mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 12:10:53 +07:00
c45a6816c1
A recent proposed feature addition to the virtio block driver revealed some flaws in the API: in particular, we assume that feature negotiation is complete once a driver's probe function returns. There is nothing in the API to require this, however, and even I didn't notice when it was violated. So instead, we require the driver to specify what features it supports in a table, we can then move the feature negotiation into the virtio core. The intersection of device and driver features are presented in a new 'features' bitmap in the struct virtio_device. Note that this highlights the difference between Linux unsigned-long bitmaps where each unsigned long is in native endian, and a straight-forward little-endian array of bytes. Drivers can still remove feature bits in their probe routine if they really have to. API changes: - dev->config->feature() no longer gets and acks a feature. - drivers should advertise their features in the 'feature_table' field - use virtio_has_feature() for extra sanity when checking feature bits Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
121 lines
4.2 KiB
C
121 lines
4.2 KiB
C
#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).
|
|
* @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
|
|
{
|
|
void (*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.
|
|
* @disable_cb: disable callbacks
|
|
* vq: the struct virtqueue we're talking about.
|
|
* Note that this is not necessarily synchronous, hence unreliable and only
|
|
* useful as an optimization.
|
|
* @enable_cb: restart callbacks after disable_cb.
|
|
* vq: the struct virtqueue we're talking about.
|
|
* This re-enables callbacks; it returns "false" if there are pending
|
|
* buffers in the queue, to detect a possible race between the driver
|
|
* checking for more work, and enabling callbacks.
|
|
*
|
|
* Locking rules are straightforward: the driver is responsible for
|
|
* locking. No two operations may be invoked simultaneously, with the exception
|
|
* of @disable_cb.
|
|
*
|
|
* 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);
|
|
|
|
void (*disable_cb)(struct virtqueue *vq);
|
|
bool (*enable_cb)(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.
|
|
* @features: the features supported by both driver and 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;
|
|
/* Note that this is a Linux set_bit-style bitmap. */
|
|
unsigned long features[1];
|
|
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.
|
|
* @feature_table: an array of feature numbers supported by this device.
|
|
* @feature_table_size: number of entries in the feature table array.
|
|
* @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.
|
|
* @config_changed: optional function to call when the device configuration
|
|
* changes; may be called in interrupt context.
|
|
*/
|
|
struct virtio_driver {
|
|
struct device_driver driver;
|
|
const struct virtio_device_id *id_table;
|
|
const unsigned int *feature_table;
|
|
unsigned int feature_table_size;
|
|
int (*probe)(struct virtio_device *dev);
|
|
void (*remove)(struct virtio_device *dev);
|
|
void (*config_changed)(struct virtio_device *dev);
|
|
};
|
|
|
|
int register_virtio_driver(struct virtio_driver *drv);
|
|
void unregister_virtio_driver(struct virtio_driver *drv);
|
|
#endif /* _LINUX_VIRTIO_H */
|