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/irq.h>
  25
  26 #if defined(CONFIG_MAGIC_SYSRQ)
  27 #define SUPPORT_SYSRQ
  28 #endif
  29
  30 #include <linux/serial_core.h>
  31
  32 #include "suncore.h"
  33
  34 #define CON_BREAK       ((long)-1)
  35 #define CON_HUP         ((long)-2)
  36
  37 static inline long hypervisor_con_getchar(long *status)
  38 {
  39         register unsigned long func asm("%o5");
  40         register unsigned long arg0 asm("%o0");
  41         register unsigned long arg1 asm("%o1");
  42
  43         func = HV_FAST_CONS_GETCHAR;
  44         arg0 = 0;
  45         arg1 = 0;
  46         __asm__ __volatile__("ta        %6"
  47                              : "=&r" (func), "=&r" (arg0), "=&r" (arg1)
  48                              : "0" (func), "1" (arg0), "2" (arg1),
  49                                "i" (HV_FAST_TRAP));
  50
  51         *status = arg0;
  52
  53         return (long) arg1;
  54 }
  55
  56 static inline long hypervisor_con_putchar(long ch)
  57 {
  58         register unsigned long func asm("%o5");
  59         register unsigned long arg0 asm("%o0");
  60
  61         func = HV_FAST_CONS_PUTCHAR;
  62         arg0 = ch;
  63         __asm__ __volatile__("ta        %4"
  64                              : "=&r" (func), "=&r" (arg0)
  65                              : "0" (func), "1" (arg0), "i" (HV_FAST_TRAP));
  66
  67         return (long) arg0;
  68 }
  69
  70 #define IGNORE_BREAK    0x1
  71 #define IGNORE_ALL      0x2
  72
  73 static int hung_up = 0;
  74
  75 static struct tty_struct *receive_chars(struct uart_port *port, struct pt_regs *regs)
  76 {
  77         struct tty_struct *tty = NULL;
  78         int saw_console_brk = 0;
  79         int limit = 10000;
  80
  81         if (port->info != NULL)         /* Unopened serial console */
  82                 tty = port->info->tty;
  83
  84         while (limit-- > 0) {
  85                 long status;
  86                 long c = hypervisor_con_getchar(&status);
  87                 unsigned char flag;
  88
  89                 if (status == HV_EWOULDBLOCK)
  90                         break;
  91
  92                 if (c == CON_BREAK) {
  93                         saw_console_brk = 1;
  94                         c = 0;
  95                 }
  96
  97                 if (c == CON_HUP) {
  98                         hung_up = 1;
  99                         uart_handle_dcd_change(port, 0);
 100                 } else if (hung_up) {
 101                         hung_up = 0;
 102                         uart_handle_dcd_change(port, 1);
 103                 }
 104
 105                 if (tty == NULL) {
 106                         uart_handle_sysrq_char(port, c, regs);
 107                         continue;
 108                 }
 109
 110                 flag = TTY_NORMAL;
 111                 port->icount.rx++;
 112                 if (c == CON_BREAK) {
 113                         port->icount.brk++;
 114                         if (uart_handle_break(port))
 115                                 continue;
 116                         flag = TTY_BREAK;
 117                 }
 118
 119                 if (uart_handle_sysrq_char(port, c, regs))
 120                         continue;
 121
 122                 if ((port->ignore_status_mask & IGNORE_ALL) ||
 123                     ((port->ignore_status_mask & IGNORE_BREAK) &&
 124                      (c == CON_BREAK)))
 125                         continue;
 126
 127                 tty_insert_flip_char(tty, c, flag);
 128         }
 129
 130         if (saw_console_brk)
 131                 sun_do_break();
 132
 133         return tty;
 134 }
 135
 136 static void transmit_chars(struct uart_port *port)
 137 {
 138         struct circ_buf *xmit = &port->info->xmit;
 139
 140         if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 141                 return;
 142
 143         while (!uart_circ_empty(xmit)) {
 144                 long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
 145
 146                 if (status != HV_EOK)
 147                         break;
 148
 149                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 150                 port->icount.tx++;
 151         }
 152
 153         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 154                 uart_write_wakeup(port);
 155 }
 156
 157 static irqreturn_t sunhv_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 158 {
 159         struct uart_port *port = dev_id;
 160         struct tty_struct *tty;
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&port->lock, flags);
 164         tty = receive_chars(port, regs);
 165         transmit_chars(port);
 166         spin_unlock_irqrestore(&port->lock, flags);
 167
 168         if (tty)
 169                 tty_flip_buffer_push(tty);
 170
 171         return IRQ_HANDLED;
 172 }
 173
 174 /* port->lock is not held.  */
 175 static unsigned int sunhv_tx_empty(struct uart_port *port)
 176 {
 177         /* Transmitter is always empty for us.  If the circ buffer
 178          * is non-empty or there is an x_char pending, our caller
 179          * will do the right thing and ignore what we return here.
 180          */
 181         return TIOCSER_TEMT;
 182 }
 183
 184 /* port->lock held by caller.  */
 185 static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
 186 {
 187         return;
 188 }
 189
 190 /* port->lock is held by caller and interrupts are disabled.  */
 191 static unsigned int sunhv_get_mctrl(struct uart_port *port)
 192 {
 193         return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
 194 }
 195
 196 /* port->lock held by caller.  */
 197 static void sunhv_stop_tx(struct uart_port *port)
 198 {
 199         return;
 200 }
 201
 202 /* port->lock held by caller.  */
 203 static void sunhv_start_tx(struct uart_port *port)
 204 {
 205         struct circ_buf *xmit = &port->info->xmit;
 206         unsigned long flags;
 207
 208         spin_lock_irqsave(&port->lock, flags);
 209
 210         while (!uart_circ_empty(xmit)) {
 211                 long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
 212
 213                 if (status != HV_EOK)
 214                         break;
 215
 216                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 217                 port->icount.tx++;
 218         }
 219
 220         spin_unlock_irqrestore(&port->lock, flags);
 221 }
 222
 223 /* port->lock is not held.  */
 224 static void sunhv_send_xchar(struct uart_port *port, char ch)
 225 {
 226         unsigned long flags;
 227         int limit = 10000;
 228
 229         spin_lock_irqsave(&port->lock, flags);
 230
 231         while (limit-- > 0) {
 232                 long status = hypervisor_con_putchar(ch);
 233                 if (status == HV_EOK)
 234                         break;
 235         }
 236
 237         spin_unlock_irqrestore(&port->lock, flags);
 238 }
 239
 240 /* port->lock held by caller.  */
 241 static void sunhv_stop_rx(struct uart_port *port)
 242 {
 243 }
 244
 245 /* port->lock held by caller.  */
 246 static void sunhv_enable_ms(struct uart_port *port)
 247 {
 248 }
 249
 250 /* port->lock is not held.  */
 251 static void sunhv_break_ctl(struct uart_port *port, int break_state)
 252 {
 253         if (break_state) {
 254                 unsigned long flags;
 255                 int limit = 10000;
 256
 257                 spin_lock_irqsave(&port->lock, flags);
 258
 259                 while (limit-- > 0) {
 260                         long status = hypervisor_con_putchar(CON_BREAK);
 261                         if (status == HV_EOK)
 262                                 break;
 263                 }
 264
 265                 spin_unlock_irqrestore(&port->lock, flags);
 266         }
 267 }
 268
 269 /* port->lock is not held.  */
 270 static int sunhv_startup(struct uart_port *port)
 271 {
 272         return 0;
 273 }
 274
 275 /* port->lock is not held.  */
 276 static void sunhv_shutdown(struct uart_port *port)
 277 {
 278 }
 279
 280 /* port->lock is not held.  */
 281 static void sunhv_set_termios(struct uart_port *port, struct termios *termios,
 282                               struct termios *old)
 283 {
 284         unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 285         unsigned int quot = uart_get_divisor(port, baud);
 286         unsigned int iflag, cflag;
 287         unsigned long flags;
 288
 289         spin_lock_irqsave(&port->lock, flags);
 290
 291         iflag = termios->c_iflag;
 292         cflag = termios->c_cflag;
 293
 294         port->ignore_status_mask = 0;
 295         if (iflag & IGNBRK)
 296                 port->ignore_status_mask |= IGNORE_BREAK;
 297         if ((cflag & CREAD) == 0)
 298                 port->ignore_status_mask |= IGNORE_ALL;
 299
 300         /* XXX */
 301         uart_update_timeout(port, cflag,
 302                             (port->uartclk / (16 * quot)));
 303
 304         spin_unlock_irqrestore(&port->lock, flags);
 305 }
 306
 307 static const char *sunhv_type(struct uart_port *port)
 308 {
 309         return "SUN4V HCONS";
 310 }
 311
 312 static void sunhv_release_port(struct uart_port *port)
 313 {
 314 }
 315
 316 static int sunhv_request_port(struct uart_port *port)
 317 {
 318         return 0;
 319 }
 320
 321 static void sunhv_config_port(struct uart_port *port, int flags)
 322 {
 323 }
 324
 325 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
 326 {
 327         return -EINVAL;
 328 }
 329
 330 static struct uart_ops sunhv_pops = {
 331         .tx_empty       = sunhv_tx_empty,
 332         .set_mctrl      = sunhv_set_mctrl,
 333         .get_mctrl      = sunhv_get_mctrl,
 334         .stop_tx        = sunhv_stop_tx,
 335         .start_tx       = sunhv_start_tx,
 336         .send_xchar     = sunhv_send_xchar,
 337         .stop_rx        = sunhv_stop_rx,
 338         .enable_ms      = sunhv_enable_ms,
 339         .break_ctl      = sunhv_break_ctl,
 340         .startup        = sunhv_startup,
 341         .shutdown       = sunhv_shutdown,
 342         .set_termios    = sunhv_set_termios,
 343         .type           = sunhv_type,
 344         .release_port   = sunhv_release_port,
 345         .request_port   = sunhv_request_port,
 346         .config_port    = sunhv_config_port,
 347         .verify_port    = sunhv_verify_port,
 348 };
 349
 350 static struct uart_driver sunhv_reg = {
 351         .owner                  = THIS_MODULE,
 352         .driver_name            = "serial",
 353         .devfs_name             = "tts/",
 354         .dev_name               = "ttyS",
 355         .major                  = TTY_MAJOR,
 356 };
 357
 358 static struct uart_port *sunhv_port;
 359
 360 static inline void sunhv_console_putchar(struct uart_port *port, char c)
 361 {
 362         unsigned long flags;
 363         int limit = 10000;
 364
 365         spin_lock_irqsave(&port->lock, flags);
 366
 367         while (limit-- > 0) {
 368                 long status = hypervisor_con_putchar(c);
 369                 if (status == HV_EOK)
 370                         break;
 371         }
 372
 373         spin_unlock_irqrestore(&port->lock, flags);
 374 }
 375
 376 static void sunhv_console_write(struct console *con, const char *s, unsigned n)
 377 {
 378         struct uart_port *port = sunhv_port;
 379         int i;
 380
 381         for (i = 0; i < n; i++) {
 382                 if (*s == '\n')
 383                         sunhv_console_putchar(port, '\r');
 384                 sunhv_console_putchar(port, *s++);
 385         }
 386 }
 387
 388 static int sunhv_console_setup(struct console *con, char *options)
 389 {
 390         return 0;
 391 }
 392
 393 static struct console sunhv_console = {
 394         .name   =       "ttyS",
 395         .write  =       sunhv_console_write,
 396         .device =       uart_console_device,
 397         .setup  =       sunhv_console_setup,
 398         .flags  =       CON_PRINTBUFFER,
 399         .index  =       -1,
 400         .data   =       &sunhv_reg,
 401 };
 402
 403 static void __init sunhv_console_init(void)
 404 {
 405         if (con_is_present())
 406                 return;
 407
 408         sunhv_console.index = 0;
 409         register_console(&sunhv_console);
 410 }
 411
 412 static int __init hv_console_compatible(char *buf, int len)
 413 {
 414         while (len) {
 415                 int this_len;
 416
 417                 if (!strcmp(buf, "qcn"))
 418                         return 1;
 419
 420                 this_len = strlen(buf) + 1;
 421
 422                 buf += this_len;
 423                 len -= this_len;
 424         }
 425
 426         return 0;
 427 }
 428
 429 static unsigned int __init get_interrupt(void)
 430 {
 431         const char *cons_str = "console";
 432         const char *compat_str = "compatible";
 433         int node = prom_getchild(sun4v_vdev_root);
 434         unsigned int irq;
 435         char buf[64];
 436         int err, len;
 437
 438         node = prom_searchsiblings(node, cons_str);
 439         if (!node)
 440                 return 0;
 441
 442         len = prom_getproplen(node, compat_str);
 443         if (len == 0 || len == -1)
 444                 return 0;
 445
 446         err = prom_getproperty(node, compat_str, buf, 64);
 447         if (err == -1)
 448                 return 0;
 449
 450         if (!hv_console_compatible(buf, len))
 451                 return 0;
 452
 453         /* Ok, the this is the OBP node for the sun4v hypervisor
 454          * console device.  Decode the interrupt.
 455          */
 456         err = prom_getproperty(node, "interrupts",
 457                                (char *) &irq, sizeof(irq));
 458         if (err == -1)
 459                 return 0;
 460
 461         return sun4v_build_irq(sun4v_vdev_devhandle, irq, 4, 0);
 462 }
 463
 464 static u32 sunhv_irq;
 465
 466 static int __init sunhv_init(void)
 467 {
 468         struct uart_port *port;
 469         int ret;
 470
 471         if (tlb_type != hypervisor)
 472                 return -ENODEV;
 473
 474         sunhv_irq = get_interrupt();
 475         if (!sunhv_irq)
 476                 return -ENODEV;
 477
 478         port = kmalloc(sizeof(struct uart_port), GFP_KERNEL);
 479         if (unlikely(!port))
 480                 return -ENOMEM;
 481
 482         port->line = 0;
 483         port->ops = &sunhv_pops;
 484         port->type = PORT_SUNHV;
 485         port->uartclk = ( 29491200 / 16 ); /* arbitrary */
 486
 487         if (request_irq(sunhv_irq, sunhv_interrupt,
 488                         SA_SHIRQ, "serial(sunhv)", port)) {
 489                 printk("sunhv: Cannot get IRQ %x\n", sunhv_irq);
 490                 kfree(port);
 491                 return -ENODEV;
 492         }
 493
 494         printk("SUNHV: SUN4V virtual console, IRQ[%08x]\n",
 495                sunhv_irq);
 496
 497         sunhv_reg.minor = sunserial_current_minor;
 498         sunhv_reg.nr = 1;
 499         sunhv_reg.cons = &sunhv_console;
 500
 501         ret = uart_register_driver(&sunhv_reg);
 502         if (ret < 0) {
 503                 free_irq(sunhv_irq, up);
 504                 kfree(port);
 505
 506                 return ret;
 507         }
 508
 509         sunhv_port = port;
 510
 511         sunserial_current_minor += 1;
 512
 513         sunhv_console_init();
 514
 515         uart_add_one_port(&sunhv_reg, port);
 516
 517         return 0;
 518 }
 519
 520 static void __exit sunhv_exit(void)
 521 {
 522         struct uart_port *port = sunhv_port;
 523
 524         BUG_ON(!port);
 525
 526         uart_remove_one_port(&sunhv_reg, port);
 527         free_irq(sunhv_irq, port);
 528
 529         sunserial_current_minor -= 1;
 530
 531         uart_unregister_driver(&sunhv_reg);
 532
 533         kfree(sunhv_port);
 534         sunhv_port = NULL;
 535 }
 536
 537 module_init(sunhv_init);
 538 module_exit(sunhv_exit);
 539
 540 MODULE_AUTHOR("David S. Miller");
 541 MODULE_DESCRIPTION("SUN4V Hypervisor console driver")
 542 MODULE_LICENSE("GPL");