[PATCH net-next v5 1/2] net: ti: icssg-prueth: Add Frame Preemption MAC Merge support

[Meghana Malladi <m-malladi@ti.com>]

From: MD Danish Anwar <danishanwar@ti.com>

Introduce QoS infrastructure for Frame Preemption (FPE) support in
the ICSSG Ethernet driver.

prueth_qos_iet tracks FPE enable/active state and verify state machine
status via firmware-reported enum icssg_ietfpe_verify_states.
icssg_config_ietfpe() configures IET FPE in firmware, triggers
verify state machine based on ethtool MAC Merge parameters.
Polls firmware verify status up to 3 times with verify_time_ms intervals
and driver handles timeout by logging error and returning.

For MQPRIO qdisc support all queues are express by default later
gets override by user-provided preemptible_tcs bitmask via tc qdisc mask
Preempt mask configuration: Maps traffic classes to queue express/preemptible
state and applied only when FPE is active (Tx enabled)

Verify state machine re-triggers on link up/down events based on
fpe_enabled and fpe_active flags, and for memory protection, fpe_lock
serializes all FPE state mutations, preventing races between ethtool
config, qdisc setup, and link events

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
---

changes from v4(v5-v4):
- preemptible TCs are committed to hardware only when FPE is active
- Removed workqueue implementation with direct call to configure FPE
- Changed MAC verification logic to poll at verify_time_ms intervals
  instead of 5 seconds.
- Used mutex_lock whenever necessary to ensure proper synchronization
All the above changes are addressed as part of Vladimir Oltean <vladimir.oltean@nxp.com>
comments for this patch

 drivers/net/ethernet/ti/Makefile             |   3 +-
 drivers/net/ethernet/ti/icssg/icssg_config.h |   9 -
 drivers/net/ethernet/ti/icssg/icssg_prueth.c |   7 +
 drivers/net/ethernet/ti/icssg/icssg_prueth.h |   2 +
 drivers/net/ethernet/ti/icssg/icssg_qos.c    | 232 +++++++++++++++++++
 drivers/net/ethernet/ti/icssg/icssg_qos.h    |  68 ++++++
 6 files changed, 311 insertions(+), 10 deletions(-)
 create mode 100644 drivers/net/ethernet/ti/icssg/icssg_qos.c
 create mode 100644 drivers/net/ethernet/ti/icssg/icssg_qos.h

diff --git a/drivers/net/ethernet/ti/Makefile b/drivers/net/ethernet/ti/Makefile
index f4276c9a77620..d19bcd25c9d07 100644
--- a/drivers/net/ethernet/ti/Makefile
+++ b/drivers/net/ethernet/ti/Makefile
@@ -46,6 +46,7 @@ icssg-y := icssg/icssg_common.o \
 	   icssg/icssg_config.o \
 	   icssg/icssg_mii_cfg.o \
 	   icssg/icssg_stats.o \
-	   icssg/icssg_ethtool.o
+	   icssg/icssg_ethtool.o \
+	   icssg/icssg_qos.o
 
 obj-$(CONFIG_TI_ICSS_IEP) += icssg/icss_iep.o
diff --git a/drivers/net/ethernet/ti/icssg/icssg_config.h b/drivers/net/ethernet/ti/icssg/icssg_config.h
index 60d69744ffae2..1ac202f855ed4 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_config.h
+++ b/drivers/net/ethernet/ti/icssg/icssg_config.h
@@ -323,13 +323,4 @@ struct prueth_fdb_slot {
 	u8 fid;
 	u8 fid_c2;
 } __packed;
-
-enum icssg_ietfpe_verify_states {
-	ICSSG_IETFPE_STATE_UNKNOWN = 0,
-	ICSSG_IETFPE_STATE_INITIAL,
-	ICSSG_IETFPE_STATE_VERIFYING,
-	ICSSG_IETFPE_STATE_SUCCEEDED,
-	ICSSG_IETFPE_STATE_FAILED,
-	ICSSG_IETFPE_STATE_DISABLED
-};
 #endif /* __NET_TI_ICSSG_CONFIG_H */
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
index 591be5c8056b4..7657dc1015f0a 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
@@ -392,6 +392,8 @@ static void emac_adjust_link(struct net_device *ndev)
 		} else {
 			icssg_set_port_state(emac, ICSSG_EMAC_PORT_DISABLE);
 		}
+
+		icssg_qos_link_state_update(ndev);
 	}
 
 	if (emac->link) {
@@ -1652,6 +1654,7 @@ static const struct net_device_ops emac_netdev_ops = {
 	.ndo_hwtstamp_get = icssg_ndo_get_ts_config,
 	.ndo_hwtstamp_set = icssg_ndo_set_ts_config,
 	.ndo_xsk_wakeup = prueth_xsk_wakeup,
+	.ndo_setup_tc = icssg_qos_ndo_setup_tc,
 };
 
 static int prueth_netdev_init(struct prueth *prueth,
@@ -1686,6 +1689,8 @@ static int prueth_netdev_init(struct prueth *prueth,
 
 	INIT_DELAYED_WORK(&emac->stats_work, icssg_stats_work_handler);
 
+	icssg_qos_init(ndev);
+
 	ret = pruss_request_mem_region(prueth->pruss,
 				       port == PRUETH_PORT_MII0 ?
 				       PRUSS_MEM_DRAM0 : PRUSS_MEM_DRAM1,
@@ -2461,6 +2466,7 @@ static int prueth_probe(struct platform_device *pdev)
 		}
 		unregister_netdev(prueth->registered_netdevs[i]);
 		disable_work_sync(&prueth->emac[i]->rx_mode_work);
+		mutex_destroy(&prueth->emac[i]->qos.iet.fpe_lock);
 	}
 
 netdev_exit:
@@ -2521,6 +2527,7 @@ static void prueth_remove(struct platform_device *pdev)
 		prueth->emac[i]->ndev->phydev = NULL;
 		unregister_netdev(prueth->registered_netdevs[i]);
 		disable_work_sync(&prueth->emac[i]->rx_mode_work);
+		mutex_destroy(&prueth->emac[i]->qos.iet.fpe_lock);
 	}
 
 	for (i = 0; i < PRUETH_NUM_MACS; i++) {
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
index df93d15c5b786..85f7017d2c8e7 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
@@ -44,6 +44,7 @@
 #include "icssg_config.h"
 #include "icss_iep.h"
 #include "icssg_switch_map.h"
+#include "icssg_qos.h"
 
 #define PRUETH_MAX_MTU          (2000 - ETH_HLEN - ETH_FCS_LEN)
 #define PRUETH_MIN_PKT_SIZE     (VLAN_ETH_ZLEN)
@@ -254,6 +255,7 @@ struct prueth_emac {
 	struct bpf_prog *xdp_prog;
 	struct xdp_attachment_info xdpi;
 	int xsk_qid;
+	struct prueth_qos qos;
 };
 
 /* The buf includes headroom compatible with both skb and xdpf */
diff --git a/drivers/net/ethernet/ti/icssg/icssg_qos.c b/drivers/net/ethernet/ti/icssg/icssg_qos.c
new file mode 100644
index 0000000000000..fc4b0ebc7d683
--- /dev/null
+++ b/drivers/net/ethernet/ti/icssg/icssg_qos.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Texas Instruments ICSSG PRUETH QoS submodule
+ * Copyright (C) 2023 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#include "icssg_prueth.h"
+#include "icssg_switch_map.h"
+
+static void icssg_iet_set_preempt_mask(struct prueth_emac *emac)
+{
+	void __iomem *config = emac->dram.va + ICSSG_CONFIG_OFFSET;
+	struct prueth_qos_mqprio *p_mqprio = &emac->qos.mqprio;
+	struct tc_mqprio_qopt *qopt = &p_mqprio->mqprio.qopt;
+	u8 preemptible_tcs = p_mqprio->preemptible_tcs;
+	struct prueth_qos_iet *iet = &emac->qos.iet;
+	int prempt_mask = 0, i;
+	u8 tc;
+
+	/* The preemptible traffic classes should only be committed to hardware
+	 * once TX is active.
+	 */
+	if (!iet->fpe_active) {
+		netdev_dbg(emac->ndev, "FPE not active, skipping preempt mask config\n");
+		return;
+	}
+
+	/* Configure the queues based on the preemptible tc map set by the user */
+	for (tc = 0; tc < p_mqprio->mqprio.qopt.num_tc; tc++) {
+		/* check if the tc is preemptive or not */
+		if (preemptible_tcs & BIT(tc)) {
+			for (i = qopt->offset[tc]; i < qopt->offset[tc] + qopt->count[tc]; i++) {
+				/* Set all the queues in this tc as preemptive queues */
+				writeb(BIT(4), config + EXPRESS_PRE_EMPTIVE_Q_MAP + i);
+				prempt_mask &= ~BIT(i);
+			}
+		} else {
+			/* Set all the queues in this tc as express queues */
+			for (i = qopt->offset[tc]; i < qopt->offset[tc] + qopt->count[tc]; i++) {
+				writeb(0, config + EXPRESS_PRE_EMPTIVE_Q_MAP + i);
+				prempt_mask |= BIT(i);
+			}
+		}
+		netdev_set_tc_queue(emac->ndev, tc, qopt->count[tc], qopt->offset[tc]);
+	}
+	writeb(prempt_mask, config + EXPRESS_PRE_EMPTIVE_Q_MASK);
+}
+
+static int icssg_iet_verify_wait(struct prueth_emac *emac)
+{
+	void __iomem *config = emac->dram.va + ICSSG_CONFIG_OFFSET;
+	struct prueth_qos_iet *iet = &emac->qos.iet;
+	int try = 3;
+
+	do {
+		msleep(iet->verify_time_ms);
+		iet->verify_status = readb(config + PRE_EMPTION_VERIFY_STATUS);
+		if (iet->verify_status == ICSSG_IETFPE_STATE_SUCCEEDED)
+			return 0;
+	} while (--try > 0);
+
+	netdev_err(emac->ndev, "MAC Verify timeout\n");
+	return -ETIMEDOUT;
+}
+
+/* Direct synchronous configuration of IET FPE.
+ * Caller must hold iet->fpe_lock.
+ */
+void icssg_config_ietfpe(struct prueth_emac *emac, bool enable)
+{
+	void __iomem *config = emac->dram.va + ICSSG_CONFIG_OFFSET;
+	struct prueth_qos_iet *iet = &emac->qos.iet;
+	int ret;
+	u8 val;
+
+	/* return early if FPE is not active and need not be enabled */
+	if (!iet->fpe_enabled && !iet->fpe_active)
+		return;
+
+	if (!netif_running(emac->ndev)) {
+		netdev_dbg(emac->ndev, "cannot change IET/FPE state when interface is down\n");
+		return;
+	}
+
+	/* Update FPE Tx enable bit (PRE_EMPTION_ENABLE_TX) if
+	 * fpe_enabled is set to enable MM in Tx direction
+	 */
+	writeb(enable ? 1 : 0, config + PRE_EMPTION_ENABLE_TX);
+
+	/* If FPE is to be enabled, first configure MAC Verify state
+	 * machine in firmware as firmware kicks the Verify process
+	 * as soon as ICSSG_EMAC_PORT_PREMPT_TX_ENABLE command is
+	 * received.
+	 */
+	if (enable && iet->mac_verify_configure) {
+		writeb(1, config + PRE_EMPTION_ENABLE_VERIFY);
+		writew(iet->tx_min_frag_size, config + PRE_EMPTION_ADD_FRAG_SIZE_LOCAL);
+		writel(iet->verify_time_ms, config + PRE_EMPTION_VERIFY_TIME);
+	} else {
+		iet->verify_status = ICSSG_IETFPE_STATE_DISABLED;
+	}
+
+	/* Send command to enable FPE Tx side. Rx is always enabled */
+	ret = icssg_set_port_state(emac,
+				   enable ? ICSSG_EMAC_PORT_PREMPT_TX_ENABLE :
+					    ICSSG_EMAC_PORT_PREMPT_TX_DISABLE);
+	if (ret) {
+		netdev_err(emac->ndev, "TX preempt %s command failed\n",
+			   str_enable_disable(enable));
+		writeb(0, config + PRE_EMPTION_ENABLE_VERIFY);
+		iet->verify_status = ICSSG_IETFPE_STATE_DISABLED;
+		return;
+	}
+
+	if (enable && iet->mac_verify_configure) {
+		ret = icssg_iet_verify_wait(emac);
+		if (ret) {
+			netdev_err(emac->ndev, "MAC Verification failed with timeout\n");
+			return;
+		}
+	} else if (enable) {
+		/* Give firmware some time to update PRE_EMPTION_ACTIVE_TX state */
+		usleep_range(100, 200);
+	}
+
+	if (enable) {
+		val = readb(config + PRE_EMPTION_ACTIVE_TX);
+		if (val != 1) {
+			netdev_err(emac->ndev,
+				   "Firmware fails to activate IET/FPE\n");
+			return;
+		}
+		iet->fpe_active = true;
+	} else {
+		iet->fpe_active = false;
+	}
+
+	icssg_iet_set_preempt_mask(emac);
+	netdev_err(emac->ndev, "IET FPE %s successfully\n",
+		  str_enable_disable(iet->fpe_active));
+}
+EXPORT_SYMBOL_GPL(icssg_config_ietfpe);
+
+void icssg_qos_init(struct net_device *ndev)
+{
+	struct prueth_emac *emac = netdev_priv(ndev);
+	struct prueth_qos_iet *iet = &emac->qos.iet;
+
+	iet->emac = emac;
+	mutex_init(&iet->fpe_lock);
+}
+
+static void icssg_iet_change_preemptible_tcs(struct prueth_emac *emac)
+{
+	struct prueth_qos_iet *iet = &emac->qos.iet;
+
+	mutex_lock(&iet->fpe_lock);
+	icssg_config_ietfpe(emac, iet->fpe_enabled);
+	mutex_unlock(&iet->fpe_lock);
+}
+
+static int emac_tc_query_caps(struct net_device *ndev, void *type_data)
+{
+	struct tc_query_caps_base *base = type_data;
+
+	switch (base->type) {
+	case TC_SETUP_QDISC_MQPRIO: {
+		struct tc_mqprio_caps *caps = base->caps;
+
+		caps->validate_queue_counts = true;
+		return 0;
+	}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int emac_tc_setup_mqprio(struct net_device *ndev, void *type_data)
+{
+	struct tc_mqprio_qopt_offload *mqprio = type_data;
+	struct prueth_emac *emac = netdev_priv(ndev);
+	struct tc_mqprio_qopt *qopt = &mqprio->qopt;
+	struct prueth_qos_mqprio *p_mqprio;
+	u8 num_tc = mqprio->qopt.num_tc;
+	int tc, offset, count;
+
+	p_mqprio = &emac->qos.mqprio;
+
+	if (!num_tc) {
+		netdev_reset_tc(ndev);
+		p_mqprio->preemptible_tcs = 0;
+		p_mqprio->mqprio.qopt.num_tc = 0;
+		goto reset_tcs;
+	}
+
+	memcpy(&p_mqprio->mqprio, mqprio, sizeof(*mqprio));
+	p_mqprio->preemptible_tcs = mqprio->preemptible_tcs;
+	netdev_set_num_tc(ndev, mqprio->qopt.num_tc);
+
+	for (tc = 0; tc < num_tc; tc++) {
+		count = qopt->count[tc];
+		offset = qopt->offset[tc];
+		netdev_set_tc_queue(ndev, tc, count, offset);
+	}
+
+reset_tcs:
+	icssg_iet_change_preemptible_tcs(emac);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(icssg_qos_init);
+
+int icssg_qos_ndo_setup_tc(struct net_device *ndev, enum tc_setup_type type,
+			   void *type_data)
+{
+	switch (type) {
+	case TC_QUERY_CAPS:
+		return emac_tc_query_caps(ndev, type_data);
+	case TC_SETUP_QDISC_MQPRIO:
+		return emac_tc_setup_mqprio(ndev, type_data);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+EXPORT_SYMBOL_GPL(icssg_qos_ndo_setup_tc);
+
+void icssg_qos_link_state_update(struct net_device *ndev)
+{
+	struct prueth_emac *emac = netdev_priv(ndev);
+
+	icssg_iet_change_preemptible_tcs(emac);
+}
+EXPORT_SYMBOL_GPL(icssg_qos_link_state_update);
diff --git a/drivers/net/ethernet/ti/icssg/icssg_qos.h b/drivers/net/ethernet/ti/icssg/icssg_qos.h
new file mode 100644
index 0000000000000..083f248c557de
--- /dev/null
+++ b/drivers/net/ethernet/ti/icssg/icssg_qos.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2023 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#ifndef __NET_TI_ICSSG_QOS_H
+#define __NET_TI_ICSSG_QOS_H
+
+#include <linux/atomic.h>
+#include <linux/netdevice.h>
+#include <net/pkt_sched.h>
+
+/**
+ * enum icssg_ietfpe_verify_states - status of MAC Merge Verify returned by firmware
+ * @ICSSG_IETFPE_STATE_UNKNOWN:
+ *	verification status is unknown
+ * @ICSSG_IETFPE_STATE_INITIAL:
+ *	Firmware returns this if verify state diagram is idle
+ * @ICSSG_IETFPE_STATE_VERIFYING:
+ *	Firmware returns this if verification is ongoing
+ * @ICSSG_IETFPE_STATE_SUCCEEDED:
+ *	Firmware returns this if verify state diagram completes verification
+ * @ICSSG_IETFPE_STATE_FAILED:
+ *	Firmware returns this if verify state diagram fails during verification
+ * @ICSSG_IETFPE_STATE_DISABLED:
+ *	verification is disabled by the driver
+ */
+enum icssg_ietfpe_verify_states {
+	ICSSG_IETFPE_STATE_UNKNOWN = 0,
+	ICSSG_IETFPE_STATE_INITIAL,
+	ICSSG_IETFPE_STATE_VERIFYING,
+	ICSSG_IETFPE_STATE_SUCCEEDED,
+	ICSSG_IETFPE_STATE_FAILED,
+	ICSSG_IETFPE_STATE_DISABLED
+};
+
+struct prueth_qos_mqprio {
+	struct tc_mqprio_qopt_offload mqprio;
+	u8 preemptible_tcs;
+};
+
+struct prueth_qos_iet {
+	struct prueth_emac *emac;
+
+	/* Configuration state - protected by fpe_lock */
+	bool fpe_enabled;
+	bool mac_verify_configure;
+	u32 tx_min_frag_size;
+	u32 verify_time_ms;
+
+	/* Runtime state - protected by fpe_lock */
+	bool fpe_active;
+	enum icssg_ietfpe_verify_states verify_status;
+
+	/* Synchronization: single mutex protects all FPE operations */
+	struct mutex fpe_lock;
+};
+
+struct prueth_qos {
+	struct prueth_qos_iet iet;
+	struct prueth_qos_mqprio mqprio;
+};
+
+void icssg_qos_init(struct net_device *ndev);
+void icssg_qos_link_state_update(struct net_device *ndev);
+int icssg_qos_ndo_setup_tc(struct net_device *ndev, enum tc_setup_type type,
+			   void *type_data);
+void icssg_config_ietfpe(struct prueth_emac *emac, bool enable);
+#endif /* __NET_TI_ICSSG_QOS_H */
-- 
2.43.0