97 lines
3.4 KiB
C
97 lines
3.4 KiB
C
//
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// virtio device definitions.
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// for both the mmio interface, and virtio descriptors.
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// only tested with qemu.
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//
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// the virtio spec:
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// https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf
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//
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// virtio mmio control registers, mapped starting at 0x10001000.
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// from qemu virtio_mmio.h
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#define VIRTIO_MMIO_MAGIC_VALUE 0x000 // 0x74726976
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#define VIRTIO_MMIO_VERSION 0x004 // version; should be 2
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#define VIRTIO_MMIO_DEVICE_ID 0x008 // device type; 1 is net, 2 is disk
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#define VIRTIO_MMIO_VENDOR_ID 0x00c // 0x554d4551
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#define VIRTIO_MMIO_DEVICE_FEATURES 0x010
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#define VIRTIO_MMIO_DRIVER_FEATURES 0x020
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#define VIRTIO_MMIO_QUEUE_SEL 0x030 // select queue, write-only
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#define VIRTIO_MMIO_QUEUE_NUM_MAX 0x034 // max size of current queue, read-only
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#define VIRTIO_MMIO_QUEUE_NUM 0x038 // size of current queue, write-only
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#define VIRTIO_MMIO_QUEUE_READY 0x044 // ready bit
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#define VIRTIO_MMIO_QUEUE_NOTIFY 0x050 // write-only
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#define VIRTIO_MMIO_INTERRUPT_STATUS 0x060 // read-only
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#define VIRTIO_MMIO_INTERRUPT_ACK 0x064 // write-only
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#define VIRTIO_MMIO_STATUS 0x070 // read/write
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#define VIRTIO_MMIO_QUEUE_DESC_LOW 0x080 // physical address for descriptor table, write-only
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#define VIRTIO_MMIO_QUEUE_DESC_HIGH 0x084
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#define VIRTIO_MMIO_DRIVER_DESC_LOW 0x090 // physical address for available ring, write-only
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#define VIRTIO_MMIO_DRIVER_DESC_HIGH 0x094
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#define VIRTIO_MMIO_DEVICE_DESC_LOW 0x0a0 // physical address for used ring, write-only
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#define VIRTIO_MMIO_DEVICE_DESC_HIGH 0x0a4
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// status register bits, from qemu virtio_config.h
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#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
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#define VIRTIO_CONFIG_S_DRIVER 2
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#define VIRTIO_CONFIG_S_DRIVER_OK 4
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#define VIRTIO_CONFIG_S_FEATURES_OK 8
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// device feature bits
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#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
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#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
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#define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */
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#define VIRTIO_BLK_F_MQ 12 /* support more than one vq */
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#define VIRTIO_F_ANY_LAYOUT 27
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#define VIRTIO_RING_F_INDIRECT_DESC 28
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#define VIRTIO_RING_F_EVENT_IDX 29
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// this many virtio descriptors.
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// must be a power of two.
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#define NUM 8
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// a single descriptor, from the spec.
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struct virtq_desc {
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uint64 addr;
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uint32 len;
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uint16 flags;
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uint16 next;
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};
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#define VRING_DESC_F_NEXT 1 // chained with another descriptor
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#define VRING_DESC_F_WRITE 2 // device writes (vs read)
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// the (entire) avail ring, from the spec.
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struct virtq_avail {
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uint16 flags; // always zero
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uint16 idx; // driver will write ring[idx] next
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uint16 ring[NUM]; // descriptor numbers of chain heads
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uint16 unused;
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};
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// one entry in the "used" ring, with which the
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// device tells the driver about completed requests.
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struct virtq_used_elem {
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uint32 id; // index of start of completed descriptor chain
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uint32 len;
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};
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struct virtq_used {
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uint16 flags; // always zero
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uint16 idx; // device increments when it adds a ring[] entry
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struct virtq_used_elem ring[NUM];
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};
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// these are specific to virtio block devices, e.g. disks,
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// described in Section 5.2 of the spec.
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#define VIRTIO_BLK_T_IN 0 // read the disk
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#define VIRTIO_BLK_T_OUT 1 // write the disk
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// the format of the first descriptor in a disk request.
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// to be followed by two more descriptors containing
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// the block, and a one-byte status.
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struct virtio_blk_req {
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uint32 type; // VIRTIO_BLK_T_IN or ..._OUT
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uint32 reserved;
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uint64 sector;
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};
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