[PATCH V4 03/12] PCI/TPH: Add pcie_tph_modes() to query TPH modes

Wei Huang
2024-08-22T20:42:05Z

Add pcie_tph_modes() to allow drivers to query the TPH modes supported
by an endpoint device, as reported in the TPH Requester Capability
register. The modes are reported as a bitmask and current supported
modes include:

- PCI_TPH_CAP_NO_ST: NO ST Mode Supported
- PCI_TPH_CAP_INT_VEC: Interrupt Vector Mode Supported
- PCI_TPH_CAP_DEV_SPEC: Device Specific Mode Supported

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 | 33 +++++++++++++++++++++++++++++++++
include/linux/pci-tph.h | 18 ++++++++++++++++++
2 files changed, 51 insertions(+)
create mode 100644 include/linux/pci-tph.h

diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
index a547858c3f68..a28dced3097d 100644
--- a/drivers/pci/pcie/tph.c
+++ b/drivers/pci/pcie/tph.c
@@ -6,9 +6,42 @@
* Eric Van Tassell <Eric.VanTassell@amd.com>
* Wei Huang <wei.huang2@amd.com>
*/
+#include <linux/pci.h>
+#include <linux/pci-tph.h>

#include "../pci.h"

+static u8 get_st_modes(struct pci_dev *pdev)
+{
+ u32 reg;
+
+ pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
+ reg &= PCI_TPH_CAP_NO_ST | PCI_TPH_CAP_INT_VEC | PCI_TPH_CAP_DEV_SPEC;
+
+ return reg;
+}
+
+/**
+ * pcie_tph_modes - Get the ST modes supported by device
+ * @pdev: PCI device
+ *
+ * Returns a bitmask with all TPH modes supported by a device as shown in the
+ * TPH capability register. Current supported modes include:
+ * PCI_TPH_CAP_NO_ST - NO ST Mode Supported
+ * PCI_TPH_CAP_INT_VEC - Interrupt Vector Mode Supported
+ * PCI_TPH_CAP_DEV_SPEC - Device Specific Mode Supported
+ *
+ * Return: 0 when TPH is not supported, otherwise bitmask of supported modes
+ */
+int pcie_tph_modes(struct pci_dev *pdev)
+{
+ if (!pdev->tph_cap)
+ return 0;
+
+ return get_st_modes(pdev);
+}
+EXPORT_SYMBOL(pcie_tph_modes);
+
void pci_tph_init(struct pci_dev *pdev)
{
pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
new file mode 100644
index 000000000000..fa378afe9c7e
--- /dev/null
+++ b/include/linux/pci-tph.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * TPH (TLP Processing Hints)
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ * Eric Van Tassell <Eric.VanTassell@amd.com>
+ * Wei Huang <wei.huang2@amd.com>
+ */
+#ifndef LINUX_PCI_TPH_H
+#define LINUX_PCI_TPH_H
+
+#ifdef CONFIG_PCIE_TPH
+int pcie_tph_modes(struct pci_dev *pdev);
+#else
+static inline int pcie_tph_modes(struct pci_dev *pdev) { return 0; }
+#endif
+
+#endif /* LINUX_PCI_TPH_H */
--
2.45.1