[PATCH v7 2/5] PCI: dwc: Add helper to find the Vendor Specific Extended Capability (VSEC)

Shradha Todi
2025-02-22T10:58:59Z

dw_pcie_find_vsec_capability() is used by upcoming DWC APIs to find the
VSEC capabilities like PTM, RAS etc.

Co-developed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Shradha Todi <shradha.t@samsung.com>
---
drivers/pci/controller/dwc/pcie-designware.c | 40 ++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 145e7f579072..a7c0671c6715 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -16,6 +16,7 @@
#include <linux/gpio/consumer.h>
#include <linux/ioport.h>
#include <linux/of.h>
+#include <linux/pcie-dwc.h>
#include <linux/platform_device.h>
#include <linux/sizes.h>
#include <linux/types.h>
@@ -283,6 +284,45 @@ u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap)
}
EXPORT_SYMBOL_GPL(dw_pcie_find_ext_capability);

+static u16 __dw_pcie_find_vsec_capability(struct dw_pcie *pci, u16 vendor_id,
+ u16 vsec_id)
+{
+ u16 vsec = 0;
+ u32 header;
+
+ if (vendor_id != dw_pcie_readw_dbi(pci, PCI_VENDOR_ID))
+ return 0;
+
+ while ((vsec = dw_pcie_find_next_ext_capability(pci, vsec,
+ PCI_EXT_CAP_ID_VNDR))) {
+ header = dw_pcie_readl_dbi(pci, vsec + PCI_VNDR_HEADER);
+ if (PCI_VNDR_HEADER_ID(header) == vsec_id)
+ return vsec;
+ }
+
+ return 0;
+}
+
+static u16 dw_pcie_find_vsec_capability(struct dw_pcie *pci,
+ const struct dwc_pcie_vsec_id *vsec_ids)
+{
+ const struct dwc_pcie_vsec_id *vid;
+ u16 vsec;
+ u32 header;
+
+ for (vid = vsec_ids; vid->vendor_id; vid++) {
+ vsec = __dw_pcie_find_vsec_capability(pci, vid->vendor_id,
+ vid->vsec_id);
+ if (vsec) {
+ header = dw_pcie_readl_dbi(pci, vsec + PCI_VNDR_HEADER);
+ if (PCI_VNDR_HEADER_REV(header) == vid->vsec_rev)
+ return vsec;
+ }
+ }
+
+ return 0;
+}
+
int dw_pcie_read(void __iomem *addr, int size, u32 *val)
{
if (!IS_ALIGNED((uintptr_t)addr, size)) {
--
2.17.1