thunderbolt: Add DMA traffic test driver
This driver allows sending DMA traffic over XDomain connection.
Specifically over a loopback connection using either a Thunderbolt/USB4
cable that is connected back to the host router port, or a special
loopback dongle that has RX and TX lines crossed. This can be useful at
manufacturing floor to check whether Thunderbolt/USB4 ports are
functional.
The driver exposes debugfs directory under the XDomain service that can
be used to configure the driver, start the test and check the results.
If a loopback dongle is used the steps to send and receive 1000 packets
can be done like:
# modprobe thunderbolt_dma_test
# echo 1000 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/packets_to_receive
# echo 1000 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/packets_to_send
# echo 1 > /sys/kernel/debug/thunderbolt/<service_id>/dma_test/test
# cat /sys/kernel/debug/thunderbolt/<service_id>/dma_test/status
When a cable is connected back to host then there are two Thunderbolt
services, one is configured for receiving (does not matter which one):
# modprobe thunderbolt_dma_test
# echo 1000 > /sys/kernel/debug/thunderbolt/<service_a>/dma_test/packets_to_receive
# echo 1 > /sys/kernel/debug/thunderbolt/<service_a>/dma_test/test
The other one for sending:
# echo 1000 > /sys/kernel/debug/thunderbolt/<service_b>/dma_test/packets_to_send
# echo 1 > /sys/kernel/debug/thunderbolt/<service_b>/dma_test/test
Results can be read from both services status attributes.
Signed-off-by: Isaac Hazan <isaac.hazan@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/thunderbolt/Kconfig b/drivers/thunderbolt/Kconfig
index 7fc058f..4bfec8a 100644
--- a/drivers/thunderbolt/Kconfig
+++ b/drivers/thunderbolt/Kconfig
@@ -31,4 +31,17 @@
bool "KUnit tests"
depends on KUNIT=y
+config USB4_DMA_TEST
+ tristate "DMA traffic test driver"
+ depends on DEBUG_FS
+ help
+ This allows sending and receiving DMA traffic through loopback
+ connection. Loopback connection can be done by either special
+ dongle that has TX/RX lines crossed, or by simply connecting a
+ cable back to the host. Only enable this if you know what you
+ are doing. Normal users and distro kernels should say N here.
+
+ To compile this driver a module, choose M here. The module will be
+ called thunderbolt_dma_test.
+
endif # USB4
