2 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
3 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
4 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
5 * Copyright (C) 2004 IBM Corporation
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 #include <linux/console.h>
26 #include <linux/cpumask.h>
27 #include <linux/init.h>
28 #include <linux/kbd_kern.h>
29 #include <linux/kernel.h>
30 #include <linux/kthread.h>
31 #include <linux/list.h>
32 #include <linux/module.h>
33 #include <linux/major.h>
34 #include <linux/sysrq.h>
35 #include <linux/tty.h>
36 #include <linux/tty_flip.h>
37 #include <linux/sched.h>
38 #include <linux/spinlock.h>
39 #include <linux/delay.h>
40 #include <linux/freezer.h>
42 #include <asm/uaccess.h>
44 #include "hvc_console.h"
50 * Wait this long per iteration while trying to push buffered data to the
51 * hypervisor before allowing the tty to complete a close operation.
53 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
56 * These sizes are most efficient for vio, because they are the
57 * native transfer size. We could make them selectable in the
58 * future to better deal with backends that want other buffer sizes.
63 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
65 static struct tty_driver
*hvc_driver
;
66 static struct task_struct
*hvc_task
;
68 /* Picks up late kicks after list walk but before schedule() */
69 static int hvc_kicked
;
71 static int hvc_init(void);
73 #ifdef CONFIG_MAGIC_SYSRQ
74 static int sysrq_pressed
;
77 /* dynamic list of hvc_struct instances */
78 static LIST_HEAD(hvc_structs
);
81 * Protect the list of hvc_struct instances from inserts and removals during
84 static DEFINE_SPINLOCK(hvc_structs_lock
);
87 * This value is used to assign a tty->index value to a hvc_struct based
88 * upon order of exposure via hvc_probe(), when we can not match it to
89 * a console candidate registered with hvc_instantiate().
91 static int last_hvc
= -1;
94 * Do not call this function with either the hvc_structs_lock or the hvc_struct
95 * lock held. If successful, this function increments the kref reference
96 * count against the target hvc_struct so it should be released when finished.
98 static struct hvc_struct
*hvc_get_by_index(int index
)
100 struct hvc_struct
*hp
;
103 spin_lock(&hvc_structs_lock
);
105 list_for_each_entry(hp
, &hvc_structs
, next
) {
106 spin_lock_irqsave(&hp
->lock
, flags
);
107 if (hp
->index
== index
) {
109 spin_unlock_irqrestore(&hp
->lock
, flags
);
110 spin_unlock(&hvc_structs_lock
);
113 spin_unlock_irqrestore(&hp
->lock
, flags
);
117 spin_unlock(&hvc_structs_lock
);
123 * Initial console vtermnos for console API usage prior to full console
124 * initialization. Any vty adapter outside this range will not have usable
125 * console interfaces but can still be used as a tty device. This has to be
126 * static because kmalloc will not work during early console init.
128 static struct hv_ops
*cons_ops
[MAX_NR_HVC_CONSOLES
];
129 static uint32_t vtermnos
[MAX_NR_HVC_CONSOLES
] =
130 {[0 ... MAX_NR_HVC_CONSOLES
- 1] = -1};
133 * Console APIs, NOT TTY. These APIs are available immediately when
134 * hvc_console_setup() finds adapters.
137 static void hvc_console_print(struct console
*co
, const char *b
,
140 char c
[N_OUTBUF
] __ALIGNED__
;
141 unsigned i
= 0, n
= 0;
142 int r
, donecr
= 0, index
= co
->index
;
144 /* Console access attempt outside of acceptable console range. */
145 if (index
>= MAX_NR_HVC_CONSOLES
)
148 /* This console adapter was removed so it is not usable. */
149 if (vtermnos
[index
] < 0)
152 while (count
> 0 || i
> 0) {
153 if (count
> 0 && i
< sizeof(c
)) {
154 if (b
[n
] == '\n' && !donecr
) {
163 r
= cons_ops
[index
]->put_chars(vtermnos
[index
], c
, i
);
165 /* throw away chars on error */
176 static struct tty_driver
*hvc_console_device(struct console
*c
, int *index
)
178 if (vtermnos
[c
->index
] == -1)
185 static int __init
hvc_console_setup(struct console
*co
, char *options
)
187 if (co
->index
< 0 || co
->index
>= MAX_NR_HVC_CONSOLES
)
190 if (vtermnos
[co
->index
] == -1)
196 static struct console hvc_con_driver
= {
198 .write
= hvc_console_print
,
199 .device
= hvc_console_device
,
200 .setup
= hvc_console_setup
,
201 .flags
= CON_PRINTBUFFER
,
206 * Early console initialization. Precedes driver initialization.
208 * (1) we are first, and the user specified another driver
209 * -- index will remain -1
210 * (2) we are first and the user specified no driver
211 * -- index will be set to 0, then we will fail setup.
212 * (3) we are first and the user specified our driver
213 * -- index will be set to user specified driver, and we will fail
214 * (4) we are after driver, and this initcall will register us
215 * -- if the user didn't specify a driver then the console will match
217 * Note that for cases 2 and 3, we will match later when the io driver
218 * calls hvc_instantiate() and call register again.
220 static int __init
hvc_console_init(void)
222 register_console(&hvc_con_driver
);
225 console_initcall(hvc_console_init
);
227 /* callback when the kboject ref count reaches zero. */
228 static void destroy_hvc_struct(struct kref
*kref
)
230 struct hvc_struct
*hp
= container_of(kref
, struct hvc_struct
, kref
);
233 spin_lock(&hvc_structs_lock
);
235 spin_lock_irqsave(&hp
->lock
, flags
);
236 list_del(&(hp
->next
));
237 spin_unlock_irqrestore(&hp
->lock
, flags
);
239 spin_unlock(&hvc_structs_lock
);
245 * hvc_instantiate() is an early console discovery method which locates
246 * consoles * prior to the vio subsystem discovering them. Hotplugged
247 * vty adapters do NOT get an hvc_instantiate() callback since they
248 * appear after early console init.
250 int hvc_instantiate(uint32_t vtermno
, int index
, struct hv_ops
*ops
)
252 struct hvc_struct
*hp
;
254 if (index
< 0 || index
>= MAX_NR_HVC_CONSOLES
)
257 if (vtermnos
[index
] != -1)
260 /* make sure no no tty has been registered in this index */
261 hp
= hvc_get_by_index(index
);
263 kref_put(&hp
->kref
, destroy_hvc_struct
);
267 vtermnos
[index
] = vtermno
;
268 cons_ops
[index
] = ops
;
270 /* reserve all indices up to and including this index */
271 if (last_hvc
< index
)
274 /* if this index is what the user requested, then register
275 * now (setup won't fail at this point). It's ok to just
276 * call register again if previously .setup failed.
278 if (index
== hvc_con_driver
.index
)
279 register_console(&hvc_con_driver
);
283 EXPORT_SYMBOL_GPL(hvc_instantiate
);
285 /* Wake the sleeping khvcd */
289 wake_up_process(hvc_task
);
291 EXPORT_SYMBOL_GPL(hvc_kick
);
293 static void hvc_unthrottle(struct tty_struct
*tty
)
299 * The TTY interface won't be used until after the vio layer has exposed the vty
300 * adapter to the kernel.
302 static int hvc_open(struct tty_struct
*tty
, struct file
* filp
)
304 struct hvc_struct
*hp
;
308 /* Auto increments kref reference if found. */
309 if (!(hp
= hvc_get_by_index(tty
->index
)))
312 spin_lock_irqsave(&hp
->lock
, flags
);
313 /* Check and then increment for fast path open. */
314 if (hp
->count
++ > 0) {
315 spin_unlock_irqrestore(&hp
->lock
, flags
);
318 } /* else count == 0 */
320 tty
->driver_data
= hp
;
321 tty
->low_latency
= 1; /* Makes flushes to ldisc synchronous. */
325 spin_unlock_irqrestore(&hp
->lock
, flags
);
327 if (hp
->ops
->notifier_add
)
328 rc
= hp
->ops
->notifier_add(hp
, hp
->data
);
331 * If the notifier fails we return an error. The tty layer
332 * will call hvc_close() after a failed open but we don't want to clean
333 * up there so we'll clean up here and clear out the previously set
334 * tty fields and return the kref reference.
337 spin_lock_irqsave(&hp
->lock
, flags
);
339 spin_unlock_irqrestore(&hp
->lock
, flags
);
340 tty
->driver_data
= NULL
;
341 kref_put(&hp
->kref
, destroy_hvc_struct
);
342 printk(KERN_ERR
"hvc_open: request_irq failed with rc %d.\n", rc
);
344 /* Force wakeup of the polling thread */
350 static void hvc_close(struct tty_struct
*tty
, struct file
* filp
)
352 struct hvc_struct
*hp
;
355 if (tty_hung_up_p(filp
))
359 * No driver_data means that this close was issued after a failed
360 * hvc_open by the tty layer's release_dev() function and we can just
361 * exit cleanly because the kref reference wasn't made.
363 if (!tty
->driver_data
)
366 hp
= tty
->driver_data
;
367 spin_lock_irqsave(&hp
->lock
, flags
);
369 if (--hp
->count
== 0) {
370 /* We are done with the tty pointer now. */
372 spin_unlock_irqrestore(&hp
->lock
, flags
);
374 if (hp
->ops
->notifier_del
)
375 hp
->ops
->notifier_del(hp
, hp
->data
);
378 * Chain calls chars_in_buffer() and returns immediately if
379 * there is no buffered data otherwise sleeps on a wait queue
380 * waking periodically to check chars_in_buffer().
382 tty_wait_until_sent(tty
, HVC_CLOSE_WAIT
);
385 printk(KERN_ERR
"hvc_close %X: oops, count is %d\n",
386 hp
->vtermno
, hp
->count
);
387 spin_unlock_irqrestore(&hp
->lock
, flags
);
390 kref_put(&hp
->kref
, destroy_hvc_struct
);
393 static void hvc_hangup(struct tty_struct
*tty
)
395 struct hvc_struct
*hp
= tty
->driver_data
;
402 spin_lock_irqsave(&hp
->lock
, flags
);
405 * The N_TTY line discipline has problems such that in a close vs
406 * open->hangup case this can be called after the final close so prevent
407 * that from happening for now.
409 if (hp
->count
<= 0) {
410 spin_unlock_irqrestore(&hp
->lock
, flags
);
414 temp_open_count
= hp
->count
;
419 spin_unlock_irqrestore(&hp
->lock
, flags
);
421 if (hp
->ops
->notifier_del
)
422 hp
->ops
->notifier_del(hp
, hp
->data
);
424 while(temp_open_count
) {
426 kref_put(&hp
->kref
, destroy_hvc_struct
);
431 * Push buffered characters whether they were just recently buffered or waiting
432 * on a blocked hypervisor. Call this function with hp->lock held.
434 static void hvc_push(struct hvc_struct
*hp
)
438 n
= hp
->ops
->put_chars(hp
->vtermno
, hp
->outbuf
, hp
->n_outbuf
);
444 /* throw away output on error; this happens when
445 there is no session connected to the vterm. */
449 if (hp
->n_outbuf
> 0)
450 memmove(hp
->outbuf
, hp
->outbuf
+ n
, hp
->n_outbuf
);
455 static int hvc_write(struct tty_struct
*tty
, const unsigned char *buf
, int count
)
457 struct hvc_struct
*hp
= tty
->driver_data
;
459 int rsize
, written
= 0;
461 /* This write was probably executed during a tty close. */
468 spin_lock_irqsave(&hp
->lock
, flags
);
470 /* Push pending writes */
471 if (hp
->n_outbuf
> 0)
474 while (count
> 0 && (rsize
= hp
->outbuf_size
- hp
->n_outbuf
) > 0) {
477 memcpy(hp
->outbuf
+ hp
->n_outbuf
, buf
, rsize
);
480 hp
->n_outbuf
+= rsize
;
484 spin_unlock_irqrestore(&hp
->lock
, flags
);
487 * Racy, but harmless, kick thread if there is still pending data.
496 * This is actually a contract between the driver and the tty layer outlining
497 * how much write room the driver can guarantee will be sent OR BUFFERED. This
498 * driver MUST honor the return value.
500 static int hvc_write_room(struct tty_struct
*tty
)
502 struct hvc_struct
*hp
= tty
->driver_data
;
507 return hp
->outbuf_size
- hp
->n_outbuf
;
510 static int hvc_chars_in_buffer(struct tty_struct
*tty
)
512 struct hvc_struct
*hp
= tty
->driver_data
;
520 * timeout will vary between the MIN and MAX values defined here. By default
521 * and during console activity we will use a default MIN_TIMEOUT of 10. When
522 * the console is idle, we increase the timeout value on each pass through
523 * msleep until we reach the max. This may be noticeable as a brief (average
524 * one second) delay on the console before the console responds to input when
525 * there has been no input for some time.
527 #define MIN_TIMEOUT (10)
528 #define MAX_TIMEOUT (2000)
529 static u32 timeout
= MIN_TIMEOUT
;
531 #define HVC_POLL_READ 0x00000001
532 #define HVC_POLL_WRITE 0x00000002
534 int hvc_poll(struct hvc_struct
*hp
)
536 struct tty_struct
*tty
;
537 int i
, n
, poll_mask
= 0;
538 char buf
[N_INBUF
] __ALIGNED__
;
542 spin_lock_irqsave(&hp
->lock
, flags
);
544 /* Push pending writes */
545 if (hp
->n_outbuf
> 0)
548 /* Reschedule us if still some write pending */
549 if (hp
->n_outbuf
> 0)
550 poll_mask
|= HVC_POLL_WRITE
;
552 /* No tty attached, just skip */
557 /* Now check if we can get data (are we throttled ?) */
558 if (test_bit(TTY_THROTTLED
, &tty
->flags
))
561 /* If we aren't notifier driven and aren't throttled, we always
562 * request a reschedule
564 if (!hp
->irq_requested
)
565 poll_mask
|= HVC_POLL_READ
;
567 /* Read data if any */
569 int count
= tty_buffer_request_room(tty
, N_INBUF
);
571 /* If flip is full, just reschedule a later read */
573 poll_mask
|= HVC_POLL_READ
;
577 n
= hp
->ops
->get_chars(hp
->vtermno
, buf
, count
);
579 /* Hangup the tty when disconnected from host */
581 spin_unlock_irqrestore(&hp
->lock
, flags
);
583 spin_lock_irqsave(&hp
->lock
, flags
);
584 } else if ( n
== -EAGAIN
) {
586 * Some back-ends can only ensure a certain min
587 * num of bytes read, which may be > 'count'.
588 * Let the tty clear the flip buff to make room.
590 poll_mask
|= HVC_POLL_READ
;
594 for (i
= 0; i
< n
; ++i
) {
595 #ifdef CONFIG_MAGIC_SYSRQ
596 if (hp
->index
== hvc_con_driver
.index
) {
597 /* Handle the SysRq Hack */
598 /* XXX should support a sequence */
599 if (buf
[i
] == '\x0f') { /* ^O */
602 } else if (sysrq_pressed
) {
603 handle_sysrq(buf
[i
], tty
);
608 #endif /* CONFIG_MAGIC_SYSRQ */
609 tty_insert_flip_char(tty
, buf
[i
], 0);
615 /* Wakeup write queue if necessary */
621 spin_unlock_irqrestore(&hp
->lock
, flags
);
624 /* Activity is occurring, so reset the polling backoff value to
625 a minimum for performance. */
626 timeout
= MIN_TIMEOUT
;
628 tty_flip_buffer_push(tty
);
633 EXPORT_SYMBOL_GPL(hvc_poll
);
636 * This kthread is either polling or interrupt driven. This is determined by
637 * calling hvc_poll() who determines whether a console adapter support
640 static int khvcd(void *unused
)
643 struct hvc_struct
*hp
;
646 __set_current_state(TASK_RUNNING
);
652 if (!cpus_are_in_xmon()) {
653 spin_lock(&hvc_structs_lock
);
654 list_for_each_entry(hp
, &hvc_structs
, next
) {
655 poll_mask
|= hvc_poll(hp
);
657 spin_unlock(&hvc_structs_lock
);
659 poll_mask
|= HVC_POLL_READ
;
662 if (poll_mask
& HVC_POLL_WRITE
) {
666 set_current_state(TASK_INTERRUPTIBLE
);
671 if (timeout
< MAX_TIMEOUT
)
672 timeout
+= (timeout
>> 6) + 1;
674 msleep_interruptible(timeout
);
677 __set_current_state(TASK_RUNNING
);
678 } while (!kthread_should_stop());
683 static const struct tty_operations hvc_ops
= {
687 .hangup
= hvc_hangup
,
688 .unthrottle
= hvc_unthrottle
,
689 .write_room
= hvc_write_room
,
690 .chars_in_buffer
= hvc_chars_in_buffer
,
693 struct hvc_struct __devinit
*hvc_alloc(uint32_t vtermno
, int data
,
694 struct hv_ops
*ops
, int outbuf_size
)
696 struct hvc_struct
*hp
;
699 /* We wait until a driver actually comes along */
701 int err
= hvc_init();
706 hp
= kmalloc(ALIGN(sizeof(*hp
), sizeof(long)) + outbuf_size
,
709 return ERR_PTR(-ENOMEM
);
711 memset(hp
, 0x00, sizeof(*hp
));
713 hp
->vtermno
= vtermno
;
716 hp
->outbuf_size
= outbuf_size
;
717 hp
->outbuf
= &((char *)hp
)[ALIGN(sizeof(*hp
), sizeof(long))];
719 kref_init(&hp
->kref
);
721 spin_lock_init(&hp
->lock
);
722 spin_lock(&hvc_structs_lock
);
726 * see if this vterm id matches one registered for console.
728 for (i
=0; i
< MAX_NR_HVC_CONSOLES
; i
++)
729 if (vtermnos
[i
] == hp
->vtermno
&&
730 cons_ops
[i
] == hp
->ops
)
733 /* no matching slot, just use a counter */
734 if (i
>= MAX_NR_HVC_CONSOLES
)
739 list_add_tail(&(hp
->next
), &hvc_structs
);
740 spin_unlock(&hvc_structs_lock
);
744 EXPORT_SYMBOL_GPL(hvc_alloc
);
746 int __devexit
hvc_remove(struct hvc_struct
*hp
)
749 struct tty_struct
*tty
;
751 spin_lock_irqsave(&hp
->lock
, flags
);
754 if (hp
->index
< MAX_NR_HVC_CONSOLES
)
755 vtermnos
[hp
->index
] = -1;
757 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
759 spin_unlock_irqrestore(&hp
->lock
, flags
);
762 * We 'put' the instance that was grabbed when the kref instance
763 * was initialized using kref_init(). Let the last holder of this
764 * kref cause it to be removed, which will probably be the tty_hangup
767 kref_put(&hp
->kref
, destroy_hvc_struct
);
770 * This function call will auto chain call hvc_hangup. The tty should
771 * always be valid at this time unless a simultaneous tty close already
772 * cleaned up the hvc_struct.
779 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
780 static int hvc_init(void)
782 struct tty_driver
*drv
;
785 /* We need more than hvc_count adapters due to hotplug additions. */
786 drv
= alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS
);
792 drv
->owner
= THIS_MODULE
;
793 drv
->driver_name
= "hvc";
795 drv
->major
= HVC_MAJOR
;
796 drv
->minor_start
= HVC_MINOR
;
797 drv
->type
= TTY_DRIVER_TYPE_SYSTEM
;
798 drv
->init_termios
= tty_std_termios
;
799 drv
->flags
= TTY_DRIVER_REAL_RAW
;
800 tty_set_operations(drv
, &hvc_ops
);
802 /* Always start the kthread because there can be hotplug vty adapters
804 hvc_task
= kthread_run(khvcd
, NULL
, "khvcd");
805 if (IS_ERR(hvc_task
)) {
806 printk(KERN_ERR
"Couldn't create kthread for console.\n");
807 err
= PTR_ERR(hvc_task
);
811 err
= tty_register_driver(drv
);
813 printk(KERN_ERR
"Couldn't register hvc console driver\n");
817 /* FIXME: This mb() seems completely random. Remove it. */
823 kthread_stop(hvc_task
);
831 /* This isn't particularly necessary due to this being a console driver
832 * but it is nice to be thorough.
834 static void __exit
hvc_exit(void)
837 kthread_stop(hvc_task
);
839 tty_unregister_driver(hvc_driver
);
840 /* return tty_struct instances allocated in hvc_init(). */
841 put_tty_driver(hvc_driver
);
842 unregister_console(&hvc_con_driver
);
845 module_exit(hvc_exit
);