[PATCH v2 1/3] PCI: cadence: Fix Root Port configuration space access for LGA IP

[Hans Zhang]

On LGA (Legacy) Cadence IP, the Root Port configuration space is
located at offset CDNS_PCIE_RP_BASE (0x00200000) from the controller's
base address. However, the standard accessors cdns_pcie_read_cfg_*()
did not include this offset when operating in RC mode, causing any
configuration read (including capability list walking) to access the
wrong register region (Local Management space).

Additionally, cdns_pcie_read_cfg_dword() used a direct readl()
instead of the more general cdns_pcie_read_sz(), breaking symmetry
with byte/word accesses.

Fix this by:

Adding CDNS_PCIE_RP_BASE to the address for RC mode on non-HPA
(i.e. LGA) IP.

Replacing cdns_pcie_readl() with cdns_pcie_read_sz() in the dword
accessor for consistency.

This change enables correct capability discovery for Root Ports on LGA
platforms.

Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
---
 drivers/pci/controller/cadence/pcie-cadence.h | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index a1c531fd2061..c057f4b393e6 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -433,6 +433,9 @@ static inline int cdns_pcie_read_cfg_byte(struct cdns_pcie *pcie, int where,
 {
 	void __iomem *addr = pcie->reg_base + where;
 
+	if ((pcie->is_rc) && (!pcie->is_hpa))
+		addr += CDNS_PCIE_RP_BASE;
+
 	*val = cdns_pcie_read_sz(addr, 0x1);
 	return PCIBIOS_SUCCESSFUL;
 }
@@ -442,6 +445,9 @@ static inline int cdns_pcie_read_cfg_word(struct cdns_pcie *pcie, int where,
 {
 	void __iomem *addr = pcie->reg_base + where;
 
+	if ((pcie->is_rc) && (!pcie->is_hpa))
+		addr += CDNS_PCIE_RP_BASE;
+
 	*val = cdns_pcie_read_sz(addr, 0x2);
 	return PCIBIOS_SUCCESSFUL;
 }
@@ -449,7 +455,12 @@ static inline int cdns_pcie_read_cfg_word(struct cdns_pcie *pcie, int where,
 static inline int cdns_pcie_read_cfg_dword(struct cdns_pcie *pcie, int where,
 					   u32 *val)
 {
-	*val = cdns_pcie_readl(pcie, where);
+	void __iomem *addr = pcie->reg_base + where;
+
+	if ((pcie->is_rc) && (!pcie->is_hpa))
+		addr += CDNS_PCIE_RP_BASE;
+
+	*val = cdns_pcie_read_sz(addr, 0x4);
 	return PCIBIOS_SUCCESSFUL;
 }
 
-- 
2.34.1