/*
* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
* Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
* Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
* Copyright (C) 2004 IBM Corporation
*
* Additional Author(s):
* Ryan S. Arnold <rsa@us.ibm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/console.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/kbd_kern.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/major.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <asm/uaccess.h>
#include "hvc_console.h"
#define HVC_MAJOR 229
#define HVC_MINOR 0
/*
* Wait this long per iteration while trying to push buffered data to the
* hypervisor before allowing the tty to complete a close operation.
*/
#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
/*
* These sizes are most efficient for vio, because they are the
* native transfer size. We could make them selectable in the
* future to better deal with backends that want other buffer sizes.
*/
#define N_OUTBUF 16
#define N_INBUF 16
#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
static struct tty_driver *hvc_driver;
static struct task_struct *hvc_task;
/* Picks up late kicks after list walk but before schedule() */
static int hvc_kicked;
static int hvc_init(void);
#ifdef CONFIG_MAGIC_SYSRQ
static int sysrq_pressed;
#endif
/* dynamic list of hvc_struct instances */
static LIST_HEAD(hvc_structs);
/*
* Protect the list of hvc_struct instances from inserts and removals during
* list traversal.
*/
static DEFINE_SPINLOCK(hvc_structs_lock);
/*
* This value is used to assign a tty->index value to a hvc_struct based
* upon order of exposure via hvc_probe(), when we can not match it to
* a console candidate registered with hvc_instantiate().
*/
static int last_hvc = -1;
/*
* Do not call this function with either the hvc_structs_lock or the hvc_struct
* lock held. If successful, this function increments the kref reference
* count against the target hvc_struct so it should be released when finished.
*/
static struct hvc_struct *hvc_get_by_index(int index)
{
struct hvc_struct *hp;
unsigned long flags;
spin_lock(&hvc_structs_lock);
list_for_each_entry(hp, &hvc_structs, next) {
spin_lock_irqsave(&hp->lock, flags);
if (hp->index == index) {
kref_get(&hp->kref);
spin_unlock_irqrestore(&hp->lock, flags);
spin_unlock(&hvc_structs_lock);
return hp;
}
spin_unlock_irqrestore(&hp->lock, flags);
}
hp = NULL;
spin_unlock(&hvc_structs_lock);
return hp;
}
/*
* Initial console vtermnos for console API usage prior to full console
* initialization. Any vty adapter outside this range will not have usable
* console interfaces but can still be used as a tty device. This has to be
* static because kmalloc will not work during early console init.
*/
static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
{[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
/*
* Console APIs, NOT TTY. These APIs are available immediately when
* hvc_console_setup() finds adapters.
*/
static void hvc_console_print(struct console *co, const char *b,
unsigned count)
{
char c[N_OUTBUF] __ALIGNED__;
unsigned i = 0, n = 0;
int r, donecr = 0, index = co->index;
/* Console access attempt outside of acceptable console range. */
if (index >= MAX_NR_HVC_CONSOLES)
return;
/* This console adapter was removed so it is not usable. */
if (vtermnos[index] < 0)
return;
while (count > 0 || i > 0) {
if (count > 0 && i < sizeof(c)) {
if (b[n] == '\n' && !donecr) {
c[i++] = '\r';
donecr = 1;
} else {
c[i++] = b[n++];
donecr = 0;
--count;
}
} else {
r = cons_ops[index]->put_chars(vtermnos[index], c, i);
if (r < 0) {
/* throw away chars on error */
i = 0;
} else if (r > 0) {
i -= r;
if (i > 0)
memmove(c, c+r, i);
}
}
}
}
static struct tty_driver *hvc_console_device(struct console *c, int *index)
{
if (vtermnos[c->index] == -1)
return NULL;
*index = c->index;
return hvc_driver;
}
static int __init hvc_console_setup(struct console *co, char *options)
{
if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
return -ENODEV;
if (vtermnos[co->index] == -1)
return -ENODEV;
return 0;
}
static struct console hvc_con_driver = {
.name = "hvc",
.write = hvc_console_print,
.device = hvc_console_device,
.setup = hvc_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
};
/*
* Early console initialization. Precedes driver initialization.
*
* (1) we are first, and the user specified another driver
* -- index will remain -1
* (2) we are first and the user specified no driver
* -- index will be set to 0, then we will fail setup.
* (3) we are first and the user specified our driver
* -- index will be set to user specified driver, and we will fail
* (4) we are after driver, and this initcall will register us
* -- if the user didn't specify a driver then the console will match
*
* Note that for cases 2 and 3, we will match later when the io driver
* calls hvc_instantiate() and call register again.
*/
static int __init hvc_console_init(void)
{
register_console(&hvc_con_driver);
return 0;
}
console_initcall(hvc_console_init);
/* callback when the kboject ref count reaches zero. */
static void destroy_hvc_struct(struct kref *kref)
{
struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
unsigned long flags;
spin_lock(&hvc_structs_lock);
spin_lock_irqsave(&hp->lock, flags);
list_del(&(hp->next));
spin_unlock_irqrestore(&hp->lock, flags);
spin_unlock(&hvc_structs_lock);
kfree(hp);
}
/*
* hvc_instantiate() is an early console discovery method which locates
* consoles * prior to the vio subsystem discovering them. Hotplugged
* vty adapters do NOT get an hvc_instantiate() callback since they
* appear after early console init.
*/
int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
{
struct hvc_struct *hp;
if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
return -1;
if (vtermnos[index] != -1)
return -1;
/* make sure no no tty has been registered in this index */
hp = hvc_get_by_index(index);
if (hp) {
kref_put(&hp->kref, destroy_hvc_struct);
return -1;
}
vtermnos[index] = vtermno;
cons_ops[index] = ops;
/* reserve all indices up to and including this index */
if (last_hvc < index)
last_hvc = index;
/* if this index is what the user requested, then register
* now (setup won't fail at this point). It's ok to just
* call register again if previously .setup failed.
*/
if (index == hvc_con_driver.index)
register_console(&hvc_con_driver);
return 0;
}
EXPORT_SYMBOL_GPL(hvc_instantiate);
/* Wake the sleeping khvcd */
void hvc_kick(void)
{
hvc_kicked = 1;
wake_up_process(hvc_task);
}
EXPORT_SYMBOL_GPL(hvc_kick);
static void hvc_unthrottle(struct tty_struct *tty)
{
hvc_kick();
}
/*
* The TTY interface won't be used until after the vio layer has exposed the vty
* adapter to the kernel.
*/
static int hvc_open(struct tty_struct *tty, struct file * filp)
{
struct hvc_struct *hp;
unsigned long flags;
int rc = 0;
/* Auto increments kref reference if found. */
if (!(hp = hvc_get_by_index(tty->index)))
return -ENODEV;
spin_lock_irqsave(&hp->lock, flags);
/* Check and then increment for fast path open. */
if (hp->count++ > 0) {
spin_unlock_irqrestore(&hp->lock, flags);
hvc_kick();
return 0;
} /* else count == 0 */
tty->driver_data = hp;
tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
hp->tty = tty;
if (hp->ops->notifier_add)
rc = hp->ops->notifier_add(hp, hp->data);
spin_unlock_irqrestore(&hp->lock, flags);
/*
* If the notifier fails we return an error. The tty layer
* will call hvc_close() after a failed open but we don't want to clean
* up there so we'll clean up here and clear out the previously set
* tty fields and return the kref reference.
*/
if (rc) {
spin_lock_irqsave(&hp->lock, flags);
hp->tty = NULL;
spin_unlock_irqrestore(&hp->lock, flags);
tty->driver_data = NULL;
kref_put(&hp->kref, destroy_hvc_struct);
printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
}
/* Force wakeup of the polling thread */
hvc_kick();
return rc;
}
static void hvc_close(struct tty_struct *tty, struct file * filp)
{
struct hvc_struct *hp;
unsigned long flags;
if (tty_hung_up_p(filp))
return;
/*
* No driver_data means that this close was issued after a failed
* hvc_open by the tty layer's release_dev() function and we can just
* exit cleanly because the kref reference wasn't made.
*/
if (!tty->driver_data)
return;
hp = tty->driver_data;
spin_lock_irqsave(&hp->lock, flags);
if (--hp->count == 0) {
if (hp->ops->notifier_del)
hp->ops->notifier_del(hp, hp->data);
/* We are done with the tty pointer now. */
hp->tty = NULL;
spin_unlock_irqrestore(&hp->lock, flags);
/*
* Chain calls chars_in_buffer() and returns immediately if
* there is no buffered data otherwise sleeps on a wait queue
* waking periodically to check chars_in_buffer().
*/
tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
} else {
if (hp->count < 0)
printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
hp->vtermno, hp->count);
spin_unlock_irqrestore(&hp->lock, flags);
}
kref_put(&hp->kref, destroy_hvc_struct);
}
static void hvc_hangup(struct tty_struct *tty)
{
struct hvc_struct *hp = tty->driver_data;
unsigned long flags;
int temp_open_count;
if (!hp)
return;
spin_lock_irqsave(&hp->lock, flags);
/*
* The N_TTY line discipline has problems such that in a close vs
* open->hangup case this can be called after the final close so prevent
* that from happening for now.
*/
if (hp->count <= 0) {
spin_unlock_irqrestore(&hp->lock, flags);
return;
}
temp_open_count = hp->count;
hp->count = 0;
hp->n_outbuf = 0;
hp->tty = NULL;
if (hp->ops->notifier_del)
hp->ops->notifier_del(hp, hp->data);
spin_unlock_irqrestore(&hp->lock, flags);
while(temp_open_count) {
--temp_open_count;
kref_put(&hp->kref, destroy_hvc_struct);
}
}
/*
* Push buffered characters whether they were just recently buffered or waiting
* on a blocked hypervisor. Call this function with hp->lock held.
*/
static void hvc_push(struct hvc_struct *hp)
{
int n;
n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
if (n <= 0) {
if (n == 0) {
hp->do_wakeup = 1;
return;
}
/* throw away output on error; this happens when
there is no session connected to the vterm. */
hp->n_outbuf = 0;
} else
hp->n_outbuf -= n;
if (hp->n_outbuf > 0)
memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
else
hp->do_wakeup = 1;
}
static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
struct hvc_struct *hp = tty->driver_data;
unsigned long flags;
int rsize, written = 0;
/* This write was probably executed during a tty close. */
if (!hp)
return -EPIPE;
if (hp->count <= 0)
return -EIO;
spin_lock_irqsave(&hp->lock, flags);
/* Push pending writes */
if (hp->n_outbuf > 0)
hvc_push(hp);
while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
if (rsize > count)
rsize = count;
memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
count -= rsize;
buf += rsize;
hp->n_outbuf += rsize;
written += rsize;
hvc_push(hp);
}
spin_unlock_irqrestore(&hp->lock, flags);
/*
* Racy, but harmless, kick thread if there is still pending data.
*/
if (hp->n_outbuf)
hvc_kick();
return written;
}
/*
* This is actually a contract between the driver and the tty layer outlining
* how much write room the driver can guarantee will be sent OR BUFFERED. This
* driver MUST honor the return value.
*/
static int hvc_write_room(struct tty_struct *tty)
{
struct hvc_struct *hp = tty->driver_data;
if (!hp)
return -1;
return hp->outbuf_size - hp->n_outbuf;
}
static int hvc_chars_in_buffer(struct tty_struct *tty)
{
struct hvc_struct *hp = tty->driver_data;
if (!hp)
return -1;
return hp->n_outbuf;
}
/*
* timeout will vary between the MIN and MAX values defined here. By default
* and during console activity we will use a default MIN_TIMEOUT of 10. When
* the console is idle, we increase the timeout value on each pass through
* msleep until we reach the max. This may be noticeable as a brief (average
* one second) delay on the console before the console responds to input when
* there has been no input for some time.
*/
#define MIN_TIMEOUT (10)
#define MAX_TIMEOUT (2000)
static u32 timeout = MIN_TIMEOUT;
#define HVC_POLL_READ 0x00000001
#define HVC_POLL_WRITE 0x00000002
int hvc_poll(struct hvc_struct *hp)
{
struct tty_struct *tty;
int i, n, poll_mask = 0;
char buf[N_INBUF] __ALIGNED__;
unsigned long flags;
int read_total = 0;
spin_lock_irqsave(&hp->lock, flags);
/* Push pending writes */
if (hp->n_outbuf > 0)
hvc_push(hp);
/* Reschedule us if still some write pending */
if (hp->n_outbuf > 0)
poll_mask |= HVC_POLL_WRITE;
/* No tty attached, just skip */
tty = hp->tty;
if (tty == NULL)
goto bail;
/* Now check if we can get data (are we throttled ?) */
if (test_bit(TTY_THROTTLED, &tty->flags))
goto throttled;
/* If we aren't notifier driven and aren't throttled, we always
* request a reschedule
*/
if (!hp->irq_requested)
poll_mask |= HVC_POLL_READ;
/* Read data if any */
for (;;) {
int count = tty_buffer_request_room(tty, N_INBUF);
/* If flip is full, just reschedule a later read */
if (count == 0) {
poll_mask |= HVC_POLL_READ;
break;
}
n = hp->ops->get_chars(hp->vtermno, buf, count);
if (n <= 0) {
/* Hangup the tty when disconnected from host */
if (n == -EPIPE) {
spin_unlock_irqrestore(&hp->lock, flags);
tty_hangup(tty);
spin_lock_irqsave(&hp->lock, flags);
} else if ( n == -EAGAIN ) {
/*
* Some back-ends can only ensure a certain min
* num of bytes read, which may be > 'count'.
* Let the tty clear the flip buff to make room.
*/
poll_mask |= HVC_POLL_READ;
}
break;
}
for (i = 0; i < n; ++i) {
#ifdef CONFIG_MAGIC_SYSRQ
if (hp->index == hvc_con_driver.index) {
/* Handle the SysRq Hack */
/* XXX should support a sequence */
if (buf[i] == '\x0f') { /* ^O */
sysrq_pressed = 1;
continue;
} else if (sysrq_pressed) {
handle_sysrq(buf[i], tty);
sysrq_pressed = 0;
continue;
}
}
#endif /* CONFIG_MAGIC_SYSRQ */
tty_insert_flip_char(tty, buf[i], 0);
}
read_total += n;
}
throttled:
/* Wakeup write queue if necessary */
if (hp->do_wakeup) {
hp->do_wakeup = 0;
tty_wakeup(tty);
}
bail:
spin_unlock_irqrestore(&hp->lock, flags);
if (read_total) {
/* Activity is occurring, so reset the polling backoff value to
a minimum for performance. */
timeout = MIN_TIMEOUT;
tty_flip_buffer_push(tty);
}
return poll_mask;
}
EXPORT_SYMBOL_GPL(hvc_poll);
/*
* This kthread is either polling or interrupt driven. This is determined by
* calling hvc_poll() who determines whether a console adapter support
* interrupts.
*/
static int khvcd(void *unused)
{
int poll_mask;
struct hvc_struct *hp;
set_freezable();
__set_current_state(TASK_RUNNING);
do {
poll_mask = 0;
hvc_kicked = 0;
try_to_freeze();
wmb();
if (!cpus_are_in_xmon()) {
spin_lock(&hvc_structs_lock);
list_for_each_entry(hp, &hvc_structs, next) {
poll_mask |= hvc_poll(hp);
}
spin_unlock(&hvc_structs_lock);
} else
poll_mask |= HVC_POLL_READ;
if (hvc_kicked)
continue;
if (poll_mask & HVC_POLL_WRITE) {
yield();
continue;
}
set_current_state(TASK_INTERRUPTIBLE);
if (!hvc_kicked) {
if (poll_mask == 0)
schedule();
else {
if (timeout < MAX_TIMEOUT)
timeout += (timeout >> 6) + 1;
msleep_interruptible(timeout);
}
}
__set_current_state(TASK_RUNNING);
} while (!kthread_should_stop());
return 0;
}
static const struct tty_operations hvc_ops = {
.open = hvc_open,
.close = hvc_close,
.write = hvc_write,
.hangup = hvc_hangup,
.unthrottle = hvc_unthrottle,
.write_room = hvc_write_room,
.chars_in_buffer = hvc_chars_in_buffer,
};
struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int data,
struct hv_ops *ops, int outbuf_size)
{
struct hvc_struct *hp;
int i;
/* We wait until a driver actually comes along */
if (!hvc_driver) {
int err = hvc_init();
if (err)
return ERR_PTR(err);
}
hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
GFP_KERNEL);
if (!hp)
return ERR_PTR(-ENOMEM);
memset(hp, 0x00, sizeof(*hp));
hp->vtermno = vtermno;
hp->data = data;
hp->ops = ops;
hp->outbuf_size = outbuf_size;
hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
kref_init(&hp->kref);
spin_lock_init(&hp->lock);
spin_lock(&hvc_structs_lock);
/*
* find index to use:
* see if this vterm id matches one registered for console.
*/
for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
if (vtermnos[i] == hp->vtermno &&
cons_ops[i] == hp->ops)
break;
/* no matching slot, just use a counter */
if (i >= MAX_NR_HVC_CONSOLES)
i = ++last_hvc;
hp->index = i;
list_add_tail(&(hp->next), &hvc_structs);
spin_unlock(&hvc_structs_lock);
return hp;
}
EXPORT_SYMBOL_GPL(hvc_alloc);
int __devexit hvc_remove(struct hvc_struct *hp)
{
unsigned long flags;
struct tty_struct *tty;
spin_lock_irqsave(&hp->lock, flags);
tty = hp->tty;
if (hp->index < MAX_NR_HVC_CONSOLES)
vtermnos[hp->index] = -1;
/* Don't whack hp->irq because tty_hangup() will need to free the irq. */
spin_unlock_irqrestore(&hp->lock, flags);
/*
* We 'put' the instance that was grabbed when the kref instance
* was initialized using kref_init(). Let the last holder of this
* kref cause it to be removed, which will probably be the tty_hangup
* below.
*/
kref_put(&hp->kref, destroy_hvc_struct);
/*
* This function call will auto chain call hvc_hangup. The tty should
* always be valid at this time unless a simultaneous tty close already
* cleaned up the hvc_struct.
*/
if (tty)
tty_hangup(tty);
return 0;
}
/* Driver initialization: called as soon as someone uses hvc_alloc(). */
static int hvc_init(void)
{
struct tty_driver *drv;
int err;
/* We need more than hvc_count adapters due to hotplug additions. */
drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
if (!drv) {
err = -ENOMEM;
goto out;
}
drv->owner = THIS_MODULE;
drv->driver_name = "hvc";
drv->name = "hvc";
drv->major = HVC_MAJOR;
drv->minor_start = HVC_MINOR;
drv->type = TTY_DRIVER_TYPE_SYSTEM;
drv->init_termios = tty_std_termios;
drv->flags = TTY_DRIVER_REAL_RAW;
tty_set_operations(drv, &hvc_ops);
/* Always start the kthread because there can be hotplug vty adapters
* added later. */
hvc_task = kthread_run(khvcd, NULL, "khvcd");
if (IS_ERR(hvc_task)) {
printk(KERN_ERR "Couldn't create kthread for console.\n");
err = PTR_ERR(hvc_task);
goto put_tty;
}
err = tty_register_driver(drv);
if (err) {
printk(KERN_ERR "Couldn't register hvc console driver\n");
goto stop_thread;
}
/* FIXME: This mb() seems completely random. Remove it. */
mb();
hvc_driver = drv;
return 0;
put_tty:
put_tty_driver(hvc_driver);
stop_thread:
kthread_stop(hvc_task);
hvc_task = NULL;
out:
return err;
}
/* This isn't particularly necessary due to this being a console driver
* but it is nice to be thorough.
*/
static void __exit hvc_exit(void)
{
if (hvc_driver) {
kthread_stop(hvc_task);
tty_unregister_driver(hvc_driver);
/* return tty_struct instances allocated in hvc_init(). */
put_tty_driver(hvc_driver);
unregister_console(&hvc_con_driver);
}
}
module_exit(hvc_exit);
