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Date: Thu, 14 Oct 2021 10:21:22 +0800
From: Xu Yilun <yilun.xu@...el.com>
To: Lizhi Hou <lizhi.hou@...inx.com>
Cc: linux-kernel@...r.kernel.org, linux-fpga@...r.kernel.org,
maxz@...inx.com, sonal.santan@...inx.com, yliu@...inx.com,
michal.simek@...inx.com, stefanos@...inx.com,
devicetree@...r.kernel.org, trix@...hat.com, mdf@...nel.org,
robh@...nel.org, Max Zhen <max.zhen@...inx.com>
Subject: Re: [PATCH V9 XRT Alveo 01/14] Documentation: fpga: Add a document
describing XRT Alveo drivers
> > > +.. _device_tree_usage:
> > > +
> > > +Device Tree Usage
> > > +-----------------
> > > +
> > > +The xsabin file stores metadata which advertise HW subsystems present in a
> > > +partition. The metadata is stored in device tree format with a well defined
> > > +schema. XRT management driver uses this information to bind *xrt_drivers* to
> > > +the subsystem instantiations. The xrt_drivers are found in **xrt-lib.ko** kernel
> > > +module.
> > I'm still catching up the patchset from the very beginning, and just
> > finished the Documentation part. So far, I see the DT usage concern
> > which may impact the architecure a lot, so I should raise it ASAP.
> >
> > The concern raised by the DT maintainer:
> > https://lore.kernel.org/linux-fpga/CAL_JsqLod6FBGFhu7WXtMrB_z7wj8-up0EetM1QS9M3gjm8d7Q@mail.gmail.com/
> >
> > First of all, directly parsing FDT in device drivers is not a normal usage of DT
> > in linux. It is out of the current DT usage model. So it should be agreed by DT
> > maintainers.
> Thanks for reviewing XRT document and providing feedback.
> Here is the reply from Sonal for Rob’s question:
> https://lore.kernel.org/linux-fpga/BY5PR02MB62604B87C66A1AD139A6F153BBF40@BY5PR02MB6260.namprd02.prod.outlook.com/
> Overall, libfdt is used by XRT driver to parse the metadata which comes with
> an Alveo board.
> When XRT driver discovers an Alveo board, it will read a fdt blob from board
> firmware file resident on the host.
> By parsing the fdt blob, XRT driver gets information about this Alveo board,
> such as version, uuid, IPs exposed to PCI BAR, interrupt binding etc.
> So libfdt is used simply as Alveo metadata parser here. XRT drivers do not
> interact with system wide DT or present the Alveo device tree to host. For
> many systems like x86_64, system wide DT is not present but libfdt parsing
> services will still be needed.
Yes, I understand the use case.
My concern is, directly parsing an isolated FDT in device driver and
populate sub devices, skipping the unflattening, this is a new working
model of device tree usage, but for the same purpose as the existing
one.
So I really need the confirmation of DT maintainers.
> >
> > Current FPGA framework modifies kernel's live tree by DT overlay, when FPGA is
> > dynamically reprogrammed and new HW devices appear. See
> > Documentation/devicetree/bindings/fpga/fpga-region.txt.
> >
> > Then something less important:
> >
> > 1. The bindings should be documented in Documentation/devicetree/bindings/.
> > 2. Are all the example DT usage conform to the exsiting bindings? I
> > didn't go through all device classes, but remember like the
> > interrupt-controller should have a "interrupt-controller" property, and
> > the PCI properties are also different from PCI bindings.
>
> The fdt properties are defined for Alveo firmware files. XRT driver is the
> only consumer of this data. I am wondering if
Personally I don't like the idea of a different binding definition set,
even if the new device tree usage is accepted. We all use device tree
for device enumeration, so why the different definitions.
Thanks,
Yilun
> Documentation/devicetree/bindings is the right place for Alveo/XRT private
> format or should it be documented as part of XRT driver documentation?
> Looking for guidance here.
>
>
> Thanks,
>
> Lizhi
>
> >
> > Thanks,
> > Yilun
> >
> > > +
> > > +Logic UUID
> > > +^^^^^^^^^^
> > > +A partition is identified uniquely through ``logic_uuid`` property::
> > > +
> > > + /dts-v1/;
> > > + / {
> > > + logic_uuid = "0123456789abcdef0123456789abcdef";
> > > + ...
> > > + }
> > > +
> > > +Schema Version
> > > +^^^^^^^^^^^^^^
> > > +Schema version is defined through the ``schema_version`` node. It contains
> > > +``major`` and ``minor`` properties as below::
> > > +
> > > + /dts-v1/;
> > > + / {
> > > + schema_version {
> > > + major = <0x01>;
> > > + minor = <0x00>;
> > > + };
> > > + ...
> > > + }
> > > +
> > > +.. _partition_uuids:
> > > +
> > > +Partition UUIDs
> > > +^^^^^^^^^^^^^^^
> > > +Each partition may have parent and child UUIDs. These UUIDs are
> > > +defined by ``interfaces`` node and ``interface_uuid`` property::
> > > +
> > > + /dts-v1/;
> > > + / {
> > > + interfaces {
> > > + @0 {
> > > + interface_uuid = "0123456789abcdef0123456789abcdef";
> > > + };
> > > + @1 {
> > > + interface_uuid = "fedcba9876543210fedcba9876543210";
> > > + };
> > > + ...
> > > + };
> > > + ...
> > > + }
> > > +
> > > +
> > > +Subsystem Instantiations
> > > +^^^^^^^^^^^^^^^^^^^^^^^^
> > > +Subsystem instantiations are captured as children of ``addressable_endpoints``
> > > +node::
> > > +
> > > + /dts-v1/;
> > > + / {
> > > + addressable_endpoints {
> > > + abc {
> > > + ...
> > > + };
> > > + def {
> > > + ...
> > > + };
> > > + ...
> > > + }
> > > + }
> > > +
> > > +Subnode 'abc' and 'def' are the name of subsystem nodes
> > > +
> > > +Subsystem Node
> > > +^^^^^^^^^^^^^^
> > > +Each subsystem node and its properties define a hardware instance::
> > > +
> > > +
> > > + addressable_endpoints {
> > > + abc {
> > > + reg = <0x00 0x1f05000 0x00 0x1000>>
> > > + pcie_physical_function = <0x0>;
> > > + pcie_bar_mapping = <0x2>;
> > > + compatible = "abc def";
> > > + interrupts = <0x09 0x0c>;
> > > + firmware {
> > > + firmware_product_name = "abc"
> > > + firmware_branch_name = "def"
> > > + firmware_version_major = <1>
> > > + firmware_version_minor = <2>
> > > + };
> > > + }
> > > + ...
> > > + }
> > > +
> > > +:reg:
> > > + Property defines an address range. `<0x00 0x1f05000 0x00 0x1000>` indicates
> > > + *0x00 0x1f05000* as BAR offset and *0x00 0x1000* as address length.
> > > +:pcie_physical_function:
> > > + Property specifies which PCIe physical function the subsystem node resides.
> > > + `<0x0>` implies physical function 0.
> > > +:pcie_bar_mapping:
> > > + Property specifies which PCIe BAR the subsystem node resides. `<0x2>` implies
> > > + BAR 2. A value of 0 means the property is not defined.
> > > +:compatible:
> > > + Property is a list of strings. The first string in the list specifies the exact
> > > + subsystem node. The following strings represent other devices that the device
> > > + is compatible with.
> > > +:interrupts:
> > > + Property specifies start and end interrupts for this subsystem node.
> > > + `<0x09 0x0c>` implies interrupts 9 to 13 are used by this subsystem.
> > > +:firmware:
> > > + Subnode defines the firmware required by this subsystem node.
> > > +
> > > +Alveo U50 Platform Example
> > > +^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > +::
> > > +
> > > + /dts-v1/;
> > > +
> > > + /{
> > > + logic_uuid = "f465b0a3ae8c64f619bc150384ace69b";
> > > +
> > > + schema_version {
> > > + major = <0x01>;
> > > + minor = <0x00>;
> > > + };
> > > +
> > > + interfaces {
> > > +
> > > + @0 {
> > > + interface_uuid = "862c7020a250293e32036f19956669e5";
> > > + };
> > > + };
> > > +
> > > + addressable_endpoints {
> > > +
> > > + ep_blp_rom_00 {
> > > + reg = <0x00 0x1f04000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > + };
> > > +
> > > + ep_card_flash_program_00 {
> > > + reg = <0x00 0x1f06000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_quad_spi-1.0\0axi_quad_spi";
> > > + interrupts = <0x03 0x03>;
> > > + };
> > > +
> > > + ep_cmc_firmware_mem_00 {
> > > + reg = <0x00 0x1e20000 0x00 0x20000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "cmc";
> > > + firmware_branch_name = "u50";
> > > + firmware_version_major = <0x01>;
> > > + firmware_version_minor = <0x00>;
> > > + };
> > > + };
> > > +
> > > + ep_cmc_intc_00 {
> > > + reg = <0x00 0x1e03000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_intc-1.0\0axi_intc";
> > > + interrupts = <0x04 0x04>;
> > > + };
> > > +
> > > + ep_cmc_mutex_00 {
> > > + reg = <0x00 0x1e02000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_cmc_regmap_00 {
> > > + reg = <0x00 0x1e08000 0x00 0x2000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "sc-fw";
> > > + firmware_branch_name = "u50";
> > > + firmware_version_major = <0x05>;
> > > + };
> > > + };
> > > +
> > > + ep_cmc_reset_00 {
> > > + reg = <0x00 0x1e01000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ddr_mem_calib_00 {
> > > + reg = <0x00 0x63000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_debug_bscan_mgmt_00 {
> > > + reg = <0x00 0x1e90000 0x00 0x10000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-debug_bridge-1.0\0debug_bridge";
> > > + };
> > > +
> > > + ep_ert_base_address_00 {
> > > + reg = <0x00 0x21000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ert_command_queue_mgmt_00 {
> > > + reg = <0x00 0x40000 0x00 0x10000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-ert_command_queue-1.0\0ert_command_queue";
> > > + };
> > > +
> > > + ep_ert_command_queue_user_00 {
> > > + reg = <0x00 0x40000 0x00 0x10000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-ert_command_queue-1.0\0ert_command_queue";
> > > + };
> > > +
> > > + ep_ert_firmware_mem_00 {
> > > + reg = <0x00 0x30000 0x00 0x8000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > +
> > > + firmware {
> > > + firmware_product_name = "ert";
> > > + firmware_branch_name = "v20";
> > > + firmware_version_major = <0x01>;
> > > + };
> > > + };
> > > +
> > > + ep_ert_intc_00 {
> > > + reg = <0x00 0x23000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_intc-1.0\0axi_intc";
> > > + interrupts = <0x05 0x05>;
> > > + };
> > > +
> > > + ep_ert_reset_00 {
> > > + reg = <0x00 0x22000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_ert_sched_00 {
> > > + reg = <0x00 0x50000 0x00 0x1000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-ert_sched-1.0\0ert_sched";
> > > + interrupts = <0x09 0x0c>;
> > > + };
> > > +
> > > + ep_fpga_configuration_00 {
> > > + reg = <0x00 0x1e88000 0x00 0x8000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_hwicap-1.0\0axi_hwicap";
> > > + interrupts = <0x02 0x02>;
> > > + };
> > > +
> > > + ep_icap_reset_00 {
> > > + reg = <0x00 0x1f07000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_msix_00 {
> > > + reg = <0x00 0x00 0x00 0x20000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-msix-1.0\0msix";
> > > + pcie_bar_mapping = <0x02>;
> > > + };
> > > +
> > > + ep_pcie_link_mon_00 {
> > > + reg = <0x00 0x1f05000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_pr_isolate_plp_00 {
> > > + reg = <0x00 0x1f01000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_pr_isolate_ulp_00 {
> > > + reg = <0x00 0x1000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_gpio-1.0\0axi_gpio";
> > > + };
> > > +
> > > + ep_uuid_rom_00 {
> > > + reg = <0x00 0x64000 0x00 0x1000>;
> > > + pcie_physical_function = <0x00>;
> > > + compatible = "xilinx.com,reg_abs-axi_bram_ctrl-1.0\0axi_bram_ctrl";
> > > + };
> > > +
> > > + ep_xdma_00 {
> > > + reg = <0x00 0x00 0x00 0x10000>;
> > > + pcie_physical_function = <0x01>;
> > > + compatible = "xilinx.com,reg_abs-xdma-1.0\0xdma";
> > > + pcie_bar_mapping = <0x02>;
> > > + };
> > > + };
> > > +
> > > + }
> > > +
> > > +
> > > +
> > > +Deployment Models
> > > +=================
> > > +
> > > +Baremetal
> > > +---------
> > > +
> > > +In bare-metal deployments, both MPF and UPF are visible and accessible. The
> > > +xrt-mgmt driver binds to MPF. The xrt-mgmt driver operations are privileged and
> > > +available to system administrator. The full stack is illustrated below::
> > > +
> > > + HOST
> > > +
> > > + [XRT-MGMT] [XRT-USER]
> > > + | |
> > > + | |
> > > + +-----+ +-----+
> > > + | MPF | | UPF |
> > > + | | | |
> > > + | PF0 | | PF1 |
> > > + +--+--+ +--+--+
> > > + ......... ^................. ^..........
> > > + | |
> > > + | PCIe DEVICE |
> > > + | |
> > > + +--+------------------+--+
> > > + | SHELL |
> > > + | |
> > > + +------------------------+
> > > + | USER |
> > > + | |
> > > + | |
> > > + | |
> > > + | |
> > > + +------------------------+
> > > +
> > > +
> > > +
> > > +Virtualized
> > > +-----------
> > > +
> > > +In virtualized deployments, the privileged MPF is assigned to the host but the
> > > +unprivileged UPF is assigned to a guest VM via PCIe pass-through. The xrt-mgmt
> > > +driver in host binds to MPF. The xrt-mgmt driver operations are privileged and
> > > +only accessible to the MPF. The full stack is illustrated below::
> > > +
> > > +
> > > + ..............
> > > + HOST . VM .
> > > + . .
> > > + [XRT-MGMT] . [XRT-USER] .
> > > + | . | .
> > > + | . | .
> > > + +-----+ . +-----+ .
> > > + | MPF | . | UPF | .
> > > + | | . | | .
> > > + | PF0 | . | PF1 | .
> > > + +--+--+ . +--+--+ .
> > > + ......... ^................. ^..........
> > > + | |
> > > + | PCIe DEVICE |
> > > + | |
> > > + +--+------------------+--+
> > > + | SHELL |
> > > + | |
> > > + +------------------------+
> > > + | USER |
> > > + | |
> > > + | |
> > > + | |
> > > + | |
> > > + +------------------------+
> > > +
> > > +
> > > +
> > > +
> > > +
> > > +Platform Security Considerations
> > > +================================
> > > +
> > > +`Security of Alveo Platform <https://xilinx.github.io/XRT/master/html/security.html>`_
> > > +discusses the deployment options and security implications in great detail.
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 056966c9aac9..beeaf0257364 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -7274,6 +7274,17 @@ F: Documentation/fpga/
> > > F: drivers/fpga/
> > > F: include/linux/fpga/
> > >
> > > +FPGA XRT DRIVERS
> > > +M: Lizhi Hou <lizhi.hou@...inx.com>
> > > +R: Max Zhen <max.zhen@...inx.com>
> > > +R: Sonal Santan <sonal.santan@...inx.com>
> > > +L: linux-fpga@...r.kernel.org
> > > +S: Supported
> > > +W: https://github.com/Xilinx/XRT
> > > +F: Documentation/fpga/xrt.rst
> > > +F: drivers/fpga/xrt/
> > > +F: include/uapi/linux/xrt/
> > > +
> > > FPU EMULATOR
> > > M: Bill Metzenthen <billm@...bpc.org.au>
> > > S: Maintained
> > > --
> > > 2.27.0
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