net: stmmac: Enable EEE HW LPI timer with auto SW/HW switching

This patch enables the HW LPI Timer which controls the automatic entry
and exit of the LPI state.
The EEE LPI timer value is configured through ethtool. The driver will
auto select the LPI HW timer if the value in the HW timer supported range.
Else, the driver will fallback to SW timer.

Signed-off-by: Vineetha G. Jaya Kumaran <[e-mail]>
Signed-off-by: Voon Weifeng <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 /* Default LPI timers */
 #define STMMAC_DEFAULT_LIT_LS	0x3E8
 #define STMMAC_DEFAULT_TWT_LS	0x1E
+#define STMMAC_ET_MAX		0xFFFFF
 
 #define STMMAC_CHAIN_MODE	0x1
 #define STMMAC_RING_MODE	0x2

drivers/net/ethernet/stmicro/stmmac/dwmac4.h

···
  */
 #define GMAC4_LPI_CTRL_STATUS	0xd0
 #define GMAC4_LPI_TIMER_CTRL	0xd4
+#define GMAC4_LPI_ENTRY_TIMER	0xd8
 
 /* LPI control and status defines */
 #define GMAC4_LPI_CTRL_STATUS_LPITCSE	BIT(21)	/* LPI Tx Clock Stop Enable */
+#define GMAC4_LPI_CTRL_STATUS_LPIATE	BIT(20) /* LPI Timer Enable */
 #define GMAC4_LPI_CTRL_STATUS_LPITXA	BIT(19)	/* Enable LPI TX Automate */
 #define GMAC4_LPI_CTRL_STATUS_PLS	BIT(17) /* PHY Link Status */
 #define GMAC4_LPI_CTRL_STATUS_LPIEN	BIT(16)	/* LPI Enable */

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

···
 	writel(value, ioaddr + GMAC4_LPI_CTRL_STATUS);
 }
 
+static void dwmac4_set_eee_lpi_entry_timer(struct mac_device_info *hw, int et)
+{
+	void __iomem *ioaddr = hw->pcsr;
+	int value = et & STMMAC_ET_MAX;
+	int regval;
+
+	/* Program LPI entry timer value into register */
+	writel(value, ioaddr + GMAC4_LPI_ENTRY_TIMER);
+
+	/* Enable/disable LPI entry timer */
+	regval = readl(ioaddr + GMAC4_LPI_CTRL_STATUS);
+	regval |= GMAC4_LPI_CTRL_STATUS_LPIEN | GMAC4_LPI_CTRL_STATUS_LPITXA;
+
+	if (et)
+		regval |= GMAC4_LPI_CTRL_STATUS_LPIATE;
+	else
+		regval &= ~GMAC4_LPI_CTRL_STATUS_LPIATE;
+
+	writel(regval, ioaddr + GMAC4_LPI_CTRL_STATUS);
+}
+
 static void dwmac4_set_eee_timer(struct mac_device_info *hw, int ls, int tw)
 {
 	void __iomem *ioaddr = hw->pcsr;
···
 	.get_umac_addr = dwmac4_get_umac_addr,
 	.set_eee_mode = dwmac4_set_eee_mode,
 	.reset_eee_mode = dwmac4_reset_eee_mode,
+	.set_eee_lpi_entry_timer = dwmac4_set_eee_lpi_entry_timer,
 	.set_eee_timer = dwmac4_set_eee_timer,
 	.set_eee_pls = dwmac4_set_eee_pls,
 	.pcs_ctrl_ane = dwmac4_ctrl_ane,
···
 	.get_umac_addr = dwmac4_get_umac_addr,
 	.set_eee_mode = dwmac4_set_eee_mode,
 	.reset_eee_mode = dwmac4_reset_eee_mode,
+	.set_eee_lpi_entry_timer = dwmac4_set_eee_lpi_entry_timer,
 	.set_eee_timer = dwmac4_set_eee_timer,
 	.set_eee_pls = dwmac4_set_eee_pls,
 	.pcs_ctrl_ane = dwmac4_ctrl_ane,
···
 	.get_umac_addr = dwmac4_get_umac_addr,
 	.set_eee_mode = dwmac4_set_eee_mode,
 	.reset_eee_mode = dwmac4_reset_eee_mode,
+	.set_eee_lpi_entry_timer = dwmac4_set_eee_lpi_entry_timer,
 	.set_eee_timer = dwmac4_set_eee_timer,
 	.set_eee_pls = dwmac4_set_eee_pls,
 	.pcs_ctrl_ane = dwmac4_ctrl_ane,

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

···
 	void (*set_eee_mode)(struct mac_device_info *hw,
 			     bool en_tx_lpi_clockgating);
 	void (*reset_eee_mode)(struct mac_device_info *hw);
+	void (*set_eee_lpi_entry_timer)(struct mac_device_info *hw, int et);
 	void (*set_eee_timer)(struct mac_device_info *hw, int ls, int tw);
 	void (*set_eee_pls)(struct mac_device_info *hw, int link);
 	void (*debug)(void __iomem *ioaddr, struct stmmac_extra_stats *x,
···
 	stmmac_do_void_callback(__priv, mac, set_eee_mode, __args)
 #define stmmac_reset_eee_mode(__priv, __args...) \
 	stmmac_do_void_callback(__priv, mac, reset_eee_mode, __args)
+#define stmmac_set_eee_lpi_timer(__priv, __args...) \
+	stmmac_do_void_callback(__priv, mac, set_eee_lpi_entry_timer, __args)
 #define stmmac_set_eee_timer(__priv, __args...) \
 	stmmac_do_void_callback(__priv, mac, set_eee_timer, __args)
 #define stmmac_set_eee_pls(__priv, __args...) \

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

···
 	int tx_lpi_timer;
 	int tx_lpi_enabled;
 	int eee_tw_timer;
+	bool eee_sw_timer_en;
 	unsigned int mode;
 	unsigned int chain_mode;
 	int extend_desc;

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

···
 	return dirty;
 }
 
+static void stmmac_lpi_entry_timer_config(struct stmmac_priv *priv, bool en)
+{
+	int tx_lpi_timer;
+
+	/* Clear/set the SW EEE timer flag based on LPI ET enablement */
+	priv->eee_sw_timer_en = en ? 0 : 1;
+	tx_lpi_timer  = en ? priv->tx_lpi_timer : 0;
+	stmmac_set_eee_lpi_timer(priv, priv->hw, tx_lpi_timer);
+}
+
 /**
  * stmmac_enable_eee_mode - check and enter in LPI mode
  * @priv: driver private structure
···
  */
 void stmmac_disable_eee_mode(struct stmmac_priv *priv)
 {
+	if (!priv->eee_sw_timer_en) {
+		stmmac_lpi_entry_timer_config(priv, 0);
+		return;
+	}
+
 	stmmac_reset_eee_mode(priv, priv->hw);
 	del_timer_sync(&priv->eee_ctrl_timer);
 	priv->tx_path_in_lpi_mode = false;
···
 	if (!priv->eee_active) {
 		if (priv->eee_enabled) {
 			netdev_dbg(priv->dev, "disable EEE\n");
+			stmmac_lpi_entry_timer_config(priv, 0);
 			del_timer_sync(&priv->eee_ctrl_timer);
 			stmmac_set_eee_timer(priv, priv->hw, 0, eee_tw_timer);
 		}
···
 				     eee_tw_timer);
 	}
 
-	mod_timer(&priv->eee_ctrl_timer, STMMAC_LPI_T(priv->tx_lpi_timer));
+	if (priv->plat->has_gmac4 && priv->tx_lpi_timer <= STMMAC_ET_MAX) {
+		del_timer_sync(&priv->eee_ctrl_timer);
+		priv->tx_path_in_lpi_mode = false;
+		stmmac_lpi_entry_timer_config(priv, 1);
+	} else {
+		stmmac_lpi_entry_timer_config(priv, 0);
+		mod_timer(&priv->eee_ctrl_timer,
+			  STMMAC_LPI_T(priv->tx_lpi_timer));
+	}
 
 	mutex_unlock(&priv->lock);
 	netdev_dbg(priv->dev, "Energy-Efficient Ethernet initialized\n");
···
 		netif_tx_wake_queue(netdev_get_tx_queue(priv->dev, queue));
 	}
 
-	if ((priv->eee_enabled) && (!priv->tx_path_in_lpi_mode)) {
+	if (priv->eee_enabled && !priv->tx_path_in_lpi_mode &&
+	    priv->eee_sw_timer_en) {
 		stmmac_enable_eee_mode(priv);
 		mod_timer(&priv->eee_ctrl_timer, STMMAC_LPI_T(priv->tx_lpi_timer));
 	}
···
 	tx_q = &priv->tx_queue[queue];
 	first_tx = tx_q->cur_tx;
 
-	if (priv->tx_path_in_lpi_mode)
+	if (priv->tx_path_in_lpi_mode && priv->eee_sw_timer_en)
 		stmmac_disable_eee_mode(priv);
 
 	/* Manage oversized TCP frames for GMAC4 device */