This is a UIC cascade handler rework to use set_irq_chained_handler() for
cascade, just like othe ppc platforms do. With current implementation we have
additional redirection for irq handler and we call generic_handle_irq twice
(once for the primary uic and the other time for handling cascade interrupt).
This causes Ingo's realtime support patch to stop working on 4xx.

Not sure of any other possible problems though, but with
set_irq_chained_handler() we can abolish "struct irqaction cascade" from the
chip descriptor and call generic_handle_irq() once, directly for cascade irq.
Signed-off-by: NValentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

This patch makes PowerPC 4xx UIC use generic level irq handler instead
of a custom handle_uic_irq() function. We ack only edge irqs in mask_ack
callback, since acking a level irq on UIC has no effect if the interrupt
is still asserted by the device, even if the interrupt is already masked.
So, to really de-assert the interrupt we need to de-assert the external
source first *and* ack it on UIC then. The handle_level_irq() function
masks and ack's the interrupt with mask_ack callback prior to calling
the actual ISR and unmasks it at the end. So, to use it with UIC interrupts
we need to ack level irqs in the unmask callback instead, after the ISR
has de-asserted the external interrupt source. Even if we ack the interrupt
that we didn't handle (unmask/ack it at the end of the handler, while
next irq is already pending) it will not de-assert the irq, untill we
de-assert its exteral source.
Signed-off-by: NValentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

This adds uic_mask_ack_irq() callback to PowerPC 4xx uic code
to avoid kernel crash. It is used for edge-triggered interrupts
by handle_uic_irq().
Signed-off-by: NValentine Barshak <vbarshak@ru.mvista.com>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

The most common match semantic is an exact match based on the device node.
So provide a default implementation that does this, and hook it up if no
match routine is specified.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The majority of irq_host implementations (3 out of 4) are associated
with a device_node, and need to stash it somewhere. Rather than having
it somewhere different for each host, add an optional device_node pointer
to the irq_host structure.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

At present the cascade interrupt handler for the UIC (interrupt
controller on 4xx embedded chips) will misbehave badly if it is called
spuriously - that is if the handler is invoked when no interrupts are
asserted in the child UIC.

Although spurious interrupts shouldn't happen, it's good to behave
robustly if they do.  This patch does so by checking for and ignoring
spurious interrupts.
Signed-off-by: NValentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Acked-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

At present the driver for the UIC (the embedded interrupt controller
in 4xx chips) uses the handle_level_irq() flow handler.  It turns out
this does not correctly handle level triggered interrupts on the UIC.

Specifically, acknowledging an irq on the UIC (i.e. clearing the
relevant bit in UIC_SR) will have no effect for a level interrupt
which is still asserted by the external device, even if the irq is
already masked.  Therefore, unlike handle_level_irq() we must ack the
interrupt after invoking the ISR (which should cause the device to
stop asserting the irq) instead of acking it when we mask it, before
the ISR.

This patch implements this change, in a new handle_uic_irq(), a
customised irq flow handler for the UIC.  For edge triggered
interrupts, handle_uic_irq() still uses the old flow - we must ack
edge triggered interrupt before the ISR not after, or we could miss a
second event which occurred between invoking the ISR and acking the
irq.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Acked-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The UIC (interrupt controller in 4xx embedded CPUs) driver currently
missets the IRQ_lEVEL flag in desc->status, due to a thinko.  This
patch fixes the bug.

Currently this is only a cosmetic problem (affects the output in
/proc/interrupts), however subsequent patches will use the IRQ_LEVEL
flag to affect flow handling.
Signed-off-by: NValentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Acked-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

for consistency with other Open Firmware interfaces (and Sparc).

This is just a straight replacement.

This leaves the compatibility define in place.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Just another pass through arch/powerpc for old usages.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch adds a driver to arch/powerpc/sysdev for the UIC, the
on-chip interrupt controller from IBM/AMCC 4xx chips.  It uses the new
irq host mapping infrastructure.
Signed-off-by: NDavid Gibson <dwg@au1.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>