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>
41 #include <linux/slab.h>
42 #include <linux/serial_core.h>
44 #include <asm/uaccess.h>
46 #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 static int hvc_init(void);
75 #ifdef CONFIG_MAGIC_SYSRQ
76 static int sysrq_pressed;
79 /* dynamic list of hvc_struct instances */
80 static LIST_HEAD(hvc_structs);
83 * Protect the list of hvc_struct instances from inserts and removals during
86 static DEFINE_SPINLOCK(hvc_structs_lock);
89 * This value is used to assign a tty->index value to a hvc_struct based
90 * upon order of exposure via hvc_probe(), when we can not match it to
91 * a console candidate registered with hvc_instantiate().
93 static int last_hvc = -1;
96 * Do not call this function with either the hvc_structs_lock or the hvc_struct
97 * lock held. If successful, this function increments the kref reference
98 * count against the target hvc_struct so it should be released when finished.
100 static struct hvc_struct *hvc_get_by_index(int index)
102 struct hvc_struct *hp;
105 spin_lock(&hvc_structs_lock);
107 list_for_each_entry(hp, &hvc_structs, next) {
108 spin_lock_irqsave(&hp->lock, flags);
109 if (hp->index == index) {
110 tty_port_get(&hp->port);
111 spin_unlock_irqrestore(&hp->lock, flags);
112 spin_unlock(&hvc_structs_lock);
115 spin_unlock_irqrestore(&hp->lock, flags);
119 spin_unlock(&hvc_structs_lock);
125 * Initial console vtermnos for console API usage prior to full console
126 * initialization. Any vty adapter outside this range will not have usable
127 * console interfaces but can still be used as a tty device. This has to be
128 * static because kmalloc will not work during early console init.
130 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
131 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
132 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
135 * Console APIs, NOT TTY. These APIs are available immediately when
136 * hvc_console_setup() finds adapters.
139 static void hvc_console_print(struct console *co, const char *b,
142 char c[N_OUTBUF] __ALIGNED__;
143 unsigned i = 0, n = 0;
144 int r, donecr = 0, index = co->index;
146 /* Console access attempt outside of acceptable console range. */
147 if (index >= MAX_NR_HVC_CONSOLES)
150 /* This console adapter was removed so it is not usable. */
151 if (vtermnos[index] == -1)
154 while (count > 0 || i > 0) {
155 if (count > 0 && i < sizeof(c)) {
156 if (b[n] == '\n' && !donecr) {
165 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
167 /* throw away characters on error
168 * but spin in case of -EAGAIN */
180 static struct tty_driver *hvc_console_device(struct console *c, int *index)
182 if (vtermnos[c->index] == -1)
189 static int __init hvc_console_setup(struct console *co, char *options)
191 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
194 if (vtermnos[co->index] == -1)
200 static struct console hvc_console = {
202 .write = hvc_console_print,
203 .device = hvc_console_device,
204 .setup = hvc_console_setup,
205 .flags = CON_PRINTBUFFER,
210 * Early console initialization. Precedes driver initialization.
212 * (1) we are first, and the user specified another driver
213 * -- index will remain -1
214 * (2) we are first and the user specified no driver
215 * -- index will be set to 0, then we will fail setup.
216 * (3) we are first and the user specified our driver
217 * -- index will be set to user specified driver, and we will fail
218 * (4) we are after driver, and this initcall will register us
219 * -- if the user didn't specify a driver then the console will match
221 * Note that for cases 2 and 3, we will match later when the io driver
222 * calls hvc_instantiate() and call register again.
224 static int __init hvc_console_init(void)
226 register_console(&hvc_console);
229 console_initcall(hvc_console_init);
231 /* callback when the kboject ref count reaches zero. */
232 static void hvc_port_destruct(struct tty_port *port)
234 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
237 spin_lock(&hvc_structs_lock);
239 spin_lock_irqsave(&hp->lock, flags);
240 list_del(&(hp->next));
241 spin_unlock_irqrestore(&hp->lock, flags);
243 spin_unlock(&hvc_structs_lock);
248 static void hvc_check_console(int index)
250 /* Already enabled, bail out */
251 if (hvc_console.flags & CON_ENABLED)
254 /* If this index is what the user requested, then register
255 * now (setup won't fail at this point). It's ok to just
256 * call register again if previously .setup failed.
258 if (index == hvc_console.index)
259 register_console(&hvc_console);
263 * hvc_instantiate() is an early console discovery method which locates
264 * consoles * prior to the vio subsystem discovering them. Hotplugged
265 * vty adapters do NOT get an hvc_instantiate() callback since they
266 * appear after early console init.
268 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
270 struct hvc_struct *hp;
272 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
275 if (vtermnos[index] != -1)
278 /* make sure no no tty has been registered in this index */
279 hp = hvc_get_by_index(index);
281 tty_port_put(&hp->port);
285 vtermnos[index] = vtermno;
286 cons_ops[index] = ops;
288 /* reserve all indices up to and including this index */
289 if (last_hvc < index)
292 /* check if we need to re-register the kernel console */
293 hvc_check_console(index);
297 EXPORT_SYMBOL_GPL(hvc_instantiate);
299 /* Wake the sleeping khvcd */
303 wake_up_process(hvc_task);
305 EXPORT_SYMBOL_GPL(hvc_kick);
307 static void hvc_unthrottle(struct tty_struct *tty)
313 * The TTY interface won't be used until after the vio layer has exposed the vty
314 * adapter to the kernel.
316 static int hvc_open(struct tty_struct *tty, struct file * filp)
318 struct hvc_struct *hp;
322 /* Auto increments kref reference if found. */
323 if (!(hp = hvc_get_by_index(tty->index)))
326 spin_lock_irqsave(&hp->port.lock, flags);
327 /* Check and then increment for fast path open. */
328 if (hp->port.count++ > 0) {
329 spin_unlock_irqrestore(&hp->port.lock, flags);
332 } /* else count == 0 */
333 spin_unlock_irqrestore(&hp->port.lock, flags);
335 tty->driver_data = hp;
336 tty_port_tty_set(&hp->port, tty);
338 if (hp->ops->notifier_add)
339 rc = hp->ops->notifier_add(hp, hp->data);
342 * If the notifier fails we return an error. The tty layer
343 * will call hvc_close() after a failed open but we don't want to clean
344 * up there so we'll clean up here and clear out the previously set
345 * tty fields and return the kref reference.
348 tty_port_tty_set(&hp->port, NULL);
349 tty->driver_data = NULL;
350 tty_port_put(&hp->port);
351 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
353 /* Force wakeup of the polling thread */
359 static void hvc_close(struct tty_struct *tty, struct file * filp)
361 struct hvc_struct *hp;
364 if (tty_hung_up_p(filp))
368 * No driver_data means that this close was issued after a failed
369 * hvc_open by the tty layer's release_dev() function and we can just
370 * exit cleanly because the kref reference wasn't made.
372 if (!tty->driver_data)
375 hp = tty->driver_data;
377 spin_lock_irqsave(&hp->port.lock, flags);
379 if (--hp->port.count == 0) {
380 spin_unlock_irqrestore(&hp->port.lock, flags);
381 /* We are done with the tty pointer now. */
382 tty_port_tty_set(&hp->port, NULL);
384 if (hp->ops->notifier_del)
385 hp->ops->notifier_del(hp, hp->data);
387 /* cancel pending tty resize work */
388 cancel_work_sync(&hp->tty_resize);
391 * Chain calls chars_in_buffer() and returns immediately if
392 * there is no buffered data otherwise sleeps on a wait queue
393 * waking periodically to check chars_in_buffer().
395 tty_wait_until_sent_from_close(tty, HVC_CLOSE_WAIT);
397 if (hp->port.count < 0)
398 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
399 hp->vtermno, hp->port.count);
400 spin_unlock_irqrestore(&hp->port.lock, flags);
403 tty_port_put(&hp->port);
406 static void hvc_hangup(struct tty_struct *tty)
408 struct hvc_struct *hp = tty->driver_data;
415 /* cancel pending tty resize work */
416 cancel_work_sync(&hp->tty_resize);
418 spin_lock_irqsave(&hp->port.lock, flags);
421 * The N_TTY line discipline has problems such that in a close vs
422 * open->hangup case this can be called after the final close so prevent
423 * that from happening for now.
425 if (hp->port.count <= 0) {
426 spin_unlock_irqrestore(&hp->port.lock, flags);
430 temp_open_count = hp->port.count;
432 spin_unlock_irqrestore(&hp->port.lock, flags);
433 tty_port_tty_set(&hp->port, NULL);
437 if (hp->ops->notifier_hangup)
438 hp->ops->notifier_hangup(hp, hp->data);
440 while(temp_open_count) {
442 tty_port_put(&hp->port);
447 * Push buffered characters whether they were just recently buffered or waiting
448 * on a blocked hypervisor. Call this function with hp->lock held.
450 static int hvc_push(struct hvc_struct *hp)
454 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
456 if (n == 0 || n == -EAGAIN) {
460 /* throw away output on error; this happens when
461 there is no session connected to the vterm. */
465 if (hp->n_outbuf > 0)
466 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
473 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
475 struct hvc_struct *hp = tty->driver_data;
477 int rsize, written = 0;
479 /* This write was probably executed during a tty close. */
483 /* FIXME what's this (unprotected) check for? */
484 if (hp->port.count <= 0)
487 spin_lock_irqsave(&hp->lock, flags);
489 /* Push pending writes */
490 if (hp->n_outbuf > 0)
493 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
496 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
499 hp->n_outbuf += rsize;
503 spin_unlock_irqrestore(&hp->lock, flags);
506 * Racy, but harmless, kick thread if there is still pending data.
515 * hvc_set_winsz() - Resize the hvc tty terminal window.
516 * @work: work structure.
518 * The routine shall not be called within an atomic context because it
523 static void hvc_set_winsz(struct work_struct *work)
525 struct hvc_struct *hp;
526 unsigned long hvc_flags;
527 struct tty_struct *tty;
530 hp = container_of(work, struct hvc_struct, tty_resize);
532 tty = tty_port_tty_get(&hp->port);
536 spin_lock_irqsave(&hp->lock, hvc_flags);
538 spin_unlock_irqrestore(&hp->lock, hvc_flags);
540 tty_do_resize(tty, &ws);
545 * This is actually a contract between the driver and the tty layer outlining
546 * how much write room the driver can guarantee will be sent OR BUFFERED. This
547 * driver MUST honor the return value.
549 static int hvc_write_room(struct tty_struct *tty)
551 struct hvc_struct *hp = tty->driver_data;
556 return hp->outbuf_size - hp->n_outbuf;
559 static int hvc_chars_in_buffer(struct tty_struct *tty)
561 struct hvc_struct *hp = tty->driver_data;
569 * timeout will vary between the MIN and MAX values defined here. By default
570 * and during console activity we will use a default MIN_TIMEOUT of 10. When
571 * the console is idle, we increase the timeout value on each pass through
572 * msleep until we reach the max. This may be noticeable as a brief (average
573 * one second) delay on the console before the console responds to input when
574 * there has been no input for some time.
576 #define MIN_TIMEOUT (10)
577 #define MAX_TIMEOUT (2000)
578 static u32 timeout = MIN_TIMEOUT;
580 #define HVC_POLL_READ 0x00000001
581 #define HVC_POLL_WRITE 0x00000002
583 int hvc_poll(struct hvc_struct *hp)
585 struct tty_struct *tty;
586 int i, n, poll_mask = 0;
587 char buf[N_INBUF] __ALIGNED__;
590 int written_total = 0;
592 spin_lock_irqsave(&hp->lock, flags);
594 /* Push pending writes */
595 if (hp->n_outbuf > 0)
596 written_total = hvc_push(hp);
598 /* Reschedule us if still some write pending */
599 if (hp->n_outbuf > 0) {
600 poll_mask |= HVC_POLL_WRITE;
601 /* If hvc_push() was not able to write, sleep a few msecs */
602 timeout = (written_total) ? 0 : MIN_TIMEOUT;
605 /* No tty attached, just skip */
606 tty = tty_port_tty_get(&hp->port);
610 /* Now check if we can get data (are we throttled ?) */
611 if (test_bit(TTY_THROTTLED, &tty->flags))
614 /* If we aren't notifier driven and aren't throttled, we always
615 * request a reschedule
617 if (!hp->irq_requested)
618 poll_mask |= HVC_POLL_READ;
620 /* Read data if any */
622 int count = tty_buffer_request_room(tty, N_INBUF);
624 /* If flip is full, just reschedule a later read */
626 poll_mask |= HVC_POLL_READ;
630 n = hp->ops->get_chars(hp->vtermno, buf, count);
632 /* Hangup the tty when disconnected from host */
634 spin_unlock_irqrestore(&hp->lock, flags);
636 spin_lock_irqsave(&hp->lock, flags);
637 } else if ( n == -EAGAIN ) {
639 * Some back-ends can only ensure a certain min
640 * num of bytes read, which may be > 'count'.
641 * Let the tty clear the flip buff to make room.
643 poll_mask |= HVC_POLL_READ;
647 for (i = 0; i < n; ++i) {
648 #ifdef CONFIG_MAGIC_SYSRQ
649 if (hp->index == hvc_console.index) {
650 /* Handle the SysRq Hack */
651 /* XXX should support a sequence */
652 if (buf[i] == '\x0f') { /* ^O */
653 /* if ^O is pressed again, reset
654 * sysrq_pressed and flip ^O char */
655 sysrq_pressed = !sysrq_pressed;
658 } else if (sysrq_pressed) {
659 handle_sysrq(buf[i]);
664 #endif /* CONFIG_MAGIC_SYSRQ */
665 tty_insert_flip_char(tty, buf[i], 0);
671 /* Wakeup write queue if necessary */
677 spin_unlock_irqrestore(&hp->lock, flags);
680 /* Activity is occurring, so reset the polling backoff value to
681 a minimum for performance. */
682 timeout = MIN_TIMEOUT;
684 tty_flip_buffer_push(tty);
690 EXPORT_SYMBOL_GPL(hvc_poll);
693 * __hvc_resize() - Update terminal window size information.
694 * @hp: HVC console pointer
695 * @ws: Terminal window size structure
697 * Stores the specified window size information in the hvc structure of @hp.
698 * The function schedule the tty resize update.
700 * Locking: Locking free; the function MUST be called holding hp->lock
702 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
705 schedule_work(&hp->tty_resize);
707 EXPORT_SYMBOL_GPL(__hvc_resize);
710 * This kthread is either polling or interrupt driven. This is determined by
711 * calling hvc_poll() who determines whether a console adapter support
714 static int khvcd(void *unused)
717 struct hvc_struct *hp;
725 if (!cpus_are_in_xmon()) {
726 spin_lock(&hvc_structs_lock);
727 list_for_each_entry(hp, &hvc_structs, next) {
728 poll_mask |= hvc_poll(hp);
730 spin_unlock(&hvc_structs_lock);
732 poll_mask |= HVC_POLL_READ;
735 set_current_state(TASK_INTERRUPTIBLE);
740 if (timeout < MAX_TIMEOUT)
741 timeout += (timeout >> 6) + 1;
743 msleep_interruptible(timeout);
746 __set_current_state(TASK_RUNNING);
747 } while (!kthread_should_stop());
752 static int hvc_tiocmget(struct tty_struct *tty)
754 struct hvc_struct *hp = tty->driver_data;
756 if (!hp || !hp->ops->tiocmget)
758 return hp->ops->tiocmget(hp);
761 static int hvc_tiocmset(struct tty_struct *tty,
762 unsigned int set, unsigned int clear)
764 struct hvc_struct *hp = tty->driver_data;
766 if (!hp || !hp->ops->tiocmset)
768 return hp->ops->tiocmset(hp, set, clear);
771 #ifdef CONFIG_CONSOLE_POLL
772 int hvc_poll_init(struct tty_driver *driver, int line, char *options)
777 static int hvc_poll_get_char(struct tty_driver *driver, int line)
779 struct tty_struct *tty = driver->ttys[0];
780 struct hvc_struct *hp = tty->driver_data;
784 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
792 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
794 struct tty_struct *tty = driver->ttys[0];
795 struct hvc_struct *hp = tty->driver_data;
799 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
804 static const struct tty_operations hvc_ops = {
808 .hangup = hvc_hangup,
809 .unthrottle = hvc_unthrottle,
810 .write_room = hvc_write_room,
811 .chars_in_buffer = hvc_chars_in_buffer,
812 .tiocmget = hvc_tiocmget,
813 .tiocmset = hvc_tiocmset,
814 #ifdef CONFIG_CONSOLE_POLL
815 .poll_init = hvc_poll_init,
816 .poll_get_char = hvc_poll_get_char,
817 .poll_put_char = hvc_poll_put_char,
821 static const struct tty_port_operations hvc_port_ops = {
822 .destruct = hvc_port_destruct,
825 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
826 const struct hv_ops *ops,
829 struct hvc_struct *hp;
832 /* We wait until a driver actually comes along */
834 int err = hvc_init();
839 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
842 return ERR_PTR(-ENOMEM);
844 hp->vtermno = vtermno;
847 hp->outbuf_size = outbuf_size;
848 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
850 tty_port_init(&hp->port);
851 hp->port.ops = &hvc_port_ops;
853 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
854 spin_lock_init(&hp->lock);
855 spin_lock(&hvc_structs_lock);
859 * see if this vterm id matches one registered for console.
861 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
862 if (vtermnos[i] == hp->vtermno &&
863 cons_ops[i] == hp->ops)
866 /* no matching slot, just use a counter */
867 if (i >= MAX_NR_HVC_CONSOLES)
872 vtermnos[i] = vtermno;
874 list_add_tail(&(hp->next), &hvc_structs);
875 spin_unlock(&hvc_structs_lock);
877 /* check if we need to re-register the kernel console */
878 hvc_check_console(i);
882 EXPORT_SYMBOL_GPL(hvc_alloc);
884 int hvc_remove(struct hvc_struct *hp)
887 struct tty_struct *tty;
889 tty = tty_port_tty_get(&hp->port);
891 spin_lock_irqsave(&hp->lock, flags);
892 if (hp->index < MAX_NR_HVC_CONSOLES) {
894 vtermnos[hp->index] = -1;
895 cons_ops[hp->index] = NULL;
899 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
901 spin_unlock_irqrestore(&hp->lock, flags);
904 * We 'put' the instance that was grabbed when the kref instance
905 * was initialized using kref_init(). Let the last holder of this
906 * kref cause it to be removed, which will probably be the tty_vhangup
909 tty_port_put(&hp->port);
912 * This function call will auto chain call hvc_hangup.
920 EXPORT_SYMBOL_GPL(hvc_remove);
922 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
923 static int hvc_init(void)
925 struct tty_driver *drv;
928 /* We need more than hvc_count adapters due to hotplug additions. */
929 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
935 drv->driver_name = "hvc";
937 drv->major = HVC_MAJOR;
938 drv->minor_start = HVC_MINOR;
939 drv->type = TTY_DRIVER_TYPE_SYSTEM;
940 drv->init_termios = tty_std_termios;
941 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
942 tty_set_operations(drv, &hvc_ops);
944 /* Always start the kthread because there can be hotplug vty adapters
946 hvc_task = kthread_run(khvcd, NULL, "khvcd");
947 if (IS_ERR(hvc_task)) {
948 printk(KERN_ERR "Couldn't create kthread for console.\n");
949 err = PTR_ERR(hvc_task);
953 err = tty_register_driver(drv);
955 printk(KERN_ERR "Couldn't register hvc console driver\n");
960 * Make sure tty is fully registered before allowing it to be
961 * found by hvc_console_device.
968 kthread_stop(hvc_task);
976 /* This isn't particularly necessary due to this being a console driver
977 * but it is nice to be thorough.
979 static void __exit hvc_exit(void)
982 kthread_stop(hvc_task);
984 tty_unregister_driver(hvc_driver);
985 /* return tty_struct instances allocated in hvc_init(). */
986 put_tty_driver(hvc_driver);
987 unregister_console(&hvc_console);
990 module_exit(hvc_exit);