Re: [PATCH 2/5] Blackfin arch: SMP supporting patchset: Blackfin header files and machine common code

Mike Frysinger
2008-11-20T13:51:00Z

On Wed, Nov 19, 2008 at 02:42, Bryan Wu wrote:
> On Wed, Nov 19, 2008 at 2:56 PM, Andrew Morton wrote:
>> On Tue, 18 Nov 2008 17:05:05 +0800 Bryan Wu wrote:
>>> From: Graf Yang <graf.yang@analog.com>
>>> +#define smp_mb__before_clear_bit() barrier()
>>> +#define smp_mb__after_clear_bit() barrier()
>>> +
>>> +static inline void __set_bit(int nr, volatile unsigned long *addr)
>>> +{
>>> + int *a = (int *)addr;
>>> + int mask;
>>> +
>>> + a += nr >> 5;
>>> + mask = 1 << (nr & 0x1f);
>>> + *a |= mask;
>>> +}
>>> +
>>> +static inline void __clear_bit(int nr, volatile unsigned long *addr)
>>> +{
>>> + int *a = (int *)addr;
>>> + int mask;
>>> +
>>> + a += nr >> 5;
>>> + mask = 1 << (nr & 0x1f);
>>> + *a &= ~mask;
>>> +}
>>> +
>>> +static inline void __change_bit(int nr, volatile unsigned long *addr)
>>> +{
>>> + int mask;
>>> + unsigned long *ADDR = (unsigned long *)addr;
>>> +
>>> + ADDR += nr >> 5;
>>> + mask = 1 << (nr & 31);
>>> + *ADDR ^= mask;
>>> +}
>>
>> I'm surprised there isn't any generic code which can be used for the above.
>>
>
> As Nick said, include/asm-generic/bitops/non-atomic.h is the generic code.
> We will try it.

the Blackfin ISA provides explicit bit operations. is there something
special about these C-level bit operations that prevents us from using
them ?

PRM:
"BITCLR" on page 13-2
"BITSET" on page 13-4
"BITTGL" on page 13-6
-mike