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Message-ID: <52B6E568.4030400@mellanox.com>
Date: Sun, 22 Dec 2013 15:13:12 +0200
From: Hadar Hen Zion <hadarh@...lanox.com>
To: Shawn Bohrer <shawn.bohrer@...il.com>
CC: "David S. Miller" <davem@...emloft.net>,
Or Gerlitz <ogerlitz@...lanox.com>,
Amir Vadai <amirv@...lanox.com>,
Richard Cochran <richardcochran@...il.com>,
<netdev@...r.kernel.org>, <tomk@...advisors.com>,
Shawn Bohrer <sbohrer@...advisors.com>
Subject: Re: [PATCH net-next 1/2] mlx4_en: Add PTP hardware clock
On 12/17/2013 10:32 PM, Shawn Bohrer wrote:
> From: Shawn Bohrer <sbohrer@...advisors.com>
>
> This adds a PHC to the mlx4_en driver. The code is largely based off of
> the e1000e driver (drivers/net/ethernet/intel/e1000e/ptp.c) which seemed
> very similar.
>
> This driver has been tested with both Documentation/ptp/testptp and the
> linuxptp project (http://linuxptp.sourceforge.net/) and appears to work
> on a Mellanox ConnectX-3 card.
>
> Signed-off-by: Shawn Bohrer <sbohrer@...advisors.com>
> ---
> drivers/net/ethernet/mellanox/mlx4/en_clock.c | 192 ++++++++++++++++++++++-
> drivers/net/ethernet/mellanox/mlx4/en_ethtool.c | 3 +
> drivers/net/ethernet/mellanox/mlx4/en_main.c | 3 +
> drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 6 +
> 4 files changed, 196 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> index fd64410..9b0d515 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> @@ -103,17 +103,187 @@ void mlx4_en_fill_hwtstamps(struct mlx4_en_dev *mdev,
> struct skb_shared_hwtstamps *hwts,
> u64 timestamp)
> {
> + unsigned long flags;
> u64 nsec;
>
> + spin_lock_irqsave(&mdev->clock_lock, flags);
1. Missing initialization for clock_lock
2. Adding spin lock in the data path reduce performance by 15% when HW
timestamping is enabled. I did some testing and replacing
spin_lock_irqsave with read/write_lock_irqsave prevents the performance
decrease.
Thanks,
Hadar
> nsec = timecounter_cyc2time(&mdev->clock, timestamp);
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
>
> memset(hwts, 0, sizeof(struct skb_shared_hwtstamps));
> hwts->hwtstamp = ns_to_ktime(nsec);
> }
>
> +/**
> + * mlx4_en_remove_timestamp - disable PTP device
> + * @mdev: board private structure
> + *
> + * Stop the PTP support.
> + **/
> +void mlx4_en_remove_timestamp(struct mlx4_en_dev *mdev)
> +{
> + if (mdev->ptp_clock) {
> + ptp_clock_unregister(mdev->ptp_clock);
> + mdev->ptp_clock = NULL;
> + mlx4_info(mdev, "removed PHC\n");
> + }
> +}
> +
> +void mlx4_en_ptp_overflow_check(struct mlx4_en_dev *mdev)
> +{
> + bool timeout = time_is_before_jiffies(mdev->last_overflow_check +
> + mdev->overflow_period);
> + unsigned long flags;
> +
> + if (timeout) {
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> + timecounter_read(&mdev->clock);
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
> + mdev->last_overflow_check = jiffies;
> + }
> +}
> +
> +/**
> + * mlx4_en_phc_adjfreq - adjust the frequency of the hardware clock
> + * @ptp: ptp clock structure
> + * @delta: Desired frequency change in parts per billion
> + *
> + * Adjust the frequency of the PHC cycle counter by the indicated delta from
> + * the base frequency.
> + **/
> +static int mlx4_en_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
> +{
> + u64 adj;
> + u32 diff, mult;
> + int neg_adj = 0;
> + unsigned long flags;
> + struct mlx4_en_dev *mdev = container_of(ptp, struct mlx4_en_dev,
> + ptp_clock_info);
> +
> + if (delta < 0) {
> + neg_adj = 1;
> + delta = -delta;
> + }
> + mult = mdev->nominal_c_mult;
> + adj = mult;
> + adj *= delta;
> + diff = div_u64(adj, 1000000000ULL);
> +
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> + timecounter_read(&mdev->clock);
> + mdev->cycles.mult = neg_adj ? mult - diff : mult + diff;
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
> +
> + return 0;
> +}
> +
> +/**
> + * mlx4_en_phc_adjtime - Shift the time of the hardware clock
> + * @ptp: ptp clock structure
> + * @delta: Desired change in nanoseconds
> + *
> + * Adjust the timer by resetting the timecounter structure.
> + **/
> +static int mlx4_en_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
> +{
> + struct mlx4_en_dev *mdev = container_of(ptp, struct mlx4_en_dev,
> + ptp_clock_info);
> + unsigned long flags;
> + s64 now;
> +
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> + now = timecounter_read(&mdev->clock);
> + now += delta;
> + timecounter_init(&mdev->clock, &mdev->cycles, now);
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
> +
> + return 0;
> +}
> +
> +/**
> + * mlx4_en_phc_gettime - Reads the current time from the hardware clock
> + * @ptp: ptp clock structure
> + * @ts: timespec structure to hold the current time value
> + *
> + * Read the timecounter and return the correct value in ns after converting
> + * it into a struct timespec.
> + **/
> +static int mlx4_en_phc_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
> +{
> + struct mlx4_en_dev *mdev = container_of(ptp, struct mlx4_en_dev,
> + ptp_clock_info);
> + unsigned long flags;
> + u32 remainder;
> + u64 ns;
> +
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> + ns = timecounter_read(&mdev->clock);
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
> +
> + ts->tv_sec = div_u64_rem(ns, NSEC_PER_SEC, &remainder);
> + ts->tv_nsec = remainder;
> +
> + return 0;
> +}
> +
> +/**
> + * mlx4_en_phc_settime - Set the current time on the hardware clock
> + * @ptp: ptp clock structure
> + * @ts: timespec containing the new time for the cycle counter
> + *
> + * Reset the timecounter to use a new base value instead of the kernel
> + * wall timer value.
> + **/
> +static int mlx4_en_phc_settime(struct ptp_clock_info *ptp,
> + const struct timespec *ts)
> +{
> + struct mlx4_en_dev *mdev = container_of(ptp, struct mlx4_en_dev,
> + ptp_clock_info);
> + u64 ns = timespec_to_ns(ts);
> + unsigned long flags;
> +
> + /* reset the timecounter */
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> + timecounter_init(&mdev->clock, &mdev->cycles, ns);
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
> +
> + return 0;
> +}
> +
> +/**
> + * mlx4_en_phc_enable - enable or disable an ancillary feature
> + * @ptp: ptp clock structure
> + * @request: Desired resource to enable or disable
> + * @on: Caller passes one to enable or zero to disable
> + *
> + * Enable (or disable) ancillary features of the PHC subsystem.
> + * Currently, no ancillary features are supported.
> + **/
> +static int mlx4_en_phc_enable(struct ptp_clock_info __always_unused *ptp,
> + struct ptp_clock_request __always_unused *request,
> + int __always_unused on)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static const struct ptp_clock_info mlx4_en_ptp_clock_info = {
> + .owner = THIS_MODULE,
> + .max_adj = 100000000,
> + .n_alarm = 0,
> + .n_ext_ts = 0,
> + .n_per_out = 0,
> + .pps = 0,
> + .adjfreq = mlx4_en_phc_adjfreq,
> + .adjtime = mlx4_en_phc_adjtime,
> + .gettime = mlx4_en_phc_gettime,
> + .settime = mlx4_en_phc_settime,
> + .enable = mlx4_en_phc_enable,
> +};
> +
> void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
> {
> struct mlx4_dev *dev = mdev->dev;
> + unsigned long flags;
> u64 ns;
>
> memset(&mdev->cycles, 0, sizeof(mdev->cycles));
> @@ -127,9 +297,12 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
> mdev->cycles.shift = 14;
> mdev->cycles.mult =
> clocksource_khz2mult(1000 * dev->caps.hca_core_clock, mdev->cycles.shift);
> + mdev->nominal_c_mult = mdev->cycles.mult;
>
> + spin_lock_irqsave(&mdev->clock_lock, flags);
> timecounter_init(&mdev->clock, &mdev->cycles,
> ktime_to_ns(ktime_get_real()));
> + spin_unlock_irqrestore(&mdev->clock_lock, flags);
>
> /* Calculate period in seconds to call the overflow watchdog - to make
> * sure counter is checked at least once every wrap around.
> @@ -137,15 +310,18 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
> ns = cyclecounter_cyc2ns(&mdev->cycles, mdev->cycles.mask);
> do_div(ns, NSEC_PER_SEC / 2 / HZ);
> mdev->overflow_period = ns;
> -}
>
> -void mlx4_en_ptp_overflow_check(struct mlx4_en_dev *mdev)
> -{
> - bool timeout = time_is_before_jiffies(mdev->last_overflow_check +
> - mdev->overflow_period);
> + /* Configure the PHC */
> + mdev->ptp_clock_info = mlx4_en_ptp_clock_info;
> + snprintf(mdev->ptp_clock_info.name, 16, "mlx4 ptp");
>
> - if (timeout) {
> - timecounter_read(&mdev->clock);
> - mdev->last_overflow_check = jiffies;
> + mdev->ptp_clock = ptp_clock_register(&mdev->ptp_clock_info,
> + &mdev->pdev->dev);
> + if (IS_ERR(mdev->ptp_clock)) {
> + mdev->ptp_clock = NULL;
> + mlx4_err(mdev, "ptp_clock_register failed\n");
> + } else {
> + mlx4_info(mdev, "registered PHC clock\n");
> }
> +
> }
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> index 0596f9f..3e8d336 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> @@ -1193,6 +1193,9 @@ static int mlx4_en_get_ts_info(struct net_device *dev,
> info->rx_filters =
> (1 << HWTSTAMP_FILTER_NONE) |
> (1 << HWTSTAMP_FILTER_ALL);
> +
> + if (mdev->ptp_clock)
> + info->phc_index = ptp_clock_index(mdev->ptp_clock);
> }
>
> return ret;
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_main.c b/drivers/net/ethernet/mellanox/mlx4/en_main.c
> index 0d087b0..6268057 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_main.c
> @@ -196,6 +196,9 @@ static void mlx4_en_remove(struct mlx4_dev *dev, void *endev_ptr)
> if (mdev->pndev[i])
> mlx4_en_destroy_netdev(mdev->pndev[i]);
>
> + if (mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS)
> + mlx4_en_remove_timestamp(mdev);
> +
> flush_workqueue(mdev->workqueue);
> destroy_workqueue(mdev->workqueue);
> (void) mlx4_mr_free(dev, &mdev->mr);
> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> index f3758de..2b4083f 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> @@ -45,6 +45,7 @@
> #include <linux/dcbnl.h>
> #endif
> #include <linux/cpu_rmap.h>
> +#include <linux/ptp_clock_kernel.h>
>
> #include <linux/mlx4/device.h>
> #include <linux/mlx4/qp.h>
> @@ -373,10 +374,14 @@ struct mlx4_en_dev {
> u32 priv_pdn;
> spinlock_t uar_lock;
> u8 mac_removed[MLX4_MAX_PORTS + 1];
> + spinlock_t clock_lock;
> + u32 nominal_c_mult;
> struct cyclecounter cycles;
> struct timecounter clock;
> unsigned long last_overflow_check;
> unsigned long overflow_period;
> + struct ptp_clock *ptp_clock;
> + struct ptp_clock_info ptp_clock_info;
> };
>
>
> @@ -786,6 +791,7 @@ void mlx4_en_fill_hwtstamps(struct mlx4_en_dev *mdev,
> struct skb_shared_hwtstamps *hwts,
> u64 timestamp);
> void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev);
> +void mlx4_en_remove_timestamp(struct mlx4_en_dev *mdev);
> int mlx4_en_timestamp_config(struct net_device *dev,
> int tx_type,
> int rx_filter);
>
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