Re: [PATCH v3 17/17] Documentation: PCI: Add userguide for PCI endpoint NTB function

From: Randy Dunlap <rdunlap@infradead.org>
To: Kishon Vijay Abraham I <kishon@ti.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Jon Mason <jdmason@kudzu.us>, Dave Jiang <dave.jiang@intel.com>,
	Allen Hubbe <allenbh@gmail.com>, Rob Herring <robh@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Tom Joseph <tjoseph@cadence.com>,
	linux-pci@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-ntb@googlegroups.com
Subject: Re: [PATCH v3 17/17] Documentation: PCI: Add userguide for PCI endpoint NTB function
Date: Sat, 5 Sep 2020 15:08:12 -0700	[thread overview]
Message-ID: <f16f5a90-13c1-bfc6-ad83-1c6becbf1629@infradead.org> (raw)
In-Reply-To: <20200904075052.8911-18-kishon@ti.com>

On 9/4/20 12:50 AM, Kishon Vijay Abraham I wrote:
> Add documentation to help users use pci-epf-ntb function driver and
> existing host side NTB infrastructure for NTB functionality.
> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
>  Documentation/PCI/endpoint/index.rst         |   1 +
>  Documentation/PCI/endpoint/pci-ntb-howto.rst | 160 +++++++++++++++++++
>  2 files changed, 161 insertions(+)
>  create mode 100644 Documentation/PCI/endpoint/pci-ntb-howto.rst

Hi,
There are a few edits below:

> diff --git a/Documentation/PCI/endpoint/pci-ntb-howto.rst b/Documentation/PCI/endpoint/pci-ntb-howto.rst
> new file mode 100644
> index 000000000000..2fbb0a051c3b
> --- /dev/null
> +++ b/Documentation/PCI/endpoint/pci-ntb-howto.rst
> @@ -0,0 +1,160 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +======================
> +PCI NTB EPF User Guide
> +======================
> +
> +:Author: Kishon Vijay Abraham I <kishon@ti.com>
> +
> +This document is a guide to help users use pci-epf-ntb function driver
> +and ntb_hw_epf host driver for NTB functionality. The list of steps to
> +be followed in the host side and EP side is given below. For the hardware
> +configuration and internals of NTB using configurable endpoints see
> +Documentation/PCI/endpoint/pci-ntb-function.rst
> +
> +Endpoint Device
> +===============
> +
> +Endpoint Controller Devices
> +---------------------------
> +
> +For implementing NTB functionality atleast two endpoint controller devices

                                      at least

> +are required.
> +To find the list of endpoint controller devices in the system::
> +
> +        # ls /sys/class/pci_epc/
> +          2900000.pcie-ep  2910000.pcie-ep
> +
> +If PCI_ENDPOINT_CONFIGFS is enabled::
> +
> +	# ls /sys/kernel/config/pci_ep/controllers
> +	  2900000.pcie-ep  2910000.pcie-ep
> +
> +
> +Endpoint Function Drivers
> +-------------------------
> +
> +To find the list of endpoint function drivers in the system::
> +
> +	# ls /sys/bus/pci-epf/drivers
> +	  pci_epf_ntb   pci_epf_ntb
> +
> +If PCI_ENDPOINT_CONFIGFS is enabled::
> +
> +	# ls /sys/kernel/config/pci_ep/functions
> +	  pci_epf_ntb   pci_epf_ntb
> +
> +
> +Creating pci-epf-ntb Device
> +----------------------------
> +
> +PCI endpoint function device can be created using the configfs. To create
> +pci-epf-ntb device, the following commands can be used::
> +
> +	# mount -t configfs none /sys/kernel/config
> +	# cd /sys/kernel/config/pci_ep/
> +	# mkdir functions/pci_epf_ntb/func1
> +
> +The "mkdir func1" above creates the pci-epf-ntb function device that will
> +be probed by pci_epf_ntb driver.
> +
> +The PCI endpoint framework populates the directory with the following
> +configurable fields::
> +
> +	# ls functions/pci_epf_ntb/func1
> +          baseclass_code    deviceid          msi_interrupts    pci-epf-ntb.0
> +          progif_code       secondary         subsys_id         vendorid
> +          cache_line_size   interrupt_pin     msix_interrupts   primary
> +          revid             subclass_code     subsys_vendor_id
> +
> +The PCI endpoint function driver populates these entries with default values
> +when the device is bound to the driver. The pci-epf-ntb driver populates
> +vendorid with 0xffff and interrupt_pin with 0x0001::
> +
> +	# cat functions/pci_epf_ntb/func1/vendorid
> +	  0xffff
> +	# cat functions/pci_epf_ntb/func1/interrupt_pin
> +	  0x0001
> +
> +
> +Configuring pci-epf-ntb Device
> +-------------------------------
> +
> +The user can configure the pci-epf-ntb device using configfs entry. In order

                                                 using its configfs entry.

> +to change the vendorid and the deviceid, the following
> +commands can be used::
> +
> +	# echo 0x104c > functions/pci_epf_ntb/func1/vendorid
> +	# echo 0xb00d > functions/pci_epf_ntb/func1/deviceid
> +
> +In-order to configure NTB specific attributes, a new sub-directory to func1

   In order

> +should be created::
> +
> +	# mkdir functions/pci_epf_ntb/func1/pci_epf_ntb.0/
> +
> +The NTB function driver will populate this directory with various attributes
> +that can be configured by the user::
> +
> +	# ls functions/pci_epf_ntb/func1/pci_epf_ntb.0/
> +          db_count    mw1         mw2         mw3         mw4         num_mws
> +          spad_count
> +
> +A sample configuration for NTB function is given below::
> +
> +	# echo 4 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/db_count
> +	# echo 128 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/spad_count
> +	# echo 2 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/num_mws
> +	# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw1
> +	# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw2
> +
> +Binding pci-epf-ntb Device to EP Controller
> +--------------------------------------------
> +
> +NTB function device should be attached to two PCIe endpoint controllers
> +connected to the two hosts. Use the 'primary' and 'secondary' entries
> +inside NTB function device to attach one PCIe endpoint controller to
> +primary interface and the other PCIe endpoint controller to the secondary
> +interface. ::
> +
> +        # ln -s controllers/2900000.pcie-ep/ functions/pci-epf-ntb/func1/primary
> +        # ln -s controllers/2910000.pcie-ep/ functions/pci-epf-ntb/func1/secondary
> +
> +Once the above step is completed, both the PCI endpoint controllers is ready to

                                                                       are ready

> +establish a link with the host.
> +
> +
> +Start the Link
> +--------------
> +
> +In order for the endpoint device to establish a link with the host, the _start_
> +field should be populated with '1'. For NTB, both the PCIe endpoint controllers
> +should establish link with the host::
> +
> +        #echo 1 > controllers/2900000.pcie-ep/start
> +        #echo 1 > controllers/2910000.pcie-ep/start
> +
> +
> +RootComplex Device
> +==================
> +
> +lspci Output
> +------------
> +
> +Note that the devices listed here correspond to the value populated in 1.4

Can you use a section name (or reference) here instead of "1.4"?  I can't see 1.4
when reading with an editor.

> +above::
> +
> +        # lspci
> +        0000:00:00.0 PCI bridge: Texas Instruments Device b00d
> +        0000:01:00.0 RAM memory: Texas Instruments Device b00d
> +
> +
> +Using ntb_hw_epf Device
> +-----------------------
> +
> +The host side software follows the standard NTB software architecture in Linux.
> +All the existing client side NTB utilities like NTB Transport Client and NTB
> +Netdev, NTB Ping Pong Test Client and NTB Tool Test Clientcan be used with NTB

                                                       Client can be

> +function device.
> +
> +For more information on NTB see
> +Documentation/driver-api/ntb.rst

thanks.
-- 
~Randy