[PATCH 2/2] coresight: Adding coresight support to arm64

On 2 February 2015 at 06:45, Will Deacon [off-list ref] wrote:

On Fri, Jan 30, 2015 at 10:54:26PM +0000, mathieu.poirier at linaro.org wrote:

quoted

From: Mathieu Poirier <mathieu.poirier@linaro.org>

Aside from tracers, all currently supported coresight IP blocks
are 64 bit ready.  As such add the required symbol definition to
compile the framework and drivers.

Also fixing a couple of warnings picked up by the 64bit compiler.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 arch/arm64/Kconfig.debug            | 48 +++++++++++++++++++++++++++++++++++++
 drivers/coresight/coresight-etb10.c |  2 +-
 drivers/coresight/coresight-tmc.c   |  2 +-
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 5fdd6dce8061..77dfebbcbffe 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug

@@ -66,4 +66,52 @@ config DEBUG_SET_MODULE_RONX
           against certain classes of kernel exploits.
           If in doubt, say "N".

+menuconfig CORESIGHT
+     bool "CoreSight Tracing Support"
+     select ARM_AMBA
+     help
+       This framework provides a kernel interface for the CoreSight debug
+       and trace drivers to register themselves with. It's intended to build
+       a topological view of the CoreSight components based on a DT
+       specification and configure the right serie of components when a
+       trace source gets enabled.

Why does this need to be duplicated by each architecture wanting to make
use of coresight capabilities defined under drivers/coresight? Can't we
instead have this menuconfig and associated suboptions defined by a core
Kconfig file, then have HAVE_ARCH_CORESIGHT_TRACE or something which can
be selected by architectures wanting to make use of the framework?

Will

"arch/arm/Kconfig.debug" and "arch/arm64/Kconfig.debug" already have a
fair amount of duplication so I wasn't sure if this is the approach
you guys wanted to take.  I agree that a common core Kconfig file
would make much more sense and I see a couple of ways to do this:

1) lib/Kconfig.debug being sourced by both arm/Kconfig.debug and
arm64/Kconfig.debug.  We can add a lib/Kconfig.coresight or
lib/Kconfig.arm and source them the same way.

2) Adding coresight entries to the Kconfig.debug made sense a while
back.  Maybe it is time to move them to drivers/coresight/Kconfig...
That way it would be easily accessible by both arm and arm64.

You may have ideas of your own too...

Thanks,
Mathieu