Patchwork pci: Provide support for parsing PCI DT ranges property

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Submitter Andrew Murray
Date Dec. 12, 2012, 4:37 p.m.
Message ID <20121212163749.GA17371@arm.com>
Download mbox | patch
Permalink /patch/205577/
State Not Applicable
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Comments

Andrew Murray - Dec. 12, 2012, 4:37 p.m.
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@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/of/address.c       |   53 +++++++++++++++++++++++++++++++++++++++++++-
 include/linux/of_address.h |    7 +++++
 2 files changed, 59 insertions(+), 1 deletions(-)
Thierry Reding - Dec. 13, 2012, 9:13 a.m.
On Wed, Dec 12, 2012 at 04:37:50PM +0000, Andrew Murray wrote:
> 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@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> ---
>  drivers/of/address.c       |   53 +++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/of_address.h |    7 +++++
>  2 files changed, 59 insertions(+), 1 deletions(-)

Hi Andrew,

I don't like iterator interfaces too much, but I can live with that.
Other than that the patch looks good to me and I'll try to work it into
my Tegra PCIe patch series.

Just two minor comments below.

> diff --git a/drivers/of/address.c b/drivers/of/address.c
[...]
> @@ -421,7 +472,7 @@ u64 __of_translate_address(struct device_node *dev, const __be32 *in_addr,
>  		goto bail;
>  	bus = of_match_bus(parent);
>  
> -	/* Cound address cells & copy address locally */
> +	/* Count address cells & copy address locally */
>  	bus->count_cells(dev, &na, &ns);
>  	if (!OF_CHECK_COUNTS(na, ns)) {
>  		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",

This is really minor, but it should still go into a separate patch.

> diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> index 01b925a..4582b20 100644
> --- a/include/linux/of_address.h
> +++ b/include/linux/of_address.h
> @@ -26,6 +26,8 @@ static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
>  #define pci_address_to_pio pci_address_to_pio
>  #endif
>  
> +const __be32 *of_pci_process_ranges(struct device_node *node,
> +				    struct resource *res, const __be32 *from);
>  #else /* CONFIG_OF_ADDRESS */
>  static inline int of_address_to_resource(struct device_node *dev, int index,
>  					 struct resource *r)
> @@ -48,6 +50,11 @@ static inline const u32 *of_get_address(struct device_node *dev, int index,
>  {
>  	return NULL;
>  }
> +const __be32 *of_pci_process_ranges(struct device_node *node,

There should be a blank line to separate the above two lines.

Thierry
Andrew Murray - Dec. 13, 2012, 9:45 a.m.
On Thu, Dec 13, 2012 at 09:13:33AM +0000, Thierry Reding wrote:
> Hi Andrew,
> 
> I don't like iterator interfaces too much, but I can live with that.
> Other than that the patch looks good to me and I'll try to work it into
> my Tegra PCIe patch series.
> 
> Just two minor comments below.
> 
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> [...]
> > @@ -421,7 +472,7 @@ u64 __of_translate_address(struct device_node *dev, const __be32 *in_addr,
> >  		goto bail;
> >  	bus = of_match_bus(parent);
> >  
> > -	/* Cound address cells & copy address locally */
> > +	/* Count address cells & copy address locally */
> >  	bus->count_cells(dev, &na, &ns);
> >  	if (!OF_CHECK_COUNTS(na, ns)) {
> >  		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
> 
> This is really minor, but it should still go into a separate patch.
> 
> > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> > index 01b925a..4582b20 100644
> > --- a/include/linux/of_address.h
> > +++ b/include/linux/of_address.h
> > @@ -26,6 +26,8 @@ static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
> >  #define pci_address_to_pio pci_address_to_pio
> >  #endif
> >  
> > +const __be32 *of_pci_process_ranges(struct device_node *node,
> > +				    struct resource *res, const __be32 *from);
> >  #else /* CONFIG_OF_ADDRESS */
> >  static inline int of_address_to_resource(struct device_node *dev, int index,
> >  					 struct resource *r)
> > @@ -48,6 +50,11 @@ static inline const u32 *of_get_address(struct device_node *dev, int index,
> >  {
> >  	return NULL;
> >  }
> > +const __be32 *of_pci_process_ranges(struct device_node *node,
> 
> There should be a blank line to separate the above two lines.
> 

Thanks for the feedback.

I will send another patch for the typo and leave this patch with you for
working into your existing series.

Andrew Murray

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Thierry Reding - Dec. 13, 2012, 10:03 a.m.
On Thu, Dec 13, 2012 at 09:45:43AM +0000, Andrew Murray wrote:
> On Thu, Dec 13, 2012 at 09:13:33AM +0000, Thierry Reding wrote:
> > Hi Andrew,
> > 
> > I don't like iterator interfaces too much, but I can live with that.
> > Other than that the patch looks good to me and I'll try to work it into
> > my Tegra PCIe patch series.
> > 
> > Just two minor comments below.
> > 
> > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > [...]
> > > @@ -421,7 +472,7 @@ u64 __of_translate_address(struct device_node *dev, const __be32 *in_addr,
> > >  		goto bail;
> > >  	bus = of_match_bus(parent);
> > >  
> > > -	/* Cound address cells & copy address locally */
> > > +	/* Count address cells & copy address locally */
> > >  	bus->count_cells(dev, &na, &ns);
> > >  	if (!OF_CHECK_COUNTS(na, ns)) {
> > >  		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
> > 
> > This is really minor, but it should still go into a separate patch.
> > 
> > > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> > > index 01b925a..4582b20 100644
> > > --- a/include/linux/of_address.h
> > > +++ b/include/linux/of_address.h
> > > @@ -26,6 +26,8 @@ static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
> > >  #define pci_address_to_pio pci_address_to_pio
> > >  #endif
> > >  
> > > +const __be32 *of_pci_process_ranges(struct device_node *node,
> > > +				    struct resource *res, const __be32 *from);
> > >  #else /* CONFIG_OF_ADDRESS */
> > >  static inline int of_address_to_resource(struct device_node *dev, int index,
> > >  					 struct resource *r)
> > > @@ -48,6 +50,11 @@ static inline const u32 *of_get_address(struct device_node *dev, int index,
> > >  {
> > >  	return NULL;
> > >  }
> > > +const __be32 *of_pci_process_ranges(struct device_node *node,
> > 
> > There should be a blank line to separate the above two lines.
> > 
> 
> Thanks for the feedback.
> 
> I will send another patch for the typo and leave this patch with you for
> working into your existing series.

I suppose you have your own series that uses this patch?

Thierry
Andrew Murray - Dec. 13, 2012, 10:34 a.m.
On Thu, Dec 13, 2012 at 10:03:18AM +0000, Thierry Reding wrote:
> On Thu, Dec 13, 2012 at 09:45:43AM +0000, Andrew Murray wrote:
> > On Thu, Dec 13, 2012 at 09:13:33AM +0000, Thierry Reding wrote:
> > > Hi Andrew,
> > > 
> > > I don't like iterator interfaces too much, but I can live with that.
> > > Other than that the patch looks good to me and I'll try to work it into
> > > my Tegra PCIe patch series.
> > > 
> > > Just two minor comments below.
> > > 
> > > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > [...]
> > > > @@ -421,7 +472,7 @@ u64 __of_translate_address(struct device_node *dev, const __be32 *in_addr,
> > > >  		goto bail;
> > > >  	bus = of_match_bus(parent);
> > > >  
> > > > -	/* Cound address cells & copy address locally */
> > > > +	/* Count address cells & copy address locally */
> > > >  	bus->count_cells(dev, &na, &ns);
> > > >  	if (!OF_CHECK_COUNTS(na, ns)) {
> > > >  		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
> > > 
> > > This is really minor, but it should still go into a separate patch.
> > > 
> > > > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> > > > index 01b925a..4582b20 100644
> > > > --- a/include/linux/of_address.h
> > > > +++ b/include/linux/of_address.h
> > > > @@ -26,6 +26,8 @@ static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
> > > >  #define pci_address_to_pio pci_address_to_pio
> > > >  #endif
> > > >  
> > > > +const __be32 *of_pci_process_ranges(struct device_node *node,
> > > > +				    struct resource *res, const __be32 *from);
> > > >  #else /* CONFIG_OF_ADDRESS */
> > > >  static inline int of_address_to_resource(struct device_node *dev, int index,
> > > >  					 struct resource *r)
> > > > @@ -48,6 +50,11 @@ static inline const u32 *of_get_address(struct device_node *dev, int index,
> > > >  {
> > > >  	return NULL;
> > > >  }
> > > > +const __be32 *of_pci_process_ranges(struct device_node *node,
> > > 
> > > There should be a blank line to separate the above two lines.
> > > 
> > 
> > Thanks for the feedback.
> > 
> > I will send another patch for the typo and leave this patch with you for
> > working into your existing series.
> 
> I suppose you have your own series that uses this patch?

Not yet, it may be some time before I submit my PCI host bridge driver. Though
I am making changes else where (e.g. this patch) which I'm hoping to submit as
early as possible. I can rebase my work for these upstream dependencies.

I can re-spin this patch with your suggested changes if you prefer?

Andrew Murray


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Grant Likely - Dec. 15, 2012, 1:06 a.m.
On Wed, Dec 12, 2012 at 4:37 PM, Andrew Murray <Andrew.Murray@arm.com> wrote:
> 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.

Hi Andrew,

Thanks for looking into this. This definitely needs to be done.

However, I cannot merge this patch as-is because it actually makes
things worse by adding yet another implementation of the parsing code.
Plus it doesn't actually have any users.  :-)

Instead, move the existing code that you need out of
arch/powerpc/kernel/pci-common.c into a shared place and add in the
features you need. Bonus points if you fixup microblaze or others at
the same time.

g.
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Thierry Reding - Dec. 20, 2012, 8:25 a.m.
On Wed, Dec 12, 2012 at 04:37:50PM +0000, Andrew Murray wrote:
[...]
> diff --git a/drivers/of/address.c b/drivers/of/address.c
[...]
> +	start = of_get_property(node, "ranges", &rlen);
> +	if (start == NULL)
> +		return NULL;
> +
> +	end = start + rlen;

I'm currently rewriting large parts of the Tegra PCIe controller driver
and I'm trying to use this new API. This seems to work fine, except that
I think this line needs to be:

	end = start + rlen / sizeof(__be32);

Otherwise we'll try to process 4 times as many ranges as there are.

Thierry
Andrew Murray - Jan. 14, 2013, 9:15 a.m.
On Thu, Dec 20, 2012 at 08:25:00AM +0000, Thierry Reding wrote:
> On Wed, Dec 12, 2012 at 04:37:50PM +0000, Andrew Murray wrote:
> [...]
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> [...]
> > +	start = of_get_property(node, "ranges", &rlen);
> > +	if (start == NULL)
> > +		return NULL;
> > +
> > +	end = start + rlen;
> 
> I'm currently rewriting large parts of the Tegra PCIe controller driver
> and I'm trying to use this new API. This seems to work fine, except that
> I think this line needs to be:
> 
> 	end = start + rlen / sizeof(__be32);
> 
> Otherwise we'll try to process 4 times as many ranges as there are.
> 
> Thierry

Good catch. Thanks for taking this on.

Andrew Murray


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Andrew Murray - Jan. 14, 2013, 9:24 a.m.
On Sat, Dec 15, 2012 at 01:06:41AM +0000, Grant Likely wrote:
> On Wed, Dec 12, 2012 at 4:37 PM, Andrew Murray <Andrew.Murray@arm.com> wrote:
> > 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.
> 
> Hi Andrew,
> 
> Thanks for looking into this. This definitely needs to be done.
> 
> However, I cannot merge this patch as-is because it actually makes
> things worse by adding yet another implementation of the parsing code.
> Plus it doesn't actually have any users.  :-)

I understand. Though I see Thierry has included this in his patch set - I
guess that means there is potentially one user now :).

> 
> Instead, move the existing code that you need out of
> arch/powerpc/kernel/pci-common.c into a shared place and add in the
> features you need. Bonus points if you fixup microblaze or others at
> the same time.

In most part the patch I submitted was the common code from powerpc but
without quirks and tie-ins to powerpc structures. I'd like to convert
powerpc to using my patch and others but won't get time to do this at
present :(

> 
> g.
> 
Andrew Murray

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Patch

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 7e262a6..03bfe61 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -219,6 +219,57 @@  int of_pci_address_to_resource(struct device_node *dev, int bar,
 	return __of_address_to_resource(dev, addrp, size, flags, NULL, r);
 }
 EXPORT_SYMBOL_GPL(of_pci_address_to_resource);
+
+const __be32 *of_pci_process_ranges(struct device_node *node,
+				    struct resource *res, const __be32 *from)
+{
+	const __be32 *start, *end;
+	int na, ns, np, pna;
+	int rlen;
+	struct of_bus *bus;
+	WARN_ON(!res);
+
+	bus = of_match_bus(node);
+	bus->count_cells(node, &na, &ns);
+	if (!OF_CHECK_COUNTS(na, ns)) {
+		pr_err("Bad cell count for %s\n", node->full_name);
+		return NULL;
+	}
+
+	pna = of_n_addr_cells(node);
+	np = pna + na + ns;
+
+	start = of_get_property(node, "ranges", &rlen);
+	if (start == NULL)
+		return NULL;
+
+	end = start + rlen;
+
+	if (!from)
+		from = start;
+
+	while (from + np <= end) {
+		u64 cpu_addr, size;
+
+		cpu_addr = of_translate_address(node, from + na);
+		size = of_read_number(from + na + pna, ns);
+		res->flags = bus->get_flags(from);
+		from += np;
+
+		if (cpu_addr == OF_BAD_ADDR || size == 0)
+			continue;
+
+		res->name = node->full_name;
+		res->start = cpu_addr;
+		res->end = res->start + size - 1;
+		res->parent = res->child = res->sibling = NULL;
+		return from;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(of_pci_process_ranges);
+
 #endif /* CONFIG_PCI */
 
 /*
@@ -421,7 +472,7 @@  u64 __of_translate_address(struct device_node *dev, const __be32 *in_addr,
 		goto bail;
 	bus = of_match_bus(parent);
 
-	/* Cound address cells & copy address locally */
+	/* Count address cells & copy address locally */
 	bus->count_cells(dev, &na, &ns);
 	if (!OF_CHECK_COUNTS(na, ns)) {
 		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 01b925a..4582b20 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -26,6 +26,8 @@  static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
 #define pci_address_to_pio pci_address_to_pio
 #endif
 
+const __be32 *of_pci_process_ranges(struct device_node *node,
+				    struct resource *res, const __be32 *from);
 #else /* CONFIG_OF_ADDRESS */
 static inline int of_address_to_resource(struct device_node *dev, int index,
 					 struct resource *r)
@@ -48,6 +50,11 @@  static inline const u32 *of_get_address(struct device_node *dev, int index,
 {
 	return NULL;
 }
+const __be32 *of_pci_process_ranges(struct device_node *node,
+				    struct resource *res, const __be32 *from)
+{
+	return NULL;
+}
 #endif /* CONFIG_OF_ADDRESS */