Patchwork [V6,1/2] PCI/ACPI: Provide acpi_get_rc_resources() for ARM64 platform

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Submitter Dongdong Liu
Date Nov. 22, 2016, 12:08 p.m.
Message ID <1479816529-97410-2-git-send-email-liudongdong3@huawei.com>
Download mbox | patch
Permalink /patch/118973/
State New
Headers show

Comments

Dongdong Liu - Nov. 22, 2016, 12:08 p.m.
The acpi_get_rc_resources() is used to get the RC register address that can
not be described in MCFG. It takes the _HID&segment to look for and returns
the RC address resource. Use PNP0C02 devices to describe such RC address
resource. Use _UID to match segment to tell which root bus the PNP0C02
resource belong to.

Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
---
 drivers/pci/pci-acpi.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h      |  4 +++
 2 files changed, 73 insertions(+)
Tomasz Nowicki - Nov. 22, 2016, 12:32 p.m.
Hi Dongdong,

On 22.11.2016 13:08, Dongdong Liu wrote:
> The acpi_get_rc_resources() is used to get the RC register address that can
> not be described in MCFG. It takes the _HID&segment to look for and returns
> the RC address resource. Use PNP0C02 devices to describe such RC address
> resource. Use _UID to match segment to tell which root bus the PNP0C02
> resource belong to.
>
> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> ---
>  drivers/pci/pci-acpi.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h      |  4 +++
>  2 files changed, 73 insertions(+)
>
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index d966d47..76fd6f4 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -29,6 +29,75 @@
>  	0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
>  };
>
> +#ifdef CONFIG_ARM64
> +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
> +{
> +	struct resource_entry *entry;
> +	struct list_head list;
> +	unsigned long flags;
> +	int ret;
> +	struct resource *res;
> +
> +	INIT_LIST_HEAD(&list);
> +	flags = IORESOURCE_MEM;
> +	ret = acpi_dev_get_resources(adev, &list,
> +				     acpi_dev_filter_resource_type_cb,
> +				     (void *) flags);
> +	if (ret <= 0)
> +		return NULL;
> +
> +	entry = list_first_entry(&list, struct resource_entry, node);
> +	res = entry->res;

You return "res" memory pointer and...

> +	acpi_dev_free_resource_list(&list);

free it here.

> +	return res;
> +}


We either allocate memory for res here or get it from the caller.

Tomasz
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Lorenzo Pieralisi - Nov. 22, 2016, 3:56 p.m.
On Tue, Nov 22, 2016 at 08:08:48PM +0800, Dongdong Liu wrote:
> The acpi_get_rc_resources() is used to get the RC register address that can
> not be described in MCFG. It takes the _HID&segment to look for and returns
> the RC address resource. Use PNP0C02 devices to describe such RC address
> resource. Use _UID to match segment to tell which root bus the PNP0C02
> resource belong to.

Here (ie interpreting the _UID as a segment identifier) is where we
start interpreting the specs instead of relying on them, if you want to
go ahead with this feel free but I do not like this attitude at all.

> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> ---
>  drivers/pci/pci-acpi.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h      |  4 +++
>  2 files changed, 73 insertions(+)
> 
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index d966d47..76fd6f4 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -29,6 +29,75 @@
>  	0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
>  };
>  
> +#ifdef CONFIG_ARM64

CONFIG_PCI_ECAM_QUIRKS (that you will introduce earlier in your series).

The way you did it seems to imply that on ARM64 to get RC address we
need to (and are allowed to) use this function (and related, *Linux
specific*, ACPI bindings) and that's a generic way of getting config
space. It is not and it must not be and I consider it a bit of a stretch
to have it in generic code but I can live with that as long as it comes
with its own config option that describes that this stuff is
non-compliant code used by non-compliant platform drivers.

Thanks,
Lorenzo

> +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
> +{
> +	struct resource_entry *entry;
> +	struct list_head list;
> +	unsigned long flags;
> +	int ret;
> +	struct resource *res;
> +
> +	INIT_LIST_HEAD(&list);
> +	flags = IORESOURCE_MEM;
> +	ret = acpi_dev_get_resources(adev, &list,
> +				     acpi_dev_filter_resource_type_cb,
> +				     (void *) flags);
> +	if (ret <= 0)
> +		return NULL;
> +
> +	entry = list_first_entry(&list, struct resource_entry, node);
> +	res = entry->res;
> +	acpi_dev_free_resource_list(&list);
> +	return res;
> +}
> +
> +static acpi_status acpi_match_rc(acpi_handle handle, u32 lvl, void *context,
> +				 void **retval)
> +{
> +	u16 *segment = context;
> +	unsigned long long uid;
> +	acpi_status status;
> +
> +	status = acpi_evaluate_integer(handle, "_UID", NULL, &uid);
> +	if (ACPI_FAILURE(status) || uid != *segment)
> +		return AE_CTRL_DEPTH;
> +
> +	*(acpi_handle *)retval = handle;
> +	return AE_CTRL_TERMINATE;
> +}
> +
> +/**
> + * acpi_get_rc_resources() - get the RC address resource.
> + * @hid:	HID to search for.
> + * @segment:	PCI Segment number.
> + *
> + * Get the RC address resource that can not be described in MCFG. It takes
> + * the _HID&segment to look for and returns the RC address resource. Use
> + * _CRS of PNP0C02 devices to describe such RC address resource. Use _UID
> + * to match segment to tell which root bus the PNP0C02 resource belong to.
> + *
> + * Return: RC address resource.
> + */
> +struct resource *acpi_get_rc_resources(const char *hid, u16 segment)
> +{
> +	struct acpi_device *adev;
> +	acpi_status status;
> +	acpi_handle handle;
> +	int ret;
> +
> +	status = acpi_get_devices(hid, acpi_match_rc, &segment, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	ret = acpi_bus_get_device(handle, &adev);
> +	if (ret)
> +		return ret;
> +
> +	return acpi_get_rc_addr(adev);
> +}
> +#endif
> +
>  phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
>  {
>  	acpi_status status = AE_NOT_EXIST;
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 4518562..bf1dbfe 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -356,4 +356,8 @@ static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe)
>  }
>  #endif
>  
> +#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
> +struct resource *acpi_get_rc_resources(const char *hid, u16 segment);
> +#endif
> +
>  #endif /* DRIVERS_PCI_H */
> -- 
> 1.9.1
> 
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Gabriele Paoloni - Nov. 22, 2016, 4:09 p.m.
Hi Lorenzo

Thanks for reviewing

> -----Original Message-----
> From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@arm.com]
> Sent: 22 November 2016 15:57
> To: liudongdong (C)
> Cc: helgaas@kernel.org; arnd@arndb.de; rafael@kernel.org;
> tn@semihalf.com; Wangzhou (B); pratyush.anand@gmail.com; linux-
> pci@vger.kernel.org; linux-acpi@vger.kernel.org; linux-
> kernel@vger.kernel.org; jcm@redhat.com; Gabriele Paoloni; Chenxin
> (Charles); hanjun.guo@linaro.org; Linuxarm
> Subject: Re: [PATCH V6 1/2] PCI/ACPI: Provide acpi_get_rc_resources()
> for ARM64 platform
> 
> On Tue, Nov 22, 2016 at 08:08:48PM +0800, Dongdong Liu wrote:
> > The acpi_get_rc_resources() is used to get the RC register address
> that can
> > not be described in MCFG. It takes the _HID&segment to look for and
> returns
> > the RC address resource. Use PNP0C02 devices to describe such RC
> address
> > resource. Use _UID to match segment to tell which root bus the
> PNP0C02
> > resource belong to.
> 
> Here (ie interpreting the _UID as a segment identifier) is where we
> start interpreting the specs instead of relying on them, if you want to
> go ahead with this feel free but I do not like this attitude at all.

Obviously there are no specs to specify the segment id of a quirk.
Looking at the ACPI specs it seems to me that the _UID is no worse
than other device identification objects...

Maybe we can use the _SUN as an alternative solution?

> 
> > Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> > Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> > ---
> >  drivers/pci/pci-acpi.c | 69
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/pci/pci.h      |  4 +++
> >  2 files changed, 73 insertions(+)
> >
> > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> > index d966d47..76fd6f4 100644
> > --- a/drivers/pci/pci-acpi.c
> > +++ b/drivers/pci/pci-acpi.c
> > @@ -29,6 +29,75 @@
> >  	0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
> >  };
> >
> > +#ifdef CONFIG_ARM64
> 
> CONFIG_PCI_ECAM_QUIRKS (that you will introduce earlier in your
> series).
> 
> The way you did it seems to imply that on ARM64 to get RC address we
> need to (and are allowed to) use this function (and related, *Linux
> specific*, ACPI bindings) and that's a generic way of getting config
> space. It is not and it must not be and I consider it a bit of a
> stretch
> to have it in generic code but I can live with that as long as it comes
> with its own config option that describes that this stuff is
> non-compliant code used by non-compliant platform drivers.

Yes probably better to have

#ifdef CONFIG_PCI_ECAM_QUIRKS

Thanks

Gab

> 
> Thanks,
> Lorenzo
> 
> > +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
> > +{
> > +	struct resource_entry *entry;
> > +	struct list_head list;
> > +	unsigned long flags;
> > +	int ret;
> > +	struct resource *res;
> > +
> > +	INIT_LIST_HEAD(&list);
> > +	flags = IORESOURCE_MEM;
> > +	ret = acpi_dev_get_resources(adev, &list,
> > +				     acpi_dev_filter_resource_type_cb,
> > +				     (void *) flags);
> > +	if (ret <= 0)
> > +		return NULL;
> > +
> > +	entry = list_first_entry(&list, struct resource_entry, node);
> > +	res = entry->res;
> > +	acpi_dev_free_resource_list(&list);
> > +	return res;
> > +}
> > +
> > +static acpi_status acpi_match_rc(acpi_handle handle, u32 lvl, void
> *context,
> > +				 void **retval)
> > +{
> > +	u16 *segment = context;
> > +	unsigned long long uid;
> > +	acpi_status status;
> > +
> > +	status = acpi_evaluate_integer(handle, "_UID", NULL, &uid);
> > +	if (ACPI_FAILURE(status) || uid != *segment)
> > +		return AE_CTRL_DEPTH;
> > +
> > +	*(acpi_handle *)retval = handle;
> > +	return AE_CTRL_TERMINATE;
> > +}
> > +
> > +/**
> > + * acpi_get_rc_resources() - get the RC address resource.
> > + * @hid:	HID to search for.
> > + * @segment:	PCI Segment number.
> > + *
> > + * Get the RC address resource that can not be described in MCFG. It
> takes
> > + * the _HID&segment to look for and returns the RC address resource.
> Use
> > + * _CRS of PNP0C02 devices to describe such RC address resource. Use
> _UID
> > + * to match segment to tell which root bus the PNP0C02 resource
> belong to.
> > + *
> > + * Return: RC address resource.
> > + */
> > +struct resource *acpi_get_rc_resources(const char *hid, u16 segment)
> > +{
> > +	struct acpi_device *adev;
> > +	acpi_status status;
> > +	acpi_handle handle;
> > +	int ret;
> > +
> > +	status = acpi_get_devices(hid, acpi_match_rc, &segment, &handle);
> > +	if (ACPI_FAILURE(status))
> > +		return -ENODEV;
> > +
> > +	ret = acpi_bus_get_device(handle, &adev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return acpi_get_rc_addr(adev);
> > +}
> > +#endif
> > +
> >  phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
> >  {
> >  	acpi_status status = AE_NOT_EXIST;
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index 4518562..bf1dbfe 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -356,4 +356,8 @@ static inline int pci_dev_specific_reset(struct
> pci_dev *dev, int probe)
> >  }
> >  #endif
> >
> > +#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
> > +struct resource *acpi_get_rc_resources(const char *hid, u16
> segment);
> > +#endif
> > +
> >  #endif /* DRIVERS_PCI_H */
> > --
> > 1.9.1
> >
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Lorenzo Pieralisi - Nov. 22, 2016, 5:03 p.m.
On Tue, Nov 22, 2016 at 04:09:57PM +0000, Gabriele Paoloni wrote:

[...]

> > On Tue, Nov 22, 2016 at 08:08:48PM +0800, Dongdong Liu wrote:
> > > The acpi_get_rc_resources() is used to get the RC register address
> > that can
> > > not be described in MCFG. It takes the _HID&segment to look for and
> > returns
> > > the RC address resource. Use PNP0C02 devices to describe such RC
> > address
> > > resource. Use _UID to match segment to tell which root bus the
> > PNP0C02
> > > resource belong to.
> > 
> > Here (ie interpreting the _UID as a segment identifier) is where we
> > start interpreting the specs instead of relying on them, if you want to
> > go ahead with this feel free but I do not like this attitude at all.
> 
> Obviously there are no specs to specify the segment id of a quirk.

That's the reason why _UID (or any other standard object) should not be
(ab)used to do that, again, that's just my opinion.

> Looking at the ACPI specs it seems to me that the _UID is no worse
> than other device identification objects...

There are no bindings in the specs describing what you need. If you want
to say "for this _HID, _UID means something completely different
- ie root bridge segment identifier - go ahead if that's fine with Bjorn
and Rafael; another solution would be adding a _DSM/DSD to the PNP0c02
device to retrieve the segment number, other than that I have run out
of ideas.

Lorenzo

> 
> > 
> > > Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> > > Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> > > ---
> > >  drivers/pci/pci-acpi.c | 69
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  drivers/pci/pci.h      |  4 +++
> > >  2 files changed, 73 insertions(+)
> > >
> > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> > > index d966d47..76fd6f4 100644
> > > --- a/drivers/pci/pci-acpi.c
> > > +++ b/drivers/pci/pci-acpi.c
> > > @@ -29,6 +29,75 @@
> > >  	0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
> > >  };
> > >
> > > +#ifdef CONFIG_ARM64
> > 
> > CONFIG_PCI_ECAM_QUIRKS (that you will introduce earlier in your
> > series).
> > 
> > The way you did it seems to imply that on ARM64 to get RC address we
> > need to (and are allowed to) use this function (and related, *Linux
> > specific*, ACPI bindings) and that's a generic way of getting config
> > space. It is not and it must not be and I consider it a bit of a
> > stretch
> > to have it in generic code but I can live with that as long as it comes
> > with its own config option that describes that this stuff is
> > non-compliant code used by non-compliant platform drivers.
> 
> Yes probably better to have
> 
> #ifdef CONFIG_PCI_ECAM_QUIRKS
> 
> Thanks
> 
> Gab
> 
> > 
> > Thanks,
> > Lorenzo
> > 
> > > +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
> > > +{
> > > +	struct resource_entry *entry;
> > > +	struct list_head list;
> > > +	unsigned long flags;
> > > +	int ret;
> > > +	struct resource *res;
> > > +
> > > +	INIT_LIST_HEAD(&list);
> > > +	flags = IORESOURCE_MEM;
> > > +	ret = acpi_dev_get_resources(adev, &list,
> > > +				     acpi_dev_filter_resource_type_cb,
> > > +				     (void *) flags);
> > > +	if (ret <= 0)
> > > +		return NULL;
> > > +
> > > +	entry = list_first_entry(&list, struct resource_entry, node);
> > > +	res = entry->res;
> > > +	acpi_dev_free_resource_list(&list);
> > > +	return res;
> > > +}
> > > +
> > > +static acpi_status acpi_match_rc(acpi_handle handle, u32 lvl, void
> > *context,
> > > +				 void **retval)
> > > +{
> > > +	u16 *segment = context;
> > > +	unsigned long long uid;
> > > +	acpi_status status;
> > > +
> > > +	status = acpi_evaluate_integer(handle, "_UID", NULL, &uid);
> > > +	if (ACPI_FAILURE(status) || uid != *segment)
> > > +		return AE_CTRL_DEPTH;
> > > +
> > > +	*(acpi_handle *)retval = handle;
> > > +	return AE_CTRL_TERMINATE;
> > > +}
> > > +
> > > +/**
> > > + * acpi_get_rc_resources() - get the RC address resource.
> > > + * @hid:	HID to search for.
> > > + * @segment:	PCI Segment number.
> > > + *
> > > + * Get the RC address resource that can not be described in MCFG. It
> > takes
> > > + * the _HID&segment to look for and returns the RC address resource.
> > Use
> > > + * _CRS of PNP0C02 devices to describe such RC address resource. Use
> > _UID
> > > + * to match segment to tell which root bus the PNP0C02 resource
> > belong to.
> > > + *
> > > + * Return: RC address resource.
> > > + */
> > > +struct resource *acpi_get_rc_resources(const char *hid, u16 segment)
> > > +{
> > > +	struct acpi_device *adev;
> > > +	acpi_status status;
> > > +	acpi_handle handle;
> > > +	int ret;
> > > +
> > > +	status = acpi_get_devices(hid, acpi_match_rc, &segment, &handle);
> > > +	if (ACPI_FAILURE(status))
> > > +		return -ENODEV;
> > > +
> > > +	ret = acpi_bus_get_device(handle, &adev);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	return acpi_get_rc_addr(adev);
> > > +}
> > > +#endif
> > > +
> > >  phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
> > >  {
> > >  	acpi_status status = AE_NOT_EXIST;
> > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > > index 4518562..bf1dbfe 100644
> > > --- a/drivers/pci/pci.h
> > > +++ b/drivers/pci/pci.h
> > > @@ -356,4 +356,8 @@ static inline int pci_dev_specific_reset(struct
> > pci_dev *dev, int probe)
> > >  }
> > >  #endif
> > >
> > > +#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
> > > +struct resource *acpi_get_rc_resources(const char *hid, u16
> > segment);
> > > +#endif
> > > +
> > >  #endif /* DRIVERS_PCI_H */
> > > --
> > > 1.9.1
> > >
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Dongdong Liu - Nov. 23, 2016, 1:44 a.m.
Hi Tomasz

在 2016/11/22 20:32, Tomasz Nowicki 写道:
> Hi Dongdong,
>
> On 22.11.2016 13:08, Dongdong Liu wrote:
>> The acpi_get_rc_resources() is used to get the RC register address that can
>> not be described in MCFG. It takes the _HID&segment to look for and returns
>> the RC address resource. Use PNP0C02 devices to describe such RC address
>> resource. Use _UID to match segment to tell which root bus the PNP0C02
>> resource belong to.
>>
>> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
>> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
>> ---
>>  drivers/pci/pci-acpi.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/pci/pci.h      |  4 +++
>>  2 files changed, 73 insertions(+)
>>
>> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
>> index d966d47..76fd6f4 100644
>> --- a/drivers/pci/pci-acpi.c
>> +++ b/drivers/pci/pci-acpi.c
>> @@ -29,6 +29,75 @@
>>      0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
>>  };
>>
>> +#ifdef CONFIG_ARM64
>> +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
>> +{
>> +    struct resource_entry *entry;
>> +    struct list_head list;
>> +    unsigned long flags;
>> +    int ret;
>> +    struct resource *res;
>> +
>> +    INIT_LIST_HEAD(&list);
>> +    flags = IORESOURCE_MEM;
>> +    ret = acpi_dev_get_resources(adev, &list,
>> +                     acpi_dev_filter_resource_type_cb,
>> +                     (void *) flags);
>> +    if (ret <= 0)
>> +        return NULL;
>> +
>> +    entry = list_first_entry(&list, struct resource_entry, node);
>> +    res = entry->res;
>
> You return "res" memory pointer and...
>
>> +    acpi_dev_free_resource_list(&list);
>
> free it here.

  acpi_dev_free_resource_list
	--->resource_list_free
		--->resource_list_destroy_entry
			--->resource_list_free_entry
				--->kfree(entry)
only free entry not free entry->res, so this is ok.

Thanks
Dongdong
>
>> +    return res;
>> +}
>
>
> We either allocate memory for res here or get it from the caller.
>
> Tomasz
>
> .
>

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Dongdong Liu - Nov. 23, 2016, 2:24 a.m.
Hi Tomasz

在 2016/11/23 9:44, Dongdong Liu 写道:
> Hi Tomasz
>
> 在 2016/11/22 20:32, Tomasz Nowicki 写道:
>> Hi Dongdong,
>>
>> On 22.11.2016 13:08, Dongdong Liu wrote:
>>> The acpi_get_rc_resources() is used to get the RC register address that can
>>> not be described in MCFG. It takes the _HID&segment to look for and returns
>>> the RC address resource. Use PNP0C02 devices to describe such RC address
>>> resource. Use _UID to match segment to tell which root bus the PNP0C02
>>> resource belong to.
>>>
>>> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
>>> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
>>> ---
>>>  drivers/pci/pci-acpi.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  drivers/pci/pci.h      |  4 +++
>>>  2 files changed, 73 insertions(+)
>>>
>>> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
>>> index d966d47..76fd6f4 100644
>>> --- a/drivers/pci/pci-acpi.c
>>> +++ b/drivers/pci/pci-acpi.c
>>> @@ -29,6 +29,75 @@
>>>      0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
>>>  };
>>>
>>> +#ifdef CONFIG_ARM64
>>> +static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
>>> +{
>>> +    struct resource_entry *entry;
>>> +    struct list_head list;
>>> +    unsigned long flags;
>>> +    int ret;
>>> +    struct resource *res;
>>> +
>>> +    INIT_LIST_HEAD(&list);
>>> +    flags = IORESOURCE_MEM;
>>> +    ret = acpi_dev_get_resources(adev, &list,
>>> +                     acpi_dev_filter_resource_type_cb,
>>> +                     (void *) flags);
>>> +    if (ret <= 0)
>>> +        return NULL;
>>> +
>>> +    entry = list_first_entry(&list, struct resource_entry, node);
>>> +    res = entry->res;
>>
>> You return "res" memory pointer and...
>>
>>> +    acpi_dev_free_resource_list(&list);
>>
>> free it here.
>
>  acpi_dev_free_resource_list
>     --->resource_list_free
>         --->resource_list_destroy_entry
>             --->resource_list_free_entry
>                 --->kfree(entry)
> only free entry not free entry->res, so this is ok.

Sorry I am wrong, ignore this.
>
> Thanks
> Dongdong
>>
>>> +    return res;
>>> +}
>>
>>
>> We either allocate memory for res here or get it from the caller.

Yes, you are right.I prefer to get if from the caller as PATCH V5 shows.

Thanks
Dongdong
>>
>> Tomasz
>>
>> .
>>
>
> _______________________________________________
> linuxarm mailing list
> linuxarm@huawei.com
> http://rnd-openeuler.huawei.com/mailman/listinfo/linuxarm

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Patch

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index d966d47..76fd6f4 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -29,6 +29,75 @@ 
 	0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d
 };
 
+#ifdef CONFIG_ARM64
+static struct resource *acpi_get_rc_addr(struct acpi_device *adev)
+{
+	struct resource_entry *entry;
+	struct list_head list;
+	unsigned long flags;
+	int ret;
+	struct resource *res;
+
+	INIT_LIST_HEAD(&list);
+	flags = IORESOURCE_MEM;
+	ret = acpi_dev_get_resources(adev, &list,
+				     acpi_dev_filter_resource_type_cb,
+				     (void *) flags);
+	if (ret <= 0)
+		return NULL;
+
+	entry = list_first_entry(&list, struct resource_entry, node);
+	res = entry->res;
+	acpi_dev_free_resource_list(&list);
+	return res;
+}
+
+static acpi_status acpi_match_rc(acpi_handle handle, u32 lvl, void *context,
+				 void **retval)
+{
+	u16 *segment = context;
+	unsigned long long uid;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(handle, "_UID", NULL, &uid);
+	if (ACPI_FAILURE(status) || uid != *segment)
+		return AE_CTRL_DEPTH;
+
+	*(acpi_handle *)retval = handle;
+	return AE_CTRL_TERMINATE;
+}
+
+/**
+ * acpi_get_rc_resources() - get the RC address resource.
+ * @hid:	HID to search for.
+ * @segment:	PCI Segment number.
+ *
+ * Get the RC address resource that can not be described in MCFG. It takes
+ * the _HID&segment to look for and returns the RC address resource. Use
+ * _CRS of PNP0C02 devices to describe such RC address resource. Use _UID
+ * to match segment to tell which root bus the PNP0C02 resource belong to.
+ *
+ * Return: RC address resource.
+ */
+struct resource *acpi_get_rc_resources(const char *hid, u16 segment)
+{
+	struct acpi_device *adev;
+	acpi_status status;
+	acpi_handle handle;
+	int ret;
+
+	status = acpi_get_devices(hid, acpi_match_rc, &segment, &handle);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	ret = acpi_bus_get_device(handle, &adev);
+	if (ret)
+		return ret;
+
+	return acpi_get_rc_addr(adev);
+}
+#endif
+
 phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
 {
 	acpi_status status = AE_NOT_EXIST;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4518562..bf1dbfe 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -356,4 +356,8 @@  static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe)
 }
 #endif
 
+#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI)
+struct resource *acpi_get_rc_resources(const char *hid, u16 segment);
+#endif
+
 #endif /* DRIVERS_PCI_H */