I recently ported two platforms (8245 and 8541) from ppc tree in earlier 2.6 versions into powerpc tree in 2.6.25. It is amazing how little the device tree contents are described, a lot of things required reverse engineering of the kernel code to understand the meaning of some numbers in the tree.
I am also willing to contribute into a document describing this transition, please keep me in the loop, regards, Vadim On Tue, Jun 10, 2008 at 6:19 PM, Mike Timmons <[EMAIL PROTECTED]> wrote: > Great Idea Andrew. I am no long-serving expert, but over the past few > years I've had some ARM-linux and more recently mpc5200 Linux exposure. > For the mpc5200 we started as ppc under 2.6.16 a few months ago. I > recently migrated to 2.6.24 with ARCH=powerpc. > > These were the conceptual difficulties I had at first: > > 1) Where the *%$# are the register address defines? > -Ahhh, the register definition header file maps to HW via the > device tree. Cool. Now how the $%# do I interface to the tree from my > drivers? > 3) How do I request an IRQ? > You need to create a "device" in the device tree. This is > non-intuitive because most of what you see in the tree when you start > represents actual, "devices": SOC peripherals and such. I looked and > looked for how to request > IRQ3. It was so easy when I created a, "device" and specified the > interrupt according to instructions in > Documentation/powerpc/mpc5200xx-device-tree-bindings.txt.txt > 4) How do I traverse the device tree from my code: my device drivers? > -functions like mpc52xx_find_and_map("name_from_dev_tree") are used to > map peripheral registers to the relevant defined struct from your > register definition header file. > - Also look for, "open firmware" (of) functions like > irq_of_parse_and_map(node,0). > - basically, the "find_and_map", and "parse_and_map" means your driver > is traversing the device tree data. Grep on this sort of thing to find > examples > Of how various drivers interface to the device tree info. > > This is all very simple for so many of you, but I did wrestle with some > conceptual difficulties. Andrew, if this makes any sense to you perhaps > you > Can roll it into your HOWTO. Perhaps we can collaborate offline and > publish something more useful than what I just wrote above. > > -Mike > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > On Behalf Of Andy Schmidt > Sent: Tuesday, June 10, 2008 12:49 PM > To: linuxppc-embedded@ozlabs.org > Subject: PPC to PowerPC Migration > > I am wondering if anyone has seen any good documentation for migrating > from the arch/ppc to arch/powerpc. Specifically, I am working with a > Xilinx board so I am more accustom to the xparamters.h vs. device > trees. I am very willing to build a (or multiple) tutorials to help > others in my situation, I just need some initial help getting started. > If anyone can point me in the right direction, I will be sure to keep > the group (or those interested) updated on the documentation. > > Thank you, > Andrew > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded > _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded