linux-kernel - Re: [PATCH 1/4] of/pci: Provide support for parsing PCI DT ranges property

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Message-ID: <20130212064523.GA28850@avionic-0098.mockup.avionic-design.de>
Date:	Tue, 12 Feb 2013 07:45:23 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Rob Herring <robherring2@...il.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Andrew Murray <andrew.murray@....com>,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] of/pci: Provide support for parsing PCI DT ranges
 property

On Mon, Feb 11, 2013 at 01:43:03PM -0600, Rob Herring wrote:
> On 02/11/2013 02:22 AM, Thierry Reding wrote:
> > From: Andrew Murray <andrew.murray@....com>
> > 
> > DT bindings for PCI host bridges often use the ranges property to describe
> > memory and IO ranges - this binding tends to be the same across architectures
> > yet several parsing implementations exist, e.g. arch/mips/pci/pci.c,
> > arch/powerpc/kernel/pci-common.c, arch/sparc/kernel/pci.c and
> > arch/microblaze/pci/pci-common.c (clone of PPC). Some of these duplicate
> > functionality provided by drivers/of/address.c.
> > 
> > This patch provides a common iterator-based parser for the ranges property, it
> > is hoped this will reduce DT representation differences between architectures
> > and that architectures will migrate in part to this new parser.
> > 
> > It is also hoped (and the motativation for the patch) that this patch will
> > reduce duplication of code when writing host bridge drivers that are supported
> > by multiple architectures.
> > 
> > This patch provides struct resources from a device tree node, e.g.:
> > 
> > 	u32 *last = NULL;
> > 	struct resource res;
> > 	while ((last = of_pci_process_ranges(np, res, last))) {
> > 		//do something with res
> > 	}
> > 
> > Platforms with quirks can then do what they like with the resource or migrate
> > common quirk handling to the parser. In an ideal world drivers can just request
> > the obtained resources and pass them on (e.g. pci_add_resource_offset).
> > 
> > Signed-off-by: Andrew Murray <Andrew.Murray@....com>
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> > Signed-off-by: Thierry Reding <thierry.reding@...onic-design.de>
> > ---
> >  drivers/of/address.c       | 63 ++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/of_address.h |  9 +++++++
> >  2 files changed, 72 insertions(+)
> > 
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 04da786..f607008 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -13,6 +13,7 @@
> >  #define OF_CHECK_COUNTS(na, ns)	(OF_CHECK_ADDR_COUNT(na) && (ns) > 0)
> >  
> >  static struct of_bus *of_match_bus(struct device_node *np);
> > +static struct of_bus *of_find_bus(const char *name);
> 
> Can you move this function up to avoid the forward declaration.

It needs to be defined after the of_busses structure, which is defined
below the CONFIG_PCI block where of_pci_process_ranges() is defined. I'd
have to move that one as well and add another #ifdef CONFIG_PCI section.
If you prefer that I can do that.

> > +static struct of_bus *of_find_bus(const char *name)
> > +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(of_busses); i++)
> > +		if (strcmp(name, of_busses[i].name) == 0)
>                                               ^
> space needed.

I don't understand. Do you want the space to go between '.' and "name"?

Thierry

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