This commit changes the PMSU driver to no longer map itself the CPU
reset registers, and instead call into the CPU reset driver to
deassert the secondary CPUs for SMP booting.
In order to provide Device Tree backward compatibility, the CPU reset
driver is extended to not only support its official compatible string
"marvell,armada-370-cpu-reset", but to also look at the PMSU
compatible string "marvell,armada-370-xp-pmsu" to find the CPU reset
registers address. This allows old Device Tree to work correctly with
newer kernel versions. Therefore, the CPU reset driver implements the
following logic:
* If one of the normal compatible strings
"marvell,armada-370-cpu-reset" is found, then we map its first
memory resource as the CPU reset registers.
* Otherwise, if none of the normal compatible strings have been
found, we look for the "marvell,armada-370-xp-pmsu" compatible
string, and we map the second memory as the CPU reset registers.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-3-git-send-email-thomas.petazzoni@free-electrons.com
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
The Armada 370 and Armada XP have registers that allow to reset the
CPUs, which is particularly useful to take the secondary CPUs out of
reset in the context of the SMP support.
Unfortunately, an implementation mistake was originally made and the
support for these registers was integrated into the PMSU driver, which
is in fact completely unrelated. And it turns out that the Armada 375
has the same CPU reset registers, but does not have the PMSU
registers.
Therefore, this commit creates a small CPU reset driver. All it does
is provide a simple mvebu_cpu_reset_deassert() function that the SMP
support code can call to take secondary CPUs out of reset. As of this
commit, the driver isn't being used, it will be used through changes
in the following commits.
Note that we initially planned to use the 'reset controller'
framework, but it requires the addition of "resets" properties in the
Device Tree, which are causing too many problems if we want to keep
the Device Tree backward compatibility. Moreover, the 'reset
controller' framework is mainly useful when a device driver needs to
request a reset of its device from a separate reset controller. In our
case, the CPU reset handling and the SMP core code are both located in
arch/arm/mach-mvebu/ and are tightly linked together, so there's no
real benefit in going through a separate framework.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-2-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
