Merge branch 'macb-partial-store-and-forward'

Pranavi Somisetty says:

====================
Add support for partial store and forward

Add support for partial store and forward mode in Cadence MACB.

Link for v1:
https://lore.kernel.org/all/20221213121245.13981-1-pranavi.somisetty@amd.com/

Changes v2:
1. Removed all the changes related to validating FCS when Rx checksum
offload is disabled.
2. Instead of using a platform dependent number (0xFFF) for the reset
value of rx watermark, derive it from designcfg_debug2 register.
3. Added a check to see if partial s/f is supported, by reading the
designcfg_debug6 register.
4. Added devicetree bindings for "rx-watermark" property.
Link for v2:
https://lore.kernel.org/all/20230511071214.18611-1-pranavi.somisetty@amd.com/

Changes v3:
1. Fixed DT schema error: "scalar properties shouldn't have array keywords"
2. Modified description of rx-watermark in to include units of the watermark value
3. Modified the DT property name corresponding to rx_watermark in pbuf_rxcutthru to
"cdns,rx-watermark".
4. Followed reverse christmas tree pattern in declaring variables.
5. Return -EINVAL when an invalid watermark value is set.
6. Removed netdev_info when partial store and forward is not enabled.
7. Validating the rx-watermark value in probe itself and only write to the register
in init.
8. Writing a reset value to the pbuf_cuthru register before disabing partial store
and forward is redundant. So removing it.
9. Removed the platform caps flag.
10. Instead of reading rx-watermark from DT in macb_configure_caps,
reading it in probe.
11. Changed Signed-Off-By and author names on the macb driver patch.
Link for v3:
https://lore.kernel.org/all/20230530095138.1302-1-pranavi.somisetty@amd.com/

Changes v4:
1. Modified description for "rx-watermark" property in the DT bindings.
2. Changed the width of the rx-watermark property to uint32.
3. Removed redundant code and unused variables.
4. When the rx-watermark value is invalid, instead of returning EINVAL,
do not enable partial store and forward.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/cdns,macb.yaml

@@ -109,6 +109,16 @@ properties:
   power-domains:
     maxItems: 1
 
+  cdns,rx-watermark:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      When the receive partial store and forward mode is activated,
+      the receiver will only begin to forward the packet to the external
+      AHB or AXI slave when enough packet data is stored in the SRAM packet buffer.
+      rx-watermark corresponds to the number of SRAM buffer locations,
+      that need to be filled, before the forwarding process is activated.
+      Width of the SRAM is platform dependent, and can be 4, 8 or 16 bytes.
+
   '#address-cells':
     const: 1
 
@@ -166,6 +176,7 @@ examples:
             compatible = "cdns,macb";
             reg = <0xfffc4000 0x4000>;
             interrupts = <21>;
+            cdns,rx-watermark = <0x44>;
             phy-mode = "rmii";
             local-mac-address = [3a 0e 03 04 05 06];
             clock-names = "pclk", "hclk", "tx_clk";

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 */
@@ -347,6 +348,10 @@
 #define GEM_ADDR64_SIZE		1
 
 
+/* Bitfields in PBUFRXCUT */
+#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 */
 #define MACB_NSR_LINK_SIZE	1
@@ -513,6 +518,8 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+#define GEM_RX_PBUF_ADDR_OFFSET			22
+#define GEM_RX_PBUF_ADDR_SIZE			4
 
 /* Bitfields in DCFG5. */
 #define GEM_TSU_OFFSET				8
@@ -521,6 +528,8 @@
 /* Bitfields in DCFG6. */
 #define GEM_PBUF_LSO_OFFSET			27
 #define GEM_PBUF_LSO_SIZE			1
+#define GEM_PBUF_CUTTHRU_OFFSET			25
+#define GEM_PBUF_CUTTHRU_SIZE			1
 #define GEM_DAW64_OFFSET			23
 #define GEM_DAW64_SIZE				1
 
@@ -1290,6 +1299,9 @@ struct macb {
 
 	u32			wol;
 
+	/* holds value of rx watermark value for pbuf_rxcutthru register */
+	u32			rx_watermark;
+
 	struct macb_ptp_info	*ptp_info;	/* macb-ptp interface */
 
 	struct phy		*sgmii_phy;	/* for ZynqMP SGMII mode */

drivers/net/ethernet/cadence/macb_main.c

@@ -2635,6 +2635,9 @@ 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 */
+	gem_writel(bp, PBUFRXCUT, 0);
+
 	/* Disable all interrupts */
 	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
 		queue_writel(queue, IDR, -1);
@@ -2792,6 +2795,10 @@ 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->rx_watermark)
+		gem_writel(bp, PBUFRXCUT, (bp->rx_watermark | GEM_BIT(ENCUTTHRU)));
 }
 
 /* The hash address register is 64 bits long and takes up two
@@ -4946,6 +4953,7 @@ static int macb_probe(struct platform_device *pdev)
 	phy_interface_t interface;
 	struct net_device *dev;
 	struct resource *regs;
+	u32 wtrmrk_rst_val;
 	void __iomem *mem;
 	struct macb *bp;
 	int err, val;
@@ -5025,6 +5033,25 @@ static int macb_probe(struct platform_device *pdev)
 
 	bp->usrio = macb_config->usrio;
 
+	/* By default we set to partial store and forward mode for zynqmp.
+	 * Disable if not set in devicetree.
+	 */
+	if (GEM_BFEXT(PBUF_CUTTHRU, gem_readl(bp, DCFG6))) {
+		err = of_property_read_u32(bp->pdev->dev.of_node,
+					   "cdns,rx-watermark",
+					   &bp->rx_watermark);
+
+		if (!err) {
+			/* Disable partial store and forward in case of error or
+			 * invalid watermark value
+			 */
+			wtrmrk_rst_val = (1 << (GEM_BFEXT(RX_PBUF_ADDR, gem_readl(bp, DCFG2)))) - 1;
+			if (bp->rx_watermark > wtrmrk_rst_val || !bp->rx_watermark) {
+				dev_info(&bp->pdev->dev, "Invalid watermark value\n");
+				bp->rx_watermark = 0;
+			}
+		}
+	}
 	spin_lock_init(&bp->lock);
 
 	/* setup capabilities */