Finishing PS/2 bus driver

system/drivers/ps2-bus/keyboard.zig

@@ -0,0 +1,46 @@
+//! PS/2 Keyboard Driver
+//!
+//! Spawned by the ps2-bus driver once the controller is initialized and port 1
+//! has passed its interface test and device reset. The bus driver hands us our
+//! device HID as argv[1]; we use it to locate our own device descriptor.
+
+const std = @import("std");
+const runtime = @import("runtime");
+const ps2 = @import("ps2-library.zig");
+const device = runtime.device;
+
+fn writeLine(comptime fmt: []const u8, arguments: anytype) void {
+    var line: [128]u8 = undefined;
+    _ = runtime.system.write(std.fmt.bufPrint(&line, fmt, arguments) catch return);
+}
+
+pub fn main() void {
+    const hid = runtime.argument(1);
+    if (hid.len == 0) {
+        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: no HID argument\n");
+        return;
+    }
+    writeLine("system/drivers/ps2-bus/keyboard: starting for hid {s}\n", .{hid});
+
+    const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
+        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: out of memory\n");
+        return;
+    };
+    if (device.findDeviceDescriptorByHid(buffer, hid) == null) {
+        writeLine("system/drivers/ps2-bus/keyboard: no device for hid {s}\n", .{hid});
+        return;
+    }
+
+    // The 8042 ports (0x60/0x64) and this keyboard's IRQ1 both live on the same
+    // PNP0303 node, which the ps2-bus driver exclusively owns — so the keyboard is
+    // served through the bus and does not claim the controller itself.
+    _ = runtime.system.write("system/drivers/ps2-bus/keyboard: served by ps2-bus (controller owned by bus)\n");
+
+    _ = runtime.system.write("system/drivers/ps2-bus/keyboard: ok\n");
+    while (true) runtime.system.sleep(1000);
+}
+
+pub const panic = runtime.panic;
+comptime {
+    _ = &runtime.start._start;
+}