pci: pcie_dw_common: introduce pcie_dw_find_capability()
Add PCIe config space capability search function specific for
the host controller, which are bridges *to* PCI devices but
are not PCI devices themselves.
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20241125-topic-pcie-controller-v1-1-45c20070dd53@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/drivers/pci/pcie_dw_common.c b/drivers/pci/pcie_dw_common.c
index 0673e51..7896127 100644
--- a/drivers/pci/pcie_dw_common.c
+++ b/drivers/pci/pcie_dw_common.c
@@ -267,6 +267,48 @@
pcie->io.bus_start, pcie->io.size);
}
+/*
+ * 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 pcie_dw_find_next_cap(struct pcie_dw *pci, u8 cap_ptr, u8 cap)
+{
+ u8 cap_id, next_cap_ptr;
+ u32 val;
+ u16 reg;
+
+ if (!cap_ptr)
+ return 0;
+
+ val = readl(pci->dbi_base + (cap_ptr & ~0x3));
+ reg = pci_conv_32_to_size(val, cap_ptr, 2);
+ cap_id = (reg & 0x00ff);
+
+ if (cap_id > PCI_CAP_ID_MAX)
+ return 0;
+
+ if (cap_id == cap)
+ return cap_ptr;
+
+ next_cap_ptr = (reg & 0xff00) >> 8;
+ return pcie_dw_find_next_cap(pci, next_cap_ptr, cap);
+}
+
+u8 pcie_dw_find_capability(struct pcie_dw *pci, u8 cap)
+{
+ u8 next_cap_ptr;
+ u32 val;
+ u16 reg;
+
+ val = readl(pci->dbi_base + (PCI_CAPABILITY_LIST & ~0x3));
+ reg = pci_conv_32_to_size(val, PCI_CAPABILITY_LIST, 2);
+
+ next_cap_ptr = (reg & 0x00ff);
+
+ return pcie_dw_find_next_cap(pci, next_cap_ptr, cap);
+}
+
/**
* pcie_dw_setup_host() - Setup the PCIe controller for RC opertaion
*
diff --git a/drivers/pci/pcie_dw_common.h b/drivers/pci/pcie_dw_common.h
index e0f7796..8cb99a1 100644
--- a/drivers/pci/pcie_dw_common.h
+++ b/drivers/pci/pcie_dw_common.h
@@ -139,6 +139,8 @@
int pcie_dw_write_config(struct udevice *bus, pci_dev_t bdf, uint offset, ulong value,
enum pci_size_t size);
+u8 pcie_dw_find_capability(struct pcie_dw *pci, u8 cap);
+
static inline void dw_pcie_dbi_write_enable(struct pcie_dw *pci, bool en)
{
u32 val;