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/config.h>
26 #include <linux/console.h>
27 #include <linux/cpumask.h>
28 #include <linux/init.h>
29 #include <linux/kbd_kern.h>
30 #include <linux/kernel.h>
31 #include <linux/kobject.h>
32 #include <linux/kthread.h>
33 #include <linux/list.h>
34 #include <linux/module.h>
35 #include <linux/major.h>
36 #include <linux/sysrq.h>
37 #include <linux/tty.h>
38 #include <linux/tty_flip.h>
39 #include <linux/sched.h>
40 #include <linux/spinlock.h>
41 #include <linux/delay.h>
42 #include <asm/uaccess.h>
43 #include <asm/hvconsole.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 * The Linux TTY code does not support dynamic addition of tty derived devices
59 * so we need to know how many tty devices we might need when space is allocated
60 * for the tty device. Since this driver supports hotplug of vty adapters we
61 * need to make sure we have enough allocated.
63 #define HVC_ALLOC_TTY_ADAPTERS 8
68 #define __ALIGNED__ __attribute__((__aligned__(8)))
70 static struct tty_driver *hvc_driver;
71 static struct task_struct *hvc_task;
73 /* Picks up late kicks after list walk but before schedule() */
74 static int hvc_kicked;
76 #ifdef CONFIG_MAGIC_SYSRQ
77 static int sysrq_pressed;
83 struct tty_struct *tty;
86 char outbuf[N_OUTBUF] __ALIGNED__;
91 struct list_head next;
92 struct kobject kobj; /* ref count & hvc_struct lifetime */
96 /* dynamic list of hvc_struct instances */
97 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
100 * Protect the list of hvc_struct instances from inserts and removals during
103 static DEFINE_SPINLOCK(hvc_structs_lock);
106 * This value is used to assign a tty->index value to a hvc_struct based
107 * upon order of exposure via hvc_probe(), when we can not match it to
108 * a console canidate registered with hvc_instantiate().
110 static int last_hvc = -1;
113 * Do not call this function with either the hvc_strucst_lock or the hvc_struct
114 * lock held. If successful, this function increments the kobject reference
115 * count against the target hvc_struct so it should be released when finished.
117 struct hvc_struct *hvc_get_by_index(int index)
119 struct hvc_struct *hp;
122 spin_lock(&hvc_structs_lock);
124 list_for_each_entry(hp, &hvc_structs, next) {
125 spin_lock_irqsave(&hp->lock, flags);
126 if (hp->index == index) {
127 kobject_get(&hp->kobj);
128 spin_unlock_irqrestore(&hp->lock, flags);
129 spin_unlock(&hvc_structs_lock);
132 spin_unlock_irqrestore(&hp->lock, flags);
136 spin_unlock(&hvc_structs_lock);
142 * Initial console vtermnos for console API usage prior to full console
143 * initialization. Any vty adapter outside this range will not have usable
144 * console interfaces but can still be used as a tty device. This has to be
145 * static because kmalloc will not work during early console init.
147 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
148 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
151 * Console APIs, NOT TTY. These APIs are available immediately when
152 * hvc_console_setup() finds adapters.
155 void hvc_console_print(struct console *co, const char *b, unsigned count)
157 char c[16] __ALIGNED__;
158 unsigned i = 0, n = 0;
161 /* Console access attempt outside of acceptable console range. */
162 if (co->index >= MAX_NR_HVC_CONSOLES)
165 /* This console adapter was removed so it is not useable. */
166 if (vtermnos[co->index] < 0)
169 while (count > 0 || i > 0) {
170 if (count > 0 && i < sizeof(c)) {
171 if (b[n] == '\n' && !donecr) {
180 r = hvc_put_chars(vtermnos[co->index], c, i);
182 /* throw away chars on error */
193 static struct tty_driver *hvc_console_device(struct console *c, int *index)
195 if (vtermnos[c->index] == -1)
202 static int __init hvc_console_setup(struct console *co, char *options)
204 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
207 if (vtermnos[co->index] == -1)
213 struct console hvc_con_driver = {
215 .write = hvc_console_print,
216 .device = hvc_console_device,
217 .setup = hvc_console_setup,
218 .flags = CON_PRINTBUFFER,
222 /* Early console initialization. Preceeds driver initialization. */
223 static int __init hvc_console_init(void)
226 register_console(&hvc_con_driver);
229 console_initcall(hvc_console_init);
232 * hvc_instantiate() is an early console discovery method which locates
233 * consoles * prior to the vio subsystem discovering them. Hotplugged
234 * vty adapters do NOT get an hvc_instantiate() callback since they
235 * appear after early console init.
237 int hvc_instantiate(uint32_t vtermno, int index)
239 struct hvc_struct *hp;
241 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
244 if (vtermnos[index] != -1)
247 /* make sure no no tty has been registerd in this index */
248 hp = hvc_get_by_index(index);
250 kobject_put(&hp->kobj);
254 vtermnos[index] = vtermno;
256 /* reserve all indices upto and including this index */
257 if (last_hvc < index)
263 /* Wake the sleeping khvcd */
264 static void hvc_kick(void)
267 wake_up_process(hvc_task);
270 static int hvc_poll(struct hvc_struct *hp);
273 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
274 * In this case the console is poll driven.
276 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
278 /* if hvc_poll request a repoll, then kick the hvcd thread */
279 if (hvc_poll(dev_instance))
284 static void hvc_unthrottle(struct tty_struct *tty)
290 * The TTY interface won't be used until after the vio layer has exposed the vty
291 * adapter to the kernel.
293 static int hvc_open(struct tty_struct *tty, struct file * filp)
295 struct hvc_struct *hp;
299 struct kobject *kobjp;
301 /* Auto increments kobject reference if found. */
302 if (!(hp = hvc_get_by_index(tty->index))) {
303 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
307 spin_lock_irqsave(&hp->lock, flags);
308 /* Check and then increment for fast path open. */
309 if (hp->count++ > 0) {
310 spin_unlock_irqrestore(&hp->lock, flags);
313 } /* else count == 0 */
315 tty->driver_data = hp;
317 /* Save for request_irq outside of spin_lock. */
320 hp->irq_requested = 1;
324 spin_unlock_irqrestore(&hp->lock, flags);
325 /* check error, fallback to non-irq */
327 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
330 * If the request_irq() fails and we return an error. The tty layer
331 * will call hvc_close() after a failed open but we don't want to clean
332 * up there so we'll clean up here and clear out the previously set
333 * tty fields and return the kobject reference.
336 spin_lock_irqsave(&hp->lock, flags);
338 hp->irq_requested = 0;
339 spin_unlock_irqrestore(&hp->lock, flags);
340 tty->driver_data = NULL;
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;
353 struct kobject *kobjp;
357 if (tty_hung_up_p(filp))
361 * No driver_data means that this close was issued after a failed
362 * hvc_open by the tty layer's release_dev() function and we can just
363 * exit cleanly because the kobject reference wasn't made.
365 if (!tty->driver_data)
368 hp = tty->driver_data;
369 spin_lock_irqsave(&hp->lock, flags);
372 if (--hp->count == 0) {
373 if (hp->irq_requested)
375 hp->irq_requested = 0;
377 /* We are done with the tty pointer now. */
379 spin_unlock_irqrestore(&hp->lock, flags);
382 * Chain calls chars_in_buffer() and returns immediately if
383 * there is no buffered data otherwise sleeps on a wait queue
384 * waking periodically to check chars_in_buffer().
386 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
393 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
394 hp->vtermno, hp->count);
395 spin_unlock_irqrestore(&hp->lock, flags);
401 static void hvc_hangup(struct tty_struct *tty)
403 struct hvc_struct *hp = tty->driver_data;
407 struct kobject *kobjp;
412 spin_lock_irqsave(&hp->lock, flags);
415 * The N_TTY line discipline has problems such that in a close vs
416 * open->hangup case this can be called after the final close so prevent
417 * that from happening for now.
419 if (hp->count <= 0) {
420 spin_unlock_irqrestore(&hp->lock, flags);
425 temp_open_count = hp->count;
429 if (hp->irq_requested)
430 /* Saved for use outside of spin_lock. */
432 hp->irq_requested = 0;
433 spin_unlock_irqrestore(&hp->lock, flags);
436 while(temp_open_count) {
443 * Push buffered characters whether they were just recently buffered or waiting
444 * on a blocked hypervisor. Call this function with hp->lock held.
446 static void hvc_push(struct hvc_struct *hp)
450 n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
454 /* throw away output on error; this happens when
455 there is no session connected to the vterm. */
459 if (hp->n_outbuf > 0)
460 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
465 static inline int __hvc_write_kernel(struct hvc_struct *hp,
466 const unsigned char *buf, int count)
469 int rsize, written = 0;
471 spin_lock_irqsave(&hp->lock, flags);
473 /* Push pending writes */
474 if (hp->n_outbuf > 0)
477 while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
480 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
483 hp->n_outbuf += rsize;
487 spin_unlock_irqrestore(&hp->lock, flags);
491 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
493 struct hvc_struct *hp = tty->driver_data;
496 /* This write was probably executed during a tty close. */
503 written = __hvc_write_kernel(hp, buf, count);
506 * Racy, but harmless, kick thread if there is still pending data.
507 * There really is nothing wrong with kicking the thread, even if there
508 * is no buffered data.
517 * This is actually a contract between the driver and the tty layer outlining
518 * how much write room the driver can guarentee will be sent OR BUFFERED. This
519 * driver MUST honor the return value.
521 static int hvc_write_room(struct tty_struct *tty)
523 struct hvc_struct *hp = tty->driver_data;
528 return N_OUTBUF - hp->n_outbuf;
531 static int hvc_chars_in_buffer(struct tty_struct *tty)
533 struct hvc_struct *hp = tty->driver_data;
540 #define HVC_POLL_READ 0x00000001
541 #define HVC_POLL_WRITE 0x00000002
542 #define HVC_POLL_QUICK 0x00000004
544 static int hvc_poll(struct hvc_struct *hp)
546 struct tty_struct *tty;
547 int i, n, poll_mask = 0;
548 char buf[N_INBUF] __ALIGNED__;
552 spin_lock_irqsave(&hp->lock, flags);
554 /* Push pending writes */
555 if (hp->n_outbuf > 0)
557 /* Reschedule us if still some write pending */
558 if (hp->n_outbuf > 0)
559 poll_mask |= HVC_POLL_WRITE;
561 /* No tty attached, just skip */
566 /* Now check if we can get data (are we throttled ?) */
567 if (test_bit(TTY_THROTTLED, &tty->flags))
570 /* If we aren't interrupt driven and aren't throttled, we always
571 * request a reschedule
573 if (hp->irq == NO_IRQ)
574 poll_mask |= HVC_POLL_READ;
576 /* Read data if any */
579 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
580 count = TTY_FLIPBUF_SIZE - tty->flip.count;
582 /* If flip is full, just reschedule a later read */
584 poll_mask |= HVC_POLL_READ;
588 n = hvc_get_chars(hp->vtermno, buf, count);
590 /* Hangup the tty when disconnected from host */
592 spin_unlock_irqrestore(&hp->lock, flags);
594 spin_lock_irqsave(&hp->lock, flags);
598 for (i = 0; i < n; ++i) {
599 #ifdef CONFIG_MAGIC_SYSRQ
600 if (hp->index == hvc_con_driver.index) {
601 /* Handle the SysRq Hack */
602 /* XXX should support a sequence */
603 if (buf[i] == '\x0f') { /* ^O */
606 } else if (sysrq_pressed) {
607 handle_sysrq(buf[i], NULL, tty);
612 #endif /* CONFIG_MAGIC_SYSRQ */
613 tty_insert_flip_char(tty, buf[i], 0);
617 tty_schedule_flip(tty);
620 * Account for the total amount read in one loop, and if above
621 * 64 bytes, we do a quick schedule loop to let the tty grok
622 * the data and eventually throttle us.
625 if (read_total >= 64) {
626 poll_mask |= HVC_POLL_QUICK;
631 /* Wakeup write queue if necessary */
637 spin_unlock_irqrestore(&hp->lock, flags);
642 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
643 extern cpumask_t cpus_in_xmon;
645 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
649 * This kthread is either polling or interrupt driven. This is determined by
650 * calling hvc_poll() who determines whether a console adapter support
653 int khvcd(void *unused)
656 struct hvc_struct *hp;
658 __set_current_state(TASK_RUNNING);
663 if (cpus_empty(cpus_in_xmon)) {
664 spin_lock(&hvc_structs_lock);
665 list_for_each_entry(hp, &hvc_structs, next) {
666 poll_mask |= hvc_poll(hp);
668 spin_unlock(&hvc_structs_lock);
670 poll_mask |= HVC_POLL_READ;
673 if (poll_mask & HVC_POLL_QUICK) {
677 set_current_state(TASK_INTERRUPTIBLE);
682 msleep_interruptible(TIMEOUT);
684 __set_current_state(TASK_RUNNING);
685 } while (!kthread_should_stop());
690 static struct tty_operations hvc_ops = {
694 .hangup = hvc_hangup,
695 .unthrottle = hvc_unthrottle,
696 .write_room = hvc_write_room,
697 .chars_in_buffer = hvc_chars_in_buffer,
700 /* callback when the kboject ref count reaches zero. */
701 static void destroy_hvc_struct(struct kobject *kobj)
703 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
706 spin_lock(&hvc_structs_lock);
708 spin_lock_irqsave(&hp->lock, flags);
709 list_del(&(hp->next));
710 spin_unlock_irqrestore(&hp->lock, flags);
712 spin_unlock(&hvc_structs_lock);
717 static struct kobj_type hvc_kobj_type = {
718 .release = destroy_hvc_struct,
721 static int __devinit hvc_probe(
723 const struct vio_device_id *id)
725 struct hvc_struct *hp;
728 /* probed with invalid parameters. */
732 hp = kmalloc(sizeof(*hp), GFP_KERNEL);
736 memset(hp, 0x00, sizeof(*hp));
737 hp->vtermno = dev->unit_address;
739 hp->vdev->dev.driver_data = hp;
742 kobject_init(&hp->kobj);
743 hp->kobj.ktype = &hvc_kobj_type;
745 spin_lock_init(&hp->lock);
746 spin_lock(&hvc_structs_lock);
750 * see if this vterm id matches one registered for console.
752 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
753 if (vtermnos[i] == hp->vtermno)
756 /* no matching slot, just use a counter */
757 if (i >= MAX_NR_HVC_CONSOLES)
762 list_add_tail(&(hp->next), &hvc_structs);
763 spin_unlock(&hvc_structs_lock);
768 static int __devexit hvc_remove(struct vio_dev *dev)
770 struct hvc_struct *hp = dev->dev.driver_data;
772 struct kobject *kobjp;
773 struct tty_struct *tty;
775 spin_lock_irqsave(&hp->lock, flags);
779 if (hp->index < MAX_NR_HVC_CONSOLES)
780 vtermnos[hp->index] = -1;
782 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
784 spin_unlock_irqrestore(&hp->lock, flags);
787 * We 'put' the instance that was grabbed when the kobject instance
788 * was intialized using kobject_init(). Let the last holder of this
789 * kobject cause it to be removed, which will probably be the tty_hangup
795 * This function call will auto chain call hvc_hangup. The tty should
796 * always be valid at this time unless a simultaneous tty close already
797 * cleaned up the hvc_struct.
804 char hvc_driver_name[] = "hvc_console";
806 static struct vio_device_id hvc_driver_table[] __devinitdata= {
807 {"serial", "hvterm1"},
810 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
812 static struct vio_driver hvc_vio_driver = {
813 .name = hvc_driver_name,
814 .id_table = hvc_driver_table,
816 .remove = hvc_remove,
819 /* Driver initialization. Follow console initialization. This is where the TTY
820 * interfaces start to become available. */
821 int __init hvc_init(void)
825 /* We need more than hvc_count adapters due to hotplug additions. */
826 hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
830 hvc_driver->owner = THIS_MODULE;
831 hvc_driver->devfs_name = "hvc/";
832 hvc_driver->driver_name = "hvc";
833 hvc_driver->name = "hvc";
834 hvc_driver->major = HVC_MAJOR;
835 hvc_driver->minor_start = HVC_MINOR;
836 hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
837 hvc_driver->init_termios = tty_std_termios;
838 hvc_driver->flags = TTY_DRIVER_REAL_RAW;
839 tty_set_operations(hvc_driver, &hvc_ops);
841 if (tty_register_driver(hvc_driver))
842 panic("Couldn't register hvc console driver\n");
844 /* Always start the kthread because there can be hotplug vty adapters
846 hvc_task = kthread_run(khvcd, NULL, "khvcd");
847 if (IS_ERR(hvc_task)) {
848 panic("Couldn't create kthread for console.\n");
849 put_tty_driver(hvc_driver);
853 /* Register as a vio device to receive callbacks */
854 rc = vio_register_driver(&hvc_vio_driver);
858 module_init(hvc_init);
860 /* This isn't particularily necessary due to this being a console driver
861 * but it is nice to be thorough.
863 static void __exit hvc_exit(void)
865 kthread_stop(hvc_task);
867 vio_unregister_driver(&hvc_vio_driver);
868 tty_unregister_driver(hvc_driver);
869 /* return tty_struct instances allocated in hvc_init(). */
870 put_tty_driver(hvc_driver);
871 unregister_console(&hvc_con_driver);
873 module_exit(hvc_exit);