diff options
Diffstat (limited to 'drivers/hv/ring_buffer.c')
| -rw-r--r-- | drivers/hv/ring_buffer.c | 496 |
1 files changed, 496 insertions, 0 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c new file mode 100644 index 0000000..8af25a0 --- /dev/null +++ b/drivers/hv/ring_buffer.c @@ -0,0 +1,496 @@ +/* + * + * 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; +} |
