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Message-ID:
 <CO1PR11MB477123BB8AF54F351E753176E2522@CO1PR11MB4771.namprd11.prod.outlook.com>
Date: Tue, 5 Nov 2024 10:08:22 +0000
From: <Divya.Koppera@...rochip.com>
To: <vadim.fedorenko@...ux.dev>, <andrew@...n.ch>,
	<Arun.Ramadoss@...rochip.com>, <UNGLinuxDriver@...rochip.com>,
	<hkallweit1@...il.com>, <linux@...linux.org.uk>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<richardcochran@...il.com>
Subject: RE: [PATCH net-next 2/5] net: phy: microchip_ptp : Add ptp library
 for Microchip phys

Hi @Vadim Fedorenko,

Thanks for your comments.

> -----Original Message-----
> From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
> Sent: Monday, November 4, 2024 6:03 PM
> To: Divya Koppera - I30481 <Divya.Koppera@...rochip.com>;
> andrew@...n.ch; Arun Ramadoss - I17769
> <Arun.Ramadoss@...rochip.com>; UNGLinuxDriver
> <UNGLinuxDriver@...rochip.com>; hkallweit1@...il.com;
> linux@...linux.org.uk; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; pabeni@...hat.com; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; richardcochran@...il.com
> Subject: Re: [PATCH net-next 2/5] net: phy: microchip_ptp : Add ptp library for
> Microchip phys
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> On 04/11/2024 09:07, Divya Koppera wrote:
> > Add ptp library for Microchip phys
> > 1-step and 2-step modes are supported, over Ethernet and UDP(ipv4,
> > ipv6)
> >
> > Signed-off-by: Divya Koppera <divya.koppera@...rochip.com>
> > ---
> >   drivers/net/phy/microchip_ptp.c | 990
> ++++++++++++++++++++++++++++++++
> >   1 file changed, 990 insertions(+)
> >   create mode 100644 drivers/net/phy/microchip_ptp.c
> >
> > diff --git a/drivers/net/phy/microchip_ptp.c
> > b/drivers/net/phy/microchip_ptp.c new file mode 100644 index
> > 000000000000..45000984858e
> > --- /dev/null
> > +++ b/drivers/net/phy/microchip_ptp.c
> > @@ -0,0 +1,990 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright (C) 2024 Microchip Technology
> > +
> > +#include "microchip_ptp.h"
> > +
> > +static int mchp_ptp_flush_fifo(struct mchp_ptp_clock *ptp_clock,
> > +                            enum ptp_fifo_dir dir) {
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     int rc;
> > +
> > +     for (int i = 0; i < MCHP_PTP_FIFO_SIZE; ++i) {
> > +             rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                               dir == PTP_EGRESS_FIFO ?
> > +                               MCHP_PTP_TX_MSG_HEADER2(BASE_PORT(ptp_clock)) :
> > +                               MCHP_PTP_RX_MSG_HEADER2(BASE_PORT(ptp_clock)));
> > +             if (rc < 0)
> > +                     return rc;
> > +     }
> > +     return phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                         MCHP_PTP_INT_STS(BASE_PORT(ptp_clock)));
> > +}
> > +
> > +static int mchp_ptp_config_intr(struct mchp_ptp_clock *ptp_clock,
> > +                             bool enable) {
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +
> > +     /* Enable  or disable ptp interrupts */
> > +     return phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                          MCHP_PTP_INT_EN(BASE_PORT(ptp_clock)),
> > +                          enable ? MCHP_PTP_INT_ALL_MSK : 0); }
> > +
> > +static void mchp_ptp_txtstamp(struct mii_timestamper *mii_ts,
> > +                           struct sk_buff *skb, int type) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(mii_ts,
> > +                                                   struct mchp_ptp_clock,
> > +                                                   mii_ts);
> > +
> > +     switch (ptp_clock->hwts_tx_type) {
> > +     case HWTSTAMP_TX_ONESTEP_SYNC:
> > +             if (ptp_msg_is_sync(skb, type)) {
> > +                     kfree_skb(skb);
> > +                     return;
> > +             }
> > +             fallthrough;
> > +     case HWTSTAMP_TX_ON:
> > +             skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
> > +             skb_queue_tail(&ptp_clock->tx_queue, skb);
> > +             break;
> > +     case HWTSTAMP_TX_OFF:
> > +     default:
> > +             kfree_skb(skb);
> > +             break;
> > +     }
> > +}
> > +
> > +static bool mchp_ptp_get_sig_rx(struct sk_buff *skb, u16 *sig) {
> > +     struct ptp_header *ptp_header;
> > +     int type;
> > +
> > +     skb_push(skb, ETH_HLEN);
> > +     type = ptp_classify_raw(skb);
> > +     if (type == PTP_CLASS_NONE)
> > +             return false;
> > +
> > +     ptp_header = ptp_parse_header(skb, type);
> > +     if (!ptp_header)
> > +             return false;
> > +
> > +     skb_pull_inline(skb, ETH_HLEN);
> > +
> > +     *sig = ntohs(ptp_header->sequence_id);
> > +
> > +     return true;
> > +}
> > +
> > +static bool mchp_ptp_match_skb(struct mchp_ptp_clock *ptp_clock,
> > +                            struct mchp_ptp_rx_ts *rx_ts) {
> > +     struct skb_shared_hwtstamps *shhwtstamps;
> > +     struct sk_buff *skb, *skb_tmp;
> > +     unsigned long flags;
> > +     bool rc = false;
> > +     u16 skb_sig;
> > +
> > +     spin_lock_irqsave(&ptp_clock->rx_queue.lock, flags);
> > +     skb_queue_walk_safe(&ptp_clock->rx_queue, skb, skb_tmp) {
> > +             if (!mchp_ptp_get_sig_rx(skb, &skb_sig))
> > +                     continue;
> > +
> > +             if (memcmp(&skb_sig, &rx_ts->seq_id, sizeof(rx_ts->seq_id)))
> > +                     continue;
> 
> why do you use memcmp() instead of simple u16 comparison? It will be
> optimized anyway, but still, why? The same question goes to other
> comparisons futher in the file.
> 

Yes, need to simplify it. Will change in next revision at all the required places.

> > +
> > +             __skb_unlink(skb, &ptp_clock->rx_queue);
> > +
> > +             rc = true;
> > +             break;
> > +     }
> > +     spin_unlock_irqrestore(&ptp_clock->rx_queue.lock, flags);
> > +
> > +     if (rc) {
> > +             shhwtstamps = skb_hwtstamps(skb);
> > +             memset(shhwtstamps, 0, sizeof(*shhwtstamps));
> 
> I don't think this memset is needed. hwtstamp is fully overwritten on on the
> next line.
> 

I Will check on this and update.

> > +             shhwtstamps->hwtstamp = ktime_set(rx_ts->seconds, rx_ts->nsec);
> > +             netif_rx(skb);
> > +     }
> > +
> > +     return rc;
> > +}
> > +
> > +static void mchp_ptp_match_rx_ts(struct mchp_ptp_clock *ptp_clock,
> > +                              struct mchp_ptp_rx_ts *rx_ts) {
> > +     unsigned long flags;
> > +
> > +     /* If we failed to match the skb add it to the queue for when
> > +      * the frame will come
> > +      */
> > +     if (!mchp_ptp_match_skb(ptp_clock, rx_ts)) {
> > +             spin_lock_irqsave(&ptp_clock->rx_ts_lock, flags);
> > +             list_add(&rx_ts->list, &ptp_clock->rx_ts_list);
> > +             spin_unlock_irqrestore(&ptp_clock->rx_ts_lock, flags);
> > +     } else {
> > +             kfree(rx_ts);
> > +     }
> > +}
> > +
> > +static void mchp_ptp_match_rx_skb(struct mchp_ptp_clock *ptp_clock,
> > +                               struct sk_buff *skb) {
> > +     struct skb_shared_hwtstamps *shhwtstamps;
> > +     struct mchp_ptp_rx_ts *rx_ts, *tmp;
> > +     unsigned long flags;
> > +     bool match = false;
> > +     u16 skb_sig;
> > +
> > +     if (!mchp_ptp_get_sig_rx(skb, &skb_sig))
> > +             return;
> > +
> > +     /* Iterate over all RX timestamps and match it with the received skbs */
> > +     spin_lock_irqsave(&ptp_clock->rx_ts_lock, flags);
> > +     list_for_each_entry_safe(rx_ts, tmp, &ptp_clock->rx_ts_list, list) {
> > +             /* Check if we found the signature we were looking for. */
> > +             if (memcmp(&skb_sig, &rx_ts->seq_id, sizeof(rx_ts->seq_id)))
> > +                     continue;
> > +
> > +             shhwtstamps = skb_hwtstamps(skb);
> > +             memset(shhwtstamps, 0, sizeof(*shhwtstamps));
> 
> and again - memset is useless here
> 
> > +             shhwtstamps->hwtstamp = ktime_set(rx_ts->seconds,
> > +                                               rx_ts->nsec);
> > +             netif_rx(skb);
> > +
> > +             list_del(&rx_ts->list);
> > +             kfree(rx_ts);
> 
> kfree can be done outside of spinlock as well as all other timestamp
> manipulations to reduce spinlock scope.

Ok. Will change.

> > +
> > +             match = true;
> > +             break;
> > +     }
> > +     spin_unlock_irqrestore(&ptp_clock->rx_ts_lock, flags);
> 
> it's a good idea to think about RCU implementaton of the ts list as this
> spinlock may become pretty hot on high packet rate.
> 

I'm new to this RCU, at present will continue using this. Will take care in further new developments.

> > +
> > +     if (!match)
> > +             skb_queue_tail(&ptp_clock->rx_queue, skb); }
> > +
> > +static bool mchp_ptp_rxtstamp(struct mii_timestamper *mii_ts,
> > +                           struct sk_buff *skb, int type) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(mii_ts,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     mii_ts);
> > +
> > +     if (ptp_clock->rx_filter == HWTSTAMP_FILTER_NONE ||
> > +         type == PTP_CLASS_NONE)
> > +             return false;
> > +
> > +     if ((type & ptp_clock->version) == 0 || (type & ptp_clock->layer) == 0)
> > +             return false;
> > +
> > +     /* Here if match occurs skb is sent to application, If not skb is added
> > +      * to queue and sending skb to application will get handled when
> > +      * interrupt occurs i.e., it get handles in interrupt handler. By
> > +      * any means skb will reach the application so we should not return
> > +      * false here if skb doesn't matches.
> > +      */
> > +     mchp_ptp_match_rx_skb(ptp_clock, skb);
> > +
> > +     return true;
> > +}
> > +
> > +static int mchp_ptp_hwtstamp(struct mii_timestamper *mii_ts,
> > +                          struct kernel_hwtstamp_config *config,
> > +                          struct netlink_ext_ack *extack) {
> > +     struct mchp_ptp_clock *ptp_clock =
> > +                             container_of(mii_ts, struct mchp_ptp_clock,
> > +                                          mii_ts);
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     struct mchp_ptp_rx_ts *rx_ts, *tmp;
> > +     int txcfg = 0, rxcfg = 0;
> > +     int rc;
> > +
> > +     ptp_clock->hwts_tx_type = config->tx_type;
> > +     ptp_clock->rx_filter = config->rx_filter;
> > +
> > +     switch (config->rx_filter) {
> > +     case HWTSTAMP_FILTER_NONE:
> > +             ptp_clock->layer = 0;
> > +             ptp_clock->version = 0;
> > +             break;
> > +     case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
> > +     case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
> > +     case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ:
> > +             ptp_clock->layer = PTP_CLASS_L4;
> > +             ptp_clock->version = PTP_CLASS_V2;
> > +             break;
> > +     case HWTSTAMP_FILTER_PTP_V2_L2_EVENT:
> > +     case HWTSTAMP_FILTER_PTP_V2_L2_SYNC:
> > +     case HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ:
> > +             ptp_clock->layer = PTP_CLASS_L2;
> > +             ptp_clock->version = PTP_CLASS_V2;
> > +             break;
> > +     case HWTSTAMP_FILTER_PTP_V2_EVENT:
> > +     case HWTSTAMP_FILTER_PTP_V2_SYNC:
> > +     case HWTSTAMP_FILTER_PTP_V2_DELAY_REQ:
> > +             ptp_clock->layer = PTP_CLASS_L4 | PTP_CLASS_L2;
> > +             ptp_clock->version = PTP_CLASS_V2;
> > +             break;
> > +     default:
> > +             return -ERANGE;
> > +     }
> > +
> > +     /* Setup parsing of the frames and enable the timestamping for ptp
> > +      * frames
> > +      */
> > +     if (ptp_clock->layer & PTP_CLASS_L2) {
> > +             rxcfg = MCHP_PTP_PARSE_CONFIG_LAYER2_EN;
> > +             txcfg = MCHP_PTP_PARSE_CONFIG_LAYER2_EN;
> > +     }
> > +     if (ptp_clock->layer & PTP_CLASS_L4) {
> > +             rxcfg |= MCHP_PTP_PARSE_CONFIG_IPV4_EN |
> > +                      MCHP_PTP_PARSE_CONFIG_IPV6_EN;
> > +             txcfg |= MCHP_PTP_PARSE_CONFIG_IPV4_EN |
> > +                      MCHP_PTP_PARSE_CONFIG_IPV6_EN;
> > +     }
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_RX_PARSE_CONFIG(BASE_PORT(ptp_clock)),
> > +                        rxcfg);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_TX_PARSE_CONFIG(BASE_PORT(ptp_clock)),
> > +                        txcfg);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_RX_TIMESTAMP_EN(BASE_PORT(ptp_clock)),
> > +                        MCHP_PTP_TIMESTAMP_EN_ALL);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_TX_TIMESTAMP_EN(BASE_PORT(ptp_clock)),
> > +                        MCHP_PTP_TIMESTAMP_EN_ALL);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     if (ptp_clock->hwts_tx_type == HWTSTAMP_TX_ONESTEP_SYNC)
> > +             /* Enable / disable of the TX timestamp in the SYNC frames */
> > +             rc = phy_modify_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                 MCHP_PTP_TX_MOD(BASE_PORT(ptp_clock)),
> > +                                 MCHP_PTP_TX_MOD_PTP_SYNC_TS_INSERT,
> > +                                 MCHP_PTP_TX_MOD_PTP_SYNC_TS_INSERT);
> > +     else
> > +             rc = phy_modify_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                 MCHP_PTP_TX_MOD(BASE_PORT(ptp_clock)),
> > +                                 MCHP_PTP_TX_MOD_PTP_SYNC_TS_INSERT,
> > +
> > + (u16)~MCHP_PTP_TX_MOD_PTP_SYNC_TS_INSERT);
> > +
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     /* Now enable the timestamping interrupts */
> > +     rc = mchp_ptp_config_intr(ptp_clock,
> > +                               config->rx_filter != HWTSTAMP_FILTER_NONE);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     /* In case of multiple starts and stops, these needs to be cleared */
> > +     list_for_each_entry_safe(rx_ts, tmp, &ptp_clock->rx_ts_list, list) {
> > +             list_del(&rx_ts->list);
> > +             kfree(rx_ts);
> > +     }
> 
> I think this list clearing should be done under spinlock too.
> 

Yes, will update.

> > +     skb_queue_purge(&ptp_clock->rx_queue);
> > +     skb_queue_purge(&ptp_clock->tx_queue);
> > +
> > +     rc = mchp_ptp_flush_fifo(ptp_clock, PTP_INGRESS_FIFO);
> > +     if (rc < 0)
> > +             return rc;
> > +
> > +     rc = mchp_ptp_flush_fifo(ptp_clock, PTP_EGRESS_FIFO);
> > +
> > +     return rc < 0 ? rc : 0;
> > +}
> > +
> > +static int mchp_ptp_ts_info(struct mii_timestamper *mii_ts,
> > +                         struct kernel_ethtool_ts_info *info) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(mii_ts,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     mii_ts);
> > +
> > +     info->phc_index =
> > +             ptp_clock->ptp_clock ? ptp_clock_index(ptp_clock->ptp_clock) : -1;
> > +     if (info->phc_index == -1)
> > +             return 0;
> > +
> > +     info->so_timestamping = SOF_TIMESTAMPING_TX_HARDWARE |
> > +                             SOF_TIMESTAMPING_RX_HARDWARE |
> > +                             SOF_TIMESTAMPING_RAW_HARDWARE;
> > +
> > +     info->tx_types = BIT(HWTSTAMP_TX_OFF) | BIT(HWTSTAMP_TX_ON) |
> > +                      BIT(HWTSTAMP_TX_ONESTEP_SYNC);
> > +
> > +     info->rx_filters = BIT(HWTSTAMP_FILTER_NONE) |
> > +                        BIT(HWTSTAMP_FILTER_PTP_V2_L4_EVENT) |
> > +                        BIT(HWTSTAMP_FILTER_PTP_V2_L2_EVENT) |
> > +                        BIT(HWTSTAMP_FILTER_PTP_V2_EVENT);
> > +
> > +     return 0;
> > +}
> > +
> > +static int mchp_ptp_ltc_adjtime(struct ptp_clock_info *info, s64
> > +delta) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(info,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     caps);
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     struct timespec64 ts;
> > +     bool add = true;
> > +     int rc = 0;
> > +     u32 nsec;
> > +     s32 sec;
> > +
> > +     /* The HW allows up to 15 sec to adjust the time, but here we limit to
> > +      * 10 sec the adjustment. The reason is, in case the adjustment is 14
> > +      * sec and 999999999 nsec, then we add 8ns to compensate the actual
> > +      * increment so the value can be bigger than 15 sec. Therefore limit the
> > +      * possible adjustments so we will not have these corner cases
> > +      */
> > +     if (delta > 10000000000LL || delta < -10000000000LL) {
> > +             /* The timeadjustment is too big, so fall back using set time */
> > +             u64 now;
> > +
> > +             info->gettime64(info, &ts);
> > +
> > +             now = ktime_to_ns(timespec64_to_ktime(ts));
> > +             ts = ns_to_timespec64(now + delta);
> > +
> > +             info->settime64(info, &ts);
> > +             return 0;
> > +     }
> > +     sec = div_u64_rem(abs(delta), NSEC_PER_SEC, &nsec);
> > +     if (delta < 0 && nsec != 0) {
> > +             /* It is not allowed to adjust low the nsec part, therefore
> > +              * subtract more from second part and add to nanosecond such
> > +              * that would roll over, so the second part will increase
> > +              */
> > +             sec--;
> > +             nsec = NSEC_PER_SEC - nsec;
> > +     }
> > +
> > +     /* Calculate the adjustments and the direction */
> > +     if (delta < 0)
> > +             add = false;
> > +
> > +     if (nsec > 0) {
> > +             /* add 8 ns to cover the likely normal increment */
> > +             nsec += 8;
> > +
> > +             if (nsec >= NSEC_PER_SEC) {
> > +                     /* carry into seconds */
> > +                     sec++;
> > +                     nsec -= NSEC_PER_SEC;
> > +             }
> > +     }
> > +
> > +     mutex_lock(&ptp_clock->ptp_lock);
> > +     if (sec) {
> > +             sec = abs(sec);
> > +
> > +             rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                MCHP_PTP_LTC_STEP_ADJ_LO(BASE_CLK(ptp_clock)),
> > +                                sec);
> > +             if (rc < 0)
> > +                     goto out_unlock;
> > +             rc = phy_set_bits_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                   MCHP_PTP_LTC_STEP_ADJ_HI(BASE_CLK(ptp_clock)),
> > +                                   ((add ? MCHP_PTP_LTC_STEP_ADJ_HI_DIR :
> > +                                     0) | ((sec >> 16) & GENMASK(13, 0))));
> > +             if (rc < 0)
> > +                     goto out_unlock;
> > +             rc = phy_set_bits_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                   MCHP_PTP_CMD_CTL(BASE_CLK(ptp_clock)),
> > +                                   MCHP_PTP_CMD_CTL_LTC_STEP_SEC);
> > +             if (rc < 0)
> > +                     goto out_unlock;
> > +     }
> > +
> > +     if (nsec) {
> > +             rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                MCHP_PTP_LTC_STEP_ADJ_LO(BASE_CLK(ptp_clock)),
> > +                                nsec & GENMASK(15, 0));
> > +             if (rc < 0)
> > +                     goto out_unlock;
> > +             rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                MCHP_PTP_LTC_STEP_ADJ_HI(BASE_CLK(ptp_clock)),
> > +                                (nsec >> 16) & GENMASK(13, 0));
> > +             if (rc < 0)
> > +                     goto out_unlock;
> > +             rc = phy_set_bits_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                   MCHP_PTP_CMD_CTL(BASE_CLK(ptp_clock)),
> > +                                   MCHP_PTP_CMD_CTL_LTC_STEP_NSEC);
> > +     }
> > +
> > +out_unlock:
> > +     mutex_unlock(&ptp_clock->ptp_lock);
> > +
> > +     return rc;
> > +}
> > +
> > +static int mchp_ptp_ltc_adjfine(struct ptp_clock_info *info, long
> > +scaled_ppm) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(info,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     caps);
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     u16 rate_lo, rate_hi;
> > +     bool faster = true;
> > +     u32 rate;
> > +     int rc;
> > +
> > +     if (!scaled_ppm)
> > +             return 0;
> > +
> > +     if (scaled_ppm < 0) {
> > +             scaled_ppm = -scaled_ppm;
> > +             faster = false;
> > +     }
> > +
> > +     rate = MCHP_PTP_1PPM_FORMAT * (upper_16_bits(scaled_ppm));
> > +     rate += (MCHP_PTP_1PPM_FORMAT * (lower_16_bits(scaled_ppm))) >>
> > + 16;
> > +
> > +     rate_lo = rate & GENMASK(15, 0);
> > +     rate_hi = (rate >> 16) & GENMASK(13, 0);
> > +
> > +     if (faster)
> > +             rate_hi |= MCHP_PTP_LTC_RATE_ADJ_HI_DIR;
> > +
> > +     mutex_lock(&ptp_clock->ptp_lock);
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_RATE_ADJ_HI(BASE_CLK(ptp_clock)),
> > +                        rate_hi);
> > +     if (rc < 0)
> > +             goto error;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_RATE_ADJ_LO(BASE_CLK(ptp_clock)),
> > +                        rate_lo);
> > +     if (rc > 0)
> > +             rc = 0;
> > +error:
> > +     mutex_unlock(&ptp_clock->ptp_lock);
> > +
> > +     return rc;
> > +}
> > +
> > +static int mchp_ptp_ltc_gettime64(struct ptp_clock_info *info,
> > +                               struct timespec64 *ts) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(info,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     caps);
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     time64_t secs;
> > +     int rc = 0;
> > +     s64 nsecs;
> > +
> > +     mutex_lock(&ptp_clock->ptp_lock);
> > +     /* Set read bit to 1 to save current values of 1588 local time counter
> > +      * into PTP LTC seconds and nanoseconds registers.
> > +      */
> > +     rc = phy_set_bits_mmd(phydev, PTP_MMD(ptp_clock),
> > +                           MCHP_PTP_CMD_CTL(BASE_CLK(ptp_clock)),
> > +                           MCHP_PTP_CMD_CTL_CLOCK_READ);
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     /* Get LTC clock values */
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_LTC_READ_SEC_HI(BASE_CLK(ptp_clock)));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +     secs = rc << 16;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_LTC_READ_SEC_MID(BASE_CLK(ptp_clock)));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +     secs |= rc;
> > +     secs <<= 16;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_LTC_READ_SEC_LO(BASE_CLK(ptp_clock)));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +     secs |= rc;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_LTC_READ_NS_HI(BASE_CLK(ptp_clock)));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +     nsecs = (rc & GENMASK(13, 0));
> > +     nsecs <<= 16;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_LTC_READ_NS_LO(BASE_CLK(ptp_clock)));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +     nsecs |= rc;
> > +
> > +     set_normalized_timespec64(ts, secs, nsecs);
> > +
> > +     if (rc > 0)
> > +             rc = 0;
> > +out_unlock:
> > +     mutex_unlock(&ptp_clock->ptp_lock);
> 
> That's interesting, but could the overwrapping happen to seconds counter
> while reading nanoseconds? Usually high bits reading is wrapped into
> while() loop to advoid such cases.
> 

We are reading the static values that are written in register at particular time when read bit is set.
Nsecs will not be more than 1000000000, which further will not increment or decrement secs.
So overwrapping to seconds counter while reading nanoseconds will not happen. 

Safer way we can assign the values directly.

> > +
> > +     return rc;
> > +}
> > +
> > +static int mchp_ptp_ltc_settime64(struct ptp_clock_info *info,
> > +                               const struct timespec64 *ts) {
> > +     struct mchp_ptp_clock *ptp_clock = container_of(info,
> > +                                                     struct mchp_ptp_clock,
> > +                                                     caps);
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     int rc;
> > +
> > +     mutex_lock(&ptp_clock->ptp_lock);
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_SEC_LO(BASE_CLK(ptp_clock)),
> > +                        lower_16_bits(ts->tv_sec));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_SEC_MID(BASE_CLK(ptp_clock)),
> > +                        upper_16_bits(ts->tv_sec));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_SEC_HI(BASE_CLK(ptp_clock)),
> > +                        upper_32_bits(ts->tv_sec) & GENMASK(15, 0));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_NS_LO(BASE_CLK(ptp_clock)),
> > +                        lower_16_bits(ts->tv_nsec));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     rc = phy_write_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_LTC_NS_HI(BASE_CLK(ptp_clock)),
> > +                        upper_16_bits(ts->tv_nsec) & GENMASK(13, 0));
> > +     if (rc < 0)
> > +             goto out_unlock;
> > +
> > +     /* Set load bit to 1 to write PTP LTC seconds and nanoseconds
> > +      * registers to 1588 local time counter.
> > +      */
> > +     rc = phy_set_bits_mmd(phydev, PTP_MMD(ptp_clock),
> > +                           MCHP_PTP_CMD_CTL(BASE_CLK(ptp_clock)),
> > +                           MCHP_PTP_CMD_CTL_CLOCK_LOAD);
> > +     if (rc > 0)
> > +             rc = 0;
> > +out_unlock:
> > +     mutex_unlock(&ptp_clock->ptp_lock);
> > +
> > +     return rc;
> > +}
> > +
> > +static bool mchp_ptp_get_sig_tx(struct sk_buff *skb, u16 *sig) {
> > +     struct ptp_header *ptp_header;
> > +     int type;
> > +
> > +     type = ptp_classify_raw(skb);
> > +     if (type == PTP_CLASS_NONE)
> > +             return false;
> > +
> > +     ptp_header = ptp_parse_header(skb, type);
> > +     if (!ptp_header)
> > +             return false;
> > +
> > +     *sig = htons(ptp_header->sequence_id);
> > +
> > +     return true;
> > +}
> > +
> > +static void mchp_ptp_match_tx_skb(struct mchp_ptp_clock *ptp_clock,
> > +                               u32 seconds, u32 nsec, u16 seq_id) {
> > +     struct skb_shared_hwtstamps shhwtstamps;
> > +     struct sk_buff *skb, *skb_tmp;
> > +     unsigned long flags;
> > +     bool rc = false;
> > +     u16 skb_sig;
> > +
> > +     spin_lock_irqsave(&ptp_clock->tx_queue.lock, flags);
> > +     skb_queue_walk_safe(&ptp_clock->tx_queue, skb, skb_tmp) {
> > +             if (!mchp_ptp_get_sig_tx(skb, &skb_sig))
> > +                     continue;
> > +
> > +             if (memcmp(&skb_sig, &seq_id, sizeof(seq_id)))
> > +                     continue;
> > +
> > +             __skb_unlink(skb, &ptp_clock->tx_queue);
> > +             rc = true;
> > +             break;
> > +     }
> > +     spin_unlock_irqrestore(&ptp_clock->tx_queue.lock, flags);
> > +
> > +     if (rc) {
> > +             memset(&shhwtstamps, 0, sizeof(shhwtstamps));
> > +             shhwtstamps.hwtstamp = ktime_set(seconds, nsec);
> > +             skb_complete_tx_timestamp(skb, &shhwtstamps);
> > +     }
> > +}
> > +
> > +static struct mchp_ptp_rx_ts *mchp_ptp_get_rx_ts(struct
> > +mchp_ptp_clock *ptp_clock) {
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     struct mchp_ptp_rx_ts *rx_ts = NULL;
> > +     u32 sec, nsec;
> > +     u16 seq;
> > +     int rc;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_RX_INGRESS_NS_HI(BASE_PORT(ptp_clock)));
> > +     if (rc < 0)
> > +             goto error;
> > +     if (!(rc & MCHP_PTP_RX_INGRESS_NS_HI_TS_VALID)) {
> > +             phydev_err(phydev, "RX Timestamp is not valid!\n");
> > +             goto error;
> > +     }
> > +     nsec = (rc & GENMASK(13, 0)) << 16;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_RX_INGRESS_NS_LO(BASE_PORT(ptp_clock)));
> > +     if (rc < 0)
> > +             goto error;
> > +     nsec |= rc;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_RX_INGRESS_SEC_HI(BASE_PORT(ptp_clock)));
> > +     if (rc < 0)
> > +             goto error;
> > +     sec = rc << 16;
> > +
> > +     rc = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                       MCHP_PTP_RX_INGRESS_SEC_LO(BASE_PORT(ptp_clock)));
> > +     if (rc < 0)
> > +             goto error;
> > +     sec |= rc;
> > +
> > +     seq = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                        MCHP_PTP_RX_MSG_HEADER2(BASE_PORT(ptp_clock)));
> > +     if (seq < 0)
> > +             goto error;
> > +
> > +     rx_ts = kzalloc(sizeof(*rx_ts), GFP_KERNEL);
> 
> why zero out allocation? all fields of this structure are rewritten
> unconditionally later (list_add happens in mchp_ptp_match_rx_ts) ...
> 

I will recheck and update this.

> > +     if (!rx_ts)
> > +             return NULL;
> > +
> > +     rx_ts->seconds = sec;
> > +     rx_ts->nsec = nsec;
> > +     rx_ts->seq_id = seq;
> > +
> > +error:
> > +     return rx_ts;
> > +}
> > +
> > +static void mchp_ptp_process_rx_ts(struct mchp_ptp_clock *ptp_clock)
> > +{
> > +     struct phy_device *phydev = ptp_clock->phydev;
> > +     int caps;
> > +
> > +     do {
> > +             struct mchp_ptp_rx_ts *rx_ts;
> > +
> > +             rx_ts = mchp_ptp_get_rx_ts(ptp_clock);
> > +             if (rx_ts)
> > +                     mchp_ptp_match_rx_ts(ptp_clock, rx_ts);
> > +
> > +             caps = phy_read_mmd(phydev, PTP_MMD(ptp_clock),
> > +                                 MCHP_PTP_CAP_INFO(BASE_PORT(ptp_clock)));
> > +             if (caps < 0)
> > +                     return;
> > +     } while (MCHP_PTP_RX_TS_CNT(caps) > 0); }
> > +
> 
> [ ... ]

Thanks,
Divya

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