firewire: reread config ROM when device reset the bus

When a device changes its configuration ROM, it announces this with a
bus reset.  firewire-core has to check which node initiated a bus reset
and whether any unit directories went away or were added on this node.

Tested with an IOI FWB-IDE01AB which has its link-on bit set if bus
power is available but does not respond to ROM read requests if self
power is off.  This implements
  - recognition of the units if self power is switched on after fw-core
    gave up the initial attempt to read the config ROM,
  - shutdown of the units when self power is switched off.

Also tested with a second PC running Linux/ieee1394.  When the eth1394
driver is inserted and removed on that node, fw-core now notices the
addition and removal of the IPv4 unit on the ieee1394 node.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-sbp2.c

@@ -153,6 +153,7 @@ struct sbp2_target {
 	struct list_head lu_list;
 
 	u64 management_agent_address;
+	u64 guid;
 	int directory_id;
 	int node_id;
 	int address_high;
@@ -1114,6 +1115,7 @@ static int sbp2_probe(struct device *dev)
 	kref_init(&tgt->kref);
 	INIT_LIST_HEAD(&tgt->lu_list);
 	tgt->bus_id = unit->device.bus_id;
+	tgt->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];
 
 	if (fw_device_enable_phys_dma(device) < 0)
 		goto fail_shost_put;
@@ -1571,16 +1573,14 @@ sbp2_sysfs_ieee1394_id_show(struct device *dev, struct device_attribute *attr,
 {
 	struct scsi_device *sdev = to_scsi_device(dev);
 	struct sbp2_logical_unit *lu;
-	struct fw_device *device;
 
 	if (!sdev)
 		return 0;
 
 	lu = sdev->hostdata;
-	device = fw_device(lu->tgt->unit->device.parent);
 
-	return sprintf(buf, "%08x%08x:%06x:%04x\n",
-			device->config_rom[3], device->config_rom[4],
+	return sprintf(buf, "%016llx:%06x:%04x\n",
+			(unsigned long long)lu->tgt->guid,
 			lu->tgt->directory_id, lu->lun);
 }