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