linux-kernel - RE: [PATCH v2 08/27] ocxl: Save the device serial number in ocxl

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Date:   Wed, 19 Feb 2020 15:03:11 +1100
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Keith Busch <keith.busch@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kurz <groug@...d.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: RE: [PATCH v2 08/27] ocxl: Save the device serial number in ocxl_fn

On Mon, 2020-02-03 at 12:53 +0000, Jonathan Cameron wrote:
> On Tue, 3 Dec 2019 14:46:36 +1100
> Alastair D'Silva <alastair@....ibm.com> wrote:
> 
> > From: Alastair D'Silva <alastair@...ilva.org>
> > 
> > This patch retrieves the serial number of the card and makes it
> > available
> > to consumers of the ocxl driver via the ocxl_fn struct.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> > Acked-by: Frederic Barrat <fbarrat@...ux.ibm.com>
> > Acked-by: Andrew Donnellan <ajd@...ux.ibm.com>
> > ---
> >  drivers/misc/ocxl/config.c | 46
> > ++++++++++++++++++++++++++++++++++++++
> >  include/misc/ocxl.h        |  1 +
> >  2 files changed, 47 insertions(+)
> > 
> > diff --git a/drivers/misc/ocxl/config.c
> > b/drivers/misc/ocxl/config.c
> > index fb0c3b6f8312..a9203c309365 100644
> > --- a/drivers/misc/ocxl/config.c
> > +++ b/drivers/misc/ocxl/config.c
> > @@ -71,6 +71,51 @@ static int find_dvsec_afu_ctrl(struct pci_dev
> > *dev, u8 afu_idx)
> >  	return 0;
> >  }
> >  
> > +/**
> 
> Make sure anything you mark as kernel doc with /** is valid
> kernel-doc.
> 

Ok

> > + * Find a related PCI device (function 0)
> > + * @device: PCI device to match
> > + *
> > + * Returns a pointer to the related device, or null if not found
> > + */
> > +static struct pci_dev *get_function_0(struct pci_dev *dev)
> > +{
> > +	unsigned int devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 0); //
> > Look for function 0
> 
> Not sure the trailing comment adds much.
> 
> I'd personally not bother with this wrapper at all and just call
> the pci functions directly where needed.
> 

I'm not that familiar with the macros, so its not immediately obvious
to me what it's doing, so my preference is to leave it.
> > +
> > +	return pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
> > +					dev->bus->number, devfn);
> > +}
> > +
> > +static void read_serial(struct pci_dev *dev, struct ocxl_fn_config
> > *fn)
> > +{
> > +	u32 low, high;
> > +	int pos;
> > +
> > +	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DSN);
> > +	if (pos) {
> > +		pci_read_config_dword(dev, pos + 0x04, &low);
> > +		pci_read_config_dword(dev, pos + 0x08, &high);
> > +
> > +		fn->serial = low | ((u64)high) << 32;
> > +
> > +		return;
> > +	}
> > +
> > +	if (PCI_FUNC(dev->devfn) != 0) {
> > +		struct pci_dev *related = get_function_0(dev);
> > +
> > +		if (!related) {
> > +			fn->serial = 0;
> > +			return;
> > +		}
> > +
> > +		read_serial(related, fn);
> > +		pci_dev_put(related);
> > +		return;
> > +	}
> > +
> > +	fn->serial = 0;
> > +}
> > +
> >  static void read_pasid(struct pci_dev *dev, struct ocxl_fn_config
> > *fn)
> >  {
> >  	u16 val;
> > @@ -208,6 +253,7 @@ int ocxl_config_read_function(struct pci_dev
> > *dev, struct ocxl_fn_config *fn)
> >  	int rc;
> >  
> >  	read_pasid(dev, fn);
> > +	read_serial(dev, fn);
> >  
> >  	rc = read_dvsec_tl(dev, fn);
> >  	if (rc) {
> > diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> > index 6f7c02f0d5e3..9843051c3c5b 100644
> > --- a/include/misc/ocxl.h
> > +++ b/include/misc/ocxl.h
> > @@ -46,6 +46,7 @@ struct ocxl_fn_config {
> >  	int dvsec_afu_info_pos; /* offset of the AFU information DVSEC
> > */
> >  	s8 max_pasid_log;
> >  	s8 max_afu_index;
> > +	u64 serial;
> >  };
> >  
> >  enum ocxl_endian {
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819