net: stmmac: refactor FPE verification process

Drop driver defined stmmac_fpe_state, and switch to common
ethtool_mm_verify_status for local TX verification status.

Local side and remote side verification processes are completely
independent. There is no reason at all to keep a local state and
a remote state.

Add a spinlock to avoid races among ISR, timer, link update
and register configuration.

This patch is based on Vladimir Oltean's proposal.

Vladimir Oltean says:

  ====================
  In the INITIAL state, the timer sends MPACKET_VERIFY. Eventually the
  stmmac_fpe_event_status() IRQ fires and advances the state to VERIFYING,
  then rearms the timer after verify_time ms. If a subsequent IRQ comes in
  and modifies the state to SUCCEEDED after getting MPACKET_RESPONSE, the
  timer sees this. It must enable the EFPE bit now. Otherwise, it
  decrements the verify_limit counter and tries again. Eventually it
  moves the status to FAILED, from which the IRQ cannot move it anywhere
  else, except for another stmmac_fpe_apply() call.
  ====================

Co-developed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://patch.msgid.link/151f86c8428eba967039718c6bf90a7d841e703b.1725631883.git.0x1207@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c

@@ -58,10 +58,6 @@ static void dwmac4_core_init(struct mac_device_info *hw,
 	if (hw->pcs)
 		value |= GMAC_PCS_IRQ_DEFAULT;
 
-	/* Enable FPE interrupt */
-	if ((GMAC_HW_FEAT_FPESEL & readl(ioaddr + GMAC_HW_FEATURE3)) >> 26)
-		value |= GMAC_INT_FPE_EN;
-
 	writel(value, ioaddr + GMAC_INT_EN);
 
 	if (GMAC_INT_DEFAULT_ENABLE & GMAC_INT_TSIE)

drivers/net/ethernet/stmicro/stmmac/dwmac5.c

@@ -575,11 +575,11 @@ int dwmac5_flex_pps_config(void __iomem *ioaddr, int index,
 
 void dwmac5_fpe_configure(void __iomem *ioaddr, struct stmmac_fpe_cfg *cfg,
 			  u32 num_txq, u32 num_rxq,
-			  bool enable)
+			  bool tx_enable, bool pmac_enable)
 {
 	u32 value;
 
-	if (enable) {
+	if (tx_enable) {
 		cfg->fpe_csr = EFPE;
 		value = readl(ioaddr + GMAC_RXQ_CTRL1);
 		value &= ~GMAC_RXQCTRL_FPRQ;
@@ -589,6 +589,21 @@ void dwmac5_fpe_configure(void __iomem *ioaddr, struct stmmac_fpe_cfg *cfg,
 		cfg->fpe_csr = 0;
 	}
 	writel(cfg->fpe_csr, ioaddr + MAC_FPE_CTRL_STS);
+
+	value = readl(ioaddr + GMAC_INT_EN);
+
+	if (pmac_enable) {
+		if (!(value & GMAC_INT_FPE_EN)) {
+			/* Dummy read to clear any pending masked interrupts */
+			readl(ioaddr + MAC_FPE_CTRL_STS);
+
+			value |= GMAC_INT_FPE_EN;
+		}
+	} else {
+		value &= ~GMAC_INT_FPE_EN;
+	}
+
+	writel(value, ioaddr + GMAC_INT_EN);
 }
 
 int dwmac5_fpe_irq_status(void __iomem *ioaddr, struct net_device *dev)

drivers/net/ethernet/stmicro/stmmac/dwmac5.h

@@ -104,7 +104,7 @@ int dwmac5_flex_pps_config(void __iomem *ioaddr, int index,
 			   u32 sub_second_inc, u32 systime_flags);
 void dwmac5_fpe_configure(void __iomem *ioaddr, struct stmmac_fpe_cfg *cfg,
 			  u32 num_txq, u32 num_rxq,
-			  bool enable);
+			  bool tx_enable, bool pmac_enable);
 void dwmac5_fpe_send_mpacket(void __iomem *ioaddr,
 			     struct stmmac_fpe_cfg *cfg,
 			     enum stmmac_mpacket_type type);

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c

@@ -1504,13 +1504,14 @@ static void dwxgmac2_set_arp_offload(struct mac_device_info *hw, bool en,
 	writel(value, ioaddr + XGMAC_RX_CONFIG);
 }
 
-static void dwxgmac3_fpe_configure(void __iomem *ioaddr, struct stmmac_fpe_cfg *cfg,
-				   u32 num_txq,
-				   u32 num_rxq, bool enable)
+static void dwxgmac3_fpe_configure(void __iomem *ioaddr,
+				   struct stmmac_fpe_cfg *cfg,
+				   u32 num_txq, u32 num_rxq,
+				   bool tx_enable, bool pmac_enable)
 {
 	u32 value;
 
-	if (!enable) {
+	if (!tx_enable) {
 		value = readl(ioaddr + XGMAC_FPE_CTRL_STS);
 
 		value &= ~XGMAC_EFPE;

drivers/net/ethernet/stmicro/stmmac/hwif.h

@@ -421,7 +421,7 @@ struct stmmac_ops {
 	void (*set_arp_offload)(struct mac_device_info *hw, bool en, u32 addr);
 	void (*fpe_configure)(void __iomem *ioaddr, struct stmmac_fpe_cfg *cfg,
 			      u32 num_txq, u32 num_rxq,
-			      bool enable);
+			      bool tx_enable, bool pmac_enable);
 	void (*fpe_send_mpacket)(void __iomem *ioaddr,
 				 struct stmmac_fpe_cfg *cfg,
 				 enum stmmac_mpacket_type type);

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -146,31 +146,30 @@ struct stmmac_channel {
 	u32 index;
 };
 
-/* FPE link state */
-enum stmmac_fpe_state {
-	FPE_STATE_OFF = 0,
-	FPE_STATE_CAPABLE = 1,
-	FPE_STATE_ENTERING_ON = 2,
-	FPE_STATE_ON = 3,
-};
-
 /* FPE link-partner hand-shaking mPacket type */
 enum stmmac_mpacket_type {
 	MPACKET_VERIFY = 0,
 	MPACKET_RESPONSE = 1,
 };
 
-enum stmmac_fpe_task_state_t {
-	__FPE_REMOVING,
-	__FPE_TASK_SCHED,
-};
+#define STMMAC_FPE_MM_MAX_VERIFY_RETRIES	3
+#define STMMAC_FPE_MM_MAX_VERIFY_TIME_MS	128
 
 struct stmmac_fpe_cfg {
-	bool enable;				/* FPE enable */
-	bool hs_enable;				/* FPE handshake enable */
-	enum stmmac_fpe_state lp_fpe_state;	/* Link Partner FPE state */
-	enum stmmac_fpe_state lo_fpe_state;	/* Local station FPE state */
+	/* Serialize access to MAC Merge state between ethtool requests
+	 * and link state updates.
+	 */
+	spinlock_t lock;
+
 	u32 fpe_csr;				/* MAC_FPE_CTRL_STS reg cache */
+
+	enum ethtool_mm_verify_status status;
+	struct timer_list verify_timer;
+	bool verify_enabled;
+	int verify_retries;
+	bool pmac_enabled;
+	u32 verify_time;
+	bool tx_enabled;
 };
 
 struct stmmac_tc_entry {
@@ -367,10 +366,6 @@ struct stmmac_priv {
 	struct work_struct service_task;
 
 	/* Frame Preemption feature (FPE) */
-	unsigned long fpe_task_state;
-	struct workqueue_struct *fpe_wq;
-	struct work_struct fpe_task;
-	char wq_name[IFNAMSIZ + 4];
 	struct stmmac_fpe_cfg fpe_cfg;
 
 	/* TC Handling */
@@ -425,6 +420,7 @@ bool stmmac_eee_init(struct stmmac_priv *priv);
 int stmmac_reinit_queues(struct net_device *dev, u32 rx_cnt, u32 tx_cnt);
 int stmmac_reinit_ringparam(struct net_device *dev, u32 rx_size, u32 tx_size);
 int stmmac_bus_clks_config(struct stmmac_priv *priv, bool enabled);
+void stmmac_fpe_apply(struct stmmac_priv *priv);
 
 static inline bool stmmac_xdp_is_enabled(struct stmmac_priv *priv)
 {