Date:   Thu, 1 Aug 2019 13:25:20 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Avi Fishman <avifishman70@...il.com>
Cc:     Patrick Venture <venture@...gle.com>,
        Nancy Yuen <yuenn@...gle.com>, benjaminfair@...gle.com,
        David Miller <davem@...emloft.net>, robh+dt@...nel.org,
        mark.rutland@....com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        tmaimon77@...il.com, tali.perry1@...il.com,
        openbmc@...ts.ozlabs.org,
        Network Development <netdev@...r.kernel.org>,
        devicetree@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>, tglx@...utronix.de
Subject: Re: [PATCH v1 2/2] net: npcm: add NPCM7xx EMC 10/100 Ethernet driver

On Thu, Aug 1, 2019 at 3:28 AM Avi Fishman <avifishman70@...il.com> wrote:
>
> EMC Ethernet Media Access Controller supports 10/100 Mbps and
> RMII.
> This driver has been working on Nuvoton BMC NPCM7xx.
>
> Signed-off-by: Avi Fishman <avifishman70@...il.com>



> +/* global setting for driver */
> +#define RX_QUEUE_LEN   128
> +#define TX_QUEUE_LEN   64
> +#define MAX_RBUFF_SZ   0x600
> +#define MAX_TBUFF_SZ   0x600
> +#define TX_TIMEOUT     50
> +#define DELAY          1000
> +#define CAM0           0x0
> +#define RX_POLL_SIZE    16
> +
> +#ifdef CONFIG_VLAN_8021Q
> +#define IS_VLAN 1
> +#else
> +#define IS_VLAN 0
> +#endif
> +
> +#define MAX_PACKET_SIZE           (1514 + (IS_VLAN * 4))

1514 -> ETH_FRAME_LEN

4 -> VLAN_HLEN

Does this device support stacked VLAN?

Is this really the device maximum?

> +#define MAX_PACKET_SIZE_W_CRC     (MAX_PACKET_SIZE + 4) /* 1518 */

4 -> ETH_FCS_LEN

> +#if defined CONFIG_NPCM7XX_EMC_ETH_DEBUG || defined CONFIG_DEBUG_FS
> +#define REG_PRINT(reg_name) {t = scnprintf(next, size, "%-10s = %08X\n", \
> +       #reg_name, readl(ether->reg + (reg_name))); size -= t;  next += t; }
> +#define DUMP_PRINT(f, x...) {t = scnprintf(next, size, f, ## x); size -= t; \
> +       next += t; }
> +
> +static int npcm7xx_info_dump(char *buf, int count, struct net_device *netdev)
> +{
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +       struct npcm7xx_txbd *txbd;
> +       struct npcm7xx_rxbd *rxbd;
> +       unsigned long flags;
> +       unsigned int i, cur, txd_offset, rxd_offset;
> +       char *next = buf;
> +       unsigned int size = count;
> +       int t;
> +       int is_locked = spin_is_locked(&ether->lock);
> +
> +       if (!is_locked)
> +               spin_lock_irqsave(&ether->lock, flags);
> +
> +       /* ------basic driver information ---- */
> +       DUMP_PRINT("NPCM7XX EMC %s driver version: %s\n", netdev->name,
> +                  DRV_MODULE_VERSION);
> +
> +       REG_PRINT(REG_CAMCMR);
> +       REG_PRINT(REG_CAMEN);
> +       REG_PRINT(REG_CAMM_BASE);
> +       REG_PRINT(REG_CAML_BASE);
> +       REG_PRINT(REG_TXDLSA);
> +       REG_PRINT(REG_RXDLSA);
> +       REG_PRINT(REG_MCMDR);
> +       REG_PRINT(REG_MIID);
> +       REG_PRINT(REG_MIIDA);
> +       REG_PRINT(REG_FFTCR);
> +       REG_PRINT(REG_TSDR);
> +       REG_PRINT(REG_RSDR);
> +       REG_PRINT(REG_DMARFC);
> +       REG_PRINT(REG_MIEN);
> +       REG_PRINT(REG_MISTA);
> +       REG_PRINT(REG_MGSTA);
> +       REG_PRINT(REG_MPCNT);
> +       writel(0x7FFF, (ether->reg + REG_MPCNT));
> +       REG_PRINT(REG_MRPC);
> +       REG_PRINT(REG_MRPCC);
> +       REG_PRINT(REG_MREPC);
> +       REG_PRINT(REG_DMARFS);
> +       REG_PRINT(REG_CTXDSA);
> +       REG_PRINT(REG_CTXBSA);
> +       REG_PRINT(REG_CRXDSA);
> +       REG_PRINT(REG_CRXBSA);
> +       REG_PRINT(REG_RXFSM);
> +       REG_PRINT(REG_TXFSM);
> +       REG_PRINT(REG_FSM0);
> +       REG_PRINT(REG_FSM1);
> +       REG_PRINT(REG_DCR);
> +       REG_PRINT(REG_DMMIR);
> +       REG_PRINT(REG_BISTR);
> +       DUMP_PRINT("\n");
> +
> +       DUMP_PRINT("netif_queue %s\n\n", netif_queue_stopped(netdev) ?
> +                                       "Stopped" : "Running");
> +       if (ether->rdesc)
> +               DUMP_PRINT("napi is %s\n\n", test_bit(NAPI_STATE_SCHED,
> +                                                     &ether->napi.state) ?
> +                                                       "scheduled" :
> +                                                       "not scheduled");
> +
> +       txd_offset = (readl((ether->reg + REG_CTXDSA)) -
> +                     readl((ether->reg + REG_TXDLSA))) /
> +               sizeof(struct npcm7xx_txbd);
> +       DUMP_PRINT("TXD offset    %6d\n", txd_offset);
> +       DUMP_PRINT("cur_tx        %6d\n", ether->cur_tx);
> +       DUMP_PRINT("finish_tx     %6d\n", ether->finish_tx);
> +       DUMP_PRINT("pending_tx    %6d\n", ether->pending_tx);
> +       /* debug counters */
> +       DUMP_PRINT("tx_tdu        %6d\n", ether->tx_tdu);
> +       ether->tx_tdu = 0;
> +       DUMP_PRINT("tx_tdu_i      %6d\n", ether->tx_tdu_i);
> +       ether->tx_tdu_i = 0;
> +       DUMP_PRINT("tx_cp_i       %6d\n", ether->tx_cp_i);
> +        ether->tx_cp_i = 0;
> +       DUMP_PRINT("tx_int_count  %6d\n", ether->tx_int_count);
> +       ether->tx_int_count = 0;
> +       DUMP_PRINT("count_xmit tx %6d\n", ether->count_xmit);
> +       ether->count_xmit = 0;
> +       DUMP_PRINT("count_finish  %6d\n", ether->count_finish);
> +       ether->count_finish = 0;
> +       DUMP_PRINT("\n");
> +
> +       rxd_offset = (readl((ether->reg + REG_CRXDSA)) -
> +                     readl((ether->reg + REG_RXDLSA)))
> +               / sizeof(struct npcm7xx_txbd);
> +       DUMP_PRINT("RXD offset    %6d\n", rxd_offset);
> +       DUMP_PRINT("cur_rx        %6d\n", ether->cur_rx);
> +       DUMP_PRINT("rx_err        %6d\n", ether->rx_err);
> +       ether->rx_err = 0;
> +       DUMP_PRINT("rx_berr       %6d\n", ether->rx_berr);
> +       ether->rx_berr = 0;
> +       DUMP_PRINT("rx_stuck      %6d\n", ether->rx_stuck);
> +       ether->rx_stuck = 0;
> +       DUMP_PRINT("rdu           %6d\n", ether->rdu);
> +       ether->rdu = 0;
> +       DUMP_PRINT("rxov rx       %6d\n", ether->rxov);
> +       ether->rxov = 0;
> +       /* debug counters */
> +       DUMP_PRINT("rx_int_count  %6d\n", ether->rx_int_count);
> +       ether->rx_int_count = 0;
> +       DUMP_PRINT("rx_err_count  %6d\n", ether->rx_err_count);
> +       ether->rx_err_count = 0;

Basic counters like tx_packets and rx_errors are probably better
exported regardless of debug level as net_device_stats. And then don't
need to be copied in debug output.

Less standard counters like tx interrupt count are probably better
candidates for ethtool -S.

> +#ifdef CONFIG_NPCM7XX_EMC_ETH_DEBUG
> +static void npcm7xx_info_print(struct net_device *netdev)
> +{
> +       char *emc_dump_buf;
> +       int count;
> +       struct npcm7xx_ether *ether;
> +       struct platform_device *pdev;
> +       char c;
> +       char *tmp_buf;
> +       const size_t print_size = 5 * PAGE_SIZE;
> +
> +       ether = netdev_priv(netdev);
> +       pdev = ether->pdev;
> +
> +       emc_dump_buf = kmalloc(print_size, GFP_KERNEL);
> +       if (!emc_dump_buf)
> +               return;
> +
> +       tmp_buf = emc_dump_buf;
> +       count = npcm7xx_info_dump(emc_dump_buf, print_size, netdev);
> +       while (count > 512) {
> +               c = tmp_buf[512];
> +               tmp_buf[512] = 0;
> +               dev_info(&pdev->dev, "%s", tmp_buf);
> +               tmp_buf += 512;
> +               tmp_buf[0] = c;
> +               count -= 512;

Missing closing parenthesis.

Also, why this buffering to printk?

> +static void npcm7xx_write_cam(struct net_device *netdev,
> +                             unsigned int x, unsigned char *pval)
> +{
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +       __le32 msw, lsw;
> +
> +       msw = (pval[0] << 24) | (pval[1] << 16) | (pval[2] << 8) | pval[3];
> +
> +       lsw = (pval[4] << 24) | (pval[5] << 16);

Does __le32 plus this explicit shifting define host endianness? Better
to keep independent?

> +
> +       writel(lsw, (ether->reg + REG_CAML_BASE) + x * CAM_ENTRY_SIZE);
> +       writel(msw, (ether->reg + REG_CAMM_BASE) + x * CAM_ENTRY_SIZE);
> +       dev_dbg(&ether->pdev->dev,
> +               "REG_CAML_BASE = 0x%08X REG_CAMM_BASE = 0x%08X", lsw, msw);
> +}
> +
> +static struct sk_buff *get_new_skb(struct net_device *netdev, u32 i)
> +{
> +       __le32 buffer;
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +       struct sk_buff *skb = netdev_alloc_skb(netdev,
> +               roundup(MAX_PACKET_SIZE_W_CRC, 4));
> +
> +       if (unlikely(!skb)) {
> +               if (net_ratelimit())
> +                       netdev_warn(netdev, "failed to allocate rx skb\n");

can use net_warn_ratelimited (here and elsewhere)

> +               buffer = ether->rx_scratch_dma;
> +       } else {
> +               /* Do not unmark the following skb_reserve() Receive Buffer
> +                * Starting Address must be aligned to 4 bytes and the following
> +                * line if unmarked will make it align to 2 and this likely will
> +                * hult the RX and crash the linux

halt?

> +                * skb_reserve(skb, NET_IP_ALIGN);
> +                */
> +               skb->dev = netdev;
> +               buffer = dma_map_single(&netdev->dev,
> +                                       skb->data,
> +                                       roundup(MAX_PACKET_SIZE_W_CRC, 4),
> +                                       DMA_FROM_DEVICE);
> +               if (unlikely(dma_mapping_error(&netdev->dev, buffer))) {
> +                       if (net_ratelimit())
> +                               netdev_err(netdev, "failed to map rx page\n");
> +                       dev_kfree_skb_any(skb);
> +                       buffer = ether->rx_scratch_dma;
> +                       skb = NULL;
> +               }
> +       }
> +       ether->rx_skb[i] = skb;
> +       ether->rdesc[i].buffer = buffer;
> +
> +       return skb;
> +}
> +

> +static int npcm7xx_ether_close(struct net_device *netdev)
> +{
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +
> +       npcm7xx_return_default_idle(netdev);
> +
> +       if (ether->phy_dev)
> +               phy_stop(ether->phy_dev);
> +       else if (ether->use_ncsi)
> +               ncsi_stop_dev(ether->ncsidev);
> +
> +       msleep(20);
> +
> +       free_irq(ether->txirq, netdev);
> +       free_irq(ether->rxirq, netdev);
> +
> +       netif_stop_queue(netdev);
> +       napi_disable(&ether->napi);

Cleanup state in reverse of allocation.

> +static int npcm7xx_ether_start_xmit(struct sk_buff *skb, struct net_device *netdev)
> +{
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +       struct npcm7xx_txbd *txbd;
> +       unsigned long flags;
> +
> +       ether->count_xmit++;
> +
> +       /* Insert new buffer */
> +       txbd = (ether->tdesc + ether->cur_tx);
> +       txbd->buffer = dma_map_single(&netdev->dev, skb->data, skb->len,
> +                                     DMA_TO_DEVICE);
> +       ether->tx_skb[ether->cur_tx]  = skb;
> +       if (skb->len > MAX_PACKET_SIZE)
> +               dev_err(&ether->pdev->dev,
> +                       "skb->len (= %d) > MAX_PACKET_SIZE (= %d)\n",
> +                       skb->len, MAX_PACKET_SIZE);

> +       txbd->sl = skb->len > MAX_PACKET_SIZE ? MAX_PACKET_SIZE : skb->len;

Check for errors before mapping to device, and drop packet? Probably
don't want to output truncated packets.

Also rate limit such messages.

> +       dma_wmb();
> +
> +       txbd->mode = TX_OWN_DMA | PADDINGMODE | CRCMODE;
> +
> +       /* make sure that data is in memory before we trigger TX */
> +       wmb();
> +
> +       /* trigger TX */
> +       writel(ENSTART, (ether->reg + REG_TSDR));
> +
> +       if (++ether->cur_tx >= TX_QUEUE_LEN)
> +               ether->cur_tx = 0;
> +
> +       spin_lock_irqsave(&ether->lock, flags);
> +       ether->pending_tx++;
> +
> +       /* sometimes we miss the tx interrupt due to HW issue, so NAPI will not
> +        * clean the pending tx, so we clean it also here
> +        */
> +       npcm7xx_clean_tx(netdev, true);
> +
> +       if (ether->pending_tx >= TX_QUEUE_LEN - 1) {
> +               __le32 reg_mien;
> +               unsigned int index_to_wake = ether->cur_tx +
> +                       ((TX_QUEUE_LEN * 3) / 4);
> +
> +               if (index_to_wake >= TX_QUEUE_LEN)
> +                       index_to_wake -= TX_QUEUE_LEN;
> +
> +               txbd = (ether->tdesc + index_to_wake);
> +               txbd->mode = TX_OWN_DMA | PADDINGMODE | CRCMODE | MACTXINTEN;
> +
> +               /* make sure that data is in memory before we trigger TX */
> +               wmb();
> +
> +               /* Clear TDU interrupt */
> +               writel(MISTA_TDU, (ether->reg + REG_MISTA));
> +
> +               /* due to HW issue somtimes, we miss the TX interrupt we just

somtimes -> sometimes

> +                * set (MACTXINTEN), so we also set TDU for Transmit
> +                * Descriptor Unavailable interrupt
> +                */
> +               reg_mien = readl((ether->reg + REG_MIEN));
> +               if (reg_mien != 0)
> +                       /* Enable TDU interrupt */
> +                       writel(reg_mien | ENTDU, (ether->reg + REG_MIEN));
> +
> +               ether->tx_tdu++;
> +               netif_stop_queue(netdev);
> +       }
> +
> +       spin_unlock_irqrestore(&ether->lock, flags);
> +
> +       return 0;
> +}
> +
> +static irqreturn_t npcm7xx_tx_interrupt(int irq, void *dev_id)
> +{
> +       struct npcm7xx_ether *ether;
> +       struct platform_device *pdev;
> +       struct net_device *netdev;
> +       __le32 status;
> +       unsigned long flags;
> +
> +       netdev = dev_id;
> +       ether = netdev_priv(netdev);
> +       pdev = ether->pdev;
> +
> +       npcm7xx_get_and_clear_int(netdev, &status, 0xFFFF0000);
> +
> +       ether->tx_int_count++;
> +
> +       if (status & MISTA_EXDEF)
> +               dev_err(&pdev->dev, "emc defer exceed interrupt status=0x%08X\n"
> +                       , status);
> +       else if (status & MISTA_TXBERR) {
> +               dev_err(&pdev->dev, "emc bus error interrupt status=0x%08X\n",
> +                       status);
> +#ifdef CONFIG_NPCM7XX_EMC_ETH_DEBUG
> +               npcm7xx_info_print(netdev);
> +#endif
> +               spin_lock_irqsave(&ether->lock, flags);

irqsave in hard interrupt context?

> +               writel(0, (ether->reg + REG_MIEN)); /* disable any interrupt */
> +               spin_unlock_irqrestore(&ether->lock, flags);
> +               ether->need_reset = 1;
> +       } else if (status & ~(MISTA_TXINTR | MISTA_TXCP | MISTA_TDU))
> +               dev_err(&pdev->dev, "emc other error interrupt status=0x%08X\n",
> +                       status);
> +
> +    /* if we got MISTA_TXCP | MISTA_TDU remove those interrupt and call napi */

The goal of napi is to keep interrupts disabled until napi completes.

> +       if (status & (MISTA_TXCP | MISTA_TDU) &
> +           readl((ether->reg + REG_MIEN))) {
> +               __le32 reg_mien;
> +
> +               spin_lock_irqsave(&ether->lock, flags);
> +               reg_mien = readl((ether->reg + REG_MIEN));
> +               if (reg_mien & ENTDU)
> +                       /* Disable TDU interrupt */
> +                       writel(reg_mien & (~ENTDU), (ether->reg + REG_MIEN));
> +
> +               spin_unlock_irqrestore(&ether->lock, flags);
> +
> +               if (status & MISTA_TXCP)
> +                       ether->tx_cp_i++;
> +               if (status & MISTA_TDU)
> +                       ether->tx_tdu_i++;
> +       } else {
> +               dev_dbg(&pdev->dev, "status=0x%08X\n", status);
> +       }
> +
> +       napi_schedule(&ether->napi);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t npcm7xx_rx_interrupt(int irq, void *dev_id)
> +{
> +       struct net_device *netdev = (struct net_device *)dev_id;
> +       struct npcm7xx_ether *ether = netdev_priv(netdev);
> +       struct platform_device *pdev = ether->pdev;
> +       __le32 status;
> +       unsigned long flags;
> +       unsigned int any_err = 0;
> +       __le32 rxfsm;
> +
> +       npcm7xx_get_and_clear_int(netdev, &status, 0xFFFF);

Same here

> +static int npcm7xx_poll(struct napi_struct *napi, int budget)
> +{
> +       struct npcm7xx_ether *ether =
> +               container_of(napi, struct npcm7xx_ether, napi);
> +       struct npcm7xx_rxbd *rxbd;
> +       struct net_device *netdev = ether->netdev;
> +       struct platform_device *pdev = ether->pdev;
> +       struct sk_buff *s;
> +       unsigned int length;
> +       __le32 status;
> +       unsigned long flags;
> +       int rx_cnt = 0;
> +       int complete = 0;
> +       unsigned int rx_offset = (readl((ether->reg + REG_CRXDSA)) -
> +                                 ether->start_rx_ptr) /
> +                               sizeof(struct npcm7xx_txbd);
> +       unsigned int local_count = (rx_offset >= ether->cur_rx) ?
> +               rx_offset - ether->cur_rx : rx_offset +
> +               RX_QUEUE_LEN - ether->cur_rx;
> +
> +       if (local_count > ether->max_waiting_rx)
> +               ether->max_waiting_rx = local_count;
> +
> +       if (local_count > (4 * RX_POLL_SIZE))
> +               /* we are porbably in a storm of short packets and we don't

porbably - probably

> +                * want to get into RDU since short packets in RDU cause
> +                * many RXOV which may cause EMC halt, so we filter out all
> +                * coming packets
> +                */
> +               writel(0, (ether->reg + REG_CAMCMR));
> +
> +       if (local_count <= budget)
> +               /* we can restore accepting of packets */
> +               writel(ether->camcmr, (ether->reg + REG_CAMCMR));
> +
> +       spin_lock_irqsave(&ether->lock, flags);
> +       npcm7xx_clean_tx(netdev, false);
> +       spin_unlock_irqrestore(&ether->lock, flags);
> +
> +       rxbd = (ether->rdesc + ether->cur_rx);
> +
> +       while (rx_cnt < budget) {
> +               status = rxbd->sl;
> +               if ((status & RX_OWN_DMA) == RX_OWN_DMA) {
> +                       complete = 1;
> +                       break;
> +               }
> +               /* for debug puposes we save the previous value */

puposes -> purposes

> +               rxbd->reserved = status;
> +               s = ether->rx_skb[ether->cur_rx];
> +               length = status & 0xFFFF;
> +
> +               /* If VLAN is not supporte RXDS_PTLE (packet too long) is also

supporte -> supported (stopping pointing out typos after this).

> +static const struct net_device_ops npcm7xx_ether_netdev_ops = {
> +       .ndo_open               = npcm7xx_ether_open,
> +       .ndo_stop               = npcm7xx_ether_close,
> +       .ndo_start_xmit         = npcm7xx_ether_start_xmit,
> +       .ndo_get_stats          = npcm7xx_ether_stats,
> +       .ndo_set_rx_mode        = npcm7xx_ether_set_rx_mode,
> +       .ndo_set_mac_address    = npcm7xx_set_mac_address,
> +       .ndo_do_ioctl           = npcm7xx_ether_ioctl,
> +       .ndo_validate_addr      = eth_validate_addr,
> +       .ndo_change_mtu         = eth_change_mtu,

This is marked as deprecated. Also in light of the hardcoded
MAX_PACKET_SIZE, probably want to set dev->max_mtu.

> +static int npcm7xx_ether_probe(struct platform_device *pdev)
> +{
> +       struct npcm7xx_ether *ether;
> +       struct net_device *netdev;
> +       int error;
> +
> +       struct clk *emc_clk = NULL;
> +       struct device_node *np = pdev->dev.of_node;
> +
> +       pdev->id = of_alias_get_id(np, "ethernet");
> +       if (pdev->id < 0)
> +               pdev->id = 0;
> +
> +       emc_clk = devm_clk_get(&pdev->dev, NULL);
> +
> +       if (IS_ERR(emc_clk))
> +               return PTR_ERR(emc_clk);
> +
> +       /* Enable Clock */
> +       clk_prepare_enable(emc_clk);
> +
> +       error = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> +       if (error)
> +               return -ENODEV;
> +
> +       netdev = alloc_etherdev(sizeof(struct npcm7xx_ether));
> +       if (!netdev)
> +               return -ENOMEM;
> +
> +       ether = netdev_priv(netdev);
> +
> +       ether->reset = devm_reset_control_get(&pdev->dev, NULL);
> +       if (IS_ERR(ether->reset))
> +               return PTR_ERR(ether->reset);

Memory leak on error path

Also missing netif_napi_del in npcm7xx_ether_remove?

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