drivers/serial/mux.c

   1 /*
   2 ** mux.c:
   3 **      serial driver for the Mux console found in some PA-RISC servers.
   4 **
   5 **      (c) Copyright 2002 Ryan Bradetich
   6 **      (c) Copyright 2002 Hewlett-Packard Company
   7 **
   8 ** This program is free software; you can redistribute it and/or modify
   9 ** it under the terms of the GNU General Public License as published by
  10 ** the Free Software Foundation; either version 2 of the License, or
  11 ** (at your option) any later version.
  12 **
  13 ** This Driver currently only supports the console (port 0) on the MUX.
  14 ** Additional work will be needed on this driver to enable the full
  15 ** functionality of the MUX.
  16 **
  17 */
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/tty.h>
  22 #include <linux/ioport.h>
  23 #include <linux/init.h>
  24 #include <linux/serial.h>
  25 #include <linux/console.h>
  26 #include <linux/slab.h>
  27 #include <linux/delay.h> /* for udelay */
  28 #include <linux/device.h>
  29 #include <asm/io.h>
  30 #include <asm/irq.h>
  31 #include <asm/parisc-device.h>
  32
  33 #ifdef CONFIG_MAGIC_SYSRQ
  34 #include <linux/sysrq.h>
  35 #define SUPPORT_SYSRQ
  36 #endif
  37
  38 #include <linux/serial_core.h>
  39
  40 #define MUX_OFFSET 0x800
  41 #define MUX_LINE_OFFSET 0x80
  42
  43 #define MUX_FIFO_SIZE 255
  44 #define MUX_POLL_DELAY (30 * HZ / 1000)
  45
  46 #define IO_DATA_REG_OFFSET 0x3c
  47 #define IO_DCOUNT_REG_OFFSET 0x40
  48
  49 #define MUX_EOFIFO(status) ((status & 0xF000) == 0xF000)
  50 #define MUX_STATUS(status) ((status & 0xF000) == 0x8000)
  51 #define MUX_BREAK(status) ((status & 0xF000) == 0x2000)
  52
  53 #define MUX_NR 256
  54 static unsigned int port_cnt = 0;
  55 static struct uart_port mux_ports[MUX_NR];
  56
  57 static struct uart_driver mux_driver = {
  58         .owner = THIS_MODULE,
  59         .driver_name = "ttyB",
  60         .dev_name = "ttyB",
  61         .major = MUX_MAJOR,
  62         .minor = 0,
  63         .nr = MUX_NR,
  64 };
  65
  66 static struct timer_list mux_timer;
  67
  68 #define UART_PUT_CHAR(p, c) __raw_writel((c), (unsigned long)(p)->membase + IO_DATA_REG_OFFSET)
  69 #define UART_GET_FIFO_CNT(p) __raw_readl((unsigned long)(p)->membase + IO_DCOUNT_REG_OFFSET)
  70 #define GET_MUX_PORTS(iodc_data) ((((iodc_data)[4] & 0xf0) >> 4) * 8) + 8
  71
  72 /**
  73  * mux_tx_empty - Check if the transmitter fifo is empty.
  74  * @port: Ptr to the uart_port.
  75  *
  76  * This function test if the transmitter fifo for the port
  77  * described by 'port' is empty.  If it is empty, this function
  78  * should return TIOCSER_TEMT, otherwise return 0.
  79  */
  80 static unsigned int mux_tx_empty(struct uart_port *port)
  81 {
  82         unsigned int cnt = __raw_readl((unsigned long)port->membase
  83                                 + IO_DCOUNT_REG_OFFSET);
  84
  85         return cnt ? 0 : TIOCSER_TEMT;
  86 }
  87
  88 /**
  89  * mux_set_mctrl - Set the current state of the modem control inputs.
  90  * @ports: Ptr to the uart_port.
  91  * @mctrl: Modem control bits.
  92  *
  93  * The Serial MUX does not support CTS, DCD or DSR so this function
  94  * is ignored.
  95  */
  96 static void mux_set_mctrl(struct uart_port *port, unsigned int mctrl)
  97 {
  98 }
  99
 100 /**
 101  * mux_get_mctrl - Returns the current state of modem control inputs.
 102  * @port: Ptr to the uart_port.
 103  *
 104  * The Serial MUX does not support CTS, DCD or DSR so these lines are
 105  * treated as permanently active.
 106  */
 107 static unsigned int mux_get_mctrl(struct uart_port *port)
 108 {
 109         return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 110 }
 111
 112 /**
 113  * mux_stop_tx - Stop transmitting characters.
 114  * @port: Ptr to the uart_port.
 115  *
 116  * The Serial MUX does not support this function.
 117  */
 118 static void mux_stop_tx(struct uart_port *port)
 119 {
 120 }
 121
 122 /**
 123  * mux_start_tx - Start transmitting characters.
 124  * @port: Ptr to the uart_port.
 125  *
 126  * The Serial Mux does not support this function.
 127  */
 128 static void mux_start_tx(struct uart_port *port)
 129 {
 130 }
 131
 132 /**
 133  * mux_stop_rx - Stop receiving characters.
 134  * @port: Ptr to the uart_port.
 135  *
 136  * The Serial Mux does not support this function.
 137  */
 138 static void mux_stop_rx(struct uart_port *port)
 139 {
 140 }
 141
 142 /**
 143  * mux_enable_ms - Enable modum status interrupts.
 144  * @port: Ptr to the uart_port.
 145  *
 146  * The Serial Mux does not support this function.
 147  */
 148 static void mux_enable_ms(struct uart_port *port)
 149 {
 150 }
 151
 152 /**
 153  * mux_break_ctl - Control the transmitssion of a break signal.
 154  * @port: Ptr to the uart_port.
 155  * @break_state: Raise/Lower the break signal.
 156  *
 157  * The Serial Mux does not support this function.
 158  */
 159 static void mux_break_ctl(struct uart_port *port, int break_state)
 160 {
 161 }
 162
 163 /**
 164  * mux_write - Write chars to the mux fifo.
 165  * @port: Ptr to the uart_port.
 166  *
 167  * This function writes all the data from the uart buffer to
 168  * the mux fifo.
 169  */
 170 static void mux_write(struct uart_port *port)
 171 {
 172         int count;
 173         struct circ_buf *xmit = &port->info->xmit;
 174
 175         if(port->x_char) {
 176                 UART_PUT_CHAR(port, port->x_char);
 177                 port->icount.tx++;
 178                 port->x_char = 0;
 179                 return;
 180         }
 181
 182         if(uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 183                 mux_stop_tx(port);
 184                 return;
 185         }
 186
 187         count = (port->fifosize) - UART_GET_FIFO_CNT(port);
 188         do {
 189                 UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 190                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 191                 port->icount.tx++;
 192                 if(uart_circ_empty(xmit))
 193                         break;
 194
 195         } while(--count > 0);
 196
 197         while(UART_GET_FIFO_CNT(port))
 198                 udelay(1);
 199
 200         if(uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 201                 uart_write_wakeup(port);
 202
 203         if (uart_circ_empty(xmit))
 204                 mux_stop_tx(port);
 205 }
 206
 207 /**
 208  * mux_read - Read chars from the mux fifo.
 209  * @port: Ptr to the uart_port.
 210  *
 211  * This reads all available data from the mux's fifo and pushes
 212  * the data to the tty layer.
 213  */
 214 static void mux_read(struct uart_port *port)
 215 {
 216         int data;
 217         struct tty_struct *tty = port->info->tty;
 218         __u32 start_count = port->icount.rx;
 219
 220         while(1) {
 221                 data = __raw_readl((unsigned long)port->membase
 222                                                 + IO_DATA_REG_OFFSET);
 223
 224                 if (MUX_STATUS(data))
 225                         continue;
 226
 227                 if (MUX_EOFIFO(data))
 228                         break;
 229
 230                 if (tty->flip.count >= TTY_FLIPBUF_SIZE)
 231                         continue;
 232
 233                 *tty->flip.char_buf_ptr = data & 0xffu;
 234                 *tty->flip.flag_buf_ptr = TTY_NORMAL;
 235                 port->icount.rx++;
 236
 237                 if (MUX_BREAK(data)) {
 238                         port->icount.brk++;
 239                         if(uart_handle_break(port))
 240                                 continue;
 241                 }
 242
 243                 if (uart_handle_sysrq_char(port, data & 0xffu, NULL))
 244                         continue;
 245
 246                 tty->flip.flag_buf_ptr++;
 247                 tty->flip.char_buf_ptr++;
 248                 tty->flip.count++;
 249         }
 250
 251         if (start_count != port->icount.rx) {
 252                 tty_flip_buffer_push(tty);
 253         }
 254 }
 255
 256 /**
 257  * mux_startup - Initialize the port.
 258  * @port: Ptr to the uart_port.
 259  *
 260  * Grab any resources needed for this port and start the
 261  * mux timer.
 262  */
 263 static int mux_startup(struct uart_port *port)
 264 {
 265         mod_timer(&mux_timer, jiffies + MUX_POLL_DELAY);
 266         return 0;
 267 }
 268
 269 /**
 270  * mux_shutdown - Disable the port.
 271  * @port: Ptr to the uart_port.
 272  *
 273  * Release any resources needed for the port.
 274  */
 275 static void mux_shutdown(struct uart_port *port)
 276 {
 277 }
 278
 279 /**
 280  * mux_set_termios - Chane port parameters.
 281  * @port: Ptr to the uart_port.
 282  * @termios: new termios settings.
 283  * @old: old termios settings.
 284  *
 285  * The Serial Mux does not support this function.
 286  */
 287 static void
 288 mux_set_termios(struct uart_port *port, struct termios *termios,
 289                 struct termios *old)
 290 {
 291 }
 292
 293 /**
 294  * mux_type - Describe the port.
 295  * @port: Ptr to the uart_port.
 296  *
 297  * Return a pointer to a string constant describing the
 298  * specified port.
 299  */
 300 static const char *mux_type(struct uart_port *port)
 301 {
 302         return "Mux";
 303 }
 304
 305 /**
 306  * mux_release_port - Release memory and IO regions.
 307  * @port: Ptr to the uart_port.
 308  *
 309  * Release any memory and IO region resources currently in use by
 310  * the port.
 311  */
 312 static void mux_release_port(struct uart_port *port)
 313 {
 314 }
 315
 316 /**
 317  * mux_request_port - Request memory and IO regions.
 318  * @port: Ptr to the uart_port.
 319  *
 320  * Request any memory and IO region resources required by the port.
 321  * If any fail, no resources should be registered when this function
 322  * returns, and it should return -EBUSY on failure.
 323  */
 324 static int mux_request_port(struct uart_port *port)
 325 {
 326         return 0;
 327 }
 328
 329 /**
 330  * mux_config_port - Perform port autoconfiguration.
 331  * @port: Ptr to the uart_port.
 332  * @type: Bitmask of required configurations.
 333  *
 334  * Perform any autoconfiguration steps for the port.  This functino is
 335  * called if the UPF_BOOT_AUTOCONF flag is specified for the port.
 336  * [Note: This is required for now because of a bug in the Serial core.
 337  *  rmk has already submitted a patch to linus, should be available for
 338  *  2.5.47.]
 339  */
 340 static void mux_config_port(struct uart_port *port, int type)
 341 {
 342         port->type = PORT_MUX;
 343 }
 344
 345 /**
 346  * mux_verify_port - Verify the port information.
 347  * @port: Ptr to the uart_port.
 348  * @ser: Ptr to the serial information.
 349  *
 350  * Verify the new serial port information contained within serinfo is
 351  * suitable for this port type.
 352  */
 353 static int mux_verify_port(struct uart_port *port, struct serial_struct *ser)
 354 {
 355         if(port->membase == NULL)
 356                 return -EINVAL;
 357
 358         return 0;
 359 }
 360
 361 /**
 362  * mux_drv_poll - Mux poll function.
 363  * @unused: Unused variable
 364  *
 365  * This function periodically polls the Serial MUX to check for new data.
 366  */
 367 static void mux_poll(unsigned long unused)
 368 {
 369         int i;
 370
 371         for(i = 0; i < port_cnt; ++i) {
 372                 if(!mux_ports[i].info)
 373                         continue;
 374
 375                 mux_read(&mux_ports[i]);
 376                 mux_write(&mux_ports[i]);
 377         }
 378
 379         mod_timer(&mux_timer, jiffies + MUX_POLL_DELAY);
 380 }
 381
 382
 383 #ifdef CONFIG_SERIAL_MUX_CONSOLE
 384 static void mux_console_write(struct console *co, const char *s, unsigned count)
 385 {
 386         while(count--)
 387                 pdc_iodc_putc(*s++);
 388 }
 389
 390 static int mux_console_setup(struct console *co, char *options)
 391 {
 392         return 0;
 393 }
 394
 395 struct tty_driver *mux_console_device(struct console *co, int *index)
 396 {
 397         *index = co->index;
 398         return mux_driver.tty_driver;
 399 }
 400
 401 static struct console mux_console = {
 402         .name =         "ttyB",
 403         .write =        mux_console_write,
 404         .device =       mux_console_device,
 405         .setup =        mux_console_setup,
 406         .flags =        CON_ENABLED | CON_PRINTBUFFER,
 407         .index =        0,
 408 };
 409
 410 #define MUX_CONSOLE     &mux_console
 411 #else
 412 #define MUX_CONSOLE     NULL
 413 #endif
 414
 415 static struct uart_ops mux_pops = {
 416         .tx_empty =             mux_tx_empty,
 417         .set_mctrl =            mux_set_mctrl,
 418         .get_mctrl =            mux_get_mctrl,
 419         .stop_tx =              mux_stop_tx,
 420         .start_tx =             mux_start_tx,
 421         .stop_rx =              mux_stop_rx,
 422         .enable_ms =            mux_enable_ms,
 423         .break_ctl =            mux_break_ctl,
 424         .startup =              mux_startup,
 425         .shutdown =             mux_shutdown,
 426         .set_termios =          mux_set_termios,
 427         .type =                 mux_type,
 428         .release_port =         mux_release_port,
 429         .request_port =         mux_request_port,
 430         .config_port =          mux_config_port,
 431         .verify_port =          mux_verify_port,
 432 };
 433
 434 /**
 435  * mux_probe - Determine if the Serial Mux should claim this device.
 436  * @dev: The parisc device.
 437  *
 438  * Deterimine if the Serial Mux should claim this chip (return 0)
 439  * or not (return 1).
 440  */
 441 static int __init mux_probe(struct parisc_device *dev)
 442 {
 443         int i, status, ports;
 444         u8 iodc_data[32];
 445         unsigned long bytecnt;
 446         struct uart_port *port;
 447
 448         status = pdc_iodc_read(&bytecnt, dev->hpa.start, 0, iodc_data, 32);
 449         if(status != PDC_OK) {
 450                 printk(KERN_ERR "Serial mux: Unable to read IODC.\n");
 451                 return 1;
 452         }
 453
 454         ports = GET_MUX_PORTS(iodc_data);
 455         printk(KERN_INFO "Serial mux driver (%d ports) Revision: 0.3\n", ports);
 456
 457         if(!port_cnt) {
 458                 mux_driver.cons = MUX_CONSOLE;
 459
 460                 status = uart_register_driver(&mux_driver);
 461                 if(status) {
 462                         printk(KERN_ERR "Serial mux: Unable to register driver.\n");
 463                         return 1;
 464                 }
 465
 466                 init_timer(&mux_timer);
 467                 mux_timer.function = mux_poll;
 468         }
 469
 470         for(i = 0; i < ports; ++i, ++port_cnt) {
 471                 port = &mux_ports[port_cnt];
 472                 port->iobase    = 0;
 473                 port->mapbase   = dev->hpa.start + MUX_OFFSET +
 474                                                 (i * MUX_LINE_OFFSET);
 475                 port->membase   = ioremap(port->mapbase, MUX_LINE_OFFSET);
 476                 port->iotype    = SERIAL_IO_MEM;
 477                 port->type      = PORT_MUX;
 478                 port->irq       = NO_IRQ;
 479                 port->uartclk   = 0;
 480                 port->fifosize  = MUX_FIFO_SIZE;
 481                 port->ops       = &mux_pops;
 482                 port->flags     = UPF_BOOT_AUTOCONF;
 483                 port->line      = port_cnt;
 484                 spin_lock_init(&port->lock);
 485                 status = uart_add_one_port(&mux_driver, port);
 486                 BUG_ON(status);
 487         }
 488
 489 #ifdef CONFIG_SERIAL_MUX_CONSOLE
 490         register_console(&mux_console);
 491 #endif
 492         return 0;
 493 }
 494
 495 static struct parisc_device_id mux_tbl[] = {
 496         { HPHW_A_DIRECT, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x0000D },
 497         { 0, }
 498 };
 499
 500 MODULE_DEVICE_TABLE(parisc, mux_tbl);
 501
 502 static struct parisc_driver serial_mux_driver = {
 503         .name =         "serial_mux",
 504         .id_table =     mux_tbl,
 505         .probe =        mux_probe,
 506 };
 507
 508 /**
 509  * mux_init - Serial MUX initalization procedure.
 510  *
 511  * Register the Serial MUX driver.
 512  */
 513 static int __init mux_init(void)
 514 {
 515         return register_parisc_driver(&serial_mux_driver);
 516 }
 517
 518 /**
 519  * mux_exit - Serial MUX cleanup procedure.
 520  *
 521  * Unregister the Serial MUX driver from the tty layer.
 522  */
 523 static void __exit mux_exit(void)
 524 {
 525         int i;
 526
 527         for (i = 0; i < port_cnt; i++) {
 528                 uart_remove_one_port(&mux_driver, &mux_ports[i]);
 529         }
 530
 531         uart_unregister_driver(&mux_driver);
 532 }
 533
 534 module_init(mux_init);
 535 module_exit(mux_exit);
 536
 537 MODULE_AUTHOR("Ryan Bradetich");
 538 MODULE_DESCRIPTION("Serial MUX driver");
 539 MODULE_LICENSE("GPL");
 540 MODULE_ALIAS_CHARDEV_MAJOR(MUX_MAJOR);