hvc_console.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 880 行 · 第 1/2 页

		hvc_kick();

	return written;
}

/*
 * This is actually a contract between the driver and the tty layer outlining
 * how much write room the driver can guarentee 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 N_OUTBUF - 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;
}

#define HVC_POLL_READ	0x00000001
#define HVC_POLL_WRITE	0x00000002
#define HVC_POLL_QUICK	0x00000004

static 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 interrupt driven and aren't throttled, we always
	 * request a reschedule
	 */
	if (hp->irq == NO_IRQ)
		poll_mask |= HVC_POLL_READ;

	/* Read data if any */
	for (;;) {
		int count = N_INBUF;
		if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
			count = TTY_FLIPBUF_SIZE - tty->flip.count;

		/* If flip is full, just reschedule a later read */
		if (count == 0) {
			poll_mask |= HVC_POLL_READ;
			break;
		}

		n = hvc_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);
			}
			break;
		}
		for (i = 0; i < n; ++i) {
#ifdef CONFIG_MAGIC_SYSRQ
			/* Handle the SysRq Hack */
			if (buf[i] == '\x0f') {	/* ^O -- should support a sequence */
				sysrq_pressed = 1;
				continue;
			} else if (sysrq_pressed) {
				handle_sysrq(buf[i], NULL, tty);
				sysrq_pressed = 0;
				continue;
			}
#endif /* CONFIG_MAGIC_SYSRQ */
			tty_insert_flip_char(tty, buf[i], 0);
		}

		if (tty->flip.count)
			tty_schedule_flip(tty);

		/*
		 * Account for the total amount read in one loop, and if above
		 * 64 bytes, we do a quick schedule loop to let the tty grok the
		 * data and eventually throttle us.
		 */
		read_total += n;
		if (read_total >= 64) {
			poll_mask |= HVC_POLL_QUICK;
			break;
		}
	}
 throttled:
	/* Wakeup write queue if necessary */
	if (hp->do_wakeup) {
		hp->do_wakeup = 0;
		tty_wakeup(tty);
	}
 bail:
	spin_unlock_irqrestore(&hp->lock, flags);

	return poll_mask;
}

#if defined(CONFIG_XMON) && defined(CONFIG_SMP)
extern cpumask_t cpus_in_xmon;
#else
static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
#endif

/*
 * This kthread is either polling or interrupt driven.  This is determined by
 * calling hvc_poll() who determines whether a console adapter support
 * interrupts.
 */
int khvcd(void *unused)
{
	int poll_mask;
	struct hvc_struct *hp;

	__set_current_state(TASK_RUNNING);
	do {
		poll_mask = 0;
		hvc_kicked = 0;
		wmb();
		if (cpus_empty(cpus_in_xmon)) {
			spin_lock(&hvc_structs_lock);
			list_for_each_entry(hp, &hvc_structs, next) {
				/*hp = list_entry(node, struct hvc_struct, * 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_QUICK) {
			yield();
			continue;
		}
		set_current_state(TASK_INTERRUPTIBLE);
		if (!hvc_kicked) {
			if (poll_mask == 0)
				schedule();
			else
				schedule_timeout(TIMEOUT);
		}
		__set_current_state(TASK_RUNNING);
	} while (!kthread_should_stop());

	return 0;
}

static 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,
};

char hvc_driver_name[] = "hvc_console";

static struct vio_device_id hvc_driver_table[] __devinitdata= {
	{"serial", "hvterm1"},
	{ 0, }
};
MODULE_DEVICE_TABLE(vio, hvc_driver_table);

/* callback when the kboject ref count reaches zero. */
static void destroy_hvc_struct(struct kobject *kobj)
{
	struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
	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);
}

static struct kobj_type hvc_kobj_type = {
	.release = destroy_hvc_struct,
};

static int __devinit hvc_probe(
		struct vio_dev *dev,
		const struct vio_device_id *id)
{
	struct hvc_struct *hp;

	/* probed with invalid parameters. */
	if (!dev || !id)
		return -EPERM;

	hp = kmalloc(sizeof(*hp), GFP_KERNEL);
	if (!hp)
		return -ENOMEM;

	memset(hp, 0x00, sizeof(*hp));
	hp->vtermno = dev->unit_address;
	hp->vdev = dev;
	hp->vdev->dev.driver_data = hp;
	hp->irq = dev->irq;

	kobject_init(&hp->kobj);
	hp->kobj.ktype = &hvc_kobj_type;

	hp->lock = SPIN_LOCK_UNLOCKED;
	spin_lock(&hvc_structs_lock);
	hp->index = ++hvc_count;
	list_add_tail(&(hp->next), &hvc_structs);
	spin_unlock(&hvc_structs_lock);

	return 0;
}

static int __devexit hvc_remove(struct vio_dev *dev)
{
	struct hvc_struct *hp = dev->dev.driver_data;
	unsigned long flags;
	struct kobject *kobjp;
	struct tty_struct *tty;

	spin_lock_irqsave(&hp->lock, flags);
	tty = hp->tty;
	kobjp = &hp->kobj;

	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 kobject instance
	 * was intialized using kobject_init().  Let the last holder of this
	 * kobject cause it to be removed, which will probably be the tty_hangup
	 * below.
	 */
	kobject_put(kobjp);

	/*
	 * 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;
}

static struct vio_driver hvc_vio_driver = {
	.name		= hvc_driver_name,
	.id_table	= hvc_driver_table,
	.probe		= hvc_probe,
	.remove		= hvc_remove,
};

/* Driver initialization.  Follow console initialization.  This is where the TTY
 * interfaces start to become available. */
int __init hvc_init(void)
{
	int rc;

	/* We need more than num_vterms adapters due to hotplug additions. */
	hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
	/* hvc_driver = alloc_tty_driver(num_vterms); */
	if (!hvc_driver)
		return -ENOMEM;

	hvc_driver->owner = THIS_MODULE;
	hvc_driver->devfs_name = "hvc/";
	hvc_driver->driver_name = "hvc";
	hvc_driver->name = "hvc";
	hvc_driver->major = HVC_MAJOR;
	hvc_driver->minor_start = HVC_MINOR;
	hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
	hvc_driver->init_termios = tty_std_termios;
	hvc_driver->flags = TTY_DRIVER_REAL_RAW;
	tty_set_operations(hvc_driver, &hvc_ops);

	if (tty_register_driver(hvc_driver))
		panic("Couldn't register hvc console driver\n");

	/* 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)) {
		panic("Couldn't create kthread for console.\n");
		put_tty_driver(hvc_driver);
		return -EIO;
	}

	/* Register as a vio device to receive callbacks */
	rc = vio_register_driver(&hvc_vio_driver);

	return rc;
}

/* This isn't particularily necessary due to this being a console driver but it
 * is nice to be thorough */
static void __exit hvc_exit(void)
{
	kthread_stop(hvc_task);

	vio_unregister_driver(&hvc_vio_driver);
	tty_unregister_driver(hvc_driver);
	/* return tty_struct instances allocated in hvc_init(). */
	put_tty_driver(hvc_driver);
}

/*
 * Console APIs, NOT TTY.  These APIs are available immediately when
 * hvc_console_setup() finds adapters.
 */

/*
 * 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 the appear after early console init.
 */
int hvc_instantiate(uint32_t vtermno, int index)
{
	if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
		return -1;

	if (vtermnos[index] != -1)
		return -1;

	vtermnos[index] = vtermno;
	return 0;
}

void hvc_console_print(struct console *co, const char *b, unsigned count)
{
	char c[16] __ALIGNED__;
	unsigned i = 0, n = 0;
	int r, donecr = 0;

	/* Console access attempt outside of acceptable console range. */
	if (co->index >= MAX_NR_HVC_CONSOLES)
		return;

	/* This console adapter was removed so it is not useable. */
	if (vtermnos[co->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 = hvc_put_chars(vtermnos[co->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)
{
	*index = c->index;
	return hvc_driver;
}

static int __init hvc_console_setup(struct console *co, char *options)
{
	return 0;
}

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.  Preceeds driver initialization. */
static int __init hvc_console_init(void)
{
	int i;

	for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
		vtermnos[i] = -1;
	num_vterms = hvc_find_vtys();
	register_console(&hvc_con_driver);
	return 0;
}
console_initcall(hvc_console_init);

module_init(hvc_init);
module_exit(hvc_exit);