[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Thomas Maenner]

Hi everybody,

I hope, somebody could help me with my question - and it might be a 
little bit OT.

I have TQM823L-50 modules, which have a 26bit address / 32 bit I/O 
external bus and I want to hook up external programmable logic, which 
acts as as a SRAM interface.
This is all still theoretical, so no bread board yet.

If I understand the MPC823 book correctly there already a "canned" 
memory engine available to "talk" to an SRAM.

Now:
- To which CS is that hooked up to?
- What needs to be done to the boot-loader - ppcboot|u-boot?

I would really appreciate some help there, since I am just supposed to 
setup the board for our HW guys.

Thanks

P.S. If it's too OT, then I'm sorry and please ignore

-- 
Thomas Maenner

[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Wolfgang Denk]

In message <3E4D97E5.4030708@aehr.com> you wrote:
>
> I have TQM823L-50 modules, which have a 26bit address / 32 bit I/O 
> external bus and I want to hook up external programmable logic, which 
...
> If I understand the MPC823 book correctly there already a "canned" 
> memory engine available to "talk" to an SRAM.
...
> - To which CS is that hooked up to?

That's completely your own choice.

Well, not completely. The TQM8xxL modules use:

	CS0 / CS1 for the 2 flash banks
	CS2       for SDRAM
	CS3       for the CAN controllers (if fit)

So depending if you have CAN on your modules or  not  you  can  chose
form CS4...CS7 or from CS3...CS7.

> - What needs to be done to the boot-loader - ppcboot|u-boot?

Strictly speaking, nothing. You can set up the memroy controller  for
this  CS  whenever  you  need  it,  i.  e.  for  example in the Linux
deriver's init routine. However, if you want  to  access  the  memory
under  U-Boot,  you  should  at least add appropriate definitions for
CFG_BR?_PRELIM and CFG_OR?_PRELIM to your board's config file.

> I would really appreciate some help there, since I am just supposed to 
> setup the board for our HW guys.

Good luck.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
See us @ Embedded World, Nuremberg, Feb 18-20, Hall 12.0 Booth 12-442

[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Tom Maenner]

Thanks!

On Sun, 16 Feb 2003, Wolfgang Denk wrote:

> In message <3E4D97E5.4030708@aehr.com> you wrote:
> >
> > I have TQM823L-50 modules, which have a 26bit address / 32 bit I/O
> > external bus and I want to hook up external programmable logic, which
> ...
> > If I understand the MPC823 book correctly there already a "canned"
> > memory engine available to "talk" to an SRAM.
> ...
> > - To which CS is that hooked up to?
>
> That's completely your own choice.
>
> Well, not completely. The TQM8xxL modules use:
>
> 	CS0 / CS1 for the 2 flash banks
> 	CS2       for SDRAM
> 	CS3       for the CAN controllers (if fit)
>
> So depending if you have CAN on your modules or  not  you  can  chose
> form CS4...CS7 or from CS3...CS7.
>
Well then, how does the CPU "know" about that area?
Meaning:
- Is the Address area on that bus the actual physical range the CPU sees?
- Or, does it get mapped into the CPUs physical space via configuration?
- How does the CPU know, that it is SRAM or something else?

> > - What needs to be done to the boot-loader - ppcboot|u-boot?
>
> Strictly speaking, nothing. You can set up the memroy controller  for
> this  CS  whenever  you  need  it,  i.  e.  for  example in the Linux
> deriver's init routine. However, if you want  to  access  the  memory
> under  U-Boot,  you  should  at least add appropriate definitions for
> CFG_BR?_PRELIM and CFG_OR?_PRELIM to your board's config file.
OK, I need to setup the mem controller.
(I don't need access during "boot-loader" time)
I will search in the source there.

Is that then still possible to change the mem controller setup when the
kernel is already coming up?? I hope so!
>
> > I would really appreciate some help there, since I am just supposed to
> > setup the board for our HW guys.
>
> Good luck.
Yeah, I need that :-)

Thanks for your help

Tom
>
> Best regards,
>
> Wolfgang Denk
>
> --
> Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
> Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
> See us @ Embedded World, Nuremberg, Feb 18-20, Hall 12.0 Booth 12-442
>
>
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[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Wolfgang Denk]

In message <Pine.LNX.4.44.0302171146460.7989-100000@loki.aehr.com> you wrote:
> Thanks!

You're welcome.

> > So depending if you have CAN on your modules or  not  you  can  chose
> > form CS4...CS7 or from CS3...CS7.
> >
> Well then, how does the CPU "know" about that area?

Ummm... please read the  memory  controller  section  of  the  MPC8xx
User's Manual.

> Meaning:
> - Is the Address area on that bus the actual physical range the CPU sees?

Yes.

> - Or, does it get mapped into the CPUs physical space via configuration?

Yes.

> - How does the CPU know, that it is SRAM or something else?

It doesn't know, and it doesn't need to know. It  just  goes  through
the  memory  controller registers to find a BRx/ORx pair that matches
the physical address, and  then  it  accesses  the  corresponding  CS
according to the other params in BRx/ORx.

Not that the scanning always starts at  BR0/OR0,  so  if  you  define
overlapping memory regions always the first one will win.

> OK, I need to setup the mem controller.

Right.

> I will search in the source there.

What for? Just add it to your Linux device driver's init() code.

> Is that then still possible to change the mem controller setup when the
> kernel is already coming up?? I hope so!

It is. You can change it any time you like. There are  several  cases
wher  eit  is  changed on the fly (for example, some of the FPGA boot
commands in U-Boot will mdify the memory controller  programming  for
the load operation of the FPGA(s), and return to the "normal" setting
later.

Viele Gr??e,
Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
See us @ Embedded World, Nuremberg, Feb 18-20, Hall 12.0 Booth 12-442

[U-Boot-Users] uboot newbie - tqm823 and memory conf question

[Thomas Maenner]

OK, thanks again!

Wolfgang Denk wrote:
> In message <Pine.LNX.4.44.0302171146460.7989-100000@loki.aehr.com> you wrote:
> 
>>Thanks!
> 
> 
> You're welcome.
> 
> 
>>>So depending if you have CAN on your modules or  not  you  can  chose
>>>form CS4...CS7 or from CS3...CS7.
>>>
>>
>>Well then, how does the CPU "know" about that area?
> 
> 
> Ummm... please read the  memory  controller  section  of  the  MPC8xx
> User's Manual.

Found it! Chapter 15. Digesting it...

---snip---
> 
>>- How does the CPU know, that it is SRAM or something else?
> 
> 
> It doesn't know, and it doesn't need to know. It  just  goes  through
> the  memory  controller registers to find a BRx/ORx pair that matches
> the physical address, and  then  it  accesses  the  corresponding  CS
> according to the other params in BRx/ORx.
> 
> Not that the scanning always starts at  BR0/OR0,  so  if  you  define
> overlapping memory regions always the first one will win.
> 

Good info.

---snip---
> 
>>I will search in the source there.
> 
> 
> What for? Just add it to your Linux device driver's init() code.
> 

If the "when" almost doesn't matter, it could be done there.

---snip---

Thanks a lot Wolfgang for your help!

Have a successful show in Nuremberg!

-- 
Thomas Maenner