Re: [PATCH 24/56] microblaze_v2: time support

Michal Simek
2008-05-06T09:56:00Z

Hi John,

> Hi Michal,
>
> On Mon, 2008-05-05 at 16:22 +0200, Michal Simek wrote:
>> Hi John,
>>
>> you wrote me you have smarter implementation that xilinx did. Can you find it
>> and send me it?
>
> It's not much (any?) better? One less multiply I think? Attached
> anyway - feel free to discard for now.
>
> We could do a nice asm implementation with the optional mulhi
> instruction, but that can wait.
>
> Cheers,
>
> John

+extern __inline__ void __udelay(unsigned int x)
{
- unsigned long long tmp = usec;
- unsigned long loops = (tmp * 4295 * HZ * loops_per_jiffy) >> 32;
+ unsigned long long tmp=(unsigned long long)x*(unsigned long
long)loops_per_jiffy*226LL;
+ unsigned loops=tmp>>32;
+
__delay(loops);
}

-#endif /* _ASM_MICROBLAZE_DELAY_H */
+extern __inline__ void __ndelay(unsigned int x)
+{
+ unsigned long long tmp=(unsigned long long)x*(unsigned long
long)loops_per_jiffy*226LL;
+ unsigned loops=tmp>>32;
+
+ __delay(loops);
+}

Why is __ndelay implementation the same with __udelay? This is weird for me.

+
+extern void __bad_udelay(void); /* deliberately undefined */
+extern void __bad_ndelay(void); /* deliberately undefined */

Are these function used anywhere?

+#define udelay(n) (__builtin_constant_p(n)? \
+ ((n) > __MAX_UDELAY? __bad_udelay(): __udelay((n) * (19 * HZ))) : \
+ __udelay((n) * (19 * HZ)))
+
+#define ndelay(n) (__builtin_constant_p(n)? \
+ ((n) > __MAX_NDELAY? __bad_ndelay(): __ndelay((n) * HZ)) : \
+ __ndelay((n) * HZ))

+#define muldiv(a, b, c) (((a)*(b))/(c))

muldiv: Where is this use?

Michal