/* * * 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 voidhv_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 u32hv_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 voidhv_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 u32hv_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 u32hv_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 voidhv_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 u32hv_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 u64hv_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;}