[RFC Patch net-next v2 4/8] net: dsa: microchip: Manipulating absolute time using ptp hw clock

[Arun Ramadoss <arun.ramadoss@microchip.com>]

This patch is used for reconstructing the absolute time from the 32bit
hardware time stamping value. The do_aux ioctl is used for reading the
ptp hardware clock and store it to global variable.
The timestamped value in tail tag during rx and register during tx are
32 bit value (2 bit seconds and 30 bit nanoseconds). The time taken to
read entire ptp clock will be time consuming. In order to speed up, the
software clock is maintained. This clock time will be added to 32 bit
timestamp to get the absolute time stamp.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
---
 drivers/net/dsa/microchip/ksz_common.h |  1 +
 drivers/net/dsa/microchip/ksz_ptp.c    | 59 +++++++++++++++++++++++++-
 drivers/net/dsa/microchip/ksz_ptp.h    |  3 ++
 3 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 605d0a295288..4c092376fc89 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -7,6 +7,7 @@
 #ifndef __KSZ_COMMON_H
 #define __KSZ_COMMON_H
 
+#include <linux/dsa/ksz_common.h>
 #include <linux/etherdevice.h>
 #include <linux/kernel.h>
 #include <linux/mutex.h>
diff --git a/drivers/net/dsa/microchip/ksz_ptp.c b/drivers/net/dsa/microchip/ksz_ptp.c
index 1b2880d013ed..5db67dc6a565 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.c
+++ b/drivers/net/dsa/microchip/ksz_ptp.c
@@ -24,12 +24,22 @@
 
 static int ksz_ptp_enable_mode(struct ksz_device *dev, bool enable)
 {
+	struct ksz_ptp_data *ptp_data = &dev->ptp_data;
 	u16 data = 0;
+	int ret;
 
 	/* Enable PTP mode */
-	if (enable)
+	if (enable) {
 		data = PTP_ENABLE;
 
+		/* Schedule cyclic call of ksz_ptp_do_aux_work() */
+		ret = ptp_schedule_worker(ptp_data->clock, 0);
+		if (ret)
+			return ret;
+	} else {
+		ptp_cancel_worker_sync(ptp_data->clock);
+	}
+
 	return ksz_rmw16(dev, REG_PTP_MSG_CONF1, PTP_ENABLE, data);
 }
 
@@ -226,6 +236,12 @@ static int ksz_ptp_settime(struct ptp_clock_info *ptp,
 
 	/* Load PTP clock from shadow registers */
 	ret = ksz_rmw16(dev, REG_PTP_CLK_CTRL, PTP_LOAD_TIME, PTP_LOAD_TIME);
+	if (ret)
+		goto error_return;
+
+	spin_lock_bh(&ptp_data->clock_lock);
+	ptp_data->clock_time = *ts;
+	spin_unlock_bh(&ptp_data->clock_lock);
 
 error_return:
 	mutex_unlock(&ptp_data->lock);
@@ -280,6 +296,7 @@ static int ksz_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
 {
 	struct ksz_ptp_data *ptp_data = ptp_caps_to_data(ptp);
 	struct ksz_device *dev = ptp_data_to_ksz_dev(ptp_data);
+	struct timespec64 delta64 = ns_to_timespec64(delta);
 	s32 sec, nsec;
 	u16 data16;
 	int ret;
@@ -312,15 +329,51 @@ static int ksz_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
 		data16 |= PTP_STEP_DIR;
 
 	ret = ksz_write16(dev, REG_PTP_CLK_CTRL, data16);
+	if (ret)
+		goto error_return;
+
+	spin_lock_bh(&ptp_data->clock_lock);
+	ptp_data->clock_time = timespec64_add(ptp_data->clock_time, delta64);
+	spin_unlock_bh(&ptp_data->clock_lock);
 
 error_return:
 	mutex_unlock(&ptp_data->lock);
 	return ret;
 }
 
+/*  Function is pointer to the do_aux_work in the ptp_clock capability */
+static long ksz_ptp_do_aux_work(struct ptp_clock_info *ptp)
+{
+	struct ksz_ptp_data *ptp_data = ptp_caps_to_data(ptp);
+	struct ksz_device *dev = ptp_data_to_ksz_dev(ptp_data);
+	struct timespec64 ts;
+
+	mutex_lock(&ptp_data->lock);
+	_ksz_ptp_gettime(dev, &ts);
+	mutex_unlock(&ptp_data->lock);
+
+	spin_lock_bh(&ptp_data->clock_lock);
+	ptp_data->clock_time = ts;
+	spin_unlock_bh(&ptp_data->clock_lock);
+
+	return HZ;  /* reschedule in 1 second */
+}
+
 static int ksz_ptp_start_clock(struct ksz_device *dev)
 {
-	return ksz_rmw16(dev, REG_PTP_CLK_CTRL, PTP_CLK_ENABLE, PTP_CLK_ENABLE);
+	struct ksz_ptp_data *ptp_data = &dev->ptp_data;
+	int ret;
+
+	ret = ksz_rmw16(dev, REG_PTP_CLK_CTRL, PTP_CLK_ENABLE, PTP_CLK_ENABLE);
+	if (ret)
+		return ret;
+
+	spin_lock_bh(&ptp_data->clock_lock);
+	ptp_data->clock_time.tv_sec = 0;
+	ptp_data->clock_time.tv_nsec = 0;
+	spin_unlock_bh(&ptp_data->clock_lock);
+
+	return 0;
 }
 
 static const struct ptp_clock_info ksz_ptp_caps = {
@@ -331,6 +384,7 @@ static const struct ptp_clock_info ksz_ptp_caps = {
 	.settime64	= ksz_ptp_settime,
 	.adjfine	= ksz_ptp_adjfine,
 	.adjtime	= ksz_ptp_adjtime,
+	.do_aux_work	= ksz_ptp_do_aux_work,
 };
 
 int ksz_ptp_clock_register(struct dsa_switch *ds)
@@ -340,6 +394,7 @@ int ksz_ptp_clock_register(struct dsa_switch *ds)
 	int ret;
 
 	mutex_init(&ptp_data->lock);
+	spin_lock_init(&ptp_data->clock_lock);
 
 	ptp_data->caps = ksz_ptp_caps;
 
diff --git a/drivers/net/dsa/microchip/ksz_ptp.h b/drivers/net/dsa/microchip/ksz_ptp.h
index 4c024cc9d935..09c0e58c365e 100644
--- a/drivers/net/dsa/microchip/ksz_ptp.h
+++ b/drivers/net/dsa/microchip/ksz_ptp.h
@@ -13,6 +13,9 @@ struct ksz_ptp_data {
 	struct ptp_clock *clock;
 	/* Serializes all operations on the PTP hardware clock */
 	struct mutex lock;
+	/* lock for accessing the clock_time */
+	spinlock_t clock_lock;
+	struct timespec64 clock_time;
 };
 
 int ksz_ptp_clock_register(struct dsa_switch *ds);
-- 
2.36.1