diff mbox

[v6,06/30] PCI: Combine PCI domain and bus number in u32 arg

Message ID 1425868467-9667-7-git-send-email-wangyijing@huawei.com (mailing list archive)
State New, archived
Headers show

Commit Message

Yijing Wang March 9, 2015, 2:34 a.m. UTC
Currently, we use int type for bus number in
pci_create_root_bus(), pci_scan_root_bus() and
pci_scan_bus_legacy. Because PCI bus number
always <= 255, so we could change the bus number
argument type to u32, and combine PCI domain and
bus number in one. Also add a domain member in
pci_host_bridge to save domain number. Finally,
we could eliminate lots of the platform specific
pci_domain_nr() in the last of the series.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/probe.c      |   16 +++++++++-------
 include/linux/pci.h      |    7 ++++---
 include/uapi/linux/pci.h |    3 +++
 3 files changed, 16 insertions(+), 10 deletions(-)

Comments

Bjorn Helgaas March 12, 2015, 1:29 a.m. UTC | #1
On Mon, Mar 09, 2015 at 10:34:03AM +0800, Yijing Wang wrote:
> Currently, we use int type for bus number in
> pci_create_root_bus(), pci_scan_root_bus() and
> pci_scan_bus_legacy. Because PCI bus number
> always <= 255, so we could change the bus number
> argument type to u32, and combine PCI domain and
> bus number in one. 

This makes no sense.  Or rather, it only states the obvious: an 8-bit value
and a 16-bit value will both fit in a 32-bit value.  But it doesn't say
*why* you think it's a good idea to pass a single value that contains both
domain and bus numbers.  The obvious thing is to pass two separate values,
and you don't say why passing a single combined value is better.

Also see whitespace mistakes below.  I get a little testy when people don't
follow the whitespace convention of neighboring lines because if people are
sloppy about whitespace I assume they're sloppy about the code.

> Also add a domain member in
> pci_host_bridge to save domain number. Finally,
> we could eliminate lots of the platform specific
> pci_domain_nr() in the last of the series.
> 
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
>  drivers/pci/probe.c      |   16 +++++++++-------
>  include/linux/pci.h      |    7 ++++---
>  include/uapi/linux/pci.h |    3 +++
>  3 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 187fa54..3d6befd 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1890,7 +1890,7 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
>  {
>  }
>  
> -struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>  		struct pci_ops *ops, void *sysdata, struct list_head *resources)
>  {
>  	int error;
> @@ -1901,6 +1901,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  	resource_size_t offset;
>  	char bus_addr[64];
>  	char *fmt;
> +	u8	bus = PCI_BUSNUM(db);

Whitespace botch.

>  
>  	b = pci_alloc_bus(NULL);
>  	if (!b)
> @@ -1921,6 +1922,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  	if (!bridge)
>  		goto err_out;
>  
> +	bridge->domain = PCI_DOMAIN(db);
>  	bridge->dev.parent = parent;
>  	bridge->dev.release = pci_release_host_bridge_dev;
>  	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
> @@ -2058,7 +2060,7 @@ void pci_bus_release_busn_res(struct pci_bus *b)
>  			res, ret ? "can not be" : "is");
>  }
>  
> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>  		struct pci_ops *ops, void *sysdata, struct list_head *resources)
>  {
>  	struct resource_entry *window;
> @@ -2072,15 +2074,15 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>  			break;
>  		}
>  
> -	b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
> +	b = pci_create_root_bus(parent, db, ops, sysdata, resources);
>  	if (!b)
>  		return NULL;
>  
>  	if (!found) {
>  		dev_info(&b->dev,
>  		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
> -			bus);
> -		pci_bus_insert_busn_res(b, bus, 255);
> +			PCI_BUSNUM(db));
> +		pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
>  	}
>  
>  	max = pci_scan_child_bus(b);
> @@ -2092,7 +2094,7 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>  }
>  EXPORT_SYMBOL(pci_scan_root_bus);
>  
> -struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
> +struct pci_bus *pci_scan_bus(u32 db, struct pci_ops *ops,
>  					void *sysdata)
>  {
>  	LIST_HEAD(resources);
> @@ -2101,7 +2103,7 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
>  	pci_add_resource(&resources, &ioport_resource);
>  	pci_add_resource(&resources, &iomem_resource);
>  	pci_add_resource(&resources, &busn_resource);
> -	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
> +	b = pci_create_root_bus(NULL, db, ops, sysdata, &resources);
>  	if (b) {
>  		pci_scan_child_bus(b);
>  	} else {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 36effb8..8b3d245 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -401,6 +401,7 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
>  }
>  
>  struct pci_host_bridge {
> +	u16	domain;

Please follow the existing whitespace convention, i.e., use a space, not a
tab, between "u16 domain".

>  	struct device dev;
>  	struct pci_bus *bus;		/* root bus */
>  	struct list_head windows;	/* resource_entry */
> @@ -769,14 +770,14 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
>  void pcibios_scan_specific_bus(int busn);
>  struct pci_bus *pci_find_bus(int domain, int busnr);
>  void pci_bus_add_devices(const struct pci_bus *bus);
> -struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
> -struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_scan_bus(u32 dombus, struct pci_ops *ops, void *sysdata);
> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 dombus,
>  				    struct pci_ops *ops, void *sysdata,
>  				    struct list_head *resources);
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>  int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>  void pci_bus_release_busn_res(struct pci_bus *b);
> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 dombus,
>  					     struct pci_ops *ops, void *sysdata,
>  					     struct list_head *resources);
>  struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
> diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h
> index 3c292bc..89c6f15 100644
> --- a/include/uapi/linux/pci.h
> +++ b/include/uapi/linux/pci.h
> @@ -30,6 +30,9 @@
>  #define PCI_DEVFN(slot, func)	((((slot) & 0x1f) << 3) | ((func) & 0x07))
>  #define PCI_SLOT(devfn)		(((devfn) >> 3) & 0x1f)
>  #define PCI_FUNC(devfn)		((devfn) & 0x07)
> +#define PCI_DOMAIN(db)		((db) >> 16)
> +#define PCI_BUSNUM(db)		((db) & 0xffff)
> +#define PCI_DOMBUS(domain, bus)		(((domain) << 16) | (bus))
>  
>  /* Ioctls for /proc/bus/pci/X/Y nodes. */
>  #define PCIIOC_BASE		('P' << 24 | 'C' << 16 | 'I' << 8)
> -- 
> 1.7.1
> 
> --
> 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
Yijing Wang March 12, 2015, 12:14 p.m. UTC | #2
On 2015/3/12 9:29, Bjorn Helgaas wrote:
> On Mon, Mar 09, 2015 at 10:34:03AM +0800, Yijing Wang wrote:
>> Currently, we use int type for bus number in
>> pci_create_root_bus(), pci_scan_root_bus() and
>> pci_scan_bus_legacy. Because PCI bus number
>> always <= 255, so we could change the bus number
>> argument type to u32, and combine PCI domain and
>> bus number in one. 
> 
> This makes no sense.  Or rather, it only states the obvious: an 8-bit value
> and a 16-bit value will both fit in a 32-bit value.  But it doesn't say
> *why* you think it's a good idea to pass a single value that contains both
> domain and bus numbers.  The obvious thing is to pass two separate values,
> and you don't say why passing a single combined value is better.

Sorry for my poor description for this patch, I combined the domain and bus, because
I think now we have too many args at pci_scan_root_bus() or other scan functions,

struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
		struct pci_ops *ops, void *sysdata, struct list_head *resources)

Now we have five args yet, plus the new introduced domain and pci_host_bridge_ops,
it will become 7.

I thought introduced a new structure which contain the necessary info to scan root bus/ host bridge,

E.g

struct pci_scan_info {
	int bus;
	struct device *parent;
	struct pci_ops *ops;
	void *sysdata;
	struct list_head *resource;
	int domain;
	struct pci_host_bridge_ops;
}

Do you like this one or keep it like now ?

pci_scan_root_bus(struct device *parent, int domain, int bus,
		struct pci_ops *ops, void *sysdata, struct list_head *resources, struct pci_host_bridge_ops *ops)


> 
> Also see whitespace mistakes below.  I get a little testy when people don't
> follow the whitespace convention of neighboring lines because if people are
> sloppy about whitespace I assume they're sloppy about the code.
> 

Sorry, I would be more careful.


>>  	int error;
>> @@ -1901,6 +1901,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>  	resource_size_t offset;
>>  	char bus_addr[64];
>>  	char *fmt;
>> +	u8	bus = PCI_BUSNUM(db);
> 
> Whitespace botch.
> 
>>  
>>  	b = pci_alloc_bus(NULL);
>>  	if (!b)
>> @@ -1921,6 +1922,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>  	if (!bridge)
>>  		goto err_out;
>>  
>> +	bridge->domain = PCI_DOMAIN(db);
>>  	bridge->dev.parent = parent;
>>  	bridge->dev.release = pci_release_host_bridge_dev;
>>  	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>> @@ -2058,7 +2060,7 @@ void pci_bus_release_busn_res(struct pci_bus *b)
>>  			res, ret ? "can not be" : "is");
>>  }
>>  
>> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>>  		struct pci_ops *ops, void *sysdata, struct list_head *resources)
>>  {
>>  	struct resource_entry *window;
>> @@ -2072,15 +2074,15 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>>  			break;
>>  		}
>>  
>> -	b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
>> +	b = pci_create_root_bus(parent, db, ops, sysdata, resources);
>>  	if (!b)
>>  		return NULL;
>>  
>>  	if (!found) {
>>  		dev_info(&b->dev,
>>  		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
>> -			bus);
>> -		pci_bus_insert_busn_res(b, bus, 255);
>> +			PCI_BUSNUM(db));
>> +		pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
>>  	}
>>  
>>  	max = pci_scan_child_bus(b);
>> @@ -2092,7 +2094,7 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>>  }
>>  EXPORT_SYMBOL(pci_scan_root_bus);
>>  
>> -struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
>> +struct pci_bus *pci_scan_bus(u32 db, struct pci_ops *ops,
>>  					void *sysdata)
>>  {
>>  	LIST_HEAD(resources);
>> @@ -2101,7 +2103,7 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
>>  	pci_add_resource(&resources, &ioport_resource);
>>  	pci_add_resource(&resources, &iomem_resource);
>>  	pci_add_resource(&resources, &busn_resource);
>> -	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
>> +	b = pci_create_root_bus(NULL, db, ops, sysdata, &resources);
>>  	if (b) {
>>  		pci_scan_child_bus(b);
>>  	} else {
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 36effb8..8b3d245 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -401,6 +401,7 @@ static inline int pci_channel_offline(struct pci_dev *pdev)
>>  }
>>  
>>  struct pci_host_bridge {
>> +	u16	domain;
> 
> Please follow the existing whitespace convention, i.e., use a space, not a
> tab, between "u16 domain".
> 
>>  	struct device dev;
>>  	struct pci_bus *bus;		/* root bus */
>>  	struct list_head windows;	/* resource_entry */
>> @@ -769,14 +770,14 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
>>  void pcibios_scan_specific_bus(int busn);
>>  struct pci_bus *pci_find_bus(int domain, int busnr);
>>  void pci_bus_add_devices(const struct pci_bus *bus);
>> -struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
>> -struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>> +struct pci_bus *pci_scan_bus(u32 dombus, struct pci_ops *ops, void *sysdata);
>> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 dombus,
>>  				    struct pci_ops *ops, void *sysdata,
>>  				    struct list_head *resources);
>>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>>  int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>>  void pci_bus_release_busn_res(struct pci_bus *b);
>> -struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>> +struct pci_bus *pci_scan_root_bus(struct device *parent, u32 dombus,
>>  					     struct pci_ops *ops, void *sysdata,
>>  					     struct list_head *resources);
>>  struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
>> diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h
>> index 3c292bc..89c6f15 100644
>> --- a/include/uapi/linux/pci.h
>> +++ b/include/uapi/linux/pci.h
>> @@ -30,6 +30,9 @@
>>  #define PCI_DEVFN(slot, func)	((((slot) & 0x1f) << 3) | ((func) & 0x07))
>>  #define PCI_SLOT(devfn)		(((devfn) >> 3) & 0x1f)
>>  #define PCI_FUNC(devfn)		((devfn) & 0x07)
>> +#define PCI_DOMAIN(db)		((db) >> 16)
>> +#define PCI_BUSNUM(db)		((db) & 0xffff)
>> +#define PCI_DOMBUS(domain, bus)		(((domain) << 16) | (bus))
>>  
>>  /* Ioctls for /proc/bus/pci/X/Y nodes. */
>>  #define PCIIOC_BASE		('P' << 24 | 'C' << 16 | 'I' << 8)
>> -- 
>> 1.7.1
>>
>> --
>> 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
> 
> .
>
Bjorn Helgaas March 12, 2015, 7:49 p.m. UTC | #3
On Thu, Mar 12, 2015 at 08:14:40PM +0800, Yijing Wang wrote:
> On 2015/3/12 9:29, Bjorn Helgaas wrote:
> > On Mon, Mar 09, 2015 at 10:34:03AM +0800, Yijing Wang wrote:
> >> Currently, we use int type for bus number in
> >> pci_create_root_bus(), pci_scan_root_bus() and
> >> pci_scan_bus_legacy. Because PCI bus number
> >> always <= 255, so we could change the bus number
> >> argument type to u32, and combine PCI domain and
> >> bus number in one. 
> > 
> > This makes no sense.  Or rather, it only states the obvious: an 8-bit value
> > and a 16-bit value will both fit in a 32-bit value.  But it doesn't say
> > *why* you think it's a good idea to pass a single value that contains both
> > domain and bus numbers.  The obvious thing is to pass two separate values,
> > and you don't say why passing a single combined value is better.
> 
> Sorry for my poor description for this patch, I combined the domain and bus, because
> I think now we have too many args at pci_scan_root_bus() or other scan functions,
> 
> struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
> 		struct pci_ops *ops, void *sysdata, struct list_head *resources)
> 
> Now we have five args yet, plus the new introduced domain and pci_host_bridge_ops,
> it will become 7.
> 
> I thought introduced a new structure which contain the necessary info to scan root bus/ host bridge,
> 
> E.g
> 
> struct pci_scan_info {
> 	int bus;
> 	struct device *parent;
> 	struct pci_ops *ops;
> 	void *sysdata;
> 	struct list_head *resource;
> 	int domain;
> 	struct pci_host_bridge_ops;
> }
> 
> Do you like this one or keep it like now ?
> 
> pci_scan_root_bus(struct device *parent, int domain, int bus,
> 		struct pci_ops *ops, void *sysdata, struct list_head *resources, struct pci_host_bridge_ops *ops)

I don't think reducing the number of arguments is a good argument for
squashing some of them together.

I don't really want to add a structure like that because it adds management
complexity for all the callers because it contains per-bridge things (bus,
parent, domain, resource, sysdata).  Things like struct pci_ops and struct
pci_host_bridge_ops are much simpler because drivers can statically
allocate a single copy and use it for multiple devices.

I think it might make sense to put the struct pci_ops pointer inside struct
pci_host_bridge_ops.  That would get rid of one of the arguments.

You might also be able to get rid of the "bus" argument, since the caller
should be passing an IORESOURCE_BUS resource in the resource list, and
"bus" should be the same as res->start.

Bjorn
Yijing Wang March 13, 2015, 3:19 a.m. UTC | #4
>> struct pci_scan_info {
>> 	int bus;
>> 	struct device *parent;
>> 	struct pci_ops *ops;
>> 	void *sysdata;
>> 	struct list_head *resource;
>> 	int domain;
>> 	struct pci_host_bridge_ops;
>> }
>>
>> Do you like this one or keep it like now ?
>>
>> pci_scan_root_bus(struct device *parent, int domain, int bus,
>> 		struct pci_ops *ops, void *sysdata, struct list_head *resources, struct pci_host_bridge_ops *ops)
> 
> I don't think reducing the number of arguments is a good argument for
> squashing some of them together.
> 
> I don't really want to add a structure like that because it adds management
> complexity for all the callers because it contains per-bridge things (bus,
> parent, domain, resource, sysdata).  Things like struct pci_ops and struct
> pci_host_bridge_ops are much simpler because drivers can statically
> allocate a single copy and use it for multiple devices.
> 
> I think it might make sense to put the struct pci_ops pointer inside struct
> pci_host_bridge_ops.  That would get rid of one of the arguments.
> 
> You might also be able to get rid of the "bus" argument, since the caller
> should be passing an IORESOURCE_BUS resource in the resource list, and
> "bus" should be the same as res->start.

I think this make sense, I will try to find a better solution.

Thanks!
Yijing.

> 
> Bjorn
> 
> .
>
diff mbox

Patch

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 187fa54..3d6befd 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1890,7 +1890,7 @@  void __weak pcibios_remove_bus(struct pci_bus *bus)
 {
 }
 
-struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
+struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
 		struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {
 	int error;
@@ -1901,6 +1901,7 @@  struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	resource_size_t offset;
 	char bus_addr[64];
 	char *fmt;
+	u8	bus = PCI_BUSNUM(db);
 
 	b = pci_alloc_bus(NULL);
 	if (!b)
@@ -1921,6 +1922,7 @@  struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	if (!bridge)
 		goto err_out;
 
+	bridge->domain = PCI_DOMAIN(db);
 	bridge->dev.parent = parent;
 	bridge->dev.release = pci_release_host_bridge_dev;
 	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
@@ -2058,7 +2060,7 @@  void pci_bus_release_busn_res(struct pci_bus *b)
 			res, ret ? "can not be" : "is");
 }
 
-struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
+struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
 		struct pci_ops *ops, void *sysdata, struct list_head *resources)
 {
 	struct resource_entry *window;
@@ -2072,15 +2074,15 @@  struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
 			break;
 		}
 
-	b = pci_create_root_bus(parent, bus, ops, sysdata, resources);
+	b = pci_create_root_bus(parent, db, ops, sysdata, resources);
 	if (!b)
 		return NULL;
 
 	if (!found) {
 		dev_info(&b->dev,
 		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
-			bus);
-		pci_bus_insert_busn_res(b, bus, 255);
+			PCI_BUSNUM(db));
+		pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
 	}
 
 	max = pci_scan_child_bus(b);
@@ -2092,7 +2094,7 @@  struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
 }
 EXPORT_SYMBOL(pci_scan_root_bus);
 
-struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
+struct pci_bus *pci_scan_bus(u32 db, struct pci_ops *ops,
 					void *sysdata)
 {
 	LIST_HEAD(resources);
@@ -2101,7 +2103,7 @@  struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
 	pci_add_resource(&resources, &ioport_resource);
 	pci_add_resource(&resources, &iomem_resource);
 	pci_add_resource(&resources, &busn_resource);
-	b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
+	b = pci_create_root_bus(NULL, db, ops, sysdata, &resources);
 	if (b) {
 		pci_scan_child_bus(b);
 	} else {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 36effb8..8b3d245 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -401,6 +401,7 @@  static inline int pci_channel_offline(struct pci_dev *pdev)
 }
 
 struct pci_host_bridge {
+	u16	domain;
 	struct device dev;
 	struct pci_bus *bus;		/* root bus */
 	struct list_head windows;	/* resource_entry */
@@ -769,14 +770,14 @@  void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
 void pcibios_scan_specific_bus(int busn);
 struct pci_bus *pci_find_bus(int domain, int busnr);
 void pci_bus_add_devices(const struct pci_bus *bus);
-struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
-struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
+struct pci_bus *pci_scan_bus(u32 dombus, struct pci_ops *ops, void *sysdata);
+struct pci_bus *pci_create_root_bus(struct device *parent, u32 dombus,
 				    struct pci_ops *ops, void *sysdata,
 				    struct list_head *resources);
 int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
 int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
 void pci_bus_release_busn_res(struct pci_bus *b);
-struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
+struct pci_bus *pci_scan_root_bus(struct device *parent, u32 dombus,
 					     struct pci_ops *ops, void *sysdata,
 					     struct list_head *resources);
 struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h
index 3c292bc..89c6f15 100644
--- a/include/uapi/linux/pci.h
+++ b/include/uapi/linux/pci.h
@@ -30,6 +30,9 @@ 
 #define PCI_DEVFN(slot, func)	((((slot) & 0x1f) << 3) | ((func) & 0x07))
 #define PCI_SLOT(devfn)		(((devfn) >> 3) & 0x1f)
 #define PCI_FUNC(devfn)		((devfn) & 0x07)
+#define PCI_DOMAIN(db)		((db) >> 16)
+#define PCI_BUSNUM(db)		((db) & 0xffff)
+#define PCI_DOMBUS(domain, bus)		(((domain) << 16) | (bus))
 
 /* Ioctls for /proc/bus/pci/X/Y nodes. */
 #define PCIIOC_BASE		('P' << 24 | 'C' << 16 | 'I' << 8)