drivers/tty/serial/21285.c

   1 /*
   2  * Driver for the serial port on the 21285 StrongArm-110 core logic chip.
   3  *
   4  * Based on drivers/char/serial.c
   5  */
   6 #include <linux/module.h>
   7 #include <linux/tty.h>
   8 #include <linux/ioport.h>
   9 #include <linux/init.h>
  10 #include <linux/console.h>
  11 #include <linux/device.h>
  12 #include <linux/tty_flip.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/serial.h>
  15 #include <linux/io.h>
  16
  17 #include <asm/irq.h>
  18 #include <asm/mach-types.h>
  19 #include <asm/system_info.h>
  20 #include <asm/hardware/dec21285.h>
  21 #include <mach/hardware.h>
  22
  23 #define BAUD_BASE               (mem_fclk_21285/64)
  24
  25 #define SERIAL_21285_NAME       "ttyFB"
  26 #define SERIAL_21285_MAJOR      204
  27 #define SERIAL_21285_MINOR      4
  28
  29 #define RXSTAT_DUMMY_READ       0x80000000
  30 #define RXSTAT_FRAME            (1 << 0)
  31 #define RXSTAT_PARITY           (1 << 1)
  32 #define RXSTAT_OVERRUN          (1 << 2)
  33 #define RXSTAT_ANYERR           (RXSTAT_FRAME|RXSTAT_PARITY|RXSTAT_OVERRUN)
  34
  35 #define H_UBRLCR_BREAK          (1 << 0)
  36 #define H_UBRLCR_PARENB         (1 << 1)
  37 #define H_UBRLCR_PAREVN         (1 << 2)
  38 #define H_UBRLCR_STOPB          (1 << 3)
  39 #define H_UBRLCR_FIFO           (1 << 4)
  40
  41 static const char serial21285_name[] = "Footbridge UART";
  42
  43 #define tx_enabled(port)        ((port)->unused[0])
  44 #define rx_enabled(port)        ((port)->unused[1])
  45
  46 /*
  47  * The documented expression for selecting the divisor is:
  48  *  BAUD_BASE / baud - 1
  49  * However, typically BAUD_BASE is not divisible by baud, so
  50  * we want to select the divisor that gives us the minimum
  51  * error.  Therefore, we want:
  52  *  int(BAUD_BASE / baud - 0.5) ->
  53  *  int(BAUD_BASE / baud - (baud >> 1) / baud) ->
  54  *  int((BAUD_BASE - (baud >> 1)) / baud)
  55  */
  56
  57 static void serial21285_stop_tx(struct uart_port *port)
  58 {
  59         if (tx_enabled(port)) {
  60                 disable_irq_nosync(IRQ_CONTX);
  61                 tx_enabled(port) = 0;
  62         }
  63 }
  64
  65 static void serial21285_start_tx(struct uart_port *port)
  66 {
  67         if (!tx_enabled(port)) {
  68                 enable_irq(IRQ_CONTX);
  69                 tx_enabled(port) = 1;
  70         }
  71 }
  72
  73 static void serial21285_stop_rx(struct uart_port *port)
  74 {
  75         if (rx_enabled(port)) {
  76                 disable_irq_nosync(IRQ_CONRX);
  77                 rx_enabled(port) = 0;
  78         }
  79 }
  80
  81 static irqreturn_t serial21285_rx_chars(int irq, void *dev_id)
  82 {
  83         struct uart_port *port = dev_id;
  84         unsigned int status, ch, flag, rxs, max_count = 256;
  85
  86         status = *CSR_UARTFLG;
  87         while (!(status & 0x10) && max_count--) {
  88                 ch = *CSR_UARTDR;
  89                 flag = TTY_NORMAL;
  90                 port->icount.rx++;
  91
  92                 rxs = *CSR_RXSTAT | RXSTAT_DUMMY_READ;
  93                 if (unlikely(rxs & RXSTAT_ANYERR)) {
  94                         if (rxs & RXSTAT_PARITY)
  95                                 port->icount.parity++;
  96                         else if (rxs & RXSTAT_FRAME)
  97                                 port->icount.frame++;
  98                         if (rxs & RXSTAT_OVERRUN)
  99                                 port->icount.overrun++;
 100
 101                         rxs &= port->read_status_mask;
 102
 103                         if (rxs & RXSTAT_PARITY)
 104                                 flag = TTY_PARITY;
 105                         else if (rxs & RXSTAT_FRAME)
 106                                 flag = TTY_FRAME;
 107                 }
 108
 109                 uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
 110
 111                 status = *CSR_UARTFLG;
 112         }
 113         tty_flip_buffer_push(&port->state->port);
 114
 115         return IRQ_HANDLED;
 116 }
 117
 118 static irqreturn_t serial21285_tx_chars(int irq, void *dev_id)
 119 {
 120         struct uart_port *port = dev_id;
 121         struct circ_buf *xmit = &port->state->xmit;
 122         int count = 256;
 123
 124         if (port->x_char) {
 125                 *CSR_UARTDR = port->x_char;
 126                 port->icount.tx++;
 127                 port->x_char = 0;
 128                 goto out;
 129         }
 130         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 131                 serial21285_stop_tx(port);
 132                 goto out;
 133         }
 134
 135         do {
 136                 *CSR_UARTDR = xmit->buf[xmit->tail];
 137                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 138                 port->icount.tx++;
 139                 if (uart_circ_empty(xmit))
 140                         break;
 141         } while (--count > 0 && !(*CSR_UARTFLG & 0x20));
 142
 143         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 144                 uart_write_wakeup(port);
 145
 146         if (uart_circ_empty(xmit))
 147                 serial21285_stop_tx(port);
 148
 149  out:
 150         return IRQ_HANDLED;
 151 }
 152
 153 static unsigned int serial21285_tx_empty(struct uart_port *port)
 154 {
 155         return (*CSR_UARTFLG & 8) ? 0 : TIOCSER_TEMT;
 156 }
 157
 158 /* no modem control lines */
 159 static unsigned int serial21285_get_mctrl(struct uart_port *port)
 160 {
 161         return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 162 }
 163
 164 static void serial21285_set_mctrl(struct uart_port *port, unsigned int mctrl)
 165 {
 166 }
 167
 168 static void serial21285_break_ctl(struct uart_port *port, int break_state)
 169 {
 170         unsigned long flags;
 171         unsigned int h_lcr;
 172
 173         spin_lock_irqsave(&port->lock, flags);
 174         h_lcr = *CSR_H_UBRLCR;
 175         if (break_state)
 176                 h_lcr |= H_UBRLCR_BREAK;
 177         else
 178                 h_lcr &= ~H_UBRLCR_BREAK;
 179         *CSR_H_UBRLCR = h_lcr;
 180         spin_unlock_irqrestore(&port->lock, flags);
 181 }
 182
 183 static int serial21285_startup(struct uart_port *port)
 184 {
 185         int ret;
 186
 187         tx_enabled(port) = 1;
 188         rx_enabled(port) = 1;
 189
 190         ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
 191                           serial21285_name, port);
 192         if (ret == 0) {
 193                 ret = request_irq(IRQ_CONTX, serial21285_tx_chars, 0,
 194                                   serial21285_name, port);
 195                 if (ret)
 196                         free_irq(IRQ_CONRX, port);
 197         }
 198
 199         return ret;
 200 }
 201
 202 static void serial21285_shutdown(struct uart_port *port)
 203 {
 204         free_irq(IRQ_CONTX, port);
 205         free_irq(IRQ_CONRX, port);
 206 }
 207
 208 static void
 209 serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
 210                         struct ktermios *old)
 211 {
 212         unsigned long flags;
 213         unsigned int baud, quot, h_lcr, b;
 214
 215         /*
 216          * We don't support modem control lines.
 217          */
 218         termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
 219         termios->c_cflag |= CLOCAL;
 220
 221         /*
 222          * We don't support BREAK character recognition.
 223          */
 224         termios->c_iflag &= ~(IGNBRK | BRKINT);
 225
 226         /*
 227          * Ask the core to calculate the divisor for us.
 228          */
 229         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
 230         quot = uart_get_divisor(port, baud);
 231         b = port->uartclk / (16 * quot);
 232         tty_termios_encode_baud_rate(termios, b, b);
 233
 234         switch (termios->c_cflag & CSIZE) {
 235         case CS5:
 236                 h_lcr = 0x00;
 237                 break;
 238         case CS6:
 239                 h_lcr = 0x20;
 240                 break;
 241         case CS7:
 242                 h_lcr = 0x40;
 243                 break;
 244         default: /* CS8 */
 245                 h_lcr = 0x60;
 246                 break;
 247         }
 248
 249         if (termios->c_cflag & CSTOPB)
 250                 h_lcr |= H_UBRLCR_STOPB;
 251         if (termios->c_cflag & PARENB) {
 252                 h_lcr |= H_UBRLCR_PARENB;
 253                 if (!(termios->c_cflag & PARODD))
 254                         h_lcr |= H_UBRLCR_PAREVN;
 255         }
 256
 257         if (port->fifosize)
 258                 h_lcr |= H_UBRLCR_FIFO;
 259
 260         spin_lock_irqsave(&port->lock, flags);
 261
 262         /*
 263          * Update the per-port timeout.
 264          */
 265         uart_update_timeout(port, termios->c_cflag, baud);
 266
 267         /*
 268          * Which character status flags are we interested in?
 269          */
 270         port->read_status_mask = RXSTAT_OVERRUN;
 271         if (termios->c_iflag & INPCK)
 272                 port->read_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
 273
 274         /*
 275          * Which character status flags should we ignore?
 276          */
 277         port->ignore_status_mask = 0;
 278         if (termios->c_iflag & IGNPAR)
 279                 port->ignore_status_mask |= RXSTAT_FRAME | RXSTAT_PARITY;
 280         if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
 281                 port->ignore_status_mask |= RXSTAT_OVERRUN;
 282
 283         /*
 284          * Ignore all characters if CREAD is not set.
 285          */
 286         if ((termios->c_cflag & CREAD) == 0)
 287                 port->ignore_status_mask |= RXSTAT_DUMMY_READ;
 288
 289         quot -= 1;
 290
 291         *CSR_UARTCON = 0;
 292         *CSR_L_UBRLCR = quot & 0xff;
 293         *CSR_M_UBRLCR = (quot >> 8) & 0x0f;
 294         *CSR_H_UBRLCR = h_lcr;
 295         *CSR_UARTCON = 1;
 296
 297         spin_unlock_irqrestore(&port->lock, flags);
 298 }
 299
 300 static const char *serial21285_type(struct uart_port *port)
 301 {
 302         return port->type == PORT_21285 ? "DC21285" : NULL;
 303 }
 304
 305 static void serial21285_release_port(struct uart_port *port)
 306 {
 307         release_mem_region(port->mapbase, 32);
 308 }
 309
 310 static int serial21285_request_port(struct uart_port *port)
 311 {
 312         return request_mem_region(port->mapbase, 32, serial21285_name)
 313                          != NULL ? 0 : -EBUSY;
 314 }
 315
 316 static void serial21285_config_port(struct uart_port *port, int flags)
 317 {
 318         if (flags & UART_CONFIG_TYPE && serial21285_request_port(port) == 0)
 319                 port->type = PORT_21285;
 320 }
 321
 322 /*
 323  * verify the new serial_struct (for TIOCSSERIAL).
 324  */
 325 static int serial21285_verify_port(struct uart_port *port, struct serial_struct *ser)
 326 {
 327         int ret = 0;
 328         if (ser->type != PORT_UNKNOWN && ser->type != PORT_21285)
 329                 ret = -EINVAL;
 330         if (ser->irq <= 0)
 331                 ret = -EINVAL;
 332         if (ser->baud_base != port->uartclk / 16)
 333                 ret = -EINVAL;
 334         return ret;
 335 }
 336
 337 static struct uart_ops serial21285_ops = {
 338         .tx_empty       = serial21285_tx_empty,
 339         .get_mctrl      = serial21285_get_mctrl,
 340         .set_mctrl      = serial21285_set_mctrl,
 341         .stop_tx        = serial21285_stop_tx,
 342         .start_tx       = serial21285_start_tx,
 343         .stop_rx        = serial21285_stop_rx,
 344         .break_ctl      = serial21285_break_ctl,
 345         .startup        = serial21285_startup,
 346         .shutdown       = serial21285_shutdown,
 347         .set_termios    = serial21285_set_termios,
 348         .type           = serial21285_type,
 349         .release_port   = serial21285_release_port,
 350         .request_port   = serial21285_request_port,
 351         .config_port    = serial21285_config_port,
 352         .verify_port    = serial21285_verify_port,
 353 };
 354
 355 static struct uart_port serial21285_port = {
 356         .mapbase        = 0x42000160,
 357         .iotype         = UPIO_MEM,
 358         .irq            = 0,
 359         .fifosize       = 16,
 360         .ops            = &serial21285_ops,
 361         .flags          = UPF_BOOT_AUTOCONF,
 362 };
 363
 364 static void serial21285_setup_ports(void)
 365 {
 366         serial21285_port.uartclk = mem_fclk_21285 / 4;
 367 }
 368
 369 #ifdef CONFIG_SERIAL_21285_CONSOLE
 370 static void serial21285_console_putchar(struct uart_port *port, int ch)
 371 {
 372         while (*CSR_UARTFLG & 0x20)
 373                 barrier();
 374         *CSR_UARTDR = ch;
 375 }
 376
 377 static void
 378 serial21285_console_write(struct console *co, const char *s,
 379                           unsigned int count)
 380 {
 381         uart_console_write(&serial21285_port, s, count, serial21285_console_putchar);
 382 }
 383
 384 static void __init
 385 serial21285_get_options(struct uart_port *port, int *baud,
 386                         int *parity, int *bits)
 387 {
 388         if (*CSR_UARTCON == 1) {
 389                 unsigned int tmp;
 390
 391                 tmp = *CSR_H_UBRLCR;
 392                 switch (tmp & 0x60) {
 393                 case 0x00:
 394                         *bits = 5;
 395                         break;
 396                 case 0x20:
 397                         *bits = 6;
 398                         break;
 399                 case 0x40:
 400                         *bits = 7;
 401                         break;
 402                 default:
 403                 case 0x60:
 404                         *bits = 8;
 405                         break;
 406                 }
 407
 408                 if (tmp & H_UBRLCR_PARENB) {
 409                         *parity = 'o';
 410                         if (tmp & H_UBRLCR_PAREVN)
 411                                 *parity = 'e';
 412                 }
 413
 414                 tmp = *CSR_L_UBRLCR | (*CSR_M_UBRLCR << 8);
 415
 416                 *baud = port->uartclk / (16 * (tmp + 1));
 417         }
 418 }
 419
 420 static int __init serial21285_console_setup(struct console *co, char *options)
 421 {
 422         struct uart_port *port = &serial21285_port;
 423         int baud = 9600;
 424         int bits = 8;
 425         int parity = 'n';
 426         int flow = 'n';
 427
 428         if (machine_is_personal_server())
 429                 baud = 57600;
 430
 431         /*
 432          * Check whether an invalid uart number has been specified, and
 433          * if so, search for the first available port that does have
 434          * console support.
 435          */
 436         if (options)
 437                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 438         else
 439                 serial21285_get_options(port, &baud, &parity, &bits);
 440
 441         return uart_set_options(port, co, baud, parity, bits, flow);
 442 }
 443
 444 static struct uart_driver serial21285_reg;
 445
 446 static struct console serial21285_console =
 447 {
 448         .name           = SERIAL_21285_NAME,
 449         .write          = serial21285_console_write,
 450         .device         = uart_console_device,
 451         .setup          = serial21285_console_setup,
 452         .flags          = CON_PRINTBUFFER,
 453         .index          = -1,
 454         .data           = &serial21285_reg,
 455 };
 456
 457 static int __init rs285_console_init(void)
 458 {
 459         serial21285_setup_ports();
 460         register_console(&serial21285_console);
 461         return 0;
 462 }
 463 console_initcall(rs285_console_init);
 464
 465 #define SERIAL_21285_CONSOLE    &serial21285_console
 466 #else
 467 #define SERIAL_21285_CONSOLE    NULL
 468 #endif
 469
 470 static struct uart_driver serial21285_reg = {
 471         .owner                  = THIS_MODULE,
 472         .driver_name            = "ttyFB",
 473         .dev_name               = "ttyFB",
 474         .major                  = SERIAL_21285_MAJOR,
 475         .minor                  = SERIAL_21285_MINOR,
 476         .nr                     = 1,
 477         .cons                   = SERIAL_21285_CONSOLE,
 478 };
 479
 480 static int __init serial21285_init(void)
 481 {
 482         int ret;
 483
 484         printk(KERN_INFO "Serial: 21285 driver\n");
 485
 486         serial21285_setup_ports();
 487
 488         ret = uart_register_driver(&serial21285_reg);
 489         if (ret == 0)
 490                 uart_add_one_port(&serial21285_reg, &serial21285_port);
 491
 492         return ret;
 493 }
 494
 495 static void __exit serial21285_exit(void)
 496 {
 497         uart_remove_one_port(&serial21285_reg, &serial21285_port);
 498         uart_unregister_driver(&serial21285_reg);
 499 }
 500
 501 module_init(serial21285_init);
 502 module_exit(serial21285_exit);
 503
 504 MODULE_LICENSE("GPL");
 505 MODULE_DESCRIPTION("Intel Footbridge (21285) serial driver");
 506 MODULE_ALIAS_CHARDEV(SERIAL_21285_MAJOR, SERIAL_21285_MINOR);