[PATCH net-next V3 2/3] net: axienet: Preparatory changes for dmaengine support

From: Sarath Babu Naidu Gaddam
Date: Wed May 10 2023 - 04:51:18 EST

The axiethernet driver has in-built dma programming. The aim is to remove
axiethernet axidma programming after some time and instead use the
dmaengine framework to communicate with existing xilinx DMAengine
controller(xilinx_dma) driver.

Keep the axidma programming code under AXIENET_USE_DMA check so that
dmaengine changes can be added later.

Perform minor code reordering to minimize conditional
AXIENET_USE_DMA checks and there is no functional change.

It uses "dmas" property to identify whether it should use a dmaengine
framework or axiethernet axidma programming.

Signed-off-by: Sarath Babu Naidu Gaddam <sarath.babu.naidu.gaddam@xxxxxxx>
---
Changes in V3:
1) New Patch.
---
drivers/net/ethernet/xilinx/xilinx_axienet.h | 2 +
.../net/ethernet/xilinx/xilinx_axienet_main.c | 317 +++++++++++-------
2 files changed, 192 insertions(+), 127 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 575ff9de8985..10917d997d27 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -435,6 +435,7 @@ struct axidma_bd {
* @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
+ * @has_dmas: flag to check dmaengine framework usage.
*/
struct axienet_local {
struct net_device *ndev;
@@ -499,6 +500,7 @@ struct axienet_local {
u32 coalesce_usec_rx;
u32 coalesce_count_tx;
u32 coalesce_usec_tx;
+ u8 has_dmas;
};

/**
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 3e310b55bce2..8678fc09245a 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -54,6 +54,8 @@

#define AXIENET_REGS_N 40

+#define AXIENET_USE_DMA(lp) ((lp)->has_dmas)
+
/* Match table for of_platform binding */
static const struct of_device_id axienet_of_match[] = {
{ .compatible = "xlnx,axi-ethernet-1.00.a", },
@@ -588,10 +590,6 @@ static int axienet_device_reset(struct net_device *ndev)
struct axienet_local *lp = netdev_priv(ndev);
int ret;

- ret = __axienet_device_reset(lp);
- if (ret)
- return ret;
-
lp->max_frm_size = XAE_MAX_VLAN_FRAME_SIZE;
lp->options |= XAE_OPTION_VLAN;
lp->options &= (~XAE_OPTION_JUMBO);
@@ -605,11 +603,17 @@ static int axienet_device_reset(struct net_device *ndev)
lp->options |= XAE_OPTION_JUMBO;
}

- ret = axienet_dma_bd_init(ndev);
- if (ret) {
- netdev_err(ndev, "%s: descriptor allocation failed\n",
- __func__);
- return ret;
+ if (!AXIENET_USE_DMA(lp)) {
+ ret = __axienet_device_reset(lp);
+ if (ret)
+ return ret;
+
+ ret = axienet_dma_bd_init(ndev);
+ if (ret) {
+ netdev_err(ndev, "%s: descriptor allocation failed\n",
+ __func__);
+ return ret;
+ }
}

axienet_status = axienet_ior(lp, XAE_RCW1_OFFSET);
@@ -775,7 +779,7 @@ static int axienet_tx_poll(struct napi_struct *napi, int budget)
}

/**
- * axienet_start_xmit - Starts the transmission.
+ * axienet_start_xmit_legacy - Starts the transmission.
* @skb: sk_buff pointer that contains data to be Txed.
* @ndev: Pointer to net_device structure.
*
@@ -788,7 +792,7 @@ static int axienet_tx_poll(struct napi_struct *napi, int budget)
* it populates AXI Stream Control fields with appropriate values.
*/
static netdev_tx_t
-axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+axienet_start_xmit_legacy(struct sk_buff *skb, struct net_device *ndev)
{
u32 ii;
u32 num_frag;
@@ -890,6 +894,27 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
return NETDEV_TX_OK;
}

+/**
+ * axienet_start_xmit - Starts the transmission.
+ * @skb: sk_buff pointer that contains data to be Txed.
+ * @ndev: Pointer to net_device structure.
+ *
+ * Return: NETDEV_TX_OK, on success
+ * NETDEV_TX_BUSY, if any of the descriptors are not free
+ *
+ * This function is invoked from upper layers to initiate transmission
+ */
+static netdev_tx_t
+axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+{
+ struct axienet_local *lp = netdev_priv(ndev);
+
+ if (!AXIENET_USE_DMA(lp))
+ return axienet_start_xmit_legacy(skb, ndev);
+ else
+ return NETDEV_TX_BUSY;
+}
+
/**
* axienet_rx_poll - Triggered by RX ISR to complete the BD processing.
* @napi: Pointer to NAPI structure.
@@ -1124,41 +1149,22 @@ static irqreturn_t axienet_eth_irq(int irq, void *_ndev)
static void axienet_dma_err_handler(struct work_struct *work);

/**
- * axienet_open - Driver open routine.
- * @ndev: Pointer to net_device structure
+ * axienet_init_legacy_dma - init the dma legacy code.
+ * @ndev: Pointer to net_device structure
*
* Return: 0, on success.
- * non-zero error value on failure
+ * non-zero error value on failure
+ *
+ * This is the dma initialization code. It also allocates interrupt
+ * service routines, enables the interrupt lines and ISR handling.
*
- * This is the driver open routine. It calls phylink_start to start the
- * PHY device.
- * It also allocates interrupt service routines, enables the interrupt lines
- * and ISR handling. Axi Ethernet core is reset through Axi DMA core. Buffer
- * descriptors are initialized.
*/
-static int axienet_open(struct net_device *ndev)
+
+static inline int axienet_init_legacy_dma(struct net_device *ndev)
{
int ret;
struct axienet_local *lp = netdev_priv(ndev);

- dev_dbg(&ndev->dev, "axienet_open()\n");
-
- /* When we do an Axi Ethernet reset, it resets the complete core
- * including the MDIO. MDIO must be disabled before resetting.
- * Hold MDIO bus lock to avoid MDIO accesses during the reset.
- */
- axienet_lock_mii(lp);
- ret = axienet_device_reset(ndev);
- axienet_unlock_mii(lp);
-
- ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
- if (ret) {
- dev_err(lp->dev, "phylink_of_phy_connect() failed: %d\n", ret);
- return ret;
- }
-
- phylink_start(lp->phylink);
-
/* Enable worker thread for Axi DMA error handling */
INIT_WORK(&lp->dma_err_task, axienet_dma_err_handler);

@@ -1192,13 +1198,62 @@ static int axienet_open(struct net_device *ndev)
err_tx_irq:
napi_disable(&lp->napi_tx);
napi_disable(&lp->napi_rx);
- phylink_stop(lp->phylink);
- phylink_disconnect_phy(lp->phylink);
cancel_work_sync(&lp->dma_err_task);
dev_err(lp->dev, "request_irq() failed\n");
return ret;
}

+/**
+ * axienet_open - Driver open routine.
+ * @ndev: Pointer to net_device structure
+ *
+ * Return: 0, on success.
+ * non-zero error value on failure
+ *
+ * This is the driver open routine. It calls phylink_start to start the
+ * PHY device.
+ * It also allocates interrupt service routines, enables the interrupt lines
+ * and ISR handling. Axi Ethernet core is reset through Axi DMA core. Buffer
+ * descriptors are initialized.
+ */
+static int axienet_open(struct net_device *ndev)
+{
+ int ret;
+ struct axienet_local *lp = netdev_priv(ndev);
+
+ dev_dbg(&ndev->dev, "%s\n", __func__);
+
+ /* When we do an Axi Ethernet reset, it resets the complete core
+ * including the MDIO. MDIO must be disabled before resetting.
+ * Hold MDIO bus lock to avoid MDIO accesses during the reset.
+ */
+ axienet_lock_mii(lp);
+ ret = axienet_device_reset(ndev);
+ axienet_unlock_mii(lp);
+
+ ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
+ if (ret) {
+ dev_err(lp->dev, "phylink_of_phy_connect() failed: %d\n", ret);
+ return ret;
+ }
+
+ phylink_start(lp->phylink);
+
+ if (!AXIENET_USE_DMA(lp)) {
+ ret = axienet_init_legacy_dma(ndev);
+ if (ret)
+ goto error_code;
+ }
+
+ return 0;
+
+error_code:
+ phylink_stop(lp->phylink);
+ phylink_disconnect_phy(lp->phylink);
+
+ return ret;
+}
+
/**
* axienet_stop - Driver stop routine.
* @ndev: Pointer to net_device structure
@@ -1215,8 +1270,10 @@ static int axienet_stop(struct net_device *ndev)

dev_dbg(&ndev->dev, "axienet_close()\n");

- napi_disable(&lp->napi_tx);
- napi_disable(&lp->napi_rx);
+ if (!AXIENET_USE_DMA(lp)) {
+ napi_disable(&lp->napi_tx);
+ napi_disable(&lp->napi_rx);
+ }

phylink_stop(lp->phylink);
phylink_disconnect_phy(lp->phylink);
@@ -1224,18 +1281,18 @@ static int axienet_stop(struct net_device *ndev)
axienet_setoptions(ndev, lp->options &
~(XAE_OPTION_TXEN | XAE_OPTION_RXEN));

- axienet_dma_stop(lp);
+ if (!AXIENET_USE_DMA(lp)) {
+ axienet_dma_stop(lp);
+ cancel_work_sync(&lp->dma_err_task);
+ free_irq(lp->tx_irq, ndev);
+ free_irq(lp->rx_irq, ndev);
+ axienet_dma_bd_release(ndev);
+ }

axienet_iow(lp, XAE_IE_OFFSET, 0);

- cancel_work_sync(&lp->dma_err_task);
-
if (lp->eth_irq > 0)
free_irq(lp->eth_irq, ndev);
- free_irq(lp->tx_irq, ndev);
- free_irq(lp->rx_irq, ndev);
-
- axienet_dma_bd_release(ndev);
return 0;
}

@@ -1411,14 +1468,16 @@ static void axienet_ethtools_get_regs(struct net_device *ndev,
data[29] = axienet_ior(lp, XAE_FMI_OFFSET);
data[30] = axienet_ior(lp, XAE_AF0_OFFSET);
data[31] = axienet_ior(lp, XAE_AF1_OFFSET);
- data[32] = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
- data[33] = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
- data[34] = axienet_dma_in32(lp, XAXIDMA_TX_CDESC_OFFSET);
- data[35] = axienet_dma_in32(lp, XAXIDMA_TX_TDESC_OFFSET);
- data[36] = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
- data[37] = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
- data[38] = axienet_dma_in32(lp, XAXIDMA_RX_CDESC_OFFSET);
- data[39] = axienet_dma_in32(lp, XAXIDMA_RX_TDESC_OFFSET);
+ if (!AXIENET_USE_DMA(lp)) {
+ data[32] = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
+ data[33] = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
+ data[34] = axienet_dma_in32(lp, XAXIDMA_TX_CDESC_OFFSET);
+ data[35] = axienet_dma_in32(lp, XAXIDMA_TX_TDESC_OFFSET);
+ data[36] = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
+ data[37] = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
+ data[38] = axienet_dma_in32(lp, XAXIDMA_RX_CDESC_OFFSET);
+ data[39] = axienet_dma_in32(lp, XAXIDMA_RX_TDESC_OFFSET);
+ }
}

static void
@@ -1878,9 +1937,6 @@ static int axienet_probe(struct platform_device *pdev)
u64_stats_init(&lp->rx_stat_sync);
u64_stats_init(&lp->tx_stat_sync);

- netif_napi_add(ndev, &lp->napi_rx, axienet_rx_poll);
- netif_napi_add(ndev, &lp->napi_tx, axienet_tx_poll);
-
lp->axi_clk = devm_clk_get_optional(&pdev->dev, "s_axi_lite_clk");
if (!lp->axi_clk) {
/* For backward compatibility, if named AXI clock is not present,
@@ -2006,75 +2062,80 @@ static int axienet_probe(struct platform_device *pdev)
goto cleanup_clk;
}

- /* Find the DMA node, map the DMA registers, and decode the DMA IRQs */
- np = of_parse_phandle(pdev->dev.of_node, "axistream-connected", 0);
- if (np) {
- struct resource dmares;
+ if (!of_find_property(pdev->dev.of_node, "dmas", NULL)) {
+ /* Find the DMA node, map the DMA registers, and decode the DMA IRQs */
+ np = of_parse_phandle(pdev->dev.of_node, "axistream-connected", 0);

- ret = of_address_to_resource(np, 0, &dmares);
- if (ret) {
- dev_err(&pdev->dev,
- "unable to get DMA resource\n");
+ if (np) {
+ struct resource dmares;
+
+ ret = of_address_to_resource(np, 0, &dmares);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "unable to get DMA resource\n");
+ of_node_put(np);
+ goto cleanup_clk;
+ }
+ lp->dma_regs = devm_ioremap_resource(&pdev->dev,
+ &dmares);
+ lp->rx_irq = irq_of_parse_and_map(np, 1);
+ lp->tx_irq = irq_of_parse_and_map(np, 0);
of_node_put(np);
+ lp->eth_irq = platform_get_irq_optional(pdev, 0);
+ } else {
+ /* Check for these resources directly on the Ethernet node. */
+ lp->dma_regs = devm_platform_get_and_ioremap_resource(pdev, 1, NULL);
+ lp->rx_irq = platform_get_irq(pdev, 1);
+ lp->tx_irq = platform_get_irq(pdev, 0);
+ lp->eth_irq = platform_get_irq_optional(pdev, 2);
+ }
+ if (IS_ERR(lp->dma_regs)) {
+ dev_err(&pdev->dev, "could not map DMA regs\n");
+ ret = PTR_ERR(lp->dma_regs);
+ goto cleanup_clk;
+ }
+ if (lp->rx_irq <= 0 || lp->tx_irq <= 0) {
+ dev_err(&pdev->dev, "could not determine irqs\n");
+ ret = -ENOMEM;
goto cleanup_clk;
}
- lp->dma_regs = devm_ioremap_resource(&pdev->dev,
- &dmares);
- lp->rx_irq = irq_of_parse_and_map(np, 1);
- lp->tx_irq = irq_of_parse_and_map(np, 0);
- of_node_put(np);
- lp->eth_irq = platform_get_irq_optional(pdev, 0);
- } else {
- /* Check for these resources directly on the Ethernet node. */
- lp->dma_regs = devm_platform_get_and_ioremap_resource(pdev, 1, NULL);
- lp->rx_irq = platform_get_irq(pdev, 1);
- lp->tx_irq = platform_get_irq(pdev, 0);
- lp->eth_irq = platform_get_irq_optional(pdev, 2);
- }
- if (IS_ERR(lp->dma_regs)) {
- dev_err(&pdev->dev, "could not map DMA regs\n");
- ret = PTR_ERR(lp->dma_regs);
- goto cleanup_clk;
- }
- if ((lp->rx_irq <= 0) || (lp->tx_irq <= 0)) {
- dev_err(&pdev->dev, "could not determine irqs\n");
- ret = -ENOMEM;
- goto cleanup_clk;
- }

- /* Autodetect the need for 64-bit DMA pointers.
- * When the IP is configured for a bus width bigger than 32 bits,
- * writing the MSB registers is mandatory, even if they are all 0.
- * We can detect this case by writing all 1's to one such register
- * and see if that sticks: when the IP is configured for 32 bits
- * only, those registers are RES0.
- * Those MSB registers were introduced in IP v7.1, which we check first.
- */
- if ((axienet_ior(lp, XAE_ID_OFFSET) >> 24) >= 0x9) {
- void __iomem *desc = lp->dma_regs + XAXIDMA_TX_CDESC_OFFSET + 4;
-
- iowrite32(0x0, desc);
- if (ioread32(desc) == 0) { /* sanity check */
- iowrite32(0xffffffff, desc);
- if (ioread32(desc) > 0) {
- lp->features |= XAE_FEATURE_DMA_64BIT;
- addr_width = 64;
- dev_info(&pdev->dev,
- "autodetected 64-bit DMA range\n");
- }
+ /* Autodetect the need for 64-bit DMA pointers.
+ * When the IP is configured for a bus width bigger than 32 bits,
+ * writing the MSB registers is mandatory, even if they are all 0.
+ * We can detect this case by writing all 1's to one such register
+ * and see if that sticks: when the IP is configured for 32 bits
+ * only, those registers are RES0.
+ * Those MSB registers were introduced in IP v7.1, which we check first.
+ */
+ if ((axienet_ior(lp, XAE_ID_OFFSET) >> 24) >= 0x9) {
+ void __iomem *desc = lp->dma_regs + XAXIDMA_TX_CDESC_OFFSET + 4;
+
iowrite32(0x0, desc);
+ if (ioread32(desc) == 0) { /* sanity check */
+ iowrite32(0xffffffff, desc);
+ if (ioread32(desc) > 0) {
+ lp->features |= XAE_FEATURE_DMA_64BIT;
+ addr_width = 64;
+ dev_info(&pdev->dev,
+ "autodetected 64-bit DMA range\n");
+ }
+ iowrite32(0x0, desc);
+ }
+ }
+ if (!IS_ENABLED(CONFIG_64BIT) && lp->features & XAE_FEATURE_DMA_64BIT) {
+ dev_err(&pdev->dev, "64-bit addressable DMA is not compatible with 32-bit archecture\n");
+ ret = -EINVAL;
+ goto cleanup_clk;
}
- }
- if (!IS_ENABLED(CONFIG_64BIT) && lp->features & XAE_FEATURE_DMA_64BIT) {
- dev_err(&pdev->dev, "64-bit addressable DMA is not compatible with 32-bit archecture\n");
- ret = -EINVAL;
- goto cleanup_clk;
- }

- ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(addr_width));
- if (ret) {
- dev_err(&pdev->dev, "No suitable DMA available\n");
- goto cleanup_clk;
+ ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(addr_width));
+ if (ret) {
+ dev_err(&pdev->dev, "No suitable DMA available\n");
+ goto cleanup_clk;
+ }
+ netif_napi_add(ndev, &lp->napi_rx, axienet_rx_poll);
+ netif_napi_add(ndev, &lp->napi_tx, axienet_tx_poll);
}

/* Check for Ethernet core IRQ (optional) */
@@ -2092,14 +2153,16 @@ 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);
- if (ret)
- goto cleanup_clk;
+ if (!AXIENET_USE_DMA(lp)) {
+ lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
+ lp->coalesce_usec_tx = XAXIDMA_DFT_TX_USEC;
+ /* Reset core now that clocks are enabled, prior to accessing MDIO */
+ ret = __axienet_device_reset(lp);
+ if (ret)
+ goto cleanup_clk;
+ }

ret = axienet_mdio_setup(lp);
if (ret)
--
2.25.1