Re: [PATCH v8 3/3] net: ax88796c: ASIX AX88796C SPI Ethernet Adapter Driver

From: Jakub Kicinski
Date: Fri Dec 04 2020 - 22:38:41 EST

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In reply to: Łukasz Stelmach: "[PATCH v8 3/3] net: ax88796c: ASIX AX88796C SPI Ethernet Adapter Driver"
Next in thread: Łukasz Stelmach: "[PATCH v8 1/3] dt-bindings: vendor-prefixes: Add asix prefix"
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On Wed, 2 Dec 2020 22:47:09 +0100 Łukasz Stelmach wrote:
> ASIX AX88796[1] is a versatile ethernet adapter chip, that can be
> connected to a CPU with a 8/16-bit bus or with an SPI. This driver
> supports SPI connection.
>
> The driver has been ported from the vendor kernel for ARTIK5[2]
> boards. Several changes were made to adapt it to the current kernel
> which include:
>
> + updated DT configuration,
> + clock configuration moved to DT,
> + new timer, ethtool and gpio APIs,
> + dev_* instead of pr_* and custom printk() wrappers,
> + removed awkward vendor power managemtn.
> + introduced ethtool tunable to control SPI compression
>
> [1] https://www.asix.com.tw/products.php?op=pItemdetail&PItemID=104;65;86&PLine=65
> [2] https://git.tizen.org/cgit/profile/common/platform/kernel/linux-3.10-artik/
>
> The other ax88796 driver is for NE2000 compatible AX88796L chip. These
> chips are not compatible. Hence, two separate drivers are required.
>
> Signed-off-by: Łukasz Stelmach <l.stelmach@xxxxxxxxxxx>
> Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

> + case ETHTOOL_SPI_COMPRESSION:
> + if (netif_running(ndev))
> + return -EBUSY;
> + if ((*(u32 *)data) != 1)
> + return -EINVAL;
> + ax_local->capabilities &= ~AX_CAP_COMP;
> + ax_local->capabilities |= (*(u32 *)data) == 1 ? AX_CAP_COMP : 0;

Since you're just using a single bit of information please use
a private driver flag.

> + headroom = skb_headroom(skb);
> + tailroom = skb_tailroom(skb);
> + padlen = ((pkt_len + 3) & 0x7FC) - pkt_len;

round_up(pkt_len, 4) - pkt_len;

> + tol_len = ((pkt_len + 3) & 0x7FC) +
> + TX_OVERHEAD + TX_EOP_SIZE + spi_len;

Ditto

> + seq_num = ++ax_local->seq_num & 0x1F;
> +
> + info = (struct tx_pkt_info *)skb->cb;
> + info->pkt_len = pkt_len;
> +
> + if ((!skb_cloned(skb)) &&
> + (headroom >= (TX_OVERHEAD + spi_len)) &&
> + (tailroom >= (padlen + TX_EOP_SIZE))) {

> + } else {

I think you can just use pskb_expand_head() instead of all this

> + tx_skb = alloc_skb(tol_len, GFP_KERNEL);
> + if (!tx_skb)
> + return NULL;
> +
> + /* Write SPI TXQ header */
> + memcpy(skb_put(tx_skb, spi_len), ax88796c_tx_cmd_buf, spi_len);
> +
> + info->seq_num = seq_num;
> + ax88796c_proc_tx_hdr(info, skb->ip_summed);
> +
> + /* SOP and SEG header */
> + memcpy(skb_put(tx_skb, TX_OVERHEAD),
> + &info->sop, TX_OVERHEAD);
> +
> + /* Packet */
> + memcpy(skb_put(tx_skb, ((pkt_len + 3) & 0xFFFC)),
> + skb->data, pkt_len);
> +
> + /* EOP header */
> + memcpy(skb_put(tx_skb, TX_EOP_SIZE),
> + &info->eop, TX_EOP_SIZE);
> +
> + skb_unlink(skb, q);
> + dev_kfree_skb(skb);
> + }

> +static void
> +ax88796c_skb_return(struct ax88796c_device *ax_local, struct sk_buff *skb,
> + struct rx_header *rxhdr)
> +{
> + struct net_device *ndev = ax_local->ndev;
> + int status;
> +
> + do {
> + if (!(ndev->features & NETIF_F_RXCSUM))
> + break;
> +
> + /* checksum error bit is set */
> + if ((rxhdr->flags & RX_HDR3_L3_ERR) ||
> + (rxhdr->flags & RX_HDR3_L4_ERR))
> + break;
> +
> + /* Other types may be indicated by more than one bit. */
> + if ((rxhdr->flags & RX_HDR3_L4_TYPE_TCP) ||
> + (rxhdr->flags & RX_HDR3_L4_TYPE_UDP))
> + skb->ip_summed = CHECKSUM_UNNECESSARY;
> + } while (0);
> +
> + ax_local->stats.rx_packets++;
> + ax_local->stats.rx_bytes += skb->len;
> + skb->dev = ndev;
> +
> + skb->truesize = skb->len + sizeof(struct sk_buff);

Why do you modify truesize?

> + skb->protocol = eth_type_trans(skb, ax_local->ndev);
> +
> + netif_info(ax_local, rx_status, ndev, "< rx, len %zu, type 0x%x\n",
> + skb->len + sizeof(struct ethhdr), skb->protocol);
> +
> + status = netif_rx_ni(skb);
> + if (status != NET_RX_SUCCESS)
> + netif_info(ax_local, rx_err, ndev,
> + "netif_rx status %d\n", status);
> +}
> +
> +static void
> +ax88796c_rx_fixup(struct ax88796c_device *ax_local, struct sk_buff *rx_skb)
> +{
> + struct rx_header *rxhdr = (struct rx_header *)rx_skb->data;
> + struct net_device *ndev = ax_local->ndev;
> + u16 len;
> +
> + be16_to_cpus(&rxhdr->flags_len);
> + be16_to_cpus(&rxhdr->seq_lenbar);
> + be16_to_cpus(&rxhdr->flags);
> +
> + if ((((short)rxhdr->flags_len) & RX_HDR1_PKT_LEN) !=
> + (~((short)rxhdr->seq_lenbar) & 0x7FF)) {

Why do you cast these values to signed types?
Is the casting necessary at all?

> + netif_err(ax_local, rx_err, ndev, "Header error\n");
> +
> + ax_local->stats.rx_frame_errors++;
> + kfree_skb(rx_skb);
> + return;
> + }
> +
> + if ((rxhdr->flags_len & RX_HDR1_MII_ERR) ||
> + (rxhdr->flags_len & RX_HDR1_CRC_ERR)) {
> + netif_err(ax_local, rx_err, ndev, "CRC or MII error\n");
> +
> + ax_local->stats.rx_crc_errors++;
> + kfree_skb(rx_skb);
> + return;
> + }
> +
> + len = rxhdr->flags_len & RX_HDR1_PKT_LEN;
> + if (netif_msg_pktdata(ax_local)) {
> + char pfx[IFNAMSIZ + 7];
> +
> + snprintf(pfx, sizeof(pfx), "%s: ", ndev->name);
> + netdev_info(ndev, "RX data, total len %d, packet len %d\n",
> + rx_skb->len, len);
> +
> + netdev_info(ndev, " Dump RX packet header:");
> + print_hex_dump(KERN_INFO, pfx, DUMP_PREFIX_OFFSET, 16, 1,
> + rx_skb->data, sizeof(*rxhdr), 0);
> +
> + netdev_info(ndev, " Dump RX packet:");
> + print_hex_dump(KERN_INFO, pfx, DUMP_PREFIX_OFFSET, 16, 1,
> + rx_skb->data + sizeof(*rxhdr), len, 0);
> + }
> +
> + skb_pull(rx_skb, sizeof(*rxhdr));
> + __pskb_trim(rx_skb, len);

Why __pskb_trim? skb_trim() should do.

> + return ax88796c_skb_return(ax_local, rx_skb, rxhdr);

please drop the "return", both caller and callee are void.

> +}
> +
> +static int ax88796c_receive(struct net_device *ndev)
> +{
> + struct ax88796c_device *ax_local = to_ax88796c_device(ndev);
> + struct skb_data *entry;
> + u16 w_count, pkt_len;
> + struct sk_buff *skb;
> + u8 pkt_cnt;
> +
> + WARN_ON(!mutex_is_locked(&ax_local->spi_lock));
> +
> + /* check rx packet and total word count */
> + AX_WRITE(&ax_local->ax_spi, AX_READ(&ax_local->ax_spi, P0_RTWCR)
> + | RTWCR_RX_LATCH, P0_RTWCR);
> +
> + pkt_cnt = AX_READ(&ax_local->ax_spi, P0_RXBCR2) & RXBCR2_PKT_MASK;
> + if (!pkt_cnt)
> + return 0;
> +
> + pkt_len = AX_READ(&ax_local->ax_spi, P0_RCPHR) & 0x7FF;
> +
> + w_count = ((pkt_len + 6 + 3) & 0xFFFC) >> 1;
> +
> + skb = alloc_skb((w_count * 2), GFP_ATOMIC);

netdev_alloc_skb()

> + if (!skb) {
> + AX_WRITE(&ax_local->ax_spi, RXBCR1_RXB_DISCARD, P0_RXBCR1);
> + return 0;
> + }
> + entry = (struct skb_data *)skb->cb;
> +
> + AX_WRITE(&ax_local->ax_spi, RXBCR1_RXB_START | w_count, P0_RXBCR1);
> +
> + axspi_read_rxq(&ax_local->ax_spi,
> + skb_put(skb, w_count * 2), skb->len);
> +
> + /* Check if rx bridge is idle */
> + if ((AX_READ(&ax_local->ax_spi, P0_RXBCR2) & RXBCR2_RXB_IDLE) == 0) {
> + netif_err(ax_local, rx_err, ndev,
> + "Rx Bridge is not idle\n");
> + AX_WRITE(&ax_local->ax_spi, RXBCR2_RXB_REINIT, P0_RXBCR2);
> +
> + entry->state = rx_err;
> + } else {
> + entry->state = rx_done;
> + }
> +
> + AX_WRITE(&ax_local->ax_spi, ISR_RXPKT, P0_ISR);
> +
> + ax88796c_rx_fixup(ax_local, skb);
> +
> + return 1;
> +}

> +static irqreturn_t ax88796c_interrupt(int irq, void *dev_instance)
> +{
> + struct ax88796c_device *ax_local;
> + struct net_device *ndev;
> +
> + ndev = dev_instance;
> + if (!ndev) {
> + pr_err("irq %d for unknown device.\n", irq);
> + return IRQ_RETVAL(0);
> + }
> + ax_local = to_ax88796c_device(ndev);
> +
> + disable_irq_nosync(irq);
> +
> + netif_dbg(ax_local, intr, ndev, "Interrupt occurred\n");
> +
> + set_bit(EVENT_INTR, &ax_local->flags);
> + schedule_work(&ax_local->ax_work);
> +
> + return IRQ_HANDLED;
> +}

Since you always punt to a workqueue did you consider just using
threaded interrupts instead?

Also you're not checking if this is actually your devices IRQ that
triggered. You can't set IRQF_SHARED.

> +static int
> +ax88796c_open(struct net_device *ndev)
> +{
> + struct ax88796c_device *ax_local = to_ax88796c_device(ndev);
> + unsigned long irq_flag = IRQF_SHARED;
> + int fc = AX_FC_NONE;
> + int ret;
> +
> + ret = request_irq(ndev->irq, ax88796c_interrupt,
> + irq_flag, ndev->name, ndev);
> + if (ret) {
> + netdev_err(ndev, "unable to get IRQ %d (errno=%d).\n",
> + ndev->irq, ret);
> + return ret;
> + }
> +
> + mutex_lock(&ax_local->spi_lock);
> +
> + ret = ax88796c_soft_reset(ax_local);
> + if (ret < 0) {
> + mutex_unlock(&ax_local->spi_lock);
> + return ret;

What frees the IRQ?

> + }
> + ax_local->seq_num = 0x1f;
> +
> + ax88796c_set_mac_addr(ndev);
> + ax88796c_set_csums(ax_local);
> +
> + /* Disable stuffing packet */
> + AX_WRITE(&ax_local->ax_spi,
> + AX_READ(&ax_local->ax_spi, P1_RXBSPCR)
> + & ~RXBSPCR_STUF_ENABLE, P1_RXBSPCR);

Please use a temporary variable or create a RMW helper.

> + /* Enable RX packet process */
> + AX_WRITE(&ax_local->ax_spi, RPPER_RXEN, P1_RPPER);
> +
> + AX_WRITE(&ax_local->ax_spi, AX_READ(&ax_local->ax_spi, P0_FER)
> + | FER_RXEN | FER_TXEN | FER_BSWAP | FER_IRQ_PULL, P0_FER);

Ditto. etc.

> + ndev = devm_alloc_etherdev(&spi->dev, sizeof(*ax_local));
> + if (!ndev)
> + return -ENOMEM;
> +
> + SET_NETDEV_DEV(ndev, &spi->dev);
> +
> + ax_local = to_ax88796c_device(ndev);
> + memset(ax_local, 0, sizeof(*ax_local));

No need to zero out netdev priv, it's zalloced.

> + mutex_lock(&ax_local->spi_lock);
> +
> + /* ax88796c gpio reset */
> + ax88796c_hard_reset(ax_local);
> +
> + /* Reset AX88796C */
> + ret = ax88796c_soft_reset(ax_local);
> + if (ret < 0) {
> + ret = -ENODEV;
> + goto err;
> + }
> + /* Check board revision */
> + temp = AX_READ(&ax_local->ax_spi, P2_CRIR);
> + if ((temp & 0xF) != 0x0) {
> + dev_err(&spi->dev, "spi read failed: %d\n", temp);
> + ret = -ENODEV;
> + goto err;
> + }

These jump out without releasing the lock.

> + /* Disable power saving */
> + AX_WRITE(&ax_local->ax_spi, (AX_READ(&ax_local->ax_spi, P0_PSCR)
> + & PSCR_PS_MASK) | PSCR_PS_D0, P0_PSCR);

This is asking for a temporary variable or a RMW helper.

> + u8 plat_endian;
> + #define PLAT_LITTLE_ENDIAN 0
> + #define PLAT_BIG_ENDIAN 1

Why do you store this little nugget of information?

> +/* Tx headers structure */
> +struct tx_sop_header {
> + /* bit 15-11: flags, bit 10-0: packet length */
> + u16 flags_len;
> + /* bit 15-11: sequence number, bit 11-0: packet length bar */
> + u16 seq_lenbar;
> +} __packed;
> +
> +struct tx_segment_header {
> + /* bit 15-14: flags, bit 13-11: segment number */
> + /* bit 10-0: segment length */
> + u16 flags_seqnum_seglen;
> + /* bit 15-14: end offset, bit 13-11: start offset */
> + /* bit 10-0: segment length bar */
> + u16 eo_so_seglenbar;
> +} __packed;
> +
> +struct tx_eop_header {
> + /* bit 15-11: sequence number, bit 10-0: packet length */
> + u16 seq_len;
> + /* bit 15-11: sequence number bar, bit 10-0: packet length bar */
> + u16 seqbar_lenbar;
> +} __packed;
> +
> +struct tx_pkt_info {
> + struct tx_sop_header sop;
> + struct tx_segment_header seg;
> + struct tx_eop_header eop;
> + u16 pkt_len;
> + u16 seq_num;
> +} __packed;
> +
> +/* Rx headers structure */
> +struct rx_header {
> + u16 flags_len;
> + u16 seq_lenbar;
> + u16 flags;
> +} __packed;

These all look like multiple of 2 bytes. Why do they need to be packed?

> +u16 axspi_read_reg(struct axspi_data *ax_spi, u8 reg)
> +{
> + int ret;
> + int len = ax_spi->comp ? 3 : 4;
> +
> + ax_spi->cmd_buf[0] = 0x03; /* OP code read register */
> + ax_spi->cmd_buf[1] = reg; /* register address */
> + ax_spi->cmd_buf[2] = 0xFF; /* dumy cycle */
> + ax_spi->cmd_buf[3] = 0xFF; /* dumy cycle */
> + ret = spi_write_then_read(ax_spi->spi,
> + ax_spi->cmd_buf, len,
> + ax_spi->rx_buf, 2);
> + if (ret)
> + dev_err(&ax_spi->spi->dev, "%s() failed: ret = %d\n", __func__, ret);
> + else
> + le16_to_cpus(ax_spi->rx_buf);
> +
> + return *(u16 *)ax_spi->rx_buf;

No need to return some specific pattern on failure? Like 0xffff?

Next message: Daeho Jeong: "Re: [f2fs-dev] [PATCH] f2fs: fix race of pending_pages in decompression"
Previous message: mark gross: "Re: [PATCH 03/22] keembay-ipc: Add Keem Bay IPC module"
In reply to: Łukasz Stelmach: "[PATCH v8 3/3] net: ax88796c: ASIX AX88796C SPI Ethernet Adapter Driver"
Next in thread: Łukasz Stelmach: "[PATCH v8 1/3] dt-bindings: vendor-prefixes: Add asix prefix"
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