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Virtio interface

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This attempts to implement a "virtual I/O" layer which should allow
common drivers to be efficiently used across most virtual I/O
mechanisms.  It will no-doubt need further enhancement.

The virtio drivers add buffers to virtio queues; as the buffers are consumed
the driver "interrupt" callbacks are invoked.

There is also a generic implementation of config space which drivers can query
to get setup information from the host.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
Cc: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Rusty Russell 2007-10-22 11:03:36 +10:00
parent 47436aa4ad
commit ec3d41c4db
10 changed files with 419 additions and 0 deletions
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110
include/linux/virtio.h Normal file
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#ifndef _LINUX_VIRTIO_H
#define _LINUX_VIRTIO_H
/* Everything a virtio driver needs to work with any particular virtio
* implementation. */
#include <linux/types.h>
#include <linux/scatterlist.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/mod_devicetable.h>
/**
* virtqueue - a queue to register buffers for sending or receiving.
* @callback: the function to call when buffers are consumed (can be NULL).
* If this returns false, callbacks are suppressed until vq_ops->restart
* is called.
* @vdev: the virtio device this queue was created for.
* @vq_ops: the operations for this virtqueue (see below).
* @priv: a pointer for the virtqueue implementation to use.
*/
struct virtqueue
{
bool (*callback)(struct virtqueue *vq);
struct virtio_device *vdev;
struct virtqueue_ops *vq_ops;
void *priv;
};
/**
* virtqueue_ops - operations for virtqueue abstraction layer
* @add_buf: expose buffer to other end
* vq: the struct virtqueue we're talking about.
* sg: the description of the buffer(s).
* out_num: the number of sg readable by other side
* in_num: the number of sg which are writable (after readable ones)
* data: the token identifying the buffer.
* Returns 0 or an error.
* @kick: update after add_buf
* vq: the struct virtqueue
* After one or more add_buf calls, invoke this to kick the other side.
* @get_buf: get the next used buffer
* vq: the struct virtqueue we're talking about.
* len: the length written into the buffer
* Returns NULL or the "data" token handed to add_buf.
* @restart: restart callbacks after callback returned false.
* vq: the struct virtqueue we're talking about.
* This returns "false" (and doesn't re-enable) if there are pending
* buffers in the queue, to avoid a race.
* @shutdown: "unadd" all buffers.
* vq: the struct virtqueue we're talking about.
* Remove everything from the queue.
*
* Locking rules are straightforward: the driver is responsible for
* locking. No two operations may be invoked simultaneously.
*
* All operations can be called in any context.
*/
struct virtqueue_ops {
int (*add_buf)(struct virtqueue *vq,
struct scatterlist sg[],
unsigned int out_num,
unsigned int in_num,
void *data);
void (*kick)(struct virtqueue *vq);
void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
bool (*restart)(struct virtqueue *vq);
void (*shutdown)(struct virtqueue *vq);
};
/**
* virtio_device - representation of a device using virtio
* @index: unique position on the virtio bus
* @dev: underlying device.
* @id: the device type identification (used to match it with a driver).
* @config: the configuration ops for this device.
* @priv: private pointer for the driver's use.
*/
struct virtio_device
{
int index;
struct device dev;
struct virtio_device_id id;
struct virtio_config_ops *config;
void *priv;
};
int register_virtio_device(struct virtio_device *dev);
void unregister_virtio_device(struct virtio_device *dev);
/**
* virtio_driver - operations for a virtio I/O driver
* @driver: underlying device driver (populate name and owner).
* @id_table: the ids serviced by this driver.
* @probe: the function to call when a device is found. Returns a token for
* remove, or PTR_ERR().
* @remove: the function when a device is removed.
*/
struct virtio_driver {
struct device_driver driver;
const struct virtio_device_id *id_table;
int (*probe)(struct virtio_device *dev);
void (*remove)(struct virtio_device *dev);
};
int register_virtio_driver(struct virtio_driver *drv);
void unregister_virtio_driver(struct virtio_driver *drv);
#endif /* _LINUX_VIRTIO_H */