Virtqueue Interface

Virtqueue Interface. More...

Data Structures
struct	virtq_desc
	virtqueue descriptor More...
struct	virtq_avail
	virtqueue available ring More...
struct	virtq_used_elem
	used descriptor chain More...
struct	virtq_used
	virtqueue used ring More...
struct	virtq_receive_callback_entry
	callback descriptor More...
struct	virtq
	virtqueue More...
struct	virtq_buf
	single buffer passed to virtq_add_buffer_chain More...

Macros
#define	VIRTQ_DESC_F_NEXT   1
	used in virtq_desc::flags, enables chaining descriptor via virtq_desc::next
#define	VIRTQ_DESC_F_WRITE   2
	used in virtq_desc::flags, makes descriptor device writeable

Typedefs
typedef void(*	virtq_receive_callback) (void *opaque, uint32_t used_len)
	receive callback function type

Functions
int	virtq_create (struct virtq *v, size_t size)
	creates virtqueue
void	virtq_free (struct virtq *v)
	frees virtqueue
int	virtq_add_buffer_chain (struct virtq *v, struct virtq_buf *bufs, uint16_t bufs_size, uint16_t device_readable_count, virtq_receive_callback cb, void *cb_opaque, k_timeout_t timeout)
	adds chain of buffers to the virtqueue
void	virtq_add_free_desc (struct virtq *v, uint16_t desc_idx)
	adds free descriptor back
int	virtq_get_free_desc (struct virtq *v, uint16_t *desc_idx, k_timeout_t timeout)
	gets next free descriptor

Detailed Description

Virtqueue Interface.

Macro Definition Documentation

VIRTQ_DESC_F_NEXT

#define VIRTQ_DESC_F_NEXT   1

#include <zephyr/drivers/virtio/virtqueue.h>

used in virtq_desc::flags, enables chaining descriptor via virtq_desc::next

VIRTQ_DESC_F_WRITE

#define VIRTQ_DESC_F_WRITE   2

#include <zephyr/drivers/virtio/virtqueue.h>

used in virtq_desc::flags, makes descriptor device writeable

Typedef Documentation

virtq_receive_callback

typedef void(* virtq_receive_callback) (void *opaque, uint32_t used_len)

#include <zephyr/drivers/virtio/virtqueue.h>

receive callback function type

Parameters

opaque	argument passed to the callback
used_len	total amount of bytes written to the descriptor chain by the virtio device

Function Documentation

virtq_add_buffer_chain()

int virtq_add_buffer_chain	(	struct virtq *	v,
		struct virtq_buf *	bufs,
		uint16_t	bufs_size,
		uint16_t	device_readable_count,
		virtq_receive_callback	cb,
		void *	cb_opaque,
		k_timeout_t	timeout )

#include <zephyr/drivers/virtio/virtqueue.h>

adds chain of buffers to the virtqueue

Note that according to spec 2.7.13.3 the device may access the buffers as soon as the avail->idx is increased, which is done at the end of this function, so the device may access the buffers without notifying it with virtio_notify_virtqueue

Parameters

v	virtqueue it operates on
bufs	array of buffers to be added to the virtqueue
bufs_size	amount of buffers
device_readable_count	amount of bufferes readable by the device, the first device_readable_count buffers will be set as device readable
cb	callback to be invoked after device returns the buffer chain, can be NULL
cb_opaque	opaque value that will be passed to the cb
timeout	amount of time it will wait for free descriptors, with K_NO_WAIT it can be called from isr

Returns

0 or error code on failure

virtq_add_free_desc()

void virtq_add_free_desc	(	struct virtq *	v,
		uint16_t	desc_idx )

#include <zephyr/drivers/virtio/virtqueue.h>

adds free descriptor back

Parameters

v	virtqueue it operates on
desc_idx	index of returned descriptor

virtq_create()

int virtq_create	(	struct virtq *	v,
		size_t	size )

#include <zephyr/drivers/virtio/virtqueue.h>

creates virtqueue

Parameters

v	virtqueue to be created
size	size of the virtqueue

Returns

0 or error code on failure

virtq_free()

void virtq_free

(

struct virtq *

v

)

#include <zephyr/drivers/virtio/virtqueue.h>

frees virtqueue

Parameters

v	virtqueue to be freed

virtq_get_free_desc()

int virtq_get_free_desc	(	struct virtq *	v,
		uint16_t *	desc_idx,
		k_timeout_t	timeout )

#include <zephyr/drivers/virtio/virtqueue.h>

gets next free descriptor

Parameters

v	virtqueue it operates on
desc_idx	address where index of descriptor will be stored
timeout	amount of time it will wait for free descriptor, with K_NO_WAIT it can be called from isr

Returns

0 or error code on failure