[U-Boot-Users] U-Boot and MPC857T?

[Gunnar Larisch <la@Softing.com>]

On Wed, Jul 02, 2003 at 01:36:07PM +0200, Steven Scholz wrote:
> Hi Gunnar,
> 
> >...
> >I also thought to that, but it is not so easy, because of at least the
> >following Macros showed below.
> >
> >We have our board with a MPC855T 50 MHz and two prototypes with a MPC857T 
> >100
> >MHz. The CPU-Clock cannot be detected automatically. We need at
> >least the following differences:
> >
> >#elif defined(CONFIG_100MHz)   /* for 100 MHz  = "50 MHz" |= SCCR_EBDF01 */
> >#define CFG_SCCR       (SCCR_TBS     | SCCR_EBDF01 | \
> >                        SCCR_COM00   | SCCR_DFSYNC00 | SCCR_DFBRG00  | \
> >                        SCCR_DFNL000 | SCCR_DFNH000  | SCCR_DFLCD000 | \
> >                        SCCR_RTSEL   | SCCR_DFALCD00)
> >#define CFG_PLPRCR ( (4-1)<<PLPRCR_MF_SHIFT | PLPRCR_TEXPS | PLPRCR_TMIST )
> >#define CONFIG_8xx_GCLK_FREQ    100000000
> >#else                  /* up to 50 MHz we use a 1:1 clock (CLKOUT=GCLK2) */
> >#define CFG_SCCR       (SCCR_TBS     | \
> >                        SCCR_COM00   | SCCR_DFSYNC00 | SCCR_DFBRG00  | \
> >                        SCCR_DFNL000 | SCCR_DFNH000  | SCCR_DFLCD000 | \
> >                        SCCR_RTSEL   | SCCR_DFALCD00)
> >#define CFG_PLPRCR ( (2-1)<<PLPRCR_MF_SHIFT | PLPRCR_TEXPS | PLPRCR_TMIST )
> >#define CONFIG_8xx_GCLK_FREQ     50000000
> >#endif /* CONFIG_...MHz */
> 
> Ehm... I don't understand. The code above only depends on 
> CONFIG_100MHz and not some CONFIG_MPC855T!

Yes, I would like to have more, like this:
  Identify processor and set Clock for that processor right.

> Of course you have to compile for a specific clock frequency. But it 

I hoped not.

> shouldn't matter if it's a 855T or a 857T!

We only used a 857T instead of 855T because the 857T works with 100 MHz
internal (both with 50 MHz extern). 855T are only avaible up to 80 MHz.
Do you use another feature of the 857T?

> That's why I thought the FW (compiled for one specific clock) should 
> be able to detect the processor typ...

You are right, that is working except with the warning and our 857T
behaves the same (as slow) like a 855T.

Best regards,
Gunnar Larisch
-- 
Gunnar Larisch
Dipl.-Ing.
Development
Softing AG
Richard-Reitzner-Allee 6
85540 Haar