PNP: disable PNP motherboard resources that overlap PCI BARs

Some BIOSes have PNP motherboard devices with resources that
partially overlap PCI BARs. The PNP system driver claims these
motherboard resources, which prevents the normal PCI driver from
requesting them later.

This patch disables the PNP resources that conflict with PCI BARs
so they won't be claimed by the PNP system driver.

Of course, this only works if PCI devices have already been enumerated.
Currently this is the case because PCI devices are discovered before
any PNP init via this path:

acpi_pci_root_init() -> acpi_pci_root_add() -> pci_acpi_scan_root() ->
pci_scan_bus_parented() -> pci_scan_child_bus() -> ...

Avuton Olrich tested this and confirmed that it fixes his ALSA sound
card (see http://lkml.org/lkml/2008/1/27/168).

References:
https://bugzilla.redhat.com/show_bug.cgi?id=280641
https://bugzilla.redhat.com/show_bug.cgi?id=313491
http://lkml.org/lkml/2008/1/9/449
http://thread.gmane.org/gmane.linux.acpi.devel/27312
http://lkml.org/lkml/2008/1/27/168

Signed-off-by: Bjorn Helgaas <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/pnp/quirks.c

···
 		       "pnp: SB audio device quirk - increasing port range\n");
 }
 
+
+#include <linux/pci.h>
+
+static void quirk_system_pci_resources(struct pnp_dev *dev)
+{
+	struct pci_dev *pdev = NULL;
+	resource_size_t pnp_start, pnp_end, pci_start, pci_end;
+	int i, j;
+
+	/*
+	 * Some BIOSes have PNP motherboard devices with resources that
+	 * partially overlap PCI BARs.  The PNP system driver claims these
+	 * motherboard resources, which prevents the normal PCI driver from
+	 * requesting them later.
+	 *
+	 * This patch disables the PNP resources that conflict with PCI BARs
+	 * so they won't be claimed by the PNP system driver.
+	 */
+	for_each_pci_dev(pdev) {
+		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
+			if (!(pci_resource_flags(pdev, i) & IORESOURCE_MEM) ||
+			    pci_resource_len(pdev, i) == 0)
+				continue;
+
+			pci_start = pci_resource_start(pdev, i);
+			pci_end = pci_resource_end(pdev, i);
+			for (j = 0; j < PNP_MAX_MEM; j++) {
+				if (!pnp_mem_valid(dev, j) ||
+				    pnp_mem_len(dev, j) == 0)
+					continue;
+
+				pnp_start = pnp_mem_start(dev, j);
+				pnp_end = pnp_mem_end(dev, j);
+
+				/*
+				 * If the PNP region doesn't overlap the PCI
+				 * region at all, there's no problem.
+				 */
+				if (pnp_end < pci_start || pnp_start > pci_end)
+					continue;
+
+				/*
+				 * If the PNP region completely encloses (or is
+				 * at least as large as) the PCI region, that's
+				 * also OK.  For example, this happens when the
+				 * PNP device describes a bridge with PCI
+				 * behind it.
+				 */
+				if (pnp_start <= pci_start &&
+				    pnp_end >= pci_end)
+					continue;
+
+				/*
+				 * Otherwise, the PNP region overlaps *part* of
+				 * the PCI region, and that might prevent a PCI
+				 * driver from requesting its resources.
+				 */
+				dev_warn(&dev->dev, "mem resource "
+					"(0x%llx-0x%llx) overlaps %s BAR %d "
+					"(0x%llx-0x%llx), disabling\n",
+					(unsigned long long) pnp_start,
+					(unsigned long long) pnp_end,
+					pci_name(pdev), i,
+					(unsigned long long) pci_start,
+					(unsigned long long) pci_end);
+				pnp_mem_flags(dev, j) = 0;
+			}
+		}
+	}
+}
+
 /*
  *  PnP Quirks
  *  Cards or devices that need some tweaking due to incomplete resource info
···
 	{"CTL0043", quirk_sb16audio_resources},
 	{"CTL0044", quirk_sb16audio_resources},
 	{"CTL0045", quirk_sb16audio_resources},
+	{"PNP0c01", quirk_system_pci_resources},
+	{"PNP0c02", quirk_system_pci_resources},
 	{""}
 };