add device platform module with ACPI support

src/kernel/main.zig

@@ -5,6 +5,7 @@ const console = @import("console.zig");
 const pmm = @import("pmm.zig");
 const heap = @import("heap.zig");
 const scheduler = @import("scheduler.zig");
+const platform = @import("platform");
 const tests = @import("tests.zig");
 const build_options = @import("build_options");
 const BootInfo = danos.BootInfo;
@@ -102,6 +103,38 @@ fn kmain(boot_info: *const BootInfo) noreturn {
     const s2 = pmm.stats();
     serial0.debugPrint("  Kernel footprint: {d} KiB\n", .{kib(s1.free_frames - s2.free_frames)});
 
+    // Enumerate hardware from the firmware tables (ACPI here) into a generic
+    // device tree, then list it. Discovery walks ACPI memory directly (identity-
+    // mapped) and maps PCIe config space on demand via the VMM. A failure here is
+    // not fatal yet — log it and carry on.
+    const hal = platform.Hal{
+        .mapMmio = arch.mapPage,
+        .pioRead = arch.pioRead,
+        .pioWrite = arch.pioWrite,
+    };
+    if (platform.discover(boot_info, heap.allocator(), hal)) |devtree| {
+        var dt = devtree;
+        serial0.debugWrite("\ndanos: device discovery online\n");
+        dt.dump(console.SerialConsole.debugWrite);
+
+        // Power register map extracted from the FADT + AML, for confidence it parsed.
+        const pw = platform.powerInfo();
+        serial0.debugWrite("danos: power\n");
+        serial0.debugPrint("  pm1a_cnt   : {s} 0x{x} (width {d})\n", .{ if (pw.pm1a_cnt.mmio) "mmio" else "io", pw.pm1a_cnt.address, pw.pm1a_cnt.width });
+        if (pw.s5) |s| {
+            serial0.debugPrint("  S5 slp_typ : a={d} b={d}\n", .{ s.slp_typ_a, s.slp_typ_b });
+        } else {
+            serial0.debugWrite("  S5 slp_typ : (not found)\n");
+        }
+        serial0.debugPrint("  reset      : supported={} {s} 0x{x} val 0x{x}\n", .{ pw.reset_supported, if (pw.reset.mmio) "mmio" else "io", pw.reset.address, pw.reset_value });
+
+        // AML namespace parse integrity: consumed should equal total.
+        const am = platform.amlStats();
+        serial0.debugPrint("  aml        : {d} namespace nodes, parsed {d}/{d} bytes\n", .{ am.nodes, am.consumed, am.total });
+    } else |err| {
+        serial0.debugPrint("\ndanos: device discovery failed: {s}\n", .{@errorName(err)});
+    }
+
     // Register the current context as the first task before enabling preemption.
     scheduler.init(4);
     serial0.debugWrite("\ndanos: scheduler online\n");