net: dsa: move tagging protocol code to tag.{c,h}

It would be nice if tagging protocol drivers could include just the
header they need, since they are (mostly) data path and isolated from
most of the other DSA core code does.

Create a tag.c and a tag.h file which are meant to support tagging
protocol drivers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 243 insertions, 0 deletions

diff --git a/net/dsa/tag.c b/net/dsa/tag.c
new file mode 100644
index 000000000000..383721e167d6
--- /dev/null
+++ b/net/dsa/tag.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DSA tagging protocol handling
+ *
+ * Copyright (c) 2008-2009 Marvell Semiconductor
+ * Copyright (c) 2013 Florian Fainelli <florian@openwrt.org>
+ * Copyright (c) 2016 Andrew Lunn <andrew@lunn.ch>
+ */
+
+#include <linux/netdevice.h>
+#include <linux/ptp_classify.h>
+#include <linux/skbuff.h>
+#include <net/dsa.h>
+#include <net/dst_metadata.h>
+
+#include "slave.h"
+#include "tag.h"
+
+static LIST_HEAD(dsa_tag_drivers_list);
+static DEFINE_MUTEX(dsa_tag_drivers_lock);
+
+/* Determine if we should defer delivery of skb until we have a rx timestamp.
+ *
+ * Called from dsa_switch_rcv. For now, this will only work if tagging is
+ * enabled on the switch. Normally the MAC driver would retrieve the hardware
+ * timestamp when it reads the packet out of the hardware. However in a DSA
+ * switch, the DSA driver owning the interface to which the packet is
+ * delivered is never notified unless we do so here.
+ */
+static bool dsa_skb_defer_rx_timestamp(struct dsa_slave_priv *p,
+				       struct sk_buff *skb)
+{
+	struct dsa_switch *ds = p->dp->ds;
+	unsigned int type;
+
+	if (skb_headroom(skb) < ETH_HLEN)
+		return false;
+
+	__skb_push(skb, ETH_HLEN);
+
+	type = ptp_classify_raw(skb);
+
+	__skb_pull(skb, ETH_HLEN);
+
+	if (type == PTP_CLASS_NONE)
+		return false;
+
+	if (likely(ds->ops->port_rxtstamp))
+		return ds->ops->port_rxtstamp(ds, p->dp->index, skb, type);
+
+	return false;
+}
+
+static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
+			  struct packet_type *pt, struct net_device *unused)
+{
+	struct metadata_dst *md_dst = skb_metadata_dst(skb);
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	struct sk_buff *nskb = NULL;
+	struct dsa_slave_priv *p;
+
+	if (unlikely(!cpu_dp)) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	skb = skb_unshare(skb, GFP_ATOMIC);
+	if (!skb)
+		return 0;
+
+	if (md_dst && md_dst->type == METADATA_HW_PORT_MUX) {
+		unsigned int port = md_dst->u.port_info.port_id;
+
+		skb_dst_drop(skb);
+		if (!skb_has_extensions(skb))
+			skb->slow_gro = 0;
+
+		skb->dev = dsa_master_find_slave(dev, 0, port);
+		if (likely(skb->dev)) {
+			dsa_default_offload_fwd_mark(skb);
+			nskb = skb;
+		}
+	} else {
+		nskb = cpu_dp->rcv(skb, dev);
+	}
+
+	if (!nskb) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	skb = nskb;
+	skb_push(skb, ETH_HLEN);
+	skb->pkt_type = PACKET_HOST;
+	skb->protocol = eth_type_trans(skb, skb->dev);
+
+	if (unlikely(!dsa_slave_dev_check(skb->dev))) {
+		/* Packet is to be injected directly on an upper
+		 * device, e.g. a team/bond, so skip all DSA-port
+		 * specific actions.
+		 */
+		netif_rx(skb);
+		return 0;
+	}
+
+	p = netdev_priv(skb->dev);
+
+	if (unlikely(cpu_dp->ds->untag_bridge_pvid)) {
+		nskb = dsa_untag_bridge_pvid(skb);
+		if (!nskb) {
+			kfree_skb(skb);
+			return 0;
+		}
+		skb = nskb;
+	}
+
+	dev_sw_netstats_rx_add(skb->dev, skb->len);
+
+	if (dsa_skb_defer_rx_timestamp(p, skb))
+		return 0;
+
+	gro_cells_receive(&p->gcells, skb);
+
+	return 0;
+}
+
+struct packet_type dsa_pack_type __read_mostly = {
+	.type	= cpu_to_be16(ETH_P_XDSA),
+	.func	= dsa_switch_rcv,
+};
+
+static void dsa_tag_driver_register(struct dsa_tag_driver *dsa_tag_driver,
+				    struct module *owner)
+{
+	dsa_tag_driver->owner = owner;
+
+	mutex_lock(&dsa_tag_drivers_lock);
+	list_add_tail(&dsa_tag_driver->list, &dsa_tag_drivers_list);
+	mutex_unlock(&dsa_tag_drivers_lock);
+}
+
+void dsa_tag_drivers_register(struct dsa_tag_driver *dsa_tag_driver_array[],
+			      unsigned int count, struct module *owner)
+{
+	unsigned int i;
+
+	for (i = 0; i < count; i++)
+		dsa_tag_driver_register(dsa_tag_driver_array[i], owner);
+}
+
+static void dsa_tag_driver_unregister(struct dsa_tag_driver *dsa_tag_driver)
+{
+	mutex_lock(&dsa_tag_drivers_lock);
+	list_del(&dsa_tag_driver->list);
+	mutex_unlock(&dsa_tag_drivers_lock);
+}
+EXPORT_SYMBOL_GPL(dsa_tag_drivers_register);
+
+void dsa_tag_drivers_unregister(struct dsa_tag_driver *dsa_tag_driver_array[],
+				unsigned int count)
+{
+	unsigned int i;
+
+	for (i = 0; i < count; i++)
+		dsa_tag_driver_unregister(dsa_tag_driver_array[i]);
+}
+EXPORT_SYMBOL_GPL(dsa_tag_drivers_unregister);
+
+const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops)
+{
+	return ops->name;
+};
+
+/* Function takes a reference on the module owning the tagger,
+ * so dsa_tag_driver_put must be called afterwards.
+ */
+const struct dsa_device_ops *dsa_tag_driver_get_by_name(const char *name)
+{
+	const struct dsa_device_ops *ops = ERR_PTR(-ENOPROTOOPT);
+	struct dsa_tag_driver *dsa_tag_driver;
+
+	request_module("%s%s", DSA_TAG_DRIVER_ALIAS, name);
+
+	mutex_lock(&dsa_tag_drivers_lock);
+	list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
+		const struct dsa_device_ops *tmp = dsa_tag_driver->ops;
+
+		if (strcmp(name, tmp->name))
+			continue;
+
+		if (!try_module_get(dsa_tag_driver->owner))
+			break;
+
+		ops = tmp;
+		break;
+	}
+	mutex_unlock(&dsa_tag_drivers_lock);
+
+	return ops;
+}
+
+const struct dsa_device_ops *dsa_tag_driver_get_by_id(int tag_protocol)
+{
+	struct dsa_tag_driver *dsa_tag_driver;
+	const struct dsa_device_ops *ops;
+	bool found = false;
+
+	request_module("%sid-%d", DSA_TAG_DRIVER_ALIAS, tag_protocol);
+
+	mutex_lock(&dsa_tag_drivers_lock);
+	list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
+		ops = dsa_tag_driver->ops;
+		if (ops->proto == tag_protocol) {
+			found = true;
+			break;
+		}
+	}
+
+	if (found) {
+		if (!try_module_get(dsa_tag_driver->owner))
+			ops = ERR_PTR(-ENOPROTOOPT);
+	} else {
+		ops = ERR_PTR(-ENOPROTOOPT);
+	}
+
+	mutex_unlock(&dsa_tag_drivers_lock);
+
+	return ops;
+}
+
+void dsa_tag_driver_put(const struct dsa_device_ops *ops)
+{
+	struct dsa_tag_driver *dsa_tag_driver;
+
+	mutex_lock(&dsa_tag_drivers_lock);
+	list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
+		if (dsa_tag_driver->ops == ops) {
+			module_put(dsa_tag_driver->owner);
+			break;
+		}
+	}
+	mutex_unlock(&dsa_tag_drivers_lock);
+}