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: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

drivers/pci/pci-uclass.c

@@ -1055,6 +1055,19 @@ int pci_get_regions(struct udevice *dev, struct pci_region **iop,
 	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",

include/pci.h

@@ -1166,6 +1166,15 @@ struct udevice *pci_get_controller(struct udevice *dev);
 int pci_get_regions(struct udevice *dev, struct pci_region **iop,
 		    struct pci_region **memp, struct pci_region **prefp);
 
+/**
+ * dm_pci_read_bar32() - read a base address register from a device
+ *
+ * @dev:	Device to check
+ * @barnum:	Bar number to read (numbered from 0)
+ * @return: value of BAR
+ */
+u32 dm_pci_read_bar32(struct udevice *dev, int barnum);
+
 /**
  * dm_pci_find_device() - find a device by vendor/device ID
  *