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 <asm/uaccess.h>
42 #include <asm/hvconsole.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 * The Linux TTY code does not support dynamic addition of tty derived devices
58 * so we need to know how many tty devices we might need when space is allocated
59 * for the tty device. Since this driver supports hotplug of vty adapters we
60 * need to make sure we have enough allocated.
62 #define HVC_ALLOC_TTY_ADAPTERS 8
67 #define __ALIGNED__ __attribute__((__aligned__(8)))
69 static struct tty_driver *hvc_driver;
70 static struct task_struct *hvc_task;
72 /* Picks up late kicks after list walk but before schedule() */
73 static int hvc_kicked;
75 #ifdef CONFIG_MAGIC_SYSRQ
76 static int sysrq_pressed;
82 struct tty_struct *tty;
85 char outbuf[N_OUTBUF] __ALIGNED__;
90 struct list_head next;
91 struct kobject kobj; /* ref count & hvc_struct lifetime */
95 /* dynamic list of hvc_struct instances */
96 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
99 * Protect the list of hvc_struct instances from inserts and removals during
102 static DEFINE_SPINLOCK(hvc_structs_lock);
105 * This value is used to assign a tty->index value to a hvc_struct based
106 * upon order of exposure via hvc_probe(), when we can not match it to
107 * a console canidate registered with hvc_instantiate().
109 static int last_hvc = -1;
112 * Do not call this function with either the hvc_strucst_lock or the hvc_struct
113 * lock held. If successful, this function increments the kobject reference
114 * count against the target hvc_struct so it should be released when finished.
116 struct hvc_struct *hvc_get_by_index(int index)
118 struct hvc_struct *hp;
121 spin_lock(&hvc_structs_lock);
123 list_for_each_entry(hp, &hvc_structs, next) {
124 spin_lock_irqsave(&hp->lock, flags);
125 if (hp->index == index) {
126 kobject_get(&hp->kobj);
127 spin_unlock_irqrestore(&hp->lock, flags);
128 spin_unlock(&hvc_structs_lock);
131 spin_unlock_irqrestore(&hp->lock, flags);
135 spin_unlock(&hvc_structs_lock);
141 * Initial console vtermnos for console API usage prior to full console
142 * initialization. Any vty adapter outside this range will not have usable
143 * console interfaces but can still be used as a tty device. This has to be
144 * static because kmalloc will not work during early console init.
146 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES];
148 /* Used for accounting purposes */
149 static int num_vterms = 0;
152 * Console APIs, NOT TTY. These APIs are available immediately when
153 * hvc_console_setup() finds adapters.
156 void hvc_console_print(struct console *co, const char *b, unsigned count)
158 char c[16] __ALIGNED__;
159 unsigned i = 0, n = 0;
162 /* Console access attempt outside of acceptable console range. */
163 if (co->index >= MAX_NR_HVC_CONSOLES)
166 /* This console adapter was removed so it is not useable. */
167 if (vtermnos[co->index] < 0)
170 while (count > 0 || i > 0) {
171 if (count > 0 && i < sizeof(c)) {
172 if (b[n] == '\n' && !donecr) {
181 r = hvc_put_chars(vtermnos[co->index], c, i);
183 /* throw away chars on error */
194 static struct tty_driver *hvc_console_device(struct console *c, int *index)
200 static int __init hvc_console_setup(struct console *co, char *options)
205 struct console hvc_con_driver = {
207 .write = hvc_console_print,
208 .device = hvc_console_device,
209 .setup = hvc_console_setup,
210 .flags = CON_PRINTBUFFER,
214 /* Early console initialization. Preceeds driver initialization. */
215 static int __init hvc_console_init(void)
219 for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
221 num_vterms = hvc_find_vtys();
222 register_console(&hvc_con_driver);
225 console_initcall(hvc_console_init);
228 * hvc_instantiate() is an early console discovery method which locates
229 * consoles * prior to the vio subsystem discovering them. Hotplugged
230 * vty adapters do NOT get an hvc_instantiate() callback since they
231 * appear after early console init.
233 int hvc_instantiate(uint32_t vtermno, int index)
235 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
238 if (vtermnos[index] != -1)
241 vtermnos[index] = vtermno;
243 /* reserve all indices upto and including this index */
244 if (last_hvc < index)
250 /* Wake the sleeping khvcd */
251 static void hvc_kick(void)
254 wake_up_process(hvc_task);
257 static int hvc_poll(struct hvc_struct *hp);
260 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
261 * In this case the console is poll driven.
263 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
265 /* if hvc_poll request a repoll, then kick the hvcd thread */
266 if (hvc_poll(dev_instance))
271 static void hvc_unthrottle(struct tty_struct *tty)
277 * The TTY interface won't be used until after the vio layer has exposed the vty
278 * adapter to the kernel.
280 static int hvc_open(struct tty_struct *tty, struct file * filp)
282 struct hvc_struct *hp;
286 struct kobject *kobjp;
288 /* Auto increments kobject reference if found. */
289 if (!(hp = hvc_get_by_index(tty->index))) {
290 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
294 spin_lock_irqsave(&hp->lock, flags);
295 /* Check and then increment for fast path open. */
296 if (hp->count++ > 0) {
297 spin_unlock_irqrestore(&hp->lock, flags);
300 } /* else count == 0 */
302 tty->driver_data = hp;
304 /* Save for request_irq outside of spin_lock. */
307 hp->irq_requested = 1;
311 spin_unlock_irqrestore(&hp->lock, flags);
312 /* check error, fallback to non-irq */
314 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
317 * If the request_irq() fails and we return an error. The tty layer
318 * will call hvc_close() after a failed open but we don't want to clean
319 * up there so we'll clean up here and clear out the previously set
320 * tty fields and return the kobject reference.
323 spin_lock_irqsave(&hp->lock, flags);
325 hp->irq_requested = 0;
326 spin_unlock_irqrestore(&hp->lock, flags);
327 tty->driver_data = NULL;
329 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
331 /* Force wakeup of the polling thread */
337 static void hvc_close(struct tty_struct *tty, struct file * filp)
339 struct hvc_struct *hp;
340 struct kobject *kobjp;
344 if (tty_hung_up_p(filp))
348 * No driver_data means that this close was issued after a failed
349 * hvc_open by the tty layer's release_dev() function and we can just
350 * exit cleanly because the kobject reference wasn't made.
352 if (!tty->driver_data)
355 hp = tty->driver_data;
356 spin_lock_irqsave(&hp->lock, flags);
359 if (--hp->count == 0) {
360 if (hp->irq_requested)
362 hp->irq_requested = 0;
364 /* We are done with the tty pointer now. */
366 spin_unlock_irqrestore(&hp->lock, flags);
369 * Chain calls chars_in_buffer() and returns immediately if
370 * there is no buffered data otherwise sleeps on a wait queue
371 * waking periodically to check chars_in_buffer().
373 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
380 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
381 hp->vtermno, hp->count);
382 spin_unlock_irqrestore(&hp->lock, flags);
388 static void hvc_hangup(struct tty_struct *tty)
390 struct hvc_struct *hp = tty->driver_data;
394 struct kobject *kobjp;
399 spin_lock_irqsave(&hp->lock, flags);
402 * The N_TTY line discipline has problems such that in a close vs
403 * open->hangup case this can be called after the final close so prevent
404 * that from happening for now.
406 if (hp->count <= 0) {
407 spin_unlock_irqrestore(&hp->lock, flags);
412 temp_open_count = hp->count;
416 if (hp->irq_requested)
417 /* Saved for use outside of spin_lock. */
419 hp->irq_requested = 0;
420 spin_unlock_irqrestore(&hp->lock, flags);
423 while(temp_open_count) {
430 * Push buffered characters whether they were just recently buffered or waiting
431 * on a blocked hypervisor. Call this function with hp->lock held.
433 static void hvc_push(struct hvc_struct *hp)
437 n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
441 /* throw away output on error; this happens when
442 there is no session connected to the vterm. */
446 if (hp->n_outbuf > 0)
447 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
452 static inline int __hvc_write_kernel(struct hvc_struct *hp,
453 const unsigned char *buf, int count)
456 int rsize, written = 0;
458 spin_lock_irqsave(&hp->lock, flags);
460 /* Push pending writes */
461 if (hp->n_outbuf > 0)
464 while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
467 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
470 hp->n_outbuf += rsize;
474 spin_unlock_irqrestore(&hp->lock, flags);
478 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
480 struct hvc_struct *hp = tty->driver_data;
483 /* This write was probably executed during a tty close. */
490 written = __hvc_write_kernel(hp, buf, count);
493 * Racy, but harmless, kick thread if there is still pending data.
494 * There really is nothing wrong with kicking the thread, even if there
495 * is no buffered data.
504 * This is actually a contract between the driver and the tty layer outlining
505 * how much write room the driver can guarentee will be sent OR BUFFERED. This
506 * driver MUST honor the return value.
508 static int hvc_write_room(struct tty_struct *tty)
510 struct hvc_struct *hp = tty->driver_data;
515 return N_OUTBUF - hp->n_outbuf;
518 static int hvc_chars_in_buffer(struct tty_struct *tty)
520 struct hvc_struct *hp = tty->driver_data;
527 #define HVC_POLL_READ 0x00000001
528 #define HVC_POLL_WRITE 0x00000002
529 #define HVC_POLL_QUICK 0x00000004
531 static int hvc_poll(struct hvc_struct *hp)
533 struct tty_struct *tty;
534 int i, n, poll_mask = 0;
535 char buf[N_INBUF] __ALIGNED__;
539 spin_lock_irqsave(&hp->lock, flags);
541 /* Push pending writes */
542 if (hp->n_outbuf > 0)
544 /* Reschedule us if still some write pending */
545 if (hp->n_outbuf > 0)
546 poll_mask |= HVC_POLL_WRITE;
548 /* No tty attached, just skip */
553 /* Now check if we can get data (are we throttled ?) */
554 if (test_bit(TTY_THROTTLED, &tty->flags))
557 /* If we aren't interrupt driven and aren't throttled, we always
558 * request a reschedule
560 if (hp->irq == NO_IRQ)
561 poll_mask |= HVC_POLL_READ;
563 /* Read data if any */
566 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
567 count = TTY_FLIPBUF_SIZE - tty->flip.count;
569 /* If flip is full, just reschedule a later read */
571 poll_mask |= HVC_POLL_READ;
575 n = hvc_get_chars(hp->vtermno, buf, count);
577 /* Hangup the tty when disconnected from host */
579 spin_unlock_irqrestore(&hp->lock, flags);
581 spin_lock_irqsave(&hp->lock, flags);
585 for (i = 0; i < n; ++i) {
586 #ifdef CONFIG_MAGIC_SYSRQ
587 if (hp->index == hvc_con_driver.index) {
588 /* Handle the SysRq Hack */
589 /* XXX should support a sequence */
590 if (buf[i] == '\x0f') { /* ^O */
593 } else if (sysrq_pressed) {
594 handle_sysrq(buf[i], NULL, tty);
599 #endif /* CONFIG_MAGIC_SYSRQ */
600 tty_insert_flip_char(tty, buf[i], 0);
604 tty_schedule_flip(tty);
607 * Account for the total amount read in one loop, and if above
608 * 64 bytes, we do a quick schedule loop to let the tty grok
609 * the data and eventually throttle us.
612 if (read_total >= 64) {
613 poll_mask |= HVC_POLL_QUICK;
618 /* Wakeup write queue if necessary */
624 spin_unlock_irqrestore(&hp->lock, flags);
629 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
630 extern cpumask_t cpus_in_xmon;
632 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
636 * This kthread is either polling or interrupt driven. This is determined by
637 * calling hvc_poll() who determines whether a console adapter support
640 int khvcd(void *unused)
643 struct hvc_struct *hp;
645 __set_current_state(TASK_RUNNING);
650 if (cpus_empty(cpus_in_xmon)) {
651 spin_lock(&hvc_structs_lock);
652 list_for_each_entry(hp, &hvc_structs, next) {
653 /*hp = list_entry(node, struct hvc_struct, * next); */
654 poll_mask |= hvc_poll(hp);
656 spin_unlock(&hvc_structs_lock);
658 poll_mask |= HVC_POLL_READ;
661 if (poll_mask & HVC_POLL_QUICK) {
665 set_current_state(TASK_INTERRUPTIBLE);
670 msleep_interruptible(TIMEOUT);
672 __set_current_state(TASK_RUNNING);
673 } while (!kthread_should_stop());
678 static struct tty_operations hvc_ops = {
682 .hangup = hvc_hangup,
683 .unthrottle = hvc_unthrottle,
684 .write_room = hvc_write_room,
685 .chars_in_buffer = hvc_chars_in_buffer,
688 /* callback when the kboject ref count reaches zero. */
689 static void destroy_hvc_struct(struct kobject *kobj)
691 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
694 spin_lock(&hvc_structs_lock);
696 spin_lock_irqsave(&hp->lock, flags);
697 list_del(&(hp->next));
698 spin_unlock_irqrestore(&hp->lock, flags);
700 spin_unlock(&hvc_structs_lock);
705 static struct kobj_type hvc_kobj_type = {
706 .release = destroy_hvc_struct,
709 static int __devinit hvc_probe(
711 const struct vio_device_id *id)
713 struct hvc_struct *hp;
716 /* probed with invalid parameters. */
720 hp = kmalloc(sizeof(*hp), GFP_KERNEL);
724 memset(hp, 0x00, sizeof(*hp));
725 hp->vtermno = dev->unit_address;
727 hp->vdev->dev.driver_data = hp;
730 kobject_init(&hp->kobj);
731 hp->kobj.ktype = &hvc_kobj_type;
733 spin_lock_init(&hp->lock);
734 spin_lock(&hvc_structs_lock);
738 * see if this vterm id matches one registered for console.
740 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
741 if (vtermnos[i] == hp->vtermno)
744 /* no matching slot, just use a counter */
745 if (i >= MAX_NR_HVC_CONSOLES)
750 list_add_tail(&(hp->next), &hvc_structs);
751 spin_unlock(&hvc_structs_lock);
756 static int __devexit hvc_remove(struct vio_dev *dev)
758 struct hvc_struct *hp = dev->dev.driver_data;
760 struct kobject *kobjp;
761 struct tty_struct *tty;
763 spin_lock_irqsave(&hp->lock, flags);
767 if (hp->index < MAX_NR_HVC_CONSOLES)
768 vtermnos[hp->index] = -1;
770 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
772 spin_unlock_irqrestore(&hp->lock, flags);
775 * We 'put' the instance that was grabbed when the kobject instance
776 * was intialized using kobject_init(). Let the last holder of this
777 * kobject cause it to be removed, which will probably be the tty_hangup
783 * This function call will auto chain call hvc_hangup. The tty should
784 * always be valid at this time unless a simultaneous tty close already
785 * cleaned up the hvc_struct.
792 char hvc_driver_name[] = "hvc_console";
794 static struct vio_device_id hvc_driver_table[] __devinitdata= {
795 {"serial", "hvterm1"},
798 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
800 static struct vio_driver hvc_vio_driver = {
801 .name = hvc_driver_name,
802 .id_table = hvc_driver_table,
804 .remove = hvc_remove,
807 /* Driver initialization. Follow console initialization. This is where the TTY
808 * interfaces start to become available. */
809 int __init hvc_init(void)
813 /* We need more than num_vterms adapters due to hotplug additions. */
814 hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
815 /* hvc_driver = alloc_tty_driver(num_vterms); */
819 hvc_driver->owner = THIS_MODULE;
820 hvc_driver->devfs_name = "hvc/";
821 hvc_driver->driver_name = "hvc";
822 hvc_driver->name = "hvc";
823 hvc_driver->major = HVC_MAJOR;
824 hvc_driver->minor_start = HVC_MINOR;
825 hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
826 hvc_driver->init_termios = tty_std_termios;
827 hvc_driver->flags = TTY_DRIVER_REAL_RAW;
828 tty_set_operations(hvc_driver, &hvc_ops);
830 if (tty_register_driver(hvc_driver))
831 panic("Couldn't register hvc console driver\n");
833 /* Always start the kthread because there can be hotplug vty adapters
835 hvc_task = kthread_run(khvcd, NULL, "khvcd");
836 if (IS_ERR(hvc_task)) {
837 panic("Couldn't create kthread for console.\n");
838 put_tty_driver(hvc_driver);
842 /* Register as a vio device to receive callbacks */
843 rc = vio_register_driver(&hvc_vio_driver);
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 vio_unregister_driver(&hvc_vio_driver);
857 tty_unregister_driver(hvc_driver);
858 /* return tty_struct instances allocated in hvc_init(). */
859 put_tty_driver(hvc_driver);
860 unregister_console(&hvc_con_driver);
862 module_exit(hvc_exit);