irqchip/mips: Fix RCU violation when using irqdomain lookup on interrupt entry

Since d4a45c68dc81 ("irqdomain: Protect the linear revmap with RCU"),
any irqdomain lookup requires the RCU read lock to be held.

This assumes that the architecture code will be structured such as
irq_enter() will be called *before* the interrupt is looked up
in the irq domain. However, this isn't the case for MIPS, and a number
of drivers are structured to do it the other way around when handling
an interrupt in their root irqchip (secondary irqchips are OK by
construction).

This results in a RCU splat on a lockdep-enabled kernel when the kernel
takes an interrupt from idle, as reported by Guenter Roeck.

Note that this could have fired previously if any driver had used
tree-based irqdomain, which always had the RCU requirement.

To solve this, provide a MIPS-specific helper (do_domain_IRQ())
as the pendent of do_IRQ() that will do thing in the right order
(and maybe save some cycles in the process).

Ideally, MIPS would be moved over to using handle_domain_irq(),
but that's much more ambitious.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
[maz: add dependency on CONFIG_IRQ_DOMAIN after report from the kernelci bot]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20210705172352.GA56304@roeck-us.net
Link: https://lore.kernel.org/r/20210706110647.3979002-1-maz@kernel.org

irqchip/mips-cpu: Set IPI domain parent chip

Since commit 55567976629e ("genirq/irqdomain: Allow partial trimming of
irq_data hierarchy") the irq_data chain is valided.

The irq_domain_trim_hierarchy() function doesn't consider the irq + ipi
domain hierarchy as valid, since the ipi domain has the irq domain set
as parent, but the parent domain has no chip set. Hence the boot ends in
a kernel panic.

Set the chip for the parent domain as it is done in the mips gic irq
driver, to have a valid irq_data chain.

Fixes: 3838a547fda2 ("irqchip: mips-cpu: Introduce IPI IRQ domain support")
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Mathias Kresin <dev@kresin.me>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210107213603.1637781-1-dev@kresin.me

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MIPS: Unify checks for sibling CPUs

Up until now we have open-coded checks for whether CPUs are siblings,
with slight variations on whether we consider the package ID or not.

This will only get more complex when we introduce cluster support, so in
preparation for that this patch introduces a cpus_are_siblings()
function which can be used to check whether or not 2 CPUs are siblings
in a consistent manner.

By checking globalnumber with the VP ID masked out this also has the
neat side effect of being ready for multi-cluster systems already.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17011/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

irqchip/mips-cpu: Drop unnecessary static

Drop static on a local variable, when the variable is initialized before
any possible use. Thus, the static has no benefit.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@bad exists@
position p;
identifier x;
type T;
@@
static T x@p;
...
x = <+...x...+>

@@
identifier x;
expression e;
type T;
position p != bad.p;
@@
-static
T x@p;
... when != x
when strict
?x = e;
// </smpl>


Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kernel-janitors@vger.kernel.org
Cc: keescook@chromium.org
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1500149266-32357-7-git-send-email-Julia.Lawall@lip6.fr

irqchip/MSI: Use irq_domain_update_bus_token instead of an open coded access

Now that we have irq_domain_update_bus_token(), switch everyone over
to it. The debugfs code thanks you for your continued support.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

irqchip: mips-cpu: Introduce IPI IRQ domain support

Introduce support for registering an IPI IRQ domain suitable for use by
systems using the MIPS MT (multithreading) ASE within a single core.
This will allow for such systems to be supported generically, without
the current kludge of IPI code split between the MIPS arch & the malta
board support code.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15836/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

irqchip: mips-cpu: Prepare for non-legacy IRQ domains

The various struct irq_chip callbacks in the MIPS CPU interrupt
controller driver have been calculating the hardware interrupt number by
subtracting MIPS_CPU_IRQ_BASE from the virq number. This presumes a
linear mapping beginning from MIPS_CPU_IRQ_BASE, and this will not hold
once an IPI IRQ domain is introduced. Switch to using the hwirq field of
struct irq_data which already contains the hardware interrupt number
instead of attempting to calculate it.

Similarly, plat_irq_dispatch calculated the virq number by adding
MIPS_CPU_IRQ_BASE to the hardware interrupt number. Ready this for the
introduction of an IPI IRQ domain by instead using irq_linear_revmap.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15835/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

irqchip: mips-cpu: Replace magic 0x100 with IE_SW0

Replace use of the magic number 0x100 (ie. bit 8) with the more
explanatory IE_SW0 (ie. interrupt enable for software interrupt 0) or
C_SW0 (ie. cause bit for software interrupt 0) as appropriate.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15834/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

irqchip: Prepare for local stub header removal

The IRQCHIP_DECLARE macro moved to to 'include/linux/irqchip.h', so
the local irqchip.h became an empty shell, which solely includes
include/linux/irqchip.h

Include the global header in all irqchip drivers instead of the local
header, so we can remove it.

Signed-off-by: Joel Porquet <joel@porquet.org>
Cc: vgupta@synopsys.com
Cc: monstr@monstr.eu
Cc: ralf@linux-mips.org
Cc: jason@lakedaemon.net
Link: http://lkml.kernel.org/r/1882096.X39jVG8e0D@joel-zenbook
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

IRQCHIP: irq_cpu: declare irqchip table entry

Allow the MIPS CPU interrupt controller to be probed from DT using the
generic __irqchip_of_table for platforms which use irqchip_init. This
will avoid such platforms needing to duplicate the compatible string &
init function pointer.

[ralf@linux-mips.org: Resolved conflict due the preceeding commit that
moves irq-cpu.c.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-mips@linux-mips.org
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: linux-kernel@vger.kernel.org
Cc: Felix Fietkau <nbd@openwrt.org>
Patchwork: https://patchwork.linux-mips.org/patch/10131/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS/IRQCHIP: Move irq_chip from arch/mips to drivers/irqchip.

While at it, rename it because in drivers/irqchip no longer every CPU is
a MIPS.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>