stmmac: add CHAINED descriptor mode support (V4)

This patch enhances the STMMAC driver to support CHAINED mode of
descriptor.

STMMAC supports DMA descriptor to operate both in dual buffer(RING)
and linked-list(CHAINED) mode. In RING mode (default) each descriptor
points to two data buffer pointers whereas in CHAINED mode they point
to only one data buffer pointer.

In CHAINED mode each descriptor will have pointer to next descriptor in
the list, hence creating the explicit chaining in the descriptor itself,
whereas such explicit chaining is not possible in RING mode.

First version of this work has been done by Rayagond.
Then the patch has been reworked avoiding ifdef inside the C code.
A new header file has been added to define all the functions needed for
managing enhanced and normal descriptors.
In fact, these have to be specialized according to the ring/chain usage.
Two new C files have been also added to implement the helper routines
needed to manage: jumbo frames, chain and ring setup (i.e. desc3).

Signed-off-by: Rayagond Kokatanur <rayagond@vayavyalabs.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 52 insertions, 78 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index bf895cb75785..5eccd996cde0 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2,7 +2,7 @@
   This is the driver for the ST MAC 10/100/1000 on-chip Ethernet controllers.
   ST Ethernet IPs are built around a Synopsys IP Core.
 
-  Copyright (C) 2007-2009  STMicroelectronics Ltd
+	Copyright(C) 2007-2011 STMicroelectronics Ltd
 
   This program is free software; you can redistribute it and/or modify it
   under the terms and conditions of the GNU General Public License,
@@ -41,17 +41,16 @@
 #include <linux/if_ether.h>
 #include <linux/crc32.h>
 #include <linux/mii.h>
-#include <linux/phy.h>
 #include <linux/if.h>
 #include <linux/if_vlan.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/prefetch.h>
-#include "stmmac.h"
 #ifdef CONFIG_STMMAC_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 #endif
+#include "stmmac.h"
 
 #define STMMAC_RESOURCE_NAME	"stmmaceth"
 
@@ -388,11 +387,28 @@ static void display_ring(struct dma_desc *p, int size)
 	}
 }
 
+static int stmmac_set_bfsize(int mtu, int bufsize)
+{
+	int ret = bufsize;
+
+	if (mtu >= BUF_SIZE_4KiB)
+		ret = BUF_SIZE_8KiB;
+	else if (mtu >= BUF_SIZE_2KiB)
+		ret = BUF_SIZE_4KiB;
+	else if (mtu >= DMA_BUFFER_SIZE)
+		ret = BUF_SIZE_2KiB;
+	else
+		ret = DMA_BUFFER_SIZE;
+
+	return ret;
+}
+
 /**
  * init_dma_desc_rings - init the RX/TX descriptor rings
  * @dev: net device structure
  * Description:  this function initializes the DMA RX/TX descriptors
- * and allocates the socket buffers.
+ * and allocates the socket buffers. It suppors the chained and ring
+ * modes.
  */
 static void init_dma_desc_rings(struct net_device *dev)
 {
@@ -401,31 +417,24 @@ static void init_dma_desc_rings(struct net_device *dev)
 	struct sk_buff *skb;
 	unsigned int txsize = priv->dma_tx_size;
 	unsigned int rxsize = priv->dma_rx_size;
-	unsigned int bfsize = priv->dma_buf_sz;
-	int buff2_needed = 0, dis_ic = 0;
+	unsigned int bfsize;
+	int dis_ic = 0;
+	int des3_as_data_buf = 0;
 
-	/* Set the Buffer size according to the MTU;
-	 * indeed, in case of jumbo we need to bump-up the buffer sizes.
-	 */
-	if (unlikely(dev->mtu >= BUF_SIZE_8KiB))
-		bfsize = BUF_SIZE_16KiB;
-	else if (unlikely(dev->mtu >= BUF_SIZE_4KiB))
-		bfsize = BUF_SIZE_8KiB;
-	else if (unlikely(dev->mtu >= BUF_SIZE_2KiB))
-		bfsize = BUF_SIZE_4KiB;
-	else if (unlikely(dev->mtu >= DMA_BUFFER_SIZE))
-		bfsize = BUF_SIZE_2KiB;
+	/* Set the max buffer size according to the DESC mode
+	 * and the MTU. Note that RING mode allows 16KiB bsize. */
+	bfsize = priv->hw->ring->set_16kib_bfsize(dev->mtu);
+
+	if (bfsize == BUF_SIZE_16KiB)
+		des3_as_data_buf = 1;
 	else
-		bfsize = DMA_BUFFER_SIZE;
+		bfsize = stmmac_set_bfsize(dev->mtu, priv->dma_buf_sz);
 
 #ifdef CONFIG_STMMAC_TIMER
 	/* Disable interrupts on completion for the reception if timer is on */
 	if (likely(priv->tm->enable))
 		dis_ic = 1;
 #endif
-	/* If the MTU exceeds 8k so use the second buffer in the chain */
-	if (bfsize >= BUF_SIZE_8KiB)
-		buff2_needed = 1;
 
 	DBG(probe, INFO, "stmmac: txsize %d, rxsize %d, bfsize %d\n",
 	    txsize, rxsize, bfsize);
@@ -453,7 +462,7 @@ static void init_dma_desc_rings(struct net_device *dev)
 		return;
 	}
 
-	DBG(probe, INFO, "stmmac (%s) DMA desc rings: virt addr (Rx %p, "
+	DBG(probe, INFO, "stmmac (%s) DMA desc: virt addr (Rx %p, "
 	    "Tx %p)\n\tDMA phy addr (Rx 0x%08x, Tx 0x%08x)\n",
 	    dev->name, priv->dma_rx, priv->dma_tx,
 	    (unsigned int)priv->dma_rx_phy, (unsigned int)priv->dma_tx_phy);
@@ -475,8 +484,9 @@ static void init_dma_desc_rings(struct net_device *dev)
 						bfsize, DMA_FROM_DEVICE);
 
 		p->des2 = priv->rx_skbuff_dma[i];
-		if (unlikely(buff2_needed))
-			p->des3 = p->des2 + BUF_SIZE_8KiB;
+
+		priv->hw->ring->init_desc3(des3_as_data_buf, p);
+
 		DBG(probe, INFO, "[%p]\t[%p]\t[%x]\n", priv->rx_skbuff[i],
 			priv->rx_skbuff[i]->data, priv->rx_skbuff_dma[i]);
 	}
@@ -490,6 +500,12 @@ static void init_dma_desc_rings(struct net_device *dev)
 		priv->tx_skbuff[i] = NULL;
 		priv->dma_tx[i].des2 = 0;
 	}
+
+	/* In case of Chained mode this sets the des3 to the next
+	 * element in the chain */
+	priv->hw->ring->init_dma_chain(priv->dma_rx, priv->dma_rx_phy, rxsize);
+	priv->hw->ring->init_dma_chain(priv->dma_tx, priv->dma_tx_phy, txsize);
+
 	priv->dirty_tx = 0;
 	priv->cur_tx = 0;
 
@@ -620,8 +636,7 @@ static void stmmac_tx(struct stmmac_priv *priv)
 			dma_unmap_single(priv->device, p->des2,
 					 priv->hw->desc->get_tx_len(p),
 					 DMA_TO_DEVICE);
-		if (unlikely(p->des3))
-			p->des3 = 0;
+		priv->hw->ring->clean_desc3(p);
 
 		if (likely(skb != NULL)) {
 			/*
@@ -728,7 +743,6 @@ static void stmmac_no_timer_stopped(void)
  */
 static void stmmac_tx_err(struct stmmac_priv *priv)
 {
-
 	netif_stop_queue(priv->dev);
 
 	priv->hw->dma->stop_tx(priv->ioaddr);
@@ -1028,47 +1042,6 @@ static int stmmac_release(struct net_device *dev)
 	return 0;
 }
 
-static unsigned int stmmac_handle_jumbo_frames(struct sk_buff *skb,
-					       struct net_device *dev,
-					       int csum_insertion)
-{
-	struct stmmac_priv *priv = netdev_priv(dev);
-	unsigned int nopaged_len = skb_headlen(skb);
-	unsigned int txsize = priv->dma_tx_size;
-	unsigned int entry = priv->cur_tx % txsize;
-	struct dma_desc *desc = priv->dma_tx + entry;
-
-	if (nopaged_len > BUF_SIZE_8KiB) {
-
-		int buf2_size = nopaged_len - BUF_SIZE_8KiB;
-
-		desc->des2 = dma_map_single(priv->device, skb->data,
-					    BUF_SIZE_8KiB, DMA_TO_DEVICE);
-		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
-		priv->hw->desc->prepare_tx_desc(desc, 1, BUF_SIZE_8KiB,
-						csum_insertion);
-
-		entry = (++priv->cur_tx) % txsize;
-		desc = priv->dma_tx + entry;
-
-		desc->des2 = dma_map_single(priv->device,
-					skb->data + BUF_SIZE_8KiB,
-					buf2_size, DMA_TO_DEVICE);
-		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
-		priv->hw->desc->prepare_tx_desc(desc, 0, buf2_size,
-						csum_insertion);
-		priv->hw->desc->set_tx_owner(desc);
-		priv->tx_skbuff[entry] = NULL;
-	} else {
-		desc->des2 = dma_map_single(priv->device, skb->data,
-					nopaged_len, DMA_TO_DEVICE);
-		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
-		priv->hw->desc->prepare_tx_desc(desc, 1, nopaged_len,
-						csum_insertion);
-	}
-	return entry;
-}
-
 /**
  *  stmmac_xmit:
  *  @skb : the socket buffer
@@ -1083,6 +1056,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	int i, csum_insertion = 0;
 	int nfrags = skb_shinfo(skb)->nr_frags;
 	struct dma_desc *desc, *first;
+	unsigned int nopaged_len = skb_headlen(skb);
 
 	if (unlikely(stmmac_tx_avail(priv) < nfrags + 1)) {
 		if (!netif_queue_stopped(dev)) {
@@ -1103,7 +1077,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 		pr_info("stmmac xmit:\n"
 		       "\tskb addr %p - len: %d - nopaged_len: %d\n"
 		       "\tn_frags: %d - ip_summed: %d - %s gso\n",
-		       skb, skb->len, skb_headlen(skb), nfrags, skb->ip_summed,
+		       skb, skb->len, nopaged_len, nfrags, skb->ip_summed,
 		       !skb_is_gso(skb) ? "isn't" : "is");
 #endif
 
@@ -1116,14 +1090,14 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	if ((nfrags > 0) || (skb->len > ETH_FRAME_LEN))
 		pr_debug("stmmac xmit: skb len: %d, nopaged_len: %d,\n"
 		       "\t\tn_frags: %d, ip_summed: %d\n",
-		       skb->len, skb_headlen(skb), nfrags, skb->ip_summed);
+		       skb->len, nopaged_len, nfrags, skb->ip_summed);
 #endif
 	priv->tx_skbuff[entry] = skb;
-	if (unlikely(skb->len >= BUF_SIZE_4KiB)) {
-		entry = stmmac_handle_jumbo_frames(skb, dev, csum_insertion);
+
+	if (priv->hw->ring->is_jumbo_frm(skb->len, priv->plat->enh_desc)) {
+		entry = priv->hw->ring->jumbo_frm(priv, skb, csum_insertion);
 		desc = priv->dma_tx + entry;
 	} else {
-		unsigned int nopaged_len = skb_headlen(skb);
 		desc->des2 = dma_map_single(priv->device, skb->data,
 					nopaged_len, DMA_TO_DEVICE);
 		priv->hw->desc->prepare_tx_desc(desc, 1, nopaged_len,
@@ -1214,11 +1188,10 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv)
 					   DMA_FROM_DEVICE);
 
 			(p + entry)->des2 = priv->rx_skbuff_dma[entry];
-			if (unlikely(priv->plat->has_gmac)) {
-				if (bfsize >= BUF_SIZE_8KiB)
-					(p + entry)->des3 =
-					    (p + entry)->des2 + BUF_SIZE_8KiB;
-			}
+
+			if (unlikely(priv->plat->has_gmac))
+				priv->hw->ring->refill_desc3(bfsize, p + entry);
+
 			RX_DBG(KERN_INFO "\trefill entry #%d\n", entry);
 		}
 		wmb();
@@ -1795,6 +1768,7 @@ static int stmmac_mac_device_setup(struct net_device *dev)
 		device->desc = &ndesc_ops;
 
 	priv->hw = device;
+	priv->hw->ring = &ring_mode_ops;
 
 	if (device_can_wakeup(priv->device)) {
 		priv->wolopts = WAKE_MAGIC; /* Magic Frame as default */