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-rw-r--r--drivers/pci/bus.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 73aef51a28f0..8fb16188cd82 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -228,6 +228,49 @@ int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
}
EXPORT_SYMBOL(pci_bus_alloc_resource);
+/*
+ * The @idx resource of @dev should be a PCI-PCI bridge window. If this
+ * resource fits inside a window of an upstream bridge, do nothing. If it
+ * overlaps an upstream window but extends outside it, clip the resource so
+ * it fits completely inside.
+ */
+bool pci_bus_clip_resource(struct pci_dev *dev, int idx)
+{
+ struct pci_bus *bus = dev->bus;
+ struct resource *res = &dev->resource[idx];
+ struct resource orig_res = *res;
+ struct resource *r;
+ int i;
+
+ pci_bus_for_each_resource(bus, r, i) {
+ resource_size_t start, end;
+
+ if (!r)
+ continue;
+
+ if (resource_type(res) != resource_type(r))
+ continue;
+
+ start = max(r->start, res->start);
+ end = min(r->end, res->end);
+
+ if (start > end)
+ continue; /* no overlap */
+
+ if (res->start == start && res->end == end)
+ return false; /* no change */
+
+ res->start = start;
+ res->end = end;
+ dev_printk(KERN_DEBUG, &dev->dev, "%pR clipped to %pR\n",
+ &orig_res, res);
+
+ return true;
+ }
+
+ return false;
+}
+
void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
/**

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