PCI: rockchip-ep: Improve rockchip_pcie_ep_map_addr()

Add a check to verify that the outbound region to be used for mapping an
address is not already in use.

Link: https://lore.kernel.org/r/20241017015849.190271-5-dlemoal@kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Author: damien-lemoal

drivers/pci/controller/pcie-rockchip-ep.c

@@ -246,6 +246,9 @@ static int rockchip_pcie_ep_map_addr(struct pci_epc *epc, u8 fn, u8 vfn,
 	struct rockchip_pcie *pcie = &ep->rockchip;
 	u32 r = rockchip_ob_region(addr);
 
+	if (test_bit(r, &ep->ob_region_map))
+		return -EBUSY;
+
 	rockchip_pcie_prog_ep_ob_atu(pcie, fn, r, addr, pci_addr, size);
 
 	set_bit(r, &ep->ob_region_map);