net: dsa: microchip: Enable HSR offloading for KSZ9477

This patch adds functions for providing in KSZ9477 switch HSR
(High-availability Seamless Redundancy) hardware offloading.

According to AN3474 application note following features are provided:
- TX packet duplication from host to switch (NETIF_F_HW_HSR_DUP)
- RX packet duplication discarding
- Prevention of packet loop

For last two ones - there is a probability that some packets will not
be filtered in HW (in some special cases - described in AN3474).
Hence, the HSR core code shall be used to discard those not caught frames.

Moreover, some switch registers adjustments are required - like setting
MAC address of HSR network interface.

Additionally, the KSZ9477 switch has been configured to forward frames
between HSR ports (e.g. 1,2) members to provide support for
NETIF_F_HW_HSR_FWD flag.

Join and leave functions are written in a way, that are executed with
single port - i.e. configuration is NOT done only when second HSR port
is configured.

Co-developed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 77 insertions, 0 deletions

diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
index 9e63ed820c92..cde8ef33d029 100644
--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -1143,6 +1143,83 @@ int ksz9477_tc_cbs_set_cinc(struct ksz_device *dev, int port, u32 val)
 	return ksz_pwrite16(dev, port, REG_PORT_MTI_CREDIT_INCREMENT, val);
 }
 
+/* The KSZ9477 provides following HW features to accelerate
+ * HSR frames handling:
+ *
+ * 1. TX PACKET DUPLICATION FROM HOST TO SWITCH
+ * 2. RX PACKET DUPLICATION DISCARDING
+ * 3. PREVENTING PACKET LOOP IN THE RING BY SELF-ADDRESS FILTERING
+ *
+ * Only one from point 1. has the NETIF_F* flag available.
+ *
+ * Ones from point 2 and 3 are "best effort" - i.e. those will
+ * work correctly most of the time, but it may happen that some
+ * frames will not be caught - to be more specific; there is a race
+ * condition in hardware such that, when duplicate packets are received
+ * on member ports very close in time to each other, the hardware fails
+ * to detect that they are duplicates.
+ *
+ * Hence, the SW needs to handle those special cases. However, the speed
+ * up gain is considerable when above features are used.
+ *
+ * Moreover, the NETIF_F_HW_HSR_FWD feature is also enabled, as HSR frames
+ * can be forwarded in the switch fabric between HSR ports.
+ */
+#define KSZ9477_SUPPORTED_HSR_FEATURES (NETIF_F_HW_HSR_DUP | NETIF_F_HW_HSR_FWD)
+
+void ksz9477_hsr_join(struct dsa_switch *ds, int port, struct net_device *hsr)
+{
+	struct ksz_device *dev = ds->priv;
+	struct net_device *slave;
+	struct dsa_port *hsr_dp;
+	u8 data, hsr_ports = 0;
+
+	/* Program which port(s) shall support HSR */
+	ksz_rmw32(dev, REG_HSR_PORT_MAP__4, BIT(port), BIT(port));
+
+	/* Forward frames between HSR ports (i.e. bridge together HSR ports) */
+	if (dev->hsr_ports) {
+		dsa_hsr_foreach_port(hsr_dp, ds, hsr)
+			hsr_ports |= BIT(hsr_dp->index);
+
+		hsr_ports |= BIT(dsa_upstream_port(ds, port));
+		dsa_hsr_foreach_port(hsr_dp, ds, hsr)
+			ksz9477_cfg_port_member(dev, hsr_dp->index, hsr_ports);
+	}
+
+	if (!dev->hsr_ports) {
+		/* Enable discarding of received HSR frames */
+		ksz_read8(dev, REG_HSR_ALU_CTRL_0__1, &data);
+		data |= HSR_DUPLICATE_DISCARD;
+		data &= ~HSR_NODE_UNICAST;
+		ksz_write8(dev, REG_HSR_ALU_CTRL_0__1, data);
+	}
+
+	/* Enable per port self-address filtering.
+	 * The global self-address filtering has already been enabled in the
+	 * ksz9477_reset_switch() function.
+	 */
+	ksz_port_cfg(dev, port, REG_PORT_LUE_CTRL, PORT_SRC_ADDR_FILTER, true);
+
+	/* Setup HW supported features for lan HSR ports */
+	slave = dsa_to_port(ds, port)->slave;
+	slave->features |= KSZ9477_SUPPORTED_HSR_FEATURES;
+}
+
+void ksz9477_hsr_leave(struct dsa_switch *ds, int port, struct net_device *hsr)
+{
+	struct ksz_device *dev = ds->priv;
+
+	/* Clear port HSR support */
+	ksz_rmw32(dev, REG_HSR_PORT_MAP__4, BIT(port), 0);
+
+	/* Disable forwarding frames between HSR ports */
+	ksz9477_cfg_port_member(dev, port, BIT(dsa_upstream_port(ds, port)));
+
+	/* Disable per port self-address filtering */
+	ksz_port_cfg(dev, port, REG_PORT_LUE_CTRL, PORT_SRC_ADDR_FILTER, false);
+}
+
 int ksz9477_switch_init(struct ksz_device *dev)
 {
 	u8 data8;