kernel_io.h

#pragma once

#define SECTOR_SIZE 512
#define VIRTQ_ENTRY_NUM 16
#define VIRTIO_DEVICE_BLK 2
#define VIRTIO_BLK_PADDR 0x10001000
#define VIRTIO_REG_MAGIC 0x00
#define VIRTIO_REG_VERSION 0x04
#define VIRTIO_REG_DEVICE_ID 0x08
#define VIRTIO_REG_QUEUE_SEL 0x30
#define VIRTIO_REG_QUEUE_NUM_MAX 0x34
#define VIRTIO_REG_QUEUE_NUM 0x38
#define VIRTIO_REG_QUEUE_ALIGN 0x3c
#define VIRTIO_REG_QUEUE_PFN 0x40
#define VIRTIO_REG_QUEUE_READY 0x44
#define VIRTIO_REG_QUEUE_NOTIFY 0x50
#define VIRTIO_REG_DEVICE_STATUS 0x70
#define VIRTIO_REG_DEVICE_CONFIG 0x100
#define VIRTIO_STATUS_ACK 1
#define VIRTIO_STATUS_DRIVER 2
#define VIRTIO_STATUS_DRIVER_OK 4
#define VIRTIO_STATUS_FEAT_OK 8
#define VIRTQ_DESC_F_NEXT 1
#define VIRTQ_DESC_F_WRITE 2
#define VIRTQ_AVAIL_F_NO_INTERRUPT 1
#define VIRTIO_BLK_T_IN 0
#define VIRTIO_BLK_T_OUT 1

// Virtqueue Descriptor 区域条目
struct virtq_desc
{
    uint64_t addr;
    uint32_t len;
    uint16_t flags;
    uint16_t next;
} __attribute__((packed));

// Virtqueue Available Ring
struct virtq_avail
{
    uint16_t flags;
    uint16_t index;
    uint16_t ring[VIRTQ_ENTRY_NUM];
} __attribute__((packed));

// Virtqueue Used Ring 条目
struct virtq_used_elem
{
    uint32_t id;
    uint32_t len;
} __attribute__((packed));

// Virtqueue Used Ring
struct virtq_used
{
    uint16_t flags;
    uint16_t index;
    struct virtq_used_elem ring[VIRTQ_ENTRY_NUM];
} __attribute__((packed));

// Virtqueue
struct virtio_virtq
{
    struct virtq_desc descs[VIRTQ_ENTRY_NUM];
    struct virtq_avail avail;
    struct virtq_used used __attribute__((aligned(PAGE_SIZE)));
    int queue_index;
    volatile uint16_t *used_index;
    uint16_t last_used_index;
} __attribute__((packed));

// Virtio-blk 请求
struct virtio_blk_req
{
    // 第一个描述符：设备只读
    uint32_t type;
    uint32_t reserved;
    uint64_t sector;

    // 第二个描述符：如果是读操作则设备可写(VIRTQ_DESC_F_WRITE)
    uint8_t data[512];

    // 第三个描述符：设备可写(VIRTQ_DESC_F_WRITE)
    uint8_t status;
} __attribute__((packed));

void virtio_blk_init(void);
struct virtio_virtq *virtq_init(unsigned index);
void virtq_kick(struct virtio_virtq *vq, int desc_index);
bool virtq_is_busy(struct virtio_virtq *vq);
void read_write_disk(void *buf, unsigned sector, int is_write);