sandbox: Add a DSA sandbox driver and unit test

The DSA sandbox driver is used for unit testing the DSA class code.
It implements a simple 2 port switch plus 1 CPU port, and uses a
very simple tag to identify the ports.

The DSA sandbox device is connected via CPU port to a regular Ethernet
sandbox device, called 'dsa-test-eth, managed by the existing eth
sandbox driver.  The 'dsa-test-eth' is not intended for testing the
eth class code however, but it is used to emulate traffic through the
'lan0' and 'lan1' front pannel switch ports.  To achieve this the dsa
sandbox driver registers a tx handler for the 'dsa-test-eth' device.
The switch ports, labeled as 'lan0' and 'lan1', are also registered
as eth devices by the dsa class code this time.  So pinging through
these switch ports is as easy as:

=> setenv ethact lan0
=> ping 1.2.3.5

Unit tests for the dsa class code were also added.  The 'dsa_probe'
test exercises most API functions from dsa.h.  The 'dsa' unit test
simply exercises ARP/ICMP traffic through the two switch ports,
including tag injection and extraction, with the help of the dsa
sandbox driver.

I took care to minimize the impact on the existing eth unit tests,
though some adjustments needed to be made with the addition of
extra eth interfaces used by the dsa unit tests. The additional eth
interfaces also require MAC addresses, these have been added to the
sandbox default environment.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Message-Id: <20210216224804.3355044-5-olteanv@gmail.com>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

3 files changed, 189 insertions, 0 deletions

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 54f7b81624..72822eaec4 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -78,6 +78,15 @@ config DM_ETH_PHY
 	help
 	  Enable driver model for Ethernet Generic PHY .
 
+config DSA_SANDBOX
+	depends on DM_DSA && SANDBOX
+	default y
+	bool "Sandbox: Mocked DSA driver"
+	help
+	  This driver implements a dummy DSA switch connected to a dummy sandbox
+	  Ethernet device used as DSA master, to test DSA class code, including
+	  exported DSA API and datapath processing of Ethernet traffic.
+
 menuconfig NETDEVICES
 	bool "Network device support"
 	depends on NET
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index ce7b9e3478..2ce89f7e3c 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_ETH_DESIGNWARE_SOCFPGA) += dwmac_socfpga.o
 obj-$(CONFIG_ETH_DESIGNWARE_S700) += dwmac_s700.o
 obj-$(CONFIG_DRIVER_DM9000) += dm9000x.o
 obj-$(CONFIG_DNET) += dnet.o
+obj-$(CONFIG_DSA_SANDBOX) += dsa_sandbox.o
 obj-$(CONFIG_DM_ETH_PHY) += eth-phy-uclass.o
 obj-$(CONFIG_E1000) += e1000.o
 obj-$(CONFIG_E1000_SPI) += e1000_spi.o
diff --git a/drivers/net/dsa_sandbox.c b/drivers/net/dsa_sandbox.c
new file mode 100644
index 0000000000..4b62670e5d
--- /dev/null
+++ b/drivers/net/dsa_sandbox.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019-2021 NXP Semiconductors
+ */
+
+#include <asm/eth.h>
+#include <net/dsa.h>
+#include <net.h>
+
+#define DSA_SANDBOX_MAGIC	0x00415344
+#define DSA_SANDBOX_TAG_LEN	sizeof(struct dsa_sandbox_tag)
+
+struct dsa_sandbox_priv {
+	struct eth_sandbox_priv *master_priv;
+	int port_en_mask;
+};
+
+struct dsa_sandbox_tag {
+	u32 magic;
+	u32 port;
+};
+
+static bool sb_dsa_port_enabled(struct udevice *dev, int port)
+{
+	struct dsa_sandbox_priv *priv = dev_get_priv(dev);
+
+	return priv->port_en_mask & BIT(port);
+}
+
+static bool sb_dsa_master_enabled(struct udevice *dev)
+{
+	struct dsa_sandbox_priv *priv = dev_get_priv(dev);
+
+	return !priv->master_priv->disabled;
+}
+
+static int dsa_sandbox_port_enable(struct udevice *dev, int port,
+				   struct phy_device *phy)
+{
+	struct dsa_sandbox_priv *priv = dev_get_priv(dev);
+
+	if (!sb_dsa_master_enabled(dev))
+		return -EFAULT;
+
+	priv->port_en_mask |= BIT(port);
+
+	return 0;
+}
+
+static void dsa_sandbox_port_disable(struct udevice *dev, int port,
+				     struct phy_device *phy)
+{
+	struct dsa_sandbox_priv *priv = dev_get_priv(dev);
+
+	priv->port_en_mask &= ~BIT(port);
+}
+
+static int dsa_sandbox_xmit(struct udevice *dev, int port, void *packet,
+			    int length)
+{
+	struct dsa_sandbox_tag *tag = packet;
+
+	if (!sb_dsa_master_enabled(dev))
+		return -EFAULT;
+
+	if (!sb_dsa_port_enabled(dev, port))
+		return -EFAULT;
+
+	tag->magic = DSA_SANDBOX_MAGIC;
+	tag->port = port;
+
+	return 0;
+}
+
+static int dsa_sandbox_rcv(struct udevice *dev, int *port, void *packet,
+			   int length)
+{
+	struct dsa_sandbox_tag *tag = packet;
+
+	if (!sb_dsa_master_enabled(dev))
+		return -EFAULT;
+
+	if (tag->magic != DSA_SANDBOX_MAGIC)
+		return -EFAULT;
+
+	*port = tag->port;
+	if (!sb_dsa_port_enabled(dev, tag->port))
+		return -EFAULT;
+
+	return 0;
+}
+
+static const struct dsa_ops dsa_sandbox_ops = {
+	.port_enable = dsa_sandbox_port_enable,
+	.port_disable = dsa_sandbox_port_disable,
+	.xmit = dsa_sandbox_xmit,
+	.rcv = dsa_sandbox_rcv,
+};
+
+static int sb_dsa_handler(struct udevice *dev, void *packet,
+			  unsigned int len)
+{
+	struct eth_sandbox_priv *master_priv;
+	struct dsa_sandbox_tag *tag = packet;
+	struct udevice *dsa_dev;
+	u32 port_index;
+	void *rx_buf;
+	int i;
+
+	/* this emulates the switch hw and the network side */
+	if (tag->magic != DSA_SANDBOX_MAGIC)
+		return -EFAULT;
+
+	port_index = tag->port;
+	master_priv = dev_get_priv(dev);
+	dsa_dev = master_priv->priv;
+	if (!sb_dsa_port_enabled(dsa_dev, port_index))
+		return -EFAULT;
+
+	packet += DSA_SANDBOX_TAG_LEN;
+	len -= DSA_SANDBOX_TAG_LEN;
+
+	if (!sandbox_eth_arp_req_to_reply(dev, packet, len))
+		goto dsa_tagging;
+	if (!sandbox_eth_ping_req_to_reply(dev, packet, len))
+		goto dsa_tagging;
+
+	return 0;
+
+dsa_tagging:
+	master_priv->recv_packets--;
+	i = master_priv->recv_packets;
+	rx_buf = master_priv->recv_packet_buffer[i];
+	len = master_priv->recv_packet_length[i];
+	memmove(rx_buf + DSA_SANDBOX_TAG_LEN, rx_buf, len);
+
+	tag = rx_buf;
+	tag->magic = DSA_SANDBOX_MAGIC;
+	tag->port = port_index;
+	len += DSA_SANDBOX_TAG_LEN;
+	master_priv->recv_packet_length[i] = len;
+	master_priv->recv_packets++;
+
+	return 0;
+}
+
+static int dsa_sandbox_probe(struct udevice *dev)
+{
+	struct dsa_sandbox_priv *priv = dev_get_priv(dev);
+	struct udevice *master = dsa_get_master(dev);
+	struct eth_sandbox_priv *master_priv;
+
+	if (!master)
+		return -ENODEV;
+
+	dsa_set_tagging(dev, DSA_SANDBOX_TAG_LEN, 0);
+
+	master_priv = dev_get_priv(master);
+	master_priv->priv = dev;
+	master_priv->tx_handler = sb_dsa_handler;
+
+	priv->master_priv = master_priv;
+
+	return 0;
+}
+
+static const struct udevice_id dsa_sandbox_ids[] = {
+	{ .compatible = "sandbox,dsa" },
+	{ }
+};
+
+U_BOOT_DRIVER(dsa_sandbox) = {
+	.name		= "dsa_sandbox",
+	.id		= UCLASS_DSA,
+	.of_match	= dsa_sandbox_ids,
+	.probe		= dsa_sandbox_probe,
+	.ops		= &dsa_sandbox_ops,
+	.priv_auto	= sizeof(struct dsa_sandbox_priv),
+};