[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 <[email protected]>
 *   Hank Janssen  <[email protected]>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 <[email protected]>
	20	* Hank Janssen <[email protected]>
	21	*
	22	*/
0a46618d	23	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3e7ee490	24
a0086dc5 GKH	25	#include <linux/kernel.h>
a0086dc5 GKH	26	#include <linux/mm.h>
645954c5	27	#include "logging.h"
8f078ca6	28	#include "ring_buffer.h"
3e7ee490	29
3e7ee490	30
454f18a9 BP	31	/* #defines */
	32
	33
	34	/* Amount of space to write to */
0686e4f4	35	#define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r)) ? ((z) - ((w) - (r))) : ((r) - (w))
3e7ee490 HJ	36
	37
	38	/*++
	39
	40	Name:
1ac58644	41	get_ringbuffer_availbytes()
3e7ee490 HJ	42
	43	Description:
	44	Get number of bytes available to read and to write to
	45	for the specified ring buffer
	46
	47	--*/
	48	static inline void
1ac58644 HZ	49	get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
1ac58644 HZ	50	u32 read, u32 write)
3e7ee490	51	{
4408f531	52	u32 read_loc, write_loc;
3e7ee490	53
454f18a9	54	/* Capture the read/write indices before they changed */
82f8bd40 HZ	55	read_loc = rbi->ring_buffer->read_index;
82f8bd40 HZ	56	write_loc = rbi->ring_buffer->write_index;
3e7ee490	57
82f8bd40 HZ	58	*write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->ring_datasize);
82f8bd40 HZ	59	read = rbi->ring_datasize - write;
3e7ee490 HJ	60	}
	61
	62	/*++
	63
	64	Name:
1ac58644	65	get_next_write_location()
3e7ee490 HJ	66
	67	Description:
	68	Get the next write location for the specified ring buffer
	69
	70	--*/
4d643114	71	static inline u32
1ac58644	72	get_next_write_location(struct hv_ring_buffer_info *ring_info)
3e7ee490	73	{
fc8c72eb	74	u32 next = ring_info->ring_buffer->write_index;
3e7ee490	75
fc8c72eb	76	/* ASSERT(next < ring_info->RingDataSize); */
3e7ee490 HJ	77
	78	return next;
	79	}
	80
	81	/*++
	82
	83	Name:
1ac58644	84	set_next_write_location()
3e7ee490 HJ	85
	86	Description:
	87	Set the next write location for the specified ring buffer
	88
	89	--*/
	90	static inline void
1ac58644	91	set_next_write_location(struct hv_ring_buffer_info *ring_info,
fc8c72eb	92	u32 next_write_location)
3e7ee490	93	{
fc8c72eb	94	ring_info->ring_buffer->write_index = next_write_location;
3e7ee490 HJ	95	}
	96
	97	/*++
	98
	99	Name:
1ac58644	100	get_next_read_location()
3e7ee490 HJ	101
	102	Description:
	103	Get the next read location for the specified ring buffer
	104
	105	--*/
4d643114	106	static inline u32
1ac58644	107	get_next_read_location(struct hv_ring_buffer_info *ring_info)
3e7ee490	108	{
fc8c72eb	109	u32 next = ring_info->ring_buffer->read_index;
3e7ee490	110
fc8c72eb	111	/* ASSERT(next < ring_info->RingDataSize); */
3e7ee490 HJ	112
	113	return next;
	114	}
	115
	116	/*++
	117
	118	Name:
1ac58644	119	get_next_readlocation_withoffset()
3e7ee490 HJ	120
	121	Description:
	122	Get the next read location + offset for the specified ring buffer.
	123	This allows the caller to skip
	124
	125	--*/
4d643114	126	static inline u32
1ac58644 HZ	127	get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
1ac58644 HZ	128	u32 offset)
3e7ee490	129	{
fc8c72eb	130	u32 next = ring_info->ring_buffer->read_index;
3e7ee490	131
fc8c72eb HZ	132	/* ASSERT(next < ring_info->RingDataSize); */
	133	next += offset;
	134	next %= ring_info->ring_datasize;
3e7ee490 HJ	135
	136	return next;
	137	}
	138
	139	/*++
	140
	141	Name:
1ac58644	142	set_next_read_location()
3e7ee490 HJ	143
	144	Description:
	145	Set the next read location for the specified ring buffer
	146
	147	--*/
	148	static inline void
1ac58644	149	set_next_read_location(struct hv_ring_buffer_info *ring_info,
fc8c72eb	150	u32 next_read_location)
3e7ee490	151	{
fc8c72eb	152	ring_info->ring_buffer->read_index = next_read_location;
3e7ee490 HJ	153	}
	154
	155
	156	/*++
	157
	158	Name:
1ac58644	159	get_ring_buffer()
3e7ee490 HJ	160
	161	Description:
	162	Get the start of the ring buffer
	163
	164	--*/
8282c400	165	static inline void *
1ac58644	166	get_ring_buffer(struct hv_ring_buffer_info *ring_info)
3e7ee490	167	{
fc8c72eb	168	return (void *)ring_info->ring_buffer->buffer;
3e7ee490 HJ	169	}
	170
	171
	172	/*++
	173
	174	Name:
1ac58644	175	get_ring_buffersize()
3e7ee490 HJ	176
	177	Description:
	178	Get the size of the ring buffer
	179
	180	--*/
4d643114	181	static inline u32
1ac58644	182	get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
3e7ee490	183	{
fc8c72eb	184	return ring_info->ring_datasize;
3e7ee490 HJ	185	}
	186
	187	/*++
	188
	189	Name:
1ac58644	190	get_ring_bufferindices()
3e7ee490 HJ	191
3e7ee490 HJ	192	Description:
59471438	193	Get the read and write indices as u64 of the specified ring buffer
3e7ee490 HJ	194
3e7ee490 HJ	195	--*/
59471438	196	static inline u64
1ac58644	197	get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
3e7ee490	198	{
fc8c72eb	199	return (u64)ring_info->ring_buffer->write_index << 32;
3e7ee490 HJ	200	}
	201
	202
	203	/*++
	204
	205	Name:
1ac58644	206	dump_ring_info()
3e7ee490 HJ	207
	208	Description:
	209	Dump out to console the ring buffer info
	210
	211	--*/
1ac58644	212	void dump_ring_info(struct hv_ring_buffer_info ring_info, char prefix)
3e7ee490	213	{
fc8c72eb HZ	214	u32 bytes_avail_towrite;
fc8c72eb HZ	215	u32 bytes_avail_toread;
3e7ee490	216
1ac58644	217	get_ringbuffer_availbytes(ring_info,
fc8c72eb HZ	218	&bytes_avail_toread,
fc8c72eb HZ	219	&bytes_avail_towrite);
3e7ee490	220
4408f531 B	221	DPRINT(VMBUS,
	222	DEBUG_RING_LVL,
	223	"%s <<ringinfo %p buffer %p avail write %u "
	224	"avail read %u read idx %u write idx %u>>",
fc8c72eb HZ	225	prefix,
	226	ring_info,
	227	ring_info->ring_buffer->buffer,
	228	bytes_avail_towrite,
	229	bytes_avail_toread,
	230	ring_info->ring_buffer->read_index,
	231	ring_info->ring_buffer->write_index);
3e7ee490 HJ	232	}
3e7ee490 HJ	233
454f18a9 BP	234
	235	/* Internal routines */
	236
4d643114	237	static u32
1ac58644	238	copyto_ringbuffer(
fc8c72eb HZ	239	struct hv_ring_buffer_info *ring_info,
	240	u32 start_write_offset,
	241	void *src,
	242	u32 srclen);
3e7ee490	243
4d643114	244	static u32
1ac58644	245	copyfrom_ringbuffer(
fc8c72eb HZ	246	struct hv_ring_buffer_info *ring_info,
	247	void *dest,
	248	u32 destlen,
	249	u32 start_read_offset);
3e7ee490 HJ	250
	251
	252
	253	/*++
	254
	255	Name:
1ac58644	256	ringbuffer_get_debuginfo()
3e7ee490 HJ	257
	258	Description:
	259	Get various debug metrics for the specified ring buffer
	260
	261	--*/
1ac58644	262	void ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
80682b7a	263	struct hv_ring_buffer_debug_info *debug_info)
3e7ee490	264	{
fc8c72eb HZ	265	u32 bytes_avail_towrite;
fc8c72eb HZ	266	u32 bytes_avail_toread;
3e7ee490	267
fc8c72eb	268	if (ring_info->ring_buffer) {
1ac58644	269	get_ringbuffer_availbytes(ring_info,
fc8c72eb HZ	270	&bytes_avail_toread,
fc8c72eb HZ	271	&bytes_avail_towrite);
3e7ee490	272
fc8c72eb HZ	273	debug_info->bytes_avail_toread = bytes_avail_toread;
fc8c72eb HZ	274	debug_info->bytes_avail_towrite = bytes_avail_towrite;
82f8bd40	275	debug_info->current_read_index =
fc8c72eb	276	ring_info->ring_buffer->read_index;
82f8bd40	277	debug_info->current_write_index =
fc8c72eb	278	ring_info->ring_buffer->write_index;
82f8bd40	279	debug_info->current_interrupt_mask =
fc8c72eb	280	ring_info->ring_buffer->interrupt_mask;
3e7ee490 HJ	281	}
	282	}
	283
	284
	285	/*++
	286
	287	Name:
1ac58644	288	get_ringbuffer_interrupt_mask()
3e7ee490 HJ	289
	290	Description:
	291	Get the interrupt mask for the specified ring buffer
	292
	293	--*/
1ac58644	294	u32 get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *rbi)
3e7ee490	295	{
82f8bd40	296	return rbi->ring_buffer->interrupt_mask;
3e7ee490 HJ	297	}
	298
	299	/*++
	300
	301	Name:
1ac58644	302	ringbuffer_init()
3e7ee490 HJ	303
	304	Description:
	305	Initialize the ring buffer
	306
	307	--*/
1ac58644	308	int ringbuffer_init(struct hv_ring_buffer_info *ring_info,
fc8c72eb	309	void *buffer, u32 buflen)
3e7ee490	310	{
4a1b3acc	311	if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
3324fb40	312	return -EINVAL;
3e7ee490	313
fc8c72eb	314	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
3e7ee490	315
fc8c72eb HZ	316	ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
	317	ring_info->ring_buffer->read_index =
	318	ring_info->ring_buffer->write_index = 0;
3e7ee490	319
fc8c72eb HZ	320	ring_info->ring_size = buflen;
fc8c72eb HZ	321	ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
3e7ee490	322
fc8c72eb	323	spin_lock_init(&ring_info->ring_lock);
3e7ee490 HJ	324
	325	return 0;
	326	}
	327
	328	/*++
	329
	330	Name:
1ac58644	331	ringbuffer_cleanup()
3e7ee490 HJ	332
	333	Description:
	334	Cleanup the ring buffer
	335
	336	--*/
1ac58644	337	void ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
3e7ee490	338	{
3e7ee490 HJ	339	}
	340
	341	/*++
	342
	343	Name:
1ac58644	344	ringbuffer_write()
3e7ee490 HJ	345
	346	Description:
	347	Write to the ring buffer
	348
	349	--*/
1ac58644	350	int ringbuffer_write(struct hv_ring_buffer_info *outring_info,
3523a805	351	struct scatterlist *sglist, u32 sgcount)
3e7ee490	352	{
4408f531	353	int i = 0;
fc8c72eb HZ	354	u32 bytes_avail_towrite;
	355	u32 bytes_avail_toread;
	356	u32 totalbytes_towrite = 0;
3e7ee490	357
b219b3f7	358	struct scatterlist *sg;
fc8c72eb HZ	359	volatile u32 next_write_location;
fc8c72eb HZ	360	u64 prev_indices = 0;
a98f96ee	361	unsigned long flags;
3e7ee490	362
b219b3f7	363	for_each_sg(sglist, sg, sgcount, i)
3e7ee490	364	{
fc8c72eb	365	totalbytes_towrite += sg->length;
3e7ee490 HJ	366	}
3e7ee490 HJ	367
fc8c72eb	368	totalbytes_towrite += sizeof(u64);
3e7ee490	369
fc8c72eb	370	spin_lock_irqsave(&outring_info->ring_lock, flags);
3e7ee490	371
1ac58644	372	get_ringbuffer_availbytes(outring_info,
fc8c72eb HZ	373	&bytes_avail_toread,
fc8c72eb HZ	374	&bytes_avail_towrite);
3e7ee490	375
fc8c72eb	376	/* Dumpring_info(Outring_info, "BEFORE "); */
3e7ee490	377
4408f531 B	378	/* If there is only room for the packet, assume it is full. */
4408f531 B	379	/* Otherwise, the next time around, we think the ring buffer */
454f18a9	380	/* is empty since the read index == write index */
fc8c72eb	381	if (bytes_avail_towrite <= totalbytes_towrite) {
fc8c72eb	382	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
3e7ee490 HJ	383	return -1;
	384	}
	385
454f18a9	386	/* Write to the ring buffer */
1ac58644	387	next_write_location = get_next_write_location(outring_info);
3e7ee490	388
b219b3f7	389	for_each_sg(sglist, sg, sgcount, i)
3e7ee490	390	{
1ac58644	391	next_write_location = copyto_ringbuffer(outring_info,
fc8c72eb	392	next_write_location,
b219b3f7 NP	393	sg_virt(sg),
b219b3f7 NP	394	sg->length);
3e7ee490 HJ	395	}
3e7ee490 HJ	396
454f18a9	397	/* Set previous packet start */
1ac58644	398	prev_indices = get_ring_bufferindices(outring_info);
3e7ee490	399
1ac58644	400	next_write_location = copyto_ringbuffer(outring_info,
fc8c72eb HZ	401	next_write_location,
fc8c72eb HZ	402	&prev_indices,
b219b3f7	403	sizeof(u64));
3e7ee490	404
454f18a9	405	/* Make sure we flush all writes before updating the writeIndex */
28b6ca9c	406	mb();
3e7ee490	407
454f18a9	408	/* Now, update the write location */
1ac58644	409	set_next_write_location(outring_info, next_write_location);
3e7ee490	410
fc8c72eb	411	/* Dumpring_info(Outring_info, "AFTER "); */
3e7ee490	412
fc8c72eb	413	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
3e7ee490 HJ	414	return 0;
	415	}
	416
	417
	418	/*++
	419
	420	Name:
1ac58644	421	ringbuffer_peek()
3e7ee490 HJ	422
	423	Description:
	424	Read without advancing the read index
	425
	426	--*/
1ac58644	427	int ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
fc8c72eb	428	void *Buffer, u32 buflen)
3e7ee490	429	{
fc8c72eb HZ	430	u32 bytes_avail_towrite;
	431	u32 bytes_avail_toread;
	432	u32 next_read_location = 0;
a98f96ee	433	unsigned long flags;
3e7ee490	434
fc8c72eb	435	spin_lock_irqsave(&Inring_info->ring_lock, flags);
3e7ee490	436
1ac58644	437	get_ringbuffer_availbytes(Inring_info,
fc8c72eb HZ	438	&bytes_avail_toread,
fc8c72eb HZ	439	&bytes_avail_towrite);
3e7ee490	440
454f18a9	441	/* Make sure there is something to read */
fc8c72eb	442	if (bytes_avail_toread < buflen) {
4408f531 B	443	/* DPRINT_DBG(VMBUS,
	444	"got callback but not enough to read "
	445	"<avail to read %d read size %d>!!",
fc8c72eb	446	bytes_avail_toread,
4408f531	447	BufferLen); */
3e7ee490	448
fc8c72eb	449	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
3e7ee490 HJ	450
	451	return -1;
	452	}
	453
454f18a9	454	/* Convert to byte offset */
1ac58644	455	next_read_location = get_next_read_location(Inring_info);
3e7ee490	456
1ac58644	457	next_read_location = copyfrom_ringbuffer(Inring_info,
4408f531	458	Buffer,
fc8c72eb HZ	459	buflen,
fc8c72eb HZ	460	next_read_location);
3e7ee490	461
fc8c72eb	462	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
3e7ee490 HJ	463
	464	return 0;
	465	}
	466
	467
	468	/*++
	469
	470	Name:
1ac58644	471	ringbuffer_read()
3e7ee490 HJ	472
	473	Description:
	474	Read and advance the read index
	475
	476	--*/
1ac58644	477	int ringbuffer_read(struct hv_ring_buffer_info inring_info, void buffer,
fc8c72eb	478	u32 buflen, u32 offset)
3e7ee490	479	{
fc8c72eb HZ	480	u32 bytes_avail_towrite;
	481	u32 bytes_avail_toread;
	482	u32 next_read_location = 0;
	483	u64 prev_indices = 0;
a98f96ee	484	unsigned long flags;
3e7ee490	485
fc8c72eb	486	if (buflen <= 0)
a16e1485	487	return -EINVAL;
3e7ee490	488
fc8c72eb	489	spin_lock_irqsave(&inring_info->ring_lock, flags);
3e7ee490	490
1ac58644	491	get_ringbuffer_availbytes(inring_info,
fc8c72eb HZ	492	&bytes_avail_toread,
fc8c72eb HZ	493	&bytes_avail_towrite);
3e7ee490	494
fc8c72eb	495	/* Dumpring_info(Inring_info, "BEFORE "); */
3e7ee490	496
454f18a9	497	/* Make sure there is something to read */
fc8c72eb	498	if (bytes_avail_toread < buflen) {
fc8c72eb	499	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
3e7ee490 HJ	500
	501	return -1;
	502	}
	503
1ac58644 HZ	504	next_read_location =
1ac58644 HZ	505	get_next_readlocation_withoffset(inring_info, offset);
3e7ee490	506
1ac58644	507	next_read_location = copyfrom_ringbuffer(inring_info,
fc8c72eb HZ	508	buffer,
	509	buflen,
	510	next_read_location);
3e7ee490	511
1ac58644	512	next_read_location = copyfrom_ringbuffer(inring_info,
fc8c72eb	513	&prev_indices,
4408f531	514	sizeof(u64),
fc8c72eb	515	next_read_location);
3e7ee490	516
454f18a9	517	/* Make sure all reads are done before we update the read index since */
4408f531 B	518	/* the writer may start writing to the read area once the read index */
4408f531 B	519	/is updated /
28b6ca9c	520	mb();
3e7ee490	521
454f18a9	522	/* Update the read index */
1ac58644	523	set_next_read_location(inring_info, next_read_location);
3e7ee490	524
fc8c72eb	525	/* Dumpring_info(Inring_info, "AFTER "); */
3e7ee490	526
fc8c72eb	527	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
3e7ee490 HJ	528
	529	return 0;
	530	}
	531
	532
	533	/*++
	534
	535	Name:
1ac58644	536	copyto_ringbuffer()
3e7ee490 HJ	537
	538	Description:
	539	Helper routine to copy from source to ring buffer.
	540	Assume there is enough room. Handles wrap-around in dest case only!!
	541
	542	--*/
bd1de709	543	static u32
1ac58644	544	copyto_ringbuffer(
fc8c72eb HZ	545	struct hv_ring_buffer_info *ring_info,
	546	u32 start_write_offset,
	547	void *src,
	548	u32 srclen)
3e7ee490	549	{
1ac58644 HZ	550	void *ring_buffer = get_ring_buffer(ring_info);
1ac58644 HZ	551	u32 ring_buffer_size = get_ring_buffersize(ring_info);
fc8c72eb	552	u32 frag_len;
3e7ee490	553
4408f531	554	/* wrap-around detected! */
fc8c72eb	555	if (srclen > ring_buffer_size - start_write_offset) {
fc8c72eb HZ	556	frag_len = ring_buffer_size - start_write_offset;
	557	memcpy(ring_buffer + start_write_offset, src, frag_len);
	558	memcpy(ring_buffer, src + frag_len, srclen - frag_len);
4408f531	559	} else
fc8c72eb	560	memcpy(ring_buffer + start_write_offset, src, srclen);
3e7ee490	561
fc8c72eb HZ	562	start_write_offset += srclen;
fc8c72eb HZ	563	start_write_offset %= ring_buffer_size;
3e7ee490	564
fc8c72eb	565	return start_write_offset;
3e7ee490 HJ	566	}
	567
	568
	569	/*++
	570
	571	Name:
1ac58644	572	copyfrom_ringbuffer()
3e7ee490 HJ	573
	574	Description:
	575	Helper routine to copy to source from ring buffer.
	576	Assume there is enough room. Handles wrap-around in src case only!!
	577
	578	--*/
bd1de709	579	static u32
1ac58644	580	copyfrom_ringbuffer(
fc8c72eb HZ	581	struct hv_ring_buffer_info *ring_info,
	582	void *dest,
	583	u32 destlen,
	584	u32 start_read_offset)
3e7ee490	585	{
1ac58644 HZ	586	void *ring_buffer = get_ring_buffer(ring_info);
1ac58644 HZ	587	u32 ring_buffer_size = get_ring_buffersize(ring_info);
3e7ee490	588
fc8c72eb	589	u32 frag_len;
3e7ee490	590
4408f531	591	/* wrap-around detected at the src */
fc8c72eb	592	if (destlen > ring_buffer_size - start_read_offset) {
fc8c72eb	593	frag_len = ring_buffer_size - start_read_offset;
3e7ee490	594
fc8c72eb HZ	595	memcpy(dest, ring_buffer + start_read_offset, frag_len);
fc8c72eb HZ	596	memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
4408f531 B	597	} else
4408f531 B	598
fc8c72eb	599	memcpy(dest, ring_buffer + start_read_offset, destlen);
4408f531	600
3e7ee490	601
fc8c72eb HZ	602	start_read_offset += destlen;
fc8c72eb HZ	603	start_read_offset %= ring_buffer_size;
3e7ee490	604
fc8c72eb	605	return start_read_offset;
3e7ee490 HJ	606	}
	607
	608
454f18a9	609	/* eof */