1 files changed, 496 insertions, 0 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
new file mode 100644
index 000000000000..8af25a097d75
--- /dev/null
+++ b/drivers/hv/ring_buffer.c
@@ -0,0 +1,496 @@
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/hyperv.h>
+
+#include "hyperv_vmbus.h"
+
+
+/* #defines */
+
+
+/* Amount of space to write to */
+#define BYTES_AVAIL_TO_WRITE(r, w, z) \
+	((w) >= (r)) ? ((z) - ((w) - (r))) : ((r) - (w))
+
+
+/*
+ *
+ * hv_get_ringbuffer_availbytes()
+ *
+ * Get number of bytes available to read and to write to
+ * for the specified ring buffer
+ */
+static inline void
+hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
+			  u32 *read, u32 *write)
+{
+	u32 read_loc, write_loc;
+
+	smp_read_barrier_depends();
+
+	/* Capture the read/write indices before they changed */
+	read_loc = rbi->ring_buffer->read_index;
+	write_loc = rbi->ring_buffer->write_index;
+
+	*write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->ring_datasize);
+	*read = rbi->ring_datasize - *write;
+}
+
+/*
+ * hv_get_next_write_location()
+ *
+ * Get the next write location for the specified ring buffer
+ *
+ */
+static inline u32
+hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
+{
+	u32 next = ring_info->ring_buffer->write_index;
+
+	return next;
+}
+
+/*
+ * hv_set_next_write_location()
+ *
+ * Set the next write location for the specified ring buffer
+ *
+ */
+static inline void
+hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
+		     u32 next_write_location)
+{
+	ring_info->ring_buffer->write_index = next_write_location;
+}
+
+/*
+ * hv_get_next_read_location()
+ *
+ * Get the next read location for the specified ring buffer
+ */
+static inline u32
+hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
+{
+	u32 next = ring_info->ring_buffer->read_index;
+
+	return next;
+}
+
+/*
+ * hv_get_next_readlocation_withoffset()
+ *
+ * Get the next read location + offset for the specified ring buffer.
+ * This allows the caller to skip
+ */
+static inline u32
+hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
+				 u32 offset)
+{
+	u32 next = ring_info->ring_buffer->read_index;
+
+	next += offset;
+	next %= ring_info->ring_datasize;
+
+	return next;
+}
+
+/*
+ *
+ * hv_set_next_read_location()
+ *
+ * Set the next read location for the specified ring buffer
+ *
+ */
+static inline void
+hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
+		    u32 next_read_location)
+{
+	ring_info->ring_buffer->read_index = next_read_location;
+}
+
+
+/*
+ *
+ * hv_get_ring_buffer()
+ *
+ * Get the start of the ring buffer
+ */
+static inline void *
+hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
+{
+	return (void *)ring_info->ring_buffer->buffer;
+}
+
+
+/*
+ *
+ * hv_get_ring_buffersize()
+ *
+ * Get the size of the ring buffer
+ */
+static inline u32
+hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
+{
+	return ring_info->ring_datasize;
+}
+
+/*
+ *
+ * hv_get_ring_bufferindices()
+ *
+ * Get the read and write indices as u64 of the specified ring buffer
+ *
+ */
+static inline u64
+hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
+{
+	return (u64)ring_info->ring_buffer->write_index << 32;
+}
+
+/*
+ *
+ * hv_copyfrom_ringbuffer()
+ *
+ * Helper routine to copy to source from ring buffer.
+ * Assume there is enough room. Handles wrap-around in src case only!!
+ *
+ */
+static u32 hv_copyfrom_ringbuffer(
+	struct hv_ring_buffer_info	*ring_info,
+	void				*dest,
+	u32				destlen,
+	u32				start_read_offset)
+{
+	void *ring_buffer = hv_get_ring_buffer(ring_info);
+	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
+
+	u32 frag_len;
+
+	/* wrap-around detected at the src */
+	if (destlen > ring_buffer_size - start_read_offset) {
+		frag_len = ring_buffer_size - start_read_offset;
+
+		memcpy(dest, ring_buffer + start_read_offset, frag_len);
+		memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
+	} else
+
+		memcpy(dest, ring_buffer + start_read_offset, destlen);
+
+
+	start_read_offset += destlen;
+	start_read_offset %= ring_buffer_size;
+
+	return start_read_offset;
+}
+
+
+/*
+ *
+ * hv_copyto_ringbuffer()
+ *
+ * Helper routine to copy from source to ring buffer.
+ * Assume there is enough room. Handles wrap-around in dest case only!!
+ *
+ */
+static u32 hv_copyto_ringbuffer(
+	struct hv_ring_buffer_info	*ring_info,
+	u32				start_write_offset,
+	void				*src,
+	u32				srclen)
+{
+	void *ring_buffer = hv_get_ring_buffer(ring_info);
+	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
+	u32 frag_len;
+
+	/* wrap-around detected! */
+	if (srclen > ring_buffer_size - start_write_offset) {
+		frag_len = ring_buffer_size - start_write_offset;
+		memcpy(ring_buffer + start_write_offset, src, frag_len);
+		memcpy(ring_buffer, src + frag_len, srclen - frag_len);
+	} else
+		memcpy(ring_buffer + start_write_offset, src, srclen);
+
+	start_write_offset += srclen;
+	start_write_offset %= ring_buffer_size;
+
+	return start_write_offset;
+}
+
+/*
+ *
+ * hv_ringbuffer_get_debuginfo()
+ *
+ * Get various debug metrics for the specified ring buffer
+ *
+ */
+void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
+			    struct hv_ring_buffer_debug_info *debug_info)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+
+	if (ring_info->ring_buffer) {
+		hv_get_ringbuffer_availbytes(ring_info,
+					&bytes_avail_toread,
+					&bytes_avail_towrite);
+
+		debug_info->bytes_avail_toread = bytes_avail_toread;
+		debug_info->bytes_avail_towrite = bytes_avail_towrite;
+		debug_info->current_read_index =
+			ring_info->ring_buffer->read_index;
+		debug_info->current_write_index =
+			ring_info->ring_buffer->write_index;
+		debug_info->current_interrupt_mask =
+			ring_info->ring_buffer->interrupt_mask;
+	}
+}
+
+
+/*
+ *
+ * hv_get_ringbuffer_interrupt_mask()
+ *
+ * Get the interrupt mask for the specified ring buffer
+ *
+ */
+u32 hv_get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *rbi)
+{
+	return rbi->ring_buffer->interrupt_mask;
+}
+
+/*
+ *
+ * hv_ringbuffer_init()
+ *
+ *Initialize the ring buffer
+ *
+ */
+int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
+		   void *buffer, u32 buflen)
+{
+	if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
+		return -EINVAL;
+
+	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
+
+	ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
+	ring_info->ring_buffer->read_index =
+		ring_info->ring_buffer->write_index = 0;
+
+	ring_info->ring_size = buflen;
+	ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
+
+	spin_lock_init(&ring_info->ring_lock);
+
+	return 0;
+}
+
+/*
+ *
+ * hv_ringbuffer_cleanup()
+ *
+ * Cleanup the ring buffer
+ *
+ */
+void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
+{
+}
+
+/*
+ *
+ * hv_ringbuffer_write()
+ *
+ * Write to the ring buffer
+ *
+ */
+int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
+		    struct scatterlist *sglist, u32 sgcount)
+{
+	int i = 0;
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 totalbytes_towrite = 0;
+
+	struct scatterlist *sg;
+	u32 next_write_location;
+	u64 prev_indices = 0;
+	unsigned long flags;
+
+	for_each_sg(sglist, sg, sgcount, i)
+	{
+		totalbytes_towrite += sg->length;
+	}
+
+	totalbytes_towrite += sizeof(u64);
+
+	spin_lock_irqsave(&outring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(outring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+
+	/* If there is only room for the packet, assume it is full. */
+	/* Otherwise, the next time around, we think the ring buffer */
+	/* is empty since the read index == write index */
+	if (bytes_avail_towrite <= totalbytes_towrite) {
+		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+		return -EAGAIN;
+	}
+
+	/* Write to the ring buffer */
+	next_write_location = hv_get_next_write_location(outring_info);
+
+	for_each_sg(sglist, sg, sgcount, i)
+	{
+		next_write_location = hv_copyto_ringbuffer(outring_info,
+						     next_write_location,
+						     sg_virt(sg),
+						     sg->length);
+	}
+
+	/* Set previous packet start */
+	prev_indices = hv_get_ring_bufferindices(outring_info);
+
+	next_write_location = hv_copyto_ringbuffer(outring_info,
+					     next_write_location,
+					     &prev_indices,
+					     sizeof(u64));
+
+	/* Make sure we flush all writes before updating the writeIndex */
+	smp_wmb();
+
+	/* Now, update the write location */
+	hv_set_next_write_location(outring_info, next_write_location);
+
+
+	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+	return 0;
+}
+
+
+/*
+ *
+ * hv_ringbuffer_peek()
+ *
+ * Read without advancing the read index
+ *
+ */
+int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
+		   void *Buffer, u32 buflen)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 next_read_location = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&Inring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(Inring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+	/* Make sure there is something to read */
+	if (bytes_avail_toread < buflen) {
+
+		spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
+
+		return -EAGAIN;
+	}
+
+	/* Convert to byte offset */
+	next_read_location = hv_get_next_read_location(Inring_info);
+
+	next_read_location = hv_copyfrom_ringbuffer(Inring_info,
+						Buffer,
+						buflen,
+						next_read_location);
+
+	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
+
+	return 0;
+}
+
+
+/*
+ *
+ * hv_ringbuffer_read()
+ *
+ * Read and advance the read index
+ *
+ */
+int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
+		   u32 buflen, u32 offset)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 next_read_location = 0;
+	u64 prev_indices = 0;
+	unsigned long flags;
+
+	if (buflen <= 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&inring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(inring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+	/* Make sure there is something to read */
+	if (bytes_avail_toread < buflen) {
+		spin_unlock_irqrestore(&inring_info->ring_lock, flags);
+
+		return -EAGAIN;
+	}
+
+	next_read_location =
+		hv_get_next_readlocation_withoffset(inring_info, offset);
+
+	next_read_location = hv_copyfrom_ringbuffer(inring_info,
+						buffer,
+						buflen,
+						next_read_location);
+
+	next_read_location = hv_copyfrom_ringbuffer(inring_info,
+						&prev_indices,
+						sizeof(u64),
+						next_read_location);
+
+	/* Make sure all reads are done before we update the read index since */
+	/* the writer may start writing to the read area once the read index */
+	/*is updated */
+	smp_mb();
+
+	/* Update the read index */
+	hv_set_next_read_location(inring_info, next_read_location);
+
+	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
+
+	return 0;
+}