Scan for PCI devices

src/hos/cpu.d

@@ -24,3 +24,23 @@ ulong read_cr4()
 {
     return __asm!ulong("mov %cr4, %rax", "={rax}");
 }
+
+ushort in16(ushort ioaddr)
+{
+    return __asm!ushort("inw %dx, %ax", "={ax},{dx}", ioaddr);
+}
+
+ulong in32(ushort ioaddr)
+{
+    return __asm!ulong("inl %dx, %eax", "={eax},{dx}", ioaddr);
+}
+
+void out16(ushort ioaddr, ushort v)
+{
+    __asm("outw %ax, %dx", "{dx},{ax}", ioaddr, v);
+}
+
+void out32(ushort ioaddr, ulong v)
+{
+    __asm("outl %eax, %dx", "{dx},{eax}", ioaddr, v);
+}

src/hulk/hulk.d

@@ -12,6 +12,7 @@ import hulk.kfont;
 import hulk.klog;
 import hulk.hurl;
 import hulk.hippo;
+import hulk.pci;
 
 extern extern(C) __gshared ubyte _hulk_total_size;
 
@@ -38,6 +39,7 @@ void hulk_start()
     klog.writefln("Welcome to HULK, the HOS UltraLight Kernel!");
 
     hippo.initialize(&hulk_header);
+    pci.initialize();
 
     for (;;)
     {

src/hulk/pci.d

@@ -0,0 +1,48 @@
+module hulk.pci;
+
+import hos.cpu;
+import hulk.klog;
+
+struct pci
+{
+    /* IO address for PCI configuration address. */
+    enum IO_ADDR_CONFIG_ADDRESS = 0xCF8u;
+
+    /* IO address for PCI configuration data. */
+    enum IO_ADDR_CONFIG_DATA = 0xCFCu;
+
+    private static ulong read_config_register(ulong bus_id, ulong device_id, ulong register_id)
+    {
+        ulong addr = 0x8000_0000u | (bus_id << 16u) | (device_id << 11u) | (register_id << 2u);
+        out32(IO_ADDR_CONFIG_ADDRESS, addr);
+        return in32(IO_ADDR_CONFIG_DATA);
+    }
+
+    private static void scan(ulong bus_id, ulong device_id)
+    {
+        ulong reg0 = read_config_register(bus_id, device_id, 0u);
+        if (reg0 != 0xFFFFFFFFu)
+        {
+            ulong reg2 = read_config_register(bus_id, device_id, 2u);
+            klog.writefln("Found PCI device %04x:%04x (%02x:%02x:%02x) at %02u:%02u",
+                    (reg0 & 0xFFFFu), (reg0 >> 16u),
+                    (reg2 >> 24u) & 0xFFu,
+                    (reg2 >> 16u) & 0xFFu,
+                    (reg2 >> 8u) & 0xFFu,
+                    bus_id, device_id);
+        }
+    }
+
+    public static void initialize()
+    {
+        klog.writefln("Scanning PCI devices...");
+        for (ulong bus_id = 0u; bus_id < 256u; bus_id++)
+        {
+            for (ulong device_id = 0u; device_id < 32u; device_id++)
+            {
+                scan(bus_id, device_id);
+            }
+        }
+        klog.writefln("PCI scan complete.");
+    }
+}