add device platform module with ACPI support

src/kernel/tests.zig

@@ -12,6 +12,7 @@
 const std = @import("std");
 const danos = @import("danos");
 const arch = @import("arch");
+const platform = @import("platform");
 const pmm = @import("pmm.zig");
 const heap = @import("heap.zig");
 const sched = @import("scheduler.zig");
@@ -77,11 +78,39 @@ pub fn run(case: []const u8, boot_info: *const BootInfo) void {
         faultNoExecute();
     } else if (eql(case, "fault-null")) {
         faultNull();
+    } else if (eql(case, "poweroff")) {
+        powerTest(.off);
+    } else if (eql(case, "reboot")) {
+        powerTest(.reboot);
     } else {
         log("DANOS-TEST-RESULT: FAIL (unknown case '{s}')\n", .{case});
     }
 }
 
+fn platformHal() platform.Hal {
+    return .{
+        .mapMmio = arch.mapPage,
+        .pioRead = arch.pioRead,
+        .pioWrite = arch.pioWrite,
+    };
+}
+
+/// Drive an ACPI power transition. On success the machine powers off or resets,
+/// so QEMU exits — the harness observes the process exit. If control returns, the
+/// transition failed and we emit a FAIL result.
+fn powerTest(comptime action: enum { off, reboot }) void {
+    const name = if (action == .off) "poweroff" else "reboot";
+    log("DANOS-TEST-BEGIN: {s}\n", .{name});
+    const hal = platformHal();
+    log("DANOS-POWER: attempting {s}\n", .{name});
+    switch (action) {
+        .off => platform.shutdown(hal),
+        .reboot => platform.reboot(hal),
+    }
+    check("power transition took effect", false);
+    result();
+}
+
 const BootInfo = danos.BootInfo;
 
 fn eql(a: []const u8, b: []const u8) bool {