net: dsa: microchip: move max mtu to one location

There are no HW specific registers, so we can process all of them
in one location.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Tested-by: Arun Ramadoss <arun.ramadoss@microchip.com> (KSZ9893 and LAN937x)
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/dsa/microchip/ksz9477.c

@@ -60,11 +60,6 @@ int ksz9477_change_mtu(struct ksz_device *dev, int port, int mtu)
 				  REG_SW_MTU_MASK, max_frame);
 }
 
-int ksz9477_max_mtu(struct ksz_device *dev, int port)
-{
-	return KSZ9477_MAX_FRAME_SIZE - VLAN_ETH_HLEN - ETH_FCS_LEN;
-}
-
 static int ksz9477_wait_vlan_ctrl_ready(struct ksz_device *dev)
 {
 	unsigned int val;

drivers/net/dsa/microchip/ksz9477.h

@@ -50,7 +50,6 @@ int ksz9477_mdb_add(struct ksz_device *dev, int port,
 int ksz9477_mdb_del(struct ksz_device *dev, int port,
 		    const struct switchdev_obj_port_mdb *mdb, struct dsa_db db);
 int ksz9477_change_mtu(struct ksz_device *dev, int port, int mtu);
-int ksz9477_max_mtu(struct ksz_device *dev, int port);
 void ksz9477_config_cpu_port(struct dsa_switch *ds);
 int ksz9477_enable_stp_addr(struct ksz_device *dev);
 int ksz9477_reset_switch(struct ksz_device *dev);

drivers/net/dsa/microchip/ksz9477_reg.h

@@ -1615,6 +1615,4 @@
 #define PTP_TRIG_UNIT_M			(BIT(MAX_TRIG_UNIT) - 1)
 #define PTP_TS_UNIT_M			(BIT(MAX_TIMESTAMP_UNIT) - 1)
 
-#define KSZ9477_MAX_FRAME_SIZE		9000
-
 #endif /* KSZ9477_REGS_H */

drivers/net/dsa/microchip/ksz_common.c

@@ -14,6 +14,7 @@
 #include <linux/phy.h>
 #include <linux/etherdevice.h>
 #include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/of_mdio.h>
@@ -206,7 +207,6 @@ static const struct ksz_dev_ops ksz9477_dev_ops = {
 	.mdb_add = ksz9477_mdb_add,
 	.mdb_del = ksz9477_mdb_del,
 	.change_mtu = ksz9477_change_mtu,
-	.max_mtu = ksz9477_max_mtu,
 	.phylink_mac_link_up = ksz9477_phylink_mac_link_up,
 	.config_cpu_port = ksz9477_config_cpu_port,
 	.enable_stp_addr = ksz9477_enable_stp_addr,
@@ -243,7 +243,6 @@ static const struct ksz_dev_ops lan937x_dev_ops = {
 	.mdb_add = ksz9477_mdb_add,
 	.mdb_del = ksz9477_mdb_del,
 	.change_mtu = lan937x_change_mtu,
-	.max_mtu = ksz9477_max_mtu,
 	.phylink_mac_link_up = ksz9477_phylink_mac_link_up,
 	.config_cpu_port = lan937x_config_cpu_port,
 	.enable_stp_addr = ksz9477_enable_stp_addr,
@@ -2500,10 +2499,23 @@ static int ksz_max_mtu(struct dsa_switch *ds, int port)
 {
 	struct ksz_device *dev = ds->priv;
 
-	if (!dev->dev_ops->max_mtu)
-		return -EOPNOTSUPP;
+	switch (dev->chip_id) {
+	case KSZ8563_CHIP_ID:
+	case KSZ9477_CHIP_ID:
+	case KSZ9563_CHIP_ID:
+	case KSZ9567_CHIP_ID:
+	case KSZ9893_CHIP_ID:
+	case KSZ9896_CHIP_ID:
+	case KSZ9897_CHIP_ID:
+	case LAN9370_CHIP_ID:
+	case LAN9371_CHIP_ID:
+	case LAN9372_CHIP_ID:
+	case LAN9373_CHIP_ID:
+	case LAN9374_CHIP_ID:
+		return KSZ9477_MAX_FRAME_SIZE - VLAN_ETH_HLEN - ETH_FCS_LEN;
+	}
 
-	return dev->dev_ops->max_mtu(dev, port);
+	return -EOPNOTSUPP;
 }
 
 static void ksz_set_xmii(struct ksz_device *dev, int port,

drivers/net/dsa/microchip/ksz_common.h

@@ -322,7 +322,6 @@ struct ksz_dev_ops {
 	void (*get_caps)(struct ksz_device *dev, int port,
 			 struct phylink_config *config);
 	int (*change_mtu)(struct ksz_device *dev, int port, int mtu);
-	int (*max_mtu)(struct ksz_device *dev, int port);
 	void (*freeze_mib)(struct ksz_device *dev, int port, bool freeze);
 	void (*port_init_cnt)(struct ksz_device *dev, int port);
 	void (*phylink_mac_config)(struct ksz_device *dev, int port,
@@ -588,6 +587,8 @@ static inline int is_lan937x(struct ksz_device *dev)
 
 #define PORT_SRC_PHY_INT		1
 
+#define KSZ9477_MAX_FRAME_SIZE		9000
+
 /* Regmap tables generation */
 #define KSZ_SPI_OP_RD		3
 #define KSZ_SPI_OP_WR		2