466 lines
10 KiB
C
466 lines
10 KiB
C
/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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*
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* Authors:
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* Haiyang Zhang <haiyangz@microsoft.com>
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* Hank Janssen <hjanssen@microsoft.com>
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* K. Y. Srinivasan <kys@microsoft.com>
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hyperv.h>
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#include "hyperv_vmbus.h"
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/*
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* hv_get_next_write_location()
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*
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* Get the next write location for the specified ring buffer
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*
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*/
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static inline u32
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hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
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{
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u32 next = ring_info->ring_buffer->write_index;
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return next;
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}
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/*
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* hv_set_next_write_location()
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*
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* Set the next write location for the specified ring buffer
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*
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*/
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static inline void
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hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
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u32 next_write_location)
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{
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ring_info->ring_buffer->write_index = next_write_location;
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}
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/*
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* hv_get_next_read_location()
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*
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* Get the next read location for the specified ring buffer
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*/
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static inline u32
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hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
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{
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u32 next = ring_info->ring_buffer->read_index;
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return next;
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}
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/*
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* hv_get_next_readlocation_withoffset()
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*
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* Get the next read location + offset for the specified ring buffer.
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* This allows the caller to skip
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*/
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static inline u32
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hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
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u32 offset)
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{
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u32 next = ring_info->ring_buffer->read_index;
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next += offset;
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next %= ring_info->ring_datasize;
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return next;
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}
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/*
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*
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* hv_set_next_read_location()
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*
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* Set the next read location for the specified ring buffer
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*
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*/
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static inline void
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hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
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u32 next_read_location)
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{
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ring_info->ring_buffer->read_index = next_read_location;
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}
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/*
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*
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* hv_get_ring_buffer()
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*
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* Get the start of the ring buffer
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*/
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static inline void *
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hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
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{
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return (void *)ring_info->ring_buffer->buffer;
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}
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/*
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*
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* hv_get_ring_buffersize()
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*
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* Get the size of the ring buffer
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*/
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static inline u32
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hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
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{
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return ring_info->ring_datasize;
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}
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/*
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*
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* hv_get_ring_bufferindices()
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*
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* Get the read and write indices as u64 of the specified ring buffer
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*
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*/
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static inline u64
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hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
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{
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return (u64)ring_info->ring_buffer->write_index << 32;
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}
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/*
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*
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* hv_copyfrom_ringbuffer()
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*
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* Helper routine to copy to source from ring buffer.
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* Assume there is enough room. Handles wrap-around in src case only!!
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*
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*/
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static u32 hv_copyfrom_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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void *dest,
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u32 destlen,
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u32 start_read_offset)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected at the src */
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if (destlen > ring_buffer_size - start_read_offset) {
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frag_len = ring_buffer_size - start_read_offset;
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memcpy(dest, ring_buffer + start_read_offset, frag_len);
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memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
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} else
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memcpy(dest, ring_buffer + start_read_offset, destlen);
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start_read_offset += destlen;
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start_read_offset %= ring_buffer_size;
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return start_read_offset;
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}
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/*
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*
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* hv_copyto_ringbuffer()
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*
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* Helper routine to copy from source to ring buffer.
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* Assume there is enough room. Handles wrap-around in dest case only!!
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*
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*/
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static u32 hv_copyto_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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u32 start_write_offset,
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void *src,
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u32 srclen)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected! */
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if (srclen > ring_buffer_size - start_write_offset) {
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frag_len = ring_buffer_size - start_write_offset;
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memcpy(ring_buffer + start_write_offset, src, frag_len);
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memcpy(ring_buffer, src + frag_len, srclen - frag_len);
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} else
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memcpy(ring_buffer + start_write_offset, src, srclen);
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start_write_offset += srclen;
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start_write_offset %= ring_buffer_size;
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return start_write_offset;
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}
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/*
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*
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* hv_ringbuffer_get_debuginfo()
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*
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* Get various debug metrics for the specified ring buffer
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*
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*/
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void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
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struct hv_ring_buffer_debug_info *debug_info)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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if (ring_info->ring_buffer) {
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hv_get_ringbuffer_availbytes(ring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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debug_info->bytes_avail_toread = bytes_avail_toread;
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debug_info->bytes_avail_towrite = bytes_avail_towrite;
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debug_info->current_read_index =
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ring_info->ring_buffer->read_index;
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debug_info->current_write_index =
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ring_info->ring_buffer->write_index;
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debug_info->current_interrupt_mask =
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ring_info->ring_buffer->interrupt_mask;
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}
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}
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/*
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*
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* hv_get_ringbuffer_interrupt_mask()
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*
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* Get the interrupt mask for the specified ring buffer
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*
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*/
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u32 hv_get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *rbi)
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{
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return rbi->ring_buffer->interrupt_mask;
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}
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/*
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*
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* hv_ringbuffer_init()
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*
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*Initialize the ring buffer
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*
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*/
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int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
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void *buffer, u32 buflen)
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{
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if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
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return -EINVAL;
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memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
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ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
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ring_info->ring_buffer->read_index =
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ring_info->ring_buffer->write_index = 0;
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ring_info->ring_size = buflen;
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ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
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spin_lock_init(&ring_info->ring_lock);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_cleanup()
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*
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* Cleanup the ring buffer
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*
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*/
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void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
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{
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}
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/*
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*
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* hv_ringbuffer_write()
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*
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* Write to the ring buffer
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*
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*/
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int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
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struct scatterlist *sglist, u32 sgcount)
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{
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int i = 0;
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 totalbytes_towrite = 0;
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struct scatterlist *sg;
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u32 next_write_location;
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u64 prev_indices = 0;
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unsigned long flags;
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for_each_sg(sglist, sg, sgcount, i)
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{
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totalbytes_towrite += sg->length;
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}
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totalbytes_towrite += sizeof(u64);
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spin_lock_irqsave(&outring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(outring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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/* If there is only room for the packet, assume it is full. */
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/* Otherwise, the next time around, we think the ring buffer */
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/* is empty since the read index == write index */
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if (bytes_avail_towrite <= totalbytes_towrite) {
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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return -EAGAIN;
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}
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/* Write to the ring buffer */
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next_write_location = hv_get_next_write_location(outring_info);
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for_each_sg(sglist, sg, sgcount, i)
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{
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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sg_virt(sg),
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sg->length);
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}
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/* Set previous packet start */
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prev_indices = hv_get_ring_bufferindices(outring_info);
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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&prev_indices,
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sizeof(u64));
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/* Make sure we flush all writes before updating the writeIndex */
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smp_wmb();
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/* Now, update the write location */
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hv_set_next_write_location(outring_info, next_write_location);
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_peek()
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*
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* Read without advancing the read index
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*
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*/
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int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
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void *Buffer, u32 buflen)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 next_read_location = 0;
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unsigned long flags;
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spin_lock_irqsave(&Inring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(Inring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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/* Make sure there is something to read */
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if (bytes_avail_toread < buflen) {
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spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
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return -EAGAIN;
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}
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/* Convert to byte offset */
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next_read_location = hv_get_next_read_location(Inring_info);
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next_read_location = hv_copyfrom_ringbuffer(Inring_info,
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Buffer,
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buflen,
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next_read_location);
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spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_read()
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*
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* Read and advance the read index
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*
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*/
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int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
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u32 buflen, u32 offset)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 next_read_location = 0;
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u64 prev_indices = 0;
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unsigned long flags;
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if (buflen <= 0)
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return -EINVAL;
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spin_lock_irqsave(&inring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(inring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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/* Make sure there is something to read */
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if (bytes_avail_toread < buflen) {
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spin_unlock_irqrestore(&inring_info->ring_lock, flags);
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return -EAGAIN;
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}
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next_read_location =
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hv_get_next_readlocation_withoffset(inring_info, offset);
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next_read_location = hv_copyfrom_ringbuffer(inring_info,
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buffer,
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buflen,
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next_read_location);
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next_read_location = hv_copyfrom_ringbuffer(inring_info,
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&prev_indices,
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sizeof(u64),
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next_read_location);
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/* Make sure all reads are done before we update the read index since */
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/* the writer may start writing to the read area once the read index */
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/*is updated */
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smp_mb();
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/* Update the read index */
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hv_set_next_read_location(inring_info, next_read_location);
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spin_unlock_irqrestore(&inring_info->ring_lock, flags);
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return 0;
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}
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