drivers/serial/21285.c

   1 /*
   2  * linux/drivers/char/21285.c
   3  *
   4  * Driver for the serial port on the 21285 StrongArm-110 core logic chip.
   5  *
   6  * Based on drivers/char/serial.c
   7  *
   8  *  $Id: 21285.c,v 1.37 2002/07/28 10:03:27 rmk Exp $
   9  */
  10 #include <linux/config.h>
  11 #include <linux/module.h>
  12 #include <linux/tty.h>
  13 #include <linux/ioport.h>
  14 #include <linux/init.h>
  15 #include <linux/console.h>
  16 #include <linux/device.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/serial_core.h>
  19 #include <linux/serial.h>
  20
  21 #include <asm/io.h>
  22 #include <asm/irq.h>
  23 #include <asm/mach-types.h>
  24 #include <asm/hardware/dec21285.h>
  25 #include <asm/hardware.h>
  26
  27 #define BAUD_BASE               (mem_fclk_21285/64)
  28
  29 #define SERIAL_21285_NAME       "ttyFB"
  30 #define SERIAL_21285_MAJOR      204
  31 #define SERIAL_21285_MINOR      4
  32
  33 #define RXSTAT_DUMMY_READ       0x80000000
  34 #define RXSTAT_FRAME            (1 << 0)
  35 #define RXSTAT_PARITY           (1 << 1)
  36 #define RXSTAT_OVERRUN          (1 << 2)
  37 #define RXSTAT_ANYERR           (RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
  38
  39 #define H_UBRLCR_BREAK          (1 << 0)
  40 #define H_UBRLCR_PARENB         (1 << 1)
  41 #define H_UBRLCR_PAREVN         (1 << 2)
  42 #define H_UBRLCR_STOPB          (1 << 3)
  43 #define H_UBRLCR_FIFO           (1 << 4)
  44
  45 static const char serial21285_name[] = "Footbridge UART";
  46
  47 #define tx_enabled(port)        ((port)->unused[0])
  48 #define rx_enabled(port)        ((port)->unused[1])
  49
  50 /*
  51  * The documented expression for selecting the divisor is:
  52  *  BAUD_BASE / baud - 1
  53  * However, typically BAUD_BASE is not divisible by baud, so
  54  * we want to select the divisor that gives us the minimum
  55  * error.  Therefore, we want:
  56  *  int(BAUD_BASE / baud - 0.5) ->
  57  *  int(BAUD_BASE / baud - (baud >> 1) / baud) ->
  58  *  int((BAUD_BASE - (baud >> 1)) / baud)
  59  */
  60
  61 static void
  62 serial21285_stop_tx(struct uart_port *port, unsigned int tty_stop)
  63 {
  64         if (tx_enabled(port)) {
  65                 disable_irq(IRQ_CONTX);
  66                 tx_enabled(port) = 0;
  67         }
  68 }
  69
  70 static void
  71 serial21285_start_tx(struct uart_port *port, unsigned int tty_start)
  72 {
  73         if (!tx_enabled(port)) {
  74                 enable_irq(IRQ_CONTX);
  75                 tx_enabled(port) = 1;
  76         }
  77 }
  78
  79 static void serial21285_stop_rx(struct uart_port *port)
  80 {
  81         if (rx_enabled(port)) {
  82                 disable_irq(IRQ_CONRX);
  83                 rx_enabled(port) = 0;
  84         }
  85 }
  86
  87 static void serial21285_enable_ms(struct uart_port *port)
  88 {
  89 }
  90
  91 static irqreturn_t serial21285_rx_chars(int irq, void *dev_id, struct pt_regs *regs)
  92 {
  93         struct uart_port *port = dev_id;
  94         struct tty_struct *tty = port->info->tty;
  95         unsigned int status, ch, flag, rxs, max_count = 256;
  96
  97         status = *CSR_UARTFLG;
  98         while (!(status & 0x10) && max_count--) {
  99                 if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
 100                         if (tty->low_latency)
 101                                 tty_flip_buffer_push(tty);
 102                         /*
 103                          * If this failed then we will throw away the
 104                          * bytes but must do so to clear interrupts
 105                          */
 106                 }
 107
 108                 ch = *CSR_UARTDR;
 109                 flag = TTY_NORMAL;
 110                 port->icount.rx++;
 111
 112                 rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
 113                 if (rxs & RXSTAT_ANYERR) {
 114                         if (rxs & RXSTAT_PARITY)
 115                                 port->icount.parity++;
 116                         else if (rxs & RXSTAT_FRAME)
 117                                 port->icount.frame++;
 118                         if (rxs & RXSTAT_OVERRUN)
 119                                 port->icount.overrun++;
 120
 121                         rxs &= port->read_status_mask;
 122
 123                         if (rxs & RXSTAT_PARITY)
 124                                 flag = TTY_PARITY;
 125                         else if (rxs & RXSTAT_FRAME)
 126                                 flag = TTY_FRAME;
 127                 }
 128
 129                 if ((rxs & port->ignore_status_mask) == 0) {
 130                         tty_insert_flip_char(tty, ch, flag);
 131                 }
 132                 if ((rxs & RXSTAT_OVERRUN) &&
 133                     tty->flip.count < TTY_FLIPBUF_SIZE) {
 134                         /*
 135                          * Overrun is special, since it's reported
 136                          * immediately, and doesn't affect the current
 137                          * character.
 138                          */
 139                         tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 140                 }
 141                 status = *CSR_UARTFLG;
 142         }
 143         tty_flip_buffer_push(tty);
 144
 145         return IRQ_HANDLED;
 146 }
 147
 148 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id, struct pt_regs *regs)
 149 {
 150         struct uart_port *port = dev_id;
 151         struct circ_buf *xmit = &port->info->xmit;
 152         int count = 256;
 153
 154         if (port->x_char) {
 155                 *CSR_UARTDR = port->x_char;
 156                 port->icount.tx++;
 157                 port->x_char = 0;
 158                 goto out;
 159         }
 160         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 161                 serial21285_stop_tx(port, 0);
 162                 goto out;
 163         }
 164
 165         do {
 166                 *CSR_UARTDR = xmit->buf[xmit->tail];
 167                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 168                 port->icount.tx++;
 169                 if (uart_circ_empty(xmit))
 170                         break;
 171         } while (--count > 0 && !(*CSR_UARTFLG & 0x20));
 172
 173         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 174                 uart_write_wakeup(port);
 175
 176         if (uart_circ_empty(xmit))
 177                 serial21285_stop_tx(port, 0);
 178
 179  out:
 180         return IRQ_HANDLED;
 181 }
 182
 183 static unsigned int serial21285_tx_empty(struct uart_port *port)
 184 {
 185         return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
 186 }
 187
 188 /* no modem control lines */
 189 static unsigned int serial21285_get_mctrl(struct uart_port *port)
 190 {
 191         return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 192 }
 193
 194 static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
 195 {
 196 }
 197
 198 static void serial21285_break_ctl(struct uart_port *port, int break_state)
 199 {
 200         unsigned long flags;
 201         unsigned int h_lcr;
 202
 203         spin_lock_irqsave(&port->lock, flags);
 204         h_lcr = *CSR_H_UBRLCR;
 205         if (break_state)
 206                 h_lcr |= H_UBRLCR_BREAK;
 207         else
 208                 h_lcr &= ~H_UBRLCR_BREAK;
 209         *CSR_H_UBRLCR = h_lcr;
 210         spin_unlock_irqrestore(&port->lock, flags);
 211 }
 212
 213 static int serial21285_startup(struct uart_port *port)
 214 {
 215         int ret;
 216
 217         tx_enabled(port) = 1;
 218         rx_enabled(port) = 1;
 219
 220         ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
 221                           serial21285_name, port);
 222         if (ret == 0) {
 223                 ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
 224                                   serial21285_name, port);
 225                 if (ret)
 226                         free_irq(IRQ_CONRX, port);
 227         }
 228
 229         return ret;
 230 }
 231
 232 static void serial21285_shutdown(struct uart_port *port)
 233 {
 234         free_irq(IRQ_CONTX, port);
 235         free_irq(IRQ_CONRX, port);
 236 }
 237
 238 static void
 239 serial21285_set_termios(struct uart_port *port, struct termios *termios,
 240                         struct termios *old)
 241 {
 242         unsigned long flags;
 243         unsigned int baud, quot, h_lcr;
 244
 245         /*
 246          * We don't support modem control lines.
 247          */
 248         termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
 249         termios->c_cflag |= CLOCAL;
 250
 251         /*
 252          * We don't support BREAK character recognition.
 253          */
 254         termios->c_iflag &= ~(IGNBRK | BRKINT);
 255
 256         /*
 257          * Ask the core to calculate the divisor for us.
 258          */
 259         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
 260         quot = uart_get_divisor(port, baud);
 261
 262         switch (termios->c_cflag & CSIZE) {
 263         case CS5:
 264                 h_lcr = 0x00;
 265                 break;
 266         case CS6:
 267                 h_lcr = 0x20;
 268                 break;
 269         case CS7:
 270                 h_lcr = 0x40;
 271                 break;
 272         default: /* CS8 */
 273                 h_lcr = 0x60;
 274                 break;
 275         }
 276
 277         if (termios->c_cflag & CSTOPB)
 278                 h_lcr |= H_UBRLCR_STOPB;
 279         if (termios->c_cflag & PARENB) {
 280                 h_lcr |= H_UBRLCR_PARENB;
 281                 if (!(termios->c_cflag & PARODD))
 282                         h_lcr |= H_UBRLCR_PAREVN;
 283         }
 284
 285         if (port->fifosize)
 286                 h_lcr |= H_UBRLCR_FIFO;
 287
 288         spin_lock_irqsave(&port->lock, flags);
 289
 290         /*
 291          * Update the per-port timeout.
 292          */
 293         uart_update_timeout(port, termios->c_cflag, baud);
 294
 295         /*
 296          * Which character status flags are we interested in?
 297          */
 298         port->read_status_mask = RXSTAT_OVERRUN;
 299         if (termios->c_iflag & INPCK)
 300                 port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
 301
 302         /*
 303          * Which character status flags should we ignore?
 304          */
 305         port->ignore_status_mask = 0;
 306         if (termios->c_iflag & IGNPAR)
 307                 port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
 308         if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
 309                 port->ignore_status_mask |= RXSTAT_OVERRUN;
 310
 311         /*
 312          * Ignore all characters if CREAD is not set.
 313          */
 314         if ((termios->c_cflag & CREAD) == 0)
 315                 port->ignore_status_mask |= RXSTAT_DUMMY_READ;
 316
 317         quot -= 1;
 318
 319         *CSR_UARTCON = 0;
 320         *CSR_L_UBRLCR = quot & 0xff;
 321         *CSR_M_UBRLCR = (quot >> 8) & 0x0f;
 322         *CSR_H_UBRLCR = h_lcr;
 323         *CSR_UARTCON = 1;
 324
 325         spin_unlock_irqrestore(&port->lock, flags);
 326 }
 327
 328 static const char *serial21285_type(struct uart_port *port)
 329 {
 330         return port->type == PORT_21285 ? "DC21285" : NULL;
 331 }
 332
 333 static void serial21285_release_port(struct uart_port *port)
 334 {
 335         release_mem_region(port->mapbase, 32);
 336 }
 337
 338 static int serial21285_request_port(struct uart_port *port)
 339 {
 340         return request_mem_region(port->mapbase, 32, serial21285_name)
 341                          != NULL ? 0 : -EBUSY;
 342 }
 343
 344 static void serial21285_config_port(struct uart_port *port, int flags)
 345 {
 346         if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
 347                 port->type = PORT_21285;
 348 }
 349
 350 /*
 351  * verify the new serial_struct (for TIOCSSERIAL).
 352  */
 353 static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
 354 {
 355         int ret = 0;
 356         if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
 357                 ret = -EINVAL;
 358         if (ser->irq != NO_IRQ)
 359                 ret = -EINVAL;
 360         if (ser->baud_base != port->uartclk / 16)
 361                 ret = -EINVAL;
 362         return ret;
 363 }
 364
 365 static struct uart_ops serial21285_ops = {
 366         .tx_empty       = serial21285_tx_empty,
 367         .get_mctrl      = serial21285_get_mctrl,
 368         .set_mctrl      = serial21285_set_mctrl,
 369         .stop_tx        = serial21285_stop_tx,
 370         .start_tx       = serial21285_start_tx,
 371         .stop_rx        = serial21285_stop_rx,
 372         .enable_ms      = serial21285_enable_ms,
 373         .break_ctl      = serial21285_break_ctl,
 374         .startup        = serial21285_startup,
 375         .shutdown       = serial21285_shutdown,
 376         .set_termios    = serial21285_set_termios,
 377         .type           = serial21285_type,
 378         .release_port   = serial21285_release_port,
 379         .request_port   = serial21285_request_port,
 380         .config_port    = serial21285_config_port,
 381         .verify_port    = serial21285_verify_port,
 382 };
 383
 384 static struct uart_port serial21285_port = {
 385         .mapbase        = 0x42000160,
 386         .iotype         = SERIAL_IO_MEM,
 387         .irq            = NO_IRQ,
 388         .fifosize       = 16,
 389         .ops            = &serial21285_ops,
 390         .flags          = ASYNC_BOOT_AUTOCONF,
 391 };
 392
 393 static void serial21285_setup_ports(void)
 394 {
 395         serial21285_port.uartclk = mem_fclk_21285 / 4;
 396 }
 397
 398 #ifdef CONFIG_SERIAL_21285_CONSOLE
 399
 400 static void
 401 serial21285_console_write(struct console *co, const char *s,
 402                           unsigned int count)
 403 {
 404         int i;
 405
 406         for (i = 0; i < count; i++) {
 407                 while (*CSR_UARTFLG & 0x20)
 408                         barrier();
 409                 *CSR_UARTDR = s[i];
 410                 if (s[i] == '\n') {
 411                         while (*CSR_UARTFLG & 0x20)
 412                                 barrier();
 413                         *CSR_UARTDR = '\r';
 414                 }
 415         }
 416 }
 417
 418 static void __init
 419 serial21285_get_options(struct uart_port *port, int *baud,
 420                         int *parity, int *bits)
 421 {
 422         if (*CSR_UARTCON == 1) {
 423                 unsigned int tmp;
 424
 425                 tmp = *CSR_H_UBRLCR;
 426                 switch (tmp & 0x60) {
 427                 case 0x00:
 428                         *bits = 5;
 429                         break;
 430                 case 0x20:
 431                         *bits = 6;
 432                         break;
 433                 case 0x40:
 434                         *bits = 7;
 435                         break;
 436                 default:
 437                 case 0x60:
 438                         *bits = 8;
 439                         break;
 440                 }
 441
 442                 if (tmp & H_UBRLCR_PARENB) {
 443                         *parity = 'o';
 444                         if (tmp & H_UBRLCR_PAREVN)
 445                                 *parity = 'e';
 446                 }
 447
 448                 tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
 449
 450                 *baud = port->uartclk / (16 * (tmp + 1));
 451         }
 452 }
 453
 454 static int __init serial21285_console_setup(struct console *co, char *options)
 455 {
 456         struct uart_port *port = &serial21285_port;
 457         int baud = 9600;
 458         int bits = 8;
 459         int parity = 'n';
 460         int flow = 'n';
 461
 462         if (machine_is_personal_server())
 463                 baud = 57600;
 464
 465         /*
 466          * Check whether an invalid uart number has been specified, and
 467          * if so, search for the first available port that does have
 468          * console support.
 469          */
 470         if (options)
 471                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 472         else
 473                 serial21285_get_options(port, &baud, &parity, &bits);
 474
 475         return uart_set_options(port, co, baud, parity, bits, flow);
 476 }
 477
 478 extern struct uart_driver serial21285_reg;
 479
 480 static struct console serial21285_console =
 481 {
 482         .name           = SERIAL_21285_NAME,
 483         .write          = serial21285_console_write,
 484         .device         = uart_console_device,
 485         .setup          = serial21285_console_setup,
 486         .flags          = CON_PRINTBUFFER,
 487         .index          = -1,
 488         .data           = &serial21285_reg,
 489 };
 490
 491 static int __init rs285_console_init(void)
 492 {
 493         serial21285_setup_ports();
 494         register_console(&serial21285_console);
 495         return 0;
 496 }
 497 console_initcall(rs285_console_init);
 498
 499 #define SERIAL_21285_CONSOLE    &serial21285_console
 500 #else
 501 #define SERIAL_21285_CONSOLE    NULL
 502 #endif
 503
 504 static struct uart_driver serial21285_reg = {
 505         .owner                  = THIS_MODULE,
 506         .driver_name            = "ttyFB",
 507         .dev_name               = "ttyFB",
 508         .devfs_name             = "ttyFB",
 509         .major                  = SERIAL_21285_MAJOR,
 510         .minor                  = SERIAL_21285_MINOR,
 511         .nr                     = 1,
 512         .cons                   = SERIAL_21285_CONSOLE,
 513 };
 514
 515 static int __init serial21285_init(void)
 516 {
 517         int ret;
 518
 519         printk(KERN_INFO "Serial: 21285 driver $Revision: 1.37 $\n");
 520
 521         serial21285_setup_ports();
 522
 523         ret = uart_register_driver(&serial21285_reg);
 524         if (ret == 0)
 525                 uart_add_one_port(&serial21285_reg, &serial21285_port);
 526
 527         return ret;
 528 }
 529
 530 static void __exit serial21285_exit(void)
 531 {
 532         uart_remove_one_port(&serial21285_reg, &serial21285_port);
 533         uart_unregister_driver(&serial21285_reg);
 534 }
 535
 536 module_init(serial21285_init);
 537 module_exit(serial21285_exit);
 538
 539 MODULE_LICENSE("GPL");
 540 MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver $Revision: 1.37 $");
 541 MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);