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/kobject.h>
31 #include <linux/kthread.h>
32 #include <linux/list.h>
33 #include <linux/module.h>
34 #include <linux/major.h>
35 #include <linux/sysrq.h>
36 #include <linux/tty.h>
37 #include <linux/tty_flip.h>
38 #include <linux/sched.h>
39 #include <linux/spinlock.h>
40 #include <linux/delay.h>
41 #include <linux/freezer.h>
43 #include <asm/uaccess.h>
45 #include "hvc_console.h"
51 * Wait this long per iteration while trying to push buffered data to the
52 * hypervisor before allowing the tty to complete a close operation.
54 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57 * These sizes are most efficient for vio, because they are the
58 * native transfer size. We could make them selectable in the
59 * future to better deal with backends that want other buffer sizes.
64 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
66 static struct tty_driver
*hvc_driver
;
67 static struct task_struct
*hvc_task
;
69 /* Picks up late kicks after list walk but before schedule() */
70 static int hvc_kicked
;
72 #ifdef CONFIG_MAGIC_SYSRQ
73 static int sysrq_pressed
;
79 struct tty_struct
*tty
;
89 struct list_head next
;
90 struct kobject kobj
; /* ref count & hvc_struct lifetime */
93 /* dynamic list of hvc_struct instances */
94 static struct list_head hvc_structs
= LIST_HEAD_INIT(hvc_structs
);
97 * Protect the list of hvc_struct instances from inserts and removals during
100 static DEFINE_SPINLOCK(hvc_structs_lock
);
103 * This value is used to assign a tty->index value to a hvc_struct based
104 * upon order of exposure via hvc_probe(), when we can not match it to
105 * a console candidate registered with hvc_instantiate().
107 static int last_hvc
= -1;
110 * Do not call this function with either the hvc_structs_lock or the hvc_struct
111 * lock held. If successful, this function increments the kobject reference
112 * count against the target hvc_struct so it should be released when finished.
114 static struct hvc_struct
*hvc_get_by_index(int index
)
116 struct hvc_struct
*hp
;
119 spin_lock(&hvc_structs_lock
);
121 list_for_each_entry(hp
, &hvc_structs
, next
) {
122 spin_lock_irqsave(&hp
->lock
, flags
);
123 if (hp
->index
== index
) {
124 kobject_get(&hp
->kobj
);
125 spin_unlock_irqrestore(&hp
->lock
, flags
);
126 spin_unlock(&hvc_structs_lock
);
129 spin_unlock_irqrestore(&hp
->lock
, flags
);
133 spin_unlock(&hvc_structs_lock
);
139 * Initial console vtermnos for console API usage prior to full console
140 * initialization. Any vty adapter outside this range will not have usable
141 * console interfaces but can still be used as a tty device. This has to be
142 * static because kmalloc will not work during early console init.
144 static struct hv_ops
*cons_ops
[MAX_NR_HVC_CONSOLES
];
145 static uint32_t vtermnos
[MAX_NR_HVC_CONSOLES
] =
146 {[0 ... MAX_NR_HVC_CONSOLES
- 1] = -1};
149 * Console APIs, NOT TTY. These APIs are available immediately when
150 * hvc_console_setup() finds adapters.
153 static void hvc_console_print(struct console
*co
, const char *b
,
156 char c
[N_OUTBUF
] __ALIGNED__
;
157 unsigned i
= 0, n
= 0;
158 int r
, donecr
= 0, index
= co
->index
;
160 /* Console access attempt outside of acceptable console range. */
161 if (index
>= MAX_NR_HVC_CONSOLES
)
164 /* This console adapter was removed so it is not usable. */
165 if (vtermnos
[index
] < 0)
168 while (count
> 0 || i
> 0) {
169 if (count
> 0 && i
< sizeof(c
)) {
170 if (b
[n
] == '\n' && !donecr
) {
179 r
= cons_ops
[index
]->put_chars(vtermnos
[index
], c
, i
);
181 /* throw away chars on error */
192 static struct tty_driver
*hvc_console_device(struct console
*c
, int *index
)
194 if (vtermnos
[c
->index
] == -1)
201 static int __init
hvc_console_setup(struct console
*co
, char *options
)
203 if (co
->index
< 0 || co
->index
>= MAX_NR_HVC_CONSOLES
)
206 if (vtermnos
[co
->index
] == -1)
212 static struct console hvc_con_driver
= {
214 .write
= hvc_console_print
,
215 .device
= hvc_console_device
,
216 .setup
= hvc_console_setup
,
217 .flags
= CON_PRINTBUFFER
,
222 * Early console initialization. Precedes driver initialization.
224 * (1) we are first, and the user specified another driver
225 * -- index will remain -1
226 * (2) we are first and the user specified no driver
227 * -- index will be set to 0, then we will fail setup.
228 * (3) we are first and the user specified our driver
229 * -- index will be set to user specified driver, and we will fail
230 * (4) we are after driver, and this initcall will register us
231 * -- if the user didn't specify a driver then the console will match
233 * Note that for cases 2 and 3, we will match later when the io driver
234 * calls hvc_instantiate() and call register again.
236 static int __init
hvc_console_init(void)
238 register_console(&hvc_con_driver
);
241 console_initcall(hvc_console_init
);
244 * hvc_instantiate() is an early console discovery method which locates
245 * consoles * prior to the vio subsystem discovering them. Hotplugged
246 * vty adapters do NOT get an hvc_instantiate() callback since they
247 * appear after early console init.
249 int hvc_instantiate(uint32_t vtermno
, int index
, struct hv_ops
*ops
)
251 struct hvc_struct
*hp
;
253 if (index
< 0 || index
>= MAX_NR_HVC_CONSOLES
)
256 if (vtermnos
[index
] != -1)
259 /* make sure no no tty has been registered in this index */
260 hp
= hvc_get_by_index(index
);
262 kobject_put(&hp
->kobj
);
266 vtermnos
[index
] = vtermno
;
267 cons_ops
[index
] = ops
;
269 /* reserve all indices up to and including this index */
270 if (last_hvc
< index
)
273 /* if this index is what the user requested, then register
274 * now (setup won't fail at this point). It's ok to just
275 * call register again if previously .setup failed.
277 if (index
== hvc_con_driver
.index
)
278 register_console(&hvc_con_driver
);
283 /* Wake the sleeping khvcd */
284 static void hvc_kick(void)
287 wake_up_process(hvc_task
);
290 static int hvc_poll(struct hvc_struct
*hp
);
293 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
294 * In this case the console is poll driven.
296 static irqreturn_t
hvc_handle_interrupt(int irq
, void *dev_instance
)
298 /* if hvc_poll request a repoll, then kick the hvcd thread */
299 if (hvc_poll(dev_instance
))
304 static void hvc_unthrottle(struct tty_struct
*tty
)
310 * The TTY interface won't be used until after the vio layer has exposed the vty
311 * adapter to the kernel.
313 static int hvc_open(struct tty_struct
*tty
, struct file
* filp
)
315 struct hvc_struct
*hp
;
319 struct kobject
*kobjp
;
321 /* Auto increments kobject reference if found. */
322 if (!(hp
= hvc_get_by_index(tty
->index
)))
325 spin_lock_irqsave(&hp
->lock
, flags
);
326 /* Check and then increment for fast path open. */
327 if (hp
->count
++ > 0) {
328 spin_unlock_irqrestore(&hp
->lock
, flags
);
331 } /* else count == 0 */
333 tty
->driver_data
= hp
;
334 tty
->low_latency
= 1; /* Makes flushes to ldisc synchronous. */
337 /* Save for request_irq outside of spin_lock. */
340 hp
->irq_requested
= 1;
344 spin_unlock_irqrestore(&hp
->lock
, flags
);
345 /* check error, fallback to non-irq */
347 rc
= request_irq(irq
, hvc_handle_interrupt
, IRQF_DISABLED
, "hvc_console", hp
);
350 * If the request_irq() fails and we return an error. The tty layer
351 * will call hvc_close() after a failed open but we don't want to clean
352 * up there so we'll clean up here and clear out the previously set
353 * tty fields and return the kobject reference.
356 spin_lock_irqsave(&hp
->lock
, flags
);
358 hp
->irq_requested
= 0;
359 spin_unlock_irqrestore(&hp
->lock
, flags
);
360 tty
->driver_data
= NULL
;
362 printk(KERN_ERR
"hvc_open: request_irq failed with rc %d.\n", rc
);
364 /* Force wakeup of the polling thread */
370 static void hvc_close(struct tty_struct
*tty
, struct file
* filp
)
372 struct hvc_struct
*hp
;
373 struct kobject
*kobjp
;
377 if (tty_hung_up_p(filp
))
381 * No driver_data means that this close was issued after a failed
382 * hvc_open by the tty layer's release_dev() function and we can just
383 * exit cleanly because the kobject reference wasn't made.
385 if (!tty
->driver_data
)
388 hp
= tty
->driver_data
;
389 spin_lock_irqsave(&hp
->lock
, flags
);
392 if (--hp
->count
== 0) {
393 if (hp
->irq_requested
)
395 hp
->irq_requested
= 0;
397 /* We are done with the tty pointer now. */
399 spin_unlock_irqrestore(&hp
->lock
, flags
);
402 * Chain calls chars_in_buffer() and returns immediately if
403 * there is no buffered data otherwise sleeps on a wait queue
404 * waking periodically to check chars_in_buffer().
406 tty_wait_until_sent(tty
, HVC_CLOSE_WAIT
);
413 printk(KERN_ERR
"hvc_close %X: oops, count is %d\n",
414 hp
->vtermno
, hp
->count
);
415 spin_unlock_irqrestore(&hp
->lock
, flags
);
421 static void hvc_hangup(struct tty_struct
*tty
)
423 struct hvc_struct
*hp
= tty
->driver_data
;
427 struct kobject
*kobjp
;
432 spin_lock_irqsave(&hp
->lock
, flags
);
435 * The N_TTY line discipline has problems such that in a close vs
436 * open->hangup case this can be called after the final close so prevent
437 * that from happening for now.
439 if (hp
->count
<= 0) {
440 spin_unlock_irqrestore(&hp
->lock
, flags
);
445 temp_open_count
= hp
->count
;
449 if (hp
->irq_requested
)
450 /* Saved for use outside of spin_lock. */
452 hp
->irq_requested
= 0;
453 spin_unlock_irqrestore(&hp
->lock
, flags
);
456 while(temp_open_count
) {
463 * Push buffered characters whether they were just recently buffered or waiting
464 * on a blocked hypervisor. Call this function with hp->lock held.
466 static void hvc_push(struct hvc_struct
*hp
)
470 n
= hp
->ops
->put_chars(hp
->vtermno
, hp
->outbuf
, hp
->n_outbuf
);
476 /* throw away output on error; this happens when
477 there is no session connected to the vterm. */
481 if (hp
->n_outbuf
> 0)
482 memmove(hp
->outbuf
, hp
->outbuf
+ n
, hp
->n_outbuf
);
487 static int hvc_write(struct tty_struct
*tty
, const unsigned char *buf
, int count
)
489 struct hvc_struct
*hp
= tty
->driver_data
;
491 int rsize
, written
= 0;
493 /* This write was probably executed during a tty close. */
500 spin_lock_irqsave(&hp
->lock
, flags
);
502 /* Push pending writes */
503 if (hp
->n_outbuf
> 0)
506 while (count
> 0 && (rsize
= hp
->outbuf_size
- hp
->n_outbuf
) > 0) {
509 memcpy(hp
->outbuf
+ hp
->n_outbuf
, buf
, rsize
);
512 hp
->n_outbuf
+= rsize
;
516 spin_unlock_irqrestore(&hp
->lock
, flags
);
519 * Racy, but harmless, kick thread if there is still pending data.
528 * This is actually a contract between the driver and the tty layer outlining
529 * how much write room the driver can guarantee will be sent OR BUFFERED. This
530 * driver MUST honor the return value.
532 static int hvc_write_room(struct tty_struct
*tty
)
534 struct hvc_struct
*hp
= tty
->driver_data
;
539 return hp
->outbuf_size
- hp
->n_outbuf
;
542 static int hvc_chars_in_buffer(struct tty_struct
*tty
)
544 struct hvc_struct
*hp
= tty
->driver_data
;
552 * timeout will vary between the MIN and MAX values defined here. By default
553 * and during console activity we will use a default MIN_TIMEOUT of 10. When
554 * the console is idle, we increase the timeout value on each pass through
555 * msleep until we reach the max. This may be noticeable as a brief (average
556 * one second) delay on the console before the console responds to input when
557 * there has been no input for some time.
559 #define MIN_TIMEOUT (10)
560 #define MAX_TIMEOUT (2000)
561 static u32 timeout
= MIN_TIMEOUT
;
563 #define HVC_POLL_READ 0x00000001
564 #define HVC_POLL_WRITE 0x00000002
566 static int hvc_poll(struct hvc_struct
*hp
)
568 struct tty_struct
*tty
;
569 int i
, n
, poll_mask
= 0;
570 char buf
[N_INBUF
] __ALIGNED__
;
574 spin_lock_irqsave(&hp
->lock
, flags
);
576 /* Push pending writes */
577 if (hp
->n_outbuf
> 0)
580 /* Reschedule us if still some write pending */
581 if (hp
->n_outbuf
> 0)
582 poll_mask
|= HVC_POLL_WRITE
;
584 /* No tty attached, just skip */
589 /* Now check if we can get data (are we throttled ?) */
590 if (test_bit(TTY_THROTTLED
, &tty
->flags
))
593 /* If we aren't interrupt driven and aren't throttled, we always
594 * request a reschedule
597 poll_mask
|= HVC_POLL_READ
;
599 /* Read data if any */
601 int count
= tty_buffer_request_room(tty
, N_INBUF
);
603 /* If flip is full, just reschedule a later read */
605 poll_mask
|= HVC_POLL_READ
;
609 n
= hp
->ops
->get_chars(hp
->vtermno
, buf
, count
);
611 /* Hangup the tty when disconnected from host */
613 spin_unlock_irqrestore(&hp
->lock
, flags
);
615 spin_lock_irqsave(&hp
->lock
, flags
);
616 } else if ( n
== -EAGAIN
) {
618 * Some back-ends can only ensure a certain min
619 * num of bytes read, which may be > 'count'.
620 * Let the tty clear the flip buff to make room.
622 poll_mask
|= HVC_POLL_READ
;
626 for (i
= 0; i
< n
; ++i
) {
627 #ifdef CONFIG_MAGIC_SYSRQ
628 if (hp
->index
== hvc_con_driver
.index
) {
629 /* Handle the SysRq Hack */
630 /* XXX should support a sequence */
631 if (buf
[i
] == '\x0f') { /* ^O */
634 } else if (sysrq_pressed
) {
635 handle_sysrq(buf
[i
], tty
);
640 #endif /* CONFIG_MAGIC_SYSRQ */
641 tty_insert_flip_char(tty
, buf
[i
], 0);
647 /* Wakeup write queue if necessary */
653 spin_unlock_irqrestore(&hp
->lock
, flags
);
656 /* Activity is occurring, so reset the polling backoff value to
657 a minimum for performance. */
658 timeout
= MIN_TIMEOUT
;
660 tty_flip_buffer_push(tty
);
666 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
667 extern cpumask_t cpus_in_xmon
;
669 static const cpumask_t cpus_in_xmon
= CPU_MASK_NONE
;
673 * This kthread is either polling or interrupt driven. This is determined by
674 * calling hvc_poll() who determines whether a console adapter support
677 static int khvcd(void *unused
)
680 struct hvc_struct
*hp
;
683 __set_current_state(TASK_RUNNING
);
689 if (cpus_empty(cpus_in_xmon
)) {
690 spin_lock(&hvc_structs_lock
);
691 list_for_each_entry(hp
, &hvc_structs
, next
) {
692 poll_mask
|= hvc_poll(hp
);
694 spin_unlock(&hvc_structs_lock
);
696 poll_mask
|= HVC_POLL_READ
;
699 if (poll_mask
& HVC_POLL_WRITE
) {
703 set_current_state(TASK_INTERRUPTIBLE
);
708 if (timeout
< MAX_TIMEOUT
)
709 timeout
+= (timeout
>> 6) + 1;
711 msleep_interruptible(timeout
);
714 __set_current_state(TASK_RUNNING
);
715 } while (!kthread_should_stop());
720 static const struct tty_operations hvc_ops
= {
724 .hangup
= hvc_hangup
,
725 .unthrottle
= hvc_unthrottle
,
726 .write_room
= hvc_write_room
,
727 .chars_in_buffer
= hvc_chars_in_buffer
,
730 /* callback when the kboject ref count reaches zero. */
731 static void destroy_hvc_struct(struct kobject
*kobj
)
733 struct hvc_struct
*hp
= container_of(kobj
, struct hvc_struct
, kobj
);
736 spin_lock(&hvc_structs_lock
);
738 spin_lock_irqsave(&hp
->lock
, flags
);
739 list_del(&(hp
->next
));
740 spin_unlock_irqrestore(&hp
->lock
, flags
);
742 spin_unlock(&hvc_structs_lock
);
747 static struct kobj_type hvc_kobj_type
= {
748 .release
= destroy_hvc_struct
,
751 struct hvc_struct __devinit
*hvc_alloc(uint32_t vtermno
, int irq
,
752 struct hv_ops
*ops
, int outbuf_size
)
754 struct hvc_struct
*hp
;
757 hp
= kmalloc(ALIGN(sizeof(*hp
), sizeof(long)) + outbuf_size
,
760 return ERR_PTR(-ENOMEM
);
762 memset(hp
, 0x00, sizeof(*hp
));
764 hp
->vtermno
= vtermno
;
767 hp
->outbuf_size
= outbuf_size
;
768 hp
->outbuf
= &((char *)hp
)[ALIGN(sizeof(*hp
), sizeof(long))];
770 kobject_init(&hp
->kobj
);
771 hp
->kobj
.ktype
= &hvc_kobj_type
;
773 spin_lock_init(&hp
->lock
);
774 spin_lock(&hvc_structs_lock
);
778 * see if this vterm id matches one registered for console.
780 for (i
=0; i
< MAX_NR_HVC_CONSOLES
; i
++)
781 if (vtermnos
[i
] == hp
->vtermno
&&
782 cons_ops
[i
] == hp
->ops
)
785 /* no matching slot, just use a counter */
786 if (i
>= MAX_NR_HVC_CONSOLES
)
791 list_add_tail(&(hp
->next
), &hvc_structs
);
792 spin_unlock(&hvc_structs_lock
);
797 int __devexit
hvc_remove(struct hvc_struct
*hp
)
800 struct kobject
*kobjp
;
801 struct tty_struct
*tty
;
803 spin_lock_irqsave(&hp
->lock
, flags
);
807 if (hp
->index
< MAX_NR_HVC_CONSOLES
)
808 vtermnos
[hp
->index
] = -1;
810 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
812 spin_unlock_irqrestore(&hp
->lock
, flags
);
815 * We 'put' the instance that was grabbed when the kobject instance
816 * was initialized using kobject_init(). Let the last holder of this
817 * kobject cause it to be removed, which will probably be the tty_hangup
823 * This function call will auto chain call hvc_hangup. The tty should
824 * always be valid at this time unless a simultaneous tty close already
825 * cleaned up the hvc_struct.
832 /* Driver initialization. Follow console initialization. This is where the TTY
833 * interfaces start to become available. */
834 static int __init
hvc_init(void)
836 struct tty_driver
*drv
;
838 /* We need more than hvc_count adapters due to hotplug additions. */
839 drv
= alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS
);
843 drv
->owner
= THIS_MODULE
;
844 drv
->driver_name
= "hvc";
846 drv
->major
= HVC_MAJOR
;
847 drv
->minor_start
= HVC_MINOR
;
848 drv
->type
= TTY_DRIVER_TYPE_SYSTEM
;
849 drv
->init_termios
= tty_std_termios
;
850 drv
->flags
= TTY_DRIVER_REAL_RAW
;
851 tty_set_operations(drv
, &hvc_ops
);
853 /* Always start the kthread because there can be hotplug vty adapters
855 hvc_task
= kthread_run(khvcd
, NULL
, "khvcd");
856 if (IS_ERR(hvc_task
)) {
857 panic("Couldn't create kthread for console.\n");
862 if (tty_register_driver(drv
))
863 panic("Couldn't register hvc console driver\n");
869 module_init(hvc_init
);
871 /* This isn't particularly necessary due to this being a console driver
872 * but it is nice to be thorough.
874 static void __exit
hvc_exit(void)
876 kthread_stop(hvc_task
);
878 tty_unregister_driver(hvc_driver
);
879 /* return tty_struct instances allocated in hvc_init(). */
880 put_tty_driver(hvc_driver
);
881 unregister_console(&hvc_con_driver
);
883 module_exit(hvc_exit
);