From: Wojciech Drewek <wojciech.dre...@intel.com>
Date: Wed, 21 Aug 2024 14:15:31 +0200
> From: Jacob Keller <jacob.e.kel...@intel.com>
>
> Add the iavf_ptp.c file and fill it in with a skeleton framework to
> allow registering the PTP clock device.
> Add implementation of helper functions to check if a PTP capability
> is supported and handle change in PTP capabilities.
> Enabling virtual clock would be possible, though it would probably
> perform poorly due to the lack of direct time access.
[...]
> +/**
> + * iavf_ptp_register_clock - Register a new PTP for userspace
> + * @adapter: private adapter structure
> + *
> + * Allocate and register a new PTP clock device if necessary.
> + *
> + * Return: 0 if success, error otherwise
Period ('.') at the end is desired at the end of kdoc.
> + */
> +static int iavf_ptp_register_clock(struct iavf_adapter *adapter)
> +{
> + struct ptp_clock_info *ptp_info = &adapter->ptp.info;
> + struct device *dev = &adapter->pdev->dev;
> +
> + memset(ptp_info, 0, sizeof(*ptp_info));
Is this needed? adapter is allocated using kzalloc() I think?
> +
> + snprintf(ptp_info->name, sizeof(ptp_info->name), "%s-%s-clk",
> + dev_driver_string(dev), dev_name(dev));
dev_driver_string() can be just KBUILD_MODNAME when it's called inside
the actual module. It's mostly used when you need to get a module name
from a different module or core kernel code.
> + ptp_info->owner = THIS_MODULE;
> +
> + adapter->ptp.clock = ptp_clock_register(ptp_info, dev);
> + if (IS_ERR(adapter->ptp.clock)) {
> + adapter->ptp.clock = NULL;
> +
> + return PTR_ERR(adapter->ptp.clock);
Braino here.
You first set ptp.clock to %NULL and then return PTR_ERR(ptp.clock).
IOW, this error path will always return 0.
I usually use temporary variables to avoid this.
clock = ptp_clock_register(ptp_info, dev);
if (IS_ERR(clock))
return PTR_ERR(clock);
adapter->ptp.clock = clock;
> + }
> +
> + dev_dbg(&adapter->pdev->dev, "PTP clock %s registered\n",
> + adapter->ptp.info.name);
> +
> + return 0;
> +}
> +
> +/**
> + * iavf_ptp_init - Initialize PTP support if capability was negotiated
> + * @adapter: private adapter structure
> + *
> + * Initialize PTP functionality, based on the capabilities that the PF has
> + * enabled for this VF.
> + */
> +void iavf_ptp_init(struct iavf_adapter *adapter)
> +{
> + int err;
> +
> + if (!iavf_ptp_cap_supported(adapter, VIRTCHNL_1588_PTP_CAP_READ_PHC)) {
> + pci_warn(adapter->pdev,
> + "Device does not have PTP clock support\n");
I think it's pci_notice() or even pci_dbg(). A device can miss PTP
clock, but it's not a failure. _warn() is when something went wrong, but
not as wrong as _err() :D
> + return;
> + }
> +
> + err = iavf_ptp_register_clock(adapter);
> + if (err) {
> + pci_err(adapter->pdev,
> + "Failed to register PTP clock device (%p)\n",
> + ERR_PTR(err));
> + return;
> + }
Why does this function return void if there's an error path? To make
sure the driver works even if PTP fails to register? But I think it's
better to bail out if something failed than to work without certain
functionality?
> +
> + adapter->ptp.initialized = true;
> +}
> +
> +/**
> + * iavf_ptp_release - Disable PTP support
> + * @adapter: private adapter structure
> + *
> + * Release all PTP resources that were previously initialized.
> + */
> +void iavf_ptp_release(struct iavf_adapter *adapter)
> +{
> + adapter->ptp.initialized = false;
> +
> + if (!IS_ERR_OR_NULL(adapter->ptp.clock)) {
Since you always assign clock to %NULL when the initialization failed,
this could be just
if (adapter->ptp.clock)
> + dev_dbg(&adapter->pdev->dev, "removing PTP clock %s\n",
> + adapter->ptp.info.name);
pci_dbg()
> + ptp_clock_unregister(adapter->ptp.clock);
> + adapter->ptp.clock = NULL;
> + }
...but I'd invert the condition to avoid +1 indent level.
if (!adapter->ptp.clock)
return;
pci_dbg() ...
> +}
> +
> +/**
> + * iavf_ptp_process_caps - Handle change in PTP capabilities
> + * @adapter: private adapter structure
> + *
> + * Handle any state changes necessary due to change in PTP capabilities, such
> + * as after a device reset or change in configuration from the PF.
> + */
> +void iavf_ptp_process_caps(struct iavf_adapter *adapter)
> +{
> + bool read_phc = iavf_ptp_cap_supported(adapter,
> + VIRTCHNL_1588_PTP_CAP_READ_PHC);
Maybe split the declaration and initialization to avoid line break? My
editor says it would fit in 80 if you make the variable name shorter,
e.g. 'phc'.
> +
> + /* Check if the device gained or lost necessary access to support the
> + * PTP hardware clock. If so, driver must respond appropriately by
> + * creating or destroying the PTP clock device.
> + */
> + if (adapter->ptp.initialized && !read_phc)
> + iavf_ptp_release(adapter);
> + else if (!adapter->ptp.initialized && read_phc)
> + iavf_ptp_init(adapter);
> +}
Thanks,
Olek
