commit 45b679c9a3ccd9e34f28e6ec677b812a860eb8eb
author Matei Pavaluca <matei.pavaluca@freescale.com> Mon Oct 27 10:42:44 2014 +0200
committer David S. Miller <davem@davemloft.net> Wed Oct 29 14:33:16 2014 -0400
tree 2be284741c04e285cc42a11b2a021c045bc44bd5
parent 43ef8d29eebb6f533f11439d48a927426c5a1918

gianfar: Implement PAUSE frame generation support

The hardware can automatically generate pause frames when the number
of free buffers drops under a certain threshold, but in order to do this,
the address of the last free buffer needs to be written to a specific
register for each RX queue.

This has to be done in 'gfar_clean_rx_ring' which is called for each
RX queue. In order not to impact performance, by adding a register write
for each incoming packet, this operation is done only when the PAUSE frame
transmission is enabled.

Whenever the link is readjusted, this capability is turned on or off.

Signed-off-by: Matei Pavaluca <matei.pavaluca@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/gianfar.c

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 329efca..86dccb26 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -173,10 +173,12 @@
 static int gfar_init_bds(struct net_device *ndev)
 {
 	struct gfar_private *priv = netdev_priv(ndev);
+	struct gfar __iomem *regs = priv->gfargrp[0].regs;
 	struct gfar_priv_tx_q *tx_queue = NULL;
 	struct gfar_priv_rx_q *rx_queue = NULL;
 	struct txbd8 *txbdp;
 	struct rxbd8 *rxbdp;
+	u32 *rfbptr;
 	int i, j;
 
 	for (i = 0; i < priv->num_tx_queues; i++) {
@@ -201,6 +203,7 @@
 		txbdp->status |= TXBD_WRAP;
 	}
 
+	rfbptr = &regs->rfbptr0;
 	for (i = 0; i < priv->num_rx_queues; i++) {
 		rx_queue = priv->rx_queue[i];
 		rx_queue->cur_rx = rx_queue->rx_bd_base;
@@ -227,6 +230,8 @@
 			rxbdp++;
 		}
 
+		rx_queue->rfbptr = rfbptr;
+		rfbptr += 2;
 	}
 
 	return 0;
@@ -336,6 +341,20 @@
 	}
 }
 
+static void gfar_init_rqprm(struct gfar_private *priv)
+{
+	struct gfar __iomem *regs = priv->gfargrp[0].regs;
+	u32 __iomem *baddr;
+	int i;
+
+	baddr = &regs->rqprm0;
+	for (i = 0; i < priv->num_rx_queues; i++) {
+		gfar_write(baddr, priv->rx_queue[i]->rx_ring_size |
+			   (DEFAULT_RX_LFC_THR << FBTHR_SHIFT));
+		baddr++;
+	}
+}
+
 static void gfar_rx_buff_size_config(struct gfar_private *priv)
 {
 	int frame_size = priv->ndev->mtu + ETH_HLEN + ETH_FCS_LEN;
@@ -396,6 +415,13 @@
 	if (priv->ndev->features & NETIF_F_HW_VLAN_CTAG_RX)
 		rctrl |= RCTRL_VLEX | RCTRL_PRSDEP_INIT;
 
+	/* Clear the LFC bit */
+	gfar_write(&regs->rctrl, rctrl);
+	/* Init flow control threshold values */
+	gfar_init_rqprm(priv);
+	gfar_write(&regs->ptv, DEFAULT_LFC_PTVVAL);
+	rctrl |= RCTRL_LFC;
+
 	/* Init rctrl based on our settings */
 	gfar_write(&regs->rctrl, rctrl);
 }
@@ -2859,6 +2885,10 @@
 		/* Setup the new bdp */
 		gfar_new_rxbdp(rx_queue, bdp, newskb);
 
+		/* Update Last Free RxBD pointer for LFC */
+		if (unlikely(rx_queue->rfbptr && priv->tx_actual_en))
+			gfar_write(rx_queue->rfbptr, (u32)bdp);
+
 		/* Update to the next pointer */
 		bdp = next_bd(bdp, base, rx_queue->rx_ring_size);
 
@@ -3393,6 +3423,9 @@
 {
 	struct gfar __iomem *regs = priv->gfargrp[0].regs;
 	struct phy_device *phydev = priv->phydev;
+	struct gfar_priv_rx_q *rx_queue = NULL;
+	int i;
+	struct rxbd8 *bdp;
 
 	if (unlikely(test_bit(GFAR_RESETTING, &priv->state)))
 		return;
@@ -3401,6 +3434,7 @@
 		u32 tempval1 = gfar_read(&regs->maccfg1);
 		u32 tempval = gfar_read(&regs->maccfg2);
 		u32 ecntrl = gfar_read(&regs->ecntrl);
+		u32 tx_flow_oldval = (tempval & MACCFG1_TX_FLOW);
 
 		if (phydev->duplex != priv->oldduplex) {
 			if (!(phydev->duplex))
@@ -3445,6 +3479,26 @@
 		tempval1 &= ~(MACCFG1_TX_FLOW | MACCFG1_RX_FLOW);
 		tempval1 |= gfar_get_flowctrl_cfg(priv);
 
+		/* Turn last free buffer recording on */
+		if ((tempval1 & MACCFG1_TX_FLOW) && !tx_flow_oldval) {
+			for (i = 0; i < priv->num_rx_queues; i++) {
+				rx_queue = priv->rx_queue[i];
+				bdp = rx_queue->cur_rx;
+				/* skip to previous bd */
+				bdp = skip_bd(bdp, rx_queue->rx_ring_size - 1,
+					      rx_queue->rx_bd_base,
+					      rx_queue->rx_ring_size);
+
+				if (rx_queue->rfbptr)
+					gfar_write(rx_queue->rfbptr, (u32)bdp);
+			}
+
+			priv->tx_actual_en = 1;
+		}
+
+		if (unlikely(!(tempval1 & MACCFG1_TX_FLOW) && tx_flow_oldval))
+			priv->tx_actual_en = 0;
+
 		gfar_write(&regs->maccfg1, tempval1);
 		gfar_write(&regs->maccfg2, tempval);
 		gfar_write(&regs->ecntrl, ecntrl);