net: dsa: mv88e6xxx: Disentangle STU from VTU

In early LinkStreet silicon (e.g. 6095/6185), the per-VLAN STP states
were kept in the VTU - there was no concept of a SID. Later, the
information was split into two tables, where the VTU only tracked
memberships and deferred the STP state tracking to the STU via a
pointer (SID). This meant that a group of VLANs could share the same
STU entry. Most likely, this was done to align with MSTP (802.1Q-2018,
Clause 13), which is built on this principle.

While the VTU is still 4k lines on most devices, the STU is capped at
64 entries. This means that the current stategy, updating STU info
whenever a VTU entry is updated, can not easily support MSTP because:

- The maximum number of VIDs would also be capped at 64, as we would
  have to allocate one SID for every VTU entry - even if many VLANs
  would effectively share the same MST.

- MSTP updates would be unnecessarily slow as you would have to
  iterate over all VLANs that share the same MST.

In order to support MSTP offloading in the future, manage the STU as a
separate entity from the VTU.

Only add support for newer hardware with separate VTU and
STU. VTU-only devices can also be supported, but essentially this
requires a software implementation of an STU (fanning out state
changed to all VLANs tied to the same MST).
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -1791,6 +1791,33 @@ static int mv88e6xxx_atu_new(struct mv88e6xxx_chip *chip, u16 *fid)
 	return mv88e6xxx_g1_atu_flush(chip, *fid, true);
 }
 
+static int mv88e6xxx_stu_loadpurge(struct mv88e6xxx_chip *chip,
+				   struct mv88e6xxx_stu_entry *entry)
+{
+	if (!chip->info->ops->stu_loadpurge)
+		return -EOPNOTSUPP;
+
+	return chip->info->ops->stu_loadpurge(chip, entry);
+}
+
+static int mv88e6xxx_stu_setup(struct mv88e6xxx_chip *chip)
+{
+	struct mv88e6xxx_stu_entry stu = {
+		.valid = true,
+		.sid = 0
+	};
+
+	if (!mv88e6xxx_has_stu(chip))
+		return 0;
+
+	/* Make sure that SID 0 is always valid. This is used by VTU
+	 * entries that do not make use of the STU, e.g. when creating
+	 * a VLAN upper on a port that is also part of a VLAN
+	 * filtering bridge.
+	 */
+	return mv88e6xxx_stu_loadpurge(chip, &stu);
+}
+
 static int mv88e6xxx_port_check_hw_vlan(struct dsa_switch *ds, int port,
 					u16 vid)
 {
@@ -3427,6 +3454,13 @@ static int mv88e6xxx_setup(struct dsa_switch *ds)
 	if (err)
 		goto unlock;
 
+	/* Must be called after mv88e6xxx_vtu_setup (which flushes the
+	 * VTU, thereby also flushing the STU).
+	 */
+	err = mv88e6xxx_stu_setup(chip);
+	if (err)
+		goto unlock;
+
 	/* Setup Switch Port Registers */
 	for (i = 0; i < mv88e6xxx_num_ports(chip); i++) {
 		if (dsa_is_unused_port(ds, i))
@@ -3882,6 +3916,8 @@ static const struct mv88e6xxx_ops mv88e6097_ops = {
 	.vtu_getnext = mv88e6352_g1_vtu_getnext,
 	.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
 	.phylink_get_caps = mv88e6095_phylink_get_caps,
+	.stu_getnext = mv88e6352_g1_stu_getnext,
+	.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
 	.set_max_frame_size = mv88e6185_g1_set_max_frame_size,
 };
 
@@ -4968,6 +5004,8 @@ static const struct mv88e6xxx_ops mv88e6352_ops = {
 	.atu_set_hash = mv88e6165_g1_atu_set_hash,
 	.vtu_getnext = mv88e6352_g1_vtu_getnext,
 	.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
+	.stu_getnext = mv88e6352_g1_stu_getnext,
+	.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
 	.serdes_get_lane = mv88e6352_serdes_get_lane,
 	.serdes_pcs_get_state = mv88e6352_serdes_pcs_get_state,
 	.serdes_pcs_config = mv88e6352_serdes_pcs_config,
@@ -5033,6 +5071,8 @@ static const struct mv88e6xxx_ops mv88e6390_ops = {
 	.atu_set_hash = mv88e6165_g1_atu_set_hash,
 	.vtu_getnext = mv88e6390_g1_vtu_getnext,
 	.vtu_loadpurge = mv88e6390_g1_vtu_loadpurge,
+	.stu_getnext = mv88e6390_g1_stu_getnext,
+	.stu_loadpurge = mv88e6390_g1_stu_loadpurge,
 	.serdes_power = mv88e6390_serdes_power,
 	.serdes_get_lane = mv88e6390_serdes_get_lane,
 	/* Check status register pause & lpa register */
@@ -5098,6 +5138,8 @@ static const struct mv88e6xxx_ops mv88e6390x_ops = {
 	.atu_set_hash = mv88e6165_g1_atu_set_hash,
 	.vtu_getnext = mv88e6390_g1_vtu_getnext,
 	.vtu_loadpurge = mv88e6390_g1_vtu_loadpurge,
+	.stu_getnext = mv88e6390_g1_stu_getnext,
+	.stu_loadpurge = mv88e6390_g1_stu_loadpurge,
 	.serdes_power = mv88e6390_serdes_power,
 	.serdes_get_lane = mv88e6390x_serdes_get_lane,
 	.serdes_pcs_get_state = mv88e6390_serdes_pcs_get_state,
@@ -5166,6 +5208,8 @@ static const struct mv88e6xxx_ops mv88e6393x_ops = {
 	.atu_set_hash = mv88e6165_g1_atu_set_hash,
 	.vtu_getnext = mv88e6390_g1_vtu_getnext,
 	.vtu_loadpurge = mv88e6390_g1_vtu_loadpurge,
+	.stu_getnext = mv88e6390_g1_stu_getnext,
+	.stu_loadpurge = mv88e6390_g1_stu_loadpurge,
 	.serdes_power = mv88e6393x_serdes_power,
 	.serdes_get_lane = mv88e6393x_serdes_get_lane,
 	.serdes_pcs_get_state = mv88e6393x_serdes_pcs_get_state,
@@ -5234,6 +5278,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_ports = 11,
 		.num_internal_phys = 8,
 		.max_vid = 4095,
+		.max_sid = 63,
 		.port_base_addr = 0x10,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5487,6 +5532,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_internal_phys = 9,
 		.num_gpio = 16,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5510,6 +5556,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_internal_phys = 9,
 		.num_gpio = 16,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5532,6 +5579,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_ports = 11,	/* 10 + Z80 */
 		.num_internal_phys = 9,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5554,6 +5602,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_ports = 11,	/* 10 + Z80 */
 		.num_internal_phys = 9,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5576,6 +5625,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_ports = 11,	/* 10 + Z80 */
 		.num_internal_phys = 9,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5815,6 +5865,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_internal_phys = 5,
 		.num_gpio = 15,
 		.max_vid = 4095,
+		.max_sid = 63,
 		.port_base_addr = 0x10,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5839,6 +5890,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_internal_phys = 9,
 		.num_gpio = 16,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5863,6 +5915,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_internal_phys = 9,
 		.num_gpio = 16,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,
@@ -5886,6 +5939,7 @@ static const struct mv88e6xxx_info mv88e6xxx_table[] = {
 		.num_ports = 11,	/* 10 + Z80 */
 		.num_internal_phys = 9,
 		.max_vid = 8191,
+		.max_sid = 63,
 		.port_base_addr = 0x0,
 		.phy_base_addr = 0x0,
 		.global1_addr = 0x1b,

drivers/net/dsa/mv88e6xxx/chip.h

@@ -20,6 +20,7 @@
 
 #define EDSA_HLEN		8
 #define MV88E6XXX_N_FID		4096
+#define MV88E6XXX_N_SID		64
 
 #define MV88E6XXX_FID_STANDALONE	0
 #define MV88E6XXX_FID_BRIDGED		1
@@ -130,6 +131,7 @@ struct mv88e6xxx_info {
 	unsigned int num_internal_phys;
 	unsigned int num_gpio;
 	unsigned int max_vid;
+	unsigned int max_sid;
 	unsigned int port_base_addr;
 	unsigned int phy_base_addr;
 	unsigned int global1_addr;
@@ -181,6 +183,12 @@ struct mv88e6xxx_vtu_entry {
 	bool	valid;
 	bool	policy;
 	u8	member[DSA_MAX_PORTS];
+	u8	state[DSA_MAX_PORTS];	/* Older silicon has no STU */
+};
+
+struct mv88e6xxx_stu_entry {
+	u8	sid;
+	bool	valid;
 	u8	state[DSA_MAX_PORTS];
 };
 
@@ -602,6 +610,12 @@ struct mv88e6xxx_ops {
 	int (*vtu_loadpurge)(struct mv88e6xxx_chip *chip,
 			     struct mv88e6xxx_vtu_entry *entry);
 
+	/* Spanning Tree Unit operations */
+	int (*stu_getnext)(struct mv88e6xxx_chip *chip,
+			   struct mv88e6xxx_stu_entry *entry);
+	int (*stu_loadpurge)(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_stu_entry *entry);
+
 	/* GPIO operations */
 	const struct mv88e6xxx_gpio_ops *gpio_ops;
 
@@ -700,6 +714,11 @@ struct mv88e6xxx_hw_stat {
 	int type;
 };
 
+static inline bool mv88e6xxx_has_stu(struct mv88e6xxx_chip *chip)
+{
+	return chip->info->max_sid > 0;
+}
+
 static inline bool mv88e6xxx_has_pvt(struct mv88e6xxx_chip *chip)
 {
 	return chip->info->pvt;
@@ -730,6 +749,11 @@ static inline unsigned int mv88e6xxx_max_vid(struct mv88e6xxx_chip *chip)
 	return chip->info->max_vid;
 }
 
+static inline unsigned int mv88e6xxx_max_sid(struct mv88e6xxx_chip *chip)
+{
+	return chip->info->max_sid;
+}
+
 static inline u16 mv88e6xxx_port_mask(struct mv88e6xxx_chip *chip)
 {
 	return GENMASK((s32)mv88e6xxx_num_ports(chip) - 1, 0);

drivers/net/dsa/mv88e6xxx/global1.h

@@ -348,6 +348,16 @@ int mv88e6390_g1_vtu_getnext(struct mv88e6xxx_chip *chip,
 int mv88e6390_g1_vtu_loadpurge(struct mv88e6xxx_chip *chip,
 			       struct mv88e6xxx_vtu_entry *entry);
 int mv88e6xxx_g1_vtu_flush(struct mv88e6xxx_chip *chip);
+int mv88e6xxx_g1_stu_getnext(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_stu_entry *entry);
+int mv88e6352_g1_stu_getnext(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_stu_entry *entry);
+int mv88e6352_g1_stu_loadpurge(struct mv88e6xxx_chip *chip,
+			       struct mv88e6xxx_stu_entry *entry);
+int mv88e6390_g1_stu_getnext(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_stu_entry *entry);
+int mv88e6390_g1_stu_loadpurge(struct mv88e6xxx_chip *chip,
+			       struct mv88e6xxx_stu_entry *entry);
 int mv88e6xxx_g1_vtu_prob_irq_setup(struct mv88e6xxx_chip *chip);
 void mv88e6xxx_g1_vtu_prob_irq_free(struct mv88e6xxx_chip *chip);
 int mv88e6xxx_g1_atu_get_next(struct mv88e6xxx_chip *chip, u16 fid);