//! /system/drivers/usb-xhci-bus — the xHCI (USB 3) host-controller bus driver.
//! The device manager spawns **one instance per controller** it discovers (a machine
//! can carry several), passing the controller's device-tree id as argv[1]; this
//! instance claims that device and no other, so multiple instances never fight over
//! hardware. This increment proves the plumbing: parse the id, claim the controller,
//! and report its MMIO window. The next increments map the registers and bring the
//! controller up (reset, rings, port scan), then enumerate the USB devices on the
//! bus with the usb-abi request builders and publish each with `device_register`.

const std = @import("std");
const runtime = @import("runtime");
const device = runtime.device;

/// Format one whole log line and emit it in a single `debug_write`, so concurrent
/// instances (one per controller) can never interleave mid-line.
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(init: runtime.process.Init) void {
    const argument = init.arguments.get(1) orelse {
        _ = runtime.system.write("usb-xhci-bus: missing controller device id (argv[1])\n");
        return;
    };
    const controller_id = std.fmt.parseInt(u64, argument, 10) catch {
        writeLine("usb-xhci-bus: malformed controller device id '{s}'\n", .{argument});
        return;
    };

    if (!device.claim(controller_id)) {
        writeLine("usb-xhci-bus: unable to claim controller device {d}\n", .{controller_id});
        return;
    }

    // Fetch our own descriptor back for the controller's resources.
    const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
        _ = runtime.system.write("usb-xhci-bus: out of memory\n");
        return;
    };
    const total = device.enumerate(buffer);
    const descriptor = for (buffer[0..@min(total, buffer.len)]) |d| {
        if (d.id == controller_id) break d;
    } else {
        writeLine("usb-xhci-bus: device {d} not in the device tree\n", .{controller_id});
        return;
    };

    // The controller's operational registers live behind BAR0, enumerated as the
    // device's first memory resource.
    const register_window = for (descriptor.resources[0..@intCast(descriptor.resource_count)]) |resource| {
        if (resource.kind == @intFromEnum(device.ResourceKind.memory)) break resource;
    } else {
        writeLine("usb-xhci-bus: controller device {d} has no MMIO window\n", .{controller_id});
        return;
    };
    writeLine("usb-xhci-bus: claimed controller device {d} (registers at 0x{x}, {d} bytes)\n", .{
        controller_id,
        register_window.start,
        register_window.len,
    });

    // Controller bring-up (map the window, reset, rings, port scan) is the next
    // increment; stay resident as the bus's supervisor in the meantime.
    while (true) runtime.system.sleep(1000);
}

pub const panic = runtime.panic;
comptime {
    _ = &runtime.start._start; // pull the runtime entry shim into the image
}