net: axienet: add coalesce timer ethtool configuration

Add the ability to configure the RX/TX coalesce timer with ethtool.
Change default setting to scale with the clock rate rather than being a
fixed number of clock cycles.
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -119,11 +119,11 @@
 #define XAXIDMA_IRQ_ERROR_MASK		0x00004000 /* Error interrupt */
 #define XAXIDMA_IRQ_ALL_MASK		0x00007000 /* All interrupts */
 
-/* Default TX/RX Threshold and waitbound values for SGDMA mode */
+/* Default TX/RX Threshold and delay timer values for SGDMA mode */
 #define XAXIDMA_DFT_TX_THRESHOLD	24
-#define XAXIDMA_DFT_TX_WAITBOUND	254
+#define XAXIDMA_DFT_TX_USEC		50
 #define XAXIDMA_DFT_RX_THRESHOLD	1
-#define XAXIDMA_DFT_RX_WAITBOUND	254
+#define XAXIDMA_DFT_RX_USEC		50
 
 #define XAXIDMA_BD_CTRL_TXSOF_MASK	0x08000000 /* First tx packet */
 #define XAXIDMA_BD_CTRL_TXEOF_MASK	0x04000000 /* Last tx packet */
@@ -425,7 +425,9 @@ struct axidma_bd {
  * @csum_offload_on_tx_path:	Stores the checksum selection on TX side.
  * @csum_offload_on_rx_path:	Stores the checksum selection on RX side.
  * @coalesce_count_rx:	Store the irq coalesce on RX side.
+ * @coalesce_usec_rx:	IRQ coalesce delay for RX
  * @coalesce_count_tx:	Store the irq coalesce on TX side.
+ * @coalesce_usec_tx:	IRQ coalesce delay for TX
  */
 struct axienet_local {
 	struct net_device *ndev;
@@ -482,7 +484,9 @@ struct axienet_local {
 	int csum_offload_on_rx_path;
 
 	u32 coalesce_count_rx;
+	u32 coalesce_usec_rx;
 	u32 coalesce_count_tx;
+	u32 coalesce_usec_tx;
 };
 
 /**

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -33,7 +33,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/skbuff.h>
-#include <linux/spinlock.h>
+#include <linux/math64.h>
 #include <linux/phy.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
@@ -226,6 +226,28 @@ static void axienet_dma_bd_release(struct net_device *ndev)
 			  lp->rx_bd_p);
 }
 
+/**
+ * axienet_usec_to_timer - Calculate IRQ delay timer value
+ * @lp:		Pointer to the axienet_local structure
+ * @coalesce_usec: Microseconds to convert into timer value
+ */
+static u32 axienet_usec_to_timer(struct axienet_local *lp, u32 coalesce_usec)
+{
+	u32 result;
+	u64 clk_rate = 125000000; /* arbitrary guess if no clock rate set */
+
+	if (lp->axi_clk)
+		clk_rate = clk_get_rate(lp->axi_clk);
+
+	/* 1 Timeout Interval = 125 * (clock period of SG clock) */
+	result = DIV64_U64_ROUND_CLOSEST((u64)coalesce_usec * clk_rate,
+					 (u64)125000000);
+	if (result > 255)
+		result = 255;
+
+	return result;
+}
+
 /**
  * axienet_dma_start - Set up DMA registers and start DMA operation
  * @lp:		Pointer to the axienet_local structure
@@ -241,7 +263,8 @@ static void axienet_dma_start(struct axienet_local *lp)
 	 * the first RX packet. Otherwise leave at 0 to disable delay interrupt.
 	 */
 	if (lp->coalesce_count_rx > 1)
-		lp->rx_dma_cr |= (XAXIDMA_DFT_RX_WAITBOUND << XAXIDMA_DELAY_SHIFT) |
+		lp->rx_dma_cr |= (axienet_usec_to_timer(lp, lp->coalesce_usec_rx)
+					<< XAXIDMA_DELAY_SHIFT) |
 				 XAXIDMA_IRQ_DELAY_MASK;
 	axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET, lp->rx_dma_cr);
 
@@ -252,7 +275,8 @@ static void axienet_dma_start(struct axienet_local *lp)
 	 * the first TX packet. Otherwise leave at 0 to disable delay interrupt.
 	 */
 	if (lp->coalesce_count_tx > 1)
-		tx_cr |= (XAXIDMA_DFT_TX_WAITBOUND << XAXIDMA_DELAY_SHIFT) |
+		tx_cr |= (axienet_usec_to_timer(lp, lp->coalesce_usec_tx)
+				<< XAXIDMA_DELAY_SHIFT) |
 			 XAXIDMA_IRQ_DELAY_MASK;
 	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, tx_cr);
 
@@ -1469,14 +1493,12 @@ axienet_ethtools_get_coalesce(struct net_device *ndev,
 			      struct kernel_ethtool_coalesce *kernel_coal,
 			      struct netlink_ext_ack *extack)
 {
-	u32 regval = 0;
 	struct axienet_local *lp = netdev_priv(ndev);
-	regval = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	ecoalesce->rx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
-					     >> XAXIDMA_COALESCE_SHIFT;
-	regval = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	ecoalesce->tx_max_coalesced_frames = (regval & XAXIDMA_COALESCE_MASK)
-					     >> XAXIDMA_COALESCE_SHIFT;
+
+	ecoalesce->rx_max_coalesced_frames = lp->coalesce_count_rx;
+	ecoalesce->rx_coalesce_usecs = lp->coalesce_usec_rx;
+	ecoalesce->tx_max_coalesced_frames = lp->coalesce_count_tx;
+	ecoalesce->tx_coalesce_usecs = lp->coalesce_usec_tx;
 	return 0;
 }
 
@@ -1509,8 +1531,12 @@ axienet_ethtools_set_coalesce(struct net_device *ndev,
 
 	if (ecoalesce->rx_max_coalesced_frames)
 		lp->coalesce_count_rx = ecoalesce->rx_max_coalesced_frames;
+	if (ecoalesce->rx_coalesce_usecs)
+		lp->coalesce_usec_rx = ecoalesce->rx_coalesce_usecs;
 	if (ecoalesce->tx_max_coalesced_frames)
 		lp->coalesce_count_tx = ecoalesce->tx_max_coalesced_frames;
+	if (ecoalesce->tx_coalesce_usecs)
+		lp->coalesce_usec_tx = ecoalesce->tx_coalesce_usecs;
 
 	return 0;
 }
@@ -1541,7 +1567,8 @@ static int axienet_ethtools_nway_reset(struct net_device *dev)
 }
 
 static const struct ethtool_ops axienet_ethtool_ops = {
-	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
+	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
+				     ETHTOOL_COALESCE_USECS,
 	.get_drvinfo    = axienet_ethtools_get_drvinfo,
 	.get_regs_len   = axienet_ethtools_get_regs_len,
 	.get_regs       = axienet_ethtools_get_regs,
@@ -2028,7 +2055,9 @@ static int axienet_probe(struct platform_device *pdev)
 	}
 
 	lp->coalesce_count_rx = XAXIDMA_DFT_RX_THRESHOLD;
+	lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
 	lp->coalesce_count_tx = XAXIDMA_DFT_TX_THRESHOLD;
+	lp->coalesce_usec_tx = XAXIDMA_DFT_TX_USEC;
 
 	/* Reset core now that clocks are enabled, prior to accessing MDIO */
 	ret = __axienet_device_reset(lp);