dm: pci: Add a function to read a PCI BAR

Add a driver-model function for reading the PCI BAR from a device.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index dea0cb6..7a886f2 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -1055,6 +1055,19 @@
 	return (*iop != NULL) + (*memp != NULL) + (*prefp != NULL);
 }
 
+u32 dm_pci_read_bar32(struct udevice *dev, int barnum)
+{
+	u32 addr;
+	int bar;
+
+	bar = PCI_BASE_ADDRESS_0 + barnum * 4;
+	dm_pci_read_config32(dev, bar, &addr);
+	if (addr & PCI_BASE_ADDRESS_SPACE_IO)
+		return addr & PCI_BASE_ADDRESS_IO_MASK;
+	else
+		return addr & PCI_BASE_ADDRESS_MEM_MASK;
+}
+
 UCLASS_DRIVER(pci) = {
 	.id		= UCLASS_PCI,
 	.name		= "pci",