[v7 4/5] PCI: cadence: Use common PCI host bridge APIs for finding the capabilities

[Hans Zhang]

Use the PCI core is now exposing generic macros for the host bridges to
search for the PCIe capabilities, make use of them in the CDNS driver.

Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
---
Changes since v6:
https://lore.kernel.org/linux-pci/20250323164852.430546-4-18255117159@xxxxxxx/

- The patch commit message were modified.

Changes since v5:
https://lore.kernel.org/linux-pci/20250321163803.391056-4-18255117159@xxxxxxx

- Kconfig add "select PCI_HOST_HELPERS"
---
 drivers/pci/controller/cadence/pcie-cadence.c | 28 +++++++++++++++++++
 drivers/pci/controller/cadence/pcie-cadence.h | 13 +++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
index 204e045aed8c..ca4a1a809fcb 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.c
+++ b/drivers/pci/controller/cadence/pcie-cadence.c
@@ -7,6 +7,34 @@
 #include <linux/of.h>
 
 #include "pcie-cadence.h"
+#include "../../pci.h"
+
+static int cdns_pcie_read_cfg(void *priv, int where, int size, u32 *val)
+{
+	struct cdns_pcie *pcie = priv;
+
+	if (size == 4)
+		*val = cdns_pcie_readl(pcie, where);
+	else if (size == 2)
+		*val = cdns_pcie_readw(pcie, where);
+	else if (size == 1)
+		*val = cdns_pcie_readb(pcie, where);
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+u8 cdns_pcie_find_capability(struct cdns_pcie *pcie, u8 cap)
+{
+	return PCI_FIND_NEXT_CAP_TTL(cdns_pcie_read_cfg, PCI_CAPABILITY_LIST,
+				     cap, pcie);
+}
+EXPORT_SYMBOL_GPL(cdns_pcie_find_capability);
+
+u16 cdns_pcie_find_ext_capability(struct cdns_pcie *pcie, u8 cap)
+{
+	return PCI_FIND_NEXT_EXT_CAPABILITY(cdns_pcie_read_cfg, 0, cap, pcie);
+}
+EXPORT_SYMBOL_GPL(cdns_pcie_find_ext_capability);
 
 void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie)
 {
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index f5eeff834ec1..dd7cb6b6b291 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -398,6 +398,16 @@ static inline u32 cdns_pcie_readl(struct cdns_pcie *pcie, u32 reg)
 	return readl(pcie->reg_base + reg);
 }
 
+static inline u32 cdns_pcie_readw(struct cdns_pcie *pcie, u32 reg)
+{
+	return readw(pcie->reg_base + reg);
+}
+
+static inline u32 cdns_pcie_readb(struct cdns_pcie *pcie, u32 reg)
+{
+	return readb(pcie->reg_base + reg);
+}
+
 static inline u32 cdns_pcie_read_sz(void __iomem *addr, int size)
 {
 	void __iomem *aligned_addr = PTR_ALIGN_DOWN(addr, 0x4);
@@ -557,6 +567,9 @@ static inline int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep)
 }
 #endif
 
+u8 cdns_pcie_find_capability(struct cdns_pcie *pcie, u8 cap);
+u16 cdns_pcie_find_ext_capability(struct cdns_pcie *pcie, u8 cap);
+
 void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie);
 
 void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn,
-- 
2.25.1