[PATCH V4 05/12] PCI/TPH: Add pcie_disable_tph() to disable TPH

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

Turn off TPH support for a device and clean all related states.

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  | 22 ++++++++++++++++++++++
 include/linux/pci-tph.h |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
index 14ad8c5e895c..08ce4fdeb160 100644
--- a/drivers/pci/pcie/tph.c
+++ b/drivers/pci/pcie/tph.c
@@ -40,6 +40,28 @@ static u8 get_rp_completer_type(struct pci_dev *pdev)
 	return FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg);
 }
 
+/**
+ * pcie_disable_tph - Turn off TPH support for device
+ * @pdev: PCI device
+ *
+ * Return: none
+ */
+void pcie_disable_tph(struct pci_dev *pdev)
+{
+	if (!pdev->tph_cap)
+		return;
+
+	if (!pdev->tph_enabled)
+		return;
+
+	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, 0);
+
+	pdev->tph_mode = 0;
+	pdev->tph_req_type = 0;
+	pdev->tph_enabled = 0;
+}
+EXPORT_SYMBOL(pcie_disable_tph);
+
 /**
  * pcie_enable_tph - Enable TPH support for device using a specific ST mode
  * @pdev: PCI device
diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
index cdf561076484..422d395ade68 100644
--- a/include/linux/pci-tph.h
+++ b/include/linux/pci-tph.h
@@ -10,9 +10,11 @@
 #define LINUX_PCI_TPH_H
 
 #ifdef CONFIG_PCIE_TPH
+void pcie_disable_tph(struct pci_dev *pdev);
 int pcie_enable_tph(struct pci_dev *pdev, int mode);
 int pcie_tph_modes(struct pci_dev *pdev);
 #else
+static inline void pcie_disable_tph(struct pci_dev *pdev) { }
 static inline int pcie_enable_tph(struct pci_dev *pdev, int mode)
 { return -EINVAL; }
 static inline int pcie_tph_modes(struct pci_dev *pdev) { return 0; }
-- 
2.45.1