PCI: add struct pci_host_bridge and a list of all bridges found

This adds a list of all PCI host bridges we find and a way to look up
the host bridge from a pci_dev.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

2 files changed, 39 insertions, 5 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e4c0d1c6324d..3a30023a123c 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -15,6 +15,8 @@
 #define CARDBUS_LATENCY_TIMER   176     /* secondary latency timer */
 #define CARDBUS_RESERVE_BUSNR   3
 
+static LIST_HEAD(pci_host_bridges);
+
 /* Ugh.  Need to stop exporting this to modules. */
 LIST_HEAD(pci_root_buses);
 EXPORT_SYMBOL(pci_root_buses);
@@ -42,6 +44,23 @@ int no_pci_devices(void)
 }
 EXPORT_SYMBOL(no_pci_devices);
 
+static struct pci_host_bridge *pci_host_bridge(struct pci_dev *dev)
+{
+        struct pci_bus *bus;
+        struct pci_host_bridge *bridge;
+
+        bus = dev->bus;
+        while (bus->parent)
+                bus = bus->parent;
+
+        list_for_each_entry(bridge, &pci_host_bridges, list) {
+                if (bridge->bus == bus)
+                        return bridge;
+        }
+
+        return NULL;
+}
+
 /*
  * PCI Bus Class
  */
@@ -1544,20 +1563,23 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
                 struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {
         int error, i;
+        struct pci_host_bridge *bridge;
         struct pci_bus *b, *b2;
         struct device *dev;
         struct pci_bus_resource *bus_res, *n;
         struct resource *res;
 
+        bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
+        if (!bridge)
+                return NULL;
+
         b = pci_alloc_bus();
         if (!b)
-                return NULL;
+                goto err_bus;
 
         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-        if (!dev) {
-                kfree(b);
-                return NULL;
-        }
+        if (!dev)
+                goto err_dev;
 
         b->sysdata = sysdata;
         b->ops = ops;
@@ -1594,6 +1616,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 
         b->number = b->secondary = bus;
 
+        bridge->bus = b;
+
         /* Add initial resources to the bus */
         list_for_each_entry_safe(bus_res, n, resources, list)
                 list_move_tail(&bus_res->list, &b->resources);
@@ -1609,6 +1633,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
         }
 
         down_write(&pci_bus_sem);
+        list_add_tail(&bridge->list, &pci_host_bridges);
         list_add_tail(&b->node, &pci_root_buses);
         up_write(&pci_bus_sem);
 
@@ -1618,11 +1643,15 @@ class_dev_reg_err:
         device_unregister(dev);
 dev_reg_err:
         down_write(&pci_bus_sem);
+        list_del(&bridge->list);
         list_del(&b->node);
         up_write(&pci_bus_sem);
 err_out:
         kfree(dev);
+err_dev:
         kfree(b);
+err_bus:
+        kfree(bridge);
         return NULL;
 }
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index bcaa51ca7858..2c946b3bbf77 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -368,6 +368,11 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
         return (pdev->error_state != pci_channel_io_normal);
 }
 
+struct pci_host_bridge {
+        struct list_head list;
+        struct pci_bus *bus;            /* root bus */
+};
+
 /*
  * The first PCI_BRIDGE_RESOURCE_NUM PCI bus resources (those that correspond
  * to P2P or CardBus bridge windows) go in a table.  Additional ones (for