powerpc: Make MPIC honor the "pic-no-reset" device tree property

This property, defined in the Open PIC binding, tells the kernel not to use
the reset bit in the global configuration register.  Additionally, its
presence mandates that only sources which are actually used (i.e. appear in
the device tree) should have their VECPRI bits initialized.

Although, "pic-no-reset" can be used for the same use cases that
"protected-sources" is covering, the "protected-sources" implementation was
left completely intact.  This is a more pragmatic approach as there are
already several existing systems which use protected sources.  If
"pic-no-reset" *and* "protected-sources" are both used, however, then
"pic-no-reset" takes precedence in terms of the init behavior and the
sanity checks done by protected sources will still take place.

Signed-off-by: Meador Inge <meador_inge@mentor.com>
Cc: Hollis Blanchard <hollis_blanchard@mentor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/mpic.h b/arch/powerpc/include/asm/mpic.h
index 946ec4947da2..7005ee0b074d 100644
--- a/arch/powerpc/include/asm/mpic.h
+++ b/arch/powerpc/include/asm/mpic.h
@@ -367,6 +367,10 @@ struct mpic
 #define MPIC_SINGLE_DEST_CPU            0x00001000
 /* Enable CoreInt delivery of interrupts */
 #define MPIC_ENABLE_COREINT             0x00002000
+/* Disable resetting of the MPIC.
+ * NOTE: This flag trumps MPIC_WANTS_RESET.
+ */
+#define MPIC_NO_RESET                   0x00004000
 
 /* MPIC HW modification ID */
 #define MPIC_REGSET_MASK                0xf0000000