On Tue, 2010-09-07 at 17:50 -0500, Moffett, Kyle D wrote:
On Sep 07, 2010, at 18:09, Peter Tyser wrote:
The GPIO functions above aren't hww1u1a specific. What about adding generic 85xx GPIO functions so others can use them too?
I can do that. Do you have any particular place you recommend I put them?
The 2 places that jump to mind are drivers/gpio, or arch/powerpc/cpu/mpc8xxx. My personal preference would be drivers/gpio.
Hmm, given that they all seem to inline smaller than a function call would be, I've put them as "static inline" functions in: arch/powerpc/include/asm/mpc85xx_gpio.h
Is that OK?
I'd recommend throwing it in a C file and using the "standard" gpiolib function names. That way others can easily use it to tie into U-Boot's LED, NAND, I2C, etc drivers. Eg I'd use it for LEDs immediately on a number of my company's boards if it existed. board/altera/nios2-generic/gpio.c is a simple example, arch/blackfin/cpu/gpio.c is a bit more complicated but featureful.
Is the above check the same as the hww1u1a_is_cpu_a() function previously added?
Oops, yes it is, will fix. That reminds me of one other question, though. Several variables are different between the CPU A and the CPU B on the board but maintaining 2 nearly-identical device trees is kind of a pain. Is there any good way to manage that? Should I try to poke the device tree file during boot, or is there some kind of macro language I can use in the dts file? (EG: "#ifdef CPU_A", etc)
There isn't a macro language in the dts file that you can use. Its hard to say if you should tweak the dtb in U-Boot. People's opinions vary: http://www.mail-archive.com/u-boot@lists.denx.de/msg36029.html
I'd give modifying the dtb in U-Boot a try, and people will let you know if its outside of the scope of U-Boot's responsibility.
Hmm, seems like a lot of extra work to try fiddling with the DTB for very little gain.
If done right its not much to tweak the dtb in code for what its worth.
I think at this point I'll just implement an "is_cpu_a" command and use it from a hush script something like this:
if is_cpu_a; then bootm ${flkernel} ${flinitramfs} ${fldevicetree_cpua} else bootm ${flkernel} ${flinitramfs} ${fldevicetree_cpub} fi
Does that seem OK?
Sounds good to me. You could always try adding dtb tweaking to U-Boot at a later date if you got sick of maintaining 2 device trees.
Best. Peter