questions about mpc82xx_ads and porting to other, similar, platform
akostop at inaccessnetworks.com
Fri Jul 13 18:51:15 EST 2007
I am trying to port kernel 184.108.40.206 to my own platform, which incorporates
an mpc8275 chip. I'm using platform code for mpc82xx_ads as a template (is
this right in the first place?). I have a couple of questions:
1. mpc82xx_ads.c uses init_scc_ioports function to initialize the scc
uarts. However, this function is only used by the code in
arch/powerpc/sysdev/fsl_soc.c, and spefically in fs_enet_of_init(), which
is used to initialize the ethernet driver and not the cpm_uart driver.
On the other hand, cpm_uart_of_init() function seems to be the one that
initializes the uarts in cpm, and actually makes use of the device-id,
model, rx-clock and tx-clock properties of the scc nodes in OF tree. So,
AFAICT, init_scc_ioports should not be there, since it won't be actually
called at all (although I have not actually tested this - I haven't yet
managed to boot the kernel). Instead, cpm_uart_of_init should take care of
everything, except for the pport initialization, which is done in u-boot
anyway (at least in my case). Any thoughts on this?
2. I have also some questions regarding the device tree. Why are there two
nodes regarding the interrupt controller in there? and in the top level
node, what does this property means: reg = <f8200000 f8200004>; ?
Finally, in the memory node, the reg property defines a second mem region,
(f4500000 f4500020). What is this? maybe a special memory mapped
peripheral of this board? If I have a board with many mem configurations
(e.g. it uses a DIMM SDRAM what can be changed), what value should I place
in the mem node? I have to change dts every time I insert a new DIMM?
any help would be greatly appreciated,
thank you in advance
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