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Date: Mon, 29 Sep 2014 02:13:52 +0000
From: "fugang.duan@...escale.com" <fugang.duan@...escale.com>
To: "luwei.zhou@...escale.com" <luwei.zhou@...escale.com>,
"davem@...emloft.net" <davem@...emloft.net>,
"richardcochran@...il.com" <richardcochran@...il.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
"bhutchings@...arflare.com" <bhutchings@...arflare.com>,
"Fabio.Estevam@...escale.com" <Fabio.Estevam@...escale.com>,
"Frank.Li@...escale.com" <Frank.Li@...escale.com>,
"stephen@...workplumber.org" <stephen@...workplumber.org>
Subject: RE: [PATCH v2 2/4] net: fec: ptp: Use hardware algorithm to adjust
PTP counter.
From: Luwei Zhou <b45643@...escale.com> Sent: Sunday, September 28, 2014 12:20 PM + 0800
>To: davem@...emloft.net; richardcochran@...il.com
>Cc: netdev@...r.kernel.org; shawn.guo@...aro.org;
>bhutchings@...arflare.com; Estevam Fabio-R49496; Duan Fugang-B38611; Li
>Frank-B20596; stephen@...workplumber.org
>Subject: [PATCH v2 2/4] net: fec: ptp: Use hardware algorithm to adjust
>PTP counter.
>
>The FEC IP supports hardware adjustment for ptp timer. Refer to the
>description of ENET_ATCOR and ENET_ATINC registers in the spec about the
>hardware adjustment. This patch uses hardware support to adjust the ptp
>offset and frequency on the slave side.
>
>Signed-off-by: Luwei Zhou <b45643@...escale.com>
>Signed-off-by: Frank Li <Frank.Li@...escale.com>
>Signed-off-by: Fugang Duan <b38611@...escale.com>
>---
> drivers/net/ethernet/freescale/fec.h | 3 ++
> drivers/net/ethernet/freescale/fec_ptp.c | 66 ++++++++++++++++++++++++++-
>-----
> 2 files changed, 57 insertions(+), 12 deletions(-)
>
>diff --git a/drivers/net/ethernet/freescale/fec.h
>b/drivers/net/ethernet/freescale/fec.h
>index 354a309..b2e263e 100644
>--- a/drivers/net/ethernet/freescale/fec.h
>+++ b/drivers/net/ethernet/freescale/fec.h
>@@ -482,6 +482,9 @@ struct fec_enet_private {
> unsigned int tx_pkts_itr;
> unsigned int tx_time_itr;
> unsigned int itr_clk_rate;
>+
>+ /* ptp clock period in ns*/
>+ unsigned int ptp_inc;
> };
>
> void fec_ptp_init(struct platform_device *pdev); diff --git
>a/drivers/net/ethernet/freescale/fec_ptp.c
>b/drivers/net/ethernet/freescale/fec_ptp.c
>index 8016bdd..036d956 100644
>--- a/drivers/net/ethernet/freescale/fec_ptp.c
>+++ b/drivers/net/ethernet/freescale/fec_ptp.c
>@@ -71,6 +71,7 @@
>
> #define FEC_CC_MULT (1 << 31)
> #define FEC_COUNTER_PERIOD (1 << 31)
>+#define FEC_T_NSEC_PER_SEC (1000000000UL)
Don't need redefine it, use NSEC_PER_SEC instead.
> /**
> * fec_ptp_read - read raw cycle counter (to be used by time counter)
> * @cc: the cyclecounter structure
>@@ -145,32 +146,59 @@ void fec_ptp_start_cyclecounter(struct net_device
>*ndev)
> */
> static int fec_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb) {
>- u64 diff;
> unsigned long flags;
> int neg_adj = 0;
>- u32 mult = FEC_CC_MULT;
>+ u32 i, tmp;
>+ u32 corr_inc, corr_period;
>+ u32 corr_ns;
>+ u64 lhs, rhs;
>
> struct fec_enet_private *fep =
> container_of(ptp, struct fec_enet_private, ptp_caps);
>
>+ if (ppb == 0)
>+ return 0;
>+
> if (ppb < 0) {
> ppb = -ppb;
> neg_adj = 1;
> }
>
>- diff = mult;
>- diff *= ppb;
>- diff = div_u64(diff, 1000000000ULL);
>+ /* In theory, corr_inc/corr_period = ppb/FEC_T_NSEC_PER_SEC;
>+ * Try to find the corr_inc between 1 to fep->ptp_inc to
>+ * meet adjustment requirement.
>+ */
>+ lhs = FEC_T_NSEC_PER_SEC;
>+ rhs = (u64)ppb * (u64)fep->ptp_inc;
>+ for (i = 1; i <= fep->ptp_inc; i++) {
>+ if (lhs >= rhs) {
>+ corr_inc = i;
>+ corr_period = div_u64(lhs, rhs);
>+ break;
>+ }
>+ lhs += FEC_T_NSEC_PER_SEC;
>+ }
>+ /* Not found? Set it to high value - double speed
>+ * correct in every clock step.
>+ */
>+ if (i > fep->ptp_inc) {
>+ corr_inc = fep->ptp_inc;
>+ corr_period = 1;
>+ }
>+
>+ if (neg_adj)
>+ corr_ns = fep->ptp_inc - corr_inc;
>+ else
>+ corr_ns = fep->ptp_inc + corr_inc;
>
> spin_lock_irqsave(&fep->tmreg_lock, flags);
>- /*
>- * dummy read to set cycle_last in tc to now.
>- * So use adjusted mult to calculate when next call
>- * timercounter_read.
>- */
>- timecounter_read(&fep->tc);
>
>- fep->cc.mult = neg_adj ? mult - diff : mult + diff;
>+ tmp = readl(fep->hwp + FEC_ATIME_INC) & FEC_T_INC_MASK;
>+ tmp |= corr_ns << FEC_T_INC_CORR_OFFSET;
>+ writel(tmp, fep->hwp + FEC_ATIME_INC);
>+ writel(corr_period, fep->hwp + FEC_ATIME_CORR);
>+ /* dummy read to update the timer. */
>+ timecounter_read(&fep->tc);
>
> spin_unlock_irqrestore(&fep->tmreg_lock, flags);
>
>@@ -190,12 +218,19 @@ static int fec_ptp_adjtime(struct ptp_clock_info
>*ptp, s64 delta)
> container_of(ptp, struct fec_enet_private, ptp_caps);
> unsigned long flags;
> u64 now;
>+ u32 counter;
>
> spin_lock_irqsave(&fep->tmreg_lock, flags);
>
> now = timecounter_read(&fep->tc);
> now += delta;
>
>+ /* Get the timer value based on adjusted timestamp.
>+ * Update the counter with the masked value.
>+ */
>+ counter = now & fep->cc.mask;
>+ writel(counter, fep->hwp + FEC_ATIME);
>+
> /* reset the timecounter */
> timecounter_init(&fep->tc, &fep->cc, now);
>
>@@ -246,6 +281,7 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
>
> u64 ns;
> unsigned long flags;
>+ u32 counter;
>
> mutex_lock(&fep->ptp_clk_mutex);
> /* Check the ptp clock */
>@@ -256,8 +292,13 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
>
> ns = ts->tv_sec * 1000000000ULL;
> ns += ts->tv_nsec;
>+ /* Get the timer value based on timestamp.
>+ * Update the counter with the masked value.
>+ */
>+ counter = ns & fep->cc.mask;
>
> spin_lock_irqsave(&fep->tmreg_lock, flags);
>+ writel(counter, fep->hwp + FEC_ATIME);
> timecounter_init(&fep->tc, &fep->cc, ns);
> spin_unlock_irqrestore(&fep->tmreg_lock, flags);
> mutex_unlock(&fep->ptp_clk_mutex);
>@@ -396,6 +437,7 @@ void fec_ptp_init(struct platform_device *pdev)
> fep->ptp_caps.enable = fec_ptp_enable;
>
> fep->cycle_speed = clk_get_rate(fep->clk_ptp);
>+ fep->ptp_inc = FEC_T_NSEC_PER_SEC / fep->cycle_speed;
>
> spin_lock_init(&fep->tmreg_lock);
>
>--
>1.9.1
Regards,
Andy
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