[U-Boot] [PATCH v3 02/10] armv7: add miscellaneous utility macros

Aneesh V
2011-05-17T08:44:17Z

Hi Wolfgang,

On Tuesday 17 May 2011 10:57 AM, Wolfgang Denk wrote:
> Dear Simon Glass,
>
> In message<BANLkTine7BFSYOusgxwg0rg3owNbPN_dOQ@mail.gmail.com> you wrote:
>>
>> There are a few very primitive macros in setbits and clrbits. I would
>> very much like to see at least:
>
> Maybe we can agree to use these existing macros then instead of
> inventing new ones with the same functionality.
>
>> - define a field once in a header in an easy format along with any
>> enums which define allowable values if applicable
>> - pack and unpack a value into a field: so set a bitfield to 13, for exampl=
>> e
>> - obtain a mask for a field (i.e. with all bits set)
>> - equivalent of writel and readl for a bitfield (writel in fact being
>> read/modify/write so perhaps a different name)
>>
>> Some of these exist, some don't.
>
> Do you know of examples of such more complex definitions in the Linux
> kernel code?
>

In fact I had searched for a macro for similar needs as my
set_bit_field() is addressing in Linux Kernel too but didn't find any.

Please note that my requirement is not for doing IO but doing bit field
operations on a C integer variable:
1. Prepare a variable field by field to be finally written to a
register using writel()
2. Extract a field from a variable that typically holds the value of a
register after a readl()

I couldn't find any utility macros/functions for doing something like
this.

Please somebody correct me if I am wrong.

best regards,
Aneesh