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Linux/drivers/tty/serial/sunhv.c

  1 /* sunhv.c: Serial driver for SUN4V hypervisor console.
  2  *
  3  * Copyright (C) 2006, 2007 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 #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 #if defined(CONFIG_MAGIC_SYSRQ)
 29 #define SUPPORT_SYSRQ
 30 #endif
 31 
 32 #include <linux/serial_core.h>
 33 #include <linux/sunserialcore.h>
 34 
 35 #define CON_BREAK       ((long)-1)
 36 #define CON_HUP         ((long)-2)
 37 
 38 #define IGNORE_BREAK    0x1
 39 #define IGNORE_ALL      0x2
 40 
 41 static char *con_write_page;
 42 static char *con_read_page;
 43 
 44 static int hung_up = 0;
 45 
 46 static void transmit_chars_putchar(struct uart_port *port, struct circ_buf *xmit)
 47 {
 48         while (!uart_circ_empty(xmit)) {
 49                 long status = sun4v_con_putchar(xmit->buf[xmit->tail]);
 50 
 51                 if (status != HV_EOK)
 52                         break;
 53 
 54                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 55                 port->icount.tx++;
 56         }
 57 }
 58 
 59 static void transmit_chars_write(struct uart_port *port, struct circ_buf *xmit)
 60 {
 61         while (!uart_circ_empty(xmit)) {
 62                 unsigned long ra = __pa(xmit->buf + xmit->tail);
 63                 unsigned long len, status, sent;
 64 
 65                 len = CIRC_CNT_TO_END(xmit->head, xmit->tail,
 66                                       UART_XMIT_SIZE);
 67                 status = sun4v_con_write(ra, len, &sent);
 68                 if (status != HV_EOK)
 69                         break;
 70                 xmit->tail = (xmit->tail + sent) & (UART_XMIT_SIZE - 1);
 71                 port->icount.tx += sent;
 72         }
 73 }
 74 
 75 static int receive_chars_getchar(struct uart_port *port)
 76 {
 77         int saw_console_brk = 0;
 78         int limit = 10000;
 79 
 80         while (limit-- > 0) {
 81                 long status;
 82                 long c = sun4v_con_getchar(&status);
 83 
 84                 if (status == HV_EWOULDBLOCK)
 85                         break;
 86 
 87                 if (c == CON_BREAK) {
 88                         if (uart_handle_break(port))
 89                                 continue;
 90                         saw_console_brk = 1;
 91                         c = 0;
 92                 }
 93 
 94                 if (c == CON_HUP) {
 95                         hung_up = 1;
 96                         uart_handle_dcd_change(port, 0);
 97                 } else if (hung_up) {
 98                         hung_up = 0;
 99                         uart_handle_dcd_change(port, 1);
100                 }
101 
102                 if (port->state == NULL) {
103                         uart_handle_sysrq_char(port, c);
104                         continue;
105                 }
106 
107                 port->icount.rx++;
108 
109                 if (uart_handle_sysrq_char(port, c))
110                         continue;
111 
112                 tty_insert_flip_char(&port->state->port, c, TTY_NORMAL);
113         }
114 
115         return saw_console_brk;
116 }
117 
118 static int receive_chars_read(struct uart_port *port)
119 {
120         int saw_console_brk = 0;
121         int limit = 10000;
122 
123         while (limit-- > 0) {
124                 unsigned long ra = __pa(con_read_page);
125                 unsigned long bytes_read, i;
126                 long stat = sun4v_con_read(ra, PAGE_SIZE, &bytes_read);
127 
128                 if (stat != HV_EOK) {
129                         bytes_read = 0;
130 
131                         if (stat == CON_BREAK) {
132                                 if (uart_handle_break(port))
133                                         continue;
134                                 saw_console_brk = 1;
135                                 *con_read_page = 0;
136                                 bytes_read = 1;
137                         } else if (stat == CON_HUP) {
138                                 hung_up = 1;
139                                 uart_handle_dcd_change(port, 0);
140                                 continue;
141                         } else {
142                                 /* HV_EWOULDBLOCK, etc.  */
143                                 break;
144                         }
145                 }
146 
147                 if (hung_up) {
148                         hung_up = 0;
149                         uart_handle_dcd_change(port, 1);
150                 }
151 
152                 for (i = 0; i < bytes_read; i++)
153                         uart_handle_sysrq_char(port, con_read_page[i]);
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 struct sunhv_ops bychar_ops = {
173         .transmit_chars = transmit_chars_putchar,
174         .receive_chars = receive_chars_getchar,
175 };
176 
177 static struct sunhv_ops bywrite_ops = {
178         .transmit_chars = transmit_chars_write,
179         .receive_chars = receive_chars_read,
180 };
181 
182 static 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         spin_lock_irqsave(&port->lock, flags);
221         tport = receive_chars(port);
222         transmit_chars(port);
223         spin_unlock_irqrestore(&port->lock, 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         spin_lock_irqsave(&port->lock, flags);
272 
273         while (limit-- > 0) {
274                 long status = sun4v_con_putchar(ch);
275                 if (status == HV_EOK)
276                         break;
277                 udelay(1);
278         }
279 
280         spin_unlock_irqrestore(&port->lock, flags);
281 }
282 
283 /* port->lock held by caller.  */
284 static void sunhv_stop_rx(struct uart_port *port)
285 {
286 }
287 
288 /* port->lock is not held.  */
289 static void sunhv_break_ctl(struct uart_port *port, int break_state)
290 {
291         if (break_state) {
292                 unsigned long flags;
293                 int limit = 10000;
294 
295                 spin_lock_irqsave(&port->lock, flags);
296 
297                 while (limit-- > 0) {
298                         long status = sun4v_con_putchar(CON_BREAK);
299                         if (status == HV_EOK)
300                                 break;
301                         udelay(1);
302                 }
303 
304                 spin_unlock_irqrestore(&port->lock, flags);
305         }
306 }
307 
308 /* port->lock is not held.  */
309 static int sunhv_startup(struct uart_port *port)
310 {
311         return 0;
312 }
313 
314 /* port->lock is not held.  */
315 static void sunhv_shutdown(struct uart_port *port)
316 {
317 }
318 
319 /* port->lock is not held.  */
320 static void sunhv_set_termios(struct uart_port *port, struct ktermios *termios,
321                               struct ktermios *old)
322 {
323         unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
324         unsigned int quot = uart_get_divisor(port, baud);
325         unsigned int iflag, cflag;
326         unsigned long flags;
327 
328         spin_lock_irqsave(&port->lock, flags);
329 
330         iflag = termios->c_iflag;
331         cflag = termios->c_cflag;
332 
333         port->ignore_status_mask = 0;
334         if (iflag & IGNBRK)
335                 port->ignore_status_mask |= IGNORE_BREAK;
336         if ((cflag & CREAD) == 0)
337                 port->ignore_status_mask |= IGNORE_ALL;
338 
339         /* XXX */
340         uart_update_timeout(port, cflag,
341                             (port->uartclk / (16 * quot)));
342 
343         spin_unlock_irqrestore(&port->lock, flags);
344 }
345 
346 static const char *sunhv_type(struct uart_port *port)
347 {
348         return "SUN4V HCONS";
349 }
350 
351 static void sunhv_release_port(struct uart_port *port)
352 {
353 }
354 
355 static int sunhv_request_port(struct uart_port *port)
356 {
357         return 0;
358 }
359 
360 static void sunhv_config_port(struct uart_port *port, int flags)
361 {
362 }
363 
364 static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
365 {
366         return -EINVAL;
367 }
368 
369 static struct uart_ops sunhv_pops = {
370         .tx_empty       = sunhv_tx_empty,
371         .set_mctrl      = sunhv_set_mctrl,
372         .get_mctrl      = sunhv_get_mctrl,
373         .stop_tx        = sunhv_stop_tx,
374         .start_tx       = sunhv_start_tx,
375         .send_xchar     = sunhv_send_xchar,
376         .stop_rx        = sunhv_stop_rx,
377         .break_ctl      = sunhv_break_ctl,
378         .startup        = sunhv_startup,
379         .shutdown       = sunhv_shutdown,
380         .set_termios    = sunhv_set_termios,
381         .type           = sunhv_type,
382         .release_port   = sunhv_release_port,
383         .request_port   = sunhv_request_port,
384         .config_port    = sunhv_config_port,
385         .verify_port    = sunhv_verify_port,
386 };
387 
388 static struct uart_driver sunhv_reg = {
389         .owner                  = THIS_MODULE,
390         .driver_name            = "sunhv",
391         .dev_name               = "ttyS",
392         .major                  = TTY_MAJOR,
393 };
394 
395 static struct uart_port *sunhv_port;
396 
397 /* Copy 's' into the con_write_page, decoding "\n" into
398  * "\r\n" along the way.  We have to return two lengths
399  * because the caller needs to know how much to advance
400  * 's' and also how many bytes to output via con_write_page.
401  */
402 static int fill_con_write_page(const char *s, unsigned int n,
403                                unsigned long *page_bytes)
404 {
405         const char *orig_s = s;
406         char *p = con_write_page;
407         int left = PAGE_SIZE;
408 
409         while (n--) {
410                 if (*s == '\n') {
411                         if (left < 2)
412                                 break;
413                         *p++ = '\r';
414                         left--;
415                 } else if (left < 1)
416                         break;
417                 *p++ = *s++;
418                 left--;
419         }
420         *page_bytes = p - con_write_page;
421         return s - orig_s;
422 }
423 
424 static void sunhv_console_write_paged(struct console *con, const char *s, unsigned n)
425 {
426         struct uart_port *port = sunhv_port;
427         unsigned long flags;
428         int locked = 1;
429 
430         if (port->sysrq || oops_in_progress)
431                 locked = spin_trylock_irqsave(&port->lock, flags);
432         else
433                 spin_lock_irqsave(&port->lock, flags);
434 
435         while (n > 0) {
436                 unsigned long ra = __pa(con_write_page);
437                 unsigned long page_bytes;
438                 unsigned int cpy = fill_con_write_page(s, n,
439                                                        &page_bytes);
440 
441                 n -= cpy;
442                 s += cpy;
443                 while (page_bytes > 0) {
444                         unsigned long written;
445                         int limit = 1000000;
446 
447                         while (limit--) {
448                                 unsigned long stat;
449 
450                                 stat = sun4v_con_write(ra, page_bytes,
451                                                        &written);
452                                 if (stat == HV_EOK)
453                                         break;
454                                 udelay(1);
455                         }
456                         if (limit < 0)
457                                 break;
458                         page_bytes -= written;
459                         ra += written;
460                 }
461         }
462 
463         if (locked)
464                 spin_unlock_irqrestore(&port->lock, flags);
465 }
466 
467 static inline void sunhv_console_putchar(struct uart_port *port, char c)
468 {
469         int limit = 1000000;
470 
471         while (limit-- > 0) {
472                 long status = sun4v_con_putchar(c);
473                 if (status == HV_EOK)
474                         break;
475                 udelay(1);
476         }
477 }
478 
479 static void sunhv_console_write_bychar(struct console *con, const char *s, unsigned n)
480 {
481         struct uart_port *port = sunhv_port;
482         unsigned long flags;
483         int i, locked = 1;
484 
485         if (port->sysrq || oops_in_progress)
486                 locked = spin_trylock_irqsave(&port->lock, flags);
487         else
488                 spin_lock_irqsave(&port->lock, flags);
489         if (port->sysrq) {
490                 locked = 0;
491         } else if (oops_in_progress) {
492                 locked = spin_trylock(&port->lock);
493         } else
494                 spin_lock(&port->lock);
495 
496         for (i = 0; i < n; i++) {
497                 if (*s == '\n')
498                         sunhv_console_putchar(port, '\r');
499                 sunhv_console_putchar(port, *s++);
500         }
501 
502         if (locked)
503                 spin_unlock_irqrestore(&port->lock, flags);
504 }
505 
506 static struct console sunhv_console = {
507         .name   =       "ttyHV",
508         .write  =       sunhv_console_write_bychar,
509         .device =       uart_console_device,
510         .flags  =       CON_PRINTBUFFER,
511         .index  =       -1,
512         .data   =       &sunhv_reg,
513 };
514 
515 static int hv_probe(struct platform_device *op)
516 {
517         struct uart_port *port;
518         unsigned long minor;
519         int err;
520 
521         if (op->archdata.irqs[0] == 0xffffffff)
522                 return -ENODEV;
523 
524         port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
525         if (unlikely(!port))
526                 return -ENOMEM;
527 
528         minor = 1;
529         if (sun4v_hvapi_register(HV_GRP_CORE, 1, &minor) == 0 &&
530             minor >= 1) {
531                 err = -ENOMEM;
532                 con_write_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
533                 if (!con_write_page)
534                         goto out_free_port;
535 
536                 con_read_page = kzalloc(PAGE_SIZE, GFP_KERNEL);
537                 if (!con_read_page)
538                         goto out_free_con_write_page;
539 
540                 sunhv_console.write = sunhv_console_write_paged;
541                 sunhv_ops = &bywrite_ops;
542         }
543 
544         sunhv_port = port;
545 
546         port->line = 0;
547         port->ops = &sunhv_pops;
548         port->type = PORT_SUNHV;
549         port->uartclk = ( 29491200 / 16 ); /* arbitrary */
550 
551         port->membase = (unsigned char __iomem *) __pa(port);
552 
553         port->irq = op->archdata.irqs[0];
554 
555         port->dev = &op->dev;
556 
557         err = sunserial_register_minors(&sunhv_reg, 1);
558         if (err)
559                 goto out_free_con_read_page;
560 
561         sunserial_console_match(&sunhv_console, op->dev.of_node,
562                                 &sunhv_reg, port->line, false);
563 
564         err = uart_add_one_port(&sunhv_reg, port);
565         if (err)
566                 goto out_unregister_driver;
567 
568         err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
569         if (err)
570                 goto out_remove_port;
571 
572         platform_set_drvdata(op, port);
573 
574         return 0;
575 
576 out_remove_port:
577         uart_remove_one_port(&sunhv_reg, port);
578 
579 out_unregister_driver:
580         sunserial_unregister_minors(&sunhv_reg, 1);
581 
582 out_free_con_read_page:
583         kfree(con_read_page);
584 
585 out_free_con_write_page:
586         kfree(con_write_page);
587 
588 out_free_port:
589         kfree(port);
590         sunhv_port = NULL;
591         return err;
592 }
593 
594 static int hv_remove(struct platform_device *dev)
595 {
596         struct uart_port *port = platform_get_drvdata(dev);
597 
598         free_irq(port->irq, port);
599 
600         uart_remove_one_port(&sunhv_reg, port);
601 
602         sunserial_unregister_minors(&sunhv_reg, 1);
603 
604         kfree(port);
605         sunhv_port = NULL;
606 
607         return 0;
608 }
609 
610 static const struct of_device_id hv_match[] = {
611         {
612                 .name = "console",
613                 .compatible = "qcn",
614         },
615         {
616                 .name = "console",
617                 .compatible = "SUNW,sun4v-console",
618         },
619         {},
620 };
621 MODULE_DEVICE_TABLE(of, hv_match);
622 
623 static struct platform_driver hv_driver = {
624         .driver = {
625                 .name = "hv",
626                 .owner = THIS_MODULE,
627                 .of_match_table = hv_match,
628         },
629         .probe          = hv_probe,
630         .remove         = hv_remove,
631 };
632 
633 static int __init sunhv_init(void)
634 {
635         if (tlb_type != hypervisor)
636                 return -ENODEV;
637 
638         return platform_driver_register(&hv_driver);
639 }
640 
641 static void __exit sunhv_exit(void)
642 {
643         platform_driver_unregister(&hv_driver);
644 }
645 
646 module_init(sunhv_init);
647 module_exit(sunhv_exit);
648 
649 MODULE_AUTHOR("David S. Miller");
650 MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
651 MODULE_VERSION("2.0");
652 MODULE_LICENSE("GPL");
653 

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