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authorRusty Russell <rusty@rustcorp.com.au>2007-10-22 05:03:36 +0400
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 09:49:54 +0400
commitec3d41c4db4c21164332826ea8d812f94f2f6886 (patch)
tree9b947e900745cfcc4df7409c6ba5583428964215 /include/linux/virtio_config.h
parent47436aa4ad054c1c7c8231618e86ebd9305308dc (diff)
downloadlinux-ec3d41c4db4c21164332826ea8d812f94f2f6886.tar.xz
Virtio interface
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>
Diffstat (limited to 'include/linux/virtio_config.h')
-rw-r--r--include/linux/virtio_config.h111
1 files changed, 111 insertions, 0 deletions
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
new file mode 100644
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+++ b/include/linux/virtio_config.h
@@ -0,0 +1,111 @@
+#ifndef _LINUX_VIRTIO_CONFIG_H
+#define _LINUX_VIRTIO_CONFIG_H
+/* Virtio devices use a standardized configuration space to define their
+ * features and pass configuration information, but each implementation can
+ * store and access that space differently. */
+#include <linux/types.h>
+
+/* Status byte for guest to report progress, and synchronize config. */
+/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
+#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
+/* We have found a driver for the device. */
+#define VIRTIO_CONFIG_S_DRIVER 2
+/* Driver has used its parts of the config, and is happy */
+#define VIRTIO_CONFIG_S_DRIVER_OK 4
+/* We've given up on this device. */
+#define VIRTIO_CONFIG_S_FAILED 0x80
+
+/* Feature byte (actually 7 bits availabe): */
+/* Requirements/features of the virtio implementation. */
+#define VIRTIO_CONFIG_F_VIRTIO 1
+/* Requirements/features of the virtqueue (may have more than one). */
+#define VIRTIO_CONFIG_F_VIRTQUEUE 2
+
+#ifdef __KERNEL__
+struct virtio_device;
+
+/**
+ * virtio_config_ops - operations for configuring a virtio device
+ * @find: search for the next configuration field of the given type.
+ * vdev: the virtio_device
+ * type: the feature type
+ * len: the (returned) length of the field if found.
+ * Returns a token if found, or NULL. Never returnes the same field twice
+ * (ie. it's used up).
+ * @get: read the value of a configuration field after find().
+ * vdev: the virtio_device
+ * token: the token returned from find().
+ * buf: the buffer to write the field value into.
+ * len: the length of the buffer (given by find()).
+ * Note that contents are conventionally little-endian.
+ * @set: write the value of a configuration field after find().
+ * vdev: the virtio_device
+ * token: the token returned from find().
+ * buf: the buffer to read the field value from.
+ * len: the length of the buffer (given by find()).
+ * Note that contents are conventionally little-endian.
+ * @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
+ * @find_vq: find the first VIRTIO_CONFIG_F_VIRTQUEUE and create a virtqueue.
+ * vdev: the virtio_device
+ * callback: the virqtueue callback
+ * Returns the new virtqueue or ERR_PTR().
+ * @del_vq: free a virtqueue found by find_vq().
+ */
+struct virtio_config_ops
+{
+ void *(*find)(struct virtio_device *vdev, u8 type, unsigned *len);
+ void (*get)(struct virtio_device *vdev, void *token,
+ void *buf, unsigned len);
+ void (*set)(struct virtio_device *vdev, void *token,
+ const void *buf, unsigned len);
+ u8 (*get_status)(struct virtio_device *vdev);
+ void (*set_status)(struct virtio_device *vdev, u8 status);
+ struct virtqueue *(*find_vq)(struct virtio_device *vdev,
+ bool (*callback)(struct virtqueue *));
+ void (*del_vq)(struct virtqueue *vq);
+};
+
+/**
+ * virtio_config_val - get a single virtio config and mark it used.
+ * @config: the virtio config space
+ * @type: the type to search for.
+ * @val: a pointer to the value to fill in.
+ *
+ * Once used, the config type is marked with VIRTIO_CONFIG_F_USED so it can't
+ * be found again. This version does endian conversion. */
+#define virtio_config_val(vdev, type, v) ({ \
+ int _err = __virtio_config_val((vdev),(type),(v),sizeof(*(v))); \
+ \
+ BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
+ && sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
+ if (!_err) { \
+ switch (sizeof(*(v))) { \
+ case 2: le16_to_cpus((__u16 *) v); break; \
+ case 4: le32_to_cpus((__u32 *) v); break; \
+ case 8: le64_to_cpus((__u64 *) v); break; \
+ } \
+ } \
+ _err; \
+})
+
+int __virtio_config_val(struct virtio_device *dev,
+ u8 type, void *val, size_t size);
+
+/**
+ * virtio_use_bit - helper to use a feature bit in a bitfield value.
+ * @dev: the virtio device
+ * @token: the token as returned from vdev->config->find().
+ * @len: the length of the field.
+ * @bitnum: the bit to test.
+ *
+ * If handed a NULL token, it returns false, otherwise returns bit status.
+ * If it's one, it sets the mirroring acknowledgement bit. */
+int virtio_use_bit(struct virtio_device *vdev,
+ void *token, unsigned int len, unsigned int bitnum);
+#endif /* __KERNEL__ */
+#endif /* _LINUX_VIRTIO_CONFIG_H */