/*
*
* 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;
}
