target/linux/amazon/files/drivers/serial/amazon_asc.c

   1 /*
   2  *  Driver for AMAZONASC serial ports
   3  *
   4  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
   5  *  Based on drivers/serial/serial_s3c2400.c
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  * Copyright (C) 2004 Infineon IFAP DC COM CPE
  22  * Copyright (C) 2007 Felix Fietkau <nbd@openwrt.org>
  23  * Copyright (C) 2007 John Crispin <blogic@openwrt.org>
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/signal.h>
  29 #include <linux/sched.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/tty.h>
  32 #include <linux/tty_flip.h>
  33 #include <linux/major.h>
  34 #include <linux/string.h>
  35 #include <linux/fcntl.h>
  36 #include <linux/ptrace.h>
  37 #include <linux/ioport.h>
  38 #include <linux/mm.h>
  39 #include <linux/slab.h>
  40 #include <linux/init.h>
  41 #include <linux/circ_buf.h>
  42 #include <linux/serial.h>
  43 #include <linux/serial_core.h>
  44 #include <linux/console.h>
  45 #include <linux/sysrq.h>
  46 #include <linux/irq.h>
  47 #include <linux/platform_device.h>
  48
  49 #include <asm/system.h>
  50 #include <asm/io.h>
  51 #include <asm/uaccess.h>
  52 #include <asm/bitops.h>
  53 #include <asm/amazon/amazon.h>
  54 #include <asm/amazon/irq.h>
  55 #include <asm/amazon/serial.h>
  56
  57 #define PORT_AMAZONASC  111
  58
  59 #include <linux/serial_core.h>
  60
  61 #define UART_NR         1
  62
  63 #define UART_DUMMY_UER_RX 1
  64
  65 #define SERIAL_AMAZONASC_MAJOR  TTY_MAJOR
  66 #define CALLOUT_AMAZONASC_MAJOR TTYAUX_MAJOR
  67 #define SERIAL_AMAZONASC_MINOR  64
  68 #define SERIAL_AMAZONASC_NR     UART_NR
  69
  70 static void amazonasc_tx_chars(struct uart_port *port);
  71 static struct uart_port amazonasc_ports[UART_NR];
  72 static struct uart_driver amazonasc_reg;
  73 static unsigned int uartclk = 0;
  74 extern unsigned int amazon_get_fpi_hz(void);
  75
  76 static void amazonasc_stop_tx(struct uart_port *port)
  77 {
  78         /* fifo underrun shuts up after firing once */
  79         return;
  80 }
  81
  82 static void amazonasc_start_tx(struct uart_port *port)
  83 {
  84         unsigned long flags;
  85
  86         local_irq_save(flags);
  87         amazonasc_tx_chars(port);
  88         local_irq_restore(flags);
  89
  90         return;
  91 }
  92
  93 static void amazonasc_stop_rx(struct uart_port *port)
  94 {
  95         /* clear the RX enable bit */
  96         amazon_writel(ASCWHBCON_CLRREN, AMAZON_ASC_WHBCON);
  97 }
  98
  99 static void amazonasc_enable_ms(struct uart_port *port)
 100 {
 101         /* no modem signals */
 102         return;
 103 }
 104
 105 #include <linux/version.h>
 106
 107 static void
 108 amazonasc_rx_chars(struct uart_port *port)
 109 {
 110 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 31))
 111         struct tty_struct *tty = port->state->port.tty;
 112 #else
 113         struct tty_struct *tty = port->info->port.tty;
 114 #endif
 115         unsigned int ch = 0, rsr = 0, fifocnt;
 116
 117         fifocnt = amazon_readl(AMAZON_ASC_FSTAT) & ASCFSTAT_RXFFLMASK;
 118         while (fifocnt--)
 119         {
 120                 u8 flag = TTY_NORMAL;
 121                 ch = amazon_readl(AMAZON_ASC_RBUF);
 122                 rsr = (amazon_readl(AMAZON_ASC_CON) & ASCCON_ANY) | UART_DUMMY_UER_RX;
 123                 tty_flip_buffer_push(tty);
 124                 port->icount.rx++;
 125
 126                 /*
 127                  * Note that the error handling code is
 128                  * out of the main execution path
 129                  */
 130                 if (rsr & ASCCON_ANY) {
 131                         if (rsr & ASCCON_PE) {
 132                                 port->icount.parity++;
 133                                 amazon_writel_masked(AMAZON_ASC_WHBCON, ASCWHBCON_CLRPE, ASCWHBCON_CLRPE);
 134                         } else if (rsr & ASCCON_FE) {
 135                                 port->icount.frame++;
 136                                 amazon_writel_masked(AMAZON_ASC_WHBCON, ASCWHBCON_CLRFE, ASCWHBCON_CLRFE);
 137                         }
 138                         if (rsr & ASCCON_OE) {
 139                                 port->icount.overrun++;
 140                                 amazon_writel_masked(AMAZON_ASC_WHBCON, ASCWHBCON_CLROE, ASCWHBCON_CLROE);
 141                         }
 142
 143                         rsr &= port->read_status_mask;
 144
 145                         if (rsr & ASCCON_PE)
 146                                 flag = TTY_PARITY;
 147                         else if (rsr & ASCCON_FE)
 148                                 flag = TTY_FRAME;
 149                 }
 150
 151                 if ((rsr & port->ignore_status_mask) == 0)
 152                         tty_insert_flip_char(tty, ch, flag);
 153
 154                 if (rsr & ASCCON_OE)
 155                         /*
 156                          * Overrun is special, since it's reported
 157                          * immediately, and doesn't affect the current
 158                          * character
 159                          */
 160                         tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 161         }
 162         if (ch != 0)
 163                 tty_flip_buffer_push(tty);
 164
 165         return;
 166 }
 167
 168
 169 static void amazonasc_tx_chars(struct uart_port *port)
 170 {
 171 #if (LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 31))
 172         struct circ_buf *xmit = &port->state->xmit;
 173 #else
 174         struct circ_buf *xmit = &port->info->xmit;
 175 #endif
 176
 177         if (uart_tx_stopped(port)) {
 178                 amazonasc_stop_tx(port);
 179                 return;
 180         }
 181
 182         while (((amazon_readl(AMAZON_ASC_FSTAT) & ASCFSTAT_TXFFLMASK)
 183                         >> ASCFSTAT_TXFFLOFF) != AMAZONASC_TXFIFO_FULL)
 184         {
 185                 if (port->x_char) {
 186                         amazon_writel(port->x_char, AMAZON_ASC_TBUF);
 187                         port->icount.tx++;
 188                         port->x_char = 0;
 189                         continue;
 190                 }
 191
 192                 if (uart_circ_empty(xmit))
 193                         break;
 194
 195                 amazon_writel(xmit->buf[xmit->tail], AMAZON_ASC_TBUF);
 196                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 197                 port->icount.tx++;
 198         }
 199
 200         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 201                 uart_write_wakeup(port);
 202 }
 203
 204 static irqreturn_t amazonasc_tx_int(int irq, void *port)
 205 {
 206         amazon_writel(ASC_IRNCR_TIR, AMAZON_ASC_IRNCR1);
 207         amazonasc_start_tx(port);
 208
 209         /* clear any pending interrupts */
 210         amazon_writel_masked(AMAZON_ASC_WHBCON,
 211                         (ASCWHBCON_CLRPE | ASCWHBCON_CLRFE | ASCWHBCON_CLROE),
 212                         (ASCWHBCON_CLRPE | ASCWHBCON_CLRFE | ASCWHBCON_CLROE));
 213
 214         return IRQ_HANDLED;
 215 }
 216
 217 static irqreturn_t amazonasc_er_int(int irq, void *port)
 218 {
 219         /* clear any pending interrupts */
 220         amazon_writel_masked(AMAZON_ASC_WHBCON,
 221                         (ASCWHBCON_CLRPE | ASCWHBCON_CLRFE | ASCWHBCON_CLROE),
 222                         (ASCWHBCON_CLRPE | ASCWHBCON_CLRFE | ASCWHBCON_CLROE));
 223
 224         return IRQ_HANDLED;
 225 }
 226
 227 static irqreturn_t amazonasc_rx_int(int irq, void *port)
 228 {
 229         amazon_writel(ASC_IRNCR_RIR, AMAZON_ASC_IRNCR1);
 230         amazonasc_rx_chars((struct uart_port *) port);
 231         return IRQ_HANDLED;
 232 }
 233
 234 static u_int amazonasc_tx_empty(struct uart_port *port)
 235 {
 236         int status;
 237
 238         /*
 239          * FSTAT tells exactly how many bytes are in the FIFO.
 240          * The question is whether we really need to wait for all
 241          * 16 bytes to be transmitted before reporting that the
 242          * transmitter is empty.
 243          */
 244         status = amazon_readl(AMAZON_ASC_FSTAT) & ASCFSTAT_TXFFLMASK;
 245         return status ? 0 : TIOCSER_TEMT;
 246 }
 247
 248 static u_int amazonasc_get_mctrl(struct uart_port *port)
 249 {
 250         /* no modem control signals - the readme says to pretend all are set */
 251         return TIOCM_CTS|TIOCM_CAR|TIOCM_DSR;
 252 }
 253
 254 static void amazonasc_set_mctrl(struct uart_port *port, u_int mctrl)
 255 {
 256         /* no modem control - just return */
 257         return;
 258 }
 259
 260 static void amazonasc_break_ctl(struct uart_port *port, int break_state)
 261 {
 262         /* no way to send a break */
 263         return;
 264 }
 265
 266 static int amazonasc_startup(struct uart_port *port)
 267 {
 268         unsigned int con = 0;
 269         unsigned long flags;
 270         int retval;
 271
 272         /* this assumes: CON.BRS = CON.FDE = 0 */
 273         if (uartclk == 0)
 274                 uartclk = amazon_get_fpi_hz();
 275
 276         amazonasc_ports[0].uartclk = uartclk;
 277
 278         local_irq_save(flags);
 279
 280         /* this setup was probably already done in u-boot */
 281         /* ASC and GPIO Port 1 bits 3 and 4 share the same pins
 282          * P1.3 (RX) in, Alternate 10
 283          * P1.4 (TX) in, Alternate 10
 284          */
 285          amazon_writel_masked(AMAZON_GPIO_P1_DIR, 0x18, 0x10);  //P1.4 output, P1.3 input
 286          amazon_writel_masked(AMAZON_GPIO_P1_ALTSEL0, 0x18, 0x18);              //ALTSETL0 11
 287          amazon_writel_masked(AMAZON_GPIO_P1_ALTSEL1, 0x18, 0);         //ALTSETL1 00
 288          amazon_writel_masked(AMAZON_GPIO_P1_OD, 0x18, 0x10);
 289
 290         /* set up the CLC */
 291         amazon_writel_masked(AMAZON_ASC_CLC, AMAZON_ASC_CLC_DISS, 0);
 292         amazon_writel_masked(AMAZON_ASC_CLC, ASCCLC_RMCMASK, 1 << ASCCLC_RMCOFFSET);
 293
 294         /* asynchronous mode */
 295         con = ASCCON_M_8ASYNC | ASCCON_FEN | ASCCON_OEN | ASCCON_PEN;
 296
 297         /* choose the line - there's only one */
 298         amazon_writel(0, AMAZON_ASC_PISEL);
 299         amazon_writel(((AMAZONASC_TXFIFO_FL << ASCTXFCON_TXFITLOFF) & ASCTXFCON_TXFITLMASK) | ASCTXFCON_TXFEN | ASCTXFCON_TXFFLU,
 300                 AMAZON_ASC_TXFCON);
 301         amazon_writel(((AMAZONASC_RXFIFO_FL << ASCRXFCON_RXFITLOFF) & ASCRXFCON_RXFITLMASK) | ASCRXFCON_RXFEN | ASCRXFCON_RXFFLU,
 302                 AMAZON_ASC_RXFCON);
 303         wmb();
 304
 305         amazon_writel_masked(AMAZON_ASC_CON, con, con);
 306
 307         retval = request_irq(AMAZONASC_RIR, amazonasc_rx_int, 0, "asc_rx", port);
 308         if (retval){
 309                 printk("failed to request amazonasc_rx_int\n");
 310                 return retval;
 311         }
 312         retval = request_irq(AMAZONASC_TIR, amazonasc_tx_int, 0, "asc_tx", port);
 313         if (retval){
 314                 printk("failed to request amazonasc_tx_int\n");
 315                 goto err1;
 316         }
 317
 318         retval = request_irq(AMAZONASC_EIR, amazonasc_er_int, 0, "asc_er", port);
 319         if (retval){
 320                 printk("failed to request amazonasc_er_int\n");
 321                 goto err2;
 322         }
 323
 324         local_irq_restore(flags);
 325         return 0;
 326
 327 err2:
 328         free_irq(AMAZONASC_TIR, port);
 329
 330 err1:
 331         free_irq(AMAZONASC_RIR, port);
 332         local_irq_restore(flags);
 333         return retval;
 334 }
 335
 336 static void amazonasc_shutdown(struct uart_port *port)
 337 {
 338         free_irq(AMAZONASC_RIR, port);
 339         free_irq(AMAZONASC_TIR, port);
 340         free_irq(AMAZONASC_EIR, port);
 341         /*
 342          * disable the baudrate generator to disable the ASC
 343          */
 344         amazon_writel(0, AMAZON_ASC_CON);
 345
 346         /* flush and then disable the fifos */
 347         amazon_writel_masked(AMAZON_ASC_RXFCON, ASCRXFCON_RXFFLU, ASCRXFCON_RXFFLU);
 348         amazon_writel_masked(AMAZON_ASC_RXFCON, ASCRXFCON_RXFEN, 0);
 349         amazon_writel_masked(AMAZON_ASC_TXFCON, ASCTXFCON_TXFFLU, ASCTXFCON_TXFFLU);
 350         amazon_writel_masked(AMAZON_ASC_TXFCON, ASCTXFCON_TXFEN, 0);
 351 }
 352
 353 static void amazonasc_set_termios(struct uart_port *port, struct ktermios *new, struct ktermios *old)
 354 {
 355         unsigned int cflag;
 356         unsigned int iflag;
 357         unsigned int baud, quot;
 358         unsigned int con = 0;
 359         unsigned long flags;
 360
 361         cflag = new->c_cflag;
 362         iflag = new->c_iflag;
 363
 364         /* byte size and parity */
 365         switch (cflag & CSIZE) {
 366         /* 7 bits are always with parity */
 367         case CS7: con = ASCCON_M_7ASYNCPAR; break;
 368         /* the ASC only suports 7 and 8 bits */
 369         case CS5:
 370         case CS6:
 371         default:
 372                 if (cflag & PARENB)
 373                         con = ASCCON_M_8ASYNCPAR;
 374                 else
 375                         con = ASCCON_M_8ASYNC;
 376                 break;
 377         }
 378         if (cflag & CSTOPB)
 379                 con |= ASCCON_STP;
 380         if (cflag & PARENB) {
 381                 if (!(cflag & PARODD))
 382                         con &= ~ASCCON_ODD;
 383                 else
 384                         con |= ASCCON_ODD;
 385         }
 386
 387         port->read_status_mask = ASCCON_OE;
 388         if (iflag & INPCK)
 389                 port->read_status_mask |= ASCCON_FE | ASCCON_PE;
 390
 391         port->ignore_status_mask = 0;
 392         if (iflag & IGNPAR)
 393                 port->ignore_status_mask |= ASCCON_FE | ASCCON_PE;
 394
 395         if (iflag & IGNBRK) {
 396                 /*
 397                  * If we're ignoring parity and break indicators,
 398                  * ignore overruns too (for real raw support).
 399                  */
 400                 if (iflag & IGNPAR)
 401                         port->ignore_status_mask |= ASCCON_OE;
 402         }
 403
 404         /*
 405          * Ignore all characters if CREAD is not set.
 406          */
 407         if ((cflag & CREAD) == 0)
 408                 port->ignore_status_mask |= UART_DUMMY_UER_RX;
 409
 410         /* set error signals  - framing, parity  and overrun */
 411         con |= ASCCON_FEN;
 412         con |= ASCCON_OEN;
 413         con |= ASCCON_PEN;
 414         /* enable the receiver */
 415         con |= ASCCON_REN;
 416
 417         /* block the IRQs */
 418         local_irq_save(flags);
 419
 420         /* set up CON */
 421         amazon_writel(con, AMAZON_ASC_CON);
 422
 423         /* Set baud rate - take a divider of 2 into account */
 424     baud = uart_get_baud_rate(port, new, old, 0, port->uartclk/16);
 425         quot = uart_get_divisor(port, baud);
 426         quot = quot/2 - 1;
 427
 428         /* the next 3 probably already happened when we set CON above */
 429         /* disable the baudrate generator */
 430         amazon_writel_masked(AMAZON_ASC_CON, ASCCON_R, 0);
 431         /* make sure the fractional divider is off */
 432         amazon_writel_masked(AMAZON_ASC_CON, ASCCON_FDE, 0);
 433         /* set up to use divisor of 2 */
 434         amazon_writel_masked(AMAZON_ASC_CON, ASCCON_BRS, 0);
 435         /* now we can write the new baudrate into the register */
 436         amazon_writel(quot, AMAZON_ASC_BTR);
 437         /* turn the baudrate generator back on */
 438         amazon_writel_masked(AMAZON_ASC_CON, ASCCON_R, ASCCON_R);
 439
 440         local_irq_restore(flags);
 441 }
 442
 443 static const char *amazonasc_type(struct uart_port *port)
 444 {
 445         return port->type == PORT_AMAZONASC ? "AMAZONASC" : NULL;
 446 }
 447
 448 /*
 449  * Release the memory region(s) being used by 'port'
 450  */
 451 static void amazonasc_release_port(struct uart_port *port)
 452 {
 453         return;
 454 }
 455
 456 /*
 457  * Request the memory region(s) being used by 'port'
 458  */
 459 static int amazonasc_request_port(struct uart_port *port)
 460 {
 461         return 0;
 462 }
 463
 464 /*
 465  * Configure/autoconfigure the port.
 466  */
 467 static void amazonasc_config_port(struct uart_port *port, int flags)
 468 {
 469         if (flags & UART_CONFIG_TYPE) {
 470                 port->type = PORT_AMAZONASC;
 471                 amazonasc_request_port(port);
 472         }
 473 }
 474
 475 /*
 476  * verify the new serial_struct (for TIOCSSERIAL).
 477  */
 478 static int amazonasc_verify_port(struct uart_port *port, struct serial_struct *ser)
 479 {
 480         int ret = 0;
 481         if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMAZONASC)
 482                 ret = -EINVAL;
 483         if (ser->irq < 0 || ser->irq >= NR_IRQS)
 484                 ret = -EINVAL;
 485         if (ser->baud_base < 9600)
 486                 ret = -EINVAL;
 487         return ret;
 488 }
 489
 490 static struct uart_ops amazonasc_pops = {
 491         .tx_empty =             amazonasc_tx_empty,
 492         .set_mctrl =    amazonasc_set_mctrl,
 493         .get_mctrl =    amazonasc_get_mctrl,
 494         .stop_tx =              amazonasc_stop_tx,
 495         .start_tx =             amazonasc_start_tx,
 496         .stop_rx =              amazonasc_stop_rx,
 497         .enable_ms =    amazonasc_enable_ms,
 498         .break_ctl =    amazonasc_break_ctl,
 499         .startup =              amazonasc_startup,
 500         .shutdown =             amazonasc_shutdown,
 501         .set_termios =  amazonasc_set_termios,
 502         .type =                 amazonasc_type,
 503         .release_port = amazonasc_release_port,
 504         .request_port = amazonasc_request_port,
 505         .config_port =  amazonasc_config_port,
 506         .verify_port =  amazonasc_verify_port,
 507 };
 508
 509 static struct uart_port amazonasc_ports[UART_NR] = {
 510         {
 511                 membase:        (void *)AMAZON_ASC,
 512                 mapbase:        AMAZON_ASC,
 513                 iotype:         SERIAL_IO_MEM,
 514                 irq:            AMAZONASC_RIR, /* RIR */
 515                 uartclk:        0, /* filled in dynamically */
 516                 fifosize:       16,
 517                 unused:         { AMAZONASC_TIR, AMAZONASC_EIR}, /* xmit/error/xmit-buffer-empty IRQ */
 518                 type:           PORT_AMAZONASC,
 519                 ops:            &amazonasc_pops,
 520                 flags:          ASYNC_BOOT_AUTOCONF,
 521         },
 522 };
 523
 524 static void amazonasc_console_write(struct console *co, const char *s, u_int count)
 525 {
 526         int i, fifocnt;
 527         unsigned long flags;
 528         local_irq_save(flags);
 529         for (i = 0; i < count;)
 530         {
 531                 /* wait until the FIFO is not full */
 532                 do
 533                 {
 534                         fifocnt = (amazon_readl(AMAZON_ASC_FSTAT) & ASCFSTAT_TXFFLMASK)
 535                                         >> ASCFSTAT_TXFFLOFF;
 536                 } while (fifocnt == AMAZONASC_TXFIFO_FULL);
 537                 if (s[i] == '\0')
 538                 {
 539                         break;
 540                 }
 541                 if (s[i] == '\n')
 542                 {
 543                         amazon_writel('\r', AMAZON_ASC_TBUF);
 544                         do
 545                         {
 546                                 fifocnt = (amazon_readl(AMAZON_ASC_FSTAT) &
 547                                 ASCFSTAT_TXFFLMASK) >> ASCFSTAT_TXFFLOFF;
 548                         } while (fifocnt == AMAZONASC_TXFIFO_FULL);
 549                 }
 550                 amazon_writel(s[i], AMAZON_ASC_TBUF);
 551                 i++;
 552         }
 553
 554         local_irq_restore(flags);
 555 }
 556
 557 static void __init
 558 amazonasc_console_get_options(struct uart_port *port, int *baud, int *parity, int *bits)
 559 {
 560         u_int lcr_h;
 561
 562         lcr_h = amazon_readl(AMAZON_ASC_CON);
 563         /* do this only if the ASC is turned on */
 564         if (lcr_h & ASCCON_R) {
 565                 u_int quot, div, fdiv, frac;
 566
 567                 *parity = 'n';
 568                 if ((lcr_h & ASCCON_MODEMASK) == ASCCON_M_7ASYNCPAR ||
 569                             (lcr_h & ASCCON_MODEMASK) == ASCCON_M_8ASYNCPAR) {
 570                         if (lcr_h & ASCCON_ODD)
 571                                 *parity = 'o';
 572                         else
 573                                 *parity = 'e';
 574                 }
 575
 576                 if ((lcr_h & ASCCON_MODEMASK) == ASCCON_M_7ASYNCPAR)
 577                         *bits = 7;
 578                 else
 579                         *bits = 8;
 580
 581                 quot = amazon_readl(AMAZON_ASC_BTR) + 1;
 582
 583                 /* this gets hairy if the fractional divider is used */
 584                 if (lcr_h & ASCCON_FDE)
 585                 {
 586                         div = 1;
 587                         fdiv = amazon_readl(AMAZON_ASC_FDV);
 588                         if (fdiv == 0)
 589                                 fdiv = 512;
 590                         frac = 512;
 591                 }
 592                 else
 593                 {
 594                         div = lcr_h & ASCCON_BRS ? 3 : 2;
 595                         fdiv = frac = 1;
 596                 }
 597                 /*
 598                  * This doesn't work exactly because we use integer
 599                  * math to calculate baud which results in rounding
 600                  * errors when we try to go from quot -> baud !!
 601                  * Try to make this work for both the fractional divider
 602                  * and the simple divider. Also try to avoid rounding
 603                  * errors using integer math.
 604                  */
 605
 606                 *baud = frac * (port->uartclk / (div * 512 * 16 * quot));
 607                 if (*baud > 1100 && *baud < 2400)
 608                         *baud = 1200;
 609                 if (*baud > 2300 && *baud < 4800)
 610                         *baud = 2400;
 611                 if (*baud > 4700 && *baud < 9600)
 612                         *baud = 4800;
 613                 if (*baud > 9500 && *baud < 19200)
 614                         *baud = 9600;
 615                 if (*baud > 19000 && *baud < 38400)
 616                         *baud = 19200;
 617                 if (*baud > 38400 && *baud < 57600)
 618                         *baud = 38400;
 619                 if (*baud > 57600 && *baud < 115200)
 620                         *baud = 57600;
 621                 if (*baud > 115200 && *baud < 230400)
 622                         *baud = 115200;
 623         }
 624 }
 625
 626 static int __init amazonasc_console_setup(struct console *co, char *options)
 627 {
 628         struct uart_port *port;
 629         int baud = 115200;
 630         int bits = 8;
 631         int parity = 'n';
 632         int flow = 'n';
 633
 634         /* this assumes: CON.BRS = CON.FDE = 0 */
 635         if (uartclk == 0)
 636                 uartclk = amazon_get_fpi_hz();
 637         co->index = 0;
 638         port = &amazonasc_ports[0];
 639         amazonasc_ports[0].uartclk = uartclk;
 640         amazonasc_ports[0].type = PORT_AMAZONASC;
 641
 642         if (options){
 643                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 644         }
 645
 646         return uart_set_options(port, co, baud, parity, bits, flow);
 647 }
 648
 649 static struct uart_driver amazonasc_reg;
 650 static struct console amazonasc_console = {
 651         name:           "ttyS",
 652         write:          amazonasc_console_write,
 653         device:         uart_console_device,
 654         setup:          amazonasc_console_setup,
 655         flags:          CON_PRINTBUFFER,
 656         index:          -1,
 657         data:           &amazonasc_reg,
 658 };
 659
 660 static struct uart_driver amazonasc_reg = {
 661         .owner =                        THIS_MODULE,
 662         .driver_name =          "serial",
 663         .dev_name =                     "ttyS",
 664         .major =                        TTY_MAJOR,
 665         .minor =                        64,
 666         .nr =                           UART_NR,
 667         .cons =                         &amazonasc_console,
 668 };
 669
 670 static int __init amazon_asc_probe(struct platform_device *dev)
 671 {
 672         unsigned char res;
 673         uart_register_driver(&amazonasc_reg);
 674         res = uart_add_one_port(&amazonasc_reg, &amazonasc_ports[0]);
 675         return res;
 676 }
 677
 678 static int amazon_asc_remove(struct platform_device *dev)
 679 {
 680         uart_unregister_driver(&amazonasc_reg);
 681         return 0;
 682 }
 683
 684 static struct platform_driver amazon_asc_driver = {
 685         .probe = amazon_asc_probe,
 686         .remove = amazon_asc_remove,
 687         .driver = {
 688                 .name = "amazon_asc",
 689                 .owner = THIS_MODULE,
 690         },
 691 };
 692
 693 static int __init amazon_asc_init(void)
 694 {
 695         int ret = platform_driver_register(&amazon_asc_driver);
 696         if (ret)
 697                 printk(KERN_WARNING "amazon_asc: error registering platfom driver!\n");
 698         return ret;
 699 }
 700
 701 static void __exit amazon_asc_cleanup(void)
 702 {
 703         platform_driver_unregister(&amazon_asc_driver);
 704 }
 705
 706 module_init(amazon_asc_init);
 707 module_exit(amazon_asc_cleanup);
 708
 709 MODULE_AUTHOR("Gary Jennejohn, Felix Fietkau, John Crispin");
 710 MODULE_DESCRIPTION("MIPS AMAZONASC serial port driver");
 711 MODULE_LICENSE("GPL");
 712