[deliverable/linux.git] / drivers / staging / hv / ring_buffer.c

/*
 *
 * 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>
 *
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include "logging.h"
#include "ring_buffer.h"


/* #defines */


/* Amount of space to write to */
#define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r)) ? ((z) - ((w) - (r))) : ((r) - (w))


/*++

Name:
	get_ringbuffer_availbytes()

Description:
	Get number of bytes available to read and to write to
	for the specified ring buffer

--*/
static inline void
get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
			  u32 *read, u32 *write)
{
	u32 read_loc, write_loc;

	/* 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;
}

/*++

Name:
	get_next_write_location()

Description:
	Get the next write location for the specified ring buffer

--*/
static inline u32
get_next_write_location(struct hv_ring_buffer_info *ring_info)
{
	u32 next = ring_info->ring_buffer->write_index;

	/* ASSERT(next < ring_info->RingDataSize); */

	return next;
}

/*++

Name:
	set_next_write_location()

Description:
	Set the next write location for the specified ring buffer

--*/
static inline void
set_next_write_location(struct hv_ring_buffer_info *ring_info,
		     u32 next_write_location)
{
	ring_info->ring_buffer->write_index = next_write_location;
}

/*++

Name:
	get_next_read_location()

Description:
	Get the next read location for the specified ring buffer

--*/
static inline u32
get_next_read_location(struct hv_ring_buffer_info *ring_info)
{
	u32 next = ring_info->ring_buffer->read_index;

	/* ASSERT(next < ring_info->RingDataSize); */

	return next;
}

/*++

Name:
	get_next_readlocation_withoffset()

Description:
	Get the next read location + offset for the specified ring buffer.
	This allows the caller to skip

--*/
static inline u32
get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
				 u32 offset)
{
	u32 next = ring_info->ring_buffer->read_index;

	/* ASSERT(next < ring_info->RingDataSize); */
	next += offset;
	next %= ring_info->ring_datasize;

	return next;
}

/*++

Name:
	set_next_read_location()

Description:
	Set the next read location for the specified ring buffer

--*/
static inline void
set_next_read_location(struct hv_ring_buffer_info *ring_info,
		    u32 next_read_location)
{
	ring_info->ring_buffer->read_index = next_read_location;
}


/*++

Name:
	get_ring_buffer()

Description:
	Get the start of the ring buffer

--*/
static inline void *
get_ring_buffer(struct hv_ring_buffer_info *ring_info)
{
	return (void *)ring_info->ring_buffer->buffer;
}


/*++

Name:
	get_ring_buffersize()

Description:
	Get the size of the ring buffer

--*/
static inline u32
get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
{
	return ring_info->ring_datasize;
}

/*++

Name:
	get_ring_bufferindices()

Description:
	Get the read and write indices as u64 of the specified ring buffer

--*/
static inline u64
get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
{
	return (u64)ring_info->ring_buffer->write_index << 32;
}


/*++

Name:
	dump_ring_info()

Description:
	Dump out to console the ring buffer info

--*/
void dump_ring_info(struct hv_ring_buffer_info *ring_info, char *prefix)
{
	u32 bytes_avail_towrite;
	u32 bytes_avail_toread;

	get_ringbuffer_availbytes(ring_info,
	&bytes_avail_toread,
	&bytes_avail_towrite);

	DPRINT(VMBUS,
		DEBUG_RING_LVL,
		"%s <<ringinfo %p buffer %p avail write %u "
		"avail read %u read idx %u write idx %u>>",
		prefix,
		ring_info,
		ring_info->ring_buffer->buffer,
		bytes_avail_towrite,
		bytes_avail_toread,
		ring_info->ring_buffer->read_index,
		ring_info->ring_buffer->write_index);
}


/* Internal routines */

static u32
copyto_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	u32				start_write_offset,
	void				*src,
	u32				srclen);

static u32
copyfrom_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	void				*dest,
	u32				destlen,
	u32				start_read_offset);


/*++

Name:
	ringbuffer_get_debuginfo()

Description:
	Get various debug metrics for the specified ring buffer

--*/
void 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) {
		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;
	}
}


/*++

Name:
	get_ringbuffer_interrupt_mask()

Description:
	Get the interrupt mask for the specified ring buffer

--*/
u32 get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *rbi)
{
	return rbi->ring_buffer->interrupt_mask;
}

/*++

Name:
	ringbuffer_init()

Description:
	Initialize the ring buffer

--*/
int 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;
}

/*++

Name:
	ringbuffer_cleanup()

Description:
	Cleanup the ring buffer

--*/
void ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
{
}

/*++

Name:
	ringbuffer_write()

Description:
	Write to the ring buffer

--*/
int 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;
	volatile 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);

	get_ringbuffer_availbytes(outring_info,
				&bytes_avail_toread,
				&bytes_avail_towrite);

	/* Dumpring_info(Outring_info, "BEFORE "); */

	/* 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 -1;
	}

	/* Write to the ring buffer */
	next_write_location = get_next_write_location(outring_info);

	for_each_sg(sglist, sg, sgcount, i)
	{
		next_write_location = copyto_ringbuffer(outring_info,
						     next_write_location,
						     sg_virt(sg),
						     sg->length);
	}

	/* Set previous packet start */
	prev_indices = get_ring_bufferindices(outring_info);

	next_write_location = copyto_ringbuffer(outring_info,
					     next_write_location,
					     &prev_indices,
					     sizeof(u64));

	/* Make sure we flush all writes before updating the writeIndex */
	mb();

	/* Now, update the write location */
	set_next_write_location(outring_info, next_write_location);

	/* Dumpring_info(Outring_info, "AFTER "); */

	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
	return 0;
}


/*++

Name:
	ringbuffer_peek()

Description:
	Read without advancing the read index

--*/
int 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);

	get_ringbuffer_availbytes(Inring_info,
				&bytes_avail_toread,
				&bytes_avail_towrite);

	/* Make sure there is something to read */
	if (bytes_avail_toread < buflen) {
		/* DPRINT_DBG(VMBUS,
			"got callback but not enough to read "
			"<avail to read %d read size %d>!!",
			bytes_avail_toread,
			BufferLen); */

		spin_unlock_irqrestore(&Inring_info->ring_lock, flags);

		return -1;
	}

	/* Convert to byte offset */
	next_read_location = get_next_read_location(Inring_info);

	next_read_location = copyfrom_ringbuffer(Inring_info,
						Buffer,
						buflen,
						next_read_location);

	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);

	return 0;
}


/*++

Name:
	ringbuffer_read()

Description:
	Read and advance the read index

--*/
int 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);

	get_ringbuffer_availbytes(inring_info,
				&bytes_avail_toread,
				&bytes_avail_towrite);

	/* Dumpring_info(Inring_info, "BEFORE "); */

	/* Make sure there is something to read */
	if (bytes_avail_toread < buflen) {
		spin_unlock_irqrestore(&inring_info->ring_lock, flags);

		return -1;
	}

	next_read_location =
		get_next_readlocation_withoffset(inring_info, offset);

	next_read_location = copyfrom_ringbuffer(inring_info,
						buffer,
						buflen,
						next_read_location);

	next_read_location = 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 */
	mb();

	/* Update the read index */
	set_next_read_location(inring_info, next_read_location);

	/* Dumpring_info(Inring_info, "AFTER "); */

	spin_unlock_irqrestore(&inring_info->ring_lock, flags);

	return 0;
}


/*++

Name:
	copyto_ringbuffer()

Description:
	Helper routine to copy from source to ring buffer.
	Assume there is enough room. Handles wrap-around in dest case only!!

--*/
static u32
copyto_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	u32				start_write_offset,
	void				*src,
	u32				srclen)
{
	void *ring_buffer = get_ring_buffer(ring_info);
	u32 ring_buffer_size = 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;
}


/*++

Name:
	copyfrom_ringbuffer()

Description:
	Helper routine to copy to source from ring buffer.
	Assume there is enough room. Handles wrap-around in src case only!!

--*/
static u32
copyfrom_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	void				*dest,
	u32				destlen,
	u32				start_read_offset)
{
	void *ring_buffer = get_ring_buffer(ring_info);
	u32 ring_buffer_size = 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;
}


/* eof */
Commit	Line	Data
3e7ee490 HJ	1	/*
	2	*
	3	* Copyright (c) 2009, Microsoft Corporation.
	4	*
	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.
	8	*
	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
	12	* more details.
	13	*
	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.
	17	*
	18	* Authors:
	19	* Haiyang Zhang <haiyangz@microsoft.com>
	20	* Hank Janssen <hjanssen@microsoft.com>
	21	*
	22	*/
	23
a0086dc5 GKH	24	#include <linux/kernel.h>
a0086dc5 GKH	25	#include <linux/mm.h>
645954c5	26	#include "logging.h"
8f078ca6	27	#include "ring_buffer.h"
3e7ee490	28
3e7ee490	29
454f18a9 BP	30	/* #defines */
	31
	32
	33	/* Amount of space to write to */
0686e4f4	34	#define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r)) ? ((z) - ((w) - (r))) : ((r) - (w))
3e7ee490 HJ	35
	36
	37	/*++
	38
	39	Name:
1ac58644	40	get_ringbuffer_availbytes()
3e7ee490 HJ	41
	42	Description:
	43	Get number of bytes available to read and to write to
	44	for the specified ring buffer
	45
	46	--*/
	47	static inline void
1ac58644 HZ	48	get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
1ac58644 HZ	49	u32 read, u32 write)
3e7ee490	50	{
4408f531	51	u32 read_loc, write_loc;
3e7ee490	52
454f18a9	53	/* Capture the read/write indices before they changed */
82f8bd40 HZ	54	read_loc = rbi->ring_buffer->read_index;
82f8bd40 HZ	55	write_loc = rbi->ring_buffer->write_index;
3e7ee490	56
82f8bd40 HZ	57	*write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->ring_datasize);
82f8bd40 HZ	58	read = rbi->ring_datasize - write;
3e7ee490 HJ	59	}
	60
	61	/*++
	62
	63	Name:
1ac58644	64	get_next_write_location()
3e7ee490 HJ	65
	66	Description:
	67	Get the next write location for the specified ring buffer
	68
	69	--*/
4d643114	70	static inline u32
1ac58644	71	get_next_write_location(struct hv_ring_buffer_info *ring_info)
3e7ee490	72	{
fc8c72eb	73	u32 next = ring_info->ring_buffer->write_index;
3e7ee490	74
fc8c72eb	75	/* ASSERT(next < ring_info->RingDataSize); */
3e7ee490 HJ	76
	77	return next;
	78	}
	79
	80	/*++
	81
	82	Name:
1ac58644	83	set_next_write_location()
3e7ee490 HJ	84
	85	Description:
	86	Set the next write location for the specified ring buffer
	87
	88	--*/
	89	static inline void
1ac58644	90	set_next_write_location(struct hv_ring_buffer_info *ring_info,
fc8c72eb	91	u32 next_write_location)
3e7ee490	92	{
fc8c72eb	93	ring_info->ring_buffer->write_index = next_write_location;
3e7ee490 HJ	94	}
	95
	96	/*++
	97
	98	Name:
1ac58644	99	get_next_read_location()
3e7ee490 HJ	100
	101	Description:
	102	Get the next read location for the specified ring buffer
	103
	104	--*/
4d643114	105	static inline u32
1ac58644	106	get_next_read_location(struct hv_ring_buffer_info *ring_info)
3e7ee490	107	{
fc8c72eb	108	u32 next = ring_info->ring_buffer->read_index;
3e7ee490	109
fc8c72eb	110	/* ASSERT(next < ring_info->RingDataSize); */
3e7ee490 HJ	111
	112	return next;
	113	}
	114
	115	/*++
	116
	117	Name:
1ac58644	118	get_next_readlocation_withoffset()
3e7ee490 HJ	119
	120	Description:
	121	Get the next read location + offset for the specified ring buffer.
	122	This allows the caller to skip
	123
	124	--*/
4d643114	125	static inline u32
1ac58644 HZ	126	get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
1ac58644 HZ	127	u32 offset)
3e7ee490	128	{
fc8c72eb	129	u32 next = ring_info->ring_buffer->read_index;
3e7ee490	130
fc8c72eb HZ	131	/* ASSERT(next < ring_info->RingDataSize); */
	132	next += offset;
	133	next %= ring_info->ring_datasize;
3e7ee490 HJ	134
	135	return next;
	136	}
	137
	138	/*++
	139
	140	Name:
1ac58644	141	set_next_read_location()
3e7ee490 HJ	142
	143	Description:
	144	Set the next read location for the specified ring buffer
	145
	146	--*/
	147	static inline void
1ac58644	148	set_next_read_location(struct hv_ring_buffer_info *ring_info,
fc8c72eb	149	u32 next_read_location)
3e7ee490	150	{
fc8c72eb	151	ring_info->ring_buffer->read_index = next_read_location;
3e7ee490 HJ	152	}
	153
	154
	155	/*++
	156
	157	Name:
1ac58644	158	get_ring_buffer()
3e7ee490 HJ	159
	160	Description:
	161	Get the start of the ring buffer
	162
	163	--*/
8282c400	164	static inline void *
1ac58644	165	get_ring_buffer(struct hv_ring_buffer_info *ring_info)
3e7ee490	166	{
fc8c72eb	167	return (void *)ring_info->ring_buffer->buffer;
3e7ee490 HJ	168	}
	169
	170
	171	/*++
	172
	173	Name:
1ac58644	174	get_ring_buffersize()
3e7ee490 HJ	175
	176	Description:
	177	Get the size of the ring buffer
	178
	179	--*/
4d643114	180	static inline u32
1ac58644	181	get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
3e7ee490	182	{
fc8c72eb	183	return ring_info->ring_datasize;
3e7ee490 HJ	184	}
	185
	186	/*++
	187
	188	Name:
1ac58644	189	get_ring_bufferindices()
3e7ee490 HJ	190
3e7ee490 HJ	191	Description:
59471438	192	Get the read and write indices as u64 of the specified ring buffer
3e7ee490 HJ	193
3e7ee490 HJ	194	--*/
59471438	195	static inline u64
1ac58644	196	get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
3e7ee490	197	{
fc8c72eb	198	return (u64)ring_info->ring_buffer->write_index << 32;
3e7ee490 HJ	199	}
	200
	201
	202	/*++
	203
	204	Name:
1ac58644	205	dump_ring_info()
3e7ee490 HJ	206
	207	Description:
	208	Dump out to console the ring buffer info
	209
	210	--*/
1ac58644	211	void dump_ring_info(struct hv_ring_buffer_info ring_info, char prefix)
3e7ee490	212	{
fc8c72eb HZ	213	u32 bytes_avail_towrite;
fc8c72eb HZ	214	u32 bytes_avail_toread;
3e7ee490	215
1ac58644	216	get_ringbuffer_availbytes(ring_info,
fc8c72eb HZ	217	&bytes_avail_toread,
fc8c72eb HZ	218	&bytes_avail_towrite);
3e7ee490	219
4408f531 B	220	DPRINT(VMBUS,
	221	DEBUG_RING_LVL,
	222	"%s <<ringinfo %p buffer %p avail write %u "
	223	"avail read %u read idx %u write idx %u>>",
fc8c72eb HZ	224	prefix,
	225	ring_info,
	226	ring_info->ring_buffer->buffer,
	227	bytes_avail_towrite,
	228	bytes_avail_toread,
	229	ring_info->ring_buffer->read_index,
	230	ring_info->ring_buffer->write_index);
3e7ee490 HJ	231	}
3e7ee490 HJ	232
454f18a9 BP	233
	234	/* Internal routines */
	235
4d643114	236	static u32
1ac58644	237	copyto_ringbuffer(
fc8c72eb HZ	238	struct hv_ring_buffer_info *ring_info,
	239	u32 start_write_offset,
	240	void *src,
	241	u32 srclen);
3e7ee490	242
4d643114	243	static u32
1ac58644	244	copyfrom_ringbuffer(
fc8c72eb HZ	245	struct hv_ring_buffer_info *ring_info,
	246	void *dest,
	247	u32 destlen,
	248	u32 start_read_offset);
3e7ee490 HJ	249
	250
	251
	252	/*++
	253
	254	Name:
1ac58644	255	ringbuffer_get_debuginfo()
3e7ee490 HJ	256
	257	Description:
	258	Get various debug metrics for the specified ring buffer
	259
	260	--*/
1ac58644	261	void ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
80682b7a	262	struct hv_ring_buffer_debug_info *debug_info)
3e7ee490	263	{
fc8c72eb HZ	264	u32 bytes_avail_towrite;
fc8c72eb HZ	265	u32 bytes_avail_toread;
3e7ee490	266
fc8c72eb	267	if (ring_info->ring_buffer) {
1ac58644	268	get_ringbuffer_availbytes(ring_info,
fc8c72eb HZ	269	&bytes_avail_toread,
fc8c72eb HZ	270	&bytes_avail_towrite);
3e7ee490	271
fc8c72eb HZ	272	debug_info->bytes_avail_toread = bytes_avail_toread;
fc8c72eb HZ	273	debug_info->bytes_avail_towrite = bytes_avail_towrite;
82f8bd40	274	debug_info->current_read_index =
fc8c72eb	275	ring_info->ring_buffer->read_index;
82f8bd40	276	debug_info->current_write_index =
fc8c72eb	277	ring_info->ring_buffer->write_index;
82f8bd40	278	debug_info->current_interrupt_mask =
fc8c72eb	279	ring_info->ring_buffer->interrupt_mask;
3e7ee490 HJ	280	}
	281	}
	282
	283
	284	/*++
	285
	286	Name:
1ac58644	287	get_ringbuffer_interrupt_mask()
3e7ee490 HJ	288
	289	Description:
	290	Get the interrupt mask for the specified ring buffer
	291
	292	--*/
1ac58644	293	u32 get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *rbi)
3e7ee490	294	{
82f8bd40	295	return rbi->ring_buffer->interrupt_mask;
3e7ee490 HJ	296	}
	297
	298	/*++
	299
	300	Name:
1ac58644	301	ringbuffer_init()
3e7ee490 HJ	302
	303	Description:
	304	Initialize the ring buffer
	305
	306	--*/
1ac58644	307	int ringbuffer_init(struct hv_ring_buffer_info *ring_info,
fc8c72eb	308	void *buffer, u32 buflen)
3e7ee490	309	{
4a1b3acc	310	if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
3324fb40	311	return -EINVAL;
3e7ee490	312
fc8c72eb	313	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
3e7ee490	314
fc8c72eb HZ	315	ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
	316	ring_info->ring_buffer->read_index =
	317	ring_info->ring_buffer->write_index = 0;
3e7ee490	318
fc8c72eb HZ	319	ring_info->ring_size = buflen;
fc8c72eb HZ	320	ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
3e7ee490	321
fc8c72eb	322	spin_lock_init(&ring_info->ring_lock);
3e7ee490 HJ	323
	324	return 0;
	325	}
	326
	327	/*++
	328
	329	Name:
1ac58644	330	ringbuffer_cleanup()
3e7ee490 HJ	331
	332	Description:
	333	Cleanup the ring buffer
	334
	335	--*/
1ac58644	336	void ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
3e7ee490	337	{
3e7ee490 HJ	338	}
	339
	340	/*++
	341
	342	Name:
1ac58644	343	ringbuffer_write()
3e7ee490 HJ	344
	345	Description:
	346	Write to the ring buffer
	347
	348	--*/
1ac58644	349	int ringbuffer_write(struct hv_ring_buffer_info *outring_info,
3523a805	350	struct scatterlist *sglist, u32 sgcount)
3e7ee490	351	{
4408f531	352	int i = 0;
fc8c72eb HZ	353	u32 bytes_avail_towrite;
	354	u32 bytes_avail_toread;
	355	u32 totalbytes_towrite = 0;
3e7ee490	356
b219b3f7	357	struct scatterlist *sg;
fc8c72eb HZ	358	volatile u32 next_write_location;
fc8c72eb HZ	359	u64 prev_indices = 0;
a98f96ee	360	unsigned long flags;
3e7ee490	361
b219b3f7	362	for_each_sg(sglist, sg, sgcount, i)
3e7ee490	363	{
fc8c72eb	364	totalbytes_towrite += sg->length;
3e7ee490 HJ	365	}
3e7ee490 HJ	366
fc8c72eb	367	totalbytes_towrite += sizeof(u64);
3e7ee490	368
fc8c72eb	369	spin_lock_irqsave(&outring_info->ring_lock, flags);
3e7ee490	370
1ac58644	371	get_ringbuffer_availbytes(outring_info,
fc8c72eb HZ	372	&bytes_avail_toread,
fc8c72eb HZ	373	&bytes_avail_towrite);
3e7ee490	374
fc8c72eb	375	/* Dumpring_info(Outring_info, "BEFORE "); */
3e7ee490	376
4408f531 B	377	/* If there is only room for the packet, assume it is full. */
4408f531 B	378	/* Otherwise, the next time around, we think the ring buffer */
454f18a9	379	/* is empty since the read index == write index */
fc8c72eb	380	if (bytes_avail_towrite <= totalbytes_towrite) {
fc8c72eb	381	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
3e7ee490 HJ	382	return -1;
	383	}
	384
454f18a9	385	/* Write to the ring buffer */
1ac58644	386	next_write_location = get_next_write_location(outring_info);
3e7ee490	387
b219b3f7	388	for_each_sg(sglist, sg, sgcount, i)
3e7ee490	389	{
1ac58644	390	next_write_location = copyto_ringbuffer(outring_info,
fc8c72eb	391	next_write_location,
b219b3f7 NP	392	sg_virt(sg),
b219b3f7 NP	393	sg->length);
3e7ee490 HJ	394	}
3e7ee490 HJ	395
454f18a9	396	/* Set previous packet start */
1ac58644	397	prev_indices = get_ring_bufferindices(outring_info);
3e7ee490	398
1ac58644	399	next_write_location = copyto_ringbuffer(outring_info,
fc8c72eb HZ	400	next_write_location,
fc8c72eb HZ	401	&prev_indices,
b219b3f7	402	sizeof(u64));
3e7ee490	403
454f18a9	404	/* Make sure we flush all writes before updating the writeIndex */
28b6ca9c	405	mb();
3e7ee490	406
454f18a9	407	/* Now, update the write location */
1ac58644	408	set_next_write_location(outring_info, next_write_location);
3e7ee490	409
fc8c72eb	410	/* Dumpring_info(Outring_info, "AFTER "); */
3e7ee490	411
fc8c72eb	412	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
3e7ee490 HJ	413	return 0;
	414	}
	415
	416
	417	/*++
	418
	419	Name:
1ac58644	420	ringbuffer_peek()
3e7ee490 HJ	421
	422	Description:
	423	Read without advancing the read index
	424
	425	--*/
1ac58644	426	int ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
fc8c72eb	427	void *Buffer, u32 buflen)
3e7ee490	428	{
fc8c72eb HZ	429	u32 bytes_avail_towrite;
	430	u32 bytes_avail_toread;
	431	u32 next_read_location = 0;
a98f96ee	432	unsigned long flags;
3e7ee490	433
fc8c72eb	434	spin_lock_irqsave(&Inring_info->ring_lock, flags);
3e7ee490	435
1ac58644	436	get_ringbuffer_availbytes(Inring_info,
fc8c72eb HZ	437	&bytes_avail_toread,
fc8c72eb HZ	438	&bytes_avail_towrite);
3e7ee490	439
454f18a9	440	/* Make sure there is something to read */
fc8c72eb	441	if (bytes_avail_toread < buflen) {
4408f531 B	442	/* DPRINT_DBG(VMBUS,
	443	"got callback but not enough to read "
	444	"<avail to read %d read size %d>!!",
fc8c72eb	445	bytes_avail_toread,
4408f531	446	BufferLen); */
3e7ee490	447
fc8c72eb	448	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
3e7ee490 HJ	449
	450	return -1;
	451	}
	452
454f18a9	453	/* Convert to byte offset */
1ac58644	454	next_read_location = get_next_read_location(Inring_info);
3e7ee490	455
1ac58644	456	next_read_location = copyfrom_ringbuffer(Inring_info,
4408f531	457	Buffer,
fc8c72eb HZ	458	buflen,
fc8c72eb HZ	459	next_read_location);
3e7ee490	460
fc8c72eb	461	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
3e7ee490 HJ	462
	463	return 0;
	464	}
	465
	466
	467	/*++
	468
	469	Name:
1ac58644	470	ringbuffer_read()
3e7ee490 HJ	471
	472	Description:
	473	Read and advance the read index
	474
	475	--*/
1ac58644	476	int ringbuffer_read(struct hv_ring_buffer_info inring_info, void buffer,
fc8c72eb	477	u32 buflen, u32 offset)
3e7ee490	478	{
fc8c72eb HZ	479	u32 bytes_avail_towrite;
	480	u32 bytes_avail_toread;
	481	u32 next_read_location = 0;
	482	u64 prev_indices = 0;
a98f96ee	483	unsigned long flags;
3e7ee490	484
fc8c72eb	485	if (buflen <= 0)
a16e1485	486	return -EINVAL;
3e7ee490	487
fc8c72eb	488	spin_lock_irqsave(&inring_info->ring_lock, flags);
3e7ee490	489
1ac58644	490	get_ringbuffer_availbytes(inring_info,
fc8c72eb HZ	491	&bytes_avail_toread,
fc8c72eb HZ	492	&bytes_avail_towrite);
3e7ee490	493
fc8c72eb	494	/* Dumpring_info(Inring_info, "BEFORE "); */
3e7ee490	495
454f18a9	496	/* Make sure there is something to read */
fc8c72eb	497	if (bytes_avail_toread < buflen) {
fc8c72eb	498	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
3e7ee490 HJ	499
	500	return -1;
	501	}
	502
1ac58644 HZ	503	next_read_location =
1ac58644 HZ	504	get_next_readlocation_withoffset(inring_info, offset);
3e7ee490	505
1ac58644	506	next_read_location = copyfrom_ringbuffer(inring_info,
fc8c72eb HZ	507	buffer,
	508	buflen,
	509	next_read_location);
3e7ee490	510
1ac58644	511	next_read_location = copyfrom_ringbuffer(inring_info,
fc8c72eb	512	&prev_indices,
4408f531	513	sizeof(u64),
fc8c72eb	514	next_read_location);
3e7ee490	515
454f18a9	516	/* Make sure all reads are done before we update the read index since */
4408f531 B	517	/* the writer may start writing to the read area once the read index */
4408f531 B	518	/is updated /
28b6ca9c	519	mb();
3e7ee490	520
454f18a9	521	/* Update the read index */
1ac58644	522	set_next_read_location(inring_info, next_read_location);
3e7ee490	523
fc8c72eb	524	/* Dumpring_info(Inring_info, "AFTER "); */
3e7ee490	525
fc8c72eb	526	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
3e7ee490 HJ	527
	528	return 0;
	529	}
	530
	531
	532	/*++
	533
	534	Name:
1ac58644	535	copyto_ringbuffer()
3e7ee490 HJ	536
	537	Description:
	538	Helper routine to copy from source to ring buffer.
	539	Assume there is enough room. Handles wrap-around in dest case only!!
	540
	541	--*/
bd1de709	542	static u32
1ac58644	543	copyto_ringbuffer(
fc8c72eb HZ	544	struct hv_ring_buffer_info *ring_info,
	545	u32 start_write_offset,
	546	void *src,
	547	u32 srclen)
3e7ee490	548	{
1ac58644 HZ	549	void *ring_buffer = get_ring_buffer(ring_info);
1ac58644 HZ	550	u32 ring_buffer_size = get_ring_buffersize(ring_info);
fc8c72eb	551	u32 frag_len;
3e7ee490	552
4408f531	553	/* wrap-around detected! */
fc8c72eb	554	if (srclen > ring_buffer_size - start_write_offset) {
fc8c72eb HZ	555	frag_len = ring_buffer_size - start_write_offset;
	556	memcpy(ring_buffer + start_write_offset, src, frag_len);
	557	memcpy(ring_buffer, src + frag_len, srclen - frag_len);
4408f531	558	} else
fc8c72eb	559	memcpy(ring_buffer + start_write_offset, src, srclen);
3e7ee490	560
fc8c72eb HZ	561	start_write_offset += srclen;
fc8c72eb HZ	562	start_write_offset %= ring_buffer_size;
3e7ee490	563
fc8c72eb	564	return start_write_offset;
3e7ee490 HJ	565	}
	566
	567
	568	/*++
	569
	570	Name:
1ac58644	571	copyfrom_ringbuffer()
3e7ee490 HJ	572
	573	Description:
	574	Helper routine to copy to source from ring buffer.
	575	Assume there is enough room. Handles wrap-around in src case only!!
	576
	577	--*/
bd1de709	578	static u32
1ac58644	579	copyfrom_ringbuffer(
fc8c72eb HZ	580	struct hv_ring_buffer_info *ring_info,
	581	void *dest,
	582	u32 destlen,
	583	u32 start_read_offset)
3e7ee490	584	{
1ac58644 HZ	585	void *ring_buffer = get_ring_buffer(ring_info);
1ac58644 HZ	586	u32 ring_buffer_size = get_ring_buffersize(ring_info);
3e7ee490	587
fc8c72eb	588	u32 frag_len;
3e7ee490	589
4408f531	590	/* wrap-around detected at the src */
fc8c72eb	591	if (destlen > ring_buffer_size - start_read_offset) {
fc8c72eb	592	frag_len = ring_buffer_size - start_read_offset;
3e7ee490	593
fc8c72eb HZ	594	memcpy(dest, ring_buffer + start_read_offset, frag_len);
fc8c72eb HZ	595	memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
4408f531 B	596	} else
4408f531 B	597
fc8c72eb	598	memcpy(dest, ring_buffer + start_read_offset, destlen);
4408f531	599
3e7ee490	600
fc8c72eb HZ	601	start_read_offset += destlen;
fc8c72eb HZ	602	start_read_offset %= ring_buffer_size;
3e7ee490	603
fc8c72eb	604	return start_read_offset;
3e7ee490 HJ	605	}
	606
	607
454f18a9	608	/* eof */