net: dsa: microchip: ksz9477: implement MTU configuration

This chips supports two ways to configure max MTU size:
- by setting SW_LEGAL_PACKET_DISABLE bit: if this bit is 0 allowed packed size
  will be between 64 and bytes 1518. If this bit is 1, it will accept
  packets up to 2000 bytes.
- by setting SW_JUMBO_PACKET bit. If this bit is set, the chip will
  ignore SW_LEGAL_PACKET_DISABLE value and use REG_SW_MTU__2 register to
  configure MTU size.

Current driver has disabled SW_JUMBO_PACKET bit and activates
SW_LEGAL_PACKET_DISABLE. So the switch will pass all packets up to 2000 without
any way to configure it.

By providing port_change_mtu we are switch to SW_JUMBO_PACKET way and will
be able to configure MTU up to ~9000.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220308135857.1119028-1-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index 94ad6d9504f48ee1aa4e6d404e0b72b33089b92a..a4699481c746549819dc9de532642bf472f94900 100644 (file)
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -11,6 +11,7 @@
 #include <linux/platform_data/microchip-ksz.h>
 #include <linux/phy.h>
 #include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
 #include <net/dsa.h>
 #include <net/switchdev.h>
 
@@ -182,6 +183,29 @@ static void ksz9477_port_cfg32(struct ksz_device *dev, int port, int offset,
                           bits, set ? bits : 0);
 }
 
+static int ksz9477_change_mtu(struct dsa_switch *ds, int port, int mtu)
+{
+       struct ksz_device *dev = ds->priv;
+       u16 frame_size, max_frame = 0;
+       int i;
+
+       frame_size = mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
+
+       /* Cache the per-port MTU setting */
+       dev->ports[port].max_frame = frame_size;
+
+       for (i = 0; i < dev->port_cnt; i++)
+               max_frame = max(max_frame, dev->ports[i].max_frame);
+
+       return regmap_update_bits(dev->regmap[1], REG_SW_MTU__2,
+                                 REG_SW_MTU_MASK, max_frame);
+}
+
+static int ksz9477_max_mtu(struct dsa_switch *ds, 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;
@@ -1416,8 +1440,14 @@ static int ksz9477_setup(struct dsa_switch *ds)
        /* Do not work correctly with tail tagging. */
        ksz_cfg(dev, REG_SW_MAC_CTRL_0, SW_CHECK_LENGTH, false);
 
-       /* accept packet up to 2000bytes */
-       ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_LEGAL_PACKET_DISABLE, true);
+       /* Enable REG_SW_MTU__2 reg by setting SW_JUMBO_PACKET */
+       ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_JUMBO_PACKET, true);
+
+       /* Now we can configure default MTU value */
+       ret = regmap_update_bits(dev->regmap[1], REG_SW_MTU__2, REG_SW_MTU_MASK,
+                                VLAN_ETH_FRAME_LEN + ETH_FCS_LEN);
+       if (ret)
+               return ret;
 
        ksz9477_config_cpu_port(ds);
 
@@ -1464,6 +1494,8 @@ static const struct dsa_switch_ops ksz9477_switch_ops = {
        .port_mirror_add        = ksz9477_port_mirror_add,
        .port_mirror_del        = ksz9477_port_mirror_del,
        .get_stats64            = ksz9477_get_stats64,
+       .port_change_mtu        = ksz9477_change_mtu,
+       .port_max_mtu           = ksz9477_max_mtu,
 };
 
 static u32 ksz9477_get_port_addr(int port, int offset)

diff --git a/drivers/net/dsa/microchip/ksz9477_reg.h b/drivers/net/dsa/microchip/ksz9477_reg.h
index 16939f29faa5ec7f13de863bae18d973012209f4..0bd58467181f222074436b3e535384a3c59a7357 100644 (file)
--- a/drivers/net/dsa/microchip/ksz9477_reg.h
+++ b/drivers/net/dsa/microchip/ksz9477_reg.h
@@ -176,6 +176,7 @@
 #define REG_SW_MAC_ADDR_5              0x0307
 
 #define REG_SW_MTU__2                  0x0308
+#define REG_SW_MTU_MASK                        GENMASK(13, 0)
 
 #define REG_SW_ISP_TPID__2             0x030A
 
@@ -1662,4 +1663,6 @@
 /* 148,800 frames * 67 ms / 100 */
 #define BROADCAST_STORM_VALUE          9969
 
+#define KSZ9477_MAX_FRAME_SIZE         9000
+
 #endif /* KSZ9477_REGS_H */

diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 4ff0a159ce3c707e711b0f1c7b0aa9853fed505c..fa39ee73cbd2a13e003927973bcaea4a4e822ecf 100644 (file)
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -41,6 +41,7 @@ struct ksz_port {
 
        struct ksz_port_mib mib;
        phy_interface_t interface;
+       u16 max_frame;
 };
 
 struct ksz_device {