diff --git a/ac97/ac97.c b/ac97/ac97.c
index 405f3af..b9e2ef7 100644
--- a/ac97/ac97.c
+++ b/ac97/ac97.c
@@ -25,8 +25,8 @@
 #include "clib.h"
 
 
-uint8_t first = 1, silent = 0, bus = 0, dev, func;
-uint16_t i, this_ven_id, this_dev_id, io_base, alt_io_base;
+uint8_t first = 1, silent = 0, bus, dev, func;
+uint16_t i, io_base, alt_io_base;
 
 
 static void
@@ -177,7 +177,7 @@ audiopci_codec_write(uint8_t reg, uint16_t val)
 
 
 static void
-audiopci_probe()
+audiopci_probe(uint16_t dev_id)
 {
     uint8_t rev;
 
@@ -185,7 +185,7 @@ audiopci_probe()
     rev = pci_readb(bus, dev, func, 0x08);
 
     /* Print controller information. */
-    printf("Found AudioPCI %04X revision %02X at bus %02X device %02X function %d\n", this_dev_id, rev, bus, dev, func);
+    printf("Found AudioPCI %04X revision %02X at bus %02X device %02X function %d\n", dev_id, rev, bus, dev, func);
     printf("Subsystem ID [%04X:%04X]\n", pci_readw(bus, dev, func, 0x2c), pci_readw(bus, dev, func, 0x2e));
 
     /* Get I/O BAR. */
@@ -266,14 +266,14 @@ via_codec_write(uint8_t reg, uint16_t val)
 
 
 static void
-via_probe()
+via_probe(uint16_t dev_id)
 {
     uint8_t rev, base_rev, is8233;
 
     /* Print controller information. */
     rev = pci_readb(bus, dev, func, 0x08);
     base_rev = pci_readb(bus, dev, 0, 0x08);
-    printf("Found VIA %04X revision %02X (base %02X) at bus %02X device %02X function %d\n", this_dev_id, rev, base_rev, bus, dev, func);
+    printf("Found VIA %04X revision %02X (base %02X) at bus %02X device %02X function %d\n", dev_id, rev, base_rev, bus, dev, func);
 
     /* Get SGD I/O BAR. */
     io_base = pci_get_io_bar(bus, dev, func, 0x10, 256, "SGD");
@@ -294,7 +294,7 @@ via_probe()
     printf("done.\n");
 
     /* Test Codec Shadow I/O BAR on 686. */
-    if (this_dev_id == 0x3058) {
+    if (dev_id == 0x3058) {
 	alt_io_base = pci_get_io_bar(bus, dev, func, 0x1c, 256, "Codec Shadow");
 
 	/* Perform tests if the BAR is set. */
@@ -364,13 +364,13 @@ intel_codec_write(uint8_t reg, uint16_t val)
 
 
 static void
-intel_probe()
+intel_probe(uint16_t dev_id)
 {
     uint8_t rev;
 
     /* Print controller information. */
     rev = pci_readb(bus, dev, func, 0x08);
-    printf("Found Intel %04X revision %02X at bus %02X device %02X function %d\n", this_dev_id, rev, bus, dev, func);
+    printf("Found Intel %04X revision %02X at bus %02X device %02X function %d\n", dev_id, rev, bus, dev, func);
 
     /* Get Mixer I/O BAR. */
     io_base = pci_get_io_bar(bus, dev, func, 0x10, 256, "Mixer");
@@ -416,83 +416,22 @@ print_spacer()
 
 
 static void
-scan_bus()
+pci_scan_callback(uint8_t this_bus, uint8_t this_dev, uint8_t this_func,
+		  uint16_t ven_id, uint16_t dev_id)
 {
-    uint8_t header_type, saved_bus, saved_dev, saved_func;
-    multi_t dev_id;
+    bus = this_bus;
+    dev = this_dev;
+    func = this_func;
 
-    /* Iterate through devices. */
-    for (dev = 0; dev < pci_device_count; dev++) {
-	/* Iterate through functions. */
-	for (func = 0; func < 8; func++) {
-		/* Read vendor/device ID. */
-#ifdef DEBUG
-		if ((bus < DEBUG) && (dev <= bus) && (func == 0)) {
-			dev_id.u16[0] = rand();
-			dev_id.u16[1] = rand();
-		} else {
-			dev_id.u32 = 0xffffffff;
-		}
-#else
-		dev_id.u32 = pci_readl(bus, dev, func, 0x00);
-#endif
-
-		/* Probe a valid ID. */
-		if (dev_id.u32 && (dev_id.u32 != 0xffffffff)) {
-			this_ven_id = dev_id.u16[0];
-			this_dev_id = dev_id.u16[1];
-			if ((this_ven_id == 0x1274) && (this_dev_id != 0x5000)) {
-				print_spacer();
-				audiopci_probe();
-			} else if ((this_ven_id == 0x1106) && ((this_dev_id == 0x3058) || (this_dev_id == 0x3059))) {
-				print_spacer();
-				via_probe();
-			} else if ((this_ven_id == 0x8086) && ((this_dev_id == 0x2415) || (this_dev_id == 0x2425) || (this_dev_id == 0x2445) || (this_dev_id == 0x2485) || (this_dev_id == 0x24c5) || (this_dev_id == 0x24d5) || (this_dev_id == 0x25a6) || (this_dev_id == 0x266e) || (this_dev_id == 0x27de) || (this_dev_id == 0x7195))) {
-				print_spacer();
-				intel_probe();
-			}
-		} else {
-			/* Stop or move on to the next function if there's nothing here. */
-			if (func)
-				continue;
-			else
-				break;
-		}
-
-		/* Read header type. */
-#ifdef DEBUG
-		header_type = (bus < (DEBUG - 1)) ? 0x01 : 0x00;
-#else
-		header_type = pci_readb(bus, dev, func, 0x0e);
-#endif
-
-		/* If this is a bridge, mark that we should probe its bus. */
-		if (header_type & 0x7f) {
-			/* Save current state. */
-			saved_bus = bus;
-			saved_dev = dev;
-			saved_func = func;
-
-			/* Read bus numbers. */
-#ifdef DEBUG
-			bus = bus + 1;
-#else
-			bus = pci_readb(bus, dev, func, 0x19);
-#endif
-
-			/* Scan the secondary bus. */
-			scan_bus();
-
-			/* Restore saved state. */
-			bus = saved_bus;
-			dev = saved_dev;
-			func = saved_func;
-		}
-
-		/* If we're at the first function, stop if this is not a multi-function device. */
-		if ((func == 0) && !(header_type & 0x80))
-			break;
-	}
+    if ((ven_id == 0x1274) && (dev_id != 0x5000)) {
+	print_spacer();
+	audiopci_probe(dev_id);
+    } else if ((ven_id == 0x1106) && ((dev_id == 0x3058) || (dev_id == 0x3059))) {
+	print_spacer();
+	via_probe(dev_id);
+    } else if ((ven_id == 0x8086) && ((dev_id == 0x2415) || (dev_id == 0x2425) || (dev_id == 0x2445) || (dev_id == 0x2485) || (dev_id == 0x24c5) || (dev_id == 0x24d5) || (dev_id == 0x25a6) || (dev_id == 0x266e) || (dev_id == 0x27de) || (dev_id == 0x7195))) {
+	print_spacer();
+	intel_probe(dev_id);
     }
 }
 
@@ -501,8 +440,6 @@ int
 main(int argc, char **argv)
 {
     uint8_t dev, func;
-    uint16_t ven_id, dev_id;
-    uint32_t cf8;
 
     /* Disable stdout buffering. */
     term_unbuffer_stdout();
@@ -516,7 +453,7 @@ main(int argc, char **argv)
 	silent = 1;
 
     /* Scan PCI bus 0. */
-    scan_bus();
+    pci_scan_bus(0, pci_scan_callback);
 
     return 0;
 }
diff --git a/clib/clib.c b/clib/clib.c
index da72eb5..cba8924 100644
--- a/clib/clib.c
+++ b/clib/clib.c
@@ -326,7 +326,7 @@ io_find_range(uint16_t size)
 }
 
 
-/* PCI I/O functions. */
+/* PCI functions. */
 uint32_t
 pci_cf8(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg)
 {
@@ -592,3 +592,63 @@ pci_writel(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg, uint32_t val)
 		break;
     }
 }
+
+
+void
+pci_scan_bus(uint8_t bus,
+	     void (*callback)(uint8_t bus, uint8_t dev, uint8_t func,
+			      uint16_t ven_id, uint16_t dev_id))
+{
+    uint8_t dev, func, header_type;
+    multi_t dev_id;
+
+    /* Iterate through devices. */
+    for (dev = 0; dev < pci_device_count; dev++) {
+	/* Iterate through functions. */
+	for (func = 0; func < 8; func++) {
+		/* Read vendor/device ID. */
+#ifdef DEBUG
+		if ((bus < DEBUG) && (dev <= bus) && (func == 0)) {
+			dev_id.u16[0] = rand();
+			dev_id.u16[1] = rand();
+		} else {
+			dev_id.u32 = 0xffffffff;
+		}
+#else
+		dev_id.u32 = pci_readl(bus, dev, func, 0x00);
+#endif
+
+		/* Callback if this is a valid ID. */
+		if (dev_id.u32 && (dev_id.u32 != 0xffffffff)) {
+			callback(bus, dev, func, dev_id.u16[0], dev_id.u16[1]);
+		} else {
+			/* Stop or move on to the next function if there's nothing here. */
+			if (func)
+				continue;
+			else
+				break;
+		}
+
+		/* Read header type. */
+#ifdef DEBUG
+		header_type = (bus < (DEBUG - 1)) ? 0x01 : 0x00;
+#else
+		header_type = pci_readb(bus, dev, func, 0x0e);
+#endif
+
+		/* If this is a bridge, mark that we should probe its bus. */
+		if (header_type & 0x7f) {
+			/* Scan the secondary bus. */
+#ifdef DEBUG
+			pci_scan_bus(bus + 1, callback);
+#else
+			pci_scan_bus(pci_readb(bus, dev, func, 0x19), callback);
+#endif
+		}
+
+		/* If we're at the first function, stop if this is not a multi-function device. */
+		if ((func == 0) && !(header_type & 0x80))
+			break;
+	}
+    }
+}
diff --git a/clib/clib.h b/clib/clib.h
index c92f49a..55afe0e 100644
--- a/clib/clib.h
+++ b/clib/clib.h
@@ -121,7 +121,7 @@ extern void	outl(uint16_t port, uint32_t data);
 #endif
 extern uint16_t	io_find_range(uint16_t size);
 
-/* PCI I/O functions. */
+/* PCI functions. */
 extern uint32_t	pci_cf8(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg);
 extern uint16_t	pci_get_io_bar(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg, uint16_t size, const char *name);
 extern int	pci_init();
@@ -131,5 +131,8 @@ extern uint32_t	pci_readl(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg);
 extern void	pci_writeb(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg, uint8_t val);
 extern void	pci_writew(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg, uint16_t val);
 extern void	pci_writel(uint8_t bus, uint8_t dev, uint8_t func, uint8_t reg, uint32_t val);
+extern void	pci_scan_bus(uint8_t bus,
+			     void (*callback)(uint8_t bus, uint8_t dev, uint8_t func,
+					      uint16_t ven_id, uint16_t dev_id));
 
 #endif