/drivers/staging/hv/ring_buffer.c
C | 524 lines | 259 code | 95 blank | 170 comment | 9 complexity | adeb173d48151d55779fcacbf9f0de2d MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
- /*
- *
- * 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 "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;
- /* 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_dump_ring_info()
- *
- * Dump out to console the ring buffer info
- *
- */
- void hv_dump_ring_info(struct hv_ring_buffer_info *ring_info, char *prefix)
- {
- u32 bytes_avail_towrite;
- u32 bytes_avail_toread;
- hv_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);
- }
- /*
- *
- * 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 -1;
- }
- /* 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 */
- mb();
- /* 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 -1;
- }
- /* 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 -1;
- }
- 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 */
- 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;
- }