netdev - [PATCH net-next-2.6 v9 01/20] pch_can: Add flow control processing

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Message-Id: <1292221467-8039-1-git-send-email-tomoya-linux@dsn.okisemi.com>
Date:	Mon, 13 Dec 2010 15:24:07 +0900
From:	Tomoya MORINAGA <tomoya-linux@....okisemi.com>
To:	wg@...ndegger.com, w.sang@...gutronix.de, chripell@...e.org,
	21cnbao@...il.com, sameo@...ux.intel.com,
	socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, davem@...emloft.net
Cc:	qi.wang@...el.com, yong.y.wang@...el.com,
	andrew.chih.howe.khor@...el.com, joel.clark@...el.com,
	kok.howg.ewe@...el.com, margie.foster@...el.com,
	Tomoya MORINAGA <tomoya-linux@....okisemi.com>
Subject: [PATCH net-next-2.6 v9 01/20] pch_can: Add flow control processing

Currently, there is no flow control processing.
Thus, Add flow control processing as
when there is no empty of tx buffer,
netif_stop_queue is called.
When there is empty buffer, netif_wake_queue is called.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@....okisemi.com>
---
 drivers/net/can/pch_can.c |   31 ++++++++++++-------------------
 1 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
index a9b6a65..f0f1404 100644
--- a/drivers/net/can/pch_can.c
+++ b/drivers/net/can/pch_can.c
@@ -102,6 +102,10 @@
 
 #define PCH_FIFO_THRESH		16
 
+/* TxRqst2 show status of MsgObjNo.17~32 */
+#define PCH_TREQ2_TX_MASK	(((1 << PCH_TX_OBJ_NUM) - 1) <<\
+							(PCH_RX_OBJ_END - 16))
+
 enum pch_ifreg {
 	PCH_RX_IFREG,
 	PCH_TX_IFREG,
@@ -871,6 +875,8 @@ MSG_OBJ:
 			dlc = 8;
 		stats->tx_bytes += dlc;
 		stats->tx_packets++;
+		if (int_stat == PCH_TX_OBJ_END)
+			netif_wake_queue(ndev);
 	}
 
 	int_stat = pch_can_int_pending(priv);
@@ -1009,18 +1015,6 @@ static int pch_close(struct net_device *ndev)
 	return 0;
 }
 
-static int pch_get_msg_obj_sts(struct net_device *ndev, u32 obj_id)
-{
-	u32 buffer_status = 0;
-	struct pch_can_priv *priv = netdev_priv(ndev);
-
-	/* Getting the message object status. */
-	buffer_status = (u32) pch_can_get_buffer_status(priv);
-
-	return buffer_status & obj_id;
-}
-
-
 static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
 {
 	int i, j;
@@ -1031,17 +1025,16 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
 	if (can_dropped_invalid_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
-	if (priv->tx_obj == PCH_TX_OBJ_END) { /* Point tail Obj */
-		while (pch_get_msg_obj_sts(ndev, (((1 << PCH_TX_OBJ_NUM)-1) <<
-					   PCH_RX_OBJ_NUM)))
-			udelay(500);
+	if (priv->tx_obj == PCH_TX_OBJ_END) {
+		if (ioread32(&priv->regs->treq2) & PCH_TREQ2_TX_MASK)
+			netif_stop_queue(ndev);
 
-		priv->tx_obj = PCH_TX_OBJ_START; /* Point head of Tx Obj ID */
-		tx_buffer_avail = priv->tx_obj; /* Point Tail of Tx Obj */
+		tx_buffer_avail = priv->tx_obj;
+		priv->tx_obj = PCH_TX_OBJ_START;
 	} else {
 		tx_buffer_avail = priv->tx_obj;
+		priv->tx_obj++;
 	}
-	priv->tx_obj++;
 
 	/* Reading the Msg Obj from the Msg RAM to the Interface register. */
 	iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[1].cmask);
-- 
1.6.0.6

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