EISA/PCI: Fix bus res reference

Matthew found that 3.8.3 is having problems with an old (ancient)
PCI-to-EISA bridge, the Intel 82375. It worked with the 3.2 kernel.
He identified the 82375, but doesn't assign the struct resource *res
pointer inside the struct eisa_root_device, and panics.

pci_eisa_init() was using bus->resource[] directly instead of
pci_bus_resource_n().  The bus->resource[] array is a PCI-internal
implementation detail, and after commit 45ca9e97 (PCI: add helpers for
building PCI bus resource lists) and commit 0efd5aab (PCI: add struct
pci_host_bridge_window with CPU/bus address offset), bus->resource[] is not
used for PCI root buses any more.

The 82375 is a subtractive-decode PCI device, so handle it the same
way we handle PCI-PCI bridges in subtractive-decode mode in
pci_read_bridge_bases().

[bhelgaas: changelog]
Reported-by: Matthew Whitehead <mwhitehe@redhat.com>
Tested-by: Matthew Whitehead <mwhitehe@redhat.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v3.3+

diff --git a/drivers/eisa/pci_eisa.c b/drivers/eisa/pci_eisa.c
index cdae207..ef5c3ec 100644 (file)
--- a/drivers/eisa/pci_eisa.c
+++ b/drivers/eisa/pci_eisa.c
@@ -22,7 +22,8 @@ static struct eisa_root_device pci_eisa_root;
 static int __init pci_eisa_init(struct pci_dev *pdev,
                                const struct pci_device_id *ent)
 {
-       int rc;
+       int rc, i;
+       struct resource *res, *bus_res = NULL;
 
        if ((rc = pci_enable_device (pdev))) {
                printk (KERN_ERR "pci_eisa : Could not enable device %s\n",
@@ -30,9 +31,30 @@ static int __init pci_eisa_init(struct pci_dev *pdev,
                return rc;
        }
 
+       /*
+        * The Intel 82375 PCI-EISA bridge is a subtractive-decode PCI
+        * device, so the resources available on EISA are the same as those
+        * available on the 82375 bus.  This works the same as a PCI-PCI
+        * bridge in subtractive-decode mode (see pci_read_bridge_bases()).
+        * We assume other PCI-EISA bridges are similar.
+        *
+        * eisa_root_register() can only deal with a single io port resource,
+       *  so we use the first valid io port resource.
+        */
+       pci_bus_for_each_resource(pdev->bus, res, i)
+               if (res && (res->flags & IORESOURCE_IO)) {
+                       bus_res = res;
+                       break;
+               }
+
+       if (!bus_res) {
+               dev_err(&pdev->dev, "No resources available\n");
+               return -1;
+       }
+
        pci_eisa_root.dev              = &pdev->dev;
-       pci_eisa_root.res              = pdev->bus->resource[0];
-       pci_eisa_root.bus_base_addr    = pdev->bus->resource[0]->start;
+       pci_eisa_root.res              = bus_res;
+       pci_eisa_root.bus_base_addr    = bus_res->start;
        pci_eisa_root.slots            = EISA_MAX_SLOTS;
        pci_eisa_root.dma_mask         = pdev->dma_mask;
        dev_set_drvdata(pci_eisa_root.dev, &pci_eisa_root);