powerpc: Move viopath.c to powerpc/platforms/iseries

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

1 files changed, 672 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/iseries/viopath.c b/arch/powerpc/platforms/iseries/viopath.c
new file mode 100644
index 00000000000..c0c767bd37f
--- /dev/null
+++ b/arch/powerpc/platforms/iseries/viopath.c
@@ -0,0 +1,672 @@
+/* -*- linux-c -*-
+ *
+ *  iSeries Virtual I/O Message Path code
+ *
+ *  Authors: Dave Boutcher <boutcher@us.ibm.com>
+ *           Ryan Arnold <ryanarn@us.ibm.com>
+ *           Colin Devilbiss <devilbis@us.ibm.com>
+ *
+ * (C) Copyright 2000-2005 IBM Corporation
+ *
+ * This code is used by the iSeries virtual disk, cd,
+ * tape, and console to communicate with OS/400 in another
+ * partition.
+ *
+ * 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) anyu 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/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/vmalloc.h>
+#include <linux/string.h>
+#include <linux/proc_fs.h>
+#include <linux/dma-mapping.h>
+#include <linux/wait.h>
+#include <linux/seq_file.h>
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/iSeries/HvTypes.h>
+#include <asm/iSeries/ItExtVpdPanel.h>
+#include <asm/iSeries/HvLpEvent.h>
+#include <asm/iSeries/HvLpConfig.h>
+#include <asm/iSeries/mf.h>
+#include <asm/iSeries/vio.h>
+
+/* Status of the path to each other partition in the system.
+ * This is overkill, since we will only ever establish connections
+ * to our hosting partition and the primary partition on the system.
+ * But this allows for other support in the future.
+ */
+static struct viopathStatus {
+	int isOpen;		/* Did we open the path?            */
+	int isActive;		/* Do we have a mon msg outstanding */
+	int users[VIO_MAX_SUBTYPES];
+	HvLpInstanceId mSourceInst;
+	HvLpInstanceId mTargetInst;
+	int numberAllocated;
+} viopathStatus[HVMAXARCHITECTEDLPS];
+
+static DEFINE_SPINLOCK(statuslock);
+
+/*
+ * For each kind of event we allocate a buffer that is
+ * guaranteed not to cross a page boundary
+ */
+static unsigned char event_buffer[VIO_MAX_SUBTYPES * 256] __page_aligned;
+static atomic_t event_buffer_available[VIO_MAX_SUBTYPES];
+static int event_buffer_initialised;
+
+static void handleMonitorEvent(struct HvLpEvent *event);
+
+/*
+ * We use this structure to handle asynchronous responses.  The caller
+ * blocks on the semaphore and the handler posts the semaphore.  However,
+ * if system_state is not SYSTEM_RUNNING, then wait_atomic is used ...
+ */
+struct alloc_parms {
+	struct semaphore sem;
+	int number;
+	atomic_t wait_atomic;
+	int used_wait_atomic;
+};
+
+/* Put a sequence number in each mon msg.  The value is not
+ * important.  Start at something other than 0 just for
+ * readability.  wrapping this is ok.
+ */
+static u8 viomonseq = 22;
+
+/* Our hosting logical partition.  We get this at startup
+ * time, and different modules access this variable directly.
+ */
+HvLpIndex viopath_hostLp = HvLpIndexInvalid;
+EXPORT_SYMBOL(viopath_hostLp);
+HvLpIndex viopath_ourLp = HvLpIndexInvalid;
+EXPORT_SYMBOL(viopath_ourLp);
+
+/* For each kind of incoming event we set a pointer to a
+ * routine to call.
+ */
+static vio_event_handler_t *vio_handler[VIO_MAX_SUBTYPES];
+
+#define VIOPATH_KERN_WARN	KERN_WARNING "viopath: "
+#define VIOPATH_KERN_INFO	KERN_INFO "viopath: "
+
+static int proc_viopath_show(struct seq_file *m, void *v)
+{
+	char *buf;
+	u16 vlanMap;
+	dma_addr_t handle;
+	HvLpEvent_Rc hvrc;
+	DECLARE_MUTEX_LOCKED(Semaphore);
+
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return 0;
+	memset(buf, 0, PAGE_SIZE);
+
+	handle = dma_map_single(iSeries_vio_dev, buf, PAGE_SIZE,
+				DMA_FROM_DEVICE);
+
+	hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_config | vioconfigget,
+			HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(viopath_hostLp),
+			viopath_targetinst(viopath_hostLp),
+			(u64)(unsigned long)&Semaphore, VIOVERSION << 16,
+			((u64)handle) << 32, PAGE_SIZE, 0, 0);
+
+	if (hvrc != HvLpEvent_Rc_Good)
+		printk(VIOPATH_KERN_WARN "hv error on op %d\n", (int)hvrc);
+
+	down(&Semaphore);
+
+	vlanMap = HvLpConfig_getVirtualLanIndexMap();
+
+	buf[PAGE_SIZE-1] = '\0';
+	seq_printf(m, "%s", buf);
+	seq_printf(m, "AVAILABLE_VETH=%x\n", vlanMap);
+	seq_printf(m, "SRLNBR=%c%c%c%c%c%c%c\n",
+		   e2a(xItExtVpdPanel.mfgID[2]),
+		   e2a(xItExtVpdPanel.mfgID[3]),
+		   e2a(xItExtVpdPanel.systemSerial[1]),
+		   e2a(xItExtVpdPanel.systemSerial[2]),
+		   e2a(xItExtVpdPanel.systemSerial[3]),
+		   e2a(xItExtVpdPanel.systemSerial[4]),
+		   e2a(xItExtVpdPanel.systemSerial[5]));
+
+	dma_unmap_single(iSeries_vio_dev, handle, PAGE_SIZE, DMA_FROM_DEVICE);
+	kfree(buf);
+
+	return 0;
+}
+
+static int proc_viopath_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_viopath_show, NULL);
+}
+
+static struct file_operations proc_viopath_operations = {
+	.open		= proc_viopath_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init vio_proc_init(void)
+{
+	struct proc_dir_entry *e;
+
+	e = create_proc_entry("iSeries/config", 0, NULL);
+	if (e)
+		e->proc_fops = &proc_viopath_operations;
+
+        return 0;
+}
+__initcall(vio_proc_init);
+
+/* See if a given LP is active.  Allow for invalid lps to be passed in
+ * and just return invalid
+ */
+int viopath_isactive(HvLpIndex lp)
+{
+	if (lp == HvLpIndexInvalid)
+		return 0;
+	if (lp < HVMAXARCHITECTEDLPS)
+		return viopathStatus[lp].isActive;
+	else
+		return 0;
+}
+EXPORT_SYMBOL(viopath_isactive);
+
+/*
+ * We cache the source and target instance ids for each
+ * partition.
+ */
+HvLpInstanceId viopath_sourceinst(HvLpIndex lp)
+{
+	return viopathStatus[lp].mSourceInst;
+}
+EXPORT_SYMBOL(viopath_sourceinst);
+
+HvLpInstanceId viopath_targetinst(HvLpIndex lp)
+{
+	return viopathStatus[lp].mTargetInst;
+}
+EXPORT_SYMBOL(viopath_targetinst);
+
+/*
+ * Send a monitor message.  This is a message with the acknowledge
+ * bit on that the other side will NOT explicitly acknowledge.  When
+ * the other side goes down, the hypervisor will acknowledge any
+ * outstanding messages....so we will know when the other side dies.
+ */
+static void sendMonMsg(HvLpIndex remoteLp)
+{
+	HvLpEvent_Rc hvrc;
+
+	viopathStatus[remoteLp].mSourceInst =
+		HvCallEvent_getSourceLpInstanceId(remoteLp,
+				HvLpEvent_Type_VirtualIo);
+	viopathStatus[remoteLp].mTargetInst =
+		HvCallEvent_getTargetLpInstanceId(remoteLp,
+				HvLpEvent_Type_VirtualIo);
+
+	/*
+	 * Deliberately ignore the return code here.  if we call this
+	 * more than once, we don't care.
+	 */
+	vio_setHandler(viomajorsubtype_monitor, handleMonitorEvent);
+
+	hvrc = HvCallEvent_signalLpEventFast(remoteLp, HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_monitor, HvLpEvent_AckInd_DoAck,
+			HvLpEvent_AckType_DeferredAck,
+			viopathStatus[remoteLp].mSourceInst,
+			viopathStatus[remoteLp].mTargetInst,
+			viomonseq++, 0, 0, 0, 0, 0);
+
+	if (hvrc == HvLpEvent_Rc_Good)
+		viopathStatus[remoteLp].isActive = 1;
+	else {
+		printk(VIOPATH_KERN_WARN "could not connect to partition %d\n",
+				remoteLp);
+		viopathStatus[remoteLp].isActive = 0;
+	}
+}
+
+static void handleMonitorEvent(struct HvLpEvent *event)
+{
+	HvLpIndex remoteLp;
+	int i;
+
+	/*
+	 * This handler is _also_ called as part of the loop
+	 * at the end of this routine, so it must be able to
+	 * ignore NULL events...
+	 */
+	if (!event)
+		return;
+
+	/*
+	 * First see if this is just a normal monitor message from the
+	 * other partition
+	 */
+	if (event->xFlags.xFunction == HvLpEvent_Function_Int) {
+		remoteLp = event->xSourceLp;
+		if (!viopathStatus[remoteLp].isActive)
+			sendMonMsg(remoteLp);
+		return;
+	}
+
+	/*
+	 * This path is for an acknowledgement; the other partition
+	 * died
+	 */
+	remoteLp = event->xTargetLp;
+	if ((event->xSourceInstanceId != viopathStatus[remoteLp].mSourceInst) ||
+	    (event->xTargetInstanceId != viopathStatus[remoteLp].mTargetInst)) {
+		printk(VIOPATH_KERN_WARN "ignoring ack....mismatched instances\n");
+		return;
+	}
+
+	printk(VIOPATH_KERN_WARN "partition %d ended\n", remoteLp);
+
+	viopathStatus[remoteLp].isActive = 0;
+
+	/*
+	 * For each active handler, pass them a NULL
+	 * message to indicate that the other partition
+	 * died
+	 */
+	for (i = 0; i < VIO_MAX_SUBTYPES; i++) {
+		if (vio_handler[i] != NULL)
+			(*vio_handler[i])(NULL);
+	}
+}
+
+int vio_setHandler(int subtype, vio_event_handler_t *beh)
+{
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
+		return -EINVAL;
+	if (vio_handler[subtype] != NULL)
+		return -EBUSY;
+	vio_handler[subtype] = beh;
+	return 0;
+}
+EXPORT_SYMBOL(vio_setHandler);
+
+int vio_clearHandler(int subtype)
+{
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
+		return -EINVAL;
+	if (vio_handler[subtype] == NULL)
+		return -EAGAIN;
+	vio_handler[subtype] = NULL;
+	return 0;
+}
+EXPORT_SYMBOL(vio_clearHandler);
+
+static void handleConfig(struct HvLpEvent *event)
+{
+	if (!event)
+		return;
+	if (event->xFlags.xFunction == HvLpEvent_Function_Int) {
+		printk(VIOPATH_KERN_WARN
+		       "unexpected config request from partition %d",
+		       event->xSourceLp);
+
+		if ((event->xFlags.xFunction == HvLpEvent_Function_Int) &&
+		    (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck)) {
+			event->xRc = HvLpEvent_Rc_InvalidSubtype;
+			HvCallEvent_ackLpEvent(event);
+		}
+		return;
+	}
+
+	up((struct semaphore *)event->xCorrelationToken);
+}
+
+/*
+ * Initialization of the hosting partition
+ */
+void vio_set_hostlp(void)
+{
+	/*
+	 * If this has already been set then we DON'T want to either change
+	 * it or re-register the proc file system
+	 */
+	if (viopath_hostLp != HvLpIndexInvalid)
+		return;
+
+	/*
+	 * Figure out our hosting partition.  This isn't allowed to change
+	 * while we're active
+	 */
+	viopath_ourLp = HvLpConfig_getLpIndex();
+	viopath_hostLp = HvLpConfig_getHostingLpIndex(viopath_ourLp);
+
+	if (viopath_hostLp != HvLpIndexInvalid)
+		vio_setHandler(viomajorsubtype_config, handleConfig);
+}
+EXPORT_SYMBOL(vio_set_hostlp);
+
+static void vio_handleEvent(struct HvLpEvent *event, struct pt_regs *regs)
+{
+	HvLpIndex remoteLp;
+	int subtype = (event->xSubtype & VIOMAJOR_SUBTYPE_MASK)
+		>> VIOMAJOR_SUBTYPE_SHIFT;
+
+	if (event->xFlags.xFunction == HvLpEvent_Function_Int) {
+		remoteLp = event->xSourceLp;
+		/*
+		 * The isActive is checked because if the hosting partition
+		 * went down and came back up it would not be active but it
+		 * would have different source and target instances, in which
+		 * case we'd want to reset them.  This case really protects
+		 * against an unauthorized active partition sending interrupts
+		 * or acks to this linux partition.
+		 */
+		if (viopathStatus[remoteLp].isActive
+		    && (event->xSourceInstanceId !=
+			viopathStatus[remoteLp].mTargetInst)) {
+			printk(VIOPATH_KERN_WARN
+			       "message from invalid partition. "
+			       "int msg rcvd, source inst (%d) doesnt match (%d)\n",
+			       viopathStatus[remoteLp].mTargetInst,
+			       event->xSourceInstanceId);
+			return;
+		}
+
+		if (viopathStatus[remoteLp].isActive
+		    && (event->xTargetInstanceId !=
+			viopathStatus[remoteLp].mSourceInst)) {
+			printk(VIOPATH_KERN_WARN
+			       "message from invalid partition. "
+			       "int msg rcvd, target inst (%d) doesnt match (%d)\n",
+			       viopathStatus[remoteLp].mSourceInst,
+			       event->xTargetInstanceId);
+			return;
+		}
+	} else {
+		remoteLp = event->xTargetLp;
+		if (event->xSourceInstanceId !=
+		    viopathStatus[remoteLp].mSourceInst) {
+			printk(VIOPATH_KERN_WARN
+			       "message from invalid partition. "
+			       "ack msg rcvd, source inst (%d) doesnt match (%d)\n",
+			       viopathStatus[remoteLp].mSourceInst,
+			       event->xSourceInstanceId);
+			return;
+		}
+
+		if (event->xTargetInstanceId !=
+		    viopathStatus[remoteLp].mTargetInst) {
+			printk(VIOPATH_KERN_WARN
+			       "message from invalid partition. "
+			       "viopath: ack msg rcvd, target inst (%d) doesnt match (%d)\n",
+			       viopathStatus[remoteLp].mTargetInst,
+			       event->xTargetInstanceId);
+			return;
+		}
+	}
+
+	if (vio_handler[subtype] == NULL) {
+		printk(VIOPATH_KERN_WARN
+		       "unexpected virtual io event subtype %d from partition %d\n",
+		       event->xSubtype, remoteLp);
+		/* No handler.  Ack if necessary */
+		if ((event->xFlags.xFunction == HvLpEvent_Function_Int) &&
+		    (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck)) {
+			event->xRc = HvLpEvent_Rc_InvalidSubtype;
+			HvCallEvent_ackLpEvent(event);
+		}
+		return;
+	}
+
+	/* This innocuous little line is where all the real work happens */
+	(*vio_handler[subtype])(event);
+}
+
+static void viopath_donealloc(void *parm, int number)
+{
+	struct alloc_parms *parmsp = parm;
+
+	parmsp->number = number;
+	if (parmsp->used_wait_atomic)
+		atomic_set(&parmsp->wait_atomic, 0);
+	else
+		up(&parmsp->sem);
+}
+
+static int allocateEvents(HvLpIndex remoteLp, int numEvents)
+{
+	struct alloc_parms parms;
+
+	if (system_state != SYSTEM_RUNNING) {
+		parms.used_wait_atomic = 1;
+		atomic_set(&parms.wait_atomic, 1);
+	} else {
+		parms.used_wait_atomic = 0;
+		init_MUTEX_LOCKED(&parms.sem);
+	}
+	mf_allocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo, 250,	/* It would be nice to put a real number here! */
+			    numEvents, &viopath_donealloc, &parms);
+	if (system_state != SYSTEM_RUNNING) {
+		while (atomic_read(&parms.wait_atomic))
+			mb();
+	} else
+		down(&parms.sem);
+	return parms.number;
+}
+
+int viopath_open(HvLpIndex remoteLp, int subtype, int numReq)
+{
+	int i;
+	unsigned long flags;
+	int tempNumAllocated;
+
+	if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
+		return -EINVAL;
+
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
+		return -EINVAL;
+
+	spin_lock_irqsave(&statuslock, flags);
+
+	if (!event_buffer_initialised) {
+		for (i = 0; i < VIO_MAX_SUBTYPES; i++)
+			atomic_set(&event_buffer_available[i], 1);
+		event_buffer_initialised = 1;
+	}
+
+	viopathStatus[remoteLp].users[subtype]++;
+
+	if (!viopathStatus[remoteLp].isOpen) {
+		viopathStatus[remoteLp].isOpen = 1;
+		HvCallEvent_openLpEventPath(remoteLp, HvLpEvent_Type_VirtualIo);
+
+		/*
+		 * Don't hold the spinlock during an operation that
+		 * can sleep.
+		 */
+		spin_unlock_irqrestore(&statuslock, flags);
+		tempNumAllocated = allocateEvents(remoteLp, 1);
+		spin_lock_irqsave(&statuslock, flags);
+
+		viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
+
+		if (viopathStatus[remoteLp].numberAllocated == 0) {
+			HvCallEvent_closeLpEventPath(remoteLp,
+					HvLpEvent_Type_VirtualIo);
+
+			spin_unlock_irqrestore(&statuslock, flags);
+			return -ENOMEM;
+		}
+
+		viopathStatus[remoteLp].mSourceInst =
+			HvCallEvent_getSourceLpInstanceId(remoteLp,
+					HvLpEvent_Type_VirtualIo);
+		viopathStatus[remoteLp].mTargetInst =
+			HvCallEvent_getTargetLpInstanceId(remoteLp,
+					HvLpEvent_Type_VirtualIo);
+		HvLpEvent_registerHandler(HvLpEvent_Type_VirtualIo,
+					  &vio_handleEvent);
+		sendMonMsg(remoteLp);
+		printk(VIOPATH_KERN_INFO "opening connection to partition %d, "
+				"setting sinst %d, tinst %d\n",
+				remoteLp, viopathStatus[remoteLp].mSourceInst,
+				viopathStatus[remoteLp].mTargetInst);
+	}
+
+	spin_unlock_irqrestore(&statuslock, flags);
+	tempNumAllocated = allocateEvents(remoteLp, numReq);
+	spin_lock_irqsave(&statuslock, flags);
+	viopathStatus[remoteLp].numberAllocated += tempNumAllocated;
+	spin_unlock_irqrestore(&statuslock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL(viopath_open);
+
+int viopath_close(HvLpIndex remoteLp, int subtype, int numReq)
+{
+	unsigned long flags;
+	int i;
+	int numOpen;
+	struct alloc_parms parms;
+
+	if ((remoteLp >= HVMAXARCHITECTEDLPS) || (remoteLp == HvLpIndexInvalid))
+		return -EINVAL;
+
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
+		return -EINVAL;
+
+	spin_lock_irqsave(&statuslock, flags);
+	/*
+	 * If the viopath_close somehow gets called before a
+	 * viopath_open it could decrement to -1 which is a non
+	 * recoverable state so we'll prevent this from
+	 * happening.
+	 */
+	if (viopathStatus[remoteLp].users[subtype] > 0)
+		viopathStatus[remoteLp].users[subtype]--;
+
+	spin_unlock_irqrestore(&statuslock, flags);
+
+	parms.used_wait_atomic = 0;
+	init_MUTEX_LOCKED(&parms.sem);
+	mf_deallocate_lp_events(remoteLp, HvLpEvent_Type_VirtualIo,
+			      numReq, &viopath_donealloc, &parms);
+	down(&parms.sem);
+
+	spin_lock_irqsave(&statuslock, flags);
+	for (i = 0, numOpen = 0; i < VIO_MAX_SUBTYPES; i++)
+		numOpen += viopathStatus[remoteLp].users[i];
+
+	if ((viopathStatus[remoteLp].isOpen) && (numOpen == 0)) {
+		printk(VIOPATH_KERN_INFO "closing connection to partition %d",
+				remoteLp);
+
+		HvCallEvent_closeLpEventPath(remoteLp,
+					     HvLpEvent_Type_VirtualIo);
+		viopathStatus[remoteLp].isOpen = 0;
+		viopathStatus[remoteLp].isActive = 0;
+
+		for (i = 0; i < VIO_MAX_SUBTYPES; i++)
+			atomic_set(&event_buffer_available[i], 0);
+		event_buffer_initialised = 0;
+	}
+	spin_unlock_irqrestore(&statuslock, flags);
+	return 0;
+}
+EXPORT_SYMBOL(viopath_close);
+
+void *vio_get_event_buffer(int subtype)
+{
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES))
+		return NULL;
+
+	if (atomic_dec_if_positive(&event_buffer_available[subtype]) == 0)
+		return &event_buffer[subtype * 256];
+	else
+		return NULL;
+}
+EXPORT_SYMBOL(vio_get_event_buffer);
+
+void vio_free_event_buffer(int subtype, void *buffer)
+{
+	subtype = subtype >> VIOMAJOR_SUBTYPE_SHIFT;
+	if ((subtype < 0) || (subtype >= VIO_MAX_SUBTYPES)) {
+		printk(VIOPATH_KERN_WARN
+		       "unexpected subtype %d freeing event buffer\n", subtype);
+		return;
+	}
+
+	if (atomic_read(&event_buffer_available[subtype]) != 0) {
+		printk(VIOPATH_KERN_WARN
+		       "freeing unallocated event buffer, subtype %d\n",
+		       subtype);
+		return;
+	}
+
+	if (buffer != &event_buffer[subtype * 256]) {
+		printk(VIOPATH_KERN_WARN
+		       "freeing invalid event buffer, subtype %d\n", subtype);
+	}
+
+	atomic_set(&event_buffer_available[subtype], 1);
+}
+EXPORT_SYMBOL(vio_free_event_buffer);
+
+static const struct vio_error_entry vio_no_error =
+    { 0, 0, "Non-VIO Error" };
+static const struct vio_error_entry vio_unknown_error =
+    { 0, EIO, "Unknown Error" };
+
+static const struct vio_error_entry vio_default_errors[] = {
+	{0x0001, EIO, "No Connection"},
+	{0x0002, EIO, "No Receiver"},
+	{0x0003, EIO, "No Buffer Available"},
+	{0x0004, EBADRQC, "Invalid Message Type"},
+	{0x0000, 0, NULL},
+};
+
+const struct vio_error_entry *vio_lookup_rc(
+		const struct vio_error_entry *local_table, u16 rc)
+{
+	const struct vio_error_entry *cur;
+
+	if (!rc)
+		return &vio_no_error;
+	if (local_table)
+		for (cur = local_table; cur->rc; ++cur)
+			if (cur->rc == rc)
+				return cur;
+	for (cur = vio_default_errors; cur->rc; ++cur)
+		if (cur->rc == rc)
+			return cur;
+	return &vio_unknown_error;
+}
+EXPORT_SYMBOL(vio_lookup_rc);