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129 lines
4.7 KiB
C
129 lines
4.7 KiB
C
#include "types.h"
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/*
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* References:
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* 1. https://github.com/ianchen0119/xv6-riscv/blob/riscv/kernel/virtio.h
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* 2. https://github.com/sgmarz/osblog/blob/master/risc_v/src/virtio.rs
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*/
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#define VIRTIO_MMIO_BASE 0x10001000
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/* OFFSET */
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#define VIRTIO_MMIO_MAGIC_VALUE 0x000 // Magic value must be 0x74726976
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#define VIRTIO_MMIO_VERSION 0x004 // Version: 1 (Legacy)
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/*
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* Device ID:
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* 1 (Network Device)
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* 2 (Block Device)
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* 4 (Random number generator Device)
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* 16 (GPU Device)
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* 18 (Input Device)
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*/
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#define VIRTIO_MMIO_DEVICE_ID 0x008
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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_GUEST_PAGE_SIZE 0x028 // page size for PFN, write-only
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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_ALIGN 0x03c // used ring alignment, write-only
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#define VIRTIO_MMIO_QUEUE_PFN 0x040 // physical page number for queue, read/write
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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_QueueDescLow 0x080
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#define VIRTIO_MMIO_QueueDescHigh 0x084
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#define VIRTIO_MMIO_QueueAvailLow 0x090
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#define VIRTIO_MMIO_QueueAvailHigh 0x094
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#define VIRTIO_MMIO_QueueUsedLow 0x0a0
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#define VIRTIO_MMIO_QueueUsedHigh 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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#define NUM 8
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// 描述符包含這些訊息: 地址，地址長度，某些標誌和其他信息。使用此描述符，我們可以將設備指向 RAM 中任何緩衝區的內存地址。
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typedef struct virtq_desc
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{
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/*
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* addr: 我們可以在 64-bit 內存地址內的任何位置告訴設備存儲位置。
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* len: 讓 Device 知道有多少內存可用。
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* flags: 用於控制 descriptor 。
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* next: 告訴 Device 下一個描述符的 Index 。如果指定了 VIRTQ_DESC_F_NEXT， Device 僅讀取該字段。否則無效。
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*/
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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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} virtq_desc_t;
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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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#define VRING_DESC_F_INDIRECT 4 // buffer contains a list of buffer descriptors
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/*
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* 用來存放 descriptor 的索引，當 Device 收到通知時，它會檢查 AvailableRing 確認需要讀取哪些 Descriptor 。
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* 注意: Descriptor 和 AvailableRing 都存儲在 RAM 中。
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*/
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typedef struct virtq_avail
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{
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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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} virtq_avail_t;
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/*
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* 當內部的 Index 與 UsedRing 的 Index 相等，代表所有資料都已經被讀取，這個 Device 是唯一需要被寫進 Index 的。
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*/
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typedef struct virtq_used_elem
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{
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uint32 id; // index of start of completed descriptor chain
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uint32 len;
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} virtq_used_elem_t;
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/*
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* Device 可以使用 UsedRing 向 OS 發送訊息。
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* Device 通常使用它來告知 OS 它已完成先前通知的請求。
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* AvailableRing 與 UsedRing 非常相似，差異在於: OS 需要查看 UsedRing 得知哪個 Descriptor 已經被服務。
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*/
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typedef struct virtq_used
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{
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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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} virtq_used_t;
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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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typedef struct virtio_blk_req
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{
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uint32 type; // VIRTIO_BLK_T_IN or ..._OUT
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uint32 reserved; // 將 Header 擴充到 16-byte ，並將 64-bit sector 移到正確的位置。
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uint64 sector;
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} virtio_blk_req_t; |