[PATCH V2 1/9] PCI: Introduce PCIe TPH support framework

Wei Huang
2024-05-31T21:39:08Z

This patch implements the framework for PCIe TPH support. It introduces
tph.c source file, along with CONFIG_PCIE_TPH, to Linux PCIe subsystem.
A new member, named tph_cap, is also introduced in pci_dev to cache TPH
capability offset.

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/pci.h | 6 ++++++
drivers/pci/pcie/Kconfig | 10 ++++++++++
drivers/pci/pcie/Makefile | 1 +
drivers/pci/pcie/tph.c | 28 ++++++++++++++++++++++++++++
drivers/pci/probe.c | 1 +
include/linux/pci.h | 4 ++++
6 files changed, 50 insertions(+)
create mode 100644 drivers/pci/pcie/tph.c

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fd44565c4756..b371b5b45f86 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -506,6 +506,12 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)

#endif /* CONFIG_PCI_IOV */

+#ifdef CONFIG_PCIE_TPH
+void pcie_tph_init(struct pci_dev *dev);
+#else
+static inline void pcie_tph_init(struct pci_dev *dev) {}
+#endif
+
#ifdef CONFIG_PCIE_PTM
void pci_ptm_init(struct pci_dev *dev);
void pci_save_ptm_state(struct pci_dev *dev);
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 17919b99fa66..d22857325b3e 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -155,3 +155,13 @@ config PCIE_EDR
the PCI Firmware Specification r3.2. Enable this if you want to
support hybrid DPC model which uses both firmware and OS to
implement DPC.
+
+config PCIE_TPH
+ bool "TLP Processing Hints"
+ default n
+ help
+ This option adds support for PCIE TLP Processing Hints (TPH).
+ TPH allows endpoint devices to provide optimization hints, such as
+ desired caching behavior, for requests that target memory space.
+ These hints, called steering tags, can empower the system hardware
+ to optimize the utilization of platform resources.
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 6461aa93fe76..3542b42ea0b9 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_PCIE_PME) += pme.o
obj-$(CONFIG_PCIE_DPC) += dpc.o
obj-$(CONFIG_PCIE_PTM) += ptm.o
obj-$(CONFIG_PCIE_EDR) += edr.o
+obj-$(CONFIG_PCIE_TPH) += tph.o
diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c
new file mode 100644
index 000000000000..5f0cc06b74bb
--- /dev/null
+++ b/drivers/pci/pcie/tph.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TPH (TLP Processing Hints) support
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ * Eric Van Tassell <Eric.VanTassell@amd.com>
+ * Wei Huang <wei.huang2@amd.com>
+ */
+
+#define pr_fmt(fmt) "TPH: " fmt
+#define dev_fmt pr_fmt
+
+#include <linux/acpi.h>
+#include <uapi/linux/pci_regs.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/msi.h>
+#include <linux/pci.h>
+#include <linux/msi.h>
+#include <linux/pci-acpi.h>
+
+#include "../pci.h"
+
+void pcie_tph_init(struct pci_dev *dev)
+{
+ dev->tph_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_TPH);
+}
+
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 15168881ec94..1f1ae55a5f83 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2484,6 +2484,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
pci_dpc_init(dev); /* Downstream Port Containment */
pci_rcec_init(dev); /* Root Complex Event Collector */
pci_doe_init(dev); /* Data Object Exchange */
+ pcie_tph_init(dev); /* TLP Processing Hints */

pcie_report_downtraining(dev);
pci_init_reset_methods(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5bece7fd11f8..d75a88ec5136 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -530,6 +530,10 @@ struct pci_dev {

/* These methods index pci_reset_fn_methods[] */
u8 reset_methods[PCI_NUM_RESET_METHODS]; /* In priority order */
+
+#ifdef CONFIG_PCIE_TPH
+ u16 tph_cap; /* TPH capability offset */
+#endif
};

static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
--
2.44.0