[PATCH v3 01/16] PCI: dwc: Add pcie_cap field and helper in designware header
From: Hans Zhang <18255117159@163.com>
Date: 2026-07-20 15:08:20
Also in:
imx, linux-amlogic, linux-arm-msm, linux-pci, linux-riscv, linux-rockchip, linux-tegra, lkml, spacemit
Subsystem:
pci driver for synopsys designware, pci native host bridge and endpoint drivers, pci subsystem, the rest · Maintainers:
Jingoo Han, Manivannan Sadhasivam, Lorenzo Pieralisi, Krzysztof Wilczyński, Bjorn Helgaas, Linus Torvalds
Add a pcie_cap field to struct dw_pcie to store the offset of the PCI Express Capability structure. Provide a helper dw_pcie_get_pcie_cap() which performs the capability search on first call and caches the result. This is a preparatory step for replacing repetitive capability searches in both core and platform drivers. Signed-off-by: Hans Zhang <18255117159@163.com> --- drivers/pci/controller/dwc/pcie-designware.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index de4b245b1758..8113efd33a24 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h@@ -591,6 +591,8 @@ struct dw_pcie { * use_parent_dt_ranges to true to avoid this warning. */ bool use_parent_dt_ranges; + + u8 pcie_cap; /* PCIe capability offset */ }; #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
@@ -829,6 +831,21 @@ static inline void dw_pcie_dbi_ro_wr_dis(struct dw_pcie *pci) dw_pcie_writel_dbi(pci, reg, val); } +/** + * dw_pcie_get_pcie_cap() - Return cached PCIe Capability offset + * @pci: DWC instance + * + * Finds and caches the offset of PCI_CAP_ID_EXP on first call. + * Returns 0 if the capability is not present. + */ +static inline u8 dw_pcie_get_pcie_cap(struct dw_pcie *pci) +{ + if (!pci->pcie_cap) + pci->pcie_cap = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP); + + return pci->pcie_cap; +} + static inline int dw_pcie_start_link(struct dw_pcie *pci) { if (pci->ops && pci->ops->start_link)
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2.34.1