         }
 415
 416         free_irq(up->rx_irq, up);
 417         free_irq(up->tx_irq, up);
 418         free_irq(up->err_irq, up);
 419 }
 420
 421 static void sport_set_termios(struct uart_port *port,
 422                 struct termios *termios, struct termios *old)
 423 {
 424         pr_debug("%s enter, c_cflag:%08x\n", __FUNCTION__, termios->c_cflag);
 425         uart_update_timeout(port, CS8 ,port->uartclk);
 426 }
 427
 428 static const char *sport_type(struct uart_port *port)
 429 {
 430         struct sport_uart_port *up = (struct sport_uart_port *)port;
 431
 432         pr_debug("%s enter\n", __FUNCTION__);
 433         return up->name;
 434 }
 435
 436 static void sport_release_port(struct uart_port *port)
 437 {
 438         pr_debug("%s enter\n", __FUNCTION__);
 439 }
 440
 441 static int sport_request_port(struct uart_port *port)
 442 {
 443         pr_debug("%s enter\n", __FUNCTION__);
 444         return 0;
 445 }
 446
 447 static void sport_config_port(struct uart_port *port, int flags)
 448 {
 449         struct sport_uart_port *up = (struct sport_uart_port *)port;
 450
 451         pr_debug("%s enter\n", __FUNCTION__);
 452         up->port.type = PORT_BFIN_SPORT;
 453 }
 454
 455 static int sport_verify_port(struct uart_port *port, struct serial_struct *ser)
 456 {
 457         pr_debug("%s enter\n", __FUNCTION__);
 458         return 0;
 459 }
 460
 461 struct uart_ops sport_uart_ops = {
 462         .tx_empty       = sport_tx_empty,
 463         .set_mctrl      = sport_set_mctrl,
 464         .get_mctrl      = sport_get_mctrl,
 465         .stop_tx        = sport_stop_tx,
 466         .start_tx       = sport_start_tx,
 467         .stop_rx        = sport_stop_rx,
 468         .enable_ms      = sport_enable_ms,
 469         .break_ctl      = sport_break_ctl,
 470         .startup        = sport_startup,
 471         .shutdown       = sport_shutdown,
 472         .set_termios    = sport_set_termios,
 473         .type           = sport_type,
 474         .release_port   = sport_release_port,
 475         .request_port   = sport_request_port,
 476         .config_port    = sport_config_port,
 477         .verify_port    = sport_verify_port,
 478 };
 479
 480 static struct sport_uart_port sport_uart_ports[] = {
 481         { /* SPORT 0 */
 482                 .name   = "SPORT0",
 483                 .tx_irq = IRQ_SPORT0_TX,
 484                 .rx_irq = IRQ_SPORT0_RX,
 485                 .err_irq= IRQ_SPORT0_ERROR,
 486                 .port   = {
 487                         .type           = PORT_BFIN_SPORT,
 488                         .iotype         = UPIO_MEM,
 489                         .membase        = (void __iomem *)SPORT0_TCR1,
 490                         .mapbase        = SPORT0_TCR1,
 491                         .irq            = IRQ_SPORT0_RX,
 492                         .uartclk        = CONFIG_SPORT_BAUD_RATE,
 493                         .fifosize       = 8,
 494                         .ops            = &sport_uart_ops,
 495                         .line           = 0,
 496                 },
 497         }, { /* SPORT 1 */
 498                 .name   = "SPORT1",
 499                 .tx_irq = IRQ_SPORT1_TX,
 500                 .rx_irq = IRQ_SPORT1_RX,
 501                 .err_irq= IRQ_SPORT1_ERROR,
 502                 .port   = {
 503                         .type           = PORT_BFIN_SPORT,
 504                         .iotype         = UPIO_MEM,
 505                         .membase        = (void __iomem *)SPORT1_TCR1,
 506                         .mapbase        = SPORT1_TCR1,
 507                         .irq            = IRQ_SPORT1_RX,
 508                         .uartclk        = CONFIG_SPORT_BAUD_RATE,
 509                         .fifosize       = 8,
 510                         .ops            = &sport_uart_ops,
 511                         .line           = 1,
 512                 },
 513         }
 514 };
 515
 516 static struct uart_driver sport_uart_reg = {
 517         .owner          = THIS_MODULE,
 518         .driver_name    = "SPORT-UART",
 519         .dev_name       = "ttySS",
 520         .major          = 204,
 521         .minor          = 84,
 522         .nr             = ARRAY_SIZE(sport_uart_ports),
 523         .cons           = NULL,
 524 };
 525
 526 static int sport_uart_suspend(struct platform_device *dev, pm_message_t state)
 527 {
 528         struct sport_uart_port *sport = platform_get_drvdata(dev);
 529
 530         pr_debug("%s enter\n", __FUNCTION__);
 531         if (sport)
 532                 uart_suspend_port(&sport_uart_reg, &sport->port);
 533
 534         return 0;
 535 }
 536
 537 static int sport_uart_resume(struct platform_device *dev)
 538 {
 539         struct sport_uart_port *sport = platform_get_drvdata(dev);
 540
 541         pr_debug("%s enter\n", __FUNCTION__);
 542         if (sport)
 543                 uart_resume_port(&sport_uart_reg, &sport->port);
 544
 545         return 0;
 546 }
 547
 548 static int sport_uart_probe(struct platform_device *dev)
 549 {
 550         pr_debug("%s enter\n", __FUNCTION__);
 551         sport_uart_ports[dev->id].port.dev = &dev->dev;
 552         uart_add_one_port(&sport_uart_reg, &sport_uart_ports[dev->id].port);
 553         platform_set_drvdata(dev, &sport_uart_ports[dev->id]);
 554
 555         return 0;
 556 }
 557
 558 static int sport_uart_remove(struct platform_device *dev)
 559 {
 560         struct sport_uart_port *sport = platform_get_drvdata(dev);
 561
 562         pr_debug("%s enter\n", __FUNCTION__);
 563         platform_set_drvdata(dev, NULL);
 564
 565         if (sport)
 566                 uart_remove_one_port(&sport_uart_reg, &sport->port);
 567
 568         return 0;
 569 }
 570
 571 static struct platform_driver sport_uart_driver = {
 572         .probe          = sport_uart_probe,
 573         .remove         = sport_uart_remove,
 574         .suspend        = sport_uart_suspend,
 575         .resume         = sport_uart_resume,
 576         .driver         = {
 577                 .name   = DRV_NAME,
 578         },
 579 };
 580
 581 static int __init sport_uart_init(void)
 582 {
 583         int ret;
 584
 585         pr_debug("%s enter\n", __FUNCTION__);
 586         ret = uart_register_driver(&sport_uart_reg);
 587         if (ret != 0) {
 588                 printk(KERN_ERR "Failed to register %s:%d\n",
 589                                 sport_uart_reg.driver_name, ret);
 590                 return ret;
 591         }
 592
 593         ret = platform_driver_register(&sport_uart_driver);
 594         if (ret != 0) {
 595                 printk(KERN_ERR "Failed to register sport uart driver:%d\n", ret);
 596                 uart_unregister_driver(&sport_uart_reg);
 597         }
 598
 599
 600         pr_debug("%s exit\n", __FUNCTION__);
 601         return ret;
 602 }
 603
 604 static void __exit sport_uart_exit(void)
 605 {
 606         pr_debug("%s enter\n", __FUNCTION__);
 607         platform_driver_unregister(&sport_uart_driver);
 608         uart_unregister_driver(&sport_uart_reg);
 609 }
 610
 611 module_init(sport_uart_init);
 612 module_exit(sport_uart_exit);
 613
 614 MODULE_LICENSE("GPL");