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];
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)
199 static int __init hvc_console_setup(struct console *co, char *options)
204 struct console hvc_con_driver = {
206 .write = hvc_console_print,
207 .device = hvc_console_device,
208 .setup = hvc_console_setup,
209 .flags = CON_PRINTBUFFER,
213 /* Early console initialization. Preceeds driver initialization. */
214 static int __init hvc_console_init(void)
218 for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
221 register_console(&hvc_con_driver);
224 console_initcall(hvc_console_init);
227 * hvc_instantiate() is an early console discovery method which locates
228 * consoles * prior to the vio subsystem discovering them. Hotplugged
229 * vty adapters do NOT get an hvc_instantiate() callback since they
230 * appear after early console init.
232 int hvc_instantiate(uint32_t vtermno, int index)
234 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
237 if (vtermnos[index] != -1)
240 vtermnos[index] = vtermno;
242 /* reserve all indices upto and including this index */
243 if (last_hvc < index)
249 /* Wake the sleeping khvcd */
250 static void hvc_kick(void)
253 wake_up_process(hvc_task);
256 static int hvc_poll(struct hvc_struct *hp);
259 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
260 * In this case the console is poll driven.
262 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
264 /* if hvc_poll request a repoll, then kick the hvcd thread */
265 if (hvc_poll(dev_instance))
270 static void hvc_unthrottle(struct tty_struct *tty)
276 * The TTY interface won't be used until after the vio layer has exposed the vty
277 * adapter to the kernel.
279 static int hvc_open(struct tty_struct *tty, struct file * filp)
281 struct hvc_struct *hp;
285 struct kobject *kobjp;
287 /* Auto increments kobject reference if found. */
288 if (!(hp = hvc_get_by_index(tty->index))) {
289 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
293 spin_lock_irqsave(&hp->lock, flags);
294 /* Check and then increment for fast path open. */
295 if (hp->count++ > 0) {
296 spin_unlock_irqrestore(&hp->lock, flags);
299 } /* else count == 0 */
301 tty->driver_data = hp;
303 /* Save for request_irq outside of spin_lock. */
306 hp->irq_requested = 1;
310 spin_unlock_irqrestore(&hp->lock, flags);
311 /* check error, fallback to non-irq */
313 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
316 * If the request_irq() fails and we return an error. The tty layer
317 * will call hvc_close() after a failed open but we don't want to clean
318 * up there so we'll clean up here and clear out the previously set
319 * tty fields and return the kobject reference.
322 spin_lock_irqsave(&hp->lock, flags);
324 hp->irq_requested = 0;
325 spin_unlock_irqrestore(&hp->lock, flags);
326 tty->driver_data = NULL;
328 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
330 /* Force wakeup of the polling thread */
336 static void hvc_close(struct tty_struct *tty, struct file * filp)
338 struct hvc_struct *hp;
339 struct kobject *kobjp;
343 if (tty_hung_up_p(filp))
347 * No driver_data means that this close was issued after a failed
348 * hvc_open by the tty layer's release_dev() function and we can just
349 * exit cleanly because the kobject reference wasn't made.
351 if (!tty->driver_data)
354 hp = tty->driver_data;
355 spin_lock_irqsave(&hp->lock, flags);
358 if (--hp->count == 0) {
359 if (hp->irq_requested)
361 hp->irq_requested = 0;
363 /* We are done with the tty pointer now. */
365 spin_unlock_irqrestore(&hp->lock, flags);
368 * Chain calls chars_in_buffer() and returns immediately if
369 * there is no buffered data otherwise sleeps on a wait queue
370 * waking periodically to check chars_in_buffer().
372 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
379 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
380 hp->vtermno, hp->count);
381 spin_unlock_irqrestore(&hp->lock, flags);
387 static void hvc_hangup(struct tty_struct *tty)
389 struct hvc_struct *hp = tty->driver_data;
393 struct kobject *kobjp;
398 spin_lock_irqsave(&hp->lock, flags);
401 * The N_TTY line discipline has problems such that in a close vs
402 * open->hangup case this can be called after the final close so prevent
403 * that from happening for now.
405 if (hp->count <= 0) {
406 spin_unlock_irqrestore(&hp->lock, flags);
411 temp_open_count = hp->count;
415 if (hp->irq_requested)
416 /* Saved for use outside of spin_lock. */
418 hp->irq_requested = 0;
419 spin_unlock_irqrestore(&hp->lock, flags);
422 while(temp_open_count) {
429 * Push buffered characters whether they were just recently buffered or waiting
430 * on a blocked hypervisor. Call this function with hp->lock held.
432 static void hvc_push(struct hvc_struct *hp)
436 n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
440 /* throw away output on error; this happens when
441 there is no session connected to the vterm. */
445 if (hp->n_outbuf > 0)
446 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
451 static inline int __hvc_write_kernel(struct hvc_struct *hp,
452 const unsigned char *buf, int count)
455 int rsize, written = 0;
457 spin_lock_irqsave(&hp->lock, flags);
459 /* Push pending writes */
460 if (hp->n_outbuf > 0)
463 while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
466 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
469 hp->n_outbuf += rsize;
473 spin_unlock_irqrestore(&hp->lock, flags);
477 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
479 struct hvc_struct *hp = tty->driver_data;
482 /* This write was probably executed during a tty close. */
489 written = __hvc_write_kernel(hp, buf, count);
492 * Racy, but harmless, kick thread if there is still pending data.
493 * There really is nothing wrong with kicking the thread, even if there
494 * is no buffered data.
503 * This is actually a contract between the driver and the tty layer outlining
504 * how much write room the driver can guarentee will be sent OR BUFFERED. This
505 * driver MUST honor the return value.
507 static int hvc_write_room(struct tty_struct *tty)
509 struct hvc_struct *hp = tty->driver_data;
514 return N_OUTBUF - hp->n_outbuf;
517 static int hvc_chars_in_buffer(struct tty_struct *tty)
519 struct hvc_struct *hp = tty->driver_data;
526 #define HVC_POLL_READ 0x00000001
527 #define HVC_POLL_WRITE 0x00000002
528 #define HVC_POLL_QUICK 0x00000004
530 static int hvc_poll(struct hvc_struct *hp)
532 struct tty_struct *tty;
533 int i, n, poll_mask = 0;
534 char buf[N_INBUF] __ALIGNED__;
538 spin_lock_irqsave(&hp->lock, flags);
540 /* Push pending writes */
541 if (hp->n_outbuf > 0)
543 /* Reschedule us if still some write pending */
544 if (hp->n_outbuf > 0)
545 poll_mask |= HVC_POLL_WRITE;
547 /* No tty attached, just skip */
552 /* Now check if we can get data (are we throttled ?) */
553 if (test_bit(TTY_THROTTLED, &tty->flags))
556 /* If we aren't interrupt driven and aren't throttled, we always
557 * request a reschedule
559 if (hp->irq == NO_IRQ)
560 poll_mask |= HVC_POLL_READ;
562 /* Read data if any */
565 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
566 count = TTY_FLIPBUF_SIZE - tty->flip.count;
568 /* If flip is full, just reschedule a later read */
570 poll_mask |= HVC_POLL_READ;
574 n = hvc_get_chars(hp->vtermno, buf, count);
576 /* Hangup the tty when disconnected from host */
578 spin_unlock_irqrestore(&hp->lock, flags);
580 spin_lock_irqsave(&hp->lock, flags);
584 for (i = 0; i < n; ++i) {
585 #ifdef CONFIG_MAGIC_SYSRQ
586 if (hp->index == hvc_con_driver.index) {
587 /* Handle the SysRq Hack */
588 /* XXX should support a sequence */
589 if (buf[i] == '\x0f') { /* ^O */
592 } else if (sysrq_pressed) {
593 handle_sysrq(buf[i], NULL, tty);
598 #endif /* CONFIG_MAGIC_SYSRQ */
599 tty_insert_flip_char(tty, buf[i], 0);
603 tty_schedule_flip(tty);
606 * Account for the total amount read in one loop, and if above
607 * 64 bytes, we do a quick schedule loop to let the tty grok
608 * the data and eventually throttle us.
611 if (read_total >= 64) {
612 poll_mask |= HVC_POLL_QUICK;
617 /* Wakeup write queue if necessary */
623 spin_unlock_irqrestore(&hp->lock, flags);
628 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
629 extern cpumask_t cpus_in_xmon;
631 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
635 * This kthread is either polling or interrupt driven. This is determined by
636 * calling hvc_poll() who determines whether a console adapter support
639 int khvcd(void *unused)
642 struct hvc_struct *hp;
644 __set_current_state(TASK_RUNNING);
649 if (cpus_empty(cpus_in_xmon)) {
650 spin_lock(&hvc_structs_lock);
651 list_for_each_entry(hp, &hvc_structs, next) {
652 poll_mask |= hvc_poll(hp);
654 spin_unlock(&hvc_structs_lock);
656 poll_mask |= HVC_POLL_READ;
659 if (poll_mask & HVC_POLL_QUICK) {
663 set_current_state(TASK_INTERRUPTIBLE);
668 msleep_interruptible(TIMEOUT);
670 __set_current_state(TASK_RUNNING);
671 } while (!kthread_should_stop());
676 static struct tty_operations hvc_ops = {
680 .hangup = hvc_hangup,
681 .unthrottle = hvc_unthrottle,
682 .write_room = hvc_write_room,
683 .chars_in_buffer = hvc_chars_in_buffer,
686 /* callback when the kboject ref count reaches zero. */
687 static void destroy_hvc_struct(struct kobject *kobj)
689 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
692 spin_lock(&hvc_structs_lock);
694 spin_lock_irqsave(&hp->lock, flags);
695 list_del(&(hp->next));
696 spin_unlock_irqrestore(&hp->lock, flags);
698 spin_unlock(&hvc_structs_lock);
703 static struct kobj_type hvc_kobj_type = {
704 .release = destroy_hvc_struct,
707 static int __devinit hvc_probe(
709 const struct vio_device_id *id)
711 struct hvc_struct *hp;
714 /* probed with invalid parameters. */
718 hp = kmalloc(sizeof(*hp), GFP_KERNEL);
722 memset(hp, 0x00, sizeof(*hp));
723 hp->vtermno = dev->unit_address;
725 hp->vdev->dev.driver_data = hp;
728 kobject_init(&hp->kobj);
729 hp->kobj.ktype = &hvc_kobj_type;
731 spin_lock_init(&hp->lock);
732 spin_lock(&hvc_structs_lock);
736 * see if this vterm id matches one registered for console.
738 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
739 if (vtermnos[i] == hp->vtermno)
742 /* no matching slot, just use a counter */
743 if (i >= MAX_NR_HVC_CONSOLES)
748 list_add_tail(&(hp->next), &hvc_structs);
749 spin_unlock(&hvc_structs_lock);
754 static int __devexit hvc_remove(struct vio_dev *dev)
756 struct hvc_struct *hp = dev->dev.driver_data;
758 struct kobject *kobjp;
759 struct tty_struct *tty;
761 spin_lock_irqsave(&hp->lock, flags);
765 if (hp->index < MAX_NR_HVC_CONSOLES)
766 vtermnos[hp->index] = -1;
768 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
770 spin_unlock_irqrestore(&hp->lock, flags);
773 * We 'put' the instance that was grabbed when the kobject instance
774 * was intialized using kobject_init(). Let the last holder of this
775 * kobject cause it to be removed, which will probably be the tty_hangup
781 * This function call will auto chain call hvc_hangup. The tty should
782 * always be valid at this time unless a simultaneous tty close already
783 * cleaned up the hvc_struct.
790 char hvc_driver_name[] = "hvc_console";
792 static struct vio_device_id hvc_driver_table[] __devinitdata= {
793 {"serial", "hvterm1"},
796 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
798 static struct vio_driver hvc_vio_driver = {
799 .name = hvc_driver_name,
800 .id_table = hvc_driver_table,
802 .remove = hvc_remove,
805 /* Driver initialization. Follow console initialization. This is where the TTY
806 * interfaces start to become available. */
807 int __init hvc_init(void)
811 /* We need more than hvc_count adapters due to hotplug additions. */
812 hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
816 hvc_driver->owner = THIS_MODULE;
817 hvc_driver->devfs_name = "hvc/";
818 hvc_driver->driver_name = "hvc";
819 hvc_driver->name = "hvc";
820 hvc_driver->major = HVC_MAJOR;
821 hvc_driver->minor_start = HVC_MINOR;
822 hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
823 hvc_driver->init_termios = tty_std_termios;
824 hvc_driver->flags = TTY_DRIVER_REAL_RAW;
825 tty_set_operations(hvc_driver, &hvc_ops);
827 if (tty_register_driver(hvc_driver))
828 panic("Couldn't register hvc console driver\n");
830 /* Always start the kthread because there can be hotplug vty adapters
832 hvc_task = kthread_run(khvcd, NULL, "khvcd");
833 if (IS_ERR(hvc_task)) {
834 panic("Couldn't create kthread for console.\n");
835 put_tty_driver(hvc_driver);
839 /* Register as a vio device to receive callbacks */
840 rc = vio_register_driver(&hvc_vio_driver);
844 module_init(hvc_init);
846 /* This isn't particularily necessary due to this being a console driver
847 * but it is nice to be thorough.
849 static void __exit hvc_exit(void)
851 kthread_stop(hvc_task);
853 vio_unregister_driver(&hvc_vio_driver);
854 tty_unregister_driver(hvc_driver);
855 /* return tty_struct instances allocated in hvc_init(). */
856 put_tty_driver(hvc_driver);
857 unregister_console(&hvc_con_driver);
859 module_exit(hvc_exit);