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

Meghana Malladi
2026-04-30T11:17:35Z

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