3 * Copyright (c) 2009, Microsoft Corporation.
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
16 * Place - Suite 330, Boston, MA 02111-1307 USA.
19 * Haiyang Zhang <haiyangz@microsoft.com>
20 * Hank Janssen <hjanssen@microsoft.com>
24 #include <linux/kernel.h>
28 #include "ring_buffer.h"
34 /* Amount of space to write to */
35 #define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r)) ? ((z) - ((w) - (r))) : ((r) - (w))
41 GetRingBufferAvailBytes()
44 Get number of bytes available to read and to write to
45 for the specified ring buffer
49 GetRingBufferAvailBytes(struct hv_ring_buffer_info *rbi, u32 *read, u32 *write)
51 u32 read_loc, write_loc;
53 /* Capture the read/write indices before they changed */
54 read_loc = rbi->RingBuffer->ReadIndex;
55 write_loc = rbi->RingBuffer->WriteIndex;
57 *write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->RingDataSize);
58 *read = rbi->RingDataSize - *write;
64 GetNextWriteLocation()
67 Get the next write location for the specified ring buffer
71 GetNextWriteLocation(struct hv_ring_buffer_info *RingInfo)
73 u32 next = RingInfo->RingBuffer->WriteIndex;
75 /* ASSERT(next < RingInfo->RingDataSize); */
83 SetNextWriteLocation()
86 Set the next write location for the specified ring buffer
90 SetNextWriteLocation(struct hv_ring_buffer_info *RingInfo,
91 u32 NextWriteLocation)
93 RingInfo->RingBuffer->WriteIndex = NextWriteLocation;
102 Get the next read location for the specified ring buffer
106 GetNextReadLocation(struct hv_ring_buffer_info *RingInfo)
108 u32 next = RingInfo->RingBuffer->ReadIndex;
110 /* ASSERT(next < RingInfo->RingDataSize); */
118 GetNextReadLocationWithOffset()
121 Get the next read location + offset for the specified ring buffer.
122 This allows the caller to skip
126 GetNextReadLocationWithOffset(struct hv_ring_buffer_info *RingInfo, u32 Offset)
128 u32 next = RingInfo->RingBuffer->ReadIndex;
130 /* ASSERT(next < RingInfo->RingDataSize); */
132 next %= RingInfo->RingDataSize;
140 SetNextReadLocation()
143 Set the next read location for the specified ring buffer
147 SetNextReadLocation(struct hv_ring_buffer_info *RingInfo, u32 NextReadLocation)
149 RingInfo->RingBuffer->ReadIndex = NextReadLocation;
159 Get the start of the ring buffer
163 GetRingBuffer(struct hv_ring_buffer_info *RingInfo)
165 return (void *)RingInfo->RingBuffer->Buffer;
175 Get the size of the ring buffer
179 GetRingBufferSize(struct hv_ring_buffer_info *RingInfo)
181 return RingInfo->RingDataSize;
187 GetRingBufferIndices()
190 Get the read and write indices as u64 of the specified ring buffer
194 GetRingBufferIndices(struct hv_ring_buffer_info *RingInfo)
196 return (u64)RingInfo->RingBuffer->WriteIndex << 32;
206 Dump out to console the ring buffer info
209 void DumpRingInfo(struct hv_ring_buffer_info *RingInfo, char *Prefix)
211 u32 bytesAvailToWrite;
212 u32 bytesAvailToRead;
214 GetRingBufferAvailBytes(RingInfo,
220 "%s <<ringinfo %p buffer %p avail write %u "
221 "avail read %u read idx %u write idx %u>>",
224 RingInfo->RingBuffer->Buffer,
227 RingInfo->RingBuffer->ReadIndex,
228 RingInfo->RingBuffer->WriteIndex);
232 /* Internal routines */
236 struct hv_ring_buffer_info *RingInfo,
237 u32 StartWriteOffset,
243 struct hv_ring_buffer_info *RingInfo,
246 u32 StartReadOffset);
253 RingBufferGetDebugInfo()
256 Get various debug metrics for the specified ring buffer
259 void RingBufferGetDebugInfo(struct hv_ring_buffer_info *RingInfo,
260 struct hv_ring_buffer_debug_info *debug_info)
262 u32 bytesAvailToWrite;
263 u32 bytesAvailToRead;
265 if (RingInfo->RingBuffer) {
266 GetRingBufferAvailBytes(RingInfo,
270 debug_info->BytesAvailToRead = bytesAvailToRead;
271 debug_info->BytesAvailToWrite = bytesAvailToWrite;
272 debug_info->CurrentReadIndex = RingInfo->RingBuffer->ReadIndex;
273 debug_info->CurrentWriteIndex = RingInfo->RingBuffer->WriteIndex;
274 debug_info->CurrentInterruptMask = RingInfo->RingBuffer->InterruptMask;
282 GetRingBufferInterruptMask()
285 Get the interrupt mask for the specified ring buffer
288 u32 GetRingBufferInterruptMask(struct hv_ring_buffer_info *rbi)
290 return rbi->RingBuffer->InterruptMask;
299 Initialize the ring buffer
302 int RingBufferInit(struct hv_ring_buffer_info *RingInfo, void *Buffer, u32 BufferLen)
304 if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
307 memset(RingInfo, 0, sizeof(struct hv_ring_buffer_info));
309 RingInfo->RingBuffer = (struct hv_ring_buffer *)Buffer;
310 RingInfo->RingBuffer->ReadIndex = RingInfo->RingBuffer->WriteIndex = 0;
312 RingInfo->RingSize = BufferLen;
313 RingInfo->RingDataSize = BufferLen - sizeof(struct hv_ring_buffer);
315 spin_lock_init(&RingInfo->ring_lock);
326 Cleanup the ring buffer
329 void RingBufferCleanup(struct hv_ring_buffer_info *RingInfo)
339 Write to the ring buffer
342 int RingBufferWrite(struct hv_ring_buffer_info *OutRingInfo,
343 struct scatterlist *sglist, u32 sgcount)
346 u32 byteAvailToWrite;
348 u32 totalBytesToWrite = 0;
350 struct scatterlist *sg;
351 volatile u32 nextWriteLocation;
355 for_each_sg(sglist, sg, sgcount, i)
357 totalBytesToWrite += sg->length;
360 totalBytesToWrite += sizeof(u64);
362 spin_lock_irqsave(&OutRingInfo->ring_lock, flags);
364 GetRingBufferAvailBytes(OutRingInfo,
368 DPRINT_DBG(VMBUS, "Writing %u bytes...", totalBytesToWrite);
370 /* DumpRingInfo(OutRingInfo, "BEFORE "); */
372 /* If there is only room for the packet, assume it is full. */
373 /* Otherwise, the next time around, we think the ring buffer */
374 /* is empty since the read index == write index */
375 if (byteAvailToWrite <= totalBytesToWrite) {
377 "No more space left on outbound ring buffer "
378 "(needed %u, avail %u)",
382 spin_unlock_irqrestore(&OutRingInfo->ring_lock, flags);
386 /* Write to the ring buffer */
387 nextWriteLocation = GetNextWriteLocation(OutRingInfo);
389 for_each_sg(sglist, sg, sgcount, i)
391 nextWriteLocation = CopyToRingBuffer(OutRingInfo,
397 /* Set previous packet start */
398 prevIndices = GetRingBufferIndices(OutRingInfo);
400 nextWriteLocation = CopyToRingBuffer(OutRingInfo,
405 /* Make sure we flush all writes before updating the writeIndex */
408 /* Now, update the write location */
409 SetNextWriteLocation(OutRingInfo, nextWriteLocation);
411 /* DumpRingInfo(OutRingInfo, "AFTER "); */
413 spin_unlock_irqrestore(&OutRingInfo->ring_lock, flags);
424 Read without advancing the read index
427 int RingBufferPeek(struct hv_ring_buffer_info *InRingInfo, void *Buffer, u32 BufferLen)
429 u32 bytesAvailToWrite;
430 u32 bytesAvailToRead;
431 u32 nextReadLocation = 0;
434 spin_lock_irqsave(&InRingInfo->ring_lock, flags);
436 GetRingBufferAvailBytes(InRingInfo,
440 /* Make sure there is something to read */
441 if (bytesAvailToRead < BufferLen) {
443 "got callback but not enough to read "
444 "<avail to read %d read size %d>!!",
448 spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
453 /* Convert to byte offset */
454 nextReadLocation = GetNextReadLocation(InRingInfo);
456 nextReadLocation = CopyFromRingBuffer(InRingInfo,
461 spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
473 Read and advance the read index
476 int RingBufferRead(struct hv_ring_buffer_info *InRingInfo, void *Buffer,
477 u32 BufferLen, u32 Offset)
479 u32 bytesAvailToWrite;
480 u32 bytesAvailToRead;
481 u32 nextReadLocation = 0;
488 spin_lock_irqsave(&InRingInfo->ring_lock, flags);
490 GetRingBufferAvailBytes(InRingInfo,
494 DPRINT_DBG(VMBUS, "Reading %u bytes...", BufferLen);
496 /* DumpRingInfo(InRingInfo, "BEFORE "); */
498 /* Make sure there is something to read */
499 if (bytesAvailToRead < BufferLen) {
501 "got callback but not enough to read "
502 "<avail to read %d read size %d>!!",
506 spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
511 nextReadLocation = GetNextReadLocationWithOffset(InRingInfo, Offset);
513 nextReadLocation = CopyFromRingBuffer(InRingInfo,
518 nextReadLocation = CopyFromRingBuffer(InRingInfo,
523 /* Make sure all reads are done before we update the read index since */
524 /* the writer may start writing to the read area once the read index */
528 /* Update the read index */
529 SetNextReadLocation(InRingInfo, nextReadLocation);
531 /* DumpRingInfo(InRingInfo, "AFTER "); */
533 spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
545 Helper routine to copy from source to ring buffer.
546 Assume there is enough room. Handles wrap-around in dest case only!!
551 struct hv_ring_buffer_info *RingInfo,
552 u32 StartWriteOffset,
556 void *ringBuffer = GetRingBuffer(RingInfo);
557 u32 ringBufferSize = GetRingBufferSize(RingInfo);
560 /* wrap-around detected! */
561 if (SrcLen > ringBufferSize - StartWriteOffset) {
562 DPRINT_DBG(VMBUS, "wrap-around detected!");
564 fragLen = ringBufferSize - StartWriteOffset;
565 memcpy(ringBuffer + StartWriteOffset, Src, fragLen);
566 memcpy(ringBuffer, Src + fragLen, SrcLen - fragLen);
568 memcpy(ringBuffer + StartWriteOffset, Src, SrcLen);
570 StartWriteOffset += SrcLen;
571 StartWriteOffset %= ringBufferSize;
573 return StartWriteOffset;
583 Helper routine to copy to source from ring buffer.
584 Assume there is enough room. Handles wrap-around in src case only!!
589 struct hv_ring_buffer_info *RingInfo,
594 void *ringBuffer = GetRingBuffer(RingInfo);
595 u32 ringBufferSize = GetRingBufferSize(RingInfo);
599 /* wrap-around detected at the src */
600 if (DestLen > ringBufferSize - StartReadOffset) {
601 DPRINT_DBG(VMBUS, "src wrap-around detected!");
603 fragLen = ringBufferSize - StartReadOffset;
605 memcpy(Dest, ringBuffer + StartReadOffset, fragLen);
606 memcpy(Dest + fragLen, ringBuffer, DestLen - fragLen);
609 memcpy(Dest, ringBuffer + StartReadOffset, DestLen);
612 StartReadOffset += DestLen;
613 StartReadOffset %= ringBufferSize;
615 return StartReadOffset;