blob: 29b9104232b40c038bf29969d9c63795e8575fce [file] [log] [blame]
#include <linux/err.h>
#include <linux/bug.h>
#include <linux/virtio.h>
#include <uapi/linux/virtio_config.h>
* virtio_config_ops - operations for configuring a virtio device
* @get: read the value of a configuration field
* vdev: the virtio_device
* offset: the offset of the configuration field
* buf: the buffer to write the field value into.
* len: the length of the buffer
* @set: write the value of a configuration field
* vdev: the virtio_device
* offset: the offset of the configuration field
* buf: the buffer to read the field value from.
* len: the length of the buffer
* @get_status: read the status byte
* vdev: the virtio_device
* Returns the status byte
* @set_status: write the status byte
* vdev: the virtio_device
* status: the new status byte
* @reset: reset the device
* vdev: the virtio device
* After this, status and feature negotiation must be done again
* Device must not be reset from its vq/config callbacks, or in
* parallel with being added/removed.
* @find_vqs: find virtqueues and instantiate them.
* vdev: the virtio_device
* nvqs: the number of virtqueues to find
* vqs: on success, includes new virtqueues
* callbacks: array of callbacks, for each virtqueue
* include a NULL entry for vqs that do not need a callback
* names: array of virtqueue names (mainly for debugging)
* include a NULL entry for vqs unused by driver
* Returns 0 on success or error status
* @del_vqs: free virtqueues found by find_vqs().
* @get_features: get the array of feature bits for this device.
* vdev: the virtio_device
* Returns the first 32 feature bits (all we currently need).
* @finalize_features: confirm what device features we'll be using.
* vdev: the virtio_device
* This gives the final feature bits for the device: it can change
* the dev->feature bits if it wants.
* @bus_name: return the bus name associated with the device
* vdev: the virtio_device
* This returns a pointer to the bus name a la pci_name from which
* the caller can then copy.
* @set_vq_affinity: set the affinity for a virtqueue.
typedef void vq_callback_t(struct virtqueue *);
struct virtio_config_ops {
void (*get)(struct virtio_device *vdev, unsigned offset,
void *buf, unsigned len);
void (*set)(struct virtio_device *vdev, unsigned offset,
const void *buf, unsigned len);
u8 (*get_status)(struct virtio_device *vdev);
void (*set_status)(struct virtio_device *vdev, u8 status);
void (*reset)(struct virtio_device *vdev);
int (*find_vqs)(struct virtio_device *, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
const char *names[]);
void (*del_vqs)(struct virtio_device *);
u32 (*get_features)(struct virtio_device *vdev);
void (*finalize_features)(struct virtio_device *vdev);
const char *(*bus_name)(struct virtio_device *vdev);
int (*set_vq_affinity)(struct virtqueue *vq, int cpu);
/* If driver didn't advertise the feature, it will never appear. */
void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
unsigned int fbit);
* virtio_has_feature - helper to determine if this device has this feature.
* @vdev: the device
* @fbit: the feature bit
static inline bool virtio_has_feature(const struct virtio_device *vdev,
unsigned int fbit)
/* Did you forget to fix assumptions on max features? */
if (__builtin_constant_p(fbit))
BUILD_BUG_ON(fbit >= 32);
BUG_ON(fbit >= 32);
virtio_check_driver_offered_feature(vdev, fbit);
return test_bit(fbit, vdev->features);
* virtio_config_val - look for a feature and get a virtio config entry.
* @vdev: the virtio device
* @fbit: the feature bit
* @offset: the type to search for.
* @v: a pointer to the value to fill in.
* The return value is -ENOENT if the feature doesn't exist. Otherwise
* the config value is copied into whatever is pointed to by v. */
#define virtio_config_val(vdev, fbit, offset, v) \
virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
#define virtio_config_val_len(vdev, fbit, offset, v, len) \
virtio_config_buf((vdev), (fbit), (offset), (v), (len))
static inline int virtio_config_buf(struct virtio_device *vdev,
unsigned int fbit,
unsigned int offset,
void *buf, unsigned len)
if (!virtio_has_feature(vdev, fbit))
return -ENOENT;
vdev->config->get(vdev, offset, buf, len);
return 0;
static inline
struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
vq_callback_t *c, const char *n)
vq_callback_t *callbacks[] = { c };
const char *names[] = { n };
struct virtqueue *vq;
int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
if (err < 0)
return ERR_PTR(err);
return vq;
static inline
const char *virtio_bus_name(struct virtio_device *vdev)
if (!vdev->config->bus_name)
return "virtio";
return vdev->config->bus_name(vdev);
* virtqueue_set_affinity - setting affinity for a virtqueue
* @vq: the virtqueue
* @cpu: the cpu no.
* Pay attention the function are best-effort: the affinity hint may not be set
* due to config support, irq type and sharing.
static inline
int virtqueue_set_affinity(struct virtqueue *vq, int cpu)
struct virtio_device *vdev = vq->vdev;
if (vdev->config->set_vq_affinity)
return vdev->config->set_vq_affinity(vq, cpu);
return 0;