Re: questions about porting an 8240 arch to linux

[Wolfgang Grandegger <wolfgang.grandegger@bluewin.ch>]

Hello,

I recommend to use the linuxppc_devel_2_4 tree for your embedded board
(have a look to http://penguinppc.org/dev/kernel.shtml for further
information). The configuration and implementation for the Sandpoint
board is a good starting point as it's based on a 8240 as well. Another
good example might be the implementation for the zx4500.

Hope it helps,

Wolfgang.


On 12/05/2002 03:14 PM Abraham vd Merwe wrote:
> Hi!
>
> !!! Here's what I have:
>
> * Board based on Motorola MPC8240 processor (based on 603e core)
> * 32M sdram
> * 250mhz processor
> * board is based on PowerPC microprocessor command hardware reference
> platform (CHRP).
>
> !!! Here's what I figured out/did so far. Please correct me if I did
> something wrong.
>
> 1. used 2.4.18 w/ 2.4.18-ppc patch applied (got it from ftp.kernel.org)
> 2. added my arch to arch/ppc/config.in
> 3. added a embed_config() section to arch/ppc/boot/simple/embed_config.c for
> my arch with the following hardcoded parameters:
>
> ------------< snip <------< snip <------< snip <------------
>     bd->bi_intfreq = 250 * 1000000;
>     bd->bi_busfreq = 33 * 1000000;
>     bd->bi_memsize = 32 * 1024 * 1024;
>     bd->bi_baudrate = 9600;
> ------------< snip <------< snip <------< snip <------------
>
> i have no idea what bus bi_busfreq refers to so I assumed PCI running at
> 33mhz. what is this bus frequency?
>
> 4. add an include for my arch header in include/asm-ppc/mpc8xx.h
> 5. defined the following bd_t structure in my arch header:
>
> ------------< snip <------< snip <------< snip <------------
> typedef struct {
>     unsigned int bi_intfreq;        /* cpu frequency (hz) */
>     unsigned int bi_busfreq;        /* bus frequency (hz) */
>     unsigned int bi_memsize;        /* size of memory (bytes) */
>     unsigned int bi_baudrate;
> } bd_t;
> ------------< snip <------< snip <------< snip <------------
>
> 6. defined IMAP_ADDR, IMAP_SIZE, NR_8259_INTS in my arch header
>
> !!! things I still need to figure out or don't have a clue about:
>
> 1. what is IMAP_ADDR, IMAP_SIZE. I searched for IMMR in the MPC8240
> reference manual and couldn't find anything - I have no idea what IMAP_ADDR
> should be and I assumed IMAP_SIZE should be 64k like the other platforms.
>
> 2. what uart should I use? the user manual claims the board has a 8250
> compatible uart, but if I compile in the standard linux 16550 uart support,
> it exports the same symbols as those in arch/ppc/boot/simple/m8xx_tty.c
> which is compiled when I select M8XX support. I disabled the 16550 support
> for now and defined NR_8259_INTS to 16 (what should this be?) for now just
> to get it to compile.
>
> 3. do I need to setup any registers before branching to the kernel?
>
> --
>
> Regards
>  Abraham
>
> It's no use crying over spilt milk -- it only makes it salty for the cat.
>
> __________________________________________________________
>  Abraham vd Merwe - 2d3D, Inc.
>
>  Device Driver Development, Outsourcing, Embedded Systems
>
>   Cell: +27 82 565 4451         Snailmail:
>    Tel: +27 21 761 7549            Block C, Aintree Park
>    Fax: +27 21 761 7648            Doncaster Road
>  Email: abraham@2d3d.co.za         Kenilworth, 7700
>   Http: http://www.2d3d.com        South Africa
>
>
>


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