Convert some of the sleep.S guts to C code, which makes it easier to
use our macros and to add L2 cache handling.  We provide a helper
function, __cpu_suspend_save(), which deals with saving the common
state, setting up for resume, and flushing caches.

The remainder left as assembly code is the saving of the CPU general
purpose registers, and allocating space on the stack to save the CPU
specific registers and resume state.
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We don't require cpu_resume_turn_mmu_on as we can combine the ldr
instruction with the following code provided we ensure that
cpu_resume_mmu is aligned for older CPUs.  Note that we also align
to a 32-byte boundary to ensure that the code can't cross a section
boundary.
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Only use the preallocated page table during the resume, not while
suspending.  This avoids the overhead of having to switch unnecessarily
to the resume page table in the suspend path.
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Preallocate a page table and setup an identity mapping for the MMU
enable code.  This means we don't have to "borrow" a page table to
do this, avoiding complexities with L2 cache coherency.
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Ensure that the return value from __cpu_suspend is non-zero when
aborting.  Zero indicates a successful suspend occurred.
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

There are SoCs where attempting to enter a low power state is ignored,
and the CPU continues executing instructions with all state preserved.
It is over-complex at that point to disable the MMU just to call the
resume path.

Instead, allow the suspend finisher to return error codes to abort
suspend in this circumstance, where the cpu_suspend internals will then
unwind the saved state on the stack.  Also omit the tlb flush as no
changes to the page tables will have happened.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The first and second arguments shouldn't concern platform code, so
hide them from each platforms caller.
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

As we have core code dealing with CPU suspend/resume, we can
re-initialize the CPUs exception banked registers via that code rather
than having platforms deal with that level of detail.  So, move the
call to cpu_init() out of platform code into core code.
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

cpu_suspend() has a weird calling method which makes it only possible to
call from assembly code: it returns with a modified stack pointer to
finish the suspend, but on resume, it 'returns' via a provided pointer.

We can make cpu_suspend() appear to be a normal function merely by
swapping the resume pointer argument and the link register.

Do so, and update all callers to take account of this more traditional
behaviour.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Save the suspend function pointer onto the stack for use when returning.
Allocate r2 to pass an argument to the suspend function.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Avoid using r2 and r3 in the suspend code, allowing these to be
passed further into the function as arguments.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Make cpu_suspend()..return function preserve r4 to r11 across a suspend
cycle.  This is in preparation of relieving platform support code from
this task.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Very little code is different between these two paths now, so extract
the common code.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move the return address for cpu_resume to the top of stack so that
cpu_resume looks more like a normal function.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Eliminate the differences between MULTI_CPU and non-MULTI_CPU resume
paths, making the saved structure identical irrespective of the way
the kernel was configured.
Acked-by: NFrank Hofmann <frank.hofmann@tomtom.com>
Tested-by: NKevin Hilman <khilman@ti.com>
Acked-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: NDave Martin <dave.martin@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Allow the generic sleep code to be used with SMP CPU idle by storing
N CPU stack pointers rather than just one.  Tested on Assabet and
Tegra 2.
Tested-by: NColin Cross <ccross@android.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This adds core support for saving and restoring CPU coprocessor
registers for suspend/resume support.  This contains support for suspend
with ARM920, ARM926, SA11x0, PXA25x, PXA27x, PXA3xx, V6 and V7 CPUs.
Tested on Assabet and Tegra 2.
Tested-by: NColin Cross <ccross@android.com>
Tested-by: NKukjin Kim <kgene.kim@samsung.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>