net: ll_temac: Allow configuration of IRQ coalescing

This allows custom setup of IRQ coalescing for platforms using legacy
platform_device. The irq timeout and count parameters can be used for
tuning cpu load vs. latency.

I have maintained the 0x00000400 bit in TX_CHNL_CTRL.  It is specified as
unused in the documentation I have available.  It does not make any
difference in the hardware I have available, so it is left in to not risk
breaking other platforms where it might be used.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 32 insertions, 12 deletions

diff --git a/drivers/net/ethernet/xilinx/ll_temac.h b/drivers/net/ethernet/xilinx/ll_temac.h
index 990f9ed151b2..1aeda084b8f1 100644
--- a/drivers/net/ethernet/xilinx/ll_temac.h
+++ b/drivers/net/ethernet/xilinx/ll_temac.h
@@ -375,6 +375,10 @@ struct temac_local {
         int tx_bd_next;
         int tx_bd_tail;
         int rx_bd_ci;
+
+        /* DMA channel control setup */
+        u32 tx_chnl_ctrl;
+        u32 rx_chnl_ctrl;
 };
 
 /* Wrappers for temac_ior()/temac_iow() function pointers above */
diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index fec8e4c22944..bccef30bf64e 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -304,18 +304,15 @@ static int temac_dma_bd_init(struct net_device *ndev)
                 lp->rx_bd_v[i].app0 = cpu_to_be32(STS_CTRL_APP0_IRQONEND);
         }
 
-        lp->dma_out(lp, TX_CHNL_CTRL, 0x10220400 |
-                                          CHNL_CTRL_IRQ_EN |
-                                          CHNL_CTRL_IRQ_DLY_EN |
-                                          CHNL_CTRL_IRQ_COAL_EN);
-        /* 0x10220483 */
-        /* 0x00100483 */
-        lp->dma_out(lp, RX_CHNL_CTRL, 0xff070000 |
-                                          CHNL_CTRL_IRQ_EN |
-                                          CHNL_CTRL_IRQ_DLY_EN |
-                                          CHNL_CTRL_IRQ_COAL_EN |
-                                          CHNL_CTRL_IRQ_IOE);
-        /* 0xff010283 */
+        /* Configure DMA channel (irq setup) */
+        lp->dma_out(lp, TX_CHNL_CTRL, lp->tx_chnl_ctrl |
+                    0x00000400 | // Use 1 Bit Wide Counters. Currently Not Used!
+                    CHNL_CTRL_IRQ_EN | CHNL_CTRL_IRQ_ERR_EN |
+                    CHNL_CTRL_IRQ_DLY_EN | CHNL_CTRL_IRQ_COAL_EN);
+        lp->dma_out(lp, RX_CHNL_CTRL, lp->rx_chnl_ctrl |
+                    CHNL_CTRL_IRQ_IOE |
+                    CHNL_CTRL_IRQ_EN | CHNL_CTRL_IRQ_ERR_EN |
+                    CHNL_CTRL_IRQ_DLY_EN | CHNL_CTRL_IRQ_COAL_EN);
 
         lp->dma_out(lp, RX_CURDESC_PTR,  lp->rx_bd_p);
         lp->dma_out(lp, RX_TAILDESC_PTR,
@@ -1191,6 +1188,13 @@ static int temac_probe(struct platform_device *pdev)
                 lp->rx_irq = irq_of_parse_and_map(dma_np, 0);
                 lp->tx_irq = irq_of_parse_and_map(dma_np, 1);
 
+                /* Use defaults for IRQ delay/coalescing setup.  These
+                 * are configuration values, so does not belong in
+                 * device-tree.
+                 */
+                lp->tx_chnl_ctrl = 0x10220000;
+                lp->rx_chnl_ctrl = 0xff070000;
+
                 /* Finished with the DMA node; drop the reference */
                 of_node_put(dma_np);
         } else if (pdata) {
@@ -1214,6 +1218,18 @@ static int temac_probe(struct platform_device *pdev)
                 /* Get DMA RX and TX interrupts */
                 lp->rx_irq = platform_get_irq(pdev, 0);
                 lp->tx_irq = platform_get_irq(pdev, 1);
+
+                /* IRQ delay/coalescing setup */
+                if (pdata->tx_irq_timeout || pdata->tx_irq_count)
+                        lp->tx_chnl_ctrl = (pdata->tx_irq_timeout << 24) |
+                                (pdata->tx_irq_count << 16);
+                else
+                        lp->tx_chnl_ctrl = 0x10220000;
+                if (pdata->rx_irq_timeout || pdata->rx_irq_count)
+                        lp->rx_chnl_ctrl = (pdata->rx_irq_timeout << 24) |
+                                (pdata->rx_irq_count << 16);
+                else
+                        lp->rx_chnl_ctrl = 0xff070000;
         }
 
         /* Error handle returned DMA RX and TX interrupts */