Date:   Thu, 15 Sep 2022 12:50:27 +0200
From:   Pavel Pisa <pisa@....felk.cvut.cz>
To:     Matej Vasilevski <matej.vasilevski@...nam.cz>
Cc:     Ondrej Ille <ondrej.ille@...il.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "Marc Kleine-Budde" <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v4 2/3] can: ctucanfd: add HW timestamps to RX and error CAN frames

Dear Matej Vasilevski,

thanks much for the work on HW timestamping. For others, there
is a little wider view and summary of our long term work available
in CAN in a recent Automation Newletter magazine article.

  https://can-newsletter.org/uploads/media/raw/a9abe317ae034be55d99fee4410ad70e.pdf

I am happy that you have studied and added clock and power management
support based on discussion with Marc Kleine-Budde.
I see you have added these for "ts-clk". I am not sure if
there are not missing some more calls for "core-clk".
It is questionable if these clocks needs to be prepared
by device, because these clock drive AXI/APB/... bus interface
on which is CTU CAN FD core mapped so clocks has to be enabled
by bus driver anyway to make given address range accessible.

It is not strictly HW timestamping related either. So if the patch
is accepted in the current form I can prepare follow up patch
if the result of discussion is that additional calls are required.

The position to discuss are highlighted inline


On Thursday 15 of September 2022 01:39:43 Matej Vasilevski wrote:
> This patch adds support for retrieving hardware timestamps to RX and
> error CAN frames. It uses timecounter and cyclecounter structures,
> because the timestamping counter width depends on the IP core integration
> (it might not always be 64-bit).
> For platform devices, you should specify "ts-clk" clock in device tree.
> For PCI devices, the timestamping frequency is assumed to be the same
> as bus frequency.
>
> Signed-off-by: Matej Vasilevski <matej.vasilevski@...nam.cz>
> ---
>  drivers/net/can/ctucanfd/Makefile             |   2 +-
>  drivers/net/can/ctucanfd/ctucanfd.h           |  20 ++
>  drivers/net/can/ctucanfd/ctucanfd_base.c      | 239 ++++++++++++++++--
>  drivers/net/can/ctucanfd/ctucanfd_pci.c       |   5 +-
>  drivers/net/can/ctucanfd/ctucanfd_platform.c  |   5 +-
>  drivers/net/can/ctucanfd/ctucanfd_timestamp.c |  70 +++++
>  6 files changed, 318 insertions(+), 23 deletions(-)
>  create mode 100644 drivers/net/can/ctucanfd/ctucanfd_timestamp.c
>
> diff --git a/drivers/net/can/ctucanfd/Makefile
> b/drivers/net/can/ctucanfd/Makefile index 8078f1f2c30f..a36e66f2cea7 100644
> --- a/drivers/net/can/ctucanfd/Makefile
> +++ b/drivers/net/can/ctucanfd/Makefile
> @@ -4,7 +4,7 @@
>  #
>
>  obj-$(CONFIG_CAN_CTUCANFD) := ctucanfd.o
> -ctucanfd-y := ctucanfd_base.o
> +ctucanfd-y := ctucanfd_base.o ctucanfd_timestamp.o
>
>  obj-$(CONFIG_CAN_CTUCANFD_PCI) += ctucanfd_pci.o
>  obj-$(CONFIG_CAN_CTUCANFD_PLATFORM) += ctucanfd_platform.o
> diff --git a/drivers/net/can/ctucanfd/ctucanfd.h
> b/drivers/net/can/ctucanfd/ctucanfd.h index 0e9904f6a05d..b3ee583234b0
> 100644
> --- a/drivers/net/can/ctucanfd/ctucanfd.h
> +++ b/drivers/net/can/ctucanfd/ctucanfd.h
> @@ -23,6 +23,10 @@
>  #include <linux/netdevice.h>
>  #include <linux/can/dev.h>
>  #include <linux/list.h>
> +#include <linux/timecounter.h>
> +#include <linux/workqueue.h>
> +
> +#define CTUCANFD_MAX_WORK_DELAY_SEC 3600U
>
>  enum ctu_can_fd_can_registers;
>
> @@ -51,6 +55,15 @@ struct ctucan_priv {
>  	u32 rxfrm_first_word;
>
>  	struct list_head peers_on_pdev;
> +
> +	struct cyclecounter cc;
> +	struct timecounter tc;
> +	spinlock_t tc_lock; /* spinlock to guard access tc->cycle_last */
> +	struct delayed_work timestamp;
> +	struct clk *timestamp_clk;
> +	unsigned long work_delay_jiffies;
> +	bool timestamp_enabled;
> +	bool timestamp_possible;
>  };
>
>  /**
> @@ -78,5 +91,12 @@ int ctucan_probe_common(struct device *dev, void __iomem
> *addr,
>
>  int ctucan_suspend(struct device *dev) __maybe_unused;
>  int ctucan_resume(struct device *dev) __maybe_unused;
> +int ctucan_runtime_resume(struct device *dev) __maybe_unused;
> +int ctucan_runtime_suspend(struct device *dev) __maybe_unused;
>
> +u64 ctucan_read_timestamp_cc_wrapper(const struct cyclecounter *cc);
> +u64 ctucan_read_timestamp_counter(struct ctucan_priv *priv);
> +void ctucan_skb_set_timestamp(struct ctucan_priv *priv, struct sk_buff
> *skb, u64 timestamp); +void ctucan_timestamp_init(struct ctucan_priv
> *priv);
> +void ctucan_timestamp_stop(struct ctucan_priv *priv);
>  #endif /*__CTUCANFD__*/
> diff --git a/drivers/net/can/ctucanfd/ctucanfd_base.c
> b/drivers/net/can/ctucanfd/ctucanfd_base.c index 3c18d028bd8c..ba1a27c62ff1
> 100644
> --- a/drivers/net/can/ctucanfd/ctucanfd_base.c
> +++ b/drivers/net/can/ctucanfd/ctucanfd_base.c
> @@ -18,6 +18,7 @@
>  
> ***************************************************************************
>***/
>
>  #include <linux/clk.h>
> +#include <linux/clocksource.h>
>  #include <linux/errno.h>
>  #include <linux/ethtool.h>
>  #include <linux/init.h>
> @@ -25,6 +26,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
> +#include <linux/math64.h>
>  #include <linux/module.h>
>  #include <linux/skbuff.h>
>  #include <linux/string.h>
> @@ -148,6 +150,27 @@ static void ctucan_write_txt_buf(struct ctucan_priv
> *priv, enum ctu_can_fd_can_r priv->write_reg(priv, buf_base + offset, val);
>  }
>
> +static inline u64 ctucan_concat_tstamp(u32 high, u32 low)
> +{
> +	return ((u64)high << 32) | ((u64)low);
> +}
> +
> +u64 ctucan_read_timestamp_counter(struct ctucan_priv *priv)
> +{
> +	u32 ts_low;
> +	u32 ts_high;
> +	u32 ts_high2;
> +
> +	ts_high = ctucan_read32(priv, CTUCANFD_TIMESTAMP_HIGH);
> +	ts_low = ctucan_read32(priv, CTUCANFD_TIMESTAMP_LOW);
> +	ts_high2 = ctucan_read32(priv, CTUCANFD_TIMESTAMP_HIGH);
> +
> +	if (ts_high2 != ts_high)
> +		ts_low = priv->read_reg(priv, CTUCANFD_TIMESTAMP_LOW);
> +
> +	return ctucan_concat_tstamp(ts_high2, ts_low) & priv->cc.mask;
> +}
> +
>  #define CTU_CAN_FD_TXTNF(priv) (!!FIELD_GET(REG_STATUS_TXNF,
> ctucan_read32(priv, CTUCANFD_STATUS))) #define CTU_CAN_FD_ENABLED(priv)
> (!!FIELD_GET(REG_MODE_ENA, ctucan_read32(priv, CTUCANFD_MODE)))
>
> @@ -640,12 +663,16 @@ static netdev_tx_t ctucan_start_xmit(struct sk_buff
> *skb, struct net_device *nde * @priv:	Pointer to CTU CAN FD's private data
>   * @cf:		Pointer to CAN frame struct
>   * @ffw:	Previously read frame format word
> + * @skb:	Pointer to buffer to store timestamp
>   *
>   * Note: Frame format word must be read separately and provided in 'ffw'.
>   */
> -static void ctucan_read_rx_frame(struct ctucan_priv *priv, struct
> canfd_frame *cf, u32 ffw) +static void ctucan_read_rx_frame(struct
> ctucan_priv *priv, struct canfd_frame *cf, +				 u32 ffw, u64 *timestamp)
>  {
>  	u32 idw;
> +	u32 tstamp_high;
> +	u32 tstamp_low;
>  	unsigned int i;
>  	unsigned int wc;
>  	unsigned int len;
> @@ -682,9 +709,10 @@ static void ctucan_read_rx_frame(struct ctucan_priv
> *priv, struct canfd_frame *c if (unlikely(len > wc * 4))
>  		len = wc * 4;
>
> -	/* Timestamp - Read and throw away */
> -	ctucan_read32(priv, CTUCANFD_RX_DATA);
> -	ctucan_read32(priv, CTUCANFD_RX_DATA);
> +	/* Timestamp */
> +	tstamp_low = ctucan_read32(priv, CTUCANFD_RX_DATA);
> +	tstamp_high = ctucan_read32(priv, CTUCANFD_RX_DATA);
> +	*timestamp = ctucan_concat_tstamp(tstamp_high, tstamp_low) &
> priv->cc.mask;
>
>  	/* Data */
>  	for (i = 0; i < len; i += 4) {
> @@ -713,6 +741,7 @@ static int ctucan_rx(struct net_device *ndev)
>  	struct net_device_stats *stats = &ndev->stats;
>  	struct canfd_frame *cf;
>  	struct sk_buff *skb;
> +	u64 timestamp;
>  	u32 ffw;
>
>  	if (test_bit(CTUCANFD_FLAG_RX_FFW_BUFFERED, &priv->drv_flags)) {
> @@ -736,7 +765,9 @@ static int ctucan_rx(struct net_device *ndev)
>  		return 0;
>  	}
>
> -	ctucan_read_rx_frame(priv, cf, ffw);
> +	ctucan_read_rx_frame(priv, cf, ffw, &timestamp);
> +	if (priv->timestamp_enabled)
> +		ctucan_skb_set_timestamp(priv, skb, timestamp);
>
>  	stats->rx_bytes += cf->len;
>  	stats->rx_packets++;
> @@ -906,6 +937,11 @@ static void ctucan_err_interrupt(struct net_device
> *ndev, u32 isr) if (skb) {
>  		stats->rx_packets++;
>  		stats->rx_bytes += cf->can_dlc;
> +		if (priv->timestamp_enabled) {
> +			u64 tstamp = ctucan_read_timestamp_counter(priv);
> +
> +			ctucan_skb_set_timestamp(priv, skb, tstamp);
> +		}
>  		netif_rx(skb);
>  	}
>  }
> @@ -951,6 +987,11 @@ static int ctucan_rx_poll(struct napi_struct *napi,
> int quota) cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
>  			stats->rx_packets++;
>  			stats->rx_bytes += cf->can_dlc;
> +			if (priv->timestamp_enabled) {
> +				u64 tstamp = ctucan_read_timestamp_counter(priv);
> +
> +				ctucan_skb_set_timestamp(priv, skb, tstamp);
> +			}
>  			netif_rx(skb);
>  		}
>
> @@ -1200,9 +1241,9 @@ static int ctucan_open(struct net_device *ndev)
>  	struct ctucan_priv *priv = netdev_priv(ndev);
>  	int ret;
>
> -	ret = pm_runtime_get_sync(priv->dev);
> +	ret = pm_runtime_resume_and_get(priv->dev);
>  	if (ret < 0) {
> -		netdev_err(ndev, "%s: pm_runtime_get failed(%d)\n",
> +		netdev_err(ndev, "%s: pm_runtime_resume_and_get failed(%d)\n",
>  			   __func__, ret);
>  		pm_runtime_put_noidle(priv->dev);
>  		return ret;
> @@ -1231,6 +1272,9 @@ static int ctucan_open(struct net_device *ndev)
>  		goto err_chip_start;
>  	}
>
> +	if (priv->timestamp_possible)
> +		ctucan_timestamp_init(priv);
> +
>  	netdev_info(ndev, "ctu_can_fd device registered\n");
>  	napi_enable(&priv->napi);
>  	netif_start_queue(ndev);
> @@ -1263,6 +1307,8 @@ static int ctucan_close(struct net_device *ndev)
>  	ctucan_chip_stop(ndev);
>  	free_irq(ndev->irq, ndev);
>  	close_candev(ndev);
> +	if (priv->timestamp_possible)
> +		ctucan_timestamp_stop(priv);
>
>  	pm_runtime_put(priv->dev);
>
> @@ -1282,9 +1328,9 @@ static int ctucan_get_berr_counter(const struct
> net_device *ndev, struct can_ber struct ctucan_priv *priv =
> netdev_priv(ndev);
>  	int ret;
>
> -	ret = pm_runtime_get_sync(priv->dev);
> +	ret = pm_runtime_resume_and_get(priv->dev);
>  	if (ret < 0) {
> -		netdev_err(ndev, "%s: pm_runtime_get failed(%d)\n", __func__, ret);
> +		netdev_err(ndev, "%s: pm_runtime_resume_and_get failed(%d)\n", __func__,
> ret); pm_runtime_put_noidle(priv->dev);
>  		return ret;
>  	}
> @@ -1295,15 +1341,83 @@ static int ctucan_get_berr_counter(const struct
> net_device *ndev, struct can_ber return 0;
>  }
>
> +static int ctucan_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
> +{
> +	struct ctucan_priv *priv = netdev_priv(dev);
> +	struct hwtstamp_config cfg;
> +
> +	if (!priv->timestamp_possible)
> +		return -EOPNOTSUPP;
> +
> +	if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
> +		return -EFAULT;
> +
> +	if (cfg.flags)
> +		return -EINVAL;
> +
> +	if (cfg.rx_filter == HWTSTAMP_FILTER_NONE && cfg.tx_type ==
> HWTSTAMP_TX_OFF) { +		priv->timestamp_enabled = false;
> +		return 0;
> +	} else if (cfg.rx_filter == HWTSTAMP_FILTER_ALL && cfg.tx_type ==
> HWTSTAMP_TX_ON) { +		priv->timestamp_enabled = true;
> +		return 0;
> +	} else {
> +		return -ERANGE;
> +	}
> +}
> +
> +static int ctucan_hwtstamp_get(struct net_device *dev, struct ifreq *ifr)
> +{
> +	struct ctucan_priv *priv = netdev_priv(dev);
> +	struct hwtstamp_config cfg;
> +
> +	if (!priv->timestamp_possible)
> +		return -EOPNOTSUPP;
> +
> +	cfg.flags = 0;
> +	cfg.tx_type = priv->timestamp_enabled ? HWTSTAMP_TX_ON : HWTSTAMP_TX_OFF;
> +	cfg.rx_filter = priv->timestamp_enabled ? HWTSTAMP_FILTER_ALL :
> HWTSTAMP_FILTER_NONE; +
> +	return copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)) ? -EFAULT : 0;
> +}
> +
> +static int ctucan_ioctl(struct net_device *dev, struct ifreq *ifr, int
> cmd) +{
> +	switch (cmd) {
> +	case SIOCSHWTSTAMP:
> +		return ctucan_hwtstamp_set(dev, ifr);
> +	case SIOCGHWTSTAMP:
> +		return ctucan_hwtstamp_get(dev, ifr);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int ctucan_ethtool_get_ts_info(struct net_device *ndev,
> +				      struct ethtool_ts_info *info)
> +{
> +	struct ctucan_priv *priv = netdev_priv(ndev);
> +
> +	if (!priv->timestamp_possible)
> +		return ethtool_op_get_ts_info(ndev, info);
> +
> +	can_ethtool_op_get_ts_info_hwts(ndev, info);
> +	info->rx_filters |= BIT(HWTSTAMP_FILTER_NONE);
> +	info->tx_types |= BIT(HWTSTAMP_TX_OFF);
> +
> +	return 0;
> +}
> +
>  static const struct net_device_ops ctucan_netdev_ops = {
>  	.ndo_open	= ctucan_open,
>  	.ndo_stop	= ctucan_close,
>  	.ndo_start_xmit	= ctucan_start_xmit,
>  	.ndo_change_mtu	= can_change_mtu,
> +	.ndo_eth_ioctl	= ctucan_ioctl,
>  };
>
>  static const struct ethtool_ops ctucan_ethtool_ops = {
> -	.get_ts_info = ethtool_op_get_ts_info,
> +	.get_ts_info = ctucan_ethtool_get_ts_info,
>  };
>
>  int ctucan_suspend(struct device *dev)
> @@ -1338,12 +1452,42 @@ int ctucan_resume(struct device *dev)
>  }
>  EXPORT_SYMBOL(ctucan_resume);
>
> +int ctucan_runtime_suspend(struct device *dev)
> +{
> +	struct net_device *ndev = dev_get_drvdata(dev);
> +	struct ctucan_priv *priv = netdev_priv(ndev);
> +
> +	if (!IS_ERR_OR_NULL(priv->timestamp_clk))
> +		clk_disable_unprepare(priv->timestamp_clk);

How is it with the the other common clock used for memory space
IO bus and CAN bittimmig? 

+	if (!IS_ERR_OR_NULL(priv->can_clk))
+		clk_disable_unprepare(priv->can_clk);

Question is even if there should be prepare or disable
only.

> +	return 0;
> +}
> +EXPORT_SYMBOL(ctucan_runtime_suspend);
> +
> +int ctucan_runtime_resume(struct device *dev)
> +{
> +	struct net_device *ndev = dev_get_drvdata(dev);
> +	struct ctucan_priv *priv = netdev_priv(ndev);
> +	int ret;
> +

Then equivalent there ???

+	if (!IS_ERR_OR_NULL(priv->can_clk)) {
+		ret = clk_prepare_enable(priv->can_clk);
+		if (ret) {
+			dev_err(dev, "Cannot enable core clock: %d\n", ret);
+			return ret;
+		}
+	}

In the general, we have discussion with Marc about possibility unprepared
and again prepared clocks there could lead to the frequency change
when some wakeup order etc.. does not correspond to the initial drivers
and devices enumeration order. This is generic problem and I am not prepared
to solve and test it in this round. But may it be clock should be only
disabled over standby or there should be run full recalculation of bitimming
and even timestamps...

> +	if (!IS_ERR_OR_NULL(priv->timestamp_clk)) {
> +		ret = clk_prepare_enable(priv->timestamp_clk);
> +		if (ret) {
> +			dev_err(dev, "Cannot enable timestamping clock: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +	return 0;
> +}
> +EXPORT_SYMBOL(ctucan_runtime_resume);
> +
>  int ctucan_probe_common(struct device *dev, void __iomem *addr, int irq,
> unsigned int ntxbufs, unsigned long can_clk_rate, int pm_enable_call,
>  			void (*set_drvdata_fnc)(struct device *dev, struct net_device *ndev))
>  {
>  	struct ctucan_priv *priv;
>  	struct net_device *ndev;
> +	u32 timestamp_freq = 0;
> +	u32 timestamp_bit_size = 0;
>  	int ret;
>
>  	/* Create a CAN device instance */
> @@ -1373,6 +1517,7 @@ int ctucan_probe_common(struct device *dev, void
> __iomem *addr, int irq, unsigne
>
>  					| CAN_CTRLMODE_FD_NON_ISO
>  					| CAN_CTRLMODE_ONE_SHOT;
>
>  	priv->mem_base = addr;
> +	priv->timestamp_possible = true;
>
>  	/* Get IRQ for the device */
>  	ndev->irq = irq;
> @@ -1386,27 +1531,39 @@ int ctucan_probe_common(struct device *dev, void
> __iomem *addr, int irq, unsigne
>
>  	/* Getting the can_clk info */
>  	if (!can_clk_rate) {
> -		priv->can_clk = devm_clk_get(dev, NULL);
> +		priv->can_clk = devm_clk_get_optional(dev, "core-clk");
> +		if (!priv->can_clk)
> +			/* For compatibility with (older) device trees without clock-names */
> +			priv->can_clk = devm_clk_get(dev, NULL);
>  		if (IS_ERR(priv->can_clk)) {
> -			dev_err(dev, "Device clock not found.\n");
> +			dev_err(dev, "Device clock not found: %pe.\n", priv->can_clk);
>  			ret = PTR_ERR(priv->can_clk);
>  			goto err_free;
>  		}

Not problem in our case, FPGA clocks are prepared and running because in another case
whole AXI, APB etc accesses would stuck the core, but the prepare should be there
as well??? 

+		clk_prepare_enable(priv->timestamp_clk);

>  		can_clk_rate = clk_get_rate(priv->can_clk);
>  	}
>
> +	/* If it's a platform device - get the timestamping clock */
> +	if (pm_enable_call) {
> +		priv->timestamp_clk = devm_clk_get(dev, "ts-clk");
> +		if (IS_ERR(priv->timestamp_clk)) {
> +			/* Take the core clock instead */
> +			dev_info(dev, "Failed to get ts clk\nl");
> +			priv->timestamp_clk = priv->can_clk;
> +		}
> +		clk_prepare_enable(priv->timestamp_clk);

I hope that prepare twice the same clock when "core-clk" is used
instead of separate "ts-clk" is not problem and that enables and prepares
are counted.

> +		timestamp_freq = clk_get_rate(priv->timestamp_clk);
> +	} else {
> +		/* PCI device: assume tstamp freq is equal to bus clk rate */
> +		timestamp_freq = can_clk_rate;
> +	}
> +
>  	priv->write_reg = ctucan_write32_le;
>  	priv->read_reg = ctucan_read32_le;
>
> +	pm_runtime_get_noresume(dev);
>  	if (pm_enable_call)
>  		pm_runtime_enable(dev);
> -	ret = pm_runtime_get_sync(dev);
> -	if (ret < 0) {
> -		netdev_err(ndev, "%s: pm_runtime_get failed(%d)\n",
> -			   __func__, ret);
> -		pm_runtime_put_noidle(priv->dev);
> -		goto err_pmdisable;
> -	}
>
>  	/* Check for big-endianity and set according IO-accessors */
>  	if ((ctucan_read32(priv, CTUCANFD_DEVICE_ID) & 0xFFFF) != CTUCANFD_ID) {
> @@ -1425,6 +1582,49 @@ int ctucan_probe_common(struct device *dev, void
> __iomem *addr, int irq, unsigne
>
>  	priv->can.clock.freq = can_clk_rate;
>
> +	/* Obtain timestamping counter bit size */
> +	timestamp_bit_size = FIELD_GET(REG_ERR_CAPT_TS_BITS,
> +				       ctucan_read32(priv, CTUCANFD_ERR_CAPT));
> +
> +	/* The register value is actually bit_size - 1 */
> +	if (timestamp_bit_size) {
> +		timestamp_bit_size += 1;
> +	} else {
> +		/* For 2.x versions of the IP core, we will assume 64-bit counter
> +		 * if there was a 0 in the register.
> +		 */
> +		u32 version_reg = ctucan_read32(priv, CTUCANFD_DEVICE_ID);
> +		u32 major = FIELD_GET(REG_DEVICE_ID_VER_MAJOR, version_reg);
> +
> +		if (major == 2)
> +			timestamp_bit_size = 64;
> +		else
> +			priv->timestamp_possible = false;
> +	}
> +
> +	/* Setup conversion constants and work delay */
> +	priv->cc.mask = CYCLECOUNTER_MASK(timestamp_bit_size);
> +	if (priv->timestamp_possible) {
> +		u64 max_cycles;
> +		u64 work_delay_ns;
> +		u32 maxsec = min_t(u32, CTUCANFD_MAX_WORK_DELAY_SEC,
> +				   div_u64(priv->cc.mask, timestamp_freq));
> +
> +		priv->cc.read = ctucan_read_timestamp_cc_wrapper;
> +		clocks_calc_mult_shift(&priv->cc.mult, &priv->cc.shift,
> +				       timestamp_freq, NSEC_PER_SEC, maxsec);
> +
> +		/* shortened copy of clocks_calc_max_nsecs() */
> +		max_cycles = div_u64(ULLONG_MAX, priv->cc.mult);
> +		max_cycles = min(max_cycles, priv->cc.mask);
> +		work_delay_ns = clocksource_cyc2ns(max_cycles, priv->cc.mult,
> +						   priv->cc.shift) >> 1;
> +		priv->work_delay_jiffies = nsecs_to_jiffies(work_delay_ns);
> +
> +		if (priv->work_delay_jiffies == 0)
> +			priv->timestamp_possible = false;
> +	}
> +
>  	netif_napi_add(ndev, &priv->napi, ctucan_rx_poll, NAPI_POLL_WEIGHT);
>
>  	ret = register_candev(ndev);
> @@ -1442,7 +1642,6 @@ int ctucan_probe_common(struct device *dev, void
> __iomem *addr, int irq, unsigne
>
>  err_deviceoff:
>  	pm_runtime_put(priv->dev);
> -err_pmdisable:
>  	if (pm_enable_call)
>  		pm_runtime_disable(dev);
>  err_free:


How is this in the driver remove?

The device managed devm_clk_get takes care about clock release
(clk_put)

https://elixir.bootlin.com/linux/latest/source/drivers/clk/clk-devres.c#L12  

But I expect that clk_put does not take care about disable
and unprepare which has to be in ballance to the calls inside probe.

We probably will need something like

int ctucan_remove_common(struct ctucan_priv *priv)

with

	if (!IS_ERR_OR_NULL(priv->timestamp_clk))
		clk_disable_unprepare(priv->timestamp_clk);

	if (!IS_ERR_OR_NULL(priv->can_clk))
		clk_disable_unprepare(priv->can_clk);


called from the both

  ctucan_platform_remove(struct platform_device *pdev)
  ctucan_pci_remove(struct pci_dev *pdev)

> diff --git a/drivers/net/can/ctucanfd/ctucanfd_pci.c
> b/drivers/net/can/ctucanfd/ctucanfd_pci.c index 8f2956a8ae43..bdb7cf789776
> 100644
> --- a/drivers/net/can/ctucanfd/ctucanfd_pci.c
> +++ b/drivers/net/can/ctucanfd/ctucanfd_pci.c
> @@ -271,7 +271,10 @@ static void ctucan_pci_remove(struct pci_dev *pdev)
>  	kfree(bdata);
>  }
>
> -static SIMPLE_DEV_PM_OPS(ctucan_pci_pm_ops, ctucan_suspend,
> ctucan_resume); +static const struct dev_pm_ops ctucan_pci_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(ctucan_suspend, ctucan_resume)
> +	SET_RUNTIME_PM_OPS(ctucan_runtime_suspend, ctucan_runtime_resume, NULL)
> +};
>
>  static const struct pci_device_id ctucan_pci_tbl[] = {
>  	{PCI_DEVICE_DATA(TEDIA, CTUCAN_VER21,
> diff --git a/drivers/net/can/ctucanfd/ctucanfd_platform.c
> b/drivers/net/can/ctucanfd/ctucanfd_platform.c index
> 89d54c2151e1..1b2052aec2ab 100644
> --- a/drivers/net/can/ctucanfd/ctucanfd_platform.c
> +++ b/drivers/net/can/ctucanfd/ctucanfd_platform.c
> @@ -104,7 +104,10 @@ static int ctucan_platform_remove(struct
> platform_device *pdev) return 0;
>  }
>
> -static SIMPLE_DEV_PM_OPS(ctucan_platform_pm_ops, ctucan_suspend,
> ctucan_resume); +static const struct dev_pm_ops ctucan_platform_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(ctucan_suspend, ctucan_resume)
> +	SET_RUNTIME_PM_OPS(ctucan_runtime_suspend, ctucan_runtime_resume, NULL)
> +};
>
>  /* Match table for OF platform binding */
>  static const struct of_device_id ctucan_of_match[] = {
> diff --git a/drivers/net/can/ctucanfd/ctucanfd_timestamp.c
> b/drivers/net/can/ctucanfd/ctucanfd_timestamp.c new file mode 100644
> index 000000000000..77e461d1962d
> --- /dev/null
> +++ b/drivers/net/can/ctucanfd/ctucanfd_timestamp.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*************************************************************************
>****** + *
> + * CTU CAN FD IP Core
> + *
> + * Copyright (C) 2022 Matej Vasilevski <matej.vasilevski@...nam.cz> FEE
> CTU + *
> + * Project advisors:
> + *     Jiri Novak <jnovak@....cvut.cz>
> + *     Pavel Pisa <pisa@....felk.cvut.cz>
> + *
> + * Department of Measurement         (http://meas.fel.cvut.cz/)
> + * Faculty of Electrical Engineering (http://www.fel.cvut.cz)
> + * Czech Technical University        (http://www.cvut.cz/)
> +
> ***************************************************************************
>***/ +
> +#include "linux/spinlock.h"
> +#include <linux/bitops.h>
> +#include <linux/clocksource.h>
> +#include <linux/math64.h>
> +#include <linux/timecounter.h>
> +#include <linux/workqueue.h>
> +
> +#include "ctucanfd.h"
> +#include "ctucanfd_kregs.h"
> +
> +u64 ctucan_read_timestamp_cc_wrapper(const struct cyclecounter *cc)
> +{
> +	struct ctucan_priv *priv;
> +
> +	priv = container_of(cc, struct ctucan_priv, cc);
> +	return ctucan_read_timestamp_counter(priv);
> +}
> +
> +static void ctucan_timestamp_work(struct work_struct *work)
> +{
> +	struct delayed_work *delayed_work = to_delayed_work(work);
> +	struct ctucan_priv *priv = container_of(delayed_work, struct ctucan_priv,
> timestamp); +	unsigned long flags;
> +
> +	spin_lock_irqsave(&priv->tc_lock, flags);
> +	timecounter_read(&priv->tc);
> +	spin_unlock_irqrestore(&priv->tc_lock, flags);
> +	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
> +}
> +
> +void ctucan_skb_set_timestamp(struct ctucan_priv *priv, struct sk_buff
> *skb, u64 timestamp) +{
> +	struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
> +	u64 ns;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&priv->tc_lock, flags);
> +	ns = timecounter_cyc2time(&priv->tc, timestamp);
> +	spin_unlock_irqrestore(&priv->tc_lock, flags);
> +	hwtstamps->hwtstamp = ns_to_ktime(ns);
> +}
> +
> +void ctucan_timestamp_init(struct ctucan_priv *priv)
> +{
> +	spin_lock_init(&priv->tc_lock);
> +	timecounter_init(&priv->tc, &priv->cc, ktime_get_real_ns());
> +	INIT_DELAYED_WORK(&priv->timestamp, ctucan_timestamp_work);
> +	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
> +}
> +
> +void ctucan_timestamp_stop(struct ctucan_priv *priv)
> +{
> +	cancel_delayed_work_sync(&priv->timestamp);
> +}

Best wishes and thanks for suggestions and review
in advance,


                Pavel

-- 
                Pavel Pisa
    phone:      +420 603531357
    e-mail:     pisa@....felk.cvut.cz
    Department of Control Engineering FEE CVUT
    Karlovo namesti 13, 121 35, Prague 2
    university: http://control.fel.cvut.cz/
    personal:   http://cmp.felk.cvut.cz/~pisa
    projects:   https://www.openhub.net/accounts/ppisa
    CAN related:http://canbus.pages.fel.cvut.cz/
    RISC-V education: https://comparch.edu.cvut.cz/
    Open Technologies Research Education and Exchange Services
    https://gitlab.fel.cvut.cz/otrees/org/-/wikis/home

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