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igc: Add support for DMA timestamp for non-PTP packets
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For PTP traffic, timestamp is retrieved from TXSTMP register.
For all other packets, DMA timestamp field of the Transmit
Descriptor Write-back is used.

This is required to work around the HW time stamp misses in
TXSTAMP register due to the HW limitation, when heavy traffic
is initiated.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
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@vcgomes @ranjan-dutta
vcgomes authored and ranjan-dutta committed May 24, 2021
1 parent b0c88db commit 26a890b
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Showing 5 changed files with 100 additions and 2 deletions.
4 changes: 4 additions & 0 deletions drivers/net/ethernet/intel/igc/igc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -418,6 +418,8 @@ enum igc_tx_flags {
/* olinfo flags */
IGC_TX_FLAGS_IPV4 = 0x10,
IGC_TX_FLAGS_CSUM = 0x20,

IGC_TX_FLAGS_DMA_TSTAMP = 0x200,
};

enum igc_boards {
Expand Down Expand Up @@ -613,6 +615,8 @@ void igc_ptp_reset(struct igc_adapter *adapter);
void igc_ptp_suspend(struct igc_adapter *adapter);
void igc_ptp_stop(struct igc_adapter *adapter);
ktime_t igc_ptp_rx_pktstamp(struct igc_adapter *adapter, __le32 *buf);
void igc_ptp_tx_dma_tstamp(struct igc_adapter *adapter,
struct sk_buff *skb, u64 tstamp);
int igc_ptp_set_ts_config(struct net_device *netdev, struct ifreq *ifr);
int igc_ptp_get_ts_config(struct net_device *netdev, struct ifreq *ifr);
void igc_ptp_tx_hang(struct igc_adapter *adapter);
Expand Down
2 changes: 1 addition & 1 deletion drivers/net/ethernet/intel/igc/igc_base.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ union igc_adv_tx_desc {
__le32 olinfo_status;
} read;
struct {
__le64 rsvd; /* Reserved */
__le64 dma_tstamp;
__le32 nxtseq_seed;
__le32 status;
} wb;
Expand Down
2 changes: 2 additions & 0 deletions drivers/net/ethernet/intel/igc/igc_defines.h
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Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,7 @@
#define IGC_TXD_CMD_DEXT 0x20000000 /* Desc extension (0 = legacy) */
#define IGC_TXD_CMD_VLE 0x40000000 /* Add VLAN tag */
#define IGC_TXD_STAT_DD 0x00000001 /* Descriptor Done */
#define IGC_TXD_STAT_TS_STAT 0x00000002 /* DMA Timestamp in packet */
#define IGC_TXD_CMD_TCP 0x01000000 /* TCP packet */
#define IGC_TXD_CMD_IP 0x02000000 /* IP packet */
#define IGC_TXD_CMD_TSE 0x04000000 /* TCP Seg enable */
Expand Down Expand Up @@ -478,6 +479,7 @@
#define IGC_TQAVCTRL_TRANSMIT_MODE_TSN 0x00000001
#define IGC_TQAVCTRL_ENHANCED_QAV 0x00000008
#define IGC_TQAVCTRL_PREEMPT_ENA 0x00000002
#define IGC_TQAVCTRL_1588_STAT_EN 0x00000004
#define IGC_TQAVCTRL_MIN_FRAG_MASK 0x0000C000
#define IGC_TQAVCTRL_MIN_FRAG_SHIFT 14

Expand Down
22 changes: 21 additions & 1 deletion drivers/net/ethernet/intel/igc/igc_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1412,6 +1412,14 @@ static int igc_tso(struct igc_ring *tx_ring,
return 1;
}

static bool igc_is_ptp_packet(struct sk_buff *skb)
{
__be16 protocol = vlan_get_protocol(skb);

/* FIXME: also handle UDP packets */
return protocol == htons(ETH_P_1588);
}

static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
struct igc_ring *tx_ring)
{
Expand Down Expand Up @@ -1447,6 +1455,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,

if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
struct igc_adapter *adapter = netdev_priv(tx_ring->netdev);
bool is_ptp = igc_is_ptp_packet(skb);

spin_lock(&adapter->ptp_tx_lock);

Expand All @@ -1455,12 +1464,16 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
* timestamping request.
*/
if (adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON &&
!adapter->ptp_tx_skb) {
is_ptp && !adapter->ptp_tx_skb) {
skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
tx_flags |= IGC_TX_FLAGS_TSTAMP;

adapter->ptp_tx_skb = skb_get(skb);
adapter->ptp_tx_start = jiffies;
} else if (adapter->tstamp_config.tx_type == HWTSTAMP_TX_ON &&
!is_ptp) {
skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
tx_flags |= IGC_TX_FLAGS_DMA_TSTAMP;
} else {
adapter->tx_hwtstamp_skipped++;
}
Expand Down Expand Up @@ -2693,6 +2706,13 @@ static bool igc_clean_tx_irq(struct igc_q_vector *q_vector, int napi_budget)
if (!(eop_desc->wb.status & cpu_to_le32(IGC_TXD_STAT_DD)))
break;

if (eop_desc->wb.status & cpu_to_le32(IGC_TXD_STAT_TS_STAT) &&
tx_buffer->tx_flags & IGC_TX_FLAGS_DMA_TSTAMP) {
u64 tstamp = le64_to_cpu(eop_desc->wb.dma_tstamp);

igc_ptp_tx_dma_tstamp(adapter, tx_buffer->skb, tstamp);
}

/* clear next_to_watch to prevent false hangs */
tx_buffer->next_to_watch = NULL;

Expand Down
72 changes: 72 additions & 0 deletions drivers/net/ethernet/intel/igc/igc_ptp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,31 @@ static void igc_ptp_systim_to_hwtstamp(struct igc_adapter *adapter,
}
}

static void igc_ptp_dma_time_to_hwtstamp(struct igc_adapter *adapter,
struct skb_shared_hwtstamps *hwtstamps,
u64 systim)
{
struct igc_hw *hw = &adapter->hw;
u32 sec, nsec;

/* FIXME: use a workqueue to read these values to avoid
* reading these registers in the hot path.
*/
nsec = rd32(IGC_SYSTIML);
sec = rd32(IGC_SYSTIMH);

switch (adapter->hw.mac.type) {
case igc_i225:
memset(hwtstamps, 0, sizeof(*hwtstamps));

/* HACK */
hwtstamps->hwtstamp = ktime_set(sec, systim & 0xFFFFFFFF);
break;
default:
break;
}
}

/**
* igc_ptp_rx_pktstamp - Retrieve timestamp from Rx packet buffer
* @adapter: Pointer to adapter the packet buffer belongs to
Expand Down Expand Up @@ -532,13 +557,26 @@ static void igc_ptp_enable_rx_timestamp(struct igc_adapter *adapter)
static void igc_ptp_disable_tx_timestamp(struct igc_adapter *adapter)
{
struct igc_hw *hw = &adapter->hw;
u32 tqavctrl;

tqavctrl = rd32(IGC_TQAVCTRL);
tqavctrl &= ~IGC_TQAVCTRL_1588_STAT_EN;

wr32(IGC_TQAVCTRL, tqavctrl);

wr32(IGC_TSYNCTXCTL, 0);
}

static void igc_ptp_enable_tx_timestamp(struct igc_adapter *adapter)
{
struct igc_hw *hw = &adapter->hw;
u32 tqavctrl;

/* Enable DMA Fetch timestamping */
tqavctrl = rd32(IGC_TQAVCTRL);
tqavctrl |= IGC_TQAVCTRL_1588_STAT_EN;

wr32(IGC_TQAVCTRL, tqavctrl);

wr32(IGC_TSYNCTXCTL, IGC_TSYNCTXCTL_ENABLED | IGC_TSYNCTXCTL_TXSYNSIG);

Expand Down Expand Up @@ -687,6 +725,40 @@ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter)
dev_kfree_skb_any(skb);
}

void igc_ptp_tx_dma_tstamp(struct igc_adapter *adapter,
struct sk_buff *skb, u64 tstamp)
{
struct skb_shared_hwtstamps shhwtstamps;
int adjust = 0;

if (!(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
return;

igc_ptp_dma_time_to_hwtstamp(adapter, &shhwtstamps, tstamp);

/* FIXME: Use different latencies for DMA timestamps? */
switch (adapter->link_speed) {
case SPEED_10:
adjust = IGC_I225_TX_LATENCY_10;
break;
case SPEED_100:
adjust = IGC_I225_TX_LATENCY_100;
break;
case SPEED_1000:
adjust = IGC_I225_TX_LATENCY_1000;
break;
case SPEED_2500:
adjust = IGC_I225_TX_LATENCY_2500;
break;
}

shhwtstamps.hwtstamp =
ktime_add_ns(shhwtstamps.hwtstamp, adjust);

/* Notify the stack and free the skb after we've unlocked */
skb_tstamp_tx(skb, &shhwtstamps);
}

/**
* igc_ptp_tx_work
* @work: pointer to work struct
Expand Down

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