xtensa: replace variant/core.h with asm/core.h

Introduce the header arch/xtensa/include/asm/core.h that provides
definitions for XCHAL macros missing in older xtensa releases. Use this
header instead of variant/core.h

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: drop variant IRQ support

If an xtensa core provides an additional IRQ controller it should be
treated as a separate piece of hardware and be driven by an irqchip
driver.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: move PLATFORM_NR_IRQS to Kconfig

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: don't use linux IRQ #0

Linux IRQ #0 is reserved for error reporting and may not be used.
Increase NR_IRQS for one additional slot and increase
irq_domain_add_legacy parameter first_irq value to 1, so that linux
IRQ #0 is not associated with hardware IRQ #0 in legacy IRQ domains.
Introduce macro XTENSA_PIC_LINUX_IRQ for static translation of xtensa
PIC hardware IRQ # to linux IRQ #. Use this macro in XTFPGA platform
data definitions.

This fixes inability to use hardware IRQ #0 in configurations that don't
use device tree and allows for non-identity mapping between linux IRQ #
and hardware IRQ #.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: implement CPU hotplug

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

xtensa: add MX irqchip

MX is an interrupt distributor used in some SMP-capable xtensa
configurations.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

xtensa: move built-in PIC to drivers/irqchip

Extract xtensa built-in interrupt controller implementation from
xtensa/kernel/irq.c and move it to other irqchips, providing way to
instantiate it from the device tree.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

xtensa: allow variant to initialize own irq chips

There was already a PLATFORM_NR_IRQS define, which is now accompanied
by a VARIANT_NR_IRQS. To be able to initialize these interrupts,
init_IRQ now calls a variant specific hook.

Changes compared to v1:
- adapted to new CONFIG_VARIANT_IRQ_EXT
- removed definition and call of platform_init_IRQ as there already
is a platform_init_irq defined in asm/platform.h with a weak default
in kernel/platform.c
- renamed variant_init_IRQ to variant_init_irq

Note that I could not find the call site of platform_init_irq although
it is stated in platform.h that it is called from init_IRQ.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

xtensa: variant irq set callbacks

Allow the core variant code to provide irq enable/disable callbacks.

Signed-off-by: Johannes Weiner <jw@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

xtensa: move headers files to arch/xtensa/include

Move all header files for xtensa to arch/xtensa/include and platform and
variant header files to the appropriate arch/xtensa/platforms/ and
arch/xtensa/variants/ directories.

Moving the files gets also rid of all uses of symlinks in the Makefile.

This has been completed already for the majority of the architectures
and xtensa is one out of six missing.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Chris Zankel <chris@zankel.net>