net: ethtool: mm: extract stmmac verification logic into common library

It appears that stmmac is not the only hardware which requires a
software-driven verification state machine for the MAC Merge layer.

While on the one hand it's good to encourage hardware implementations,
on the other hand it's quite difficult to tolerate multiple drivers
implementing independently fairly non-trivial logic.

Extract the hardware-independent logic from stmmac into library code and
put it in ethtool. Name the state structure "mmsv" for MAC Merge
Software Verification. Let this expose an operations structure for
executing the hardware stuff: sync hardware with the tx_active boolean
(result of verification process), enable/disable the pMAC, send mPackets,
notify library of external events (reception of mPackets), as well as
link state changes.

Note that it is assumed that the external events are received in hardirq
context. If they are not, it is probably a good idea to disable hardirqs
when calling ethtool_mmsv_event_handle(), because the library does not
do so.

Also, the MM software verification process has no business with the
tx_min_frag_size, that is all the driver's to handle.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Co-developed-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
Signed-off-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
Tested-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
Tested-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 274 insertions, 1 deletions

diff --git a/net/ethtool/mm.c b/net/ethtool/mm.c
index 2816bb23c3ad..bfd988464d7d 100644
--- a/net/ethtool/mm.c
+++ b/net/ethtool/mm.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright 2022-2023 NXP
+ * Copyright 2022-2025 NXP
+ * Copyright 2024 Furong Xu <0x1207@gmail.com>
  */
 #include "common.h"
 #include "netlink.h"
@@ -282,3 +283,275 @@ bool ethtool_dev_mm_supported(struct net_device *dev)
 	return supported;
 }
 EXPORT_SYMBOL_GPL(ethtool_dev_mm_supported);
+
+static void ethtool_mmsv_configure_tx(struct ethtool_mmsv *mmsv,
+				      bool tx_active)
+{
+	if (mmsv->ops->configure_tx)
+		mmsv->ops->configure_tx(mmsv, tx_active);
+}
+
+static void ethtool_mmsv_configure_pmac(struct ethtool_mmsv *mmsv,
+					bool pmac_enabled)
+{
+	if (mmsv->ops->configure_pmac)
+		mmsv->ops->configure_pmac(mmsv, pmac_enabled);
+}
+
+static void ethtool_mmsv_send_mpacket(struct ethtool_mmsv *mmsv,
+				      enum ethtool_mpacket mpacket)
+{
+	if (mmsv->ops->send_mpacket)
+		mmsv->ops->send_mpacket(mmsv, mpacket);
+}
+
+/**
+ * ethtool_mmsv_verify_timer - Timer for MAC Merge verification
+ * @t: timer_list struct containing private info
+ *
+ * Verify the MAC Merge capability in the local TX direction, by
+ * transmitting Verify mPackets up to 3 times. Wait until link
+ * partner responds with a Response mPacket, otherwise fail.
+ */
+static void ethtool_mmsv_verify_timer(struct timer_list *t)
+{
+	struct ethtool_mmsv *mmsv = from_timer(mmsv, t, verify_timer);
+	unsigned long flags;
+	bool rearm = false;
+
+	spin_lock_irqsave(&mmsv->lock, flags);
+
+	switch (mmsv->status) {
+	case ETHTOOL_MM_VERIFY_STATUS_INITIAL:
+	case ETHTOOL_MM_VERIFY_STATUS_VERIFYING:
+		if (mmsv->verify_retries != 0) {
+			ethtool_mmsv_send_mpacket(mmsv, ETHTOOL_MPACKET_VERIFY);
+			rearm = true;
+		} else {
+			mmsv->status = ETHTOOL_MM_VERIFY_STATUS_FAILED;
+		}
+
+		mmsv->verify_retries--;
+		break;
+
+	case ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED:
+		ethtool_mmsv_configure_tx(mmsv, true);
+		break;
+
+	default:
+		break;
+	}
+
+	if (rearm) {
+		mod_timer(&mmsv->verify_timer,
+			  jiffies + msecs_to_jiffies(mmsv->verify_time));
+	}
+
+	spin_unlock_irqrestore(&mmsv->lock, flags);
+}
+
+static void ethtool_mmsv_verify_timer_arm(struct ethtool_mmsv *mmsv)
+{
+	if (mmsv->pmac_enabled && mmsv->tx_enabled && mmsv->verify_enabled &&
+	    mmsv->status != ETHTOOL_MM_VERIFY_STATUS_FAILED &&
+	    mmsv->status != ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED) {
+		timer_setup(&mmsv->verify_timer, ethtool_mmsv_verify_timer, 0);
+		mod_timer(&mmsv->verify_timer, jiffies);
+	}
+}
+
+static void ethtool_mmsv_apply(struct ethtool_mmsv *mmsv)
+{
+	/* If verification is disabled, configure FPE right away.
+	 * Otherwise let the timer code do it.
+	 */
+	if (!mmsv->verify_enabled) {
+		ethtool_mmsv_configure_pmac(mmsv, mmsv->pmac_enabled);
+		ethtool_mmsv_configure_tx(mmsv, mmsv->tx_enabled);
+	} else {
+		mmsv->status = ETHTOOL_MM_VERIFY_STATUS_INITIAL;
+		mmsv->verify_retries = ETHTOOL_MM_MAX_VERIFY_RETRIES;
+
+		if (netif_running(mmsv->dev))
+			ethtool_mmsv_verify_timer_arm(mmsv);
+	}
+}
+
+/**
+ * ethtool_mmsv_stop() - Stop MAC Merge Software Verification
+ * @mmsv: MAC Merge Software Verification state
+ *
+ * Drivers should call this method in a state where the hardware is
+ * about to lose state, like ndo_stop() or suspend(), and turning off
+ * MAC Merge features would be superfluous. Otherwise, prefer
+ * ethtool_mmsv_link_state_handle() with up=false.
+ */
+void ethtool_mmsv_stop(struct ethtool_mmsv *mmsv)
+{
+	timer_shutdown_sync(&mmsv->verify_timer);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_stop);
+
+/**
+ * ethtool_mmsv_link_state_handle() - Inform MAC Merge Software Verification
+ *				      of link state changes
+ * @mmsv: MAC Merge Software Verification state
+ * @up: True if device carrier is up and able to pass verification packets
+ *
+ * Calling context is expected to be from a task, interrupts enabled.
+ */
+void ethtool_mmsv_link_state_handle(struct ethtool_mmsv *mmsv, bool up)
+{
+	unsigned long flags;
+
+	ethtool_mmsv_stop(mmsv);
+
+	spin_lock_irqsave(&mmsv->lock, flags);
+
+	if (up && mmsv->pmac_enabled) {
+		/* VERIFY process requires pMAC enabled when NIC comes up */
+		ethtool_mmsv_configure_pmac(mmsv, true);
+
+		/* New link => maybe new partner => new verification process */
+		ethtool_mmsv_apply(mmsv);
+	} else {
+		/* No link or pMAC not enabled */
+		ethtool_mmsv_configure_pmac(mmsv, false);
+		ethtool_mmsv_configure_tx(mmsv, false);
+	}
+
+	spin_unlock_irqrestore(&mmsv->lock, flags);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_link_state_handle);
+
+/**
+ * ethtool_mmsv_event_handle() - Inform MAC Merge Software Verification
+ *				 of interrupt-based events
+ * @mmsv: MAC Merge Software Verification state
+ * @event: Event which took place (packet transmission or reception)
+ *
+ * Calling context expects to have interrupts disabled.
+ */
+void ethtool_mmsv_event_handle(struct ethtool_mmsv *mmsv,
+			       enum ethtool_mmsv_event event)
+{
+	/* This is interrupt context, just spin_lock() */
+	spin_lock(&mmsv->lock);
+
+	if (!mmsv->pmac_enabled)
+		goto unlock;
+
+	switch (event) {
+	case ETHTOOL_MMSV_LP_SENT_VERIFY_MPACKET:
+		/* Link partner has sent verify mPacket */
+		ethtool_mmsv_send_mpacket(mmsv, ETHTOOL_MPACKET_RESPONSE);
+		break;
+	case ETHTOOL_MMSV_LD_SENT_VERIFY_MPACKET:
+		/* Local device has sent verify mPacket */
+		if (mmsv->status != ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED)
+			mmsv->status = ETHTOOL_MM_VERIFY_STATUS_VERIFYING;
+		break;
+	case ETHTOOL_MMSV_LP_SENT_RESPONSE_MPACKET:
+		/* Link partner has sent response mPacket */
+		if (mmsv->status == ETHTOOL_MM_VERIFY_STATUS_VERIFYING)
+			mmsv->status = ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED;
+		break;
+	}
+
+unlock:
+	spin_unlock(&mmsv->lock);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_event_handle);
+
+static bool ethtool_mmsv_is_tx_active(struct ethtool_mmsv *mmsv)
+{
+	/* TX is active if administratively enabled, and verification either
+	 * succeeded, or was administratively disabled.
+	 */
+	return mmsv->tx_enabled &&
+	       (mmsv->status == ETHTOOL_MM_VERIFY_STATUS_SUCCEEDED ||
+	       mmsv->status == ETHTOOL_MM_VERIFY_STATUS_DISABLED);
+}
+
+/**
+ * ethtool_mmsv_get_mm() - get_mm() hook for MAC Merge Software Verification
+ * @mmsv: MAC Merge Software Verification state
+ * @state: see struct ethtool_mm_state
+ *
+ * Drivers are expected to call this from their ethtool_ops :: get_mm()
+ * method.
+ */
+void ethtool_mmsv_get_mm(struct ethtool_mmsv *mmsv,
+			 struct ethtool_mm_state *state)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&mmsv->lock, flags);
+
+	state->max_verify_time = ETHTOOL_MM_MAX_VERIFY_TIME_MS;
+	state->verify_enabled = mmsv->verify_enabled;
+	state->pmac_enabled = mmsv->pmac_enabled;
+	state->verify_time = mmsv->verify_time;
+	state->tx_enabled = mmsv->tx_enabled;
+	state->verify_status = mmsv->status;
+	state->tx_active = ethtool_mmsv_is_tx_active(mmsv);
+
+	spin_unlock_irqrestore(&mmsv->lock, flags);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_get_mm);
+
+/**
+ * ethtool_mmsv_set_mm() - set_mm() hook for MAC Merge Software Verification
+ * @mmsv: MAC Merge Software Verification state
+ * @cfg: see struct ethtool_mm_cfg
+ *
+ * Drivers are expected to call this from their ethtool_ops :: set_mm()
+ * method.
+ */
+void ethtool_mmsv_set_mm(struct ethtool_mmsv *mmsv, struct ethtool_mm_cfg *cfg)
+{
+	unsigned long flags;
+
+	/* Wait for the verification that's currently in progress to finish */
+	ethtool_mmsv_stop(mmsv);
+
+	spin_lock_irqsave(&mmsv->lock, flags);
+
+	mmsv->verify_enabled = cfg->verify_enabled;
+	mmsv->pmac_enabled = cfg->pmac_enabled;
+	mmsv->verify_time = cfg->verify_time;
+	mmsv->tx_enabled = cfg->tx_enabled;
+
+	if (!cfg->verify_enabled)
+		mmsv->status = ETHTOOL_MM_VERIFY_STATUS_DISABLED;
+
+	ethtool_mmsv_apply(mmsv);
+
+	spin_unlock_irqrestore(&mmsv->lock, flags);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_set_mm);
+
+/**
+ * ethtool_mmsv_init() - Initialize MAC Merge Software Verification state
+ * @mmsv: MAC Merge Software Verification state
+ * @dev: Pointer to network interface
+ * @ops: Methods for implementing the generic functionality
+ *
+ * The MAC Merge Software Verification is a timer- and event-based state
+ * machine intended for network interfaces which lack a hardware-based
+ * TX verification process (as per IEEE 802.3 clause 99.4.3). The timer
+ * is managed by the core code, whereas events are supplied by the
+ * driver explicitly calling one of the other API functions.
+ */
+void ethtool_mmsv_init(struct ethtool_mmsv *mmsv, struct net_device *dev,
+		       const struct ethtool_mmsv_ops *ops)
+{
+	mmsv->ops = ops;
+	mmsv->dev = dev;
+	mmsv->verify_retries = ETHTOOL_MM_MAX_VERIFY_RETRIES;
+	mmsv->verify_time = ETHTOOL_MM_MAX_VERIFY_TIME_MS;
+	mmsv->status = ETHTOOL_MM_VERIFY_STATUS_DISABLED;
+	timer_setup(&mmsv->verify_timer, ethtool_mmsv_verify_timer, 0);
+	spin_lock_init(&mmsv->lock);
+}
+EXPORT_SYMBOL_GPL(ethtool_mmsv_init);