Re: 8270 & Watchdog - early start

Hi Matias,

On Thursday 20 September 2007 10:19, Matias Sundman wrote:

Hi,
I have a custom MPC8270 board running Linux and u-boot.
Now, I enabled the watchdog on the 8270 and need to kick it regularly by
writing ;

0x556c
0xaa39

To the internal register @ 0x0x1000e.

When I am coming out from head.S to start_kernel I was thinking of
kicking it a couple times "manually" before a timer interrupt is inserted
which will take care of it until a "superdaemon" is taking over.

I tried to serve the register as follows;

*((volatile unsigned int*)(0xf001000e))=3D0x556c;
*((volatile unsigned int*)(0xf001000e))=3D0xaa39;

But it does not take effect. I thought that since u-boot had set up the
IMMR to 0xf000'0000 I could directly write to the register as above.

Any clues why this does not work?

The Software Service Register (SWSR) is 16-bit wide. Unsigned int on the 82=
70=20
is 32-bit wide.

You must not reference physical addresses directly after the MMU has been=20
turned on. Use ioremap/iounmap to map/unmaap the CPM registers. If you're=20
using ARCH=3Dppc, you can also use the global CPM mapping cpm2_immr.

Use the out_* macros/functions to write to I/O space.

out_be16(&cpm2_immr->im_siu_conf.siu_82xx.sc_swsr, 0x556c);
out_be16(&cpm2_immr->im_siu_conf.siu_82xx.sc_swsr, 0xaa39);

Best regards,

=2D-=20
Laurent Pinchart
CSE Semaphore Belgium

Chauss=C3=A9e de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
=46 +32 (2) 387 42 75