p2sb: Factor out p2sb_read_from_cache()

To prepare for the following fix, factor out the code to read the P2SB
resource from the cache to the new function p2sb_read_from_cache().

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20241128002836.373745-2-shinichiro.kawasaki@wdc.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: kawasaki

drivers/platform/x86/p2sb.c

@@ -172,6 +172,22 @@ static int p2sb_cache_resources(void)
 	return ret;
 }
 
+static int p2sb_read_from_cache(struct pci_bus *bus, unsigned int devfn,
+				struct resource *mem)
+{
+	struct p2sb_res_cache *cache = &p2sb_resources[PCI_FUNC(devfn)];
+
+	if (cache->bus_dev_id != bus->dev.id)
+		return -ENODEV;
+
+	if (!p2sb_valid_resource(&cache->res))
+		return -ENOENT;
+
+	memcpy(mem, &cache->res, sizeof(*mem));
+
+	return 0;
+}
+
 /**
  * p2sb_bar - Get Primary to Sideband (P2SB) bridge device BAR
  * @bus: PCI bus to communicate with
@@ -188,24 +204,14 @@ static int p2sb_cache_resources(void)
  */
 int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
 {
-	struct p2sb_res_cache *cache;
-
 	bus = p2sb_get_bus(bus);
 	if (!bus)
 		return -ENODEV;
 
 	if (!devfn)
 		p2sb_get_devfn(&devfn);
 
-	cache = &p2sb_resources[PCI_FUNC(devfn)];
-	if (cache->bus_dev_id != bus->dev.id)
-		return -ENODEV;
-
-	if (!p2sb_valid_resource(&cache->res))
-		return -ENOENT;
-
-	memcpy(mem, &cache->res, sizeof(*mem));
-	return 0;
+	return p2sb_read_from_cache(bus, devfn, mem);
 }
 EXPORT_SYMBOL_GPL(p2sb_bar);