Add new helper pcie_tph_supported() with want_ext parameter:
- want_ext = false: Check if device has valid TPH capability;
- want_ext = true: Check hardware Extended TPH support.

This helper is prepared for follow-up VFIO TPH virtualization patches to
uniformly query basic TPH existence and Extended TPH capability.

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
---
 drivers/pci/tph.c       | 19 +++++++++++++++++++
 include/linux/pci-tph.h |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
index 6c4623cacc85..95280aab4fb5 100644
--- a/drivers/pci/tph.c
+++ b/drivers/pci/tph.c
@@ -600,3 +600,22 @@ void pci_tph_init(struct pci_dev *pdev)
 	save_size = sizeof(u32) + num_entries * sizeof(u16);
 	pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_TPH, save_size);
 }
+
+/**
+ * pcie_tph_supported - Check TPH capability attribute
+ * @pdev: PCI device to query
+ * @want_ext: false - check TPH cap exists; true - check EXT_TPH support
+ *
+ * Return: true on matched condition, false otherwise
+ */
+bool pcie_tph_supported(struct pci_dev *pdev, bool want_ext)
+{
+	if (!pdev->tph_cap)
+		return false;
+
+	if (!want_ext)
+		return true;
+
+	return pdev->tph_ext_support;
+}
+EXPORT_SYMBOL(pcie_tph_supported);
diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
index e4f7045fc152..5917a0694c1d 100644
--- a/include/linux/pci-tph.h
+++ b/include/linux/pci-tph.h
@@ -36,6 +36,7 @@ int pcie_enable_tph_explicit(struct pci_dev *pdev, int mode, bool extended);
 u8 pcie_tph_enabled_req_type(struct pci_dev *pdev);
 u16 pcie_tph_get_st_table_size(struct pci_dev *pdev);
 u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev);
+bool pcie_tph_supported(struct pci_dev *pdev, bool want_ext);
 #else
 static inline int pcie_tph_set_st_entry(struct pci_dev *pdev,
 					unsigned int index, u16 tag)
@@ -60,6 +61,8 @@ static inline u16 pcie_tph_get_st_table_size(struct pci_dev *pdev)
 { return 0; }
 static inline u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev)
 { return PCI_TPH_LOC_NONE; }
+static inline bool pcie_tph_supported(struct pci_dev *pdev, bool want_ext)
+{ return false; }
 #endif
 
 #endif /* LINUX_PCI_TPH_H */
-- 
2.17.1