Re: [PATCH v3 net-next 04/15] ptp: netc: add NETC V4 Timer PTP driver support

[Vladimir Oltean <vladimir.oltean@nxp.com>]

On Tue, Aug 12, 2025 at 05:46:23PM +0800, Wei Fang wrote:
> +int netc_timer_get_phc_index(struct pci_dev *timer_pdev)
> +{
> +	struct netc_timer *priv;
> +
> +	if (!timer_pdev)
> +		return -ENODEV;
> +
> +	priv = pci_get_drvdata(timer_pdev);
> +	if (!priv)
> +		return -EINVAL;
> +
> +	return priv->phc_index;
> +}
> +EXPORT_SYMBOL_GPL(netc_timer_get_phc_index);
...
> @@ -16,4 +17,13 @@ static inline void netc_write(void __iomem *reg, u32 val)
>  	iowrite32(val, reg);
>  }
>  
> +#if IS_ENABLED(CONFIG_PTP_NETC_V4_TIMER)
> +int netc_timer_get_phc_index(struct pci_dev *timer_pdev);
> +#else
> +static inline int netc_timer_get_phc_index(struct pci_dev *timer_pdev)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +

I was expecting that with the generic ptp-timer phandle you'd also offer
a generic mechanism of retrieving the PHC index, instead of cooking up a
custom API convention between the NETC MAC and the NETC timer.

Something like below, completely untested:

struct ptp_clock_fwnode_match {
	struct fwnode_handle *fwnode;
	struct ptp_clock *clock;
};

static int ptp_clock_fwnode_match(struct device *dev, void *data)
{
	struct ptp_clock_fwnode_match *match = data;

	if (!dev->parent || dev_fwnode(dev->parent) != match->fwnode)
		return 0;

	match->clock = dev_get_drvdata(dev);
	return 1;
}

static struct ptp_clock *ptp_clock_find_by_fwnode(struct fwnode_handle *fwnode)
{
	struct ptp_clock_fwnode_match match = { .fwnode = fwnode };

	class_for_each_device(&ptp_class, NULL, &match, ptp_clock_fwnode_match);

	return match.clock;
}

int ptp_clock_index_by_fwnode_handle(struct fwnode_handle *fwnode)
{
	struct fwnode_handle *ptp_fwnode;
	struct ptp_clock *clock;
	int phc_index;

	ptp_fwnode = fwnode_find_reference(fwnode, "ptp-timer", 0);
	if (!ptp_fwnode)
		return -1;

	clock = ptp_clock_find_by_fwnode(ptp_fwnode);
	fwnode_handle_put(ptp_fwnode);
	if (!clock)
		return -1;

	phc_index = ptp_clock_index(clock);
	put_device(&clock->dev);

	return phc_index;
}
EXPORT_SYMBOL_GPL(ptp_clock_index_by_fwnode_handle);