[PATCH v2 4/4] net: fec: ptp: Enalbe PPS ouput based on ptp clock

[Luwei Zhou <b45643@freescale.com>]

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@freescale.com>
---
 drivers/net/ethernet/freescale/fec.h      |   7 +
 drivers/net/ethernet/freescale/fec_main.c |   2 +
 drivers/net/ethernet/freescale/fec_ptp.c  | 217 +++++++++++++++++++++++++++++-
 3 files changed, 224 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index b2e263e..1dbc014 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -485,12 +485,19 @@ struct fec_enet_private {
 
 	/* ptp clock period in ns*/
 	unsigned int ptp_inc;
+
+	/* 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 2c73434..5342f45 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1571,6 +1571,8 @@ 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 036d956..4ac2ff7 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 +87,160 @@
 #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_NSEC_PER_SEC	(1000000000UL)
+#define PPS_OUPUT_RELOAD_PERIOD	FEC_T_NSEC_PER_SEC
+
+/**
+ * The default PPS ouput pin configuration.
+ * User can set/get the PPS output channel
+ * via PTP_PIN_SET/GETFUNC ptp interface.
+ */
+static struct ptp_pin_desc fec_pps_pin = {
+	.name = "fec_pps_pin_config",
+	.index = 0,
+	.func = PTP_PF_PPS,
+	.chan = 0,
+};
+
+/**
+ * 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;
+	struct ptp_pin_desc *pin_config = fep->ptp_caps.pin_config;
+	val = 0;
+
+	if (pin_config->func != PTP_PF_PPS) {
+		dev_err(&fep->pdev->dev, "No pps pin function\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->pps_channel = pin_config->chan;
+	fep->reload_period = PPS_OUPUT_RELOAD_PERIOD;
+	inc = fep->ptp_inc;
+
+	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);
+		/* We want to find the first compare event 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_NSEC_PER_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);
+		/* Convert the ptp local counter to 1588 timestamp */
+		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_NSEC_PER_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_NSEC_PER_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_NSEC_PER_SEC;
+
+		/* We add (2 *FEC_T_NSEC_PER_SEC - (u32)ts.tv_nsec) to current
+		 * ptp counter, which maybe cause 32-bit wrap. Since the
+		 * (FEC_T_NSEC_PER_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
@@ -315,6 +484,15 @@ 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;
 }
 
@@ -428,8 +606,10 @@ void fec_ptp_init(struct platform_device *pdev)
 	fep->ptp_caps.n_alarm = 0;
 	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.n_pps_chan = MAX_TIMER_CHANNEL;
+	fep->ptp_caps.n_pins = 1;
+	fep->ptp_caps.pin_config = &fec_pps_pin;
+	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;
@@ -453,3 +633,36 @@ 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