sandbox: add dummy driver ETH_SANDBOX_LWIP

Introduce ETH_SANDBOX_LWIP which enables a mock driver similar to
ETH_SANDOX but without the dependencies on the legacy network stack
(NET) so that it may be enabled when the lwIP stack (NET_LWIP) is
introduced. The driver does nothing at this stage but its presence
will allow dm_test_iommu_noiommu [1] to pass.

[1] ./u-boot -T -c "ut dm dm_test_iommu_noiommu"

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/net/Kconfig

@@ -350,6 +350,17 @@ config ETH_SANDBOX
 
 	  This driver is particularly useful in the test/dm/eth.c tests
 
+config ETH_SANDBOX_LWIP
+	depends on SANDBOX
+	depends on NET_LWIP
+	default y
+	bool "Sandbox: Mocked Ethernet driver (for NET_LWIP)"
+	help
+	  This driver is meant as a replacement for ETH_SANDBOX when
+	  the network stack is NET_LWIP rather than NET. It currently
+	  does nothing, i.e. it drops the sent packets and never receives
+	  data.
+
 config ETH_SANDBOX_RAW
 	depends on SANDBOX
 	default y

drivers/net/Makefile

@@ -39,6 +39,7 @@ obj-$(CONFIG_ETH_DESIGNWARE_SOCFPGA) += dwmac_socfpga.o
 obj-$(CONFIG_ETH_SANDBOX) += sandbox.o
 obj-$(CONFIG_ETH_SANDBOX_RAW) += sandbox-raw-bus.o
 obj-$(CONFIG_ETH_SANDBOX_RAW) += sandbox-raw.o
+obj-$(CONFIG_ETH_SANDBOX_LWIP) += sandbox-lwip.o
 obj-$(CONFIG_FEC_MXC) += fec_mxc.o
 obj-$(CONFIG_FMAN_ENET) += fm/
 obj-$(CONFIG_FMAN_ENET) += fsl_mdio.o

drivers/net/sandbox-lwip.c

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015 National Instruments
+ *
+ * (C) Copyright 2015
+ * Joe Hershberger <joe.hershberger@ni.com>
+ */
+
+#include <dm.h>
+#include <log.h>
+#include <malloc.h>
+#include <net.h>
+#include <asm/eth.h>
+#include <asm/global_data.h>
+#include <asm/test.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int sb_lwip_eth_start(struct udevice *dev)
+{
+	debug("eth_sandbox_lwip: Start\n");
+
+	return 0;
+}
+
+static int sb_lwip_eth_send(struct udevice *dev, void *packet, int length)
+{
+	debug("eth_sandbox_lwip: Send packet %d\n", length);
+
+	return -ENOTSUPP;
+}
+
+static int sb_lwip_eth_recv(struct udevice *dev, int flags, uchar **packetp)
+{
+	return -EAGAIN;
+}
+
+static int sb_lwip_eth_free_pkt(struct udevice *dev, uchar *packet, int length)
+{
+	return 0;
+}
+
+static void sb_lwip_eth_stop(struct udevice *dev)
+{
+}
+
+static int sb_lwip_eth_write_hwaddr(struct udevice *dev)
+{
+	return 0;
+}
+
+static const struct eth_ops sb_eth_ops = {
+	.start			= sb_lwip_eth_start,
+	.send			= sb_lwip_eth_send,
+	.recv			= sb_lwip_eth_recv,
+	.free_pkt		= sb_lwip_eth_free_pkt,
+	.stop			= sb_lwip_eth_stop,
+	.write_hwaddr		= sb_lwip_eth_write_hwaddr,
+};
+
+static int sb_lwip_eth_remove(struct udevice *dev)
+{
+	return 0;
+}
+
+static int sb_lwip_eth_of_to_plat(struct udevice *dev)
+{
+	return 0;
+}
+
+static const struct udevice_id sb_eth_ids[] = {
+	{ .compatible = "sandbox,eth" },
+	{ }
+};
+
+U_BOOT_DRIVER(eth_sandbox) = {
+	.name	= "eth_lwip_sandbox",
+	.id	= UCLASS_ETH,
+	.of_match = sb_eth_ids,
+	.of_to_plat = sb_lwip_eth_of_to_plat,
+	.remove	= sb_lwip_eth_remove,
+	.ops	= &sb_eth_ops,
+	.priv_auto	= 0,
+	.plat_auto	= sizeof(struct eth_pdata),
+};