net: stmmac: Use interrupt mode INTM=1 for per channel irq

Enable per DMA channel interrupt that uses shared peripheral
interrupt (SPI), so only per channel TX and RX intr (TI/RI)
are handled by TX/RX ISR without calling common interrupt ISR.
Signed-off-by: Teoh Ji Sheng <ji.sheng.teoh@intel.com>
Signed-off-by: Swee Leong Ching <leong.ching.swee@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h

@@ -346,6 +346,9 @@
 /* DMA Registers */
 #define XGMAC_DMA_MODE			0x00003000
 #define XGMAC_SWR			BIT(0)
+#define XGMAC_DMA_MODE_INTM_MASK	GENMASK(13, 12)
+#define XGMAC_DMA_MODE_INTM_SHIFT	12
+#define XGMAC_DMA_MODE_INTM_MODE1	0x1
 #define XGMAC_DMA_SYSBUS_MODE		0x00003004
 #define XGMAC_WR_OSR_LMT		GENMASK(29, 24)
 #define XGMAC_WR_OSR_LMT_SHIFT		24

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c

@@ -31,6 +31,13 @@ static void dwxgmac2_dma_init(void __iomem *ioaddr,
 		value |= XGMAC_EAME;
 
 	writel(value, ioaddr + XGMAC_DMA_SYSBUS_MODE);
+
+	if (dma_cfg->multi_irq_en) {
+		value = readl(ioaddr + XGMAC_DMA_MODE);
+		value &= ~XGMAC_DMA_MODE_INTM_MASK;
+		value |= (XGMAC_DMA_MODE_INTM_MODE1 << XGMAC_DMA_MODE_INTM_SHIFT);
+		writel(value, ioaddr + XGMAC_DMA_MODE);
+	}
 }
 
 static void dwxgmac2_dma_init_chan(struct stmmac_priv *priv,
@@ -365,20 +372,19 @@ static int dwxgmac2_dma_interrupt(struct stmmac_priv *priv,
 	}
 
 	/* TX/RX NORMAL interrupts */
-	if (likely(intr_status & XGMAC_NIS)) {
 	if (likely(intr_status & XGMAC_RI)) {
 		u64_stats_update_begin(&rxq_stats->syncp);
 		rxq_stats->rx_normal_irq_n++;
 		u64_stats_update_end(&rxq_stats->syncp);
 		ret |= handle_rx;
 	}
+
 	if (likely(intr_status & (XGMAC_TI | XGMAC_TBU))) {
 		u64_stats_update_begin(&txq_stats->syncp);
 		txq_stats->tx_normal_irq_n++;
 		u64_stats_update_end(&txq_stats->syncp);
 		ret |= handle_tx;
 	}
-	}
 
 	/* Clear interrupts */
 	writel(intr_en & intr_status, ioaddr + XGMAC_DMA_CH_STATUS(chan));