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From:   Rafal Ozieblo <rafalo@cadence.com>
To:     Nicolas Ferre <nicolas.ferre@microchip.com>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     Rafal Ozieblo <rafalo@cadence.com>
Subject: [PATCH 3/3] net: macb: Receive Side Coalescing (RSC) feature added.
Date:   Sat, 14 Apr 2018 21:55:04 +0100
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This is basically the same as Large Receive Offload (LRO)
in Linux framework.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
 drivers/net/ethernet/cadence/macb.h      |  6 +++
 drivers/net/ethernet/cadence/macb_main.c | 70 +++++++++++++++++++++++++++++++-
 2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index a2cb805..9ebdde7 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -83,6 +83,7 @@
 #define GEM_USRIO		0x000c /* User IO */
 #define GEM_DMACFG		0x0010 /* DMA Configuration */
 #define GEM_JML			0x0048 /* Jumbo Max Length */
+#define GEM_RSC			0x0058 /* RSC Control */
 #define GEM_HRB			0x0080 /* Hash Bottom */
 #define GEM_HRT			0x0084 /* Hash Top */
 #define GEM_SA1B		0x0088 /* Specific1 Bottom */
@@ -318,6 +319,11 @@
 #define GEM_ADDR64_OFFSET	30 /* Address bus width - 64b or 32b */
 #define GEM_ADDR64_SIZE		1
 
+/* Bitfields in RSC control */
+#define GEM_RSCCTRL_OFFSET	1 /* RSC control */
+#define GEM_RSCCTRL_SIZE	15
+#define GEM_CLRMSK_OFFSET	16 /* RSC clear mask */
+#define GEM_CLRMSK_SIZE		1
 
 /* Bitfields in NSR */
 #define MACB_NSR_LINK_OFFSET	0 /* pcs_link_state */
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 27c406c..92bdcf1 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2377,6 +2377,8 @@ static int macb_open(struct net_device *dev)
 
 	if (!(bp->dev->hw_features & NETIF_F_LRO))
 		bufsz += NET_IP_ALIGN;
+	else
+		bufsz = 0xFF * 64; // For RSC Buffer Sizes must be set to 16K.
 
 	/* RX buffers initialization */
 	macb_init_rx_buffer_size(bp, bufsz);
@@ -2801,6 +2803,62 @@ static int macb_get_ts_info(struct net_device *netdev,
 	return ethtool_op_get_ts_info(netdev, info);
 }
 
+static void gem_enable_hdr_data_split(struct macb *bp, bool enable)
+{
+	u32 dmacfg;
+
+	dmacfg = gem_readl(bp, DMACFG);
+	if (enable)
+		dmacfg |= GEM_BIT(HDRS);
+	else
+		dmacfg &= ~GEM_BIT(HDRS);
+	gem_writel(bp, DMACFG, dmacfg);
+}
+
+static void gem_update_rsc_state(struct macb *bp, netdev_features_t feature)
+{
+	u32 rsc_control, rsc_control_new, queue, rsc;
+	bool enable, jumbo, any_enabled = false;
+	struct ethtool_rx_fs_item *item;
+	unsigned long flags;
+	u32 ncfgr;
+
+	enable = (!!(feature & NETIF_F_NTUPLE) && !!(feature & NETIF_F_LRO));
+	rsc = gem_readl(bp, RSC);
+	rsc_control = GEM_BFEXT(RSCCTRL, rsc);
+	rsc_control_new = 0;
+	if (enable) {
+		list_for_each_entry(item, &bp->rx_fs_list.list, list) {
+			queue = item->fs.ring_cookie;
+			rsc_control_new |= (1 << (queue - 1));
+			any_enabled = true;
+			netdev_dbg(bp->dev, "RSC %sabled for queue %u\n",
+				   enable ? "en" : "dis", queue);
+		}
+	}
+	if (rsc_control_new != rsc_control) {
+		rsc = GEM_BFINS(RSCCTRL, rsc_control_new, rsc);
+		gem_writel(bp, RSC, rsc);
+	}
+	if (bp->caps & MACB_CAPS_JUMBO) {
+		/* Don't enable jumbo mode for RSC:
+		 * disable unless not RSC and large MTU
+		 */
+		ncfgr = gem_readl(bp, NCFGR);
+		enable = !any_enabled;
+		jumbo = !!MACB_BFEXT(JFRAME, ncfgr);
+		/* and don't touch if already in the state we want */
+		if ((jumbo && !enable) || (!jumbo && enable)) {
+			ncfgr = MACB_BFINS(JFRAME, enable, ncfgr);
+			spin_lock_irqsave(&bp->lock, flags);
+			gem_writel(bp, NCFGR, ncfgr);
+			spin_unlock_irqrestore(&bp->lock, flags);
+		}
+	}
+	/* Need to enable header-data splitting also */
+	gem_enable_hdr_data_split(bp, any_enabled);
+}
+
 static void gem_enable_flow_filters(struct macb *bp, bool enable)
 {
 	struct ethtool_rx_fs_item *item;
@@ -2969,6 +3027,8 @@ static int gem_add_flow_filter(struct net_device *netdev,
 	if (netdev->features & NETIF_F_NTUPLE)
 		gem_enable_flow_filters(bp, 1);
 
+	/* enable RSC if LRO & NTUPLE on */
+	gem_update_rsc_state(bp, netdev->features);
 	spin_unlock_irqrestore(&bp->rx_fs_lock, flags);
 	return 0;
 
@@ -3009,6 +3069,7 @@ static int gem_del_flow_filter(struct net_device *netdev,
 			return 0;
 		}
 	}
+	gem_update_rsc_state(bp, netdev->features);
 
 	spin_unlock_irqrestore(&bp->rx_fs_lock, flags);
 	return -EINVAL;
@@ -3191,7 +3252,12 @@ static int macb_set_features(struct net_device *netdev,
 		bool turn_on = features & NETIF_F_NTUPLE;
 
 		gem_enable_flow_filters(bp, turn_on);
+		gem_update_rsc_state(bp, features);
 	}
+
+	/* LRO (Large Receive Offload) aka RSC (Receive Side Coalescing) */
+	if ((changed & NETIF_F_LRO) && macb_is_gem(bp))
+		gem_update_rsc_state(bp, features);
 	return 0;
 }
 
@@ -3449,8 +3515,10 @@ static int macb_init(struct platform_device *pdev)
 		dev->hw_features |= MACB_NETIF_LSO;
 
 	/* Check RSC capability */
-	if (GEM_BFEXT(PBUF_RSC, gem_readl(bp, DCFG6)))
+	if (GEM_BFEXT(PBUF_RSC, gem_readl(bp, DCFG6))) {
 		dev->hw_features |= NETIF_F_LRO;
+		gem_writel(bp, RSC, GEM_BIT(CLRMSK));
+	}
 
 	/* Checksum offload is only available on gem with packet buffer */
 	if (macb_is_gem(bp) && !(bp->caps & MACB_CAPS_FIFO_MODE))
-- 
2.4.5