On Fri, 6 Aug 2021 15:19:04 +0930 Joel Stanley wrote:
> LiteX is a soft system-on-chip that targets FPGAs. LiteETH is a basic
> network device that is commonly used in LiteX designs.
>
> The driver was first written in 2017 and has been maintained by the
> LiteX community in various trees. Thank you to all who have contributed.
> +config NET_VENDOR_LITEX
> + bool "LiteX devices"
> + default y
> + help
> + If you have a network (Ethernet) card belonging to this class, say Y.
> +
> + Note that the answer to this question doesn't directly affect the
> + kernel: saying N will just cause the configurator to skip all
> + the questions about LiteX devices. If you say Y, you will be asked
> + for your specific card in the following questions.
Maybe mention where the device is usually found (FPGAs) like you did in
the commit message, to help folks make a decision here?
> +config LITEX_LITEETH
> + tristate "LiteX Ethernet support"
> + help
> + If you wish to compile a kernel for hardware with a LiteX LiteEth
> + device then you should answer Y to this.
> +struct liteeth {
> + void __iomem *base;
> + void __iomem *mdio_base;
> + struct net_device *netdev;
> + struct device *dev;
> + struct mii_bus *mii_bus;
unused field
> +
> + /* Link management */
> + int cur_duplex;
> + int cur_speed;
> +
> + /* Tx */
> + int tx_slot;
> + int num_tx_slots;
> + void __iomem *tx_base;
> +
> + /* Rx */
> + int rx_slot;
> + int num_rx_slots;
> + void __iomem *rx_base;
> +};
> +
> +
> +static int liteeth_rx(struct net_device *netdev)
> +{
> + struct liteeth *priv = netdev_priv(netdev);
> + struct sk_buff *skb;
> + unsigned char *data;
> + u8 rx_slot;
> + int len;
> +
> + rx_slot = readb(priv->base + LITEETH_WRITER_SLOT);
> + len = readl(priv->base + LITEETH_WRITER_LENGTH);
> +
> + skb = netdev_alloc_skb(netdev, len + NET_IP_ALIGN);
netdev_alloc_skb_ip_align() ...
> + if (!skb) {
> + netdev_err(netdev, "couldn't get memory");
\n at the end? You can skip it but be consistent across messages
> + netdev->stats.rx_dropped++;
> + return NET_RX_DROP;
> + }
> +
> + /* Ensure alignemnt of the ip header within the skb */
> + skb_reserve(skb, NET_IP_ALIGN);
... then skip this
> + if (len == 0 || len > 2048)
> + return NET_RX_DROP;
Should this be counted somehow?
> + data = skb_put(skb, len);
> + memcpy_fromio(data, priv->rx_base + rx_slot * LITEETH_BUFFER_SIZE, len);
> + skb->protocol = eth_type_trans(skb, netdev);
> +
> + netdev->stats.rx_packets++;
> + netdev->stats.rx_bytes += len;
> +
> + return netif_rx(skb);
> +}
> +
> +static irqreturn_t liteeth_interrupt(int irq, void *dev_id)
> +{
> + struct net_device *netdev = dev_id;
> + struct liteeth *priv = netdev_priv(netdev);
> + u8 reg;
> +
> + reg = readb(priv->base + LITEETH_READER_EV_PENDING);
> + if (reg) {
> + netdev->stats.tx_packets++;
> + writeb(reg, priv->base + LITEETH_READER_EV_PENDING);
> + }
> +
> + reg = readb(priv->base + LITEETH_WRITER_EV_PENDING);
> + if (reg) {
> + liteeth_rx(netdev);
> + writeb(reg, priv->base + LITEETH_WRITER_EV_PENDING);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int liteeth_open(struct net_device *netdev)
> +{
> + struct liteeth *priv = netdev_priv(netdev);
> + int err;
> +
> + /* Clear pending events */
> + writeb(1, priv->base + LITEETH_WRITER_EV_PENDING);
> + writeb(1, priv->base + LITEETH_READER_EV_PENDING);
> +
> + err = request_irq(netdev->irq, liteeth_interrupt, 0, netdev->name, netdev);
> + if (err) {
> + netdev_err(netdev, "failed to request irq %d\n", netdev->irq);
> + return err;
> + }
> +
> + /* Enable IRQs */
> + writeb(1, priv->base + LITEETH_WRITER_EV_ENABLE);
> + writeb(1, priv->base + LITEETH_READER_EV_ENABLE);
> +
> + /* TODO: Remove these once we have working mdio support */
> + priv->cur_duplex = DUPLEX_FULL;
> + priv->cur_speed = SPEED_100;
please remove the fields until they're actually used
> + netif_carrier_on(netdev);
> +
> + netif_start_queue(netdev);
> +
> + return 0;
> +}
> +
> +static int liteeth_stop(struct net_device *netdev)
> +{
> + struct liteeth *priv = netdev_priv(netdev);
carrier_off() for symmetry?
> + netif_stop_queue(netdev);
> +
> + writeb(0, priv->base + LITEETH_WRITER_EV_ENABLE);
> + writeb(0, priv->base + LITEETH_READER_EV_ENABLE);
> +
> + free_irq(netdev->irq, netdev);
> + return 0;
> +}
> +
> +static int liteeth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
> +{
> + struct liteeth *priv = netdev_priv(netdev);
> + void __iomem *txbuffer;
> + int ret;
> + u8 val;
> +
> + /* Reject oversize packets */
> + if (unlikely(skb->len > MAX_PKT_SIZE)) {
> + if (net_ratelimit())
> + netdev_dbg(netdev, "tx packet too big\n");
> + goto drop;
> + }
> +
> + txbuffer = priv->tx_base + priv->tx_slot * LITEETH_BUFFER_SIZE;
> + memcpy_toio(txbuffer, skb->data, skb->len);
> + writeb(priv->tx_slot, priv->base + LITEETH_READER_SLOT);
> + writew(skb->len, priv->base + LITEETH_READER_LENGTH);
> +
> + ret = readl_poll_timeout_atomic(priv->base + LITEETH_READER_READY, val, val, 5, 1000);
Why the need for poll if there is an interrupt?
Why not stop the Tx queue once you're out of slots and restart
it when the completion interrupt comes?
> + if (ret == -ETIMEDOUT) {
> + netdev_err(netdev, "LITEETH_READER_READY timed out\n");
ratelimit this as well, please
> + goto drop;
> + }
> +
> + writeb(1, priv->base + LITEETH_READER_START);
> +
> + netdev->stats.tx_bytes += skb->len;
Please count bytes and packets in the same place
> + priv->tx_slot = (priv->tx_slot + 1) % priv->num_tx_slots;
> + dev_kfree_skb_any(skb);
> + return NETDEV_TX_OK;
> +drop:
> + /* Drop the packet */
> + dev_kfree_skb_any(skb);
> + netdev->stats.tx_dropped++;
> +
> + return NETDEV_TX_OK;
> +}
> +static int liteeth_probe(struct platform_device *pdev)
> +{
> + struct net_device *netdev;
> + void __iomem *buf_base;
> + struct resource *res;
> + struct liteeth *priv;
> + int irq, err;
> +
> + netdev = alloc_etherdev(sizeof(*priv));
> + if (!netdev)
> + return -ENOMEM;
> +
> + priv = netdev_priv(netdev);
> + priv->netdev = netdev;
> + priv->dev = &pdev->dev;
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0) {
> + dev_err(&pdev->dev, "Failed to get IRQ\n");
> + goto err;
`err` variable is not set here, you'd return 0
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + priv->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(priv->base)) {
> + err = PTR_ERR(priv->base);
> + goto err;
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + priv->mdio_base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(priv->mdio_base)) {
> + err = PTR_ERR(priv->mdio_base);
> + goto err;
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
> + buf_base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(buf_base)) {
> + err = PTR_ERR(buf_base);
> + goto err;
> + }
> +
> + err = of_property_read_u32(pdev->dev.of_node, "rx-fifo-depth",
> + &priv->num_rx_slots);
Please run checkpatch --strict and fix what it points out
> + if (err) {
> + dev_err(&pdev->dev, "unable to get rx-fifo-depth\n");
> + goto err;
> + }
> + return 0;
> +err:
> + free_netdev(netdev);
> + return err;
> +}
