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Date: Thu, 25 Sep 2014 16:10:19 +0800
From: Luwei Zhou <b45643@...escale.com>
To: <davem@...emloft.net>, <richardcochran@...il.com>
CC: <netdev@...r.kernel.org>, <shawn.guo@...aro.org>,
<bhutchings@...arflare.com>, <R49496@...escale.com>,
<b38611@...escale.com>, <b20596@...escale.com>,
<stephen@...workplumber.org>
Subject: [PATCH v1 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_ptp.c | 68 +++++++++++++++++++++++++++-----
1 file changed, 58 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index 8016bdd..e2bf786 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_PERIOD_ONE_SEC (1000000000UL)
/**
* fec_ptp_read - read raw cycle counter (to be used by time counter)
* @cc: the cyclecounter structure
@@ -145,33 +146,65 @@ 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 ptp_ts_clk, ptp_inc;
+ u32 corr_inc, corr_period;
+ u32 corr_ns;
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);
+ ptp_ts_clk = clk_get_rate(fep->clk_ptp);
+ ptp_inc = FEC_T_PERIOD_ONE_SEC / ptp_ts_clk;
+
+ /*
+ * In theory, corr_inc/corr_period = ppb/FEC_T_PERIOD_ONE_SEC;
+ * Try to find the corr_inc between 1 to ptp_inc to meet adjustment
+ * requirement.
+ */
+ for (i = 1; i <= ptp_inc; i++) {
+ if (((i * FEC_T_PERIOD_ONE_SEC) / ppb) >= ptp_inc) {
+ corr_inc = i;
+ corr_period = ((i * FEC_T_PERIOD_ONE_SEC) /
+ (ptp_inc * ppb));
+ break;
+ }
+ }
+ /*
+ * Not found? Set it to high value - double speed
+ * correct in every clock step.
+ */
+ if (i > ptp_inc) {
+ corr_inc = ptp_inc;
+ corr_period = 1;
+ }
+
+ if (neg_adj)
+ corr_ns = ptp_inc - corr_inc;
+ else
+ corr_ns = ptp_inc + corr_inc;
spin_lock_irqsave(&fep->tmreg_lock, flags);
+
+ 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 set cycle_last in tc to now.
- * So use adjusted mult to calculate when next call
- * timercounter_read.
+ * dummy read to update the timer.
*/
timecounter_read(&fep->tc);
- fep->cc.mult = neg_adj ? mult - diff : mult + diff;
-
spin_unlock_irqrestore(&fep->tmreg_lock, flags);
return 0;
@@ -190,12 +223,20 @@ 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 +287,7 @@ 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 +298,14 @@ 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);
--
1.9.1
--
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