PCI: Add pci_find_resource()

Add a new helper function pci_find_resource() that can be used to find out
whether a given resource (for example from a child device) is contained
within given PCI device's standard resources.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/pci.c

@@ -479,6 +479,30 @@ struct resource *pci_find_parent_resource(const struct pci_dev *dev,
 }
 EXPORT_SYMBOL(pci_find_parent_resource);
 
+/**
+ * pci_find_resource - Return matching PCI device resource
+ * @dev: PCI device to query
+ * @res: Resource to look for
+ *
+ * Goes over standard PCI resources (BARs) and checks if the given resource
+ * is partially or fully contained in any of them. In that case the
+ * matching resource is returned, %NULL otherwise.
+ */
+struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res)
+{
+	int i;
+
+	for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+		struct resource *r = &dev->resource[i];
+
+		if (r->start && resource_contains(r, res))
+			return r;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(pci_find_resource);
+
 /**
  * pci_find_pcie_root_port - return PCIe Root Port
  * @dev: PCI device to query

include/linux/pci.h

@@ -1126,6 +1126,7 @@ void pdev_enable_device(struct pci_dev *);
 int pci_enable_resources(struct pci_dev *, int mask);
 void pci_fixup_irqs(u8 (*)(struct pci_dev *, u8 *),
 		    int (*)(const struct pci_dev *, u8, u8));
+struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res);
 #define HAVE_PCI_REQ_REGIONS	2
 int __must_check pci_request_regions(struct pci_dev *, const char *);
 int __must_check pci_request_regions_exclusive(struct pci_dev *, const char *);
@@ -1542,6 +1543,9 @@ static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state,
 				  int enable)
 { return 0; }
 
+static inline struct resource *pci_find_resource(struct pci_dev *dev,
+						 struct resource *res)
+{ return NULL; }
 static inline int pci_request_regions(struct pci_dev *dev, const char *res_name)
 { return -EIO; }
 static inline void pci_release_regions(struct pci_dev *dev) { }