linux/arch/ia64/hp/sim/simserial.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Simulated Serial Driver (fake serial)
   4 *
   5 * This driver is mostly used for bringup purposes and will go away.
   6 * It has a strong dependency on the system console. All outputs
   7 * are rerouted to the same facility as the one used by printk which, in our
   8 * case means sys_sim.c console (goes via the simulator).
   9 *
  10 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
  11 *      Stephane Eranian <eranian@hpl.hp.com>
  12 *      David Mosberger-Tang <davidm@hpl.hp.com>
  13 */
  14
  15#include <linux/init.h>
  16#include <linux/errno.h>
  17#include <linux/sched.h>
  18#include <linux/sched/debug.h>
  19#include <linux/tty.h>
  20#include <linux/tty_flip.h>
  21#include <linux/major.h>
  22#include <linux/fcntl.h>
  23#include <linux/mm.h>
  24#include <linux/seq_file.h>
  25#include <linux/slab.h>
  26#include <linux/capability.h>
  27#include <linux/circ_buf.h>
  28#include <linux/console.h>
  29#include <linux/irq.h>
  30#include <linux/module.h>
  31#include <linux/serial.h>
  32#include <linux/sysrq.h>
  33#include <linux/uaccess.h>
  34
  35#include <asm/hpsim.h>
  36
  37#include "hpsim_ssc.h"
  38
  39#undef SIMSERIAL_DEBUG  /* define this to get some debug information */
  40
  41#define KEYBOARD_INTR   3       /* must match with simulator! */
  42
  43#define NR_PORTS        1       /* only one port for now */
  44
  45struct serial_state {
  46        struct tty_port port;
  47        struct circ_buf xmit;
  48        int irq;
  49        int x_char;
  50};
  51
  52static struct serial_state rs_table[NR_PORTS];
  53
  54struct tty_driver *hp_simserial_driver;
  55
  56static struct console *console;
  57
  58static void receive_chars(struct tty_port *port)
  59{
  60        unsigned char ch;
  61        static unsigned char seen_esc = 0;
  62
  63        while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
  64                if (ch == 27 && seen_esc == 0) {
  65                        seen_esc = 1;
  66                        continue;
  67                } else if (seen_esc == 1 && ch == 'O') {
  68                        seen_esc = 2;
  69                        continue;
  70                } else if (seen_esc == 2) {
  71                        if (ch == 'P') /* F1 */
  72                                show_state();
  73#ifdef CONFIG_MAGIC_SYSRQ
  74                        if (ch == 'S') { /* F4 */
  75                                do {
  76                                        ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
  77                                } while (!ch);
  78                                handle_sysrq(ch);
  79                        }
  80#endif
  81                        seen_esc = 0;
  82                        continue;
  83                }
  84                seen_esc = 0;
  85
  86                if (tty_insert_flip_char(port, ch, TTY_NORMAL) == 0)
  87                        break;
  88        }
  89        tty_flip_buffer_push(port);
  90}
  91
  92/*
  93 * This is the serial driver's interrupt routine for a single port
  94 */
  95static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
  96{
  97        struct serial_state *info = dev_id;
  98
  99        receive_chars(&info->port);
 100
 101        return IRQ_HANDLED;
 102}
 103
 104/*
 105 * -------------------------------------------------------------------
 106 * Here ends the serial interrupt routines.
 107 * -------------------------------------------------------------------
 108 */
 109
 110static int rs_put_char(struct tty_struct *tty, unsigned char ch)
 111{
 112        struct serial_state *info = tty->driver_data;
 113        unsigned long flags;
 114
 115        if (!info->xmit.buf)
 116                return 0;
 117
 118        local_irq_save(flags);
 119        if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
 120                local_irq_restore(flags);
 121                return 0;
 122        }
 123        info->xmit.buf[info->xmit.head] = ch;
 124        info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
 125        local_irq_restore(flags);
 126        return 1;
 127}
 128
 129static void transmit_chars(struct tty_struct *tty, struct serial_state *info,
 130                int *intr_done)
 131{
 132        int count;
 133        unsigned long flags;
 134
 135        local_irq_save(flags);
 136
 137        if (info->x_char) {
 138                char c = info->x_char;
 139
 140                console->write(console, &c, 1);
 141
 142                info->x_char = 0;
 143
 144                goto out;
 145        }
 146
 147        if (info->xmit.head == info->xmit.tail || tty->stopped) {
 148#ifdef SIMSERIAL_DEBUG
 149                printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
 150                       info->xmit.head, info->xmit.tail, tty->stopped);
 151#endif
 152                goto out;
 153        }
 154        /*
 155         * We removed the loop and try to do it in to chunks. We need
 156         * 2 operations maximum because it's a ring buffer.
 157         *
 158         * First from current to tail if possible.
 159         * Then from the beginning of the buffer until necessary
 160         */
 161
 162        count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
 163                    SERIAL_XMIT_SIZE - info->xmit.tail);
 164        console->write(console, info->xmit.buf+info->xmit.tail, count);
 165
 166        info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);
 167
 168        /*
 169         * We have more at the beginning of the buffer
 170         */
 171        count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 172        if (count) {
 173                console->write(console, info->xmit.buf, count);
 174                info->xmit.tail += count;
 175        }
 176out:
 177        local_irq_restore(flags);
 178}
 179
 180static void rs_flush_chars(struct tty_struct *tty)
 181{
 182        struct serial_state *info = tty->driver_data;
 183
 184        if (info->xmit.head == info->xmit.tail || tty->stopped ||
 185                        !info->xmit.buf)
 186                return;
 187
 188        transmit_chars(tty, info, NULL);
 189}
 190
 191static int rs_write(struct tty_struct * tty,
 192                    const unsigned char *buf, int count)
 193{
 194        struct serial_state *info = tty->driver_data;
 195        int     c, ret = 0;
 196        unsigned long flags;
 197
 198        if (!info->xmit.buf)
 199                return 0;
 200
 201        local_irq_save(flags);
 202        while (1) {
 203                c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 204                if (count < c)
 205                        c = count;
 206                if (c <= 0) {
 207                        break;
 208                }
 209                memcpy(info->xmit.buf + info->xmit.head, buf, c);
 210                info->xmit.head = ((info->xmit.head + c) &
 211                                   (SERIAL_XMIT_SIZE-1));
 212                buf += c;
 213                count -= c;
 214                ret += c;
 215        }
 216        local_irq_restore(flags);
 217        /*
 218         * Hey, we transmit directly from here in our case
 219         */
 220        if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
 221                        !tty->stopped)
 222                transmit_chars(tty, info, NULL);
 223
 224        return ret;
 225}
 226
 227static int rs_write_room(struct tty_struct *tty)
 228{
 229        struct serial_state *info = tty->driver_data;
 230
 231        return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 232}
 233
 234static int rs_chars_in_buffer(struct tty_struct *tty)
 235{
 236        struct serial_state *info = tty->driver_data;
 237
 238        return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 239}
 240
 241static void rs_flush_buffer(struct tty_struct *tty)
 242{
 243        struct serial_state *info = tty->driver_data;
 244        unsigned long flags;
 245
 246        local_irq_save(flags);
 247        info->xmit.head = info->xmit.tail = 0;
 248        local_irq_restore(flags);
 249
 250        tty_wakeup(tty);
 251}
 252
 253/*
 254 * This function is used to send a high-priority XON/XOFF character to
 255 * the device
 256 */
 257static void rs_send_xchar(struct tty_struct *tty, char ch)
 258{
 259        struct serial_state *info = tty->driver_data;
 260
 261        info->x_char = ch;
 262        if (ch) {
 263                /*
 264                 * I guess we could call console->write() directly but
 265                 * let's do that for now.
 266                 */
 267                transmit_chars(tty, info, NULL);
 268        }
 269}
 270
 271/*
 272 * ------------------------------------------------------------
 273 * rs_throttle()
 274 *
 275 * This routine is called by the upper-layer tty layer to signal that
 276 * incoming characters should be throttled.
 277 * ------------------------------------------------------------
 278 */
 279static void rs_throttle(struct tty_struct * tty)
 280{
 281        if (I_IXOFF(tty))
 282                rs_send_xchar(tty, STOP_CHAR(tty));
 283
 284        printk(KERN_INFO "simrs_throttle called\n");
 285}
 286
 287static void rs_unthrottle(struct tty_struct * tty)
 288{
 289        struct serial_state *info = tty->driver_data;
 290
 291        if (I_IXOFF(tty)) {
 292                if (info->x_char)
 293                        info->x_char = 0;
 294                else
 295                        rs_send_xchar(tty, START_CHAR(tty));
 296        }
 297        printk(KERN_INFO "simrs_unthrottle called\n");
 298}
 299
 300static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 301{
 302        if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
 303            (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
 304            (cmd != TIOCMIWAIT)) {
 305                if (tty_io_error(tty))
 306                    return -EIO;
 307        }
 308
 309        switch (cmd) {
 310        case TIOCGSERIAL:
 311        case TIOCSSERIAL:
 312        case TIOCSERGSTRUCT:
 313        case TIOCMIWAIT:
 314                return 0;
 315        case TIOCSERCONFIG:
 316        case TIOCSERGETLSR: /* Get line status register */
 317                return -EINVAL;
 318        case TIOCSERGWILD:
 319        case TIOCSERSWILD:
 320                /* "setserial -W" is called in Debian boot */
 321                printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
 322                return 0;
 323        }
 324        return -ENOIOCTLCMD;
 325}
 326
 327#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
 328
 329/*
 330 * This routine will shutdown a serial port; interrupts are disabled, and
 331 * DTR is dropped if the hangup on close termio flag is on.
 332 */
 333static void shutdown(struct tty_port *port)
 334{
 335        struct serial_state *info = container_of(port, struct serial_state,
 336                        port);
 337        unsigned long flags;
 338
 339        local_irq_save(flags);
 340        if (info->irq)
 341                free_irq(info->irq, info);
 342
 343        if (info->xmit.buf) {
 344                free_page((unsigned long) info->xmit.buf);
 345                info->xmit.buf = NULL;
 346        }
 347        local_irq_restore(flags);
 348}
 349
 350static void rs_close(struct tty_struct *tty, struct file * filp)
 351{
 352        struct serial_state *info = tty->driver_data;
 353
 354        tty_port_close(&info->port, tty, filp);
 355}
 356
 357static void rs_hangup(struct tty_struct *tty)
 358{
 359        struct serial_state *info = tty->driver_data;
 360
 361        rs_flush_buffer(tty);
 362        tty_port_hangup(&info->port);
 363}
 364
 365static int activate(struct tty_port *port, struct tty_struct *tty)
 366{
 367        struct serial_state *state = container_of(port, struct serial_state,
 368                        port);
 369        unsigned long flags, page;
 370        int retval = 0;
 371
 372        page = get_zeroed_page(GFP_KERNEL);
 373        if (!page)
 374                return -ENOMEM;
 375
 376        local_irq_save(flags);
 377
 378        if (state->xmit.buf)
 379                free_page(page);
 380        else
 381                state->xmit.buf = (unsigned char *) page;
 382
 383        if (state->irq) {
 384                retval = request_irq(state->irq, rs_interrupt_single, 0,
 385                                "simserial", state);
 386                if (retval)
 387                        goto errout;
 388        }
 389
 390        state->xmit.head = state->xmit.tail = 0;
 391errout:
 392        local_irq_restore(flags);
 393        return retval;
 394}
 395
 396
 397/*
 398 * This routine is called whenever a serial port is opened.  It
 399 * enables interrupts for a serial port, linking in its async structure into
 400 * the IRQ chain.   It also performs the serial-specific
 401 * initialization for the tty structure.
 402 */
 403static int rs_open(struct tty_struct *tty, struct file * filp)
 404{
 405        struct serial_state *info = rs_table + tty->index;
 406        struct tty_port *port = &info->port;
 407
 408        tty->driver_data = info;
 409        port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 410
 411        /*
 412         * figure out which console to use (should be one already)
 413         */
 414        console = console_drivers;
 415        while (console) {
 416                if ((console->flags & CON_ENABLED) && console->write) break;
 417                console = console->next;
 418        }
 419
 420        return tty_port_open(port, tty, filp);
 421}
 422
 423/*
 424 * /proc fs routines....
 425 */
 426
 427static int rs_proc_show(struct seq_file *m, void *v)
 428{
 429        int i;
 430
 431        seq_printf(m, "simserinfo:1.0\n");
 432        for (i = 0; i < NR_PORTS; i++)
 433                seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
 434                       i, rs_table[i].irq);
 435        return 0;
 436}
 437
 438static const struct tty_operations hp_ops = {
 439        .open = rs_open,
 440        .close = rs_close,
 441        .write = rs_write,
 442        .put_char = rs_put_char,
 443        .flush_chars = rs_flush_chars,
 444        .write_room = rs_write_room,
 445        .chars_in_buffer = rs_chars_in_buffer,
 446        .flush_buffer = rs_flush_buffer,
 447        .ioctl = rs_ioctl,
 448        .throttle = rs_throttle,
 449        .unthrottle = rs_unthrottle,
 450        .send_xchar = rs_send_xchar,
 451        .hangup = rs_hangup,
 452        .proc_show = rs_proc_show,
 453};
 454
 455static const struct tty_port_operations hp_port_ops = {
 456        .activate = activate,
 457        .shutdown = shutdown,
 458};
 459
 460static int __init simrs_init(void)
 461{
 462        struct serial_state *state;
 463        int retval;
 464
 465        if (!ia64_platform_is("hpsim"))
 466                return -ENODEV;
 467
 468        hp_simserial_driver = alloc_tty_driver(NR_PORTS);
 469        if (!hp_simserial_driver)
 470                return -ENOMEM;
 471
 472        printk(KERN_INFO "SimSerial driver with no serial options enabled\n");
 473
 474        /* Initialize the tty_driver structure */
 475
 476        hp_simserial_driver->driver_name = "simserial";
 477        hp_simserial_driver->name = "ttyS";
 478        hp_simserial_driver->major = TTY_MAJOR;
 479        hp_simserial_driver->minor_start = 64;
 480        hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
 481        hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
 482        hp_simserial_driver->init_termios = tty_std_termios;
 483        hp_simserial_driver->init_termios.c_cflag =
 484                B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 485        hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
 486        tty_set_operations(hp_simserial_driver, &hp_ops);
 487
 488        state = rs_table;
 489        tty_port_init(&state->port);
 490        state->port.ops = &hp_port_ops;
 491        state->port.close_delay = 0; /* XXX really 0? */
 492
 493        retval = hpsim_get_irq(KEYBOARD_INTR);
 494        if (retval < 0) {
 495                printk(KERN_ERR "%s: out of interrupt vectors!\n",
 496                                __func__);
 497                goto err_free_tty;
 498        }
 499
 500        state->irq = retval;
 501
 502        /* the port is imaginary */
 503        printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);
 504
 505        tty_port_link_device(&state->port, hp_simserial_driver, 0);
 506        retval = tty_register_driver(hp_simserial_driver);
 507        if (retval) {
 508                printk(KERN_ERR "Couldn't register simserial driver\n");
 509                goto err_free_tty;
 510        }
 511
 512        return 0;
 513err_free_tty:
 514        put_tty_driver(hp_simserial_driver);
 515        tty_port_destroy(&state->port);
 516        return retval;
 517}
 518
 519#ifndef MODULE
 520__initcall(simrs_init);
 521#endif
 522