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72e61eb40b
A recent proposed feature addition to the virtio block driver revealed some flaws in the API, in particular how easy it is to break big endian machines. The virtio config space was originally chosen to be little-endian, because we thought the config might be part of the PCI config space for virtio_pci. It's actually a separate mmio region, so that argument holds little water; as only x86 is currently using the virtio mechanism, we can change this (but must do so now, before the impending s390 merge). API changes: - __virtio_config_val() just becomes a striaght vdev->config_get() call. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
94 lines
3.4 KiB
C
94 lines
3.4 KiB
C
#ifndef _LINUX_VIRTIO_CONFIG_H
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#define _LINUX_VIRTIO_CONFIG_H
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/* Virtio devices use a standardized configuration space to define their
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* features and pass configuration information, but each implementation can
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* store and access that space differently. */
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#include <linux/types.h>
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/* Status byte for guest to report progress, and synchronize features. */
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/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
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#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
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/* We have found a driver for the device. */
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#define VIRTIO_CONFIG_S_DRIVER 2
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/* Driver has used its parts of the config, and is happy */
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#define VIRTIO_CONFIG_S_DRIVER_OK 4
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/* We've given up on this device. */
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#define VIRTIO_CONFIG_S_FAILED 0x80
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#ifdef __KERNEL__
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#include <linux/virtio.h>
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/**
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* virtio_config_ops - operations for configuring a virtio device
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* @feature: search for a feature in this config
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* vdev: the virtio_device
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* bit: the feature bit
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* Returns true if the feature is supported. Acknowledges the feature
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* so the host can see it.
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* @get: read the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to write the field value into.
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* len: the length of the buffer
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* @set: write the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to read the field value from.
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* len: the length of the buffer
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* @get_status: read the status byte
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* vdev: the virtio_device
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* Returns the status byte
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* @set_status: write the status byte
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* vdev: the virtio_device
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* status: the new status byte
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* @reset: reset the device
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* vdev: the virtio device
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* After this, status and feature negotiation must be done again
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* @find_vq: find a virtqueue and instantiate it.
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* vdev: the virtio_device
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* index: the 0-based virtqueue number in case there's more than one.
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* callback: the virqtueue callback
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* Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
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* @del_vq: free a virtqueue found by find_vq().
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*/
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struct virtio_config_ops
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{
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bool (*feature)(struct virtio_device *vdev, unsigned bit);
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void (*get)(struct virtio_device *vdev, unsigned offset,
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void *buf, unsigned len);
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void (*set)(struct virtio_device *vdev, unsigned offset,
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const void *buf, unsigned len);
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u8 (*get_status)(struct virtio_device *vdev);
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void (*set_status)(struct virtio_device *vdev, u8 status);
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void (*reset)(struct virtio_device *vdev);
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struct virtqueue *(*find_vq)(struct virtio_device *vdev,
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unsigned index,
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void (*callback)(struct virtqueue *));
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void (*del_vq)(struct virtqueue *vq);
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};
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/**
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* virtio_config_val - look for a feature and get a virtio config entry.
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* @vdev: the virtio device
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* @fbit: the feature bit
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* @offset: the type to search for.
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* @val: a pointer to the value to fill in.
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*
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* The return value is -ENOENT if the feature doesn't exist. Otherwise
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* the config value is copied into whatever is pointed to by v. */
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#define virtio_config_val(vdev, fbit, offset, v) \
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virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(v))
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static inline int virtio_config_buf(struct virtio_device *vdev,
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unsigned int fbit,
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unsigned int offset,
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void *buf, unsigned len)
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{
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if (!vdev->config->feature(vdev, fbit))
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return -ENOENT;
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vdev->config->get(vdev, offset, buf, len);
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return 0;
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}
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#endif /* __KERNEL__ */
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#endif /* _LINUX_VIRTIO_CONFIG_H */
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