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   1 /* sunhv.c: Serial driver for SUN4V hypervisor console.
   2  *
   3  * Copyright (C) 2006 David S. Miller (davem@davemloft.net)
   4  */
   5
   6 #include <linux/module.h>
   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
  21 #include <asm/hypervisor.h>
  22 #include <asm/spitfire.h>
  23 #include <asm/vdev.h>
  24 #include <asm/oplib.h>
  25 #include <asm/irq.h>
  26
  27 #if defined(CONFIG_MAGIC_SYSRQ)
  28 #define SUPPORT_SYSRQ
  29 #endif
  30
  31 #include <linux/serial_core.h>
  32
  33 #include "suncore.h"
  34
  35 #define CON_BREAK       ((long)-1)
  36 #define CON_HUP         ((long)-2)
  37
  38 static inline long hypervisor_con_getchar(long *status)
  39 {
  40         register unsigned long func asm("%o5");
  41         register unsigned long arg0 asm("%o0");
  42         register unsigned long arg1 asm("%o1");
  43
  44         func = HV_FAST_CONS_GETCHAR;
  45         arg0 = 0;
  46         arg1 = 0;
  47         __asm__ __volatile__("ta        %6"
  48                              : "=&r" (func), "=&r" (arg0), "=&r" (arg1)
  49                              : "0" (func), "1" (arg0), "2" (arg1),
  50                                "i" (HV_FAST_TRAP));
  51
  52         *status = arg0;
  53
  54         return (long) arg1;
  55 }
  56
  57 static inline long hypervisor_con_putchar(long ch)
  58 {
  59         register unsigned long func asm("%o5");
  60         register unsigned long arg0 asm("%o0");
  61
  62         func = HV_FAST_CONS_PUTCHAR;
  63         arg0 = ch;
  64         __asm__ __volatile__("ta        %4"
  65                              : "=&r" (func), "=&r" (arg0)
  66                              : "0" (func), "1" (arg0), "i" (HV_FAST_TRAP));
  67
  68         return (long) arg0;
  69 }
  70
  71 #define IGNORE_BREAK    0x1
  72 #define IGNORE_ALL      0x2
  73
  74 static int hung_up = 0;
  75
  76 static struct tty_struct *receive_chars(struct uart_port *port, struct pt_regs *regs)
  77 {
  78         struct tty_struct *tty = NULL;
  79         int saw_console_brk = 0;
  80         int limit = 10000;
  81
  82         if (port->info != NULL)         /* Unopened serial console */
  83                 tty = port->info->tty;
  84
  85         while (limit-- > 0) {
  86                 long status;
  87                 long c = hypervisor_con_getchar(&status);
  88                 unsigned char flag;
  89
  90                 if (status == HV_EWOULDBLOCK)
  91                         break;
  92
  93                 if (c == CON_BREAK) {
  94                         if (uart_handle_break(port))
  95                                 continue;
  96                         saw_console_brk = 1;
  97                         c = 0;
  98                 }
  99
 100                 if (c == CON_HUP) {
 101                         hung_up = 1;
 102                         uart_handle_dcd_change(port, 0);
 103                 } else if (hung_up) {
 104                         hung_up = 0;
 105                         uart_handle_dcd_change(port, 1);
 106                 }
 107
 108                 if (tty == NULL) {
 109                         uart_handle_sysrq_char(port, c, regs);
 110                         continue;
 111                 }
 112
 113                 flag = TTY_NORMAL;
 114                 port->icount.rx++;
 115                 if (c == CON_BREAK) {
 116                         port->icount.brk++;
 117                         if (uart_handle_break(port))
 118                                 continue;
 119                         flag = TTY_BREAK;
 120                 }
 121
 122                 if (uart_handle_sysrq_char(port, c, regs))
 123                         continue;
 124
 125                 if ((port->ignore_status_mask & IGNORE_ALL) ||
 126                     ((port->ignore_status_mask & IGNORE_BREAK) &&
 127                      (c == CON_BREAK)))
 128                         continue;
 129
 130                 tty_insert_flip_char(tty, c, flag);
 131         }
 132
 133         if (saw_console_brk)
 134                 sun_do_break();
 135
 136         return tty;
 137 }
 138
 139 static void transmit_chars(struct uart_port *port)
 140 {
 141         struct circ_buf *xmit;
 142
 143         if (!port->info)
 144                 return;
 145
 146         xmit = &port->info->xmit;
 147         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 148                 return;
 149
 150         while (!uart_circ_empty(xmit)) {
 151                 long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
 152
 153                 if (status != HV_EOK)
 154                         break;
 155
 156                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 157                 port->icount.tx++;
 158         }
 159
 160         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 161                 uart_write_wakeup(port);
 162 }
 163
 164 static irqreturn_t sunhv_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 165 {
 166         struct uart_port *port = dev_id;
 167         struct tty_struct *tty;
 168         unsigned long flags;
 169
 170         spin_lock_irqsave(&port->lock, flags);
 171         tty = receive_chars(port, regs);
 172         transmit_chars(port);
 173         spin_unlock_irqrestore(&port->lock, flags);
 174
 175         if (tty)
 176                 tty_flip_buffer_push(tty);
 177
 178         return IRQ_HANDLED;
 179 }
 180
 181 /* port->lock is not held.  */
 182 static unsigned int sunhv_tx_empty(struct uart_port *port)
 183 {
 184         /* Transmitter is always empty for us.  If the circ buffer
 185          * is non-empty or there is an x_char pending, our caller
 186          * will do the right thing and ignore what we return here.
 187          */
 188         return TIOCSER_TEMT;
 189 }
 190
 191 /* port->lock held by caller.  */
 192 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
 193 {
 194         return;
 195 }
 196
 197 /* port->lock is held by caller and interrupts are disabled.  */
 198 static unsigned int sunhv_get_mctrl(struct uart_port *port)
 199 {
 200         return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
 201 }
 202
 203 /* port->lock held by caller.  */
 204 static void sunhv_stop_tx(struct uart_port *port)
 205 {
 206         return;
 207 }
 208
 209 /* port->lock held by caller.  */
 210 static void sunhv_start_tx(struct uart_port *port)
 211 {
 212         struct circ_buf *xmit = &port->info->xmit;
 213
 214         while (!uart_circ_empty(xmit)) {
 215                 long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
 216
 217                 if (status != HV_EOK)
 218                         break;
 219
 220                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 221                 port->icount.tx++;
 222         }
 223 }
 224
 225 /* port->lock is not held.  */
 226 static void sunhv_send_xchar(struct uart_port *port, char ch)
 227 {
 228         unsigned long flags;
 229         int limit = 10000;
 230
 231         spin_lock_irqsave(&port->lock, flags);
 232
 233         while (limit-- > 0) {
 234                 long status = hypervisor_con_putchar(ch);
 235                 if (status == HV_EOK)
 236                         break;
 237         }
 238
 239         spin_unlock_irqrestore(&port->lock, flags);
 240 }
 241
 242 /* port->lock held by caller.  */
 243 static void sunhv_stop_rx(struct uart_port *port)
 244 {
 245 }
 246
 247 /* port->lock held by caller.  */
 248 static void sunhv_enable_ms(struct uart_port *port)
 249 {
 250 }
 251
 252 /* port->lock is not held.  */
 253 static void sunhv_break_ctl(struct uart_port *port, int break_state)
 254 {
 255         if (break_state) {
 256                 unsigned long flags;
 257                 int limit = 1000000;
 258
 259                 spin_lock_irqsave(&port->lock, flags);
 260
 261                 while (limit-- > 0) {
 262                         long status = hypervisor_con_putchar(CON_BREAK);
 263                         if (status == HV_EOK)
 264                                 break;
 265                         udelay(2);
 266                 }
 267
 268                 spin_unlock_irqrestore(&port->lock, flags);
 269         }
 270 }
 271
 272 /* port->lock is not held.  */
 273 static int sunhv_startup(struct uart_port *port)
 274 {
 275         return 0;
 276 }
 277
 278 /* port->lock is not held.  */
 279 static void sunhv_shutdown(struct uart_port *port)
 280 {
 281 }
 282
 283 /* port->lock is not held.  */
 284 static void sunhv_set_termios(struct uart_port *port, struct termios *termios,
 285                               struct termios *old)
 286 {
 287         unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 288         unsigned int quot = uart_get_divisor(port, baud);
 289         unsigned int iflag, cflag;
 290         unsigned long flags;
 291
 292         spin_lock_irqsave(&port->lock, flags);
 293
 294         iflag = termios->c_iflag;
 295         cflag = termios->c_cflag;
 296
 297         port->ignore_status_mask = 0;
 298         if (iflag & IGNBRK)
 299                 port->ignore_status_mask |= IGNORE_BREAK;
 300         if ((cflag & CREAD) == 0)
 301                 port->ignore_status_mask |= IGNORE_ALL;
 302
 303         /* XXX */
 304         uart_update_timeout(port, cflag,
 305                             (port->uartclk / (16 * quot)));
 306
 307         spin_unlock_irqrestore(&port->lock, flags);
 308 }
 309
 310 static const char *sunhv_type(struct uart_port *port)
 311 {
 312         return "SUN4V HCONS";
 313 }
 314
 315 static void sunhv_release_port(struct uart_port *port)
 316 {
 317 }
 318
 319 static int sunhv_request_port(struct uart_port *port)
 320 {
 321         return 0;
 322 }
 323
 324 static void sunhv_config_port(struct uart_port *port, int flags)
 325 {
 326 }
 327
 328 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
 329 {
 330         return -EINVAL;
 331 }
 332
 333 static struct uart_ops sunhv_pops = {
 334         .tx_empty       = sunhv_tx_empty,
 335         .set_mctrl      = sunhv_set_mctrl,
 336         .get_mctrl      = sunhv_get_mctrl,
 337         .stop_tx        = sunhv_stop_tx,
 338         .start_tx       = sunhv_start_tx,
 339         .send_xchar     = sunhv_send_xchar,
 340         .stop_rx        = sunhv_stop_rx,
 341         .enable_ms      = sunhv_enable_ms,
 342         .break_ctl      = sunhv_break_ctl,
 343         .startup        = sunhv_startup,
 344         .shutdown       = sunhv_shutdown,
 345         .set_termios    = sunhv_set_termios,
 346         .type           = sunhv_type,
 347         .release_port   = sunhv_release_port,
 348         .request_port   = sunhv_request_port,
 349         .config_port    = sunhv_config_port,
 350         .verify_port    = sunhv_verify_port,
 351 };
 352
 353 static struct uart_driver sunhv_reg = {
 354         .owner                  = THIS_MODULE,
 355         .driver_name            = "serial",
 356         .devfs_name             = "tts/",
 357         .dev_name               = "ttyS",
 358         .major                  = TTY_MAJOR,
 359 };
 360
 361 static struct uart_port *sunhv_port;
 362
 363 static inline void sunhv_console_putchar(struct uart_port *port, char c)
 364 {
 365         unsigned long flags;
 366         int limit = 1000000;
 367
 368         spin_lock_irqsave(&port->lock, flags);
 369
 370         while (limit-- > 0) {
 371                 long status = hypervisor_con_putchar(c);
 372                 if (status == HV_EOK)
 373                         break;
 374                 udelay(2);
 375         }
 376
 377         spin_unlock_irqrestore(&port->lock, flags);
 378 }
 379
 380 static void sunhv_console_write(struct console *con, const char *s, unsigned n)
 381 {
 382         struct uart_port *port = sunhv_port;
 383         int i;
 384
 385         for (i = 0; i < n; i++) {
 386                 if (*s == '\n')
 387                         sunhv_console_putchar(port, '\r');
 388                 sunhv_console_putchar(port, *s++);
 389         }
 390 }
 391
 392 static struct console sunhv_console = {
 393         .name   =       "ttyHV",
 394         .write  =       sunhv_console_write,
 395         .device =       uart_console_device,
 396         .flags  =       CON_PRINTBUFFER,
 397         .index  =       -1,
 398         .data   =       &sunhv_reg,
 399 };
 400
 401 static inline struct console *SUNHV_CONSOLE(void)
 402 {
 403         if (con_is_present())
 404                 return NULL;
 405
 406         sunhv_console.index = 0;
 407
 408         return &sunhv_console;
 409 }
 410
 411 static int __init hv_console_compatible(char *buf, int len)
 412 {
 413         while (len) {
 414                 int this_len;
 415
 416                 if (!strcmp(buf, "qcn"))
 417                         return 1;
 418
 419                 this_len = strlen(buf) + 1;
 420
 421                 buf += this_len;
 422                 len -= this_len;
 423         }
 424
 425         return 0;
 426 }
 427
 428 static unsigned int __init get_interrupt(void)
 429 {
 430         struct device_node *dev_node;
 431
 432         dev_node = sun4v_vdev_root->child;
 433         while (dev_node != NULL) {
 434                 struct property *prop;
 435
 436                 if (strcmp(dev_node->name, "console"))
 437                         goto next_sibling;
 438
 439                 prop = of_find_property(dev_node, "compatible", NULL);
 440                 if (!prop)
 441                         goto next_sibling;
 442
 443                 if (hv_console_compatible(prop->value, prop->length))
 444                         break;
 445
 446         next_sibling:
 447                 dev_node = dev_node->sibling;
 448         }
 449         if (!dev_node)
 450                 return 0;
 451
 452         /* Ok, the this is the OBP node for the sun4v hypervisor
 453          * console device.  Decode the interrupt.
 454          */
 455         return sun4v_vdev_device_interrupt(dev_node);
 456 }
 457
 458 static int __init sunhv_init(void)
 459 {
 460         struct uart_port *port;
 461         int ret;
 462
 463         if (tlb_type != hypervisor)
 464                 return -ENODEV;
 465
 466         port = kmalloc(sizeof(struct uart_port), GFP_KERNEL);
 467         if (unlikely(!port))
 468                 return -ENOMEM;
 469
 470         memset(port, 0, sizeof(struct uart_port));
 471
 472         port->line = 0;
 473         port->ops = &sunhv_pops;
 474         port->type = PORT_SUNHV;
 475         port->uartclk = ( 29491200 / 16 ); /* arbitrary */
 476
 477         /* Set this just to make uart_configure_port() happy.  */
 478         port->membase = (unsigned char __iomem *) __pa(port);
 479
 480         port->irq = get_interrupt();
 481         if (!port->irq) {
 482                 kfree(port);
 483                 return -ENODEV;
 484         }
 485
 486         sunhv_reg.minor = sunserial_current_minor;
 487         sunhv_reg.nr = 1;
 488
 489         ret = uart_register_driver(&sunhv_reg);
 490         if (ret < 0) {
 491                 printk(KERN_ERR "SUNHV: uart_register_driver() failed %d\n",
 492                        ret);
 493                 kfree(port);
 494
 495                 return ret;
 496         }
 497
 498         sunhv_reg.tty_driver->name_base = sunhv_reg.minor - 64;
 499         sunserial_current_minor += 1;
 500
 501         sunhv_reg.cons = SUNHV_CONSOLE();
 502
 503         sunhv_port = port;
 504
 505         ret = uart_add_one_port(&sunhv_reg, port);
 506         if (ret < 0) {
 507                 printk(KERN_ERR "SUNHV: uart_add_one_port() failed %d\n", ret);
 508                 sunserial_current_minor -= 1;
 509                 uart_unregister_driver(&sunhv_reg);
 510                 kfree(port);
 511                 sunhv_port = NULL;
 512                 return -ENODEV;
 513         }
 514
 515         if (request_irq(port->irq, sunhv_interrupt,
 516                         SA_SHIRQ, "serial(sunhv)", port)) {
 517                 printk(KERN_ERR "sunhv: Cannot register IRQ\n");
 518                 uart_remove_one_port(&sunhv_reg, port);
 519                 sunserial_current_minor -= 1;
 520                 uart_unregister_driver(&sunhv_reg);
 521                 kfree(port);
 522                 sunhv_port = NULL;
 523                 return -ENODEV;
 524         }
 525
 526         return 0;
 527 }
 528
 529 static void __exit sunhv_exit(void)
 530 {
 531         struct uart_port *port = sunhv_port;
 532
 533         BUG_ON(!port);
 534
 535         free_irq(port->irq, port);
 536
 537         uart_remove_one_port(&sunhv_reg, port);
 538         sunserial_current_minor -= 1;
 539
 540         uart_unregister_driver(&sunhv_reg);
 541
 542         kfree(sunhv_port);
 543         sunhv_port = NULL;
 544 }
 545
 546 module_init(sunhv_init);
 547 module_exit(sunhv_exit);
 548
 549 MODULE_AUTHOR("David S. Miller");
 550 MODULE_DESCRIPTION("SUN4V Hypervisor console driver")
 551 MODULE_LICENSE("GPL");