realtek: l3: give the DMAC entries a callback of their own

The DMAC entries are written through set_egress_mac() and keyed on the
gateway's MAC alone. That is what an RTL930x L3_EGR_INTF_MAC entry
holds, but an RTL839x ROUTING row also names the switch MAC entry a
routed frame leaves with (SW_MAC_IDX), and routing with the MAC of the
device a route goes out of needs a row per gateway MAC and switch MAC
entry.

Give the entries a callback of their own, set_dmac(), which takes what
an entry holds, struct otto_l3_dmac: the gateway's MAC and the switch
MAC entry, which RTL930x does not take. RTL930x writes the entry
through otto_l3_930x_set_egress_mac() as before. RTL839x writes the
ROUTING row with SW_MAC_IDX from it, so set_egress_mac() is RTL930x's
alone now.

No functional change: every entry still holds a switch MAC entry of 0,
so the rows and the DMAC entries written, and which routes share them,
are as they were. Compile-tested on rtl839x and rtl930x; route-tested
on an HPE 1920-48G (RTL8393) together with the following patch, on
f29dfe25ba.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Gennaro Cimmino <gcimmino@rayonra.net>
Link: https://github.com/openwrt/openwrt/pull/25822
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>

target/linux/realtek/files-6.18/drivers/net/dsa/rtl83xx/l3.c

@@ -187,13 +187,14 @@ static void otto_l3_839x_nexthop_read(struct otto_l3_ctrl *ctrl, int idx, struct
 }
 
 /* A ROUTING row holds a gateway's MAC and the index of the source MAC to
- * route with, left at 0. The routes through one gateway share its row, the
+ * route with (SW_MAC_IDX). The routes through one gateway share its row, the
  * way RTL930x routes share a DMAC entry: the L2 entry of the gateway names
  * one row, whichever route claimed it.
  */
-static int otto_l3_839x_set_egress_mac(struct otto_l3_ctrl *ctrl, u32 idx, u64 mac)
+static int otto_l3_839x_set_dmac(struct otto_l3_ctrl *ctrl, u32 idx,
+				 const struct otto_l3_dmac *dmac)
 {
-	u32 data[2] = { mac >> 16, mac << 16 };
+	u32 data[2] = { dmac->mac >> 16, dmac->mac << 16 | (dmac->smac_id & 0xf) << 12 };
 
 	return otto_table_write(RTL8390_TBL_ROUTING, idx, &data);
 }
@@ -360,6 +361,12 @@ static int otto_l3_930x_set_egress_mac(struct otto_l3_ctrl *ctrl, u32 idx, u64 m
 	return otto_table_write(RTL9300_TBL_L3_EGR_INTF_MAC, idx, &data);
 }
 
+static int otto_l3_930x_set_dmac(struct otto_l3_ctrl *ctrl, u32 idx,
+				 const struct otto_l3_dmac *dmac)
+{
+	return otto_l3_930x_set_egress_mac(ctrl, idx, dmac->mac);
+}
+
 /* Decode a host route entry fetched into @data. Returns false unless it is a
  * valid unicast entry; valid is set for any entry, type for any valid one.
  */
@@ -1674,6 +1681,11 @@ static void otto_l3_route_rewrite(struct otto_l3_ctrl *ctrl, struct otto_l3_rout
 	}
 }
 
+static bool otto_l3_dmac_equal(const struct otto_l3_dmac *a, const struct otto_l3_dmac *b)
+{
+	return a->mac == b->mac && a->smac_id == b->smac_id;
+}
+
 /* Routes through one gateway share its L2 entry, and that names a single
  * DMAC entry, whichever route claimed it first. So the entry is held per MAC
  * by every route through it, the way the SDK holds it
@@ -1682,14 +1694,14 @@ static void otto_l3_route_rewrite(struct otto_l3_ctrl *ctrl, struct otto_l3_rout
  * than entries. Entry 0 stays unused, as it did while route 0, which is never
  * allocated, named it.
  */
-static int otto_l3_dmac_get(struct otto_l3_ctrl *ctrl, u64 mac)
+static int otto_l3_dmac_get(struct otto_l3_ctrl *ctrl, const struct otto_l3_dmac *dmac)
 {
 	int i, unused = -1, err;
 
 	mutex_lock(ctrl->lock);
 
 	for (i = 1; i < MAX_DMACS; i++) {
-		if (ctrl->dmac_refs[i] && ctrl->dmacs[i] == mac)
+		if (ctrl->dmac_refs[i] && otto_l3_dmac_equal(&ctrl->dmacs[i], dmac))
 			break;
 		if (unused < 0 && !ctrl->dmac_refs[i])
 			unused = i;
@@ -1703,12 +1715,12 @@ static int otto_l3_dmac_get(struct otto_l3_ctrl *ctrl, u64 mac)
 		}
 
 		/* An entry whose write failed stays free */
-		err = ctrl->cfg->set_egress_mac(ctrl, i, mac);
+		err = ctrl->cfg->set_dmac(ctrl, i, dmac);
 		if (err) {
 			i = err;
 			goto out;
 		}
-		ctrl->dmacs[i] = mac;
+		ctrl->dmacs[i] = *dmac;
 	}
 
 	ctrl->dmac_refs[i]++;
@@ -1720,7 +1732,7 @@ out:
 
 static void otto_l3_dmac_put(struct otto_l3_ctrl *ctrl, int idx)
 {
-	if (!ctrl->cfg->set_egress_mac || idx < 0)
+	if (!ctrl->cfg->set_dmac || idx < 0)
 		return;
 
 	mutex_lock(ctrl->lock);
@@ -1735,6 +1747,7 @@ static void otto_l3_route_update_hw(struct otto_l3_ctrl *ctrl, struct otto_l3_ro
 	char dst[INET6_ADDRSTRLEN + sizeof("/128")];
 	bool trapped = r->attr.action == ROUTE_ACT_TRAP2CPU;
 	int old_dmac = r->nh.dmac_id;
+	struct otto_l3_dmac key = { .mac = mac };
 	bool first = !r->nh.mac;
 	bool no_port, no_l2, trap;
 	int dmac = r->id;
@@ -1759,8 +1772,8 @@ static void otto_l3_route_update_hw(struct otto_l3_ctrl *ctrl, struct otto_l3_ro
 		otto_l3_route_rewrite(ctrl, r);
 	}
 
-	if (ctrl->cfg->set_egress_mac) {
-		dmac = otto_l3_dmac_get(ctrl, mac);
+	if (ctrl->cfg->set_dmac) {
+		dmac = otto_l3_dmac_get(ctrl, &key);
 		if (dmac < 0) {
 			dev_err(ctrl->dev, "no DMAC entry for %016llx: %d\n", mac, dmac);
 			return;
@@ -4155,7 +4168,7 @@ const struct otto_l3_config otto_l3_838x_cfg = {
 };
 
 const struct otto_l3_config otto_l3_839x_cfg = {
-	.set_egress_mac = otto_l3_839x_set_egress_mac,
+	.set_dmac = otto_l3_839x_set_dmac,
 	.route_rows_move = otto_l3_839x_route_rows_move,
 	.route_write = otto_l3_839x_route_write,
 	.setup = otto_l3_839x_setup,
@@ -4168,6 +4181,7 @@ const struct otto_l3_config otto_l3_930x_cfg = {
 	.get_egress_intf = otto_l3_930x_get_egress_intf,
 	.get_egress_mac = otto_l3_930x_get_egress_mac,
 	.set_egress_mac = otto_l3_930x_set_egress_mac,
+	.set_dmac = otto_l3_930x_set_dmac,
 	.set_egress_intf = otto_l3_930x_set_egress_intf,
 	.host_route_write = otto_l3_930x_host_route_write,
 	.get_router_mac = otto_l3_930x_get_router_mac,
@@ -4330,7 +4344,7 @@ int otto_l3_probe(struct device *dev, struct rtl838x_switch_priv *priv)
 		return dev_err_probe(dev, -EINVAL, "No compatible configuration found\n");
 	ctrl->cfg = match->data;
 
-	if (ctrl->cfg->set_egress_mac) {
+	if (ctrl->cfg->set_dmac) {
 		ctrl->dmacs = devm_kcalloc(dev, MAX_DMACS, sizeof(*ctrl->dmacs), GFP_KERNEL);
 		ctrl->dmac_refs = devm_kcalloc(dev, MAX_DMACS, sizeof(*ctrl->dmac_refs),
 					       GFP_KERNEL);

target/linux/realtek/files-6.18/drivers/net/dsa/rtl83xx/l3.h

@@ -103,6 +103,14 @@ struct otto_l3_route {
 	struct otto_l3_route_attr attr;
 };
 
+/* What a DMAC entry holds: a gateway's MAC and, on RTL839x, the switch MAC
+ * entry the frames routed to it leave with
+ */
+struct otto_l3_dmac {
+	u64 mac;
+	u16 smac_id;	/* not taken for RTL930x */
+};
+
 struct otto_l3_config {
 	/* Which of the two routing models the family uses. RTL930x writes the
 	 * destination and its mask into the route entry, so the L3 tables match
@@ -115,6 +123,7 @@ struct otto_l3_config {
 	void (*set_egress_intf)(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_intf *intf);
 	u64 (*get_egress_mac)(struct otto_l3_ctrl *ctrl, u32 idx);
 	int (*set_egress_mac)(struct otto_l3_ctrl *ctrl, u32 idx, u64 mac);
+	int (*set_dmac)(struct otto_l3_ctrl *ctrl, u32 idx, const struct otto_l3_dmac *dmac);
 	void (*host_route_write)(struct otto_l3_ctrl *ctrl, int idx, struct otto_l3_route *rt);
 	void (*get_router_mac)(struct otto_l3_ctrl *ctrl, u32 idx, struct otto_l3_router_mac *m);
 	void (*set_router_mac)(struct otto_l3_ctrl *ctrl, u32 idx, struct otto_l3_router_mac *m);
@@ -144,7 +153,7 @@ struct otto_l3_ctrl {
 	unsigned long host_route_use_bm[MAX_HOST_ROUTES / 32];
 	struct otto_l3_intf interfaces[MAX_SMACS];
 	unsigned int intf_refs[MAX_SMACS];	/* routes holding each */
-	u64 *dmacs;				/* gateway MAC of each DMAC entry */
+	struct otto_l3_dmac *dmacs;		/* what each DMAC entry holds */
 	unsigned int *dmac_refs;		/* routes holding each */
 	DECLARE_BITMAP(router_mac_bm, MAX_ROUTER_MACS);	/* entries written here */
 	bool prefix_rows_stale;	/* a move failed, the rows are not where we say */