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[V2,7/9] PCI/TPH: Add TPH documentation

Message ID 20240531213841.3246055-8-wei.huang2@amd.com (mailing list archive)
State Not Applicable
Headers show
Series PCIe TPH and cache direct injection support | expand

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Commit Message

Wei Huang May 31, 2024, 9:38 p.m. UTC
Provide a document for TPH feature, including the description of
kernel options and driver API interface.

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>
---
 Documentation/PCI/index.rst          |  1 +
 Documentation/PCI/tph.rst            | 57 ++++++++++++++++++++++++++++
 Documentation/driver-api/pci/pci.rst |  3 ++
 3 files changed, 61 insertions(+)
 create mode 100644 Documentation/PCI/tph.rst

Comments

Jonathan Cameron June 7, 2024, 5:43 p.m. UTC | #1
On Fri, 31 May 2024 16:38:39 -0500
Wei Huang <wei.huang2@amd.com> wrote:

> Provide a document for TPH feature, including the description of
> kernel options and driver API interface.
> 
> 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>
Sort and sweet.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  Documentation/PCI/index.rst          |  1 +
>  Documentation/PCI/tph.rst            | 57 ++++++++++++++++++++++++++++
>  Documentation/driver-api/pci/pci.rst |  3 ++
>  3 files changed, 61 insertions(+)
>  create mode 100644 Documentation/PCI/tph.rst
> 
> diff --git a/Documentation/PCI/index.rst b/Documentation/PCI/index.rst
> index e73f84aebde3..5e7c4e6e726b 100644
> --- a/Documentation/PCI/index.rst
> +++ b/Documentation/PCI/index.rst
> @@ -18,3 +18,4 @@ PCI Bus Subsystem
>     pcieaer-howto
>     endpoint/index
>     boot-interrupts
> +   tph
> diff --git a/Documentation/PCI/tph.rst b/Documentation/PCI/tph.rst
> new file mode 100644
> index 000000000000..ea9c8313f3e4
> --- /dev/null
> +++ b/Documentation/PCI/tph.rst
> @@ -0,0 +1,57 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +===========
> +TPH Support
> +===========
> +
> +
> +:Copyright: 2024 Advanced Micro Devices, Inc.
> +:Authors: - Eric van Tassell <eric.vantassell@amd.com>
> +          - Wei Huang <wei.huang2@amd.com>
> +
> +Overview
> +========
> +TPH (TLP Processing Hints) is a PCIe feature that allows endpoint devices
> +to provide optimization hints, such as desired caching behavior, for
> +requests that target memory space. These hints, in a format called steering
> +tags, are provided in the requester's TLP headers and can empower the system
> +hardware, including the Root Complex, to optimize the utilization of platform
> +resources for the requests.
> +
> +User Guide
> +==========
> +
> +Kernel Options
> +--------------
> +There are two kernel command line options available to control TPH feature
> +
> +   * "notph": TPH will be disabled for all endpoint devices.
> +   * "nostmode": TPH will be enabled but the ST Mode will be forced to "No ST Mode".
> +
> +Device Driver API
> +-----------------
> +In brief, an endpoint device driver using the TPH interface to configure
> +Interrupt Vector Mode will call pcie_tph_set_st() when setting up MSI-X
> +interrupts as shown below:
> +
> +.. code-block:: c
> +
> +    for (i = 0, j = 0; i < nr_rings; i++) {
> +        ...
> +        rc = request_irq(irq->vector, irq->handler, flags, irq->name, NULL);
> +        ...
> +        if (!pcie_tph_set_st(pdev, i, cpumask_first(irq->cpu_mask),
> +                             TPH_MEM_TYPE_VM, PCI_TPH_REQ_TPH_ONLY))
> +               pr_err("Error in configuring steering tag\n");
> +        ...
> +    }
> +
> +If a device only supports TPH vendor specific mode, its driver can call
> +pcie_tph_get_st() to retrieve the steering tag for a specific CPU and uses
> +the tag to control TPH behavior.
> +
> +.. kernel-doc:: drivers/pci/pcie/tph.c
> +   :export:
> +
> +.. kernel-doc:: drivers/pci/pcie/tph.c
> +   :identifiers: pcie_tph_set_st
> diff --git a/Documentation/driver-api/pci/pci.rst b/Documentation/driver-api/pci/pci.rst
> index aa40b1cc243b..3d896b2cf16e 100644
> --- a/Documentation/driver-api/pci/pci.rst
> +++ b/Documentation/driver-api/pci/pci.rst
> @@ -46,6 +46,9 @@ PCI Support Library
>  .. kernel-doc:: drivers/pci/pci-sysfs.c
>     :internal:
>  
> +.. kernel-doc:: drivers/pci/pcie/tph.c
> +   :export:
> +
>  PCI Hotplug Support Library
>  ---------------------------
>
diff mbox series

Patch

diff --git a/Documentation/PCI/index.rst b/Documentation/PCI/index.rst
index e73f84aebde3..5e7c4e6e726b 100644
--- a/Documentation/PCI/index.rst
+++ b/Documentation/PCI/index.rst
@@ -18,3 +18,4 @@  PCI Bus Subsystem
    pcieaer-howto
    endpoint/index
    boot-interrupts
+   tph
diff --git a/Documentation/PCI/tph.rst b/Documentation/PCI/tph.rst
new file mode 100644
index 000000000000..ea9c8313f3e4
--- /dev/null
+++ b/Documentation/PCI/tph.rst
@@ -0,0 +1,57 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+===========
+TPH Support
+===========
+
+
+:Copyright: 2024 Advanced Micro Devices, Inc.
+:Authors: - Eric van Tassell <eric.vantassell@amd.com>
+          - Wei Huang <wei.huang2@amd.com>
+
+Overview
+========
+TPH (TLP Processing Hints) is a PCIe feature that allows endpoint devices
+to provide optimization hints, such as desired caching behavior, for
+requests that target memory space. These hints, in a format called steering
+tags, are provided in the requester's TLP headers and can empower the system
+hardware, including the Root Complex, to optimize the utilization of platform
+resources for the requests.
+
+User Guide
+==========
+
+Kernel Options
+--------------
+There are two kernel command line options available to control TPH feature
+
+   * "notph": TPH will be disabled for all endpoint devices.
+   * "nostmode": TPH will be enabled but the ST Mode will be forced to "No ST Mode".
+
+Device Driver API
+-----------------
+In brief, an endpoint device driver using the TPH interface to configure
+Interrupt Vector Mode will call pcie_tph_set_st() when setting up MSI-X
+interrupts as shown below:
+
+.. code-block:: c
+
+    for (i = 0, j = 0; i < nr_rings; i++) {
+        ...
+        rc = request_irq(irq->vector, irq->handler, flags, irq->name, NULL);
+        ...
+        if (!pcie_tph_set_st(pdev, i, cpumask_first(irq->cpu_mask),
+                             TPH_MEM_TYPE_VM, PCI_TPH_REQ_TPH_ONLY))
+               pr_err("Error in configuring steering tag\n");
+        ...
+    }
+
+If a device only supports TPH vendor specific mode, its driver can call
+pcie_tph_get_st() to retrieve the steering tag for a specific CPU and uses
+the tag to control TPH behavior.
+
+.. kernel-doc:: drivers/pci/pcie/tph.c
+   :export:
+
+.. kernel-doc:: drivers/pci/pcie/tph.c
+   :identifiers: pcie_tph_set_st
diff --git a/Documentation/driver-api/pci/pci.rst b/Documentation/driver-api/pci/pci.rst
index aa40b1cc243b..3d896b2cf16e 100644
--- a/Documentation/driver-api/pci/pci.rst
+++ b/Documentation/driver-api/pci/pci.rst
@@ -46,6 +46,9 @@  PCI Support Library
 .. kernel-doc:: drivers/pci/pci-sysfs.c
    :internal:
 
+.. kernel-doc:: drivers/pci/pcie/tph.c
+   :export:
+
 PCI Hotplug Support Library
 ---------------------------