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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - drivers/char/hvc_console.c
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>
42 #include <asm/uaccess.h>
44 #include "hvc_console.h"
52 * Wait this long per iteration while trying to push buffered data to the
53 * hypervisor before allowing the tty to complete a close operation.
55 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
58 * These sizes are most efficient for vio, because they are the
59 * native transfer size. We could make them selectable in the
60 * future to better deal with backends that want other buffer sizes.
65 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
67 static struct tty_driver
*hvc_driver
;
68 static struct task_struct
*hvc_task
;
70 /* Picks up late kicks after list walk but before schedule() */
71 static int hvc_kicked
;
73 #ifdef CONFIG_MAGIC_SYSRQ
74 static int sysrq_pressed
;
80 struct tty_struct
*tty
;
83 char outbuf
[N_OUTBUF
] __ALIGNED__
;
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 canidate registered with hvc_instantiate().
107 static int last_hvc
= -1;
110 * Do not call this function with either the hvc_strucst_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 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 void hvc_console_print(struct console
*co
, const char *b
, unsigned count
)
155 char c
[N_OUTBUF
] __ALIGNED__
;
156 unsigned i
= 0, n
= 0;
157 int r
, donecr
= 0, index
= co
->index
;
159 /* Console access attempt outside of acceptable console range. */
160 if (index
>= MAX_NR_HVC_CONSOLES
)
163 /* This console adapter was removed so it is not useable. */
164 if (vtermnos
[index
] < 0)
167 while (count
> 0 || i
> 0) {
168 if (count
> 0 && i
< sizeof(c
)) {
169 if (b
[n
] == '\n' && !donecr
) {
178 r
= cons_ops
[index
]->put_chars(vtermnos
[index
], c
, i
);
180 /* throw away chars on error */
191 static struct tty_driver
*hvc_console_device(struct console
*c
, int *index
)
193 if (vtermnos
[c
->index
] == -1)
200 static int __init
hvc_console_setup(struct console
*co
, char *options
)
202 if (co
->index
< 0 || co
->index
>= MAX_NR_HVC_CONSOLES
)
205 if (vtermnos
[co
->index
] == -1)
211 struct console hvc_con_driver
= {
213 .write
= hvc_console_print
,
214 .device
= hvc_console_device
,
215 .setup
= hvc_console_setup
,
216 .flags
= CON_PRINTBUFFER
,
221 * Early console initialization. Preceeds driver initialization.
223 * (1) we are first, and the user specified another driver
224 * -- index will remain -1
225 * (2) we are first and the user specified no driver
226 * -- index will be set to 0, then we will fail setup.
227 * (3) we are first and the user specified our driver
228 * -- index will be set to user specified driver, and we will fail
229 * (4) we are after driver, and this initcall will register us
230 * -- if the user didn't specify a driver then the console will match
232 * Note that for cases 2 and 3, we will match later when the io driver
233 * calls hvc_instantiate() and call register again.
235 static int __init
hvc_console_init(void)
237 register_console(&hvc_con_driver
);
240 console_initcall(hvc_console_init
);
243 * hvc_instantiate() is an early console discovery method which locates
244 * consoles * prior to the vio subsystem discovering them. Hotplugged
245 * vty adapters do NOT get an hvc_instantiate() callback since they
246 * appear after early console init.
248 int hvc_instantiate(uint32_t vtermno
, int index
, struct hv_ops
*ops
)
250 struct hvc_struct
*hp
;
252 if (index
< 0 || index
>= MAX_NR_HVC_CONSOLES
)
255 if (vtermnos
[index
] != -1)
258 /* make sure no no tty has been registerd in this index */
259 hp
= hvc_get_by_index(index
);
261 kobject_put(&hp
->kobj
);
265 vtermnos
[index
] = vtermno
;
266 cons_ops
[index
] = ops
;
268 /* reserve all indices upto and including this index */
269 if (last_hvc
< index
)
272 /* if this index is what the user requested, then register
273 * now (setup won't fail at this point). It's ok to just
274 * call register again if previously .setup failed.
276 if (index
== hvc_con_driver
.index
)
277 register_console(&hvc_con_driver
);
281 EXPORT_SYMBOL(hvc_instantiate
);
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
, struct pt_regs
*regs
)
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
))) {
323 printk(KERN_WARNING
"hvc_console: tty open failed, no vty associated with tty.\n");
327 spin_lock_irqsave(&hp
->lock
, flags
);
328 /* Check and then increment for fast path open. */
329 if (hp
->count
++ > 0) {
330 spin_unlock_irqrestore(&hp
->lock
, flags
);
333 } /* else count == 0 */
335 tty
->driver_data
= hp
;
336 tty
->low_latency
= 1; /* Makes flushes to ldisc synchronous. */
339 /* Save for request_irq outside of spin_lock. */
342 hp
->irq_requested
= 1;
346 spin_unlock_irqrestore(&hp
->lock
, flags
);
347 /* check error, fallback to non-irq */
349 rc
= request_irq(irq
, hvc_handle_interrupt
, SA_INTERRUPT
, "hvc_console", hp
);
352 * If the request_irq() fails and we return an error. The tty layer
353 * will call hvc_close() after a failed open but we don't want to clean
354 * up there so we'll clean up here and clear out the previously set
355 * tty fields and return the kobject reference.
358 spin_lock_irqsave(&hp
->lock
, flags
);
360 hp
->irq_requested
= 0;
361 spin_unlock_irqrestore(&hp
->lock
, flags
);
362 tty
->driver_data
= NULL
;
364 printk(KERN_ERR
"hvc_open: request_irq failed with rc %d.\n", rc
);
366 /* Force wakeup of the polling thread */
372 static void hvc_close(struct tty_struct
*tty
, struct file
* filp
)
374 struct hvc_struct
*hp
;
375 struct kobject
*kobjp
;
379 if (tty_hung_up_p(filp
))
383 * No driver_data means that this close was issued after a failed
384 * hvc_open by the tty layer's release_dev() function and we can just
385 * exit cleanly because the kobject reference wasn't made.
387 if (!tty
->driver_data
)
390 hp
= tty
->driver_data
;
391 spin_lock_irqsave(&hp
->lock
, flags
);
394 if (--hp
->count
== 0) {
395 if (hp
->irq_requested
)
397 hp
->irq_requested
= 0;
399 /* We are done with the tty pointer now. */
401 spin_unlock_irqrestore(&hp
->lock
, flags
);
404 * Chain calls chars_in_buffer() and returns immediately if
405 * there is no buffered data otherwise sleeps on a wait queue
406 * waking periodically to check chars_in_buffer().
408 tty_wait_until_sent(tty
, HVC_CLOSE_WAIT
);
415 printk(KERN_ERR
"hvc_close %X: oops, count is %d\n",
416 hp
->vtermno
, hp
->count
);
417 spin_unlock_irqrestore(&hp
->lock
, flags
);
423 static void hvc_hangup(struct tty_struct
*tty
)
425 struct hvc_struct
*hp
= tty
->driver_data
;
429 struct kobject
*kobjp
;
434 spin_lock_irqsave(&hp
->lock
, flags
);
437 * The N_TTY line discipline has problems such that in a close vs
438 * open->hangup case this can be called after the final close so prevent
439 * that from happening for now.
441 if (hp
->count
<= 0) {
442 spin_unlock_irqrestore(&hp
->lock
, flags
);
447 temp_open_count
= hp
->count
;
451 if (hp
->irq_requested
)
452 /* Saved for use outside of spin_lock. */
454 hp
->irq_requested
= 0;
455 spin_unlock_irqrestore(&hp
->lock
, flags
);
458 while(temp_open_count
) {
465 * Push buffered characters whether they were just recently buffered or waiting
466 * on a blocked hypervisor. Call this function with hp->lock held.
468 static void hvc_push(struct hvc_struct
*hp
)
472 n
= hp
->ops
->put_chars(hp
->vtermno
, hp
->outbuf
, hp
->n_outbuf
);
478 /* throw away output on error; this happens when
479 there is no session connected to the vterm. */
483 if (hp
->n_outbuf
> 0)
484 memmove(hp
->outbuf
, hp
->outbuf
+ n
, hp
->n_outbuf
);
489 static int hvc_write(struct tty_struct
*tty
, const unsigned char *buf
, int count
)
491 struct hvc_struct
*hp
= tty
->driver_data
;
493 int rsize
, written
= 0;
495 /* This write was probably executed during a tty close. */
502 spin_lock_irqsave(&hp
->lock
, flags
);
504 /* Push pending writes */
505 if (hp
->n_outbuf
> 0)
508 while (count
> 0 && (rsize
= N_OUTBUF
- hp
->n_outbuf
) > 0) {
511 memcpy(hp
->outbuf
+ hp
->n_outbuf
, buf
, rsize
);
514 hp
->n_outbuf
+= rsize
;
518 spin_unlock_irqrestore(&hp
->lock
, flags
);
521 * Racy, but harmless, kick thread if there is still pending data.
530 * This is actually a contract between the driver and the tty layer outlining
531 * how much write room the driver can guarentee will be sent OR BUFFERED. This
532 * driver MUST honor the return value.
534 static int hvc_write_room(struct tty_struct
*tty
)
536 struct hvc_struct
*hp
= tty
->driver_data
;
541 return N_OUTBUF
- hp
->n_outbuf
;
544 static int hvc_chars_in_buffer(struct tty_struct
*tty
)
546 struct hvc_struct
*hp
= tty
->driver_data
;
553 #define HVC_POLL_READ 0x00000001
554 #define HVC_POLL_WRITE 0x00000002
556 static int hvc_poll(struct hvc_struct
*hp
)
558 struct tty_struct
*tty
;
559 int i
, n
, poll_mask
= 0;
560 char buf
[N_INBUF
] __ALIGNED__
;
564 spin_lock_irqsave(&hp
->lock
, flags
);
566 /* Push pending writes */
567 if (hp
->n_outbuf
> 0)
570 /* Reschedule us if still some write pending */
571 if (hp
->n_outbuf
> 0)
572 poll_mask
|= HVC_POLL_WRITE
;
574 /* No tty attached, just skip */
579 /* Now check if we can get data (are we throttled ?) */
580 if (test_bit(TTY_THROTTLED
, &tty
->flags
))
583 /* If we aren't interrupt driven and aren't throttled, we always
584 * request a reschedule
586 if (hp
->irq
== NO_IRQ
)
587 poll_mask
|= HVC_POLL_READ
;
589 /* Read data if any */
591 int count
= tty_buffer_request_room(tty
, N_INBUF
);
593 /* If flip is full, just reschedule a later read */
595 poll_mask
|= HVC_POLL_READ
;
599 n
= hp
->ops
->get_chars(hp
->vtermno
, buf
, count
);
601 /* Hangup the tty when disconnected from host */
603 spin_unlock_irqrestore(&hp
->lock
, flags
);
605 spin_lock_irqsave(&hp
->lock
, flags
);
606 } else if ( n
== -EAGAIN
) {
608 * Some back-ends can only ensure a certain min
609 * num of bytes read, which may be > 'count'.
610 * Let the tty clear the flip buff to make room.
612 poll_mask
|= HVC_POLL_READ
;
616 for (i
= 0; i
< n
; ++i
) {
617 #ifdef CONFIG_MAGIC_SYSRQ
618 if (hp
->index
== hvc_con_driver
.index
) {
619 /* Handle the SysRq Hack */
620 /* XXX should support a sequence */
621 if (buf
[i
] == '\x0f') { /* ^O */
624 } else if (sysrq_pressed
) {
625 handle_sysrq(buf
[i
], NULL
, tty
);
630 #endif /* CONFIG_MAGIC_SYSRQ */
631 tty_insert_flip_char(tty
, buf
[i
], 0);
637 /* Wakeup write queue if necessary */
643 spin_unlock_irqrestore(&hp
->lock
, flags
);
646 tty_flip_buffer_push(tty
);
651 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
652 extern cpumask_t cpus_in_xmon
;
654 static const cpumask_t cpus_in_xmon
= CPU_MASK_NONE
;
658 * This kthread is either polling or interrupt driven. This is determined by
659 * calling hvc_poll() who determines whether a console adapter support
662 int khvcd(void *unused
)
665 struct hvc_struct
*hp
;
667 __set_current_state(TASK_RUNNING
);
672 if (cpus_empty(cpus_in_xmon
)) {
673 spin_lock(&hvc_structs_lock
);
674 list_for_each_entry(hp
, &hvc_structs
, next
) {
675 poll_mask
|= hvc_poll(hp
);
677 spin_unlock(&hvc_structs_lock
);
679 poll_mask
|= HVC_POLL_READ
;
682 if (poll_mask
& HVC_POLL_WRITE
) {
686 set_current_state(TASK_INTERRUPTIBLE
);
691 msleep_interruptible(TIMEOUT
);
693 __set_current_state(TASK_RUNNING
);
694 } while (!kthread_should_stop());
699 static struct tty_operations hvc_ops
= {
703 .hangup
= hvc_hangup
,
704 .unthrottle
= hvc_unthrottle
,
705 .write_room
= hvc_write_room
,
706 .chars_in_buffer
= hvc_chars_in_buffer
,
709 /* callback when the kboject ref count reaches zero. */
710 static void destroy_hvc_struct(struct kobject
*kobj
)
712 struct hvc_struct
*hp
= container_of(kobj
, struct hvc_struct
, kobj
);
715 spin_lock(&hvc_structs_lock
);
717 spin_lock_irqsave(&hp
->lock
, flags
);
718 list_del(&(hp
->next
));
719 spin_unlock_irqrestore(&hp
->lock
, flags
);
721 spin_unlock(&hvc_structs_lock
);
726 static struct kobj_type hvc_kobj_type
= {
727 .release
= destroy_hvc_struct
,
730 struct hvc_struct __devinit
*hvc_alloc(uint32_t vtermno
, int irq
,
733 struct hvc_struct
*hp
;
736 hp
= kmalloc(sizeof(*hp
), GFP_KERNEL
);
738 return ERR_PTR(-ENOMEM
);
740 memset(hp
, 0x00, sizeof(*hp
));
742 hp
->vtermno
= vtermno
;
746 kobject_init(&hp
->kobj
);
747 hp
->kobj
.ktype
= &hvc_kobj_type
;
749 spin_lock_init(&hp
->lock
);
750 spin_lock(&hvc_structs_lock
);
754 * see if this vterm id matches one registered for console.
756 for (i
=0; i
< MAX_NR_HVC_CONSOLES
; i
++)
757 if (vtermnos
[i
] == hp
->vtermno
&&
758 cons_ops
[i
] == hp
->ops
)
761 /* no matching slot, just use a counter */
762 if (i
>= MAX_NR_HVC_CONSOLES
)
767 list_add_tail(&(hp
->next
), &hvc_structs
);
768 spin_unlock(&hvc_structs_lock
);
772 EXPORT_SYMBOL(hvc_alloc
);
774 int __devexit
hvc_remove(struct hvc_struct
*hp
)
777 struct kobject
*kobjp
;
778 struct tty_struct
*tty
;
780 spin_lock_irqsave(&hp
->lock
, flags
);
784 if (hp
->index
< MAX_NR_HVC_CONSOLES
)
785 vtermnos
[hp
->index
] = -1;
787 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
789 spin_unlock_irqrestore(&hp
->lock
, flags
);
792 * We 'put' the instance that was grabbed when the kobject instance
793 * was intialized using kobject_init(). Let the last holder of this
794 * kobject cause it to be removed, which will probably be the tty_hangup
800 * This function call will auto chain call hvc_hangup. The tty should
801 * always be valid at this time unless a simultaneous tty close already
802 * cleaned up the hvc_struct.
808 EXPORT_SYMBOL(hvc_remove
);
810 /* Driver initialization. Follow console initialization. This is where the TTY
811 * interfaces start to become available. */
812 int __init
hvc_init(void)
814 struct tty_driver
*drv
;
816 /* We need more than hvc_count adapters due to hotplug additions. */
817 drv
= alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS
);
821 drv
->owner
= THIS_MODULE
;
822 drv
->driver_name
= "hvc";
824 drv
->major
= HVC_MAJOR
;
825 drv
->minor_start
= HVC_MINOR
;
826 drv
->type
= TTY_DRIVER_TYPE_SYSTEM
;
827 drv
->init_termios
= tty_std_termios
;
828 drv
->flags
= TTY_DRIVER_REAL_RAW
;
829 tty_set_operations(drv
, &hvc_ops
);
831 /* Always start the kthread because there can be hotplug vty adapters
833 hvc_task
= kthread_run(khvcd
, NULL
, "khvcd");
834 if (IS_ERR(hvc_task
)) {
835 panic("Couldn't create kthread for console.\n");
840 if (tty_register_driver(drv
))
841 panic("Couldn't register hvc console driver\n");
847 module_init(hvc_init
);
849 /* This isn't particularily necessary due to this being a console driver
850 * but it is nice to be thorough.
852 static void __exit
hvc_exit(void)
854 kthread_stop(hvc_task
);
856 tty_unregister_driver(hvc_driver
);
857 /* return tty_struct instances allocated in hvc_init(). */
858 put_tty_driver(hvc_driver
);
859 unregister_console(&hvc_con_driver
);
861 module_exit(hvc_exit
);