Re: [RFC v2 PATCH 06/10] net: ti: prueth: Adds HW timestamping support for PTP using PRU-ICSS IEP module

Simon Horman
2025-01-31T10:35:35Z

On Fri, Jan 24, 2025 at 07:10:52PM +0530, Basharath Hussain Khaja wrote:
> From: Roger Quadros <rogerq@ti.com>
>
> PRU-ICSS IEP module, which is capable of timestamping RX and
> TX packets at HW level, is used for time synchronization by PTP4L.
>
> This change includes interaction between firmware and user space
> application (ptp4l) with required packet timestamps. The driver
> initializes the PRU firmware with appropriate mode and configuration
> flags. Firmware updates local registers with the flags set by driver
> and uses for further operation. RX SOF timestamp comes along with
> packet and firmware will rise interrupt with TX SOF timestamp after
> pushing the packet on to the wire.
>
> IEP driver is available in upstream and we are reusing for hardware
> configuration for ICSSM as well. On top of that we have extended it
> with the changes for AM57xx SoC.
>
> Extended ethtool for reading HW timestamping capability of the PRU
> interfaces.
>
> Currently ordinary clock (OC) configuration has been validated with
> Linux ptp4l.
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> Signed-off-by: Andrew F. Davis <afd@ti.com>
> Signed-off-by: Parvathi Pudi <parvathi@couthit.com>
> Signed-off-by: Basharath Hussain Khaja <basharath@couthit.com>

...

> diff --git a/drivers/net/ethernet/ti/icssm/icssm_prueth.c b/drivers/net/ethernet/ti/icssm/icssm_prueth.c

...

> @@ -682,9 +899,22 @@ int icssm_emac_rx_packet(struct prueth_emac *emac, u16 *bd_rd_ptr,
> src_addr += actual_pkt_len;
> }
>
> + if (pkt_info->timestamp) {
> + src_addr = (void *)roundup((uintptr_t)src_addr,
> + ICSS_BLOCK_SIZE);

Can PTR_ALIGN() be used here?

> + dst_addr = &ts;
> + memcpy(dst_addr, src_addr, sizeof(ts));
> + }
> +
> if (!pkt_info->sv_frame) {
> skb_put(skb, actual_pkt_len);
>
> + if (icssm_prueth_ptp_rx_ts_is_enabled(emac) &&
> + pkt_info->timestamp) {
> + ssh = skb_hwtstamps(skb);
> + memset(ssh, 0, sizeof(*ssh));
> + ssh->hwtstamp = ns_to_ktime(ts);
> + }
> /* send packet up the stack */
> skb->protocol = eth_type_trans(skb, ndev);
> local_bh_disable();

The code preceding the hunk below is:

static int icssm_emac_request_irqs(struct prueth_emac *emac)
{
struct net_device *ndev = emac->ndev;
int ret;

ret = request_threaded_irq(emac->rx_irq, NULL, icssm_emac_rx_thread,
IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
ndev->name, ndev);
if (ret) {
netdev_err(ndev, "unable to request RX IRQ\n");
return ret;
}

> @@ -855,9 +1085,64 @@ static int icssm_emac_request_irqs(struct prueth_emac *emac)
> return ret;
> }
>
> + if (emac->emac_ptp_tx_irq) {
> + ret = request_threaded_irq(emac->emac_ptp_tx_irq,
> + icssm_prueth_ptp_tx_irq_handle,
> + icssm_prueth_ptp_tx_irq_work,
> + IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> + ndev->name, ndev);
> + if (ret) {
> + netdev_err(ndev, "unable to request PTP TX IRQ\n");
> + free_irq(emac->rx_irq, ndev);
> + free_irq(emac->tx_irq, ndev);

This seems somewhat asymmetric. This function does request emac->rx_irq
but not emac->tx_irq. So I don't think it is appropriate to free emac->tx_irq
here.

Also, I would suggest using a goto label for unwind here.

> + }
> + }
> +
> return ret;
> }
>

...