sclp_vt220.c

linux-2.6.15.6

	if (count <= 0)
		return 0;
	overall_written = 0;
	spin_lock_irqsave(&sclp_vt220_lock, flags);
	do {
		/* Create a sclp output buffer if none exists yet */
		if (sclp_vt220_current_request == NULL) {
			while (list_empty(&sclp_vt220_empty)) {
				spin_unlock_irqrestore(&sclp_vt220_lock,
						       flags);
				if (in_interrupt())
					sclp_sync_wait();
				else
					wait_event(sclp_vt220_waitq,
						!list_empty(&sclp_vt220_empty));
				spin_lock_irqsave(&sclp_vt220_lock, flags);
			}
			page = (void *) sclp_vt220_empty.next;
			list_del((struct list_head *) page);
			sclp_vt220_current_request =
				sclp_vt220_initialize_page(page);
		}
		/* Try to write the string to the current request buffer */
		written = sclp_vt220_add_msg(sclp_vt220_current_request,
					     buf, count, convertlf);
		overall_written += written;
		if (written == count)
			break;
		/*
		 * Not all characters could be written to the current
		 * output buffer. Emit the buffer, create a new buffer
		 * and then output the rest of the string.
		 */
		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
		sclp_vt220_emit_current();
		spin_lock_irqsave(&sclp_vt220_lock, flags);
		buf += written;
		count -= written;
	} while (count > 0);
	/* Setup timer to output current console buffer after some time */
	if (sclp_vt220_current_request != NULL &&
	    !timer_pending(&sclp_vt220_timer) && do_schedule) {
		sclp_vt220_timer.function = sclp_vt220_timeout;
		sclp_vt220_timer.data = 0UL;
		sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
		add_timer(&sclp_vt220_timer);
	}
	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
	return overall_written;
}

/*
 * This routine is called by the kernel to write a series of
 * characters to the tty device.  The characters may come from
 * user space or kernel space.  This routine will return the
 * number of characters actually accepted for writing.
 */
static int
sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
	return __sclp_vt220_write(buf, count, 1, 0);
}

#define SCLP_VT220_SESSION_ENDED	0x01
#define	SCLP_VT220_SESSION_STARTED	0x80
#define SCLP_VT220_SESSION_DATA		0x00

/*
 * Called by the SCLP to report incoming event buffers.
 */
static void
sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
{
	char *buffer;
	unsigned int count;

	/* Ignore input if device is not open */
	if (sclp_vt220_tty == NULL)
		return;

	buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
	count = evbuf->length - sizeof(struct evbuf_header);

	switch (*buffer) {
	case SCLP_VT220_SESSION_ENDED:
	case SCLP_VT220_SESSION_STARTED:
		break;
	case SCLP_VT220_SESSION_DATA:
		/* Send input to line discipline */
		buffer++;
		count--;
		/* Prevent buffer overrun by discarding input. Note that
		 * because buffer_push works asynchronously, we cannot wait
		 * for the buffer to be emptied. */
		if (count + sclp_vt220_tty->flip.count > TTY_FLIPBUF_SIZE)
			count = TTY_FLIPBUF_SIZE - sclp_vt220_tty->flip.count;
		memcpy(sclp_vt220_tty->flip.char_buf_ptr, buffer, count);
		memset(sclp_vt220_tty->flip.flag_buf_ptr, TTY_NORMAL, count);
		sclp_vt220_tty->flip.char_buf_ptr += count;
		sclp_vt220_tty->flip.flag_buf_ptr += count;
		sclp_vt220_tty->flip.count += count;
		tty_flip_buffer_push(sclp_vt220_tty);
		break;
	}
}

/*
 * This routine is called when a particular tty device is opened.
 */
static int
sclp_vt220_open(struct tty_struct *tty, struct file *filp)
{
	if (tty->count == 1) {
		sclp_vt220_tty = tty;
		tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
		if (tty->driver_data == NULL)
			return -ENOMEM;
		tty->low_latency = 0;
	}
	return 0;
}

/*
 * This routine is called when a particular tty device is closed.
 */
static void
sclp_vt220_close(struct tty_struct *tty, struct file *filp)
{
	if (tty->count == 1) {
		sclp_vt220_tty = NULL;
		kfree(tty->driver_data);
		tty->driver_data = NULL;
	}
}

/*
 * This routine is called by the kernel to write a single
 * character to the tty device.  If the kernel uses this routine,
 * it must call the flush_chars() routine (if defined) when it is
 * done stuffing characters into the driver.
 *
 * NOTE: include/linux/tty_driver.h specifies that a character should be
 * ignored if there is no room in the queue. This driver implements a different
 * semantic in that it will block when there is no more room left.
 */
static void
sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
{
	__sclp_vt220_write(&ch, 1, 0, 0);
}

/*
 * This routine is called by the kernel after it has written a
 * series of characters to the tty device using put_char().  
 */
static void
sclp_vt220_flush_chars(struct tty_struct *tty)
{
	if (sclp_vt220_outqueue_count == 0)
		sclp_vt220_emit_current();
	else
		sclp_vt220_flush_later = 1;
}

/*
 * This routine returns the numbers of characters the tty driver
 * will accept for queuing to be written.  This number is subject
 * to change as output buffers get emptied, or if the output flow
 * control is acted.
 */
static int
sclp_vt220_write_room(struct tty_struct *tty)
{
	unsigned long flags;
	struct list_head *l;
	int count;

	spin_lock_irqsave(&sclp_vt220_lock, flags);
	count = 0;
	if (sclp_vt220_current_request != NULL)
		count = sclp_vt220_space_left(sclp_vt220_current_request);
	list_for_each(l, &sclp_vt220_empty)
		count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
	return count;
}

/*
 * Return number of buffered chars.
 */
static int
sclp_vt220_chars_in_buffer(struct tty_struct *tty)
{
	unsigned long flags;
	struct list_head *l;
	struct sclp_vt220_request *r;
	int count;

	spin_lock_irqsave(&sclp_vt220_lock, flags);
	count = 0;
	if (sclp_vt220_current_request != NULL)
		count = sclp_vt220_chars_stored(sclp_vt220_current_request);
	list_for_each(l, &sclp_vt220_outqueue) {
		r = list_entry(l, struct sclp_vt220_request, list);
		count += sclp_vt220_chars_stored(r);
	}
	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
	return count;
}

static void
__sclp_vt220_flush_buffer(void)
{
	unsigned long flags;

	sclp_vt220_emit_current();
	spin_lock_irqsave(&sclp_vt220_lock, flags);
	if (timer_pending(&sclp_vt220_timer))
		del_timer(&sclp_vt220_timer);
	while (sclp_vt220_outqueue_count > 0) {
		spin_unlock_irqrestore(&sclp_vt220_lock, flags);
		sclp_sync_wait();
		spin_lock_irqsave(&sclp_vt220_lock, flags);
	}
	spin_unlock_irqrestore(&sclp_vt220_lock, flags);
}

/*
 * Pass on all buffers to the hardware. Return only when there are no more
 * buffers pending.
 */
static void
sclp_vt220_flush_buffer(struct tty_struct *tty)
{
	sclp_vt220_emit_current();
}

/*
 * Initialize all relevant components and register driver with system.
 */
static int
__sclp_vt220_init(int early)
{
	void *page;
	int i;

	if (sclp_vt220_initialized)
		return 0;
	sclp_vt220_initialized = 1;
	spin_lock_init(&sclp_vt220_lock);
	INIT_LIST_HEAD(&sclp_vt220_empty);
	INIT_LIST_HEAD(&sclp_vt220_outqueue);
	init_waitqueue_head(&sclp_vt220_waitq);
	init_timer(&sclp_vt220_timer);
	sclp_vt220_current_request = NULL;
	sclp_vt220_buffered_chars = 0;
	sclp_vt220_outqueue_count = 0;
	sclp_vt220_tty = NULL;
	sclp_vt220_flush_later = 0;

	/* Allocate pages for output buffering */
	for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
		if (early)
			page = alloc_bootmem_low_pages(PAGE_SIZE);
		else
			page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
		if (!page)
			return -ENOMEM;
		list_add_tail((struct list_head *) page, &sclp_vt220_empty);
	}
	return 0;
}

static struct tty_operations sclp_vt220_ops = {
	.open = sclp_vt220_open,
	.close = sclp_vt220_close,
	.write = sclp_vt220_write,
	.put_char = sclp_vt220_put_char,
	.flush_chars = sclp_vt220_flush_chars,
	.write_room = sclp_vt220_write_room,
	.chars_in_buffer = sclp_vt220_chars_in_buffer,
	.flush_buffer = sclp_vt220_flush_buffer
};

/*
 * Register driver with SCLP and Linux and initialize internal tty structures.
 */
int __init
sclp_vt220_tty_init(void)
{
	struct tty_driver *driver;
	int rc;

	/* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
	 * symmetry between VM and LPAR systems regarding ttyS1. */
	driver = alloc_tty_driver(1);
	if (!driver)
		return -ENOMEM;
	rc = __sclp_vt220_init(0);
	if (rc) {
		put_tty_driver(driver);
		return rc;
	}
	rc = sclp_register(&sclp_vt220_register);
	if (rc) {
		printk(KERN_ERR SCLP_VT220_PRINT_HEADER
		       "could not register tty - "
		       "sclp_register returned %d\n", rc);
		put_tty_driver(driver);
		return rc;
	}

	driver->owner = THIS_MODULE;
	driver->driver_name = SCLP_VT220_DRIVER_NAME;
	driver->name = SCLP_VT220_DEVICE_NAME;
	driver->major = SCLP_VT220_MAJOR;
	driver->minor_start = SCLP_VT220_MINOR;
	driver->type = TTY_DRIVER_TYPE_SYSTEM;
	driver->subtype = SYSTEM_TYPE_TTY;
	driver->init_termios = tty_std_termios;
	driver->flags = TTY_DRIVER_REAL_RAW;
	tty_set_operations(driver, &sclp_vt220_ops);

	rc = tty_register_driver(driver);
	if (rc) {
		printk(KERN_ERR SCLP_VT220_PRINT_HEADER
		       "could not register tty - "
		       "tty_register_driver returned %d\n", rc);
		put_tty_driver(driver);
		return rc;
	}
	sclp_vt220_driver = driver;
	return 0;
}

module_init(sclp_vt220_tty_init);

#ifdef CONFIG_SCLP_VT220_CONSOLE

static void
sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
{
	__sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
}

static struct tty_driver *
sclp_vt220_con_device(struct console *c, int *index)
{
	*index = 0;
	return sclp_vt220_driver;
}

/*
 * This routine is called from panic when the kernel is going to give up.
 * We have to make sure that all buffers will be flushed to the SCLP.
 * Note that this function may be called from within an interrupt context.
 */
static void
sclp_vt220_con_unblank(void)
{
	__sclp_vt220_flush_buffer();
}

/* Structure needed to register with printk */
static struct console sclp_vt220_console =
{
	.name = SCLP_VT220_CONSOLE_NAME,
	.write = sclp_vt220_con_write,
	.device = sclp_vt220_con_device,
	.unblank = sclp_vt220_con_unblank,
	.flags = CON_PRINTBUFFER,
	.index = SCLP_VT220_CONSOLE_INDEX
};

static int __init
sclp_vt220_con_init(void)
{
	int rc;

	if (!CONSOLE_IS_SCLP)
		return 0;
	rc = __sclp_vt220_init(1);
	if (rc)
		return rc;
	/* Attach linux console */
	register_console(&sclp_vt220_console);
	return 0;
}

console_initcall(sclp_vt220_con_init);
#endif /* CONFIG_SCLP_VT220_CONSOLE */