Now that I think of it, the _multiplier_ (as I declared it here) cannot be
an integer, so this is all wrong.
I don't know how I got this working... I have a 50 Mhz oscillator with 66
Mhz system clock.
Why not use the oscillator define (CFG_8XX_XIN) for MPC866_et_al?
David
owner-linuxppc-embedded at lists.linuxppc.org wrote on 05/27/2004 03:19:26 PM:
>
> > The last if condition is wrong in this function. The change is made
> > against 0.4.8. AFAIK, 1.0.2 still has the same problem.
> >
> > And I wonder why it has to reverse engineer the oscclk when I pass the
> > value as a define to come up with the gd->cpu_clk for the MPC866
> family...
> > It is a bit useless I think.
> >
>
> Sorry, the last patch breaks on the old 8xx.
>
> This is a bit better.
>
>
> /*
> * Get timebase clock frequency (like cpu_clk in Hz)
> *
> * See table 15-5 pp. 15-16, and SCCR[RTSEL] pp. 15-27.
> */
> unsigned long get_tbclk (void)
> {
> DECLARE_GLOBAL_DATA_PTR;
>
> volatile immap_t *immr = (volatile immap_t *) CFG_IMMR;
> ulong oscclk, factor, multiplier;
>
> if (immr->im_clkrst.car_sccr & SCCR_TBS) {
> return (gd->cpu_clk / 16);
> }
> #define PLPRCR_val(a) (((CFG_PLPRCR) & PLPRCR_ ## a ## _MSK) >> PLPRCR_
##
> a ## _SHIFT)
> #ifdef CONFIG_MPC866_et_al
> /* MFN
> MFI + -------
> MFD + 1
> factor = -----------------
> (PDF + 1) * 2^S
> */
>
> factor = (PLPRCR_val(MFI) + PLPRCR_val(MFN)/(PLPRCR_val(MFD)+1));
>
> multiplier = (PLPRCR_val(MFI) +
> PLPRCR_val(MFN)/(PLPRCR_val(MFD)+1))/
> (PLPRCR_val(PDF)+1) / (1<<PLPRCR_val(S));
> #else
> multiplier = factor = PLPRCR_val(MF)+1;
> #endif
>
> oscclk = gd->cpu_clk / multiplier;
>
> if ((immr->im_clkrst.car_sccr & SCCR_RTSEL) == 0 || factor > 2) {
> return (oscclk / 4);
> }
> return (oscclk / 16);
> }
>
>
>
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