[v7 3/5] PCI: dwc: Use common PCI host bridge APIs for finding the capabilities

Hans Zhang
2025-04-02T04:21:51Z

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 DWC driver.

Signed-off-by: Hans Zhang <18255117159@163.com>
---
Changes since v6:
https://lore.kernel.org/linux-pci/20250323164852.430546-3-18255117159@163.com/

- The patch commit message were modified.

Changes since v5:
https://lore.kernel.org/linux-pci/20250321163803.391056-3-18255117159@163.com/

- Kconfig add "select PCI_HOST_HELPERS"
---
drivers/pci/controller/dwc/pcie-designware.c | 72 ++------------------
1 file changed, 7 insertions(+), 65 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 145e7f579072..e9a9a80b1085 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -203,83 +203,25 @@ void dw_pcie_version_detect(struct dw_pcie *pci)
pci->type = ver;
}

-/*
- * These interfaces resemble the pci_find_*capability() interfaces, but these
- * are for configuring host controllers, which are bridges *to* PCI devices but
- * are not PCI devices themselves.
- */
-static u8 __dw_pcie_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
- u8 cap)
+static int dw_pcie_read_cfg(void *priv, int where, int size, u32 *val)
{
- u8 cap_id, next_cap_ptr;
- u16 reg;
-
- if (!cap_ptr)
- return 0;
-
- reg = dw_pcie_readw_dbi(pci, cap_ptr);
- cap_id = (reg & 0x00ff);
-
- if (cap_id > PCI_CAP_ID_MAX)
- return 0;
+ struct dw_pcie *pcie = priv;

- if (cap_id == cap)
- return cap_ptr;
+ *val = dw_pcie_read_dbi(pcie, where, size);

- next_cap_ptr = (reg & 0xff00) >> 8;
- return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
+ return PCIBIOS_SUCCESSFUL;
}

u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
{
- u8 next_cap_ptr;
- u16 reg;
-
- reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST);
- next_cap_ptr = (reg & 0x00ff);
-
- return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
+ return PCI_FIND_NEXT_CAP_TTL(dw_pcie_read_cfg, PCI_CAPABILITY_LIST, cap,
+ pcie);
}
EXPORT_SYMBOL_GPL(dw_pcie_find_capability);

-static u16 dw_pcie_find_next_ext_capability(struct dw_pcie *pci, u16 start,
- u8 cap)
-{
- u32 header;
- int ttl;
- int pos = PCI_CFG_SPACE_SIZE;
-
- /* minimum 8 bytes per capability */
- ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
-
- if (start)
- pos = start;
-
- header = dw_pcie_readl_dbi(pci, pos);
- /*
- * If we have no capabilities, this is indicated by cap ID,
- * cap version and next pointer all being 0.
- */
- if (header == 0)
- return 0;
-
- while (ttl-- > 0) {
- if (PCI_EXT_CAP_ID(header) == cap && pos != start)
- return pos;
-
- pos = PCI_EXT_CAP_NEXT(header);
- if (pos < PCI_CFG_SPACE_SIZE)
- break;
-
- header = dw_pcie_readl_dbi(pci, pos);
- }
-
- return 0;
-}
-
u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap)
{
- return dw_pcie_find_next_ext_capability(pci, 0, cap);
+ return PCI_FIND_NEXT_EXT_CAPABILITY(dw_pcie_read_cfg, 0, cap, pcie);
}
EXPORT_SYMBOL_GPL(dw_pcie_find_ext_capability);

--
2.25.1