Finishing PS/2 bus driver

system/services/device-manager/device-manager.zig

@@ -12,19 +12,34 @@
 //! HPET, decides `hpet` serves it, and brings that driver all the way up. (The
 //! kernel still auto-spawns the whole initial-ramdisk at boot; increment 3 removes
 //! that redundancy so the manager is the sole owner of driver spawning.)
-
+const std = @import("std");
 const runtime = @import("runtime");
 const device = runtime.device;
+const system = runtime.system;
 
-/// The driver that serves each device class — the policy table. In a fuller system
+/// Format one whole log line and emit it in a single `debug_write`, so output
+/// from the drivers this manager starts (which run concurrently) can never land
+/// in the middle of it.
+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);
+}
+
+/// The driver that serves each device — the policy table. In a fuller system
 /// this comes from the drivers describing what they bind (or a manifest under
 /// /system/drivers); for now it is a small static map, which is enough to prove the
 /// manager reads the tree and decides. `null` = no driver for this class yet.
-fn driverFor(class: u64) ?[]const u8 {
-    if (class == @intFromEnum(device.DeviceClass.timer)) return "hpet"; // the HPET
+fn driverFor(d: device.DeviceDescriptor) ?[]const u8 {
+    // detect device via DeviceClass
+    if (d.class == @intFromEnum(device.DeviceClass.timer)) return "hpet";
+    // detect device via hid
+    const hid = d.hid[0..@intCast(d.hid_len)];
+    if (std.mem.eql(u8, hid, "PNP0303") or std.mem.eql(u8, hid, "PNP0F13")) return "ps2-bus";
+
     return null;
 }
 
+
 pub fn main() void {
     // Enumerate into a heap buffer (too big for the one-page user stack).
     const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
@@ -36,16 +51,16 @@ pub fn main() void {
 
     var matched: usize = 0;
     for (buffer[0..count]) |descriptor| {
-        const driver_name = driverFor(descriptor.class) orelse continue;
+        const driver_name = driverFor(descriptor) orelse continue;
         matched += 1;
-        if (runtime.system.spawn(driver_name) != null) {
-            _ = runtime.system.write("device-manager: spawned ");
-            _ = runtime.system.write(driver_name);
-            _ = runtime.system.write("\n");
+        if (!system.isProcessRunning(driver_name)) {
+            if (runtime.system.spawn(driver_name) != null) {
+                writeLine("device-manager: spawned {s}\n", .{driver_name});
+            } else {
+                writeLine("device-manager: failed to spawn {s}\n", .{driver_name});
+            }
         } else {
-            _ = runtime.system.write("device-manager: failed to spawn ");
-            _ = runtime.system.write(driver_name);
-            _ = runtime.system.write("\n");
+            writeLine("device-manager: already spawned {s}\n", .{driver_name});
         }
     }