Merge branch 'sparc64-vcc'

Jag Raman says:

====================
sparc64: Enable Virtual Console Concentrator (VCC)

Patchset to enable Virtual Console Concentrator (VCC). VCC provides
access to the serial console of a guest domain. It creates a RAW
VIO/LDC link between the guest domain & primary through which serial
console data is shared.

This set addresses feedback provided by Dave Miller. Cleanup of
driver state is also addressed in this set. Patches updated
are 4, 5, 6 & 7.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -12294,6 +12294,7 @@ F:	drivers/tty/serial/sunsab.h
 F:	drivers/tty/serial/sunsu.c
 F:	drivers/tty/serial/sunzilog.c
 F:	drivers/tty/serial/sunzilog.h
+F:	drivers/tty/vcc.c
 
 SPARSE CHECKER
 M:	"Christopher Li" <sparse@chrisli.org>

arch/sparc/configs/sparc64_defconfig

@@ -238,3 +238,4 @@ CONFIG_CRYPTO_TWOFISH=m
 # CONFIG_CRYPTO_ANSI_CPRNG is not set
 CONFIG_CRC16=m
 CONFIG_LIBCRC32C=m
+CONFIG_VCC=m

arch/sparc/include/asm/vio.h

@@ -52,6 +52,7 @@ struct vio_ver_info {
 #define VDEV_NETWORK_SWITCH	0x02
 #define VDEV_DISK		0x03
 #define VDEV_DISK_SERVER	0x04
+#define VDEV_CONSOLE_CON	0x05
 
 	u8			resv1[3];
 	u64			resv2[5];
@@ -282,6 +283,14 @@ struct vio_dring_state {
 	struct ldc_trans_cookie	cookies[VIO_MAX_RING_COOKIES];
 };
 
+#define VIO_TAG_SIZE		((int)sizeof(struct vio_msg_tag))
+#define VIO_VCC_MTU_SIZE	(LDC_PACKET_SIZE - VIO_TAG_SIZE)
+
+struct vio_vcc {
+	struct vio_msg_tag	tag;
+	char			data[VIO_VCC_MTU_SIZE];
+};
+
 static inline void *vio_dring_cur(struct vio_dring_state *dr)
 {
 	return dr->base + (dr->entry_size * dr->prod);

arch/sparc/kernel/ldc.c

@@ -1480,6 +1480,7 @@ int ldc_rx_reset(struct ldc_channel *lp)
 {
 	return __set_rx_head(lp, lp->rx_tail);
 }
+EXPORT_SYMBOL(ldc_rx_reset);
 
 void __ldc_print(struct ldc_channel *lp, const char *caller)
 {
@@ -1493,6 +1494,7 @@ void __ldc_print(struct ldc_channel *lp, const char *caller)
 		lp->tx_head, lp->tx_tail, lp->tx_num_entries,
 		lp->rcv_nxt, lp->snd_nxt);
 }
+EXPORT_SYMBOL(__ldc_print);
 
 static int write_raw(struct ldc_channel *lp, const void *buf, unsigned int size)
 {

arch/sparc/kernel/vio.c

@@ -246,6 +246,7 @@ u64 vio_vdev_node(struct mdesc_handle *hp, struct vio_dev *vdev)
 
 	return node;
 }
+EXPORT_SYMBOL(vio_vdev_node);
 
 static void vio_fill_channel_info(struct mdesc_handle *hp, u64 mp,
 				  struct vio_dev *vdev)

arch/sparc/kernel/viohs.c

@@ -814,15 +814,21 @@ int vio_driver_init(struct vio_driver_state *vio, struct vio_dev *vdev,
 	case VDEV_NETWORK_SWITCH:
 	case VDEV_DISK:
 	case VDEV_DISK_SERVER:
+	case VDEV_CONSOLE_CON:
 		break;
 
 	default:
 		return -EINVAL;
 	}
 
-	if (!ops || !ops->send_attr || !ops->handle_attr ||
-	    !ops->handshake_complete)
-		return -EINVAL;
+	if (dev_class == VDEV_NETWORK ||
+	    dev_class == VDEV_NETWORK_SWITCH ||
+	    dev_class == VDEV_DISK ||
+	    dev_class == VDEV_DISK_SERVER) {
+		if (!ops || !ops->send_attr || !ops->handle_attr ||
+		    !ops->handshake_complete)
+			return -EINVAL;
+	}
 
 	if (!ver_table || ver_table_size < 0)
 		return -EINVAL;

drivers/tty/Kconfig

@@ -455,4 +455,9 @@ config MIPS_EJTAG_FDC_KGDB_CHAN
 	help
 	  FDC channel number to use for KGDB.
 
+config VCC
+	tristate "Sun Virtual Console Concentrator"
+	depends on SUN_LDOMS
+	help
+	  Support for Sun logical domain consoles.
 endif # TTY

drivers/tty/Makefile

@@ -33,5 +33,6 @@ obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o
 obj-$(CONFIG_GOLDFISH_TTY)	+= goldfish.o
 obj-$(CONFIG_DA_TTY)		+= metag_da.o
 obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o
+obj-$(CONFIG_VCC)		+= vcc.o
 
 obj-y += ipwireless/

drivers/tty/vcc.c

@@ -0,0 +1,1155 @@
+/* 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 <asm/vio.h>
+#include <asm/ldc.h>
+
+#define DRV_MODULE_NAME		"vcc"
+#define DRV_MODULE_VERSION	"1.1"
+#define DRV_MODULE_RELDATE	"July 1, 2017"
+
+static char version[] =
+	DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")";
+
+MODULE_DESCRIPTION("Sun LDOM virtual console concentrator driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_MODULE_VERSION);
+
+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 const char vcc_driver_name[] = "vcc";
+static const char vcc_device_node[] = "vcc";
+static struct tty_driver *vcc_tty_driver;
+
+static struct vcc_port *vcc_table[VCC_MAX_PORTS];
+static DEFINE_SPINLOCK(vcc_table_lock);
+
+int vcc_dbg;
+int vcc_dbg_ldc;
+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 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(unsigned long index)
+{
+	struct vio_driver_state *vio;
+	struct vcc_port *port;
+	unsigned long flags;
+	int rv;
+
+	port = vcc_get_ne(index);
+	if (!port)
+		return;
+
+	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(unsigned long index)
+{
+	struct vcc_port *port;
+	struct vio_vcc *pkt;
+	unsigned long flags;
+	int tosend = 0;
+	int rv;
+
+	port = vcc_get_ne(index);
+	if (!port)
+		return;
+
+	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 vcc_sysfs_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 vcc_sysfs_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(domain, 0400, vcc_sysfs_domain_show, NULL);
+static DEVICE_ATTR(break, 0200, NULL, vcc_sysfs_break_store);
+
+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);
+
+	rv = vio_driver_init(&port->vio, vdev, VDEV_CONSOLE_CON, vcc_versions,
+			     ARRAY_SIZE(vcc_versions), NULL, name);
+	if (rv)
+		goto free_port;
+
+	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_port;
+
+	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");
+		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);
+
+	mdesc_release(hp);
+
+	rv = sysfs_create_group(&vdev->dev.kobj, &vcc_attribute_group);
+	if (rv)
+		goto free_domain;
+
+	init_timer(&port->rx_timer);
+	port->rx_timer.function = vcc_rx_timer;
+	port->rx_timer.data = port->index;
+
+	init_timer(&port->tx_timer);
+	port->tx_timer.function = vcc_tx_timer;
+	port->tx_timer.data = port->index;
+
+	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_port:
+	kfree(name);
+	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 int vcc_remove(struct vio_dev *vdev)
+{
+	struct vcc_port *port = dev_get_drvdata(&vdev->dev);
+
+	if (!port)
+		return -ENODEV;
+
+	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
+	 */
+	port = vcc_get(port->index, true);
+
+	if (WARN_ON(!port))
+		return -ENODEV;
+
+	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);
+	}
+
+	return 0;
+}
+
+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 (unlikely(!tty)) {
+		pr_err("VCC: open: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	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)) {
+		pr_err("VCC: close: Invalid TTY handle\n");
+		return;
+	}
+
+	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;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: hangup: Invalid TTY handle\n");
+		return;
+	}
+
+	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;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: write: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	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 int vcc_write_room(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+	u64 num;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: write_room: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: write_room: Failed to find VCC port\n");
+		return -ENODEV;
+	}
+
+	num = VCC_BUFF_LEN - port->chars_in_buffer;
+
+	vcc_put(port, false);
+
+	return num;
+}
+
+static int vcc_chars_in_buffer(struct tty_struct *tty)
+{
+	struct vcc_port *port;
+	u64 num;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: chars_in_buffer: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	port = vcc_get_ne(tty->index);
+	if (unlikely(!port)) {
+		pr_err("VCC: chars_in_buffer: Failed to find VCC port\n");
+		return -ENODEV;
+	}
+
+	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;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: break_ctl: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	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 (unlikely(!tty)) {
+		pr_err("VCC: install: Invalid TTY handle\n");
+		return -ENXIO;
+	}
+
+	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;
+
+	if (unlikely(!tty)) {
+		pr_err("VCC: cleanup: Invalid TTY handle\n");
+		return;
+	}
+
+	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;
+
+	pr_info("VCC: %s\n", version);
+
+	vcc_tty_driver = tty_alloc_driver(VCC_MAX_PORTS, VCC_TTY_FLAGS);
+	if (!vcc_tty_driver) {
+		pr_err("VCC: TTY driver alloc failed\n");
+		return -ENOMEM;
+	}
+
+	vcc_tty_driver->driver_name = vcc_driver_name;
+	vcc_tty_driver->name = vcc_device_node;
+
+	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");
+		put_tty_driver(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);
+	put_tty_driver(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);