Re: [PATCH net-next 1/2] net: ethernet: ti: am65-cpts: Enable PTP RX HW timestamp using CPTS FIFO

[Chintan Vankar <c-vankar@ti.com>]

On 19/02/24 16:54, Roger Quadros wrote:
>
> On 15/02/2024 13:09, Chintan Vankar wrote:
>> CPTS module supports capturing timestamp for every packet it receives,
>> add a new function named "am65_cpts_rx_find_ts()" to get the timestamp
>> of received packets from CPTS FIFO.
>>
>> Add another function named "am65_cpts_rx_timestamp()" which internally
>> calls "am65_cpts_rx_find_ts()" function and timestamps the received
>> PTP packets.
>>
>> Signed-off-by: Chintan Vankar <c-vankar@ti.com>
>> ---
>>   drivers/net/ethernet/ti/am65-cpts.c | 84 +++++++++++++++++++++--------
>>   drivers/net/ethernet/ti/am65-cpts.h | 11 ++--
>>   2 files changed, 67 insertions(+), 28 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/ti/am65-cpts.c b/drivers/net/ethernet/ti/am65-cpts.c
>> index c66618d91c28..92a3b40e60d6 100644
>> --- a/drivers/net/ethernet/ti/am65-cpts.c
>> +++ b/drivers/net/ethernet/ti/am65-cpts.c
>> @@ -859,29 +859,6 @@ static long am65_cpts_ts_work(struct ptp_clock_info *ptp)
>>   	return delay;
>>   }
>>   
>> -/**
>> - * am65_cpts_rx_enable - enable rx timestamping
>> - * @cpts: cpts handle
>> - * @en: enable
>> - *
>> - * This functions enables rx packets timestamping. The CPTS can timestamp all
>> - * rx packets.
>> - */
>> -void am65_cpts_rx_enable(struct am65_cpts *cpts, bool en)
>> -{
>> -	u32 val;
>> -
>> -	mutex_lock(&cpts->ptp_clk_lock);
>> -	val = am65_cpts_read32(cpts, control);
>> -	if (en)
>> -		val |= AM65_CPTS_CONTROL_TSTAMP_EN;
>> -	else
>> -		val &= ~AM65_CPTS_CONTROL_TSTAMP_EN;
>> -	am65_cpts_write32(cpts, val, control);
>> -	mutex_unlock(&cpts->ptp_clk_lock);
>> -}
>> -EXPORT_SYMBOL_GPL(am65_cpts_rx_enable);
>> -
>>   static int am65_skb_get_mtype_seqid(struct sk_buff *skb, u32 *mtype_seqid)
>>   {
>>   	unsigned int ptp_class = ptp_classify_raw(skb);
>> @@ -906,6 +883,67 @@ static int am65_skb_get_mtype_seqid(struct sk_buff *skb, u32 *mtype_seqid)
>>   	return 1;
>>   }
>>   
>> +static u64 am65_cpts_find_rx_ts(struct am65_cpts *cpts, struct sk_buff *skb,
>> +				int ev_type, u32 skb_mtype_seqid)
>> +{
>> +	struct list_head *this, *next;
>> +	struct am65_cpts_event *event;
>> +	unsigned long flags;
>> +	u32 mtype_seqid;
>> +	u64 ns = 0;
>> +
>> +	am65_cpts_fifo_read(cpts);
> am65_cpts_fifo_read() is called from the CPTS interrupt handler and the
> event is popped out of the FIFO and pushed into an event list.
>
> Doesn't this race with that interrupt handler?
Could you clarify why there be a race condition ?
> Can't you use that event list instead of reading cpts_fifo directly?
>
> Something like am65_cpts_match_tx_ts()?
>
>> +	spin_lock_irqsave(&cpts->lock, flags);
>> +	list_for_each_safe(this, next, &cpts->events) {
>> +		event = list_entry(this, struct am65_cpts_event, list);
>> +		if (time_after(jiffies, event->tmo)) {
>> +			list_del_init(&event->list);
>> +			list_add(&event->list, &cpts->pool);
>> +			continue;
>> +		}
>> +
>> +		mtype_seqid = event->event1 &
>> +			      (AM65_CPTS_EVENT_1_MESSAGE_TYPE_MASK |
>> +			       AM65_CPTS_EVENT_1_SEQUENCE_ID_MASK |
>> +			       AM65_CPTS_EVENT_1_EVENT_TYPE_MASK);
>> +
>> +		if (mtype_seqid == skb_mtype_seqid) {
>> +			ns = event->timestamp;
>> +			list_del_init(&event->list);
>> +			list_add(&event->list, &cpts->pool);
>> +			break;
>> +		}
>> +	}
>> +	spin_unlock_irqrestore(&cpts->lock, flags);
>> +
>> +	return ns;
>> +}
>> +
>> +void am65_cpts_rx_timestamp(struct am65_cpts *cpts, struct sk_buff *skb)
>> +{
>> +	struct am65_cpts_skb_cb_data *skb_cb = (struct am65_cpts_skb_cb_data *)skb->cb;
>> +	struct skb_shared_hwtstamps *ssh;
>> +	int ret;
>> +	u64 ns;
>> +
>> +	ret = am65_skb_get_mtype_seqid(skb, &skb_cb->skb_mtype_seqid);
>> +	if (!ret)
>> +		return; /* if not PTP class packet */
>> +
>> +	skb_cb->skb_mtype_seqid |= (AM65_CPTS_EV_RX << AM65_CPTS_EVENT_1_EVENT_TYPE_SHIFT);
>> +
>> +	dev_dbg(cpts->dev, "%s mtype seqid %08x\n", __func__, skb_cb->skb_mtype_seqid);
>> +
>> +	ns = am65_cpts_find_rx_ts(cpts, skb, AM65_CPTS_EV_RX, skb_cb->skb_mtype_seqid);
>> +	if (!ns)
>> +		return;
>> +
>> +	ssh = skb_hwtstamps(skb);
>> +	memset(ssh, 0, sizeof(*ssh));
>> +	ssh->hwtstamp = ns_to_ktime(ns);
>> +}
>> +EXPORT_SYMBOL_GPL(am65_cpts_rx_timestamp);
>> +
>>   /**
>>    * am65_cpts_tx_timestamp - save tx packet for timestamping
>>    * @cpts: cpts handle
>> diff --git a/drivers/net/ethernet/ti/am65-cpts.h b/drivers/net/ethernet/ti/am65-cpts.h
>> index 6e14df0be113..6099d772799d 100644
>> --- a/drivers/net/ethernet/ti/am65-cpts.h
>> +++ b/drivers/net/ethernet/ti/am65-cpts.h
>> @@ -22,9 +22,9 @@ void am65_cpts_release(struct am65_cpts *cpts);
>>   struct am65_cpts *am65_cpts_create(struct device *dev, void __iomem *regs,
>>   				   struct device_node *node);
>>   int am65_cpts_phc_index(struct am65_cpts *cpts);
>> +void am65_cpts_rx_timestamp(struct am65_cpts *cpts, struct sk_buff *skb);
>>   void am65_cpts_tx_timestamp(struct am65_cpts *cpts, struct sk_buff *skb);
>>   void am65_cpts_prep_tx_timestamp(struct am65_cpts *cpts, struct sk_buff *skb);
>> -void am65_cpts_rx_enable(struct am65_cpts *cpts, bool en);
>>   u64 am65_cpts_ns_gettime(struct am65_cpts *cpts);
>>   int am65_cpts_estf_enable(struct am65_cpts *cpts, int idx,
>>   			  struct am65_cpts_estf_cfg *cfg);
>> @@ -48,17 +48,18 @@ static inline int am65_cpts_phc_index(struct am65_cpts *cpts)
>>   	return -1;
>>   }
>>   
>> -static inline void am65_cpts_tx_timestamp(struct am65_cpts *cpts,
>> +static inline void am65_cpts_rx_timestamp(struct am65_cpts *cpts,
>>   					  struct sk_buff *skb)
>>   {
>>   }
>>   
>> -static inline void am65_cpts_prep_tx_timestamp(struct am65_cpts *cpts,
>> -					       struct sk_buff *skb)
>> +static inline void am65_cpts_tx_timestamp(struct am65_cpts *cpts,
>> +					  struct sk_buff *skb)
>>   {
>>   }
>>   
>> -static inline void am65_cpts_rx_enable(struct am65_cpts *cpts, bool en)
>> +static inline void am65_cpts_prep_tx_timestamp(struct am65_cpts *cpts,
>> +					       struct sk_buff *skb)
>>   {
>>   }
>>