linux-kernel - Re: [PATCH v8 9/9] pci: Remap I/O bus resources into CPU space with pci_remap

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Date:	Mon, 14 Jul 2014 20:15:48 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	Liviu Dudau <Liviu.Dudau@....com>,
	linux-pci <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Will Deacon <Will.Deacon@....com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Sinan Kaya <okaya@...eaurora.org>,
	Jingoo Han <jg1.han@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Suravee Suthikulanit <suravee.suthikulpanit@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Device Tree ML <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 9/9] pci: Remap I/O bus resources into CPU space with pci_remap_iospace()

On Monday 14 July 2014 17:54:43 Catalin Marinas wrote:
> On Tue, Jul 01, 2014 at 07:43:34PM +0100, Liviu Dudau wrote:
> > Introduce a default implementation for remapping PCI bus I/O resources
> > onto the CPU address space. Architectures with special needs may
> > provide their own version, but most should be able to use this one.
> [...]
> > +/**
> > + *   pci_remap_iospace - Remap the memory mapped I/O space
> > + *   @res: Resource describing the I/O space
> > + *   @phys_addr: physical address where the range will be mapped.
> > + *
> > + *   Remap the memory mapped I/O space described by the @res
> > + *   into the CPU physical address space. Only architectures
> > + *   that have memory mapped IO defined (and hence PCI_IOBASE)
> > + *   should call this function.
> > + */
> > +int __weak pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr)
> > +{
> > +     int err = -ENODEV;
> > +
> > +#ifdef PCI_IOBASE
> > +     if (!(res->flags & IORESOURCE_IO))
> > +             return -EINVAL;
> > +
> > +     if (res->end > IO_SPACE_LIMIT)
> > +             return -EINVAL;
> > +
> > +     err = ioremap_page_range(res->start + (unsigned long)PCI_IOBASE,
> > +                             res->end + 1 + (unsigned long)PCI_IOBASE,
> > +                             phys_addr, __pgprot(PROT_DEVICE_nGnRE));
> 
> Except that PROT_DEVICE_nGnRE is arm64 only. I think that's a function
> that should remain arch specific.
> 

How about #defining a macro with the correct pgprot value in asm/pci.h
or asm/pgtable.h?
We can provide a default for that in another architecture independent
location.

	Arnd
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