309 lines
11 KiB
C
309 lines
11 KiB
C
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#ifndef _LINUX_VIRTIO_H
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#define _LINUX_VIRTIO_H
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/* Everything a virtio driver needs to work with any particular virtio
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* implementation. */
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#include <linux/types.h>
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#include <linux/scatterlist.h>
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#include <linux/spinlock.h>
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#include <linux/device.h>
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#include <linux/mod_devicetable.h>
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#include <linux/gfp.h>
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/**
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* virtqueue - a queue to register buffers for sending or receiving.
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* @list: the chain of virtqueues for this device
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* @callback: the function to call when buffers are consumed (can be NULL).
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* @name: the name of this virtqueue (mainly for debugging)
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* @vdev: the virtio device this queue was created for.
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* @vq_ops: the operations for this virtqueue (see below).
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* @priv: a pointer for the virtqueue implementation to use.
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*/
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struct virtqueue {
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struct list_head list;
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void (*callback)(struct virtqueue *vq);
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const char *name;
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struct virtio_device *vdev;
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struct virtqueue_ops *vq_ops;
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void *priv;
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};
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/**
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* virtqueue_ops - operations for virtqueue abstraction layer
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* @add_buf: expose buffer to other end
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* vq: the struct virtqueue we're talking about.
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* sg: the description of the buffer(s).
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* out_num: the number of sg readable by other side
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* in_num: the number of sg which are writable (after readable ones)
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* data: the token identifying the buffer.
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* Returns remaining capacity of queue (sg segments) or a negative error.
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* @kick: update after add_buf
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* vq: the struct virtqueue
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* After one or more add_buf calls, invoke this to kick the other side.
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* @get_buf: get the next used buffer
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* vq: the struct virtqueue we're talking about.
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* len: the length written into the buffer
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* Returns NULL or the "data" token handed to add_buf.
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* @disable_cb: disable callbacks
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* vq: the struct virtqueue we're talking about.
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* Note that this is not necessarily synchronous, hence unreliable and only
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* useful as an optimization.
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* @enable_cb: restart callbacks after disable_cb.
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* vq: the struct virtqueue we're talking about.
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* This re-enables callbacks; it returns "false" if there are pending
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* buffers in the queue, to detect a possible race between the driver
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* checking for more work, and enabling callbacks.
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* @enable_cb_delayed: restart callbacks after disable_cb.
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* vq: the struct virtqueue we're talking about.
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* This re-enables callbacks but hints to the other side to delay
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* interrupts until most of the available buffers have been processed;
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* it returns "false" if there are many pending buffers in the queue,
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* to detect a possible race between the driver checking for more work,
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* and enabling callbacks.
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* Caller must ensure we don't call this with other virtqueue
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* operations at the same time (except where noted).
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* @detach_unused_buf: detach first unused buffer
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* vq: the struct virtqueue we're talking about.
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* Returns NULL or the "data" token handed to add_buf
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* @get_impl_size: return the size of the virtqueue's implementation
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* vq: the struct virtqueue containing the implementation of interest.
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* Returns the size of the implementation. This is mainly used for
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* boasting to userspace. Unlike other operations, this need not
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* be serialized.
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*
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* Locking rules are straightforward: the driver is responsible for
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* locking. No two operations may be invoked simultaneously, with the exception
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* of @disable_cb.
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*
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* All operations can be called in any context.
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*/
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struct virtqueue_ops {
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int (*add_buf)(struct virtqueue *vq,
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struct scatterlist sg[],
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unsigned int out_num,
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unsigned int in_num,
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void *data,
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gfp_t gfp);
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void (*kick)(struct virtqueue *vq);
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bool (*kick_prepare)(struct virtqueue *vq);
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void (*kick_notify)(struct virtqueue *vq);
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void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
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void (*disable_cb)(struct virtqueue *vq);
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bool (*enable_cb)(struct virtqueue *vq);
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bool (*enable_cb_delayed)(struct virtqueue *vq);
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void *(*detach_unused_buf)(struct virtqueue *vq);
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unsigned int (*get_impl_size)(struct virtqueue *vq);
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};
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/**
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* virtqueue_add_buf - expose buffer to other end
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* @vq: the struct virtqueue we're talking about.
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* @sg: the description of the buffer(s).
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* @out_num: the number of sg readable by other side
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* @in_num: the number of sg which are writable (after readable ones)
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* @data: the token identifying the buffer.
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* @gfp: how to do memory allocations (if necessary).
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*
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* Caller must ensure we don't call this with other virtqueue operations
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* at the same time (except where noted).
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*
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* Returns remaining capacity of queue or a negative error.
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*/
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static inline int virtqueue_add_buf(struct virtqueue *vq,
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struct scatterlist sg[],
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unsigned int out_num,
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unsigned int in_num,
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void *data,
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gfp_t gfp)
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{
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return vq->vq_ops->add_buf(vq, sg, out_num, in_num, data, gfp);
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}
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/**
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* virtqueue_kick - update after add_buf
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* @vq: the struct virtqueue
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*
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* After one or more virtqueue_add_buf calls, invoke this to kick
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* the other side.
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*
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* Caller must ensure we don't call this with other virtqueue
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* operations at the same time (except where noted).
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*/
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static inline void virtqueue_kick(struct virtqueue *vq)
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{
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vq->vq_ops->kick(vq);
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}
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/**
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* virtqueue_kick_prepare - first half of split virtqueue_kick call.
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* @vq: the struct virtqueue
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*
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* Instead of virtqueue_kick(), you can do:
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* if (virtqueue_kick_prepare(vq))
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* virtqueue_kick_notify(vq);
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*
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* This is sometimes useful because the virtqueue_kick_prepare() needs
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* to be serialized, but the actual virtqueue_kick_notify() call does not.
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*/
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static inline bool virtqueue_kick_prepare(struct virtqueue *vq)
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{
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return vq->vq_ops->kick_prepare(vq);
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}
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/**
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* virtqueue_kick_notify - second half of split virtqueue_kick call.
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* @vq: the struct virtqueue
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*/
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static inline void virtqueue_kick_notify(struct virtqueue *vq)
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{
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vq->vq_ops->kick_notify(vq);
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}
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/**
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* virtqueue_get_buf - get the next used buffer
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* @vq: the struct virtqueue we're talking about.
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* @len: the length written into the buffer
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*
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* If the driver wrote data into the buffer, @len will be set to the
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* amount written. This means you don't need to clear the buffer
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* beforehand to ensure there's no data leakage in the case of short
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* writes.
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*
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* Caller must ensure we don't call this with other virtqueue
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* operations at the same time (except where noted).
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*
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* Returns NULL if there are no used buffers, or the "data" token
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* handed to virtqueue_add_buf().
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*/
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static inline void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
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{
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return vq->vq_ops->get_buf(vq, len);
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}
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/**
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* virtqueue_disable_cb - disable callbacks
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* @vq: the struct virtqueue we're talking about.
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*
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* Note that this is not necessarily synchronous, hence unreliable and only
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* useful as an optimization.
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*
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* Unlike other operations, this need not be serialized.
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*/
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static inline void virtqueue_disable_cb(struct virtqueue *vq)
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{
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vq->vq_ops->disable_cb(vq);
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}
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/**
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* virtqueue_enable_cb - restart callbacks after disable_cb.
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* @vq: the struct virtqueue we're talking about.
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*
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* This re-enables callbacks; it returns "false" if there are pending
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* buffers in the queue, to detect a possible race between the driver
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* checking for more work, and enabling callbacks.
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*
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* Caller must ensure we don't call this with other virtqueue
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* operations at the same time (except where noted).
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*/
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static inline bool virtqueue_enable_cb(struct virtqueue *vq)
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{
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return vq->vq_ops->enable_cb(vq);
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}
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/**
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* virtqueue_enable_cb_delayed - restart callbacks after disable_cb.
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* @vq: the struct virtqueue we're talking about.
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*
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* This re-enables callbacks but hints to the other side to delay
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* interrupts until most of the available buffers have been processed;
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* it returns "false" if there are many pending buffers in the queue,
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* to detect a possible race between the driver checking for more work,
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* and enabling callbacks.
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*
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* Caller must ensure we don't call this with other virtqueue
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* operations at the same time (except where noted).
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*/
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static inline bool virtqueue_enable_cb_delayed(struct virtqueue *vq)
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{
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return vq->vq_ops->enable_cb_delayed(vq);
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}
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/**
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* virtqueue_detach_unused_buf - detach first unused buffer
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* @vq: the struct virtqueue we're talking about.
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*
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* Returns NULL or the "data" token handed to virtqueue_add_buf().
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* This is not valid on an active queue; it is useful only for device
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* shutdown.
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*/
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static inline void *virtqueue_detach_unused_buf(struct virtqueue *vq)
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{
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return vq->vq_ops->detach_unused_buf(vq);
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}
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/**
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* virtqueue_get_impl_size - return the size of the virtqueue's implementation
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* @vq: the struct virtqueue containing the implementation of interest.
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*
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* Returns the size of the virtqueue implementation. This is mainly used
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* for boasting to userspace. Unlike other operations, this need not
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* be serialized.
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*/
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static inline unsigned int virtqueue_get_impl_size(struct virtqueue *vq)
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{
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return vq->vq_ops->get_impl_size(vq);
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}
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/**
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* virtio_device - representation of a device using virtio
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* @index: unique position on the virtio bus
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* @dev: underlying device.
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* @id: the device type identification (used to match it with a driver).
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* @config: the configuration ops for this device.
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* @vqs: the list of virtqueues for this device.
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* @features: the features supported by both driver and device.
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* @priv: private pointer for the driver's use.
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*/
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struct virtio_device {
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int index;
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struct device dev;
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struct virtio_device_id id;
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struct virtio_config_ops *config;
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struct list_head vqs;
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/* Note that this is a Linux set_bit-style bitmap. */
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unsigned long features[1];
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void *priv;
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};
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#define dev_to_virtio(dev) container_of(dev, struct virtio_device, dev)
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int register_virtio_device(struct virtio_device *dev);
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void unregister_virtio_device(struct virtio_device *dev);
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/**
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* virtio_driver - operations for a virtio I/O driver
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* @driver: underlying device driver (populate name and owner).
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* @id_table: the ids serviced by this driver.
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* @feature_table: an array of feature numbers supported by this driver.
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* @feature_table_size: number of entries in the feature table array.
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* @probe: the function to call when a device is found. Returns 0 or -errno.
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* @remove: the function to call when a device is removed.
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* @config_changed: optional function to call when the device configuration
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* changes; may be called in interrupt context.
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*/
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struct virtio_driver {
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struct device_driver driver;
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const struct virtio_device_id *id_table;
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const unsigned int *feature_table;
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unsigned int feature_table_size;
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int (*probe)(struct virtio_device *dev);
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void (*remove)(struct virtio_device *dev);
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void (*config_changed)(struct virtio_device *dev);
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#ifdef CONFIG_PM
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int (*freeze)(struct virtio_device *dev);
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int (*restore)(struct virtio_device *dev);
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#endif
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};
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int register_virtio_driver(struct virtio_driver *drv);
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void unregister_virtio_driver(struct virtio_driver *drv);
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#endif /* _LINUX_VIRTIO_H */
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