arch/ia64/hp/sim/simserial.c

   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
  45 struct serial_state {
  46         struct tty_port port;
  47         struct circ_buf xmit;
  48         int irq;
  49         int x_char;
  50 };
  51
  52 static struct serial_state rs_table[NR_PORTS];
  53
  54 struct tty_driver *hp_simserial_driver;
  55
  56 static struct console *console;
  57
  58 static 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  */
  95 static 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
 110 static 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
 129 static 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         }
 176 out:
 177         local_irq_restore(flags);
 178 }
 179
 180 static 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
 191 static 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
 227 static 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
 234 static 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
 241 static 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  */
 257 static 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  */
 279 static 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
 287 static 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
 300 static int rs_setserial(struct tty_struct *tty, struct serial_struct *ss)
 301 {
 302         return 0;
 303 }
 304
 305 static int rs_getserial(struct tty_struct *tty, struct serial_struct *ss)
 306 {
 307         return 0;
 308 }
 309
 310 static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 311 {
 312         if ((cmd != TIOCSERCONFIG) && (cmd != TIOCMIWAIT)) {
 313                 if (tty_io_error(tty))
 314                     return -EIO;
 315         }
 316
 317         switch (cmd) {
 318         case TIOCMIWAIT:
 319                 return 0;
 320         case TIOCSERCONFIG:
 321         case TIOCSERGETLSR: /* Get line status register */
 322                 return -EINVAL;
 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  */
 333 static 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
 350 static 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
 357 static 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
 365 static 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;
 391 errout:
 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  */
 403 static 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
 427 static 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
 438 static 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         .set_serial = rs_setserial,
 452         .get_serial = rs_getserial,
 453         .hangup = rs_hangup,
 454         .proc_show = rs_proc_show,
 455 };
 456
 457 static const struct tty_port_operations hp_port_ops = {
 458         .activate = activate,
 459         .shutdown = shutdown,
 460 };
 461
 462 static int __init simrs_init(void)
 463 {
 464         struct serial_state *state;
 465         int retval;
 466
 467         if (!ia64_platform_is("hpsim"))
 468                 return -ENODEV;
 469
 470         hp_simserial_driver = alloc_tty_driver(NR_PORTS);
 471         if (!hp_simserial_driver)
 472                 return -ENOMEM;
 473
 474         printk(KERN_INFO "SimSerial driver with no serial options enabled\n");
 475
 476         /* Initialize the tty_driver structure */
 477
 478         hp_simserial_driver->driver_name = "simserial";
 479         hp_simserial_driver->name = "ttyS";
 480         hp_simserial_driver->major = TTY_MAJOR;
 481         hp_simserial_driver->minor_start = 64;
 482         hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
 483         hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
 484         hp_simserial_driver->init_termios = tty_std_termios;
 485         hp_simserial_driver->init_termios.c_cflag =
 486                 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 487         hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
 488         tty_set_operations(hp_simserial_driver, &hp_ops);
 489
 490         state = rs_table;
 491         tty_port_init(&state->port);
 492         state->port.ops = &hp_port_ops;
 493         state->port.close_delay = 0; /* XXX really 0? */
 494
 495         retval = hpsim_get_irq(KEYBOARD_INTR);
 496         if (retval < 0) {
 497                 printk(KERN_ERR "%s: out of interrupt vectors!\n",
 498                                 __func__);
 499                 goto err_free_tty;
 500         }
 501
 502         state->irq = retval;
 503
 504         /* the port is imaginary */
 505         printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);
 506
 507         tty_port_link_device(&state->port, hp_simserial_driver, 0);
 508         retval = tty_register_driver(hp_simserial_driver);
 509         if (retval) {
 510                 printk(KERN_ERR "Couldn't register simserial driver\n");
 511                 goto err_free_tty;
 512         }
 513
 514         return 0;
 515 err_free_tty:
 516         put_tty_driver(hp_simserial_driver);
 517         tty_port_destroy(&state->port);
 518         return retval;
 519 }
 520
 521 #ifndef MODULE
 522 __initcall(simrs_init);
 523 #endif