Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1091 insertions, 0 deletions

diff --git a/drivers/tty/vcc.c b/drivers/tty/vcc.c
new file mode 100644
index 000000000..b8b832c75
--- /dev/null
+++ b/drivers/tty/vcc.c
@@ -0,0 +1,1091 @@
+// SPDX-License-Identifier: GPL-2.0
+/* vcc.c: sun4v virtual channel concentrator
+ *
+ * Copyright (C) 2017 Oracle. All rights reserved.
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/termios_internal.h>
+#include <asm/vio.h>
+#include <asm/ldc.h>
+
+MODULE_DESCRIPTION("Sun LDOM virtual console concentrator driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.1");
+
+struct vcc_port {
+	struct vio_driver_state vio;
+
+	spinlock_t lock;
+	char *domain;
+	struct tty_struct *tty;	/* only populated while dev is open */
+	unsigned long index;	/* index into the vcc_table */
+
+	u64 refcnt;
+	bool excl_locked;
+
+	bool removed;
+
+	/* This buffer is required to support the tty write_room interface
+	 * and guarantee that any characters that the driver accepts will
+	 * be eventually sent, either immediately or later.
+	 */
+	int chars_in_buffer;
+	struct vio_vcc buffer;
+
+	struct timer_list rx_timer;
+	struct timer_list tx_timer;
+};
+
+/* Microseconds that thread will delay waiting for a vcc port ref */
+#define VCC_REF_DELAY		100
+
+#define VCC_MAX_PORTS		1024
+#define VCC_MINOR_START		0	/* must be zero */
+#define VCC_BUFF_LEN		VIO_VCC_MTU_SIZE
+
+#define VCC_CTL_BREAK		-1
+#define VCC_CTL_HUP		-2
+
+static struct tty_driver *vcc_tty_driver;
+
+static struct vcc_port *vcc_table[VCC_MAX_PORTS];
+static DEFINE_SPINLOCK(vcc_table_lock);
+
+static unsigned int vcc_dbg;
+static unsigned int vcc_dbg_ldc;
+static unsigned int vcc_dbg_vio;
+
+module_param(vcc_dbg, uint, 0664);
+module_param(vcc_dbg_ldc, uint, 0664);
+module_param(vcc_dbg_vio, uint, 0664);
+
+#define VCC_DBG_DRV	0x1
+#define VCC_DBG_LDC	0x2
+#define VCC_DBG_PKT	0x4
+
+#define vccdbg(f, a...)						\
+	do {							\
+		if (vcc_dbg & VCC_DBG_DRV)			\
+			pr_info(f, ## a);			\
+	} while (0)						\
+
+#define vccdbgl(l)						\
+	do {							\
+		if (vcc_dbg & VCC_DBG_LDC)			\
+			ldc_print(l);				\
+	} while (0)						\
+
+#define vccdbgp(pkt)						\
+	do {							\
+		if (vcc_dbg & VCC_DBG_PKT) {			\
+			int i;					\
+			for (i = 0; i < pkt.tag.stype; i++)	\
+				pr_info("[%c]", pkt.data[i]);	\
+		}						\
+	} while (0)						\
+
+/* Note: Be careful when adding flags to this line discipline.  Don't
+ * add anything that will cause echoing or we'll go into recursive
+ * loop echoing chars back and forth with the console drivers.
+ */
+static const struct ktermios vcc_tty_termios = {
+	.c_iflag = IGNBRK | IGNPAR,
+	.c_oflag = OPOST,
+	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
+	.c_cc = INIT_C_CC,
+	.c_ispeed = 38400,
+	.c_ospeed = 38400
+};
+
+/**
+ * vcc_table_add() - Add VCC port to the VCC table
+ * @port: pointer to the VCC port
+ *
+ * Return: index of the port in the VCC table on success,
+ *	   -1 on failure
+ */
+static int vcc_table_add(struct vcc_port *port)
+{
+	unsigned long flags;
+	int i;
+
+	spin_lock_irqsave(&vcc_table_lock, flags);
+	for (i = VCC_MINOR_START; i < VCC_MAX_PORTS; i++) {
+		if (!vcc_table[i]) {
+			vcc_table[i] = port;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&vcc_table_lock, flags);
+
+	if (i < VCC_MAX_PORTS)
+		return i;
+	else
+		return -1;
+}
+
+/**
+ * vcc_table_remove() - Removes a VCC port from the VCC table
+ * @index: Index into the VCC table
+ */
+static void vcc_table_remove(unsigned long index)
+{
+	unsigned long flags;
+
+	if (WARN_ON(index >= VCC_MAX_PORTS))
+		return;
+
+	spin_lock_irqsave(&vcc_table_lock, flags);
+	vcc_table[index] = NULL;
+	spin_unlock_irqrestore(&vcc_table_lock, flags);
+}
+
+/**
+ * vcc_get() - Gets a reference to VCC port
+ * @index: Index into the VCC table
+ * @excl: Indicates if an exclusive access is requested
+ *
+ * Return: reference to the VCC port, if found
+ *	   NULL, if port not found
+ */
+static struct vcc_port *vcc_get(unsigned long index, bool excl)
+{
+	struct vcc_port *port;
+	unsigned long flags;
+
+try_again:
+	spin_lock_irqsave(&vcc_table_lock, flags);
+
+	port = vcc_table[index];
+	if (!port) {
+		spin_unlock_irqrestore(&vcc_table_lock, flags);
+		return NULL;
+	}
+
+	if (!excl) {
+		if (port->excl_locked) {
+			spin_unlock_irqrestore(&vcc_table_lock, flags);
+			udelay(VCC_REF_DELAY);
+			goto try_again;
+		}
+		port->refcnt++;
+		spin_unlock_irqrestore(&vcc_table_lock, flags);
+		return port;
+	}
+
+	if (port->refcnt) {
+		spin_unlock_irqrestore(&vcc_table_lock, flags);
+		/* Threads wanting exclusive access will wait half the time,
+		 * probably giving them higher priority in the case of
+		 * multiple waiters.
+		 */
+		udelay(VCC_REF_DELAY/2);
+		goto try_again;
+	}
+
+	port->refcnt++;
+	port->excl_locked = true;
+	spin_unlock_irqrestore(&vcc_table_lock, flags);
+
+	return port;
+}
+
+/**
+ * vcc_put() - Returns a reference to VCC port
+ * @port: pointer to VCC port
+ * @excl: Indicates if the returned reference is an exclusive reference
+ *
+ * Note: It's the caller's responsibility to ensure the correct value
+ *	 for the excl flag
+ */
+static void vcc_put(struct vcc_port *port, bool excl)
+{
+	unsigned long flags;
+
+	if (!port)
+		return;
+
+	spin_lock_irqsave(&vcc_table_lock, flags);
+
+	/* check if caller attempted to put with the wrong flags */
+	if (WARN_ON((excl && !port->excl_locked) ||
+		    (!excl && port->excl_locked)))
+		goto done;
+
+	port->refcnt--;
+
+	if (excl)
+		port->excl_locked = false;
+
+done:
+	spin_unlock_irqrestore(&vcc_table_lock, flags);
+}
+
+/**
+ * vcc_get_ne() - Get a non-exclusive reference to VCC port
+ * @index: Index into the VCC table
+ *
+ * Gets a non-exclusive reference to VCC port, if it's not removed
+ *
+ * Return: pointer to the VCC port, if found
+ *	   NULL, if port not found
+ */
+static struct vcc_port *vcc_get_ne(unsigned long index)
+{
+	struct vcc_port *port;
+
+	port = vcc_get(index, false);
+
+	if (port && port->removed) {
+		vcc_put(port, false);
+		return NULL;
+	}
+
+	return port;
+}
+
+static void vcc_kick_rx(struct vcc_port *port)
+{
+	struct vio_driver_state *vio = &port->vio;
+
+	assert_spin_locked(&port->lock);
+
+	if (!timer_pending(&port->rx_timer) && !port->removed) {
+		disable_irq_nosync(vio->vdev->rx_irq);
+		port->rx_timer.expires = (jiffies + 1);
+		add_timer(&port->rx_timer);
+	}
+}
+
+static void vcc_kick_tx(struct vcc_port *port)
+{
+	assert_spin_locked(&port->lock);
+
+	if (!timer_pending(&port->tx_timer) && !port->removed) {
+		port->tx_timer.expires = (jiffies + 1);
+		add_timer(&port->tx_timer);
+	}
+}
+
+static int vcc_rx_check(struct tty_struct *tty, int size)
+{
+	if (WARN_ON(!tty || !tty->port))
+		return 1;
+
+	/* tty_buffer_request_room won't sleep because it uses
+	 * GFP_ATOMIC flag to allocate buffer
+	 */
+	if (test_bit(TTY_THROTTLED, &tty->flags) ||
+	    (tty_buffer_request_room(tty->port, VCC_BUFF_LEN) < VCC_BUFF_LEN))
+		return 0;
+
+	return 1;
+}
+
+static int vcc_rx(struct tty_struct *tty, char *buf, int size)
+{
+	int len = 0;
+
+	if (WARN_ON(!tty || !tty->port))
+		return len;
+
+	len = tty_insert_flip_string(tty->port, buf, size);
+	if (len)
+		tty_flip_buffer_push(tty->port);
+
+	return len;
+}
+
+static int vcc_ldc_read(struct vcc_port *port)
+{
+	struct vio_driver_state *vio = &port->vio;
+	struct tty_struct *tty;
+	struct vio_vcc pkt;
+	int rv = 0;
+
+	tty = port->tty;
+	if (!tty) {
+		rv = ldc_rx_reset(vio->lp);
+		vccdbg("VCC: reset rx q: rv=%d\n", rv);
+		goto done;
+	}
+
+	/* Read as long as LDC has incoming data. */
+	while (1) {
+		if (!vcc_rx_check(tty, VIO_VCC_MTU_SIZE)) {
+			vcc_kick_rx(port);
+			break;
+		}
+
+		vccdbgl(vio->lp);
+
+		rv = ldc_read(vio->lp, &pkt, sizeof(pkt));
+		if (rv <= 0)
+			break;
+
+		vccdbg("VCC: ldc_read()=%d\n", rv);
+		vccdbg("TAG [%02x:%02x:%04x:%08x]\n",
+		       pkt.tag.type, pkt.tag.stype,
+		       pkt.tag.stype_env, pkt.tag.sid);
+
+		if (pkt.tag.type == VIO_TYPE_DATA) {
+			vccdbgp(pkt);
+			/* vcc_rx_check ensures memory availability */
+			vcc_rx(tty, pkt.data, pkt.tag.stype);
+		} else {
+			pr_err("VCC: unknown msg [%02x:%02x:%04x:%08x]\n",
+			       pkt.tag.type, pkt.tag.stype,
+			       pkt.tag.stype_env, pkt.tag.sid);
+			rv = -ECONNRESET;
+			break;
+		}
+
+		WARN_ON(rv != LDC_PACKET_SIZE);
+	}
+
+done:
+	return rv;
+}
+
+static void vcc_rx_timer(struct timer_list *t)
+{
+	struct vcc_port *port = from_timer(port, t, rx_timer);
+	struct vio_driver_state *vio;
+	unsigned long flags;
+	int rv;
+
+	spin_lock_irqsave(&port->lock, flags);
+	port->rx_timer.expires = 0;
+
+	vio = &port->vio;
+
+	enable_irq(vio->vdev->rx_irq);
+
+	if (!port->tty || port->removed)
+		goto done;
+
+	rv = vcc_ldc_read(port);
+	if (rv == -ECONNRESET)
+		vio_conn_reset(vio);
+
+done:
+	spin_unlock_irqrestore(&port->lock, flags);
+	vcc_put(port, false);
+}
+
+static void vcc_tx_timer(struct timer_list *t)
+{
+	struct vcc_port *port = from_timer(port, t, tx_timer);
+	struct vio_vcc *pkt;
+	unsigned long flags;
+	int tosend = 0;
+	int rv;
+
+	spin_lock_irqsave(&port->lock, flags);
+	port->tx_timer.expires = 0;
+
+	if (!port->tty || port->removed)
+		goto done;
+
+	tosend = min(VCC_BUFF_LEN, port->chars_in_buffer);
+	if (!tosend)
+		goto done;
+
+	pkt = &port->buffer;
+	pkt->tag.type = VIO_TYPE_DATA;
+	pkt->tag.stype = tosend;
+	vccdbgl(port->vio.lp);
+
+	rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
+	WARN_ON(!rv);
+
+	if (rv < 0) {
+		vccdbg("VCC: ldc_write()=%d\n", rv);
+		vcc_kick_tx(port);
+	} else {
+		struct tty_struct *tty = port->tty;
+
+		port->chars_in_buffer = 0;
+		if (tty)
+			tty_wakeup(tty);
+	}
+
+done:
+	spin_unlock_irqrestore(&port->lock, flags);
+	vcc_put(port, false);
+}
+
+/**
+ * vcc_event() - LDC event processing engine
+ * @arg: VCC private data
+ * @event: LDC event
+ *
+ * Handles LDC events for VCC
+ */
+static void vcc_event(void *arg, int event)
+{
+	struct vio_driver_state *vio;
+	struct vcc_port *port;
+	unsigned long flags;
+	int rv;
+
+	port = arg;
+	vio = &port->vio;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	switch (event) {
+	case LDC_EVENT_RESET:
+	case LDC_EVENT_UP:
+		vio_link_state_change(vio, event);
+		break;
+
+	case LDC_EVENT_DATA_READY:
+		rv = vcc_ldc_read(port);
+		if (rv == -ECONNRESET)
+			vio_conn_reset(vio);
+		break;
+
+	default:
+		pr_err("VCC: unexpected LDC event(%d)\n", event);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static struct ldc_channel_config vcc_ldc_cfg = {
+	.event		= vcc_event,
+	.mtu		= VIO_VCC_MTU_SIZE,
+	.mode		= LDC_MODE_RAW,
+	.debug		= 0,
+};
+
+/* Ordered from largest major to lowest */
+static struct vio_version vcc_versions[] = {
+	{ .major = 1, .minor = 0 },
+};
+
+static struct tty_port_operations vcc_port_ops = { 0 };
+
+static ssize_t domain_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	struct vcc_port *port;
+	int rv;
+
+	port = dev_get_drvdata(dev);
+	if (!port)
+		return -ENODEV;
+
+	rv = scnprintf(buf, PAGE_SIZE, "%s\n", port->domain);
+
+	return rv;
+}
+
+static int vcc_send_ctl(struct vcc_port *port, int ctl)
+{
+	struct vio_vcc pkt;
+	int rv;
+
+	pkt.tag.type = VIO_TYPE_CTRL;
+	pkt.tag.sid = ctl;
+	pkt.tag.stype = 0;
+
+	rv = ldc_write(port->vio.lp, &pkt, sizeof(pkt.tag));
+	WARN_ON(!rv);
+	vccdbg("VCC: ldc_write(%ld)=%d\n", sizeof(pkt.tag), rv);
+
+	return rv;
+}
+
+static ssize_t break_store(struct device *dev,
+			   struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct vcc_port *port;
+	unsigned long flags;
+	int rv = count;
+	int brk;
+
+	port = dev_get_drvdata(dev);
+	if (!port)
+		return -ENODEV;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (sscanf(buf, "%ud", &brk) != 1 || brk != 1)
+		rv = -EINVAL;
+	else if (vcc_send_ctl(port, VCC_CTL_BREAK) < 0)
+		vcc_kick_tx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return rv;
+}
+
+static DEVICE_ATTR_ADMIN_RO(domain);
+static DEVICE_ATTR_WO(break);
+
+static struct attribute *vcc_sysfs_entries[] = {
+	&dev_attr_domain.attr,
+	&dev_attr_break.attr,
+	NULL
+};
+
+static struct attribute_group vcc_attribute_group = {
+	.name = NULL,
+	.attrs = vcc_sysfs_entries,
+};
+
+/**
+ * vcc_probe() - Initialize VCC port
+ * @vdev: Pointer to VIO device of the new VCC port
+ * @id: VIO device ID
+ *
+ * Initializes a VCC port to receive serial console data from
+ * the guest domain. Sets up a TTY end point on the control
+ * domain. Sets up VIO/LDC link between the guest & control
+ * domain endpoints.
+ *
+ * Return: status of the probe
+ */
+static int vcc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
+{
+	struct mdesc_handle *hp;
+	struct vcc_port *port;
+	struct device *dev;
+	const char *domain;
+	char *name;
+	u64 node;
+	int rv;
+
+	vccdbg("VCC: name=%s\n", dev_name(&vdev->dev));
+
+	if (!vcc_tty_driver) {
+		pr_err("VCC: TTY driver not registered\n");
+		return -ENODEV;
+	}
+
+	port = kzalloc(sizeof(struct vcc_port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	name = kstrdup(dev_name(&vdev->dev), GFP_KERNEL);
+	if (!name) {
+		rv = -ENOMEM;
+		goto free_port;
+	}
+
+	rv = vio_driver_init(&port->vio, vdev, VDEV_CONSOLE_CON, vcc_versions,
+			     ARRAY_SIZE(vcc_versions), NULL, name);
+	if (rv)
+		goto free_name;
+
+	port->vio.debug = vcc_dbg_vio;
+	vcc_ldc_cfg.debug = vcc_dbg_ldc;
+
+	rv = vio_ldc_alloc(&port->vio, &vcc_ldc_cfg, port);
+	if (rv)
+		goto free_name;
+
+	spin_lock_init(&port->lock);
+
+	port->index = vcc_table_add(port);
+	if (port->index == -1) {
+		pr_err("VCC: no more TTY indices left for allocation\n");
+		rv = -ENOMEM;
+		goto free_ldc;
+	}
+
+	/* Register the device using VCC table index as TTY index */
+	dev = tty_register_device(vcc_tty_driver, port->index, &vdev->dev);
+	if (IS_ERR(dev)) {
+		rv = PTR_ERR(dev);
+		goto free_table;
+	}
+
+	hp = mdesc_grab();
+
+	node = vio_vdev_node(hp, vdev);
+	if (node == MDESC_NODE_NULL) {
+		rv = -ENXIO;
+		mdesc_release(hp);
+		goto unreg_tty;
+	}
+
+	domain = mdesc_get_property(hp, node, "vcc-domain-name", NULL);
+	if (!domain) {
+		rv = -ENXIO;
+		mdesc_release(hp);
+		goto unreg_tty;
+	}
+	port->domain = kstrdup(domain, GFP_KERNEL);
+	if (!port->domain) {
+		rv = -ENOMEM;
+		goto unreg_tty;
+	}
+
+
+	mdesc_release(hp);
+
+	rv = sysfs_create_group(&vdev->dev.kobj, &vcc_attribute_group);
+	if (rv)
+		goto free_domain;
+
+	timer_setup(&port->rx_timer, vcc_rx_timer, 0);
+	timer_setup(&port->tx_timer, vcc_tx_timer, 0);
+
+	dev_set_drvdata(&vdev->dev, port);
+
+	/* It's possible to receive IRQs in the middle of vio_port_up. Disable
+	 * IRQs until the port is up.
+	 */
+	disable_irq_nosync(vdev->rx_irq);
+	vio_port_up(&port->vio);
+	enable_irq(vdev->rx_irq);
+
+	return 0;
+
+free_domain:
+	kfree(port->domain);
+unreg_tty:
+	tty_unregister_device(vcc_tty_driver, port->index);
+free_table:
+	vcc_table_remove(port->index);
+free_ldc:
+	vio_ldc_free(&port->vio);
+free_name:
+	kfree(name);
+free_port:
+	kfree(port);
+
+	return rv;
+}
+
+/**
+ * vcc_remove() - Terminate a VCC port
+ * @vdev: Pointer to VIO device of the VCC port
+ *
+ * Terminates a VCC port. Sets up the teardown of TTY and
+ * VIO/LDC link between guest and primary domains.
+ *
+ * Return: status of removal
+ */
+static void vcc_remove(struct vio_dev *vdev)
+{
+	struct vcc_port *port = dev_get_drvdata(&vdev->dev);
+
+	del_timer_sync(&port->rx_timer);
+	del_timer_sync(&port->tx_timer);
+
+	/* If there's a process with the device open, do a synchronous
+	 * hangup of the TTY. This *may* cause the process to call close
+	 * asynchronously, but it's not guaranteed.
+	 */
+	if (port->tty)
+		tty_vhangup(port->tty);
+
+	/* Get exclusive reference to VCC, ensures that there are no other
+	 * clients to this port. This cannot fail.
+	 */
+	vcc_get(port->index, true);
+
+	tty_unregister_device(vcc_tty_driver, port->index);
+
+	del_timer_sync(&port->vio.timer);
+	vio_ldc_free(&port->vio);
+	sysfs_remove_group(&vdev->dev.kobj, &vcc_attribute_group);
+	dev_set_drvdata(&vdev->dev, NULL);
+	if (port->tty) {
+		port->removed = true;
+		vcc_put(port, true);
+	} else {
+		vcc_table_remove(port->index);
+
+		kfree(port->vio.name);
+		kfree(port->domain);
+		kfree(port);
+	}
+}
+
+static const struct vio_device_id vcc_match[] = {
+	{
+		.type = "vcc-port",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(vio, vcc_match);
+
+static struct vio_driver vcc_driver = {
+	.id_table	= vcc_match,
+	.probe		= vcc_probe,
+	.remove		= vcc_remove,
+	.name		= "vcc",
+};
+
+static int vcc_open(struct tty_struct *tty, struct file *vcc_file)
+{
+	struct vcc_port *port;
+
+	if (tty->count > 1)
+		return -EBUSY;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: open: Failed to find VCC port\n");
+		return -ENODEV;
+	}
+
+	if (unlikely(!port->vio.lp)) {
+		pr_err("VCC: open: LDC channel not configured\n");
+		vcc_put(port, false);
+		return -EPIPE;
+	}
+	vccdbgl(port->vio.lp);
+
+	vcc_put(port, false);
+
+	if (unlikely(!tty->port)) {
+		pr_err("VCC: open: TTY port not found\n");
+		return -ENXIO;
+	}
+
+	if (unlikely(!tty->port->ops)) {
+		pr_err("VCC: open: TTY ops not defined\n");
+		return -ENXIO;
+	}
+
+	return tty_port_open(tty->port, tty, vcc_file);
+}
+
+static void vcc_close(struct tty_struct *tty, struct file *vcc_file)
+{
+	if (unlikely(tty->count > 1))
+		return;
+
+	if (unlikely(!tty->port)) {
+		pr_err("VCC: close: TTY port not found\n");
+		return;
+	}
+
+	tty_port_close(tty->port, tty, vcc_file);
+}
+
+static void vcc_ldc_hup(struct vcc_port *port)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (vcc_send_ctl(port, VCC_CTL_HUP) < 0)
+		vcc_kick_tx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void vcc_hangup(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: hangup: Failed to find VCC port\n");
+		return;
+	}
+
+	if (unlikely(!tty->port)) {
+		pr_err("VCC: hangup: TTY port not found\n");
+		vcc_put(port, false);
+		return;
+	}
+
+	vcc_ldc_hup(port);
+
+	vcc_put(port, false);
+
+	tty_port_hangup(tty->port);
+}
+
+static int vcc_write(struct tty_struct *tty, const unsigned char *buf,
+		     int count)
+{
+	struct vcc_port *port;
+	struct vio_vcc *pkt;
+	unsigned long flags;
+	int total_sent = 0;
+	int tosend = 0;
+	int rv = -EINVAL;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: write: Failed to find VCC port");
+		return -ENODEV;
+	}
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	pkt = &port->buffer;
+	pkt->tag.type = VIO_TYPE_DATA;
+
+	while (count > 0) {
+		/* Minimum of data to write and space available */
+		tosend = min(count, (VCC_BUFF_LEN - port->chars_in_buffer));
+
+		if (!tosend)
+			break;
+
+		memcpy(&pkt->data[port->chars_in_buffer], &buf[total_sent],
+		       tosend);
+		port->chars_in_buffer += tosend;
+		pkt->tag.stype = tosend;
+
+		vccdbg("TAG [%02x:%02x:%04x:%08x]\n", pkt->tag.type,
+		       pkt->tag.stype, pkt->tag.stype_env, pkt->tag.sid);
+		vccdbg("DATA [%s]\n", pkt->data);
+		vccdbgl(port->vio.lp);
+
+		/* Since we know we have enough room in VCC buffer for tosend
+		 * we record that it was sent regardless of whether the
+		 * hypervisor actually took it because we have it buffered.
+		 */
+		rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
+		vccdbg("VCC: write: ldc_write(%d)=%d\n",
+		       (VIO_TAG_SIZE + tosend), rv);
+
+		total_sent += tosend;
+		count -= tosend;
+		if (rv < 0) {
+			vcc_kick_tx(port);
+			break;
+		}
+
+		port->chars_in_buffer = 0;
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	vcc_put(port, false);
+
+	vccdbg("VCC: write: total=%d rv=%d", total_sent, rv);
+
+	return total_sent ? total_sent : rv;
+}
+
+static unsigned int vcc_write_room(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+	unsigned int num;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: write_room: Failed to find VCC port\n");
+		return 0;
+	}
+
+	num = VCC_BUFF_LEN - port->chars_in_buffer;
+
+	vcc_put(port, false);
+
+	return num;
+}
+
+static unsigned int vcc_chars_in_buffer(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+	unsigned int num;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: chars_in_buffer: Failed to find VCC port\n");
+		return 0;
+	}
+
+	num = port->chars_in_buffer;
+
+	vcc_put(port, false);
+
+	return num;
+}
+
+static int vcc_break_ctl(struct tty_struct *tty, int state)
+{
+	struct vcc_port *port;
+	unsigned long flags;
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: break_ctl: Failed to find VCC port\n");
+		return -ENODEV;
+	}
+
+	/* Turn off break */
+	if (state == 0) {
+		vcc_put(port, false);
+		return 0;
+	}
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (vcc_send_ctl(port, VCC_CTL_BREAK) < 0)
+		vcc_kick_tx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	vcc_put(port, false);
+
+	return 0;
+}
+
+static int vcc_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct vcc_port *port_vcc;
+	struct tty_port *port_tty;
+	int ret;
+
+	if (tty->index >= VCC_MAX_PORTS)
+		return -EINVAL;
+
+	ret = tty_standard_install(driver, tty);
+	if (ret)
+		return ret;
+
+	port_tty = kzalloc(sizeof(struct tty_port), GFP_KERNEL);
+	if (!port_tty)
+		return -ENOMEM;
+
+	port_vcc = vcc_get(tty->index, true);
+	if (!port_vcc) {
+		pr_err("VCC: install: Failed to find VCC port\n");
+		tty->port = NULL;
+		kfree(port_tty);
+		return -ENODEV;
+	}
+
+	tty_port_init(port_tty);
+	port_tty->ops = &vcc_port_ops;
+	tty->port = port_tty;
+
+	port_vcc->tty = tty;
+
+	vcc_put(port_vcc, true);
+
+	return 0;
+}
+
+static void vcc_cleanup(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+
+	port = vcc_get(tty->index, true);
+	if (port) {
+		port->tty = NULL;
+
+		if (port->removed) {
+			vcc_table_remove(tty->index);
+			kfree(port->vio.name);
+			kfree(port->domain);
+			kfree(port);
+		} else {
+			vcc_put(port, true);
+		}
+	}
+
+	tty_port_destroy(tty->port);
+	kfree(tty->port);
+	tty->port = NULL;
+}
+
+static const struct tty_operations vcc_ops = {
+	.open			= vcc_open,
+	.close			= vcc_close,
+	.hangup			= vcc_hangup,
+	.write			= vcc_write,
+	.write_room		= vcc_write_room,
+	.chars_in_buffer	= vcc_chars_in_buffer,
+	.break_ctl		= vcc_break_ctl,
+	.install		= vcc_install,
+	.cleanup		= vcc_cleanup,
+};
+
+#define VCC_TTY_FLAGS   (TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_REAL_RAW)
+
+static int vcc_tty_init(void)
+{
+	int rv;
+
+	vcc_tty_driver = tty_alloc_driver(VCC_MAX_PORTS, VCC_TTY_FLAGS);
+	if (IS_ERR(vcc_tty_driver)) {
+		pr_err("VCC: TTY driver alloc failed\n");
+		return PTR_ERR(vcc_tty_driver);
+	}
+
+	vcc_tty_driver->driver_name = "vcc";
+	vcc_tty_driver->name = "vcc";
+
+	vcc_tty_driver->minor_start = VCC_MINOR_START;
+	vcc_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
+	vcc_tty_driver->init_termios = vcc_tty_termios;
+
+	tty_set_operations(vcc_tty_driver, &vcc_ops);
+
+	rv = tty_register_driver(vcc_tty_driver);
+	if (rv) {
+		pr_err("VCC: TTY driver registration failed\n");
+		tty_driver_kref_put(vcc_tty_driver);
+		vcc_tty_driver = NULL;
+		return rv;
+	}
+
+	vccdbg("VCC: TTY driver registered\n");
+
+	return 0;
+}
+
+static void vcc_tty_exit(void)
+{
+	tty_unregister_driver(vcc_tty_driver);
+	tty_driver_kref_put(vcc_tty_driver);
+	vccdbg("VCC: TTY driver unregistered\n");
+
+	vcc_tty_driver = NULL;
+}
+
+static int __init vcc_init(void)
+{
+	int rv;
+
+	rv = vcc_tty_init();
+	if (rv) {
+		pr_err("VCC: TTY init failed\n");
+		return rv;
+	}
+
+	rv = vio_register_driver(&vcc_driver);
+	if (rv) {
+		pr_err("VCC: VIO driver registration failed\n");
+		vcc_tty_exit();
+	} else {
+		vccdbg("VCC: VIO driver registered successfully\n");
+	}
+
+	return rv;
+}
+
+static void __exit vcc_exit(void)
+{
+	vio_unregister_driver(&vcc_driver);
+	vccdbg("VCC: VIO driver unregistered\n");
+	vcc_tty_exit();
+	vccdbg("VCC: TTY driver unregistered\n");
+}
+
+module_init(vcc_init);
+module_exit(vcc_exit);