linux-kernel - Re: [PATCH 2/5] platform/x86/intel: Move intel

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Message-ID: <668f263e1d2606ad7485c40ce41933300ec4b8a3.camel@linux.intel.com>
Date:   Wed, 06 Oct 2021 13:58:22 -0700
From:   "David E. Box" <david.e.box@...ux.intel.com>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     lee.jones@...aro.org, hdegoede@...hat.com, mgross@...ux.intel.com,
        bhelgaas@...gle.com, gregkh@...uxfoundation.org,
        andriy.shevchenko@...ux.intel.com, srinivas.pandruvada@...el.com,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/5] platform/x86/intel: Move intel_pmt from MFD to
 Auxiliary Bus

On Wed, 2021-10-06 at 11:58 +0300, Leon Romanovsky wrote:
> On Thu, Sep 30, 2021 at 06:28:12PM -0700, David E. Box wrote:
> > Intel Platform Monitoring Technology (PMT) support is indicated by presence
> > of an Intel defined PCIe DVSEC structure with a PMT ID. However DVSEC
> > structures may also be used by Intel to indicate support for other
> > capabilities unrelated to PMT.  The Out Of Band Management Services Module
> > (OOBMSM) is an example of a device that can have both PMT and non-PMT
> > capabilities. In order to support these capabilities it is necessary to
> > modify the intel_pmt driver to handle the creation of platform devices more
> > generically. To that end the following changes are made.
> > 
> > Convert the driver and child drivers from MFD to the Auxiliary Bus. This
> > architecture is more suitable anyway since the driver partitions a
> > multifunctional PCIe device. This also moves the driver out of the MFD
> > subsystem and into platform/x86/intel.
> > 
> > Before, devices were named by their capability (e.g. pmt_telemetry).
> > Instead, generically name them by their capability ID (e.g.
> > intel_extended_cap.2). This allows the IDs to be created automatically,
> > minimizing the code needed to support future capabilities. However, to
> > ensure that unsupported devices aren't created, use an allow list to
> > specify supported capabilities. Along these lines, rename the driver from
> > intel_pmt to intel_extended_caps to better reflect the purpose.
> > 
> > Signed-off-by: David E. Box <david.e.box@...ux.intel.com>
> > ---
> > 
> > V1:     New patch. However incorporates some elements of [1] which was
> >         dropped. Namely enumerating features generically and creating an
> >         allow list. Also cleans up probe by moving some code to functions
> >         and using a bool instead of an int to track whether a device was
> >         added.
> > 
> > [1] https://lore.kernel.org/all/20210922213007.2738388-3-david.e.box@linux.intel.com/
> 
> <...>
> 
> > +static int extended_caps_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > +{
> > +       struct extended_caps_platform_info *info;
> > +       bool have_devices = false;
> > +       unsigned long quirks = 0;
> > +       int ret;
> > +
> > +       ret = pcim_enable_device(pdev);
> > +       if (ret)
> > +               return ret;
> > +
> > +       info = (struct extended_caps_platform_info *)id->driver_data;
> 
> pci_get_drvdata() in all places and no need to cast void *.

This is coming from the id not the pdev. The data here is type kernel_ulong_t.

> 
> > +       if (info)
> > +               quirks = info->quirks;
> > +
> > +       have_devices |= extended_caps_walk_dvsec(pdev, quirks);
> > +
> > +       if (info && (info->quirks & EXT_CAPS_QUIRK_NO_DVSEC))
> > +               have_devices |= extended_caps_walk_header(pdev, quirks, info->capabilities);
> > +
> > +       if (!have_devices)
> > +               return -ENODEV;
> > +
> > +       return 0;
> > +}
> 
> <...>
> 
> > -static struct platform_driver pmt_telem_driver = {
> > -       .driver = {
> > -               .name   = TELEM_DEV_NAME,
> > -       },
> > -       .remove = pmt_telem_remove,
> > -       .probe  = pmt_telem_probe,
> > +static const struct auxiliary_device_id pmt_telem_aux_id_table[] = {
> > +       { .name = "intel_extended_caps.2", },
> 
> Why "2" in the name?

This is being changed to a string for the next version after similar comment. Thanks.

David

> 
> Thanks
> 
> > +       {},
> > +};
> > +MODULE_DEVICE_TABLE(auxiliary, pmt_telem_aux_id_table);
> > +
> > +static struct auxiliary_driver pmt_telem_aux_driver = {
> > +       .id_table       = pmt_telem_aux_id_table,
> > +       .remove         = pmt_telem_remove,
> > +       .probe          = pmt_telem_probe,
> >  };
> >