amd-xgbe: Add support for new DMA interrupt mode

The current per channel DMA interrupt support is based on an edge
triggered interrupt that is not maskable. This results in having to call
the disable_irq/enable_irq functions in order to prevent interrupts
during napi processing. The hardware now has a way to configure the per
channel DMA interrupt that will allow for masking the interrupt which
prevents calling disable_irq/enable_irq now. This patch makes use of
this support.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amd/xgbe/xgbe-common.h

@@ -159,6 +159,8 @@
 #define DMA_ISR_MACIS_WIDTH		1
 #define DMA_ISR_MTLIS_INDEX		16
 #define DMA_ISR_MTLIS_WIDTH		1
+#define DMA_MR_INTM_INDEX		12
+#define DMA_MR_INTM_WIDTH		2
 #define DMA_MR_SWR_INDEX		0
 #define DMA_MR_SWR_WIDTH		1
 #define DMA_SBMR_EAME_INDEX		11

drivers/net/ethernet/amd/xgbe/xgbe-dev.c

@@ -646,6 +646,11 @@ static void xgbe_enable_dma_interrupts(struct xgbe_prv_data *pdata)
 	unsigned int dma_ch_isr, dma_ch_ier;
 	unsigned int i;
 
+	/* Set the interrupt mode if supported */
+	if (pdata->channel_irq_mode)
+		XGMAC_IOWRITE_BITS(pdata, DMA_MR, INTM,
+				   pdata->channel_irq_mode);
+
 	channel = pdata->channel;
 	for (i = 0; i < pdata->channel_count; i++, channel++) {
 		/* Clear all the interrupts which are set */
@@ -667,19 +672,21 @@ static void xgbe_enable_dma_interrupts(struct xgbe_prv_data *pdata)
 		if (channel->tx_ring) {
 			/* Enable the following Tx interrupts
 			 *   TIE  - Transmit Interrupt Enable (unless using
-			 *          per channel interrupts)
+			 *          per channel interrupts in edge triggered
+			 *          mode)
 			 */
-			if (!pdata->per_channel_irq)
+			if (!pdata->per_channel_irq || pdata->channel_irq_mode)
 				XGMAC_SET_BITS(dma_ch_ier, DMA_CH_IER, TIE, 1);
 		}
 		if (channel->rx_ring) {
 			/* Enable following Rx interrupts
 			 *   RBUE - Receive Buffer Unavailable Enable
 			 *   RIE  - Receive Interrupt Enable (unless using
-			 *          per channel interrupts)
+			 *          per channel interrupts in edge triggered
+			 *          mode)
 			 */
 			XGMAC_SET_BITS(dma_ch_ier, DMA_CH_IER, RBUE, 1);
-			if (!pdata->per_channel_irq)
+			if (!pdata->per_channel_irq || pdata->channel_irq_mode)
 				XGMAC_SET_BITS(dma_ch_ier, DMA_CH_IER, RIE, 1);
 		}
 

drivers/net/ethernet/amd/xgbe/xgbe-drv.c

@@ -252,48 +252,60 @@ static int xgbe_calc_rx_buf_size(struct net_device *netdev, unsigned int mtu)
 	return rx_buf_size;
 }
 
-static void xgbe_enable_rx_tx_ints(struct xgbe_prv_data *pdata)
+static void xgbe_enable_rx_tx_int(struct xgbe_prv_data *pdata,
+				  struct xgbe_channel *channel)
 {
 	struct xgbe_hw_if *hw_if = &pdata->hw_if;
-	struct xgbe_channel *channel;
 	enum xgbe_int int_id;
+
+	if (channel->tx_ring && channel->rx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
+	else if (channel->tx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_TI;
+	else if (channel->rx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_RI;
+	else
+		return;
+
+	hw_if->enable_int(channel, int_id);
+}
+
+static void xgbe_enable_rx_tx_ints(struct xgbe_prv_data *pdata)
+{
+	struct xgbe_channel *channel;
 	unsigned int i;
 
 	channel = pdata->channel;
-	for (i = 0; i < pdata->channel_count; i++, channel++) {
-		if (channel->tx_ring && channel->rx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
-		else if (channel->tx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_TI;
-		else if (channel->rx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_RI;
-		else
-			continue;
+	for (i = 0; i < pdata->channel_count; i++, channel++)
+		xgbe_enable_rx_tx_int(pdata, channel);
+}
 
-		hw_if->enable_int(channel, int_id);
-	}
+static void xgbe_disable_rx_tx_int(struct xgbe_prv_data *pdata,
+				   struct xgbe_channel *channel)
+{
+	struct xgbe_hw_if *hw_if = &pdata->hw_if;
+	enum xgbe_int int_id;
+
+	if (channel->tx_ring && channel->rx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
+	else if (channel->tx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_TI;
+	else if (channel->rx_ring)
+		int_id = XGMAC_INT_DMA_CH_SR_RI;
+	else
+		return;
+
+	hw_if->disable_int(channel, int_id);
 }
 
 static void xgbe_disable_rx_tx_ints(struct xgbe_prv_data *pdata)
 {
-	struct xgbe_hw_if *hw_if = &pdata->hw_if;
 	struct xgbe_channel *channel;
-	enum xgbe_int int_id;
 	unsigned int i;
 
 	channel = pdata->channel;
-	for (i = 0; i < pdata->channel_count; i++, channel++) {
-		if (channel->tx_ring && channel->rx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
-		else if (channel->tx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_TI;
-		else if (channel->rx_ring)
-			int_id = XGMAC_INT_DMA_CH_SR_RI;
-		else
-			continue;
-
-		hw_if->disable_int(channel, int_id);
-	}
+	for (i = 0; i < pdata->channel_count; i++, channel++)
+		xgbe_disable_rx_tx_int(pdata, channel);
 }
 
 static irqreturn_t xgbe_isr(int irq, void *data)
@@ -339,6 +351,13 @@ static irqreturn_t xgbe_isr(int irq, void *data)
 				/* Turn on polling */
 				__napi_schedule_irqoff(&pdata->napi);
 			}
+		} else {
+			/* Don't clear Rx/Tx status if doing per channel DMA
+			 * interrupts, these will be cleared by the ISR for
+			 * per channel DMA interrupts.
+			 */
+			XGMAC_SET_BITS(dma_ch_isr, DMA_CH_SR, TI, 0);
+			XGMAC_SET_BITS(dma_ch_isr, DMA_CH_SR, RI, 0);
 		}
 
 		if (XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, RBU))
@@ -348,7 +367,7 @@ static irqreturn_t xgbe_isr(int irq, void *data)
 		if (XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, FBE))
 			schedule_work(&pdata->restart_work);
 
-		/* Clear all interrupt signals */
+		/* Clear interrupt signals */
 		XGMAC_DMA_IOWRITE(channel, DMA_CH_SR, dma_ch_isr);
 	}
 
@@ -385,18 +404,29 @@ isr_done:
 static irqreturn_t xgbe_dma_isr(int irq, void *data)
 {
 	struct xgbe_channel *channel = data;
+	struct xgbe_prv_data *pdata = channel->pdata;
+	unsigned int dma_status;
 
 	/* Per channel DMA interrupts are enabled, so we use the per
 	 * channel napi structure and not the private data napi structure
 	 */
 	if (napi_schedule_prep(&channel->napi)) {
 		/* Disable Tx and Rx interrupts */
-		disable_irq_nosync(channel->dma_irq);
+		if (pdata->channel_irq_mode)
+			xgbe_disable_rx_tx_int(pdata, channel);
+		else
+			disable_irq_nosync(channel->dma_irq);
 
 		/* Turn on polling */
 		__napi_schedule_irqoff(&channel->napi);
 	}
 
+	/* Clear Tx/Rx signals */
+	dma_status = 0;
+	XGMAC_SET_BITS(dma_status, DMA_CH_SR, TI, 1);
+	XGMAC_SET_BITS(dma_status, DMA_CH_SR, RI, 1);
+	XGMAC_DMA_IOWRITE(channel, DMA_CH_SR, dma_status);
+
 	return IRQ_HANDLED;
 }
 
@@ -413,7 +443,10 @@ static void xgbe_tx_timer(unsigned long data)
 	if (napi_schedule_prep(napi)) {
 		/* Disable Tx and Rx interrupts */
 		if (pdata->per_channel_irq)
-			disable_irq_nosync(channel->dma_irq);
+			if (pdata->channel_irq_mode)
+				xgbe_disable_rx_tx_int(pdata, channel);
+			else
+				disable_irq_nosync(channel->dma_irq);
 		else
 			xgbe_disable_rx_tx_ints(pdata);
 
@@ -2030,6 +2063,7 @@ static int xgbe_one_poll(struct napi_struct *napi, int budget)
 {
 	struct xgbe_channel *channel = container_of(napi, struct xgbe_channel,
 						    napi);
+	struct xgbe_prv_data *pdata = channel->pdata;
 	int processed = 0;
 
 	DBGPR("-->xgbe_one_poll: budget=%d\n", budget);
@@ -2046,7 +2080,10 @@ static int xgbe_one_poll(struct napi_struct *napi, int budget)
 		napi_complete_done(napi, processed);
 
 		/* Enable Tx and Rx interrupts */
-		enable_irq(channel->dma_irq);
+		if (pdata->channel_irq_mode)
+			xgbe_enable_rx_tx_int(pdata, channel);
+		else
+			enable_irq(channel->dma_irq);
 	}
 
 	DBGPR("<--xgbe_one_poll: received = %d\n", processed);

drivers/net/ethernet/amd/xgbe/xgbe-pci.c

@@ -163,6 +163,7 @@ static int xgbe_config_msi(struct xgbe_prv_data *pdata)
 		pdata->channel_irq_count = j;
 
 		pdata->per_channel_irq = 1;
+		pdata->channel_irq_mode = XGBE_IRQ_MODE_LEVEL;
 	} else {
 		pdata->ecc_irq = pdata->pcidev->irq;
 		pdata->i2c_irq = pdata->pcidev->irq;
@@ -215,6 +216,7 @@ static int xgbe_config_msix(struct xgbe_prv_data *pdata)
 	pdata->channel_irq_count = j;
 
 	pdata->per_channel_irq = 1;
+	pdata->channel_irq_mode = XGBE_IRQ_MODE_LEVEL;
 
 	if (netif_msg_probe(pdata))
 		dev_dbg(pdata->dev, "MSI-X interrupts enabled\n");

drivers/net/ethernet/amd/xgbe/xgbe-platform.c

@@ -426,8 +426,10 @@ static int xgbe_platform_probe(struct platform_device *pdev)
 	pdata->phy_mode = PHY_INTERFACE_MODE_XGMII;
 
 	/* Check for per channel interrupt support */
-	if (device_property_present(dev, XGBE_DMA_IRQS_PROPERTY))
+	if (device_property_present(dev, XGBE_DMA_IRQS_PROPERTY)) {
 		pdata->per_channel_irq = 1;
+		pdata->channel_irq_mode = XGBE_IRQ_MODE_EDGE;
+	}
 
 	/* Obtain device settings unique to ACPI/OF */
 	if (pdata->use_acpi)

drivers/net/ethernet/amd/xgbe/xgbe.h

@@ -171,6 +171,10 @@
 #define XGBE_DMA_SYS_ARCACHE	0x0
 #define XGBE_DMA_SYS_AWCACHE	0x0
 
+/* DMA channel interrupt modes */
+#define XGBE_IRQ_MODE_EDGE	0
+#define XGBE_IRQ_MODE_LEVEL	1
+
 #define XGBE_DMA_INTERRUPT_MASK	0x31c7
 
 #define XGMAC_MIN_PACKET	60
@@ -874,6 +878,7 @@ struct xgbe_prv_data {
 	unsigned int irq_shared;
 	unsigned int irq_count;
 	unsigned int channel_irq_count;
+	unsigned int channel_irq_mode;
 
 	struct xgbe_hw_if hw_if;
 	struct xgbe_phy_if phy_if;