diff mbox

[v2,1/3] ACPI : introduce macros for using the ACPI specification version

Message ID 1434666968-1543-2-git-send-email-al.stone@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

al.stone@linaro.org June 18, 2015, 10:36 p.m. UTC
Add the ACPI_SPEC_VERSION() macro to build a proper version number from
a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
that constructs a proper version number from the entries in the current
FADT.

These macros are added in order to simplify retrieving and comparing ACPI
specification version numbers, since this is becoming a more frequent need.
In particular, there are some architectures that require at least a certain
version of the spec, and there are differences in some structure sizes that
have changed with recent versions but can only be tracked by spec version
number.

Signed-off-by: Al Stone <al.stone@linaro.org>
---
 include/linux/acpi.h | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Hanjun Guo June 19, 2015, 10:49 a.m. UTC | #1
On 06/19/2015 06:36 AM, Al Stone wrote:
> Add the ACPI_SPEC_VERSION() macro to build a proper version number from
> a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
> that constructs a proper version number from the entries in the current
> FADT.
>
> These macros are added in order to simplify retrieving and comparing ACPI
> specification version numbers, since this is becoming a more frequent need.
> In particular, there are some architectures that require at least a certain
> version of the spec, and there are differences in some structure sizes that
> have changed with recent versions but can only be tracked by spec version
> number.
>
> Signed-off-by: Al Stone <al.stone@linaro.org>
> ---
>   include/linux/acpi.h | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index a4acb55..33ed313 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -48,6 +48,11 @@
>   #include <acpi/acpi_io.h>
>   #include <asm/acpi.h>
>
> +#define ACPI_SPEC_VERSION(major, minor)	((major<<8)|minor)

and minor comments for code style

((major<<8)|minor) - > ((major << 8) | minor)

other than that:

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun

> +#define ACPI_FADT_SPEC_VERSION	\
> +	ACPI_SPEC_VERSION(acpi_gbl_FADT.header.revision, \
> +			  acpi_gbl_FADT.minor_revision)
> +
>   static inline acpi_handle acpi_device_handle(struct acpi_device *adev)
>   {
>   	return adev ? adev->handle : NULL;
>
Al Stone June 19, 2015, 8:01 p.m. UTC | #2
On 06/19/2015 04:49 AM, Hanjun Guo wrote:
> On 06/19/2015 06:36 AM, Al Stone wrote:
>> Add the ACPI_SPEC_VERSION() macro to build a proper version number from
>> a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
>> that constructs a proper version number from the entries in the current
>> FADT.
>>
>> These macros are added in order to simplify retrieving and comparing ACPI
>> specification version numbers, since this is becoming a more frequent need.
>> In particular, there are some architectures that require at least a certain
>> version of the spec, and there are differences in some structure sizes that
>> have changed with recent versions but can only be tracked by spec version
>> number.
>>
>> Signed-off-by: Al Stone <al.stone@linaro.org>
>> ---
>>   include/linux/acpi.h | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index a4acb55..33ed313 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -48,6 +48,11 @@
>>   #include <acpi/acpi_io.h>
>>   #include <asm/acpi.h>
>>
>> +#define ACPI_SPEC_VERSION(major, minor)    ((major<<8)|minor)
> 
> and minor comments for code style
> 
> ((major<<8)|minor) - > ((major << 8) | minor)

Ah.  Yeah, good idea.  I can roll that into next version.

> other than that:
> 
> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks.

> Thanks
> Hanjun
> 
>> +#define ACPI_FADT_SPEC_VERSION    \
>> +    ACPI_SPEC_VERSION(acpi_gbl_FADT.header.revision, \
>> +              acpi_gbl_FADT.minor_revision)
>> +
>>   static inline acpi_handle acpi_device_handle(struct acpi_device *adev)
>>   {
>>       return adev ? adev->handle : NULL;
>>
> -- 
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
Rafael J. Wysocki June 30, 2015, 8:12 p.m. UTC | #3
Hi Al,

On Fri, Jun 19, 2015 at 12:36 AM, Al Stone <al.stone@linaro.org> wrote:
> Add the ACPI_SPEC_VERSION() macro to build a proper version number from
> a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
> that constructs a proper version number from the entries in the current
> FADT.
>
> These macros are added in order to simplify retrieving and comparing ACPI
> specification version numbers, since this is becoming a more frequent need.
> In particular, there are some architectures that require at least a certain
> version of the spec, and there are differences in some structure sizes that
> have changed with recent versions but can only be tracked by spec version
> number.
>
> Signed-off-by: Al Stone <al.stone@linaro.org>
> ---
>  include/linux/acpi.h | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index a4acb55..33ed313 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -48,6 +48,11 @@
>  #include <acpi/acpi_io.h>
>  #include <asm/acpi.h>
>
> +#define ACPI_SPEC_VERSION(major, minor)        ((major<<8)|minor)

One nit here.

acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it
by 8 bit positions only works due to some implicit type casting I
suppose.

Moreover, it is not entirely clear why the macro is specific to the
computation of the ACPI spec version.

So I'd drop ACPI_SPEC_VERSION and only define ACPI_FADT_SPEC_VERSION
as something like

#define ACPI_FADT_SPEC_VERSION (((unsigned
int)acpi_gbl_FADT.header.revision << 8) | (unsigned
int)acpi_gbl_FADT.minor_revision)

Thanks,
Rafael
al.stone@linaro.org June 30, 2015, 9:15 p.m. UTC | #4
On 06/30/2015 02:12 PM, Rafael J. Wysocki wrote:
> Hi Al,
> 
> On Fri, Jun 19, 2015 at 12:36 AM, Al Stone <al.stone@linaro.org> wrote:
>> Add the ACPI_SPEC_VERSION() macro to build a proper version number from
>> a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
>> that constructs a proper version number from the entries in the current
>> FADT.
>>
>> These macros are added in order to simplify retrieving and comparing ACPI
>> specification version numbers, since this is becoming a more frequent need.
>> In particular, there are some architectures that require at least a certain
>> version of the spec, and there are differences in some structure sizes that
>> have changed with recent versions but can only be tracked by spec version
>> number.
>>
>> Signed-off-by: Al Stone <al.stone@linaro.org>
>> ---
>>  include/linux/acpi.h | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index a4acb55..33ed313 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -48,6 +48,11 @@
>>  #include <acpi/acpi_io.h>
>>  #include <asm/acpi.h>
>>
>> +#define ACPI_SPEC_VERSION(major, minor)        ((major<<8)|minor)
> 
> One nit here.
> 
> acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it
> by 8 bit positions only works due to some implicit type casting I
> suppose.

Bah.  That was being sloppy on my part.  Sorry about that.  Will fix.

> Moreover, it is not entirely clear why the macro is specific to the
> computation of the ACPI spec version.

As far as I know, that's the only way to extract the spec version from
tables; I don't recall there being any other table with that info.  Since
I will likely use this again, it seemed to make sense at the time.

> So I'd drop ACPI_SPEC_VERSION and only define ACPI_FADT_SPEC_VERSION
> as something like
> 
> #define ACPI_FADT_SPEC_VERSION (((unsigned
> int)acpi_gbl_FADT.header.revision << 8) | (unsigned
> int)acpi_gbl_FADT.minor_revision)
> 
> Thanks,
> Rafael
> 

Sure.  That makes sense.  It makes it clearer that this is the version
just from the FADT.  I'll do that.
Hanjun Guo July 1, 2015, 2:30 a.m. UTC | #5
On 2015/7/1 5:15, Al Stone wrote:
> On 06/30/2015 02:12 PM, Rafael J. Wysocki wrote:
>> Hi Al,
>>
>> On Fri, Jun 19, 2015 at 12:36 AM, Al Stone <al.stone@linaro.org> wrote:
>>> Add the ACPI_SPEC_VERSION() macro to build a proper version number from
>>> a major and minor revision number.  Add also the ACPI_FADT_SPEC_VERSION
>>> that constructs a proper version number from the entries in the current
>>> FADT.
>>>
>>> These macros are added in order to simplify retrieving and comparing ACPI
>>> specification version numbers, since this is becoming a more frequent need.
>>> In particular, there are some architectures that require at least a certain
>>> version of the spec, and there are differences in some structure sizes that
>>> have changed with recent versions but can only be tracked by spec version
>>> number.
>>>
>>> Signed-off-by: Al Stone <al.stone@linaro.org>
>>> ---
>>>  include/linux/acpi.h | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>>> index a4acb55..33ed313 100644
>>> --- a/include/linux/acpi.h
>>> +++ b/include/linux/acpi.h
>>> @@ -48,6 +48,11 @@
>>>  #include <acpi/acpi_io.h>
>>>  #include <asm/acpi.h>
>>>
>>> +#define ACPI_SPEC_VERSION(major, minor)        ((major<<8)|minor)
>> One nit here.
>>
>> acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it
>> by 8 bit positions only works due to some implicit type casting I
>> suppose.
> Bah.  That was being sloppy on my part.  Sorry about that.  Will fix.
>
>> Moreover, it is not entirely clear why the macro is specific to the
>> computation of the ACPI spec version.
> As far as I know, that's the only way to extract the spec version from
> tables; I don't recall there being any other table with that info.  Since
> I will likely use this again, it seemed to make sense at the time.

That's true from ACPI 5.1, as we discussed in ACPI spec working group,
FADT Major Version and FADT Minor Version are recognized as ACPI Major/Minor
version. yes, the spec itself didn't state that explicitly, maybe a ECR
to make it explicit will be good, I can prepare one if that makes sense.

Thanks
Hanjun
diff mbox

Patch

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index a4acb55..33ed313 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -48,6 +48,11 @@ 
 #include <acpi/acpi_io.h>
 #include <asm/acpi.h>
 
+#define ACPI_SPEC_VERSION(major, minor)	((major<<8)|minor)
+#define ACPI_FADT_SPEC_VERSION	\
+	ACPI_SPEC_VERSION(acpi_gbl_FADT.header.revision, \
+			  acpi_gbl_FADT.minor_revision)
+
 static inline acpi_handle acpi_device_handle(struct acpi_device *adev)
 {
 	return adev ? adev->handle : NULL;