#![no_std]
#![no_main]

#[macro_use]
extern crate log;
#[macro_use]
extern crate opensbi_rt;

use device_tree::util::SliceRead;
use device_tree::{DeviceTree, Node};
use log::LevelFilter;
use virtio_drivers::{DeviceType, VirtIOBlk, VirtIOHeader};

mod virtio_impl;

#[no_mangle]
extern "C" fn main(_hartid: usize, device_tree_paddr: usize) {
    log::set_max_level(LevelFilter::Info);
    init_dt(device_tree_paddr);
}

fn init_dt(dtb: usize) {
    info!("device tree @ {:#x}", dtb);
    struct DtbHeader {
        be_magic: u32,
        be_size: u32,
    }
    let header = unsafe { &*(dtb as *const DtbHeader) };
    let magic = u32::from_be(header.be_magic);
    const DEVICE_TREE_MAGIC: u32 = 0xd00dfeed;
    assert_eq!(magic, DEVICE_TREE_MAGIC);
    let size = u32::from_be(header.be_size);
    let dtb_data = unsafe { core::slice::from_raw_parts(dtb as *const u8, size as usize) };
    let dt = DeviceTree::load(dtb_data).expect("failed to parse device tree");
    walk_dt_node(&dt.root);
}

fn walk_dt_node(dt: &Node) {
    if let Ok(compatible) = dt.prop_str("compatible") {
        if compatible == "virtio,mmio" {
            virtio_probe(dt);
        }
    }
    for child in dt.children.iter() {
        walk_dt_node(child);
    }
}

fn virtio_probe(node: &Node) {
    if let Some(reg) = node.prop_raw("reg") {
        let paddr = reg.as_slice().read_be_u64(0).unwrap();
        let size = reg.as_slice().read_be_u64(8).unwrap();
        let vaddr = paddr;
        info!("walk dt addr={:#x}, size={:#x}", paddr, size);
        let header = unsafe { &mut *(vaddr as *mut VirtIOHeader) };
        info!(
            "Detected virtio device with vendor id {:#X}",
            header.vendor_id()
        );
        info!("Device tree node {:?}", node);
        match header.device_type() {
            DeviceType::Block => virtio_blk(header),
            t => warn!("Unrecognized virtio device: {:?}", t),
        }
    }
}

fn virtio_blk(header: &'static mut VirtIOHeader) {
    let mut blk = VirtIOBlk::new(header).expect("failed to create blk driver");
    let mut buf = [0u8; 512];
    blk.read_block(0, &mut buf);
    unimplemented!()
}