can: rockchip_canfd: add hardware timestamping support

Add support for hardware based timestamping.

Tested-by: Alibek Omarov <[e-mail]>
Acked-by: Heiko Stuebner <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/rockchip/rockchip_canfd-core.c

···
 
 	rkcanfd_chip_fifo_setup(priv);
 	rkcanfd_timestamp_init(priv);
+	rkcanfd_timestamp_start(priv);
+
 	rkcanfd_set_bittiming(priv);
 
 	rkcanfd_chip_interrupts_disable(priv);
···
 {
 	priv->can.state = state;
 
+	rkcanfd_timestamp_stop(priv);
 	__rkcanfd_chip_stop(priv, state);
 }
 
···
 {
 	priv->can.state = state;
 
+	rkcanfd_timestamp_stop_sync(priv);
 	__rkcanfd_chip_stop(priv, state);
 }
 
···
 	*timestamp = rkcanfd_get_timestamp(priv);
 
 	skb = alloc_can_err_skb(priv->ndev, cf);
+	if (skb)
+		rkcanfd_skb_set_timestamp(priv, skb, *timestamp);
 
 	return skb;
 }

drivers/net/can/rockchip/rockchip_canfd-ethtool.c

···
 }
 
 static const struct ethtool_ops rkcanfd_ethtool_ops = {
-	.get_ts_info = ethtool_op_get_ts_info,
+	.get_ts_info = can_ethtool_op_get_ts_info_hwts,
 	.get_strings = rkcanfd_ethtool_get_strings,
 	.get_sset_count = rkcanfd_ethtool_get_sset_count,
 	.get_ethtool_stats = rkcanfd_ethtool_get_ethtool_stats,

drivers/net/can/rockchip/rockchip_canfd-rx.c

···
 	}
 
 	memcpy(skb_cfd, cfd, len);
+	rkcanfd_skb_set_timestamp(priv, skb, header->ts);
 
 	err = can_rx_offload_queue_timestamp(&priv->offload, skb, header->ts);
 	if (err)

drivers/net/can/rockchip/rockchip_canfd-timestamp.c

···
 //               Marc Kleine-Budde <[e-mail]>
 //
 
+#include <linux/clocksource.h>
+
 #include "rockchip_canfd.h"
+
+static u64 rkcanfd_timestamp_read(const struct cyclecounter *cc)
+{
+	const struct rkcanfd_priv *priv = container_of(cc, struct rkcanfd_priv, cc);
+
+	return rkcanfd_get_timestamp(priv);
+}
+
+void rkcanfd_skb_set_timestamp(const struct rkcanfd_priv *priv,
+			       struct sk_buff *skb, const u32 timestamp)
+{
+	struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
+	u64 ns;
+
+	ns = timecounter_cyc2time(&priv->tc, timestamp);
+
+	hwtstamps->hwtstamp = ns_to_ktime(ns);
+}
+
+static void rkcanfd_timestamp_work(struct work_struct *work)
+{
+	const struct delayed_work *delayed_work = to_delayed_work(work);
+	struct rkcanfd_priv *priv;
+
+	priv = container_of(delayed_work, struct rkcanfd_priv, timestamp);
+	timecounter_read(&priv->tc);
+
+	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
+}
 
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv)
 {
-	u32 reg;
+	const struct can_bittiming *dbt = &priv->can.data_bittiming;
+	const struct can_bittiming *bt = &priv->can.bittiming;
+	struct cyclecounter *cc = &priv->cc;
+	u32 bitrate, div, reg, rate;
+	u64 work_delay_ns;
+	u64 max_cycles;
 
-	reg = RKCANFD_REG_TIMESTAMP_CTRL_TIME_BASE_COUNTER_ENABLE;
+	/* At the standard clock rate of 300Mhz on the rk3658, the 32
+	 * bit timer overflows every 14s. This means that we have to
+	 * poll it quite often to avoid missing a wrap around.
+	 *
+	 * Divide it down to a reasonable rate, at least twice the bit
+	 * rate.
+	 */
+	bitrate = max(bt->bitrate, dbt->bitrate);
+	div = min(DIV_ROUND_UP(priv->can.clock.freq, bitrate * 2),
+		  FIELD_MAX(RKCANFD_REG_TIMESTAMP_CTRL_TIME_BASE_COUNTER_PRESCALE) + 1);
+
+	reg = FIELD_PREP(RKCANFD_REG_TIMESTAMP_CTRL_TIME_BASE_COUNTER_PRESCALE,
+			 div - 1) |
+		RKCANFD_REG_TIMESTAMP_CTRL_TIME_BASE_COUNTER_ENABLE;
 	rkcanfd_write(priv, RKCANFD_REG_TIMESTAMP_CTRL, reg);
+
+	cc->read = rkcanfd_timestamp_read;
+	cc->mask = CYCLECOUNTER_MASK(32);
+
+	rate = priv->can.clock.freq / div;
+	clocks_calc_mult_shift(&cc->mult, &cc->shift, rate, NSEC_PER_SEC,
+			       RKCANFD_TIMESTAMP_WORK_MAX_DELAY_SEC);
+
+	max_cycles = div_u64(ULLONG_MAX, cc->mult);
+	max_cycles = min(max_cycles, cc->mask);
+	work_delay_ns = clocksource_cyc2ns(max_cycles, cc->mult, cc->shift) / 3;
+	priv->work_delay_jiffies = nsecs_to_jiffies(work_delay_ns);
+	INIT_DELAYED_WORK(&priv->timestamp, rkcanfd_timestamp_work);
+
+	netdev_dbg(priv->ndev, "clock=%lu.%02luMHz bitrate=%lu.%02luMBit/s div=%u rate=%lu.%02luMHz mult=%u shift=%u delay=%lus\n",
+		   priv->can.clock.freq / MEGA,
+		   priv->can.clock.freq % MEGA / KILO / 10,
+		   bitrate / MEGA,
+		   bitrate % MEGA / KILO / 100,
+		   div,
+		   rate / MEGA,
+		   rate % MEGA / KILO / 10,
+		   cc->mult, cc->shift,
+		   priv->work_delay_jiffies / HZ);
+}
+
+void rkcanfd_timestamp_start(struct rkcanfd_priv *priv)
+{
+	timecounter_init(&priv->tc, &priv->cc, ktime_get_real_ns());
+
+	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
+}
+
+void rkcanfd_timestamp_stop(struct rkcanfd_priv *priv)
+{
+	cancel_delayed_work(&priv->timestamp);
+}
+
+void rkcanfd_timestamp_stop_sync(struct rkcanfd_priv *priv)
+{
+	cancel_delayed_work_sync(&priv->timestamp);
 }

drivers/net/can/rockchip/rockchip_canfd-tx.c

···
 {
 	struct net_device_stats *stats = &priv->ndev->stats;
 	unsigned int tx_tail;
+	struct sk_buff *skb;
 
 	tx_tail = rkcanfd_get_tx_tail(priv);
+	skb = priv->can.echo_skb[tx_tail];
 
 	/* Manual handling of CAN Bus Error counters. See
 	 * rkcanfd_get_corrected_berr_counter() for detailed
···
 	if (priv->bec.txerr)
 		priv->bec.txerr--;
 
+	if (skb)
+		rkcanfd_skb_set_timestamp(priv, skb, ts);
 	stats->tx_bytes +=
 		can_rx_offload_get_echo_skb_queue_timestamp(&priv->offload,
 							    tx_tail, ts,

drivers/net/can/rockchip/rockchip_canfd.h

···
 #include <linux/netdevice.h>
 #include <linux/reset.h>
 #include <linux/skbuff.h>
+#include <linux/timecounter.h>
 #include <linux/types.h>
 #include <linux/u64_stats_sync.h>
 #include <linux/units.h>
···
 	u32 reg_int_mask_default;
 	struct rkcanfd_devtype_data devtype_data;
 
+	struct cyclecounter cc;
+	struct timecounter tc;
+	struct delayed_work timestamp;
+	unsigned long work_delay_jiffies;
+
 	struct can_berr_counter bec;
 
 	struct rkcanfd_stats stats;
···
 
 int rkcanfd_handle_rx_int(struct rkcanfd_priv *priv);
 
+void rkcanfd_skb_set_timestamp(const struct rkcanfd_priv *priv,
+			       struct sk_buff *skb, const u32 timestamp);
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv);
+void rkcanfd_timestamp_start(struct rkcanfd_priv *priv);
+void rkcanfd_timestamp_stop(struct rkcanfd_priv *priv);
+void rkcanfd_timestamp_stop_sync(struct rkcanfd_priv *priv);
 
 unsigned int rkcanfd_get_effective_tx_free(const struct rkcanfd_priv *priv);
 void rkcanfd_xmit_retry(struct rkcanfd_priv *priv);