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

[Kishon Vijay Abraham I]

Hi Randy,

On 06/09/20 3:38 am, Randy Dunlap wrote:
> 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@xxxxxx>
>> ---
>>  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:

Thanks for reviewing. I'll fix and post a new revision.

Thanks
Kishon

> 
> 
>> 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@xxxxxx>
>> +
>> +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.
>