[U-Boot-Users] serial: polling or interrupt based?

Benjamin Collar benjamin.collar at siemens.com
Fri Sep 24 13:54:49 CEST 2004


Hi folks

I'm trying to set up the serial interface on my happy little board.
Reading the CPU's manual (CPU is mpc852T), I'm at this section called
SCC Initialization. I'm a bit confused, because the initialization
procedure specifically says:

...
10. Write ones to SCCM register to enable interrupts
11. Write CICR to configure the SCC interrupt priority
12. Clear out any interrupts in CIPR
13. Write the CIMR to enable interrupts to the CPIC.
...

However, the u-boot code writes zeros to the SCCM and doesn't touch
CIMR. So I guess it's polling based, yes?

Then the question is, do I simply skip steps 10-13? If I wanted to use
interrupts instead of polling, what else would I need to change?

On a similar note, the manual for the MPC866, in appendix H which is
specific for MPC852T, specifies that there is no BRG1 nor BRG2. The
u-boot hard codes wiring BRG1 to the selected SCC. Why? Even more
important: I have to obviously change it; is there more than one place I
need to change (namely, replace cp_brgc1 with cp_brgc4)?

Thanks 
Ben

-- 
Benjamin Collar
Siemens AG
CT SE 2
Embedded Linux
089-636-53711






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