NTB: Add ping pong test client

Transport queue pair buffer.  The Transport client may be used for other things

besides Netdev, however no other applications have yet been written.

### NTB Ping Pong Test Client (ntb\_pingpong)

The Ping Pong test client serves as a demonstration to exercise the doorbell

and scratchpad registers of NTB hardware, and as an example simple NTB client.

Ping Pong enables the link when started, waits for the NTB link to come up, and

then proceeds to read and write the doorbell scratchpad registers of the NTB.

The peers interrupt each other using a bit mask of doorbell bits, which is

shifted by one in each round, to test the behavior of multiple doorbell bits

and interrupt vectors.  The Ping Pong driver also reads the first local

scratchpad, and writes the value plus one to the first peer scratchpad, each

round before writing the peer doorbell register.

Module Parameters:

* unsafe - Some hardware has known issues with scratchpad and doorbell

	registers.  By default, Ping Pong will not attempt to exercise such

	hardware.  You may override this behavior at your own risk by setting

	unsafe=1.

* delay\_ms - Specify the delay between receiving a doorbell

	interrupt event and setting the peer doorbell register for the next

	round.

* init\_db - Specify the doorbell bits to start new series of rounds.  A new

	series begins once all the doorbell bits have been shifted out of

	range.

* dyndbg - It is suggested to specify dyndbg=+p when loading this module, and

	then to observe debugging output on the console.

## NTB Hardware Drivers

NTB hardware drivers should register devices with the NTB core driver.  After

source "drivers/ntb/hw/Kconfig"

source "drivers/ntb/test/Kconfig"

config NTB_TRANSPORT

	tristate "NTB Transport Client"

	help

obj-$(CONFIG_NTB) += ntb.o hw/

obj-$(CONFIG_NTB) += ntb.o hw/ test/

obj-$(CONFIG_NTB_TRANSPORT) += ntb_transport.o

config NTB_PINGPONG

	tristate "NTB Ping Pong Test Client"

	help

	 This is a simple ping pong driver that exercises the scratchpads and

	 doorbells of the ntb hardware.  This driver may be used to test that

	 your ntb hardware and drivers are functioning at a basic level.

	 If unsure, say N.

obj-$(CONFIG_NTB_PINGPONG) += ntb_pingpong.o