Exactly, I mean ppc_md.init_IRQ().
Ok. What have I to setup in this function ? I set the mask and other registers. Is it right ? How do I chose the mask ?
At the end of this funtion, IRQ are disable. Is that right ? So who does enable IRQs ?
Sorry for all this questions, I am learning the low layer of Linux.
2008/8/21, Michael Ellerman <michael@ellerman.id.au>:
On Thu, 2008-08-21 at 09:13 +0200, Sébastien Chrétien wrote:
> Hello,
>
> What are the constraints in order to implement a irq_init function ?
You mean ppc_md.init_IRQ() ?
If so, it's a hook you can use to setup your interrupt controller. It's
called from init_IRQ() (arch/powerpc/kernel/irq.c), which is called from
start_kernel() (init/main.c).
Not long after it is called irqs are enabled. I think it is the last
callback into arch code before irqs are enabled.
When it is called the device tree is unflattened, so you can use the of_
API. Bootmem is setup so you can use alloc_bootmem(), but you can't
kmalloc yet. ioremap should work.
> What is the aim or get_irq ? Does it retun an information about the
> mask, the states, or... ?
The aim of ppc_md.get_irq() ? It's called from do_IRQ()
(arch/powerpc/kernel/irq.c) which is called from assembler in the
appropriate head_x.S
It just returns the number (virtual number) of the irq that just fired.
If for some reason you took a spurious interrupt it should return
NO_IRQ.
I'm not sure what you mean about masks or states, someone else might
though.
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person