Re: [PATCH v4 net-next 03/15] ptp: add helpers to get the phc_index by of_node or dev

[Frank Li <Frank.li@nxp.com>]

On Tue, Aug 19, 2025 at 08:36:08PM +0800, Wei Fang wrote:
> Some Ethernet controllers do not have an integrated PTP timer function.
> Instead, the PTP timer is a separated device and provides PTP hardware
> clock to the Ethernet controller to use. Therefore, the Ethernet
> controller driver needs to obtain the PTP clock's phc_index in its
> ethtool_ops::get_ts_info(). Currently, most drivers implement this in
> the following ways.
>
> 1. The PTP device driver adds a custom API and exports it to the Ethernet
> controller driver.
> 2. The PTP device driver adds private data to its device structure. So
> the private data structure needs to be exposed to the Ethernet controller
> driver.
>
> When registering the ptp clock, ptp_clock_register() always saves the
> ptp_clock pointer to the private data of ptp_clock::dev. Therefore, as
> long as ptp_clock::dev is obtained, the phc_index can be obtained. So
> the following generic APIs can be added to the ptp driver to obtain the
> phc_index.
>
> 1. ptp_clock_index_by_dev(): Obtain the phc_index by the device pointer
> of the PTP device.
> 2.ptp_clock_index_by_of_node(): Obtain the phc_index by the of_node
> pointer of the PTP device.
>
> Also, we can add another API like ptp_clock_index_by_fwnode() to get the
> phc_index by fwnode of PTP device. However, this API is not used in this
> patch set, so it is better to add it when needed.

Needn't this paragraph.

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>
> Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Signed-off-by: Wei Fang <wei.fang@nxp.com>
>
> ---
> v4 changes:
> New patch
> ---
>  drivers/ptp/ptp_clock.c          | 53 ++++++++++++++++++++++++++++++++
>  include/linux/ptp_clock_kernel.h | 22 +++++++++++++
>  2 files changed, 75 insertions(+)
>
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index 1cc06b7cb17e..2b0fd62a17ef 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -11,6 +11,7 @@
>  #include <linux/module.h>
>  #include <linux/posix-clock.h>
>  #include <linux/pps_kernel.h>
> +#include <linux/property.h>
>  #include <linux/slab.h>
>  #include <linux/syscalls.h>
>  #include <linux/uaccess.h>
> @@ -477,6 +478,58 @@ int ptp_clock_index(struct ptp_clock *ptp)
>  }
>  EXPORT_SYMBOL(ptp_clock_index);
>
> +static int ptp_clock_of_node_match(struct device *dev, const void *data)
> +{
> +	const struct device_node *parent_np = data;
> +
> +	return (dev->parent && dev_of_node(dev->parent) == parent_np);
> +}
> +
> +int ptp_clock_index_by_of_node(struct device_node *np)
> +{
> +	struct ptp_clock *ptp;
> +	struct device *dev;
> +	int phc_index;
> +
> +	dev = class_find_device(&ptp_class, NULL, np,
> +				ptp_clock_of_node_match);
> +	if (!dev)
> +		return -1;
> +
> +	ptp = dev_get_drvdata(dev);
> +	phc_index = ptp_clock_index(ptp);
> +	put_device(dev);
> +
> +	return phc_index;
> +}
> +EXPORT_SYMBOL_GPL(ptp_clock_index_by_of_node);
> +
> +static int ptp_clock_dev_match(struct device *dev, const void *data)
> +{
> +	const struct device *parent = data;
> +
> +	return dev->parent == parent;
> +}
> +
> +int ptp_clock_index_by_dev(struct device *parent)
> +{
> +	struct ptp_clock *ptp;
> +	struct device *dev;
> +	int phc_index;
> +
> +	dev = class_find_device(&ptp_class, NULL, parent,
> +				ptp_clock_dev_match);
> +	if (!dev)
> +		return -1;
> +
> +	ptp = dev_get_drvdata(dev);
> +	phc_index = ptp_clock_index(ptp);
> +	put_device(dev);
> +
> +	return phc_index;
> +}
> +EXPORT_SYMBOL_GPL(ptp_clock_index_by_dev);
> +
>  int ptp_find_pin(struct ptp_clock *ptp,
>  		 enum ptp_pin_function func, unsigned int chan)
>  {
> diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
> index 3d089bd4d5e9..7dd7951b23d5 100644
> --- a/include/linux/ptp_clock_kernel.h
> +++ b/include/linux/ptp_clock_kernel.h
> @@ -360,6 +360,24 @@ extern void ptp_clock_event(struct ptp_clock *ptp,
>
>  extern int ptp_clock_index(struct ptp_clock *ptp);
>
> +/**
> + * ptp_clock_index_by_of_node() - obtain the device index of
> + * a PTP clock based on the PTP device of_node
> + *
> + * @np:    The device of_node pointer of the PTP device.
> + * Return: The PHC index on success or -1 on failure.
> + */
> +int ptp_clock_index_by_of_node(struct device_node *np);
> +
> +/**
> + * ptp_clock_index_by_dev() - obtain the device index of
> + * a PTP clock based on the PTP device.
> + *
> + * @parent:    The parent device (PTP device) pointer of the PTP clock.
> + * Return: The PHC index on success or -1 on failure.
> + */
> +int ptp_clock_index_by_dev(struct device *parent);
> +
>  /**
>   * ptp_find_pin() - obtain the pin index of a given auxiliary function
>   *
> @@ -425,6 +443,10 @@ static inline void ptp_clock_event(struct ptp_clock *ptp,
>  { }
>  static inline int ptp_clock_index(struct ptp_clock *ptp)
>  { return -1; }
> +static inline int ptp_clock_index_by_of_node(struct device_node *np)
> +{ return -1; }
> +static inline int ptp_clock_index_by_dev(struct device *parent)
> +{ return -1; }
>  static inline int ptp_find_pin(struct ptp_clock *ptp,
>  			       enum ptp_pin_function func, unsigned int chan)
>  { return -1; }
> --
> 2.34.1
>