sh: add support for J-Core J2 processor

At the CPU/ISA level, the J2 is compatible with SH-2, and thus the
changes to add J2 support build on existing SH-2 support. However, J2
does not duplicate the memory-mapped SH-2 features like the cache
interface. Instead, the cache interfaces is described in the device
tree, and new code is added to be able to access the flat device tree
at early boot before it is unflattened.

Support is also added for receiving interrupts on trap numbers in the
range 16 to 31, since the J-Core aic1 interrupt controller generates
these traps. This range was unused but nominally for hardware
exceptions on SH-2, and a few values in this range were used for
exceptions on SH-2A, but SH-2A has its own version of the relevant
code.

No individual cpu subtypes are added for J2 since the intent moving
forward is to represent SoCs with device tree rather than as
hard-coded subtypes in the kernel. The CPU_SUBTYPE_J2 Kconfig item
exists only to fit into the existing cpu selection mechanism until it
is overhauled.

Signed-off-by: Rich Felker <dalias@libc.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index df6339d7bf72..2ef6f652bc50 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -186,6 +186,12 @@ config CPU_SH2A
 	select CPU_SH2
 	select UNCACHED_MAPPING
 
+config CPU_J2
+	bool
+	select CPU_SH2
+	select OF
+	select OF_EARLY_FLATTREE
+
 config CPU_SH3
 	bool
 	select CPU_HAS_INTEVT
@@ -252,6 +258,10 @@ config CPU_SUBTYPE_SH7619
 	select CPU_SH2
 	select SYS_SUPPORTS_SH_CMT
 
+config CPU_SUBTYPE_J2
+	bool "Support J2 processor"
+	select CPU_J2
+
 # SH-2A Processor Support
 
 config CPU_SUBTYPE_SH7201