[PATCH V3 05/10] PCI/TPH: Introduce API to check interrupt vector mode support

[Wei Huang <wei.huang2@amd.com>]

Add an API function to allow endpoint device drivers to check
if the interrupt vector mode is allowed. If allowed, drivers
can proceed with updating ST tags.

Co-developed-by: Eric Van Tassell <Eric.VanTassell@amd.com>
Signed-off-by: Eric Van Tassell <Eric.VanTassell@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
---
 drivers/pci/pcie/tph.c  | 29 +++++++++++++++++++++++++++++
 include/linux/pci-tph.h |  3 +++
 2 files changed, 32 insertions(+)

diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
index fb8e2f920712..7183370b0977 100644
--- a/drivers/pci/pcie/tph.c
+++ b/drivers/pci/pcie/tph.c
@@ -39,6 +39,17 @@ static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type)
 	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg_val);
 }
 
+static bool int_vec_mode_supported(struct pci_dev *pdev)
+{
+	u32 reg_val;
+	u8 mode;
+
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg_val);
+	mode = FIELD_GET(PCI_TPH_CAP_INT_VEC, reg_val);
+
+	return !!mode;
+}
+
 void pcie_tph_set_nostmode(struct pci_dev *pdev)
 {
 	if (!pdev->tph_cap)
@@ -60,3 +71,21 @@ void pcie_tph_init(struct pci_dev *pdev)
 {
 	pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
 }
+
+/**
+ * pcie_tph_intr_vec_supported() - Check if interrupt vector mode supported for dev
+ * @pdev: pci device
+ *
+ * Return:
+ *        true : intr vector mode supported
+ *        false: intr vector mode not supported
+ */
+bool pcie_tph_intr_vec_supported(struct pci_dev *pdev)
+{
+	if (!pdev->tph_cap || pci_tph_disabled() || !pdev->msix_enabled ||
+	    !int_vec_mode_supported(pdev))
+		return false;
+
+	return true;
+}
+EXPORT_SYMBOL(pcie_tph_intr_vec_supported);
diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
index 8fce3969277c..854677651d81 100644
--- a/include/linux/pci-tph.h
+++ b/include/linux/pci-tph.h
@@ -12,9 +12,12 @@
 #ifdef CONFIG_PCIE_TPH
 void pcie_tph_disable(struct pci_dev *dev);
 void pcie_tph_set_nostmode(struct pci_dev *dev);
+bool pcie_tph_intr_vec_supported(struct pci_dev *dev);
 #else
 static inline void pcie_tph_disable(struct pci_dev *dev) {}
 static inline void pcie_tph_set_nostmode(struct pci_dev *dev) {}
+static inline bool pcie_tph_intr_vec_supported(struct pci_dev *dev)
+{ return false; }
 #endif
 
 #endif /* LINUX_PCI_TPH_H */
-- 
2.45.1