drivers/serial/sunhv.c

   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         .dev_name               = "ttyS",
 357         .major                  = TTY_MAJOR,
 358 };
 359
 360 static struct uart_port *sunhv_port;
 361
 362 static inline void sunhv_console_putchar(struct uart_port *port, char c)
 363 {
 364         unsigned long flags;
 365         int limit = 1000000;
 366
 367         spin_lock_irqsave(&port->lock, flags);
 368
 369         while (limit-- > 0) {
 370                 long status = hypervisor_con_putchar(c);
 371                 if (status == HV_EOK)
 372                         break;
 373                 udelay(2);
 374         }
 375
 376         spin_unlock_irqrestore(&port->lock, flags);
 377 }
 378
 379 static void sunhv_console_write(struct console *con, const char *s, unsigned n)
 380 {
 381         struct uart_port *port = sunhv_port;
 382         int i;
 383
 384         for (i = 0; i < n; i++) {
 385                 if (*s == '\n')
 386                         sunhv_console_putchar(port, '\r');
 387                 sunhv_console_putchar(port, *s++);
 388         }
 389 }
 390
 391 static struct console sunhv_console = {
 392         .name   =       "ttyHV",
 393         .write  =       sunhv_console_write,
 394         .device =       uart_console_device,
 395         .flags  =       CON_PRINTBUFFER,
 396         .index  =       -1,
 397         .data   =       &sunhv_reg,
 398 };
 399
 400 static inline struct console *SUNHV_CONSOLE(void)
 401 {
 402         if (con_is_present())
 403                 return NULL;
 404
 405         sunhv_console.index = 0;
 406
 407         return &sunhv_console;
 408 }
 409
 410 static int __init hv_console_compatible(char *buf, int len)
 411 {
 412         while (len) {
 413                 int this_len;
 414
 415                 if (!strcmp(buf, "qcn"))
 416                         return 1;
 417
 418                 this_len = strlen(buf) + 1;
 419
 420                 buf += this_len;
 421                 len -= this_len;
 422         }
 423
 424         return 0;
 425 }
 426
 427 static unsigned int __init get_interrupt(void)
 428 {
 429         struct device_node *dev_node;
 430
 431         dev_node = sun4v_vdev_root->child;
 432         while (dev_node != NULL) {
 433                 struct property *prop;
 434
 435                 if (strcmp(dev_node->name, "console"))
 436                         goto next_sibling;
 437
 438                 prop = of_find_property(dev_node, "compatible", NULL);
 439                 if (!prop)
 440                         goto next_sibling;
 441
 442                 if (hv_console_compatible(prop->value, prop->length))
 443                         break;
 444
 445         next_sibling:
 446                 dev_node = dev_node->sibling;
 447         }
 448         if (!dev_node)
 449                 return 0;
 450
 451         /* Ok, the this is the OBP node for the sun4v hypervisor
 452          * console device.  Decode the interrupt.
 453          */
 454         return sun4v_vdev_device_interrupt(dev_node);
 455 }
 456
 457 static int __init sunhv_init(void)
 458 {
 459         struct uart_port *port;
 460         int ret;
 461
 462         if (tlb_type != hypervisor)
 463                 return -ENODEV;
 464
 465         port = kmalloc(sizeof(struct uart_port), GFP_KERNEL);
 466         if (unlikely(!port))
 467                 return -ENOMEM;
 468
 469         memset(port, 0, sizeof(struct uart_port));
 470
 471         port->line = 0;
 472         port->ops = &sunhv_pops;
 473         port->type = PORT_SUNHV;
 474         port->uartclk = ( 29491200 / 16 ); /* arbitrary */
 475
 476         /* Set this just to make uart_configure_port() happy.  */
 477         port->membase = (unsigned char __iomem *) __pa(port);
 478
 479         port->irq = get_interrupt();
 480         if (!port->irq) {
 481                 kfree(port);
 482                 return -ENODEV;
 483         }
 484
 485         sunhv_reg.minor = sunserial_current_minor;
 486         sunhv_reg.nr = 1;
 487
 488         ret = uart_register_driver(&sunhv_reg);
 489         if (ret < 0) {
 490                 printk(KERN_ERR "SUNHV: uart_register_driver() failed %d\n",
 491                        ret);
 492                 kfree(port);
 493
 494                 return ret;
 495         }
 496
 497         sunhv_reg.tty_driver->name_base = sunhv_reg.minor - 64;
 498         sunserial_current_minor += 1;
 499
 500         sunhv_reg.cons = SUNHV_CONSOLE();
 501
 502         sunhv_port = port;
 503
 504         ret = uart_add_one_port(&sunhv_reg, port);
 505         if (ret < 0) {
 506                 printk(KERN_ERR "SUNHV: uart_add_one_port() failed %d\n", ret);
 507                 sunserial_current_minor -= 1;
 508                 uart_unregister_driver(&sunhv_reg);
 509                 kfree(port);
 510                 sunhv_port = NULL;
 511                 return -ENODEV;
 512         }
 513
 514         if (request_irq(port->irq, sunhv_interrupt,
 515                         SA_SHIRQ, "serial(sunhv)", port)) {
 516                 printk(KERN_ERR "sunhv: Cannot register IRQ\n");
 517                 uart_remove_one_port(&sunhv_reg, port);
 518                 sunserial_current_minor -= 1;
 519                 uart_unregister_driver(&sunhv_reg);
 520                 kfree(port);
 521                 sunhv_port = NULL;
 522                 return -ENODEV;
 523         }
 524
 525         return 0;
 526 }
 527
 528 static void __exit sunhv_exit(void)
 529 {
 530         struct uart_port *port = sunhv_port;
 531
 532         BUG_ON(!port);
 533
 534         free_irq(port->irq, port);
 535
 536         uart_remove_one_port(&sunhv_reg, port);
 537         sunserial_current_minor -= 1;
 538
 539         uart_unregister_driver(&sunhv_reg);
 540
 541         kfree(sunhv_port);
 542         sunhv_port = NULL;
 543 }
 544
 545 module_init(sunhv_init);
 546 module_exit(sunhv_exit);
 547
 548 MODULE_AUTHOR("David S. Miller");
 549 MODULE_DESCRIPTION("SUN4V Hypervisor console driver")
 550 MODULE_LICENSE("GPL");