Add selftest case to check the send and receive throughput.
Supported link modes between local NIC driver and partner
are varied. Then send and receive throughput is captured
and verified. Test uses iperf3 tool.

Signed-off-by: Mohan Prasad J <mohan.prasad@microchip.com>
---
 .../drivers/net/hw/nic_basic_tests.py         | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/hw/nic_basic_tests.py b/tools/testing/selftests/drivers/net/hw/nic_basic_tests.py
index ff46f2406..ec1f5b6a2 100644
--- a/tools/testing/selftests/drivers/net/hw/nic_basic_tests.py
+++ b/tools/testing/selftests/drivers/net/hw/nic_basic_tests.py
@@ -182,6 +182,45 @@ def test_network_speed(cfg) -> None:
         else:
             KsftSkipEx("Mismatch in the number of speeds and duplex modes")
 
+def test_tcp_throughput(cfg) -> None:
+    check_autonegotiation(cfg.ifname)
+    if not common_link_modes:
+        KsftSkipEx("No common link modes found")
+    cfg.require_cmd("iperf3", remote=True)
+    """iperf3 server to be run in the partner pc"""
+    speeds, duplex_modes = get_speed_duplex(common_link_modes)
+    """Test duration in seconds"""
+    duration = test_duration
+    target_ip = cfg.remote_addr
+
+    for idx in range(len(speeds)-1, -1, -1):
+        set_speed_and_duplex(cfg.ifname, speeds[idx], duplex_modes[idx])
+        time.sleep(sleep_time)
+        verify_link_up(cfg.ifname)
+        send_command=f"iperf3 -c {target_ip} -t {duration} --json"
+        receive_command=f"iperf3 -c {target_ip} -t {duration} --reverse --json"
+        send_result = cmd(send_command)
+        receive_result = cmd(receive_command)
+        if send_result.ret != 0 or receive_result.ret != 0:
+            raise KsftSkipEx("No server is running")
+
+        send_output = send_result.stdout
+        receive_output = receive_result.stdout
+
+        send_data = json.loads(send_output)
+        receive_data = json.loads(receive_output)
+        """Convert throughput to Mbps"""
+        send_throughput = round(send_data['end']['sum_sent']['bits_per_second'] / 1e6, 2)
+        receive_throughput = round(receive_data['end']['sum_received']['bits_per_second'] / 1e6, 2)
+
+        ksft_pr(f"Send throughput: {send_throughput} Mbps, Receive throughput: {receive_throughput} Mbps")
+        """Check whether throughput is not below the threshold (default:80% of set speed)"""
+        threshold = float(speeds[idx]) * float(throughput_threshold)
+        if send_throughput < threshold:
+            raise KsftFailEx("Send throughput is below threshold")
+        elif receive_throughput < threshold:
+            raise KsftFailEx("Receive throughput is below threshold")
+
 def main() -> None:
     with NetDrvEpEnv(__file__) as cfg:
         ksft_run(globs=globals(), case_pfx={"test_"}, args=(cfg,))
-- 
2.43.0