feat(kernel): SystemControl cap for halt, board device table + boot caps to init, RegionAddress syscall, idle loop services irqs

crates/adapter-riscv/src/board.rs

@@ -8,3 +8,29 @@ pub const CLINT_BASE: usize = 0x02000000;
 pub const USER_POOL_BASE: usize = 0x84000000;
 pub const USER_POOL_PAGES: usize = 4096;
 pub const TICK_INTERVAL: u64 = 10_000_000;
+
+/// QEMU virt's PLIC lines.
+const UART_IRQ: u16 = 10;
+const VIRTIO_IRQ_BASE: u16 = 1;
+const VIRTIO_SLOT_SIZE: usize = 0x1000;
+const VIRTIO_SLOTS: usize = VIRTIO_SIZE / VIRTIO_SLOT_SIZE;
+
+/// Every device userspace may drive: the UART and each VirtIO MMIO slot.
+/// The PLIC, CLINT and RAM stay the kernel's.
+pub fn devices() -> Option<[kernel::BoardDevice; 1 + VIRTIO_SLOTS]> {
+    use types::{address::PhysicalAddress, bounded::PageCount, id::IrqId};
+    let one = PageCount::new(1)?;
+    let device = |base: usize, irq: u16| kernel::BoardDevice {
+        base: PhysicalAddress::from_raw(base),
+        pages: one,
+        irq: Some(IrqId::from_raw(irq)),
+    };
+    let mut all = [device(UART_BASE, UART_IRQ); 1 + VIRTIO_SLOTS];
+    for (i, d) in all.iter_mut().skip(1).enumerate() {
+        *d = device(
+            VIRTIO_BASE + i * VIRTIO_SLOT_SIZE,
+            VIRTIO_IRQ_BASE + i as u16,
+        );
+    }
+    Some(all)
+}