On 9/19/06, David H. Lynch Jr. <[EMAIL PROTECTED]> wrote: > > Grant Likely wrote: > > Avast! After getting quizzed on IRC about this off-the-cuff comment, > I should probably clarify. Since the Xilinx IP could be wired up to a > ublaze core or an off-chip processor, the drivers still need to use a > platform bus attachment to keep it all cross platform. > > So, replace above comment with the following: > > Populating the platform device with static code during initialization > is sooo last year. > > Time to hack device trees to populate it instead. > > So I got another X V4 board. I hacked in the Platform device stuff from > you ml403 code with changes needed for my hardware. > and my brain is slowly begining to actually grasp what is going on - I > am begining to grasp the platform devices big picture (over a mountain > through a spyglass in the fog) > > Where do I begin with Device Trees ?
Step 1: run away Step 2: don't look back. Just kidding. Unless you want to help move Virtex support from arch/ppc to arch/powerpc, you don't really need to worry about device trees for a while. If you are interested, look at Documentation/powerpc/booting-without-of.txt. Then start poking Matt Porter about when he's going to get 4xx ported to arch/powerpc. I've been half heartedly looking at what needs to be done to generate a device tree based on either system.mhs or xparameters.h. I'm probably going to write a tiny C program that is compiled against xparameters.h and spits out a valid dts file. The dts file can then be run through the device tree compiler to produce the flattened device tree structure. > > The vague Picture I have is the have something to do with some > datastructure that Mac's typically create at or prior to boot. And that for > embedded systems we are building them > externally compiling them and then attaching the compiled device tree > to our project. That right. You don't compile device base addresses, irqs, etc into the kernel. You pass them in at boot time with a data structure. > > I got a Xilinv V4 device currently with a Pic, UartLite, TEMAC, Flash > and Keyhole (pseuodo serial host interface). Of those it is only certain > that the flash will always be there. > We have bit images with Keyhole only, Uartlite only TEMAC only, > Sometimes we have a Pic sometimes not. I was trying to get to the point were > I could dynamically add what was there > to Platform devices during initialization. > > If Device trees are static, then do they even apply to what I have to > deal with ? Device trees don't have to be static. They can be generated/modified on the fly if the bootloader supports it. Or you can pass a different tree depending on what IP you have on the board. Cheers, g. -- Grant Likely, B.Sc. P.Eng. Secret Lab Technologies Ltd. [EMAIL PROTECTED] (403) 399-0195 _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
