[PATCH] PCI: xilinx-nwl: Avoid crashing if configuring when the link is down

[Sean Anderson]

The ECAM will return a slave error if we access non-root devices while
the link is down. Add a check for this like Linux does so we don't
crash.

Fixes: 2f5ad77cfea ("PCI: zynqmp: Add ZynqMP NWL PCIe root port driver")
Signed-off-by: Sean Anderson <sean.anderson at linux.dev>
---

 drivers/pci/pcie-xilinx-nwl.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/pcie-xilinx-nwl.c b/drivers/pci/pcie-xilinx-nwl.c
index e03ab3be912..ab597c83e47 100644
--- a/drivers/pci/pcie-xilinx-nwl.c
+++ b/drivers/pci/pcie-xilinx-nwl.c
@@ -135,6 +135,13 @@ struct nwl_pcie {
 	u32 ecam_value;
 };
 
+static bool nwl_pcie_link_up(struct nwl_pcie *pcie)
+{
+	if (readl(pcie->pcireg_base + PS_LINKUP_OFFSET) & PCIE_PHY_LINKUP_BIT)
+		return true;
+	return false;
+}
+
 static int nwl_pcie_config_address(const struct udevice *bus,
 				   pci_dev_t bdf, uint offset,
 				   void **paddress)
@@ -142,6 +149,9 @@ static int nwl_pcie_config_address(const struct udevice *bus,
 	struct nwl_pcie *pcie = dev_get_priv(bus);
 	void *addr;
 
+	if (PCI_BUS(bdf) != dev_seq(bus) && !nwl_pcie_link_up(pcie))
+		return -EIO;
+
 	addr = pcie->ecam_base;
 	addr += PCIE_ECAM_OFFSET(PCI_BUS(bdf) - dev_seq(bus),
 				 PCI_DEV(bdf), PCI_FUNC(bdf), offset);
@@ -181,13 +191,6 @@ static inline void nwl_bridge_writel(struct nwl_pcie *pcie, u32 val, u32 off)
 	writel(val, pcie->breg_base + off);
 }
 
-static bool nwl_pcie_link_up(struct nwl_pcie *pcie)
-{
-	if (readl(pcie->pcireg_base + PS_LINKUP_OFFSET) & PCIE_PHY_LINKUP_BIT)
-		return true;
-	return false;
-}
-
 static bool nwl_phy_link_up(struct nwl_pcie *pcie)
 {
 	if (readl(pcie->pcireg_base + PS_LINKUP_OFFSET) & PHY_RDY_LINKUP_BIT)
-- 
2.35.1.1320.gc452695387.dirty

base-commit: beab3fe49e1e9209dd32fe2791e7ac706038460f
branch: pcie_nwl_ecam