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Date: Thu, 25 Sep 2014 16:41:40 +0200
From: Richard Cochran <richardcochran@...il.com>
To: Luwei Zhou <b45643@...escale.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, shawn.guo@...aro.org,
bhutchings@...arflare.com, R49496@...escale.com,
b38611@...escale.com, b20596@...escale.com,
stephen@...workplumber.org
Subject: Re: [PATCH v1 3/4] net: fec: ptp: Enalbe PPS ouput based on ptp clock
On Thu, Sep 25, 2014 at 04:10:20PM +0800, Luwei Zhou wrote:
> FEC ptp timer has 4 channel compare/trigger function. It can be used to enable pps output.
> The pulse would be ouput high exactly on N second. The pulse ouput high on compare event mode
> is used to produce pulse per second. The pulse width would be one cycle based on ptp timer clock
> source.Since 31-bit ptp hardware timer is used, the timer will wrap more than 2 seconds. We need to
> reload the compare compare event about every 1 second.
>
> Signed-off-by: Luwei Zhou <b45643@...escale.com>
> ---
> drivers/net/ethernet/freescale/fec.h | 7 +
> drivers/net/ethernet/freescale/fec_main.c | 2 +
> drivers/net/ethernet/freescale/fec_ptp.c | 223 +++++++++++++++++++++++++++++-
> 3 files changed, 231 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
> index 26fb1de..f8e23e6 100644
> --- a/drivers/net/ethernet/freescale/fec.h
> +++ b/drivers/net/ethernet/freescale/fec.h
> @@ -481,12 +481,19 @@ struct fec_enet_private {
> unsigned int tx_pkts_itr;
> unsigned int tx_time_itr;
> unsigned int itr_clk_rate;
> +
> + /* pps */
> + int pps_channel;
> + unsigned int reload_period;
> + int pps_enable;
> + unsigned int next_counter;
> };
>
> void fec_ptp_init(struct platform_device *pdev);
> void fec_ptp_start_cyclecounter(struct net_device *ndev);
> int fec_ptp_set(struct net_device *ndev, struct ifreq *ifr);
> int fec_ptp_get(struct net_device *ndev, struct ifreq *ifr);
> +uint fec_ptp_check_pps_event(struct fec_enet_private *fep);
>
> /****************************************************************************/
> #endif /* FEC_H */
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index 3a4ec0f..5a4ce36 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1558,6 +1558,8 @@ fec_enet_interrupt(int irq, void *dev_id)
> complete(&fep->mdio_done);
> }
>
> + fec_ptp_check_pps_event(fep);
> +
> return ret;
> }
>
> diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
> index e2bf786..c55239d 100644
> --- a/drivers/net/ethernet/freescale/fec_ptp.c
> +++ b/drivers/net/ethernet/freescale/fec_ptp.c
> @@ -61,6 +61,24 @@
> #define FEC_T_INC_CORR_MASK 0x00007f00
> #define FEC_T_INC_CORR_OFFSET 8
>
> +#define FEC_T_CTRL_PINPER 0x00000080
> +#define FEC_T_TF0_MASK 0x00000001
> +#define FEC_T_TF0_OFFSET 0
> +#define FEC_T_TF1_MASK 0x00000002
> +#define FEC_T_TF1_OFFSET 1
> +#define FEC_T_TF2_MASK 0x00000004
> +#define FEC_T_TF2_OFFSET 2
> +#define FEC_T_TF3_MASK 0x00000008
> +#define FEC_T_TF3_OFFSET 3
> +#define FEC_T_TDRE_MASK 0x00000001
> +#define FEC_T_TDRE_OFFSET 0
> +#define FEC_T_TMODE_MASK 0x0000003C
> +#define FEC_T_TMODE_OFFSET 2
> +#define FEC_T_TIE_MASK 0x00000040
> +#define FEC_T_TIE_OFFSET 6
> +#define FEC_T_TF_MASK 0x00000080
> +#define FEC_T_TF_OFFSET 7
> +
> #define FEC_ATIME_CTRL 0x400
> #define FEC_ATIME 0x404
> #define FEC_ATIME_EVT_OFFSET 0x408
> @@ -69,9 +87,162 @@
> #define FEC_ATIME_INC 0x414
> #define FEC_TS_TIMESTAMP 0x418
>
> +#define FEC_TGSR 0x604
> +#define FEC_TCSR(n) (0x608 + n * 0x08)
> +#define FEC_TCCR(n) (0x60C + n * 0x08)
> +#define MAX_TIMER_CHANNEL 3
> +#define FEC_TMODE_TOGGLE 0x05
> +#define FEC_HIGH_PULSE 0x0F
> +
> #define FEC_CC_MULT (1 << 31)
> #define FEC_COUNTER_PERIOD (1 << 31)
> #define FEC_T_PERIOD_ONE_SEC (1000000000UL)
> +#define PPS_OUPUT_RELOAD_PERIOD FEC_T_PERIOD_ONE_SEC
> +
> +/**
> + * fec_ptp_enable_pps
> + * @fep: the fec_enet_private structure handle
> + * @enable: enable the channel pps output
> + *
> + * This function enble the PPS ouput on the timer channel.
> + */
> +static int fec_ptp_enable_pps(struct fec_enet_private *fep, uint enable)
> +{
> + unsigned long flags;
> + u32 val, tempval;
> + int inc;
> + struct timespec ts;
> + u64 ns;
> + u32 remainder;
> + val = 0;
> +
> + if (fep->pps_channel == -1 || fep->pps_channel > MAX_TIMER_CHANNEL) {
> + dev_err(&fep->pdev->dev, "Invalid pps channel\n");
> + return -EINVAL;
> + }
> +
> + if (!(fep->hwts_tx_en || fep->hwts_rx_en)) {
> + dev_err(&fep->pdev->dev, "No ptp stack is running\n");
> + return -EINVAL;
> + }
> +
> + if (fep->pps_enable == enable)
> + return 0;
> +
> + fep->reload_period = PPS_OUPUT_RELOAD_PERIOD;
> + inc = FEC_T_PERIOD_ONE_SEC / clk_get_rate(fep->clk_ptp);
> +
> + spin_lock_irqsave(&fep->tmreg_lock, flags);
> +
> + if (enable) {
> + /*
> + * clear capture or output compare interrupt status if have.
> + */
> + writel(FEC_T_TF_MASK, fep->hwp + FEC_TCSR(fep->pps_channel));
> +
> + /*
> + * It is recommended to doulbe check the TMODE field in the
> + * TCSR register to be cleared before the first compare counter
> + * is written into TCCR register. Just add a double check.
> + */
> + val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
> + do {
> + val &= ~(FEC_T_TMODE_MASK);
> + writel(val, fep->hwp + FEC_TCSR(fep->pps_channel));
> + val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
> + } while (val & FEC_T_TMODE_MASK);
> +
> + /*
> + * Dummy read counter to update the counter
> + */
> + timecounter_read(&fep->tc);
> + /*
> + * linux ptp is running. We want to find the first compare event
^^^^^^^^^^^^^^^^^^^^
What does this mean?
> + * in the next second point. So we need to know what the ptp time
> + * is now and how many nanoseconds is ahead to get next second.
> + * The remaining nanosecond ahead before the next second would be
> + * FEC_T_PERIOD_ONE_SEC - ts.tv_nsec. Add the remaining nanoseconds
> + * to current timer would be next second.
> + */
> + tempval = readl(fep->hwp + FEC_ATIME_CTRL);
> + tempval |= FEC_T_CTRL_CAPTURE;
> + writel(tempval, fep->hwp + FEC_ATIME_CTRL);
> +
> + tempval = readl(fep->hwp + FEC_ATIME);
> + /*
> + * Converse the ptp local counter to 1588 timestamp
^^^^^^^^
Convert?
> + */
> + ns = timecounter_cyc2time(&fep->tc, tempval);
> + ts.tv_sec = div_u64_rem(ns, 1000000000ULL, &remainder);
> + ts.tv_nsec = remainder;
> +
> + /*
> + * The tempval is less than 3 seconds, and so val is less than
> + * 4 seconds. No overflow for 32bit calculation.
> + */
> + val = FEC_T_PERIOD_ONE_SEC - (u32)ts.tv_nsec + tempval;
> +
> + /* Need to consider the situation that the current time is
> + * very close to the second point, which means FEC_T_PERIOD_ONE_SEC
> + * - ts.tv_nsec is close to be zero(For example 20ns); Since the timer
> + * is still running when we calculate the first compare event, it is
> + * possible that the remaining nanoseonds run out before the compare
> + * counter is calculated and written into TCCR register. To avoid
> + * this possibility, we will set the compare event to be the next
> + * of next second. The current setting is 31-bit timer and wrap
> + * around over 2 seconds. So it is okay to set the next of next
> + * seond for the timer.
> + */
> + val += FEC_T_PERIOD_ONE_SEC;
> +
> + /*
> + * We add (2 *FEC_T_PERIOD_ONE_SEC - (u32)ts.tv_nsec) to current
> + * ptp counter, which maybe cause 32-bit wrap. Since the
> + * (FEC_T_PERIOD_ONE_SEC - (u32)ts.tv_nsec) is less than 2 second.
> + * We can ensure the wrap will not cause issue. If the offset
> + * is bigger than fep->cc.mask would be a error.
> + */
> + val &= fep->cc.mask;
> + writel(val, fep->hwp + FEC_TCCR(fep->pps_channel));
> +
> + /*
> + * Calculate the second the compare event timestamp.
> + */
> + fep->next_counter = (val + fep->reload_period) & fep->cc.mask;
> +
> + /*
> + * Enable compare event when overflow
> + */
> + val = readl(fep->hwp + FEC_ATIME_CTRL);
> + val |= FEC_T_CTRL_PINPER;
> + writel(val, fep->hwp + FEC_ATIME_CTRL);
> +
> + /*
> + * Compare channel setting.
> + */
> + val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
> + val |= (1 << FEC_T_TF_OFFSET | 1 << FEC_T_TIE_OFFSET);
> + val &= ~(1 << FEC_T_TDRE_OFFSET);
> + val &= ~(FEC_T_TMODE_MASK);
> + val |= (FEC_HIGH_PULSE << FEC_T_TMODE_OFFSET);
> + writel(val, fep->hwp + FEC_TCSR(fep->pps_channel));
> +
> + /*
> + * Write the second compare event timestamp and calculate
> + * the third timestamp. Refer the TCCR register detail in the spec.
> + */
> + writel(fep->next_counter, fep->hwp + FEC_TCCR(fep->pps_channel));
> + fep->next_counter = (fep->next_counter + fep->reload_period) & fep->cc.mask;
> + } else {
> + writel(0, fep->hwp + FEC_TCSR(fep->pps_channel));
> + }
> +
> + fep->pps_enable = enable;
> + spin_unlock_irqrestore(&fep->tmreg_lock, flags);
> +
> + return 0;
> +}
> +
> /**
> * fec_ptp_read - read raw cycle counter (to be used by time counter)
> * @cc: the cyclecounter structure
> @@ -322,6 +493,15 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
> static int fec_ptp_enable(struct ptp_clock_info *ptp,
> struct ptp_clock_request *rq, int on)
> {
> + struct fec_enet_private *fep =
> + container_of(ptp, struct fec_enet_private, ptp_caps);
> + int ret = 0;
> +
> + if (rq->type == PTP_CLK_REQ_PPS) {
> + ret = fec_ptp_enable_pps(fep, on);
> +
> + return ret;
> + }
> return -EOPNOTSUPP;
> }
>
> @@ -427,6 +607,8 @@ void fec_ptp_init(struct platform_device *pdev)
> {
> struct net_device *ndev = platform_get_drvdata(pdev);
> struct fec_enet_private *fep = netdev_priv(ndev);
> + struct device_node *np = pdev->dev.of_node;
> + int err;
>
> fep->ptp_caps.owner = THIS_MODULE;
> snprintf(fep->ptp_caps.name, 16, "fec ptp");
> @@ -436,7 +618,7 @@ void fec_ptp_init(struct platform_device *pdev)
> fep->ptp_caps.n_ext_ts = 0;
> fep->ptp_caps.n_per_out = 0;
> fep->ptp_caps.n_pins = 0;
> - fep->ptp_caps.pps = 0;
> + fep->ptp_caps.pps = 1;
> fep->ptp_caps.adjfreq = fec_ptp_adjfreq;
> fep->ptp_caps.adjtime = fec_ptp_adjtime;
> fep->ptp_caps.gettime = fec_ptp_gettime;
> @@ -444,6 +626,10 @@ void fec_ptp_init(struct platform_device *pdev)
> fep->ptp_caps.enable = fec_ptp_enable;
>
> fep->cycle_speed = clk_get_rate(fep->clk_ptp);
> + err = of_property_read_u32(np, "pps-channel",
> + &fep->pps_channel);
Please do not make another DT property for this.
Instead, use the PTP_PIN_SET/GETFUNC interface. You can add a new
enumeration value to ptp_pin_function, like PTP_PF_PPS.
Thanks,
Richard
> + if (err)
> + fep->pps_channel = -1;
>
> spin_lock_init(&fep->tmreg_lock);
>
> @@ -459,3 +645,38 @@ void fec_ptp_init(struct platform_device *pdev)
>
> schedule_delayed_work(&fep->time_keep, HZ);
> }
> +
> +/**
> + * fec_ptp_check_pps_event
> + * @fep: the fec_enet_private structure handle
> + *
> + * This function check the pps event and reload the timer compare counter.
> + */
> +uint fec_ptp_check_pps_event(struct fec_enet_private *fep)
> +{
> + u32 val;
> + u8 channel = fep->pps_channel;
> + struct ptp_clock_event event;
> +
> + val = readl(fep->hwp + FEC_TCSR(channel));
> + if (val & FEC_T_TF_MASK) {
> + /*
> + * Write the next next compare(not the next according the spec) value to the register
> + */
> + writel(fep->next_counter, fep->hwp + FEC_TCCR(channel));
> + do {
> + writel(val, fep->hwp + FEC_TCSR(channel));
> + } while (readl(fep->hwp + FEC_TCSR(channel)) & FEC_T_TF_MASK);
> +
> + /*
> + * Update the counter;
> + */
> + fep->next_counter = (fep->next_counter + fep->reload_period) & fep->cc.mask;
> +
> + event.type = PTP_CLOCK_PPS;
> + ptp_clock_event(fep->ptp_clock, &event);
> + return 1;
> + }
> +
> + return 0;
> +}
> --
> 1.9.1
>
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