diff options
| author | Niklas Cassel <cassel@kernel.org> | 2025-03-10 10:48:27 +0100 |
|---|---|---|
| committer | Krzysztof Wilczyński <kwilczynski@kernel.org> | 2025-03-14 16:13:19 +0000 |
| commit | e3d6957f177936281278d259029a1a2184ba50d4 (patch) | |
| tree | 7d9d367ace616ada2d612bc096102fd4c22c60d6 /drivers/pci/controller/dwc/pcie-designware-ep.c | |
| parent | 8189aa56dbed0bfb46b7b30d4d231f57ab17b3f4 (diff) | |
PCI: dwc: ep: Add dw_pcie_ep_hide_ext_capability()
Add dw_pcie_ep_hide_ext_capability() which can be used by an endpoint
controller driver to hide a capability.
This can be useful to hide a capability that is buggy, such that the
host side does not try to enable the buggy capability.
Suggested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Link: https://lore.kernel.org/r/20250310094826.842681-5-cassel@kernel.org
Diffstat (limited to 'drivers/pci/controller/dwc/pcie-designware-ep.c')
| -rw-r--r-- | drivers/pci/controller/dwc/pcie-designware-ep.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c index 2212609632c4..5a6174e107c2 100644 --- a/drivers/pci/controller/dwc/pcie-designware-ep.c +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c @@ -102,6 +102,45 @@ static u8 dw_pcie_ep_find_capability(struct dw_pcie_ep *ep, u8 func_no, u8 cap) return __dw_pcie_ep_find_next_cap(ep, func_no, next_cap_ptr, cap); } +/** + * dw_pcie_ep_hide_ext_capability - Hide a capability from the linked list + * @pci: DWC PCI device + * @prev_cap: Capability preceding the capability that should be hidden + * @cap: Capability that should be hidden + * + * Return: 0 if success, errno otherwise. + */ +int dw_pcie_ep_hide_ext_capability(struct dw_pcie *pci, u8 prev_cap, u8 cap) +{ + u16 prev_cap_offset, cap_offset; + u32 prev_cap_header, cap_header; + + prev_cap_offset = dw_pcie_find_ext_capability(pci, prev_cap); + if (!prev_cap_offset) + return -EINVAL; + + prev_cap_header = dw_pcie_readl_dbi(pci, prev_cap_offset); + cap_offset = PCI_EXT_CAP_NEXT(prev_cap_header); + cap_header = dw_pcie_readl_dbi(pci, cap_offset); + + /* cap must immediately follow prev_cap. */ + if (PCI_EXT_CAP_ID(cap_header) != cap) + return -EINVAL; + + /* Clear next ptr. */ + prev_cap_header &= ~GENMASK(31, 20); + + /* Set next ptr to next ptr of cap. */ + prev_cap_header |= cap_header & GENMASK(31, 20); + + dw_pcie_dbi_ro_wr_en(pci); + dw_pcie_writel_dbi(pci, prev_cap_offset, prev_cap_header); + dw_pcie_dbi_ro_wr_dis(pci); + + return 0; +} +EXPORT_SYMBOL_GPL(dw_pcie_ep_hide_ext_capability); + static int dw_pcie_ep_write_header(struct pci_epc *epc, u8 func_no, u8 vfunc_no, struct pci_epf_header *hdr) { |