update comment according to the new DOM

git-svn-id: svn://svn.coreboot.org/coreboot/trunk@1799 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

5 files changed, 109 insertions, 74 deletions

diff --git a/src/devices/device.c b/src/devices/device.c
index 033f41d2ca..87e627d52c 100644
--- a/src/devices/device.c
+++ b/src/devices/device.c
@@ -376,13 +376,14 @@ static void allocate_vga_resource(void)
 	struct bus *bus;
 	bus = 0;
 	vga = 0;
-	for(dev = all_devices; dev; dev = dev->next) {
+	for (dev = all_devices; dev; dev = dev->next) {
 		if (((dev->class >> 16) == PCI_BASE_CLASS_DISPLAY) &&
-			((dev->class >> 8) != PCI_CLASS_DISPLAY_OTHER)) 
-		{
+		    ((dev->class >> 8) != PCI_CLASS_DISPLAY_OTHER)) {
 			if (!vga) {
 				printk_debug("Allocating VGA resource %s\n",
-					dev_path(dev));
+					     dev_path(dev));
+				printk_debug("parent of the vga device %s\n",
+					     dev_path(dev->bus->dev));
 				vga = dev;
 			}
 			if (vga == dev) {
@@ -398,19 +399,28 @@ static void allocate_vga_resource(void)
 		bus = vga->bus;
 	}
 	/* Now walk up the bridges setting the VGA enable */
-	while(bus) {
+	while (bus) {
+		printk_info("Enabling VGA forward on bus connect to %s\n",
+			    dev_path(bus->dev));
 		bus->bridge_ctrl |= PCI_BRIDGE_CTL_VGA;
 		bus = (bus == bus->dev->bus)? 0 : bus->dev->bus;
 	} 
 }
 
 
-/** Assign the computed resources to the bridges and devices on the bus.
- * Recurse to any bridges found on this bus first. Then do the devices
- * on this bus.
- * 
+/**
+ * @brief  Assign the computed resources to the devices on the bus.
+ *
  * @param bus Pointer to the structure for this bus
- */ 
+ *
+ * Use the device specific set_resources method to store the computed
+ * resources to hardware. For bridge devices, the set_resources() method
+ * has to recurse into every down stream buses.
+ *
+ * Mutual recursion:
+ *	assign_resources() -> device_operation::set_resources()
+ *	device_operation::set_resources() -> assign_resources()
+ */
 void assign_resources(struct bus *bus)
 {
 	struct device *curdev;
@@ -418,7 +428,7 @@ void assign_resources(struct bus *bus)
 	printk_spew("%s assign_resources, bus %d link: %d\n", 
 		dev_path(bus->dev), bus->secondary, bus->link);
 
-	for(curdev = bus->children; curdev; curdev = curdev->sibling) {
+	for (curdev = bus->children; curdev; curdev = curdev->sibling) {
 		if (!curdev->enabled || !curdev->resources) {
 			continue;
 		}
@@ -443,10 +453,13 @@ void assign_resources(struct bus *bus)
  *
  * The parent's resources should be enabled first to avoid having enabling
  * order problem. This is done by calling the parent's enable_resources()
- * method and let that method to call it's children's enable_resoruces() via
- * enable_childrens_resources().
+ * method and let that method to call it's children's enable_resoruces()
+ * method via the (global) enable_childrens_resources().
  *
  * Indirect mutual recursion:
+ *	enable_resources() -> device_operations::enable_resource()
+ *	device_operations::enable_resource() -> enable_children_resources()
+ *	enable_children_resources() -> enable_resources()
  */
 void enable_resources(struct device *dev)
 {
@@ -461,16 +474,25 @@ void enable_resources(struct device *dev)
 }
 
 /**
- * @brief Determine the existence of dynamic devices and construct dynamic
+ * @brief Determine the existence of devices and extend the device tree.
+ *
+ * Most of the devices in the system are listed in the mainboard Config.lb
+ * file. The device structures for these devices are generated at compile
+ * time by the config tool and are organized into the device tree. This
+ * function determines if the devices created at compile time actually exist
+ * in the physical system.
+ *
+ * For devices in the physical system but not listed in the Config.lb file,
+ * the device structures have to be created at run time and attached to the
  * device tree.
  *
- * Start from the root device 'dev_root', scan the buses in the system
- * recursively, build the dynamic device tree according to the result
- * of the probe.
+ * This function starts from the root device 'dev_root', scan the buses in
+ * the system recursively, modify the device tree according to the result of
+ * the probe.
  *
  * This function has no idea how to scan and probe buses and devices at all.
  * It depends on the bus/device specific scan_bus() method to do it. The
- * scan_bus() function also has to create the device structure and attach
+ * scan_bus() method also has to create the device structure and attach
  * it to the device tree. 
  */
 void dev_enumerate(void)
@@ -490,12 +512,13 @@ void dev_enumerate(void)
 	printk_info("done\n");
 }
 
-
 /**
  * @brief Configure devices on the devices tree.
  * 
- * Starting at the root of the dynamic device tree, travel recursively,
- * and compute resources needed by each device and allocate them.
+ * Starting at the root of the device tree, travel it recursively in two
+ * passes. In the first pass, we compute and allocate resources (ranges)
+ * requried by each device. In the second pass, the resources ranges are
+ * relocated to their final position and stored to the hardware.
  *
  * I/O resources start at DEVICE_IO_START and grow upward. MEM resources start
  * at DEVICE_MEM_START and grow downward.
@@ -519,7 +542,10 @@ void dev_configure(void)
 		printk_err("dev_root missing set_resources\n");
 		return;
 	}
+
+	printk_info("Reading resources...\n");
 	root->ops->read_resources(root);
+	printk_info("Done\n");
 
 	/* Get the resources */
 	io  = &root->resource[0];
@@ -539,8 +565,9 @@ void dev_configure(void)
 	allocate_vga_resource(); 
 
 	/* Store the computed resource allocations into device registers ... */
+	printk_info("Setting resources...\n");
 	root->ops->set_resources(root);
-
+	printk_info("Done\n");
 #if 0
 	mem->flags |= IORESOURCE_STORED;
 	report_resource_stored(root, mem, "");
@@ -569,14 +596,15 @@ void dev_enable(void)
  * @brief Initialize all devices in the global device list.
  *
  * Starting at the first device on the global device link list,
- * walk the list and call a driver to do device specific setup.
+ * walk the list and call the device's init() method to do deivce
+ * specific setup.
  */
 void dev_initialize(void)
 {
 	struct device *dev;
 
 	printk_info("Initializing devices...\n");
-	for(dev = all_devices; dev; dev = dev->next) {
+	for (dev = all_devices; dev; dev = dev->next) {
 		if (dev->enabled && !dev->initialized && 
 			dev->ops && dev->ops->init) 
 		{
diff --git a/src/devices/pci_device.c b/src/devices/pci_device.c
index bd5e2775fe..a32c3a675f 100644
--- a/src/devices/pci_device.c
+++ b/src/devices/pci_device.c
@@ -569,9 +569,9 @@ static void set_pci_ops(struct device *dev)
 	/* Look through the list of setup drivers and find one for
 	 * this pci device 
 	 */
-	for(driver = &pci_drivers[0]; driver != &epci_drivers[0]; driver++) {
+	for (driver = &pci_drivers[0]; driver != &epci_drivers[0]; driver++) {
 		if ((driver->vendor == dev->vendor) &&
-			(driver->device == dev->device)) 
+		    (driver->device == dev->device)) 
 		{
 			dev->ops = driver->ops;
 			printk_debug("%s [%04x/%04x] %sops\n", 
@@ -665,9 +665,6 @@ static struct device *pci_scan_get_dev(struct device **list, unsigned int devfn)
  * Determine the existence of devices and bridges on a PCI bus. If there are
  * bridges on the bus, recursively scan the buses behind the bridges.
  *
- * This function is the default scan_bus() method for the root device
- * 'dev_root'.
- *
  * @param bus pointer to the bus structure
  * @param min_devfn minimum devfn to look at in the scan usually 0x00
  * @param max_devfn maximum devfn to look at in the scan usually 0xff
@@ -709,8 +706,8 @@ unsigned int pci_scan_bus(struct bus *bus,
 			dummy.path.u.pci.devfn = devfn;
 			id = pci_read_config32(&dummy, PCI_VENDOR_ID);
 			/* some broken boards return 0 if a slot is empty: */
-			if (	(id == 0xffffffff) || (id == 0x00000000) || 
-				(id == 0x0000ffff) || (id == 0xffff0000))
+			if ((id == 0xffffffff) || (id == 0x00000000) || 
+			    (id == 0x0000ffff) || (id == 0xffff0000))
 			{
 				printk_spew("PCI: devfn 0x%x, bad id 0x%x\n", devfn, id);
 				if (PCI_FUNC(devfn) == 0x00) {
@@ -753,7 +750,7 @@ unsigned int pci_scan_bus(struct bus *bus,
 			 * that may not always show up.
 			 */
 			if (id == 0xffffffff || id == 0x00000000 ||
-				id == 0x0000ffff || id == 0xffff0000) 
+			    id == 0x0000ffff || id == 0xffff0000) 
 			{
 				if (dev->enabled) {
 					printk_info("Disabling static device: %s\n",
@@ -816,10 +813,10 @@ unsigned int pci_scan_bus(struct bus *bus,
 	/* For all children that implement scan_bus (i.e. bridges)
 	 * scan the bus behind that child.
 	 */
-	for(child = bus->children; child; child = child->sibling) {
+	for (child = bus->children; child; child = child->sibling) {
 		if (!child->enabled ||
-			!child->ops || 
-			!child->ops->scan_bus) 
+		    !child->ops || 
+		    !child->ops->scan_bus) 
 		{
 			continue;
 		}
diff --git a/src/devices/root_device.c b/src/devices/root_device.c
index 897a5a3bbf..a02fe7a060 100644
--- a/src/devices/root_device.c
+++ b/src/devices/root_device.c
@@ -35,7 +35,8 @@ void root_dev_read_resources(device_t root)
 }
 
 /**
- * Write the resources for the root device,
+ * @brief Write the resources for the root device
+ *
  * and every device under it which are all of the devices.
  * @param root Pointer to the device structure for the system root device
  */
@@ -44,10 +45,10 @@ void root_dev_set_resources(device_t root)
 	struct bus *bus;
 
 	bus = &root->link[0];
-	compute_allocate_resource(bus,
-		&root->resource[0], IORESOURCE_IO, IORESOURCE_IO);
-	compute_allocate_resource(bus, 
-		&root->resource[1], IORESOURCE_MEM, IORESOURCE_MEM);
+	compute_allocate_resource(bus, &root->resource[0],
+				  IORESOURCE_IO, IORESOURCE_IO);
+	compute_allocate_resource(bus, &root->resource[1],
+				  IORESOURCE_MEM, IORESOURCE_MEM);
 	assign_resources(bus);
 }
 
@@ -56,26 +57,32 @@ void root_dev_set_resources(device_t root)
  *
  * The enumeration of certain buses is purely static. The existence of
  * devices on those buses can be completely determined at compile time
- * by the config file. Typical expamles are the 'PNP' devices on a legacy
- * ISA/LPC bus. There is no need of probing of any kind, the only thing
- * we have to do is to walk through the bus and enable or disable devices
- * as indicated in the config file.
+ * and is specified in the config file. Typical exapmles are the 'PNP'
+ * devices on a legacy ISA/LPC bus. There is no need of probing of any
+ * kind, the only thing we have to do is to walk through the bus and
+ * enable or disable devices as indicated in the config file.
  *
- * This function is the default scan_bus() method for LPC bridges.
+ * On the other hand, some devices are virtual and their existence is
+ * artificial. They can not be probed at run time. One example is the
+ * debug device. Those virtual devices have to be listed in the config
+ * file under some static bus in order to be enumerated at run time.
  *
- * @param root Pointer to the device structure for the system root device
- * @param max  Maximum bus number allowed in the system.
- * @return Largest bus number used.
+ * This function is the default scan_bus() method for the root device and
+ * LPC bridges.
+ *
+ * @param root Pointer to the root device which the static buses are attached
+ * @param max  Maximum bus number currently used before scanning.
+ * @return Largest bus number used after scanning.
  */
-unsigned int scan_static_bus(device_t bus, unsigned int max)
+unsigned int scan_static_bus(device_t root, unsigned int max)
 {
 	device_t child;
 	unsigned link;
-	
-	printk_spew("%s for %s\n", __func__, dev_path(bus));
 
-	for(link = 0; link < bus->links; link++) {
-		for(child = bus->link[link].children; child; child = child->sibling) {
+	printk_spew("%s for %s\n", __func__, dev_path(root));
+
+	for (link = 0; link < root->links; link++) {
+		for (child = root->link[link].children; child; child = child->sibling) {
 			if (child->chip_ops && child->chip_ops->enable_dev) {
 				child->chip_ops->enable_dev(child);
 			}
@@ -87,8 +94,8 @@ unsigned int scan_static_bus(device_t bus, unsigned int max)
 				child->enabled?"enabled": "disabled");
 		}
 	}
-	for(link = 0; link < bus->links; link++) {
-		for(child = bus->link[link].children; child; child = child->sibling) {
+	for (link = 0; link < root->links; link++) {
+		for (child = root->link[link].children; child; child = child->sibling) {
 			if (!child->ops || !child->ops->scan_bus)
 				continue;
 			printk_spew("%s scanning...\n", dev_path(child));
@@ -96,7 +103,7 @@ unsigned int scan_static_bus(device_t bus, unsigned int max)
 		}
 	}
 
-	printk_spew("%s done\n", __func__);
+	printk_spew("%s for  %s done\n", __func__, dev_path(root));
 
 	return max;
 }
@@ -106,17 +113,20 @@ unsigned int scan_static_bus(device_t bus, unsigned int max)
  *
  * @param dev the device whos children's resources are to be enabled
  *
- * This function is call by the enable_resource() indirectly via the
- * enable_resources() method of devices.
+ * This function is call by the global enable_resources() indirectly via the
+ * device_operation::enable_resources() method of devices.
  *
  * Indirect mutual recursion:
+ *	enable_childrens_resources() -> enable_resources()
+ *	enable_resources() -> device_operation::enable_resources()
+ *	device_operation::enable_resources() -> enable_children_resources()
  */
 void enable_childrens_resources(device_t dev)
 {
 	unsigned link;
-	for(link = 0; link < dev->links; link++) {
+	for (link = 0; link < dev->links; link++) {
 		device_t child;
-		for(child = dev->link[link].children; child; child = child->sibling) {
+		for (child = dev->link[link].children; child; child = child->sibling) {
 			enable_resources(child);
 		}
 	}
@@ -131,12 +141,9 @@ void root_dev_enable_resources(device_t dev)
  * @brief Scan root bus for generic systems
  *
  * @param root The root device structure
- * @param max The current bus number scanned so fat, usually 0x00
+ * @param max The current bus number scanned so far, usually 0x00
  *
- * This function is the default scan_bus() method of the dynamic root device.
- * The bus heirachy is rooted at the host/northbridge. The northbridge of a
- * generic PCI bus system is at Bus 0, Dev 0, Fun 0 so we scan the whole PCI
- * buses from there. 
+ * This function is the default scan_bus() method of the root device.
  */
 unsigned int root_dev_scan_bus(device_t root, unsigned int max)
 {
@@ -150,11 +157,9 @@ void root_dev_init(device_t root)
 /**
  * @brief Default device operation for root device
  *
- * This is the default device operation for root devices in PCI based systems.
- * These operations should be fully usable as is.  However the 
- * chip_operations::dev_enable of a motherboard can override this if you
- * want non-default behavior.  Currently src/mainboard/arima/hdama/mainbaord.c
- * does this for debugging purposes.
+ * This is the default device operation for root devices. These operations
+ * should be fully usable as is.  However the chip_operations::enable_dev()
+ * of a motherboard can override this if you want non-default behavior.
  */
 struct device_operations default_dev_ops_root = {
 	.read_resources   = root_dev_read_resources,
@@ -165,9 +170,9 @@ struct device_operations default_dev_ops_root = {
 };
 
 /**
- * @brief The root of dynamic device tree.
+ * @brief The root of device tree.
  *
- * This is the root of the dynamic device tree. A PCI tree always has 
- * one bus, bus 0. Bus 0 contains devices and bridges. 
+ * This is the root of the device tree. The device tree is defined in the
+ * static.c file and is generated by config tool during compile time.
  */
 extern struct device dev_root;
diff --git a/src/include/device/device.h b/src/include/device/device.h
index db91fcc1ef..167a518f2a 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -57,7 +57,8 @@ struct bus {
  */
 
 struct device {
-	struct bus *	bus;		/* bus this device is on */
+	struct bus *	bus;		/* bus this device is on, for bridge
+					 * devices, it is the up stream bus */
 	device_t	sibling;	/* next device on this bus */
 	device_t	next;		/* chain of all devices */
 
@@ -79,7 +80,10 @@ struct device {
 	struct resource resource[MAX_RESOURCES];
 	unsigned int resources;
 
+	/* link are (down sream) buses attached to the device, usually a leaf
+	 * device with no child have 0 bus attached and a bridge has 1 bus */
 	struct bus link[MAX_LINKS];
+	/* number of buses attached to the device */
 	unsigned int links;
 
 	unsigned long rom_address;
diff --git a/src/include/device/pci.h b/src/include/device/pci.h
index 2c9797fa6c..0ee31f1cb9 100644
--- a/src/include/device/pci.h
+++ b/src/include/device/pci.h
@@ -23,6 +23,7 @@
 
 /* Common pci operations without a standard interface */
 struct pci_operations {
+	/* set the Subsystem IDs for the PCI device */
 	void (*set_subsystem)(device_t dev, unsigned vendor, unsigned device);
 };