diff mbox

[v11,08/10] OF: PCI: Add support for parsing PCI host bridge resources from DT

Message ID 1411003825-21521-9-git-send-email-Liviu.Dudau@arm.com
State New
Headers show

Commit Message

Liviu Dudau Sept. 18, 2014, 1:30 a.m. UTC
Provide a function to parse the PCI DT ranges that can be used to
create a pci_host_bridge structure together with its associated
bus.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/of/of_pci.c    | 108 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_pci.h |  11 +++++
 2 files changed, 119 insertions(+)

Comments

Bjorn Helgaas Sept. 19, 2014, 9:06 p.m. UTC | #1
On Thu, Sep 18, 2014 at 02:30:23AM +0100, Liviu Dudau wrote:
> Provide a function to parse the PCI DT ranges that can be used to
> create a pci_host_bridge structure together with its associated
> bus.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Grant Likely <grant.likely@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> ---
>  drivers/of/of_pci.c    | 108 +++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_pci.h |  11 +++++
>  2 files changed, 119 insertions(+)
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 7eaeac2..c18b8da 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -1,7 +1,9 @@
>  #include <linux/kernel.h>
>  #include <linux/export.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/of_pci.h>
> +#include <linux/slab.h>
>  
>  #include "of_private.h"
>  
> @@ -151,6 +153,112 @@ int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
>  }
>  EXPORT_SYMBOL_GPL(of_pci_get_domain_nr);
>  
> +/**
> + * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
> + * @dev: device node of the host bridge having the range property
> + * @busno: bus number associated with the bridge root bus
> + * @bus_max: maximum number of busses for this bridge
> + * @resources: list where the range of resources will be added after DT parsing
> + * @io_base: pointer to a variable that will contain on return the physical
> + * address for the start of the I/O range.
> + *
> + * It is the callers job to free the @resources list.
> + *
> + * This function will parse the "ranges" property of a PCI host bridge device
> + * node and setup the resource mapping based on its content. It is expected
> + * that the property conforms with the Power ePAPR document.
> + *
> + * It returns zero if the range parsing has been successful or a standard error
> + * value if it failed.
> + */
> +int of_pci_get_host_bridge_resources(struct device_node *dev,
> +			unsigned char busno, unsigned char bus_max,
> +			struct list_head *resources, resource_size_t *io_base)
> +{
> +	struct resource *res;
> +	struct resource *bus_range;
> +	struct of_pci_range range;
> +	struct of_pci_range_parser parser;
> +	char range_type[4];
> +	int err;
> +
> +	if (!io_base)
> +		return -EINVAL;
> +	*io_base = OF_BAD_ADDR;
> +
> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> +	if (!bus_range)
> +		return -ENOMEM;
> +
> +	pr_info("PCI host bridge %s ranges:\n", dev->full_name);
> +
> +	err = of_pci_parse_bus_range(dev, bus_range);
> +	if (err) {
> +		bus_range->start = busno;
> +		bus_range->end = bus_max;
> +		bus_range->flags = IORESOURCE_BUS;
> +		pr_info("  No bus range found for %s, using %pR\n",
> +			dev->full_name, &bus_range);
> +	} else {
> +		if (bus_range->end > bus_range->start + bus_max)
> +			bus_range->end = bus_range->start + bus_max;
> +	}
> +	pci_add_resource(resources, bus_range);
> +
> +	/* Check for ranges property */
> +	err = of_pci_range_parser_init(&parser, dev);
> +	if (err)
> +		goto parse_failed;
> +
> +	pr_debug("Parsing ranges property...\n");
> +	for_each_of_pci_range(&parser, &range) {
> +		/* Read next ranges element */
> +		if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
> +			snprintf(range_type, 4, " IO");
> +		else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
> +			snprintf(range_type, 4, "MEM");
> +		else
> +			snprintf(range_type, 4, "err");
> +		pr_info("  %s %#010llx..%#010llx -> %#010llx\n", range_type,
> +			range.cpu_addr, range.cpu_addr + range.size - 1,
> +			range.pci_addr);
> +
> +		/*
> +		 * If we failed translation or got a zero-sized region
> +		 * then skip this range
> +		 */
> +		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> +			continue;
> +
> +		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> +		if (!res) {
> +			err = -ENOMEM;
> +			goto parse_failed;
> +		}
> +
> +		err = of_pci_range_to_resource(&range, dev, res);
> +		if (err) {
> +			kfree(res);
> +			goto parse_failed;
> +		}
> +
> +		if (resource_type(res) == IORESOURCE_IO) {
> +			if (*io_base != OF_BAD_ADDR)
> +				pr_warn("More than one I/O resource converted. CPU offset for old range lost!\n");

It'd be nice if the output included a hint about which device this warning
applies to.

> +			*io_base = range.cpu_addr;
> +		}
> +
> +		pci_add_resource_offset(resources, res,	res->start - range.pci_addr);
> +	}
> +
> +	return 0;
> +
> +parse_failed:
> +	pci_free_resource_list(resources);
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
> +
>  #ifdef CONFIG_PCI_MSI
>  
>  static LIST_HEAD(of_pci_msi_chip_list);
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 3a3824c..a4b8a85 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -16,6 +16,10 @@ int of_pci_get_devfn(struct device_node *np);
>  int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
>  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
>  int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing);
> +int of_pci_get_host_bridge_resources(struct device_node *dev,
> +			unsigned char busno, unsigned char bus_max,
> +			struct list_head *resources, resource_size_t *io_base);
> +
>  #else
>  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
>  {
> @@ -50,6 +54,13 @@ of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
>  {
>  	return -1;
>  }
> +
> +int of_pci_get_host_bridge_resources(struct device_node *dev,
> +			unsigned char busno, unsigned char bus_max,
> +			struct list_head *resources, resource_size_t *io_base);
> +{
> +	return -EINVAL;
> +}
>  #endif
>  
>  #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
> -- 
> 2.1.0
> 
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Rob Herring Sept. 20, 2014, 12:28 a.m. UTC | #2
On 09/19/2014 04:06 PM, Bjorn Helgaas wrote:
> On Thu, Sep 18, 2014 at 02:30:23AM +0100, Liviu Dudau wrote:
>> Provide a function to parse the PCI DT ranges that can be used to
>> create a pci_host_bridge structure together with its associated
>> bus.
>>
>> Cc: Bjorn Helgaas <bhelgaas@google.com>
>> Cc: Arnd Bergmann <arnd@arndb.de>
>> Cc: Grant Likely <grant.likely@linaro.org>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
>> ---

[...]

>> +int of_pci_get_host_bridge_resources(struct device_node *dev,
>> +			unsigned char busno, unsigned char bus_max,
>> +			struct list_head *resources, resource_size_t *io_base)
>> +{
>> +	struct resource *res;
>> +	struct resource *bus_range;
>> +	struct of_pci_range range;
>> +	struct of_pci_range_parser parser;
>> +	char range_type[4];
>> +	int err;
>> +
>> +	if (!io_base)
>> +		return -EINVAL;
>> +	*io_base = OF_BAD_ADDR;
>> +
>> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);

This function does a lot of kalloc's but there is not an easy way to
undo those allocations. Hot unplug of a host bridge or probe error
handling would leak memory.

You could pass in struct device and use the devm_ variant (also
addressing Bjorn's comment), but not having an uninit/remove function
make what clean-up drivers have to do error prone. For example, on
uninit a driver needs to call pci_free_resource_list.

Rob
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Liviu Dudau Sept. 22, 2014, 11:43 a.m. UTC | #3
On Mon, Sep 22, 2014 at 10:32:28AM +0100, Robert Richter wrote:
> On 18.09.14 02:30:23, Liviu Dudau wrote:
> > +int of_pci_get_host_bridge_resources(struct device_node *dev,
> > +			unsigned char busno, unsigned char bus_max,
> > +			struct list_head *resources, resource_size_t *io_base)
> > +{
> > +	struct resource *res;
> > +	struct resource *bus_range;
> > +	struct of_pci_range range;
> > +	struct of_pci_range_parser parser;
> > +	char range_type[4];
> > +	int err;
> > +
> > +	if (!io_base)
> > +		return -EINVAL;
> > +	*io_base = OF_BAD_ADDR;
> 

Hi Robert,

> This breaks for mem-mapped pci host controllers. The patch below fixes
> this.

I think you mean PCI host controller that have only memory mapped ranges,
am I right? Initially I've read your reply as to mean that the host
controller is accessed through some memory mapped area, which I believe is
the case for all host controllers.

> 
> This series was tested with the fix on top for Cavium Thunder.
> 
> Tested-by: Robert Richter <rrichter@cavium.com>

Thanks for that!

> 
> -Robert
> 
> 
> 
> From e798af4fc2f664d1aff7e863489b8298f90e716e Mon Sep 17 00:00:00 2001
> From: Robert Richter <rrichter@cavium.com>
> Date: Mon, 22 Sep 2014 10:46:01 +0200
> Subject: [PATCH] OF: PCI: Fix creation of mem-mapped pci host bridges
> 
> The pci host bridge was not created if io_base was not set when
> calling of_pci_get_host_bridge_resources(). This is esp. the case for
> mem-mapped io (IORESOURCE_MEM). This patch fixes this. Function
> parameter io_base is optional now.

I think the message is misleading. What you want to do is make io_base
optional for the case where the PCI host bridge only expects to have only
IORESOURCE_MEM ranges and doesn't care about IORESOURCE_IO ones.

As I'm going to touch this area again to address a comment from Bjorn,
do you mind if I roll this patch into mine with your Signed-off-by and
the mention that you have made io_base optional?

Best regards,
Liviu

> 
> Signed-off-by: Robert Richter <rrichter@cavium.com>
> ---
>  drivers/of/of_pci.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index ffdb45ed8682..1f0e7c2505ee 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -182,9 +182,8 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>  	char range_type[4];
>  	int err;
>  
> -	if (!io_base)
> -		return -EINVAL;
> -	*io_base = OF_BAD_ADDR;
> +	if (io_base)
> +		*io_base = OF_BAD_ADDR;
>  
>  	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
>  	if (!bus_range)
> @@ -242,7 +241,7 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>  			goto parse_failed;
>  		}
>  
> -		if (resource_type(res) == IORESOURCE_IO) {
> +		if (io_base && resource_type(res) == IORESOURCE_IO) {
>  			if (*io_base != OF_BAD_ADDR)
>  				pr_warn("More than one I/O resource converted. CPU offset for old range lost!\n");
>  			*io_base = range.cpu_addr;
> -- 
> 2.1.0
> 
> --
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>
Robert Richter Sept. 22, 2014, 12:15 p.m. UTC | #4
On 22.09.14 12:43:17, Liviu Dudau wrote:
> On Mon, Sep 22, 2014 at 10:32:28AM +0100, Robert Richter wrote:
> > On 18.09.14 02:30:23, Liviu Dudau wrote:
> > > +int of_pci_get_host_bridge_resources(struct device_node *dev,
> > > +			unsigned char busno, unsigned char bus_max,
> > > +			struct list_head *resources, resource_size_t *io_base)
> > > +{
> > > +	struct resource *res;
> > > +	struct resource *bus_range;
> > > +	struct of_pci_range range;
> > > +	struct of_pci_range_parser parser;
> > > +	char range_type[4];
> > > +	int err;
> > > +
> > > +	if (!io_base)
> > > +		return -EINVAL;
> > > +	*io_base = OF_BAD_ADDR;
> > 
> 
> Hi Robert,
> 
> > This breaks for mem-mapped pci host controllers. The patch below fixes
> > this.
> 
> I think you mean PCI host controller that have only memory mapped ranges,
> am I right? Initially I've read your reply as to mean that the host
> controller is accessed through some memory mapped area, which I believe is
> the case for all host controllers.

Right, that's meant here. Sorry for the misleading comment.

> 
> > 
> > This series was tested with the fix on top for Cavium Thunder.
> > 
> > Tested-by: Robert Richter <rrichter@cavium.com>
> 
> Thanks for that!
> 
> > 
> > -Robert
> > 
> > 
> > 
> > From e798af4fc2f664d1aff7e863489b8298f90e716e Mon Sep 17 00:00:00 2001
> > From: Robert Richter <rrichter@cavium.com>
> > Date: Mon, 22 Sep 2014 10:46:01 +0200
> > Subject: [PATCH] OF: PCI: Fix creation of mem-mapped pci host bridges
> > 
> > The pci host bridge was not created if io_base was not set when
> > calling of_pci_get_host_bridge_resources(). This is esp. the case for
> > mem-mapped io (IORESOURCE_MEM). This patch fixes this. Function
> > parameter io_base is optional now.
> 
> I think the message is misleading. What you want to do is make io_base
> optional for the case where the PCI host bridge only expects to have only
> IORESOURCE_MEM ranges and doesn't care about IORESOURCE_IO ones.
> 
> As I'm going to touch this area again to address a comment from Bjorn,
> do you mind if I roll this patch into mine with your Signed-off-by and
> the mention that you have made io_base optional?

Sure, fine with me.

Thanks,

-Robert


> 
> Best regards,
> Liviu
> 
> > 
> > Signed-off-by: Robert Richter <rrichter@cavium.com>
> > ---
> >  drivers/of/of_pci.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > index ffdb45ed8682..1f0e7c2505ee 100644
> > --- a/drivers/of/of_pci.c
> > +++ b/drivers/of/of_pci.c
> > @@ -182,9 +182,8 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> >  	char range_type[4];
> >  	int err;
> >  
> > -	if (!io_base)
> > -		return -EINVAL;
> > -	*io_base = OF_BAD_ADDR;
> > +	if (io_base)
> > +		*io_base = OF_BAD_ADDR;
> >  
> >  	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> >  	if (!bus_range)
> > @@ -242,7 +241,7 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
> >  			goto parse_failed;
> >  		}
> >  
> > -		if (resource_type(res) == IORESOURCE_IO) {
> > +		if (io_base && resource_type(res) == IORESOURCE_IO) {
> >  			if (*io_base != OF_BAD_ADDR)
> >  				pr_warn("More than one I/O resource converted. CPU offset for old range lost!\n");
> >  			*io_base = range.cpu_addr;
> > -- 
> > 2.1.0
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 
> -- 
> ====================
> | I would like to |
> | fix the world,  |
> | but they're not |
> | giving me the   |
>  \ source code!  /
>   ---------------
>     ¯\_(ツ)_/¯
> 
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Liviu Dudau Sept. 22, 2014, 5:55 p.m. UTC | #5
On Sat, Sep 20, 2014 at 01:28:38AM +0100, Rob Herring wrote:
> On 09/19/2014 04:06 PM, Bjorn Helgaas wrote:
> > On Thu, Sep 18, 2014 at 02:30:23AM +0100, Liviu Dudau wrote:
> >> Provide a function to parse the PCI DT ranges that can be used to
> >> create a pci_host_bridge structure together with its associated
> >> bus.
> >>
> >> Cc: Bjorn Helgaas <bhelgaas@google.com>
> >> Cc: Arnd Bergmann <arnd@arndb.de>
> >> Cc: Grant Likely <grant.likely@linaro.org>
> >> Cc: Rob Herring <robh+dt@kernel.org>
> >> Cc: Catalin Marinas <catalin.marinas@arm.com>
> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> >> ---
> 
> [...]
> 
> >> +int of_pci_get_host_bridge_resources(struct device_node *dev,
> >> +			unsigned char busno, unsigned char bus_max,
> >> +			struct list_head *resources, resource_size_t *io_base)
> >> +{
> >> +	struct resource *res;
> >> +	struct resource *bus_range;
> >> +	struct of_pci_range range;
> >> +	struct of_pci_range_parser parser;
> >> +	char range_type[4];
> >> +	int err;
> >> +
> >> +	if (!io_base)
> >> +		return -EINVAL;
> >> +	*io_base = OF_BAD_ADDR;
> >> +
> >> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> 
> This function does a lot of kalloc's but there is not an easy way to
> undo those allocations. Hot unplug of a host bridge or probe error
> handling would leak memory.
> 
> You could pass in struct device and use the devm_ variant (also
> addressing Bjorn's comment), but not having an uninit/remove function
> make what clean-up drivers have to do error prone. For example, on
> uninit a driver needs to call pci_free_resource_list.

If the function fails to parse the ranges for whatever reason it will
call pci_free_resource_list on the resources that have been added already
and it will clean up. If it is successful, then it is the job of the caller
to free the list, as mentioned in the comment associated with the function.

The reason why I am reluctant to use devm_ here is that the ranges are only
parsed here, no filtering is applied. Architectures and/or host bridge
drivers can/could impose additional restrictions to the list before passing
it to pci_scan_root_bus() for example.

Best regards,
Liviu

> 
> Rob
>
Rob Herring Sept. 22, 2014, 10:11 p.m. UTC | #6
On Mon, Sep 22, 2014 at 12:55 PM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> On Sat, Sep 20, 2014 at 01:28:38AM +0100, Rob Herring wrote:
>> On 09/19/2014 04:06 PM, Bjorn Helgaas wrote:
>> > On Thu, Sep 18, 2014 at 02:30:23AM +0100, Liviu Dudau wrote:
>> >> Provide a function to parse the PCI DT ranges that can be used to
>> >> create a pci_host_bridge structure together with its associated
>> >> bus.
>> >>
>> >> Cc: Bjorn Helgaas <bhelgaas@google.com>
>> >> Cc: Arnd Bergmann <arnd@arndb.de>
>> >> Cc: Grant Likely <grant.likely@linaro.org>
>> >> Cc: Rob Herring <robh+dt@kernel.org>
>> >> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> >> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
>> >> ---
>>
>> [...]
>>
>> >> +int of_pci_get_host_bridge_resources(struct device_node *dev,
>> >> +                  unsigned char busno, unsigned char bus_max,
>> >> +                  struct list_head *resources, resource_size_t *io_base)
>> >> +{
>> >> +  struct resource *res;
>> >> +  struct resource *bus_range;
>> >> +  struct of_pci_range range;
>> >> +  struct of_pci_range_parser parser;
>> >> +  char range_type[4];
>> >> +  int err;
>> >> +
>> >> +  if (!io_base)
>> >> +          return -EINVAL;
>> >> +  *io_base = OF_BAD_ADDR;
>> >> +
>> >> +  bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
>>
>> This function does a lot of kalloc's but there is not an easy way to
>> undo those allocations. Hot unplug of a host bridge or probe error
>> handling would leak memory.
>>
>> You could pass in struct device and use the devm_ variant (also
>> addressing Bjorn's comment), but not having an uninit/remove function
>> make what clean-up drivers have to do error prone. For example, on
>> uninit a driver needs to call pci_free_resource_list.
>
> If the function fails to parse the ranges for whatever reason it will
> call pci_free_resource_list on the resources that have been added already
> and it will clean up. If it is successful, then it is the job of the caller
> to free the list, as mentioned in the comment associated with the function.
>
> The reason why I am reluctant to use devm_ here is that the ranges are only
> parsed here, no filtering is applied. Architectures and/or host bridge
> drivers can/could impose additional restrictions to the list before passing
> it to pci_scan_root_bus() for example.

Okay, as long as the caller has a single clean-up responsibility, I
guess it is fine.

Rob
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diff mbox

Patch

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 7eaeac2..c18b8da 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -1,7 +1,9 @@ 
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_pci.h>
+#include <linux/slab.h>
 
 #include "of_private.h"
 
@@ -151,6 +153,112 @@  int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
 }
 EXPORT_SYMBOL_GPL(of_pci_get_domain_nr);
 
+/**
+ * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
+ * @dev: device node of the host bridge having the range property
+ * @busno: bus number associated with the bridge root bus
+ * @bus_max: maximum number of busses for this bridge
+ * @resources: list where the range of resources will be added after DT parsing
+ * @io_base: pointer to a variable that will contain on return the physical
+ * address for the start of the I/O range.
+ *
+ * It is the callers job to free the @resources list.
+ *
+ * This function will parse the "ranges" property of a PCI host bridge device
+ * node and setup the resource mapping based on its content. It is expected
+ * that the property conforms with the Power ePAPR document.
+ *
+ * It returns zero if the range parsing has been successful or a standard error
+ * value if it failed.
+ */
+int of_pci_get_host_bridge_resources(struct device_node *dev,
+			unsigned char busno, unsigned char bus_max,
+			struct list_head *resources, resource_size_t *io_base)
+{
+	struct resource *res;
+	struct resource *bus_range;
+	struct of_pci_range range;
+	struct of_pci_range_parser parser;
+	char range_type[4];
+	int err;
+
+	if (!io_base)
+		return -EINVAL;
+	*io_base = OF_BAD_ADDR;
+
+	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
+	if (!bus_range)
+		return -ENOMEM;
+
+	pr_info("PCI host bridge %s ranges:\n", dev->full_name);
+
+	err = of_pci_parse_bus_range(dev, bus_range);
+	if (err) {
+		bus_range->start = busno;
+		bus_range->end = bus_max;
+		bus_range->flags = IORESOURCE_BUS;
+		pr_info("  No bus range found for %s, using %pR\n",
+			dev->full_name, &bus_range);
+	} else {
+		if (bus_range->end > bus_range->start + bus_max)
+			bus_range->end = bus_range->start + bus_max;
+	}
+	pci_add_resource(resources, bus_range);
+
+	/* Check for ranges property */
+	err = of_pci_range_parser_init(&parser, dev);
+	if (err)
+		goto parse_failed;
+
+	pr_debug("Parsing ranges property...\n");
+	for_each_of_pci_range(&parser, &range) {
+		/* Read next ranges element */
+		if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
+			snprintf(range_type, 4, " IO");
+		else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
+			snprintf(range_type, 4, "MEM");
+		else
+			snprintf(range_type, 4, "err");
+		pr_info("  %s %#010llx..%#010llx -> %#010llx\n", range_type,
+			range.cpu_addr, range.cpu_addr + range.size - 1,
+			range.pci_addr);
+
+		/*
+		 * If we failed translation or got a zero-sized region
+		 * then skip this range
+		 */
+		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
+			continue;
+
+		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+		if (!res) {
+			err = -ENOMEM;
+			goto parse_failed;
+		}
+
+		err = of_pci_range_to_resource(&range, dev, res);
+		if (err) {
+			kfree(res);
+			goto parse_failed;
+		}
+
+		if (resource_type(res) == IORESOURCE_IO) {
+			if (*io_base != OF_BAD_ADDR)
+				pr_warn("More than one I/O resource converted. CPU offset for old range lost!\n");
+			*io_base = range.cpu_addr;
+		}
+
+		pci_add_resource_offset(resources, res,	res->start - range.pci_addr);
+	}
+
+	return 0;
+
+parse_failed:
+	pci_free_resource_list(resources);
+	return err;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
+
 #ifdef CONFIG_PCI_MSI
 
 static LIST_HEAD(of_pci_msi_chip_list);
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 3a3824c..a4b8a85 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -16,6 +16,10 @@  int of_pci_get_devfn(struct device_node *np);
 int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
 int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
 int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing);
+int of_pci_get_host_bridge_resources(struct device_node *dev,
+			unsigned char busno, unsigned char bus_max,
+			struct list_head *resources, resource_size_t *io_base);
+
 #else
 static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
 {
@@ -50,6 +54,13 @@  of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
 {
 	return -1;
 }
+
+int of_pci_get_host_bridge_resources(struct device_node *dev,
+			unsigned char busno, unsigned char bus_max,
+			struct list_head *resources, resource_size_t *io_base);
+{
+	return -EINVAL;
+}
 #endif
 
 #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)