Separate out bus-scanning and device-probing logic.

src/core/dev.c

@@ -2,6 +2,20 @@
 #include "stddef.h"
 #include "dev.h"
 
+/*
+ * Each driver specifies a name, the bus-scanning function
+ * (find_bus_boot_device) that it wants to use, a driver information
+ * structure (bus_driver) containing e.g. device IDs to be passed to
+ * find_bus_boot_device, and a probe function (probe) to be called
+ * whenever a suitable device is found.
+ *
+ * The generic device-probing code knows nothing about particular bus
+ * types; it simply passes the driver information structure
+ * (bus_driver) to the bus-scanning function (find_bus_boot_device),
+ * then passes the result of that function (if not NULL) to the probe
+ * function (probe).
+ */
+
 /* Defined by linker */
 extern struct boot_driver boot_drivers[];
 extern struct boot_driver boot_drivers_end[];
@@ -19,19 +33,30 @@ void print_drivers ( void ) {
 }
 
 /* Get the next available boot device */
-int probe ( struct dev *dev ) {
-	
+int find_boot_device ( struct dev *dev ) {
 	for ( ; boot_driver < boot_drivers_end ; boot_driver++ ) {
-		dev->name = "unknown";
-		if ( boot_driver->probe ( dev ) )
+		dev->driver = boot_driver;
+		dev->name = boot_driver->name;
+		DBG ( "Probing driver %s...\n", dev->name );
+		if (  boot_driver->find_bus_boot_device ( dev,
+						  boot_driver->bus_driver ) ) {
+			DBG ( "Found device %s (ID %hhx:%hx:%hx)\n",
+			      dev->name, dev->devid->bus_type,
+			      dev->devid->vendor_id, dev->devid->device_id );
 			return 1;
+		}
 	}
-	
+
 	/* No more boot devices found */
 	boot_driver = boot_drivers;
 	return 0;
 }
 
+/* Probe the boot device */
+int probe ( struct dev *dev ) {
+	return dev->driver->probe ( dev, dev->bus );
+}
+
 /* Disable a device */
 void disable ( struct dev *dev ) {
 	if ( dev->dev_op ) {

src/core/main.c

@@ -144,7 +144,7 @@ static int initialized;
 
 
 /* Global instance of the current boot device */
-DEV_BUS(struct {}, dev_bus);
+DEV_BUS(struct bus_device, dev_bus);
 struct dev dev = {
 	.bus = &dev_bus,
 };
@@ -181,8 +181,17 @@ int main ( void ) {
 	for ( ; ; disable ( &dev ), call_reset_fns() ) {
 
 		/* Get next boot device */
-		if ( ! probe ( &dev ) ) {
+		if ( ! find_boot_device ( &dev ) ) {
 			/* Reached end of device list */
+			printf ( "No more boot devices\n" );
+			continue;
+		}
+
+		/* Probe boot device */
+		if ( ! probe ( &dev ) ) {
+			/* Device found on bus, but probe failed */
+			printf ( "Probe failed on %s, trying next device\n",
+				 dev.name );
 			continue;
 		}
 		
@@ -192,12 +201,14 @@ int main ( void ) {
 		/* Load configuration (e.g. DHCP) */
 		if ( ! load_configuration ( &dev ) ) {
 			/* DHCP failed */
+			printf ( "Could not configure device %s\n", dev.name );
 			continue;
 		}
 
 		/* Load image */
 		if ( ! load ( &dev ) )
 			/* Load failed */
+			printf ( "Could not boot from device %s\n", dev.name );
 			continue;
 	}
 

src/include/dev.h

@@ -23,11 +23,12 @@ struct dev {
 	struct dev_operations *dev_op;
 	const char *name;
 	struct dev_id	devid;	/* device ID string (sent to DHCP server) */
+	struct boot_driver *driver; /* driver being used for boot */
 	/* Pointer to bus information for device.  Whatever sets up
 	 * the struct dev must make sure that this points to a buffer
 	 * large enough for the required struct <bus>_device.
 	 */
-	void *bus;
+	struct bus_device *bus;
 	/* All possible device types */
 	union {
 		struct nic	nic;
@@ -49,20 +50,33 @@ struct dev_operations {
 	int ( *load ) ( struct dev * );
 };
 
+/*
+ * Table to describe a bootable device driver.  See comments in dev.c
+ * for an explanation.
+ *
+ */
+struct bus_device {};
+struct bus_driver {};
 struct boot_driver {
 	char *name;
-	int (*probe) ( struct dev * );
+	struct bus_device * ( *find_bus_boot_device ) ( struct dev *dev,
+						   struct bus_driver *driver );
+	struct bus_driver *bus_driver;
+	int ( *probe ) ( struct dev *dev, struct bus_device *bus_device );
 };
 
-#define BOOT_DRIVER( driver_name, probe_func )				      \
+#define BOOT_DRIVER( _name, _find_bus_boot_device, _bus_driver,	_probe )      \
 	static struct boot_driver boot_driver_ ## probe_func		      \
 	    __attribute__ ((used,__section__(".boot_drivers"))) = {	      \
-		.name = driver_name,					      \
-		.probe = probe_func,					      \
+		.name = _name,						      \
+		.find_bus_boot_device = ( void * ) _find_bus_boot_device,     \
+		.bus_driver = ( void * ) _bus_driver,			      \
+		.probe = ( void * ) _probe,				      \
 	};
 
 /* Functions in dev.c */
 extern void print_drivers ( void );
+extern int find_boot_device ( struct dev *dev );
 extern int probe ( struct dev *dev );
 extern void disable ( struct dev *dev );
 static inline void print_info ( struct dev *dev ) {