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Subject[LINUX RFC PATCH] net: macb: Add support for partial store and forward
Date
From: Maulik Jodhani <maulik.jodhani@xilinx.com>

- Validate FCS in receive interrupt handler if Rx checksum offloading
is disabled
- Get rx-watermark value from DT

Signed-off-by: Maulik Jodhani <maulik.jodhani@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Pranavi Somisetty <pranavi.somisetty@amd.com>
---
drivers/net/ethernet/cadence/macb.h | 10 +++
drivers/net/ethernet/cadence/macb_main.c | 79 +++++++++++++++++++++++-
2 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 9c410f93a103..e4eebe8c8c46 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -82,6 +82,7 @@
#define GEM_NCFGR 0x0004 /* Network Config */
#define GEM_USRIO 0x000c /* User IO */
#define GEM_DMACFG 0x0010 /* DMA Configuration */
+#define GEM_PBUFRXCUT 0x0044 /* RX Partial Store and Forward */
#define GEM_JML 0x0048 /* Jumbo Max Length */
#define GEM_HS_MAC_CONFIG 0x0050 /* GEM high speed config */
#define GEM_HRB 0x0080 /* Hash Bottom */
@@ -342,6 +343,11 @@
#define GEM_ADDR64_OFFSET 30 /* Address bus width - 64b or 32b */
#define GEM_ADDR64_SIZE 1

+/* Bitfields in PBUFRXCUT */
+#define GEM_WTRMRK_OFFSET 0 /* Watermark value offset */
+#define GEM_WTRMRK_SIZE 12
+#define GEM_ENCUTTHRU_OFFSET 31 /* Enable RX partial store and forward */
+#define GEM_ENCUTTHRU_SIZE 1

/* Bitfields in NSR */
#define MACB_NSR_LINK_OFFSET 0 /* pcs_link_state */
@@ -720,6 +726,7 @@
#define MACB_CAPS_NEED_TSUCLK 0x00000400
#define MACB_CAPS_PCS 0x01000000
#define MACB_CAPS_HIGH_SPEED 0x02000000
+#define MACB_CAPS_PARTIAL_STORE_FORWARD 0x00000800
#define MACB_CAPS_CLK_HW_CHG 0x04000000
#define MACB_CAPS_MACB_IS_EMAC 0x08000000
#define MACB_CAPS_FIFO_MODE 0x10000000
@@ -1296,6 +1303,9 @@ struct macb {

u32 wol;

+ /* holds value of rx watermark value for pbuf_rxcutthru register */
+ u16 rx_watermark;
+
struct macb_ptp_info *ptp_info; /* macb-ptp interface */

struct phy *sgmii_phy; /* for ZynqMP SGMII mode */
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 95667b979fab..1f09fe1eec76 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -39,6 +39,7 @@
#include <linux/ptp_classify.h>
#include <linux/reset.h>
#include <linux/firmware/xlnx-zynqmp.h>
+#include <linux/crc32.h>
#include "macb.h"

/* This structure is only used for MACB on SiFive FU540 devices */
@@ -1314,6 +1315,15 @@ static void discard_partial_frame(struct macb_queue *queue, unsigned int begin,
*/
}

+static int macb_validate_hw_csum(struct sk_buff *skb)
+{
+ u32 pkt_csum = *((u32 *)&skb->data[skb->len - ETH_FCS_LEN]);
+ u32 csum = ~crc32_le(~0, skb_mac_header(skb),
+ skb->len + ETH_HLEN - ETH_FCS_LEN);
+
+ return (pkt_csum != csum);
+}
+
static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
int budget)
{
@@ -1375,6 +1385,16 @@ static int gem_rx(struct macb_queue *queue, struct napi_struct *napi,
bp->rx_buffer_size, DMA_FROM_DEVICE);

skb->protocol = eth_type_trans(skb, bp->dev);
+
+ /* Validate MAC fcs if RX checsum offload disabled */
+ if (!(bp->dev->features & NETIF_F_RXCSUM)) {
+ if (macb_validate_hw_csum(skb)) {
+ netdev_err(bp->dev, "incorrect FCS\n");
+ bp->dev->stats.rx_dropped++;
+ break;
+ }
+ }
+
skb_checksum_none_assert(skb);
if (bp->dev->features & NETIF_F_RXCSUM &&
!(bp->dev->flags & IFF_PROMISC) &&
@@ -1472,6 +1492,19 @@ static int macb_rx_frame(struct macb_queue *queue, struct napi_struct *napi,
break;
}

+ /* Validate MAC fcs if RX checsum offload disabled */
+ if (!(bp->dev->features & NETIF_F_RXCSUM)) {
+ if (macb_validate_hw_csum(skb)) {
+ netdev_err(bp->dev, "incorrect FCS\n");
+ bp->dev->stats.rx_dropped++;
+
+ /* Make descriptor updates visible to hardware */
+ wmb();
+
+ return 1;
+ }
+ }
+
/* Make descriptor updates visible to hardware */
wmb();

@@ -2567,6 +2600,10 @@ static void macb_reset_hw(struct macb *bp)
macb_writel(bp, TSR, -1);
macb_writel(bp, RSR, -1);

+ /* Disable RX partial store and forward and reset watermark value */
+ if (bp->caps & MACB_CAPS_PARTIAL_STORE_FORWARD)
+ gem_writel(bp, PBUFRXCUT, 0xFFF);
+
/* Disable all interrupts */
for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
queue_writel(queue, IDR, -1);
@@ -2700,7 +2737,11 @@ static void macb_init_hw(struct macb *bp)

config = macb_mdc_clk_div(bp);
config |= MACB_BF(RBOF, NET_IP_ALIGN); /* Make eth data aligned */
- config |= MACB_BIT(DRFCS); /* Discard Rx FCS */
+
+ /* Do not discard Rx FCS if RX checsum offload disabled */
+ if (bp->dev->features & NETIF_F_RXCSUM)
+ config |= MACB_BIT(DRFCS); /* Discard Rx FCS */
+
if (bp->caps & MACB_CAPS_JUMBO)
config |= MACB_BIT(JFRAME); /* Enable jumbo frames */
else
@@ -2720,6 +2761,15 @@ static void macb_init_hw(struct macb *bp)
bp->rx_frm_len_mask = MACB_RX_JFRMLEN_MASK;

macb_configure_dma(bp);
+
+ /* Enable RX partial store and forward and set watermark */
+ if (bp->caps & MACB_CAPS_PARTIAL_STORE_FORWARD) {
+ gem_writel(bp, PBUFRXCUT,
+ (gem_readl(bp, PBUFRXCUT) &
+ GEM_BF(WTRMRK, bp->rx_watermark)) |
+ GEM_BIT(ENCUTTHRU));
+ }
+
}

/* The hash address register is 64 bits long and takes up two
@@ -3812,10 +3862,29 @@ static void macb_configure_caps(struct macb *bp,
const struct macb_config *dt_conf)
{
u32 dcfg;
+ int retval;

if (dt_conf)
bp->caps = dt_conf->caps;

+ /* By default we set to partial store and forward mode for zynqmp.
+ * Disable if not set in devicetree.
+ */
+ if (bp->caps & MACB_CAPS_PARTIAL_STORE_FORWARD) {
+ retval = of_property_read_u16(bp->pdev->dev.of_node,
+ "rx-watermark",
+ &bp->rx_watermark);
+
+ /* Disable partial store and forward in case of error or
+ * invalid watermark value
+ */
+ if (retval || bp->rx_watermark > 0xFFF) {
+ dev_info(&bp->pdev->dev,
+ "Not enabling partial store and forward\n");
+ bp->caps &= ~MACB_CAPS_PARTIAL_STORE_FORWARD;
+ }
+ }
+
if (hw_is_gem(bp->regs, bp->native_io)) {
bp->caps |= MACB_CAPS_MACB_IS_GEM;

@@ -4072,6 +4141,8 @@ static int macb_init(struct platform_device *pdev)
/* Checksum offload is only available on gem with packet buffer */
if (macb_is_gem(bp) && !(bp->caps & MACB_CAPS_FIFO_MODE))
dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_RXCSUM;
+ if (bp->caps & MACB_CAPS_PARTIAL_STORE_FORWARD)
+ dev->hw_features &= ~NETIF_F_RXCSUM;
if (bp->caps & MACB_CAPS_SG_DISABLED)
dev->hw_features &= ~NETIF_F_SG;
dev->features = dev->hw_features;
@@ -4763,7 +4834,8 @@ static const struct macb_config np4_config = {
static const struct macb_config zynqmp_config = {
.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE |
MACB_CAPS_JUMBO |
- MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH,
+ MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH |
+ MACB_CAPS_PARTIAL_STORE_FORWARD,
.dma_burst_length = 16,
.clk_init = macb_clk_init,
.init = init_reset_optional,
@@ -4811,7 +4883,8 @@ static const struct macb_config sama7g5_emac_config = {

static const struct macb_config versal_config = {
.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE | MACB_CAPS_JUMBO |
- MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH | MACB_CAPS_NEED_TSUCLK,
+ MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH |
+ MACB_CAPS_NEED_TSUCLK | MACB_CAPS_PARTIAL_STORE_FORWARD,
.dma_burst_length = 16,
.clk_init = macb_clk_init,
.init = init_reset_optional,
--
2.36.1
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