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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>
112 lines
4.2 KiB
C
112 lines
4.2 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 config. */
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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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/* Feature byte (actually 7 bits availabe): */
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/* Requirements/features of the virtio implementation. */
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#define VIRTIO_CONFIG_F_VIRTIO 1
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/* Requirements/features of the virtqueue (may have more than one). */
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#define VIRTIO_CONFIG_F_VIRTQUEUE 2
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#ifdef __KERNEL__
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struct virtio_device;
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/**
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* virtio_config_ops - operations for configuring a virtio device
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* @find: search for the next configuration field of the given type.
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* vdev: the virtio_device
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* type: the feature type
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* len: the (returned) length of the field if found.
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* Returns a token if found, or NULL. Never returnes the same field twice
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* (ie. it's used up).
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* @get: read the value of a configuration field after find().
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* vdev: the virtio_device
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* token: the token returned from find().
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* buf: the buffer to write the field value into.
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* len: the length of the buffer (given by find()).
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* Note that contents are conventionally little-endian.
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* @set: write the value of a configuration field after find().
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* vdev: the virtio_device
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* token: the token returned from find().
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* buf: the buffer to read the field value from.
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* len: the length of the buffer (given by find()).
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* Note that contents are conventionally little-endian.
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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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* @find_vq: find the first VIRTIO_CONFIG_F_VIRTQUEUE and create a virtqueue.
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* vdev: the virtio_device
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* callback: the virqtueue callback
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* Returns the new virtqueue or ERR_PTR().
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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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void *(*find)(struct virtio_device *vdev, u8 type, unsigned *len);
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void (*get)(struct virtio_device *vdev, void *token,
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void *buf, unsigned len);
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void (*set)(struct virtio_device *vdev, void *token,
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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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struct virtqueue *(*find_vq)(struct virtio_device *vdev,
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bool (*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 - get a single virtio config and mark it used.
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* @config: the virtio config space
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* @type: 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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* Once used, the config type is marked with VIRTIO_CONFIG_F_USED so it can't
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* be found again. This version does endian conversion. */
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#define virtio_config_val(vdev, type, v) ({ \
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int _err = __virtio_config_val((vdev),(type),(v),sizeof(*(v))); \
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\
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BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
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&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
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if (!_err) { \
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switch (sizeof(*(v))) { \
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case 2: le16_to_cpus((__u16 *) v); break; \
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case 4: le32_to_cpus((__u32 *) v); break; \
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case 8: le64_to_cpus((__u64 *) v); break; \
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} \
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} \
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_err; \
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})
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int __virtio_config_val(struct virtio_device *dev,
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u8 type, void *val, size_t size);
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/**
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* virtio_use_bit - helper to use a feature bit in a bitfield value.
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* @dev: the virtio device
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* @token: the token as returned from vdev->config->find().
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* @len: the length of the field.
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* @bitnum: the bit to test.
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*
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* If handed a NULL token, it returns false, otherwise returns bit status.
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* If it's one, it sets the mirroring acknowledgement bit. */
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int virtio_use_bit(struct virtio_device *vdev,
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void *token, unsigned int len, unsigned int bitnum);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_VIRTIO_CONFIG_H */
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