net: Introduce DSA class for Ethernet switches

DSA stands for Distributed Switch Architecture and it covers switches that
are connected to the CPU through an Ethernet link and generally use frame
tags to pass information about the source/destination ports to/from CPU.
Front panel ports are presented as regular ethernet devices in U-Boot and
they are expected to support the typical networking commands.
DSA switches may be cascaded, DSA class code does not currently support
this.

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>

2 files changed, 479 insertions, 0 deletions

diff --git a/net/Makefile b/net/Makefile
index 76527f704c..fb3eba840f 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_NET)      += arp.o
 obj-$(CONFIG_CMD_BOOTP) += bootp.o
 obj-$(CONFIG_CMD_CDP)  += cdp.o
 obj-$(CONFIG_CMD_DNS)  += dns.o
+obj-$(CONFIG_DM_DSA)   += dsa-uclass.o
 ifdef CONFIG_DM_ETH
 obj-$(CONFIG_NET)      += eth-uclass.o
 else
diff --git a/net/dsa-uclass.c b/net/dsa-uclass.c
new file mode 100644
index 0000000000..2ce9ddb90d
--- /dev/null
+++ b/net/dsa-uclass.c
@@ -0,0 +1,478 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019-2021 NXP
+ */
+
+#include <net/dsa.h>
+#include <dm/lists.h>
+#include <dm/device_compat.h>
+#include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
+#include <linux/bitmap.h>
+#include <miiphy.h>
+
+#define DSA_PORT_CHILD_DRV_NAME "dsa-port"
+
+/* per-device internal state structure */
+struct dsa_priv {
+	struct phy_device *cpu_port_fixed_phy;
+	struct udevice *master_dev;
+	int num_ports;
+	u32 cpu_port;
+	int headroom;
+	int tailroom;
+};
+
+/* external API */
+int dsa_set_tagging(struct udevice *dev, ushort headroom, ushort tailroom)
+{
+	struct dsa_priv *priv;
+
+	if (!dev || !dev_get_uclass_priv(dev))
+		return -ENODEV;
+
+	if (headroom + tailroom > DSA_MAX_OVR)
+		return -EINVAL;
+
+	priv = dev_get_uclass_priv(dev);
+
+	if (headroom > 0)
+		priv->headroom = headroom;
+	if (tailroom > 0)
+		priv->tailroom = tailroom;
+
+	return 0;
+}
+
+/* returns the DSA master Ethernet device */
+struct udevice *dsa_get_master(struct udevice *dev)
+{
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+
+	if (!priv)
+		return NULL;
+
+	return priv->master_dev;
+}
+
+/*
+ * Start the desired port, the CPU port and the master Eth interface.
+ * TODO: if cascaded we may need to _start ports in other switches too
+ */
+static int dsa_port_start(struct udevice *pdev)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+	struct udevice *master = dsa_get_master(dev);
+	struct dsa_ops *ops = dsa_get_ops(dev);
+	int err;
+
+	if (!priv)
+		return -ENODEV;
+
+	if (!master) {
+		dev_err(pdev, "DSA master Ethernet device not found!\n");
+		return -EINVAL;
+	}
+
+	if (ops->port_enable) {
+		struct dsa_port_pdata *port_pdata;
+
+		port_pdata = dev_get_parent_plat(pdev);
+		err = ops->port_enable(dev, port_pdata->index,
+				       port_pdata->phy);
+		if (err)
+			return err;
+
+		err = ops->port_enable(dev, priv->cpu_port,
+				       priv->cpu_port_fixed_phy);
+		if (err)
+			return err;
+	}
+
+	return eth_get_ops(master)->start(master);
+}
+
+/* Stop the desired port, the CPU port and the master Eth interface */
+static void dsa_port_stop(struct udevice *pdev)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+	struct udevice *master = dsa_get_master(dev);
+	struct dsa_ops *ops = dsa_get_ops(dev);
+
+	if (!priv)
+		return;
+
+	if (ops->port_disable) {
+		struct dsa_port_pdata *port_pdata;
+
+		port_pdata = dev_get_parent_plat(pdev);
+		ops->port_disable(dev, port_pdata->index, port_pdata->phy);
+		ops->port_disable(dev, priv->cpu_port, NULL);
+	}
+
+	/*
+	 * stop master only if it's active, don't probe it otherwise.
+	 * Under normal usage it would be active because we're using it, but
+	 * during tear-down it may have been removed ahead of us.
+	 */
+	if (master && device_active(master))
+		eth_get_ops(master)->stop(master);
+}
+
+/*
+ * Insert a DSA tag and call master Ethernet send on the resulting packet
+ * We copy the frame to a stack buffer where we have reserved headroom and
+ * tailroom space.  Headroom and tailroom are set to 0.
+ */
+static int dsa_port_send(struct udevice *pdev, void *packet, int length)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+	int head = priv->headroom, tail = priv->tailroom;
+	struct udevice *master = dsa_get_master(dev);
+	struct dsa_ops *ops = dsa_get_ops(dev);
+	uchar dsa_packet_tmp[PKTSIZE_ALIGN];
+	struct dsa_port_pdata *port_pdata;
+	int err;
+
+	if (!master)
+		return -EINVAL;
+
+	if (length + head + tail > PKTSIZE_ALIGN)
+		return -EINVAL;
+
+	memset(dsa_packet_tmp, 0, head);
+	memset(dsa_packet_tmp + head + length, 0, tail);
+	memcpy(dsa_packet_tmp + head, packet, length);
+	length += head + tail;
+	/* copy back to preserve original buffer alignment */
+	memcpy(packet, dsa_packet_tmp, length);
+
+	port_pdata = dev_get_parent_plat(pdev);
+	err = ops->xmit(dev, port_pdata->index, packet, length);
+	if (err)
+		return err;
+
+	return eth_get_ops(master)->send(master, packet, length);
+}
+
+/* Receive a frame from master Ethernet, process it and pass it on */
+static int dsa_port_recv(struct udevice *pdev, int flags, uchar **packetp)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+	int head = priv->headroom, tail = priv->tailroom;
+	struct udevice *master = dsa_get_master(dev);
+	struct dsa_ops *ops = dsa_get_ops(dev);
+	struct dsa_port_pdata *port_pdata;
+	int length, port_index, err;
+
+	if (!master)
+		return -EINVAL;
+
+	length = eth_get_ops(master)->recv(master, flags, packetp);
+	if (length <= 0)
+		return length;
+
+	/*
+	 * If we receive frames from a different port or frames that DSA driver
+	 * doesn't like we discard them here.
+	 * In case of discard we return with no frame and expect to be called
+	 * again instead of looping here, so upper layer can deal with timeouts.
+	 */
+	port_pdata = dev_get_parent_plat(pdev);
+	err = ops->rcv(dev, &port_index, *packetp, length);
+	if (err || port_index != port_pdata->index || (length <= head + tail)) {
+		if (eth_get_ops(master)->free_pkt)
+			eth_get_ops(master)->free_pkt(master, *packetp, length);
+		return -EAGAIN;
+	}
+
+	/*
+	 * We move the pointer over headroom here to avoid a copy.  If free_pkt
+	 * gets called we move the pointer back before calling master free_pkt.
+	 */
+	*packetp += head;
+
+	return length - head - tail;
+}
+
+static int dsa_port_free_pkt(struct udevice *pdev, uchar *packet, int length)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct udevice *master = dsa_get_master(dev);
+	struct dsa_priv *priv;
+
+	if (!master)
+		return -EINVAL;
+
+	priv = dev_get_uclass_priv(dev);
+	if (eth_get_ops(master)->free_pkt) {
+		/* return the original pointer and length to master Eth */
+		packet -= priv->headroom;
+		length += priv->headroom - priv->tailroom;
+
+		return eth_get_ops(master)->free_pkt(master, packet, length);
+	}
+
+	return 0;
+}
+
+static int dsa_port_of_to_pdata(struct udevice *pdev)
+{
+	struct dsa_port_pdata *port_pdata;
+	struct dsa_pdata *dsa_pdata;
+	struct eth_pdata *eth_pdata;
+	struct udevice *dev;
+	const char *label;
+	u32 index;
+	int err;
+
+	if (!pdev)
+		return -ENODEV;
+
+	err = ofnode_read_u32(dev_ofnode(pdev), "reg", &index);
+	if (err)
+		return err;
+
+	dev = dev_get_parent(pdev);
+	dsa_pdata = dev_get_uclass_plat(dev);
+
+	port_pdata = dev_get_parent_plat(pdev);
+	port_pdata->index = index;
+
+	label = ofnode_read_string(dev_ofnode(pdev), "label");
+	if (label)
+		strncpy(port_pdata->name, label, DSA_PORT_NAME_LENGTH);
+
+	eth_pdata = dev_get_plat(pdev);
+	eth_pdata->priv_pdata = port_pdata;
+
+	dev_dbg(pdev, "port %d node %s\n", port_pdata->index,
+		ofnode_get_name(dev_ofnode(pdev)));
+
+	return 0;
+}
+
+static const struct eth_ops dsa_port_ops = {
+	.start		= dsa_port_start,
+	.send		= dsa_port_send,
+	.recv		= dsa_port_recv,
+	.stop		= dsa_port_stop,
+	.free_pkt	= dsa_port_free_pkt,
+};
+
+static int dsa_port_probe(struct udevice *pdev)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct eth_pdata *eth_pdata, *master_pdata;
+	unsigned char env_enetaddr[ARP_HLEN];
+	struct dsa_port_pdata *port_pdata;
+	struct dsa_priv *dsa_priv;
+	struct udevice *master;
+
+	port_pdata = dev_get_parent_plat(pdev);
+	dsa_priv = dev_get_uclass_priv(dev);
+
+	port_pdata->phy = dm_eth_phy_connect(pdev);
+	if (!port_pdata->phy)
+		return -ENODEV;
+
+	/*
+	 * Inherit port's hwaddr from the DSA master, unless the port already
+	 * has a unique MAC address specified in the environment.
+	 */
+	eth_env_get_enetaddr_by_index("eth", dev_seq(pdev), env_enetaddr);
+	if (!is_zero_ethaddr(env_enetaddr))
+		return 0;
+
+	master = dsa_get_master(dev);
+	if (!master)
+		return 0;
+
+	master_pdata = dev_get_plat(master);
+	eth_pdata = dev_get_plat(pdev);
+	memcpy(eth_pdata->enetaddr, master_pdata->enetaddr, ARP_HLEN);
+	eth_env_set_enetaddr_by_index("eth", dev_seq(pdev),
+				      master_pdata->enetaddr);
+
+	return 0;
+}
+
+static int dsa_port_remove(struct udevice *pdev)
+{
+	struct udevice *dev = dev_get_parent(pdev);
+	struct dsa_port_pdata *port_pdata;
+	struct dsa_priv *dsa_priv;
+
+	port_pdata = dev_get_parent_plat(pdev);
+	dsa_priv = dev_get_uclass_priv(dev);
+
+	port_pdata->phy = NULL;
+
+	return 0;
+}
+
+U_BOOT_DRIVER(dsa_port) = {
+	.name	= DSA_PORT_CHILD_DRV_NAME,
+	.id	= UCLASS_ETH,
+	.ops	= &dsa_port_ops,
+	.probe	= dsa_port_probe,
+	.remove	= dsa_port_remove,
+	.of_to_plat = dsa_port_of_to_pdata,
+	.plat_auto = sizeof(struct eth_pdata),
+};
+
+/*
+ * This function mostly deals with pulling information out of the device tree
+ * into the pdata structure.
+ * It goes through the list of switch ports, registers an eth device for each
+ * front panel port and identifies the cpu port connected to master eth device.
+ * TODO: support cascaded switches
+ */
+static int dsa_post_bind(struct udevice *dev)
+{
+	struct dsa_pdata *pdata = dev_get_uclass_plat(dev);
+	ofnode node = dev_ofnode(dev), pnode;
+	int i, err, first_err = 0;
+
+	if (!pdata || !ofnode_valid(node))
+		return -ENODEV;
+
+	pdata->master_node = ofnode_null();
+
+	node = ofnode_find_subnode(node, "ports");
+	if (!ofnode_valid(node))
+		node = ofnode_find_subnode(node, "ethernet-ports");
+	if (!ofnode_valid(node)) {
+		dev_err(dev, "ports node is missing under DSA device!\n");
+		return -EINVAL;
+	}
+
+	pdata->num_ports = ofnode_get_child_count(node);
+	if (pdata->num_ports <= 0 || pdata->num_ports > DSA_MAX_PORTS) {
+		dev_err(dev, "invalid number of ports (%d)\n",
+			pdata->num_ports);
+		return -EINVAL;
+	}
+
+	/* look for the CPU port */
+	ofnode_for_each_subnode(pnode, node) {
+		u32 ethernet;
+
+		if (ofnode_read_u32(pnode, "ethernet", &ethernet))
+			continue;
+
+		pdata->master_node = ofnode_get_by_phandle(ethernet);
+		pdata->cpu_port_node = pnode;
+		break;
+	}
+
+	if (!ofnode_valid(pdata->master_node)) {
+		dev_err(dev, "master eth node missing!\n");
+		return -EINVAL;
+	}
+
+	if (ofnode_read_u32(pnode, "reg", &pdata->cpu_port)) {
+		dev_err(dev, "CPU port node not valid!\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(dev, "master node %s on port %d\n",
+		ofnode_get_name(pdata->master_node), pdata->cpu_port);
+
+	for (i = 0; i < pdata->num_ports; i++) {
+		char name[DSA_PORT_NAME_LENGTH];
+		struct udevice *pdev;
+
+		/*
+		 * If this is the CPU port don't register it as an ETH device,
+		 * we skip it on purpose since I/O to/from it from the CPU
+		 * isn't useful.
+		 */
+		if (i == pdata->cpu_port)
+			continue;
+
+		/*
+		 * Set up default port names.  If present, DT port labels
+		 * will override the default port names.
+		 */
+		snprintf(name, DSA_PORT_NAME_LENGTH, "%s@%d", dev->name, i);
+
+		ofnode_for_each_subnode(pnode, node) {
+			u32 reg;
+
+			if (ofnode_read_u32(pnode, "reg", &reg))
+				continue;
+
+			if (reg == i)
+				break;
+		}
+
+		/*
+		 * skip registration if port id not found or if the port
+		 * is explicitly disabled in DT
+		 */
+		if (!ofnode_valid(pnode) || !ofnode_is_available(pnode))
+			continue;
+
+		err = device_bind_driver_to_node(dev, DSA_PORT_CHILD_DRV_NAME,
+						 name, pnode, &pdev);
+		if (pdev) {
+			struct dsa_port_pdata *port_pdata;
+
+			port_pdata = dev_get_parent_plat(pdev);
+			strncpy(port_pdata->name, name, DSA_PORT_NAME_LENGTH);
+			pdev->name = port_pdata->name;
+		}
+
+		/* try to bind all ports but keep 1st error */
+		if (err && !first_err)
+			first_err = err;
+	}
+
+	if (first_err)
+		return first_err;
+
+	dev_dbg(dev, "DSA ports successfully bound\n");
+
+	return 0;
+}
+
+/**
+ * Initialize the uclass per device internal state structure (priv).
+ * TODO: pick up references to other switch devices here, if we're cascaded.
+ */
+static int dsa_pre_probe(struct udevice *dev)
+{
+	struct dsa_pdata *pdata = dev_get_uclass_plat(dev);
+	struct dsa_priv *priv = dev_get_uclass_priv(dev);
+
+	if (!pdata || !priv)
+		return -ENODEV;
+
+	priv->num_ports = pdata->num_ports;
+	priv->cpu_port = pdata->cpu_port;
+	priv->cpu_port_fixed_phy = fixed_phy_create(pdata->cpu_port_node);
+	if (!priv->cpu_port_fixed_phy) {
+		dev_err(dev, "Failed to register fixed-link for CPU port\n");
+		return -ENODEV;
+	}
+
+	uclass_find_device_by_ofnode(UCLASS_ETH, pdata->master_node,
+				     &priv->master_dev);
+	return 0;
+}
+
+UCLASS_DRIVER(dsa) = {
+	.id = UCLASS_DSA,
+	.name = "dsa",
+	.post_bind = dsa_post_bind,
+	.pre_probe = dsa_pre_probe,
+	.per_device_auto = sizeof(struct dsa_priv),
+	.per_device_plat_auto = sizeof(struct dsa_pdata),
+	.per_child_plat_auto = sizeof(struct dsa_port_pdata),
+	.flags = DM_UC_FLAG_SEQ_ALIAS,
+};