From mboxrd@z Thu Jan  1 00:00:00 1970
From: Liviu Dudau <Liviu.Dudau@arm.com>
Subject: Re: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper
 function.
Date: Wed, 2 Jul 2014 17:00:34 +0100
Message-ID: <20140702160034.GP2173@e106497-lin.cambridge.arm.com>
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To: Will Deacon <will.deacon@arm.com>
Cc: linux-pci <linux-pci@vger.kernel.org>, Bjorn Helgaas <bhelgaas@google.com>, Catalin Marinas <Catalin.Marinas@arm.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Arnd Bergmann <arnd@arndb.de>, linaro-kernel <linaro-kernel@lists.linaro.org>, Tanmay Inamdar <tinamdar@apm.com>, Grant Likely <grant.likely@secretlab.ca>, Sinan Kaya <okaya@codeaurora.org>, Jingoo Han <jg1.han@samsung.com>, Kukjin Kim <kgene.kim@samsung.com>, Suravee Suthikulanit <suravee.suthikulpanit@amd.com>, LKML <linux-kernel@vger.kernel.org>, Device Tree ML <devicetree@vger.kernel.org>, LAKML <linux-arm-kernel@lists.infradead.org>
List-Id: devicetree@vger.kernel.org

On Wed, Jul 02, 2014 at 12:22:22PM +0100, Will Deacon wrote:
> On Tue, Jul 01, 2014 at 07:43:28PM +0100, Liviu Dudau wrote:
> > Some architectures do not have a simple view of the PCI I/O space
> > and instead use a range of CPU addresses that map to bus addresses.=
 For
> > some architectures these ranges will be expressed by OF bindings
> > in a device tree file.
> >=20
> > Introduce a pci_register_io_range() helper function with a generic
> > implementation that can be used by such architectures to keep track
> > of the I/O ranges described by the PCI bindings. If the PCI_IOBASE
> > macro is not defined that signals lack of support for PCI and we
> > return an error.
>=20
> [...]
>=20
> > +/*
> > + * Record the PCI IO range (expressed as CPU physical address + si=
ze).
> > + * Return a negative value if an error has occured, zero otherwise
> > + */
> > +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t=
 size)
> > +{
> > +#ifdef PCI_IOBASE
> > +	struct io_range *res;
> > +	resource_size_t allocated_size =3D 0;
> > +
> > +	/* check if the range hasn't been previously recorded */
> > +	list_for_each_entry(res, &io_range_list, list) {
> > +		if (addr >=3D res->start && addr + size <=3D res->start + size)
> > +			return 0;
> > +		allocated_size +=3D res->size;
> > +	}
> > +
> > +	/* range not registed yet, check for available space */
> > +	if (allocated_size + size - 1 > IO_SPACE_LIMIT)
> > +		return -E2BIG;
> > +
> > +	/* add the range to the list */
> > +	res =3D kzalloc(sizeof(*res), GFP_KERNEL);
> > +	if (!res)
> > +		return -ENOMEM;
> > +
> > +	res->start =3D addr;
> > +	res->size =3D size;
> > +
> > +	list_add_tail(&res->list, &io_range_list);
> > +
> > +	return 0;
>=20
> Hopefully a stupid question, but how is this serialised? I'm just sur=
prised
> that adding to and searching a list are sufficient, unless there's a =
big
> lock somewhere.

Sorry, tripped into my own filters!

You are right, there is no serialisation here, will add one.

Best regards,
Liviu

>=20
> Will
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>=20

--=20
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    =C2=AF\_(=E3=83=84)_/=C2=AF