drivers/tty/serial/sunhv.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* sunhv.c: Serial driver for SUN4V hypervisor console.
   3  *
   4  * Copyright (C) 2006, 2007 David S. Miller (davem@davemloft.net)
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/errno.h>
   9 #include <linux/tty.h>
  10 #include <linux/tty_flip.h>
  11 #include <linux/major.h>
  12 #include <linux/circ_buf.h>
  13 #include <linux/serial.h>
  14 #include <linux/sysrq.h>
  15 #include <linux/console.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/slab.h>
  18 #include <linux/delay.h>
  19 #include <linux/init.h>
  20 #include <linux/of_device.h>
  21
  22 #include <asm/hypervisor.h>
  23 #include <asm/spitfire.h>
  24 #include <asm/prom.h>
  25 #include <asm/irq.h>
  26 #include <asm/setup.h>
  27
  28 #include <linux/serial_core.h>
  29 #include <linux/sunserialcore.h>
  30
  31 #define CON_BREAK       ((long)-1)
  32 #define CON_HUP         ((long)-2)
  33
  34 #define IGNORE_BREAK    0x1
  35 #define IGNORE_ALL      0x2
  36
  37 static char *con_write_page;
  38 static char *con_read_page;
  39
  40 static int hung_up = 0;
  41
  42 static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
  43 {
  44         while (!uart_circ_empty(xmit)) {
  45                 long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
  46
  47                 if (status != HV_EOK)
  48                         break;
  49
  50                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
  51                 port->icount.tx++;
  52         }
  53 }
  54
  55 static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
  56 {
  57         while (!uart_circ_empty(xmit)) {
  58                 unsigned long ra = __pa(xmit->buf + xmit->tail);
  59                 unsigned long len, status, sent;
  60
  61                 len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
  62                                       UART_XMIT_SIZE);
  63                 status = sun4v_con_write(ra, len, &sent);
  64                 if (status != HV_EOK)
  65                         break;
  66                 xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
  67                 port->icount.tx += sent;
  68         }
  69 }
  70
  71 static int receive_chars_getchar(struct uart_port *port)
  72 {
  73         int saw_console_brk = 0;
  74         int limit = 10000;
  75
  76         while (limit-- > 0) {
  77                 long status;
  78                 long c = sun4v_con_getchar(&status);
  79
  80                 if (status == HV_EWOULDBLOCK)
  81                         break;
  82
  83                 if (c == CON_BREAK) {
  84                         if (uart_handle_break(port))
  85                                 continue;
  86                         saw_console_brk = 1;
  87                         c = 0;
  88                 }
  89
  90                 if (c == CON_HUP) {
  91                         hung_up = 1;
  92                         uart_handle_dcd_change(port, 0);
  93                 } else if (hung_up) {
  94                         hung_up = 0;
  95                         uart_handle_dcd_change(port, 1);
  96                 }
  97
  98                 if (port->state == NULL) {
  99                         uart_handle_sysrq_char(port, c);
 100                         continue;
 101                 }
 102
 103                 port->icount.rx++;
 104
 105                 if (uart_handle_sysrq_char(port, c))
 106                         continue;
 107
 108                 tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
 109         }
 110
 111         return saw_console_brk;
 112 }
 113
 114 static int receive_chars_read(struct uart_port *port)
 115 {
 116         static int saw_console_brk;
 117         int limit = 10000;
 118
 119         while (limit-- > 0) {
 120                 unsigned long ra = __pa(con_read_page);
 121                 unsigned long bytes_read, i;
 122                 long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
 123
 124                 if (stat != HV_EOK) {
 125                         bytes_read = 0;
 126
 127                         if (stat == CON_BREAK) {
 128                                 if (saw_console_brk)
 129                                         sun_do_break();
 130
 131                                 if (uart_handle_break(port))
 132                                         continue;
 133                                 saw_console_brk = 1;
 134                                 *con_read_page = 0;
 135                                 bytes_read = 1;
 136                         } else if (stat == CON_HUP) {
 137                                 hung_up = 1;
 138                                 uart_handle_dcd_change(port, 0);
 139                                 continue;
 140                         } else {
 141                                 /* HV_EWOULDBLOCK, etc.  */
 142                                 break;
 143                         }
 144                 }
 145
 146                 if (hung_up) {
 147                         hung_up = 0;
 148                         uart_handle_dcd_change(port, 1);
 149                 }
 150
 151                 if (port->sysrq != 0 &&  *con_read_page) {
 152                         for (i = 0; i < bytes_read; i++)
 153                                 uart_handle_sysrq_char(port, con_read_page[i]);
 154                         saw_console_brk = 0;
 155                 }
 156
 157                 if (port->state == NULL)
 158                         continue;
 159
 160                 port->icount.rx += bytes_read;
 161
 162                 tty_insert_flip_string(&port->state->port, con_read_page,
 163                                 bytes_read);
 164         }
 165
 166         return saw_console_brk;
 167 }
 168
 169 struct sunhv_ops {
 170         void (*transmit_chars)(struct uart_port *port, struct circ_buf *xmit);
 171         int (*receive_chars)(struct uart_port *port);
 172 };
 173
 174 static const struct sunhv_ops bychar_ops = {
 175         .transmit_chars = transmit_chars_putchar,
 176         .receive_chars = receive_chars_getchar,
 177 };
 178
 179 static const struct sunhv_ops bywrite_ops = {
 180         .transmit_chars = transmit_chars_write,
 181         .receive_chars = receive_chars_read,
 182 };
 183
 184 static const struct sunhv_ops *sunhv_ops = &bychar_ops;
 185
 186 static struct tty_port *receive_chars(struct uart_port *port)
 187 {
 188         struct tty_port *tport = NULL;
 189
 190         if (port->state != NULL)                /* Unopened serial console */
 191                 tport = &port->state->port;
 192
 193         if (sunhv_ops->receive_chars(port))
 194                 sun_do_break();
 195
 196         return tport;
 197 }
 198
 199 static void transmit_chars(struct uart_port *port)
 200 {
 201         struct circ_buf *xmit;
 202
 203         if (!port->state)
 204                 return;
 205
 206         xmit = &port->state->xmit;
 207         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 208                 return;
 209
 210         sunhv_ops->transmit_chars(port, xmit);
 211
 212         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 213                 uart_write_wakeup(port);
 214 }
 215
 216 static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
 217 {
 218         struct uart_port *port = dev_id;
 219         struct tty_port *tport;
 220         unsigned long flags;
 221
 222         spin_lock_irqsave(&port->lock, flags);
 223         tport = receive_chars(port);
 224         transmit_chars(port);
 225         spin_unlock_irqrestore(&port->lock, flags);
 226
 227         if (tport)
 228                 tty_flip_buffer_push(tport);
 229
 230         return IRQ_HANDLED;
 231 }
 232
 233 /* port->lock is not held.  */
 234 static unsigned int sunhv_tx_empty(struct uart_port *port)
 235 {
 236         /* Transmitter is always empty for us.  If the circ buffer
 237          * is non-empty or there is an x_char pending, our caller
 238          * will do the right thing and ignore what we return here.
 239          */
 240         return TIOCSER_TEMT;
 241 }
 242
 243 /* port->lock held by caller.  */
 244 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
 245 {
 246         return;
 247 }
 248
 249 /* port->lock is held by caller and interrupts are disabled.  */
 250 static unsigned int sunhv_get_mctrl(struct uart_port *port)
 251 {
 252         return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
 253 }
 254
 255 /* port->lock held by caller.  */
 256 static void sunhv_stop_tx(struct uart_port *port)
 257 {
 258         return;
 259 }
 260
 261 /* port->lock held by caller.  */
 262 static void sunhv_start_tx(struct uart_port *port)
 263 {
 264         transmit_chars(port);
 265 }
 266
 267 /* port->lock is not held.  */
 268 static void sunhv_send_xchar(struct uart_port *port, char ch)
 269 {
 270         unsigned long flags;
 271         int limit = 10000;
 272
 273         if (ch == __DISABLED_CHAR)
 274                 return;
 275
 276         spin_lock_irqsave(&port->lock, flags);
 277
 278         while (limit-- > 0) {
 279                 long status = sun4v_con_putchar(ch);
 280                 if (status == HV_EOK)
 281                         break;
 282                 udelay(1);
 283         }
 284
 285         spin_unlock_irqrestore(&port->lock, flags);
 286 }
 287
 288 /* port->lock held by caller.  */
 289 static void sunhv_stop_rx(struct uart_port *port)
 290 {
 291 }
 292
 293 /* port->lock is not held.  */
 294 static void sunhv_break_ctl(struct uart_port *port, int break_state)
 295 {
 296         if (break_state) {
 297                 unsigned long flags;
 298                 int limit = 10000;
 299
 300                 spin_lock_irqsave(&port->lock, flags);
 301
 302                 while (limit-- > 0) {
 303                         long status = sun4v_con_putchar(CON_BREAK);
 304                         if (status == HV_EOK)
 305                                 break;
 306                         udelay(1);
 307                 }
 308
 309                 spin_unlock_irqrestore(&port->lock, flags);
 310         }
 311 }
 312
 313 /* port->lock is not held.  */
 314 static int sunhv_startup(struct uart_port *port)
 315 {
 316         return 0;
 317 }
 318
 319 /* port->lock is not held.  */
 320 static void sunhv_shutdown(struct uart_port *port)
 321 {
 322 }
 323
 324 /* port->lock is not held.  */
 325 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
 326                               struct ktermios *old)
 327 {
 328         unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 329         unsigned int quot = uart_get_divisor(port, baud);
 330         unsigned int iflag, cflag;
 331         unsigned long flags;
 332
 333         spin_lock_irqsave(&port->lock, flags);
 334
 335         iflag = termios->c_iflag;
 336         cflag = termios->c_cflag;
 337
 338         port->ignore_status_mask = 0;
 339         if (iflag & IGNBRK)
 340                 port->ignore_status_mask |= IGNORE_BREAK;
 341         if ((cflag & CREAD) == 0)
 342                 port->ignore_status_mask |= IGNORE_ALL;
 343
 344         /* XXX */
 345         uart_update_timeout(port, cflag,
 346                             (port->uartclk / (16 * quot)));
 347
 348         spin_unlock_irqrestore(&port->lock, flags);
 349 }
 350
 351 static const char *sunhv_type(struct uart_port *port)
 352 {
 353         return "SUN4V HCONS";
 354 }
 355
 356 static void sunhv_release_port(struct uart_port *port)
 357 {
 358 }
 359
 360 static int sunhv_request_port(struct uart_port *port)
 361 {
 362         return 0;
 363 }
 364
 365 static void sunhv_config_port(struct uart_port *port, int flags)
 366 {
 367 }
 368
 369 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
 370 {
 371         return -EINVAL;
 372 }
 373
 374 static const struct uart_ops sunhv_pops = {
 375         .tx_empty       = sunhv_tx_empty,
 376         .set_mctrl      = sunhv_set_mctrl,
 377         .get_mctrl      = sunhv_get_mctrl,
 378         .stop_tx        = sunhv_stop_tx,
 379         .start_tx       = sunhv_start_tx,
 380         .send_xchar     = sunhv_send_xchar,
 381         .stop_rx        = sunhv_stop_rx,
 382         .break_ctl      = sunhv_break_ctl,
 383         .startup        = sunhv_startup,
 384         .shutdown       = sunhv_shutdown,
 385         .set_termios    = sunhv_set_termios,
 386         .type           = sunhv_type,
 387         .release_port   = sunhv_release_port,
 388         .request_port   = sunhv_request_port,
 389         .config_port    = sunhv_config_port,
 390         .verify_port    = sunhv_verify_port,
 391 };
 392
 393 static struct uart_driver sunhv_reg = {
 394         .owner                  = THIS_MODULE,
 395         .driver_name            = "sunhv",
 396         .dev_name               = "ttyHV",
 397         .major                  = TTY_MAJOR,
 398 };
 399
 400 static struct uart_port *sunhv_port;
 401
 402 void sunhv_migrate_hvcons_irq(int cpu)
 403 {
 404         /* Migrate hvcons irq to param cpu */
 405         irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
 406 }
 407
 408 /* Copy 's' into the con_write_page, decoding "\n" into
 409  * "\r\n" along the way.  We have to return two lengths
 410  * because the caller needs to know how much to advance
 411  * 's' and also how many bytes to output via con_write_page.
 412  */
 413 static int fill_con_write_page(const char *s, unsigned int n,
 414                                unsigned long *page_bytes)
 415 {
 416         const char *orig_s = s;
 417         char *p = con_write_page;
 418         int left = PAGE_SIZE;
 419
 420         while (n--) {
 421                 if (*s == '\n') {
 422                         if (left < 2)
 423                                 break;
 424                         *p++ = '\r';
 425                         left--;
 426                 } else if (left < 1)
 427                         break;
 428                 *p++ = *s++;
 429                 left--;
 430         }
 431         *page_bytes = p - con_write_page;
 432         return s - orig_s;
 433 }
 434
 435 static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
 436 {
 437         struct uart_port *port = sunhv_port;
 438         unsigned long flags;
 439         int locked = 1;
 440
 441         if (port->sysrq || oops_in_progress)
 442                 locked = spin_trylock_irqsave(&port->lock, flags);
 443         else
 444                 spin_lock_irqsave(&port->lock, flags);
 445
 446         while (n > 0) {
 447                 unsigned long ra = __pa(con_write_page);
 448                 unsigned long page_bytes;
 449                 unsigned int cpy = fill_con_write_page(s, n,
 450                                                        &page_bytes);
 451
 452                 n -= cpy;
 453                 s += cpy;
 454                 while (page_bytes > 0) {
 455                         unsigned long written;
 456                         int limit = 1000000;
 457
 458                         while (limit--) {
 459                                 unsigned long stat;
 460
 461                                 stat = sun4v_con_write(ra, page_bytes,
 462                                                        &written);
 463                                 if (stat == HV_EOK)
 464                                         break;
 465                                 udelay(1);
 466                         }
 467                         if (limit < 0)
 468                                 break;
 469                         page_bytes -= written;
 470                         ra += written;
 471                 }
 472         }
 473
 474         if (locked)
 475                 spin_unlock_irqrestore(&port->lock, flags);
 476 }
 477
 478 static inline void sunhv_console_putchar(struct uart_port *port, char c)
 479 {
 480         int limit = 1000000;
 481
 482         while (limit-- > 0) {
 483                 long status = sun4v_con_putchar(c);
 484                 if (status == HV_EOK)
 485                         break;
 486                 udelay(1);
 487         }
 488 }
 489
 490 static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
 491 {
 492         struct uart_port *port = sunhv_port;
 493         unsigned long flags;
 494         int i, locked = 1;
 495
 496         if (port->sysrq || oops_in_progress)
 497                 locked = spin_trylock_irqsave(&port->lock, flags);
 498         else
 499                 spin_lock_irqsave(&port->lock, flags);
 500
 501         for (i = 0; i < n; i++) {
 502                 if (*s == '\n')
 503                         sunhv_console_putchar(port, '\r');
 504                 sunhv_console_putchar(port, *s++);
 505         }
 506
 507         if (locked)
 508                 spin_unlock_irqrestore(&port->lock, flags);
 509 }
 510
 511 static struct console sunhv_console = {
 512         .name   =       "ttyHV",
 513         .write  =       sunhv_console_write_bychar,
 514         .device =       uart_console_device,
 515         .flags  =       CON_PRINTBUFFER,
 516         .index  =       -1,
 517         .data   =       &sunhv_reg,
 518 };
 519
 520 static int hv_probe(struct platform_device *op)
 521 {
 522         struct uart_port *port;
 523         unsigned long minor;
 524         int err;
 525
 526         if (op->archdata.irqs[0] == 0xffffffff)
 527                 return -ENODEV;
 528
 529         port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
 530         if (unlikely(!port))
 531                 return -ENOMEM;
 532
 533         minor = 1;
 534         if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
 535             minor >= 1) {
 536                 err = -ENOMEM;
 537                 con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
 538                 if (!con_write_page)
 539                         goto out_free_port;
 540
 541                 con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
 542                 if (!con_read_page)
 543                         goto out_free_con_write_page;
 544
 545                 sunhv_console.write = sunhv_console_write_paged;
 546                 sunhv_ops = &bywrite_ops;
 547         }
 548
 549         sunhv_port = port;
 550
 551         port->has_sysrq = 1;
 552         port->line = 0;
 553         port->ops = &sunhv_pops;
 554         port->type = PORT_SUNHV;
 555         port->uartclk = ( 29491200 / 16 ); /* arbitrary */
 556
 557         port->membase = (unsigned char __iomem *) __pa(port);
 558
 559         port->irq = op->archdata.irqs[0];
 560
 561         port->dev = &op->dev;
 562
 563         err = sunserial_register_minors(&sunhv_reg, 1);
 564         if (err)
 565                 goto out_free_con_read_page;
 566
 567         sunserial_console_match(&sunhv_console, op->dev.of_node,
 568                                 &sunhv_reg, port->line, false);
 569
 570         err = uart_add_one_port(&sunhv_reg, port);
 571         if (err)
 572                 goto out_unregister_driver;
 573
 574         err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
 575         if (err)
 576                 goto out_remove_port;
 577
 578         platform_set_drvdata(op, port);
 579
 580         return 0;
 581
 582 out_remove_port:
 583         uart_remove_one_port(&sunhv_reg, port);
 584
 585 out_unregister_driver:
 586         sunserial_unregister_minors(&sunhv_reg, 1);
 587
 588 out_free_con_read_page:
 589         kfree(con_read_page);
 590
 591 out_free_con_write_page:
 592         kfree(con_write_page);
 593
 594 out_free_port:
 595         kfree(port);
 596         sunhv_port = NULL;
 597         return err;
 598 }
 599
 600 static int hv_remove(struct platform_device *dev)
 601 {
 602         struct uart_port *port = platform_get_drvdata(dev);
 603
 604         free_irq(port->irq, port);
 605
 606         uart_remove_one_port(&sunhv_reg, port);
 607
 608         sunserial_unregister_minors(&sunhv_reg, 1);
 609         kfree(con_read_page);
 610         kfree(con_write_page);
 611         kfree(port);
 612         sunhv_port = NULL;
 613
 614         return 0;
 615 }
 616
 617 static const struct of_device_id hv_match[] = {
 618         {
 619                 .name = "console",
 620                 .compatible = "qcn",
 621         },
 622         {
 623                 .name = "console",
 624                 .compatible = "SUNW,sun4v-console",
 625         },
 626         {},
 627 };
 628
 629 static struct platform_driver hv_driver = {
 630         .driver = {
 631                 .name = "hv",
 632                 .of_match_table = hv_match,
 633         },
 634         .probe          = hv_probe,
 635         .remove         = hv_remove,
 636 };
 637
 638 static int __init sunhv_init(void)
 639 {
 640         if (tlb_type != hypervisor)
 641                 return -ENODEV;
 642
 643         return platform_driver_register(&hv_driver);
 644 }
 645 device_initcall(sunhv_init);
 646
 647 #if 0 /* ...def MODULE ; never supported as such */
 648 MODULE_AUTHOR("David S. Miller");
 649 MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
 650 MODULE_VERSION("2.0");
 651 MODULE_LICENSE("GPL");
 652 #endif