[MIPS] Add basic SMARTMIPS ASE support

This patch adds trivial support for SMARTMIPS extension. This extension
is currently implemented by 4KS[CD] CPUs.

Basically it saves/restores ACX register, which is part of the SMARTMIPS
ASE, when needed. This patch does *not* add any support for Smartmips MMU
features.

Futhermore this patch does not add explicit support for 4KS[CD] CPUs since
they are respectively mips32 and mips32r2 compliant.  So with the current
processor configuration, a platform that has such CPUs needs to select
both configs:

	CPU_HAS_SMARTMIPS
	SYS_HAS_CPU_MIPS32_R[12]

This is due to the processor configuration which is mixing up all the
architecture variants and the processor types.

The drawback of this, is that we currently pass '-march=mips32' option to
gcc when building a kernel instead of '-march=4ksc' for 4KSC case. This
can lead to a kernel image a little bit bigger than required.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index c0b089d..222de46 100644
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -64,6 +64,9 @@ void output_ptreg_defines(void)
 	offset("#define PT_R31    ", struct pt_regs, regs[31]);
 	offset("#define PT_LO     ", struct pt_regs, lo);
 	offset("#define PT_HI     ", struct pt_regs, hi);
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+	offset("#define PT_ACX    ", struct pt_regs, acx);
+#endif
 	offset("#define PT_EPC    ", struct pt_regs, cp0_epc);
 	offset("#define PT_BVADDR ", struct pt_regs, cp0_badvaddr);
 	offset("#define PT_STATUS ", struct pt_regs, cp0_status);
@@ -246,6 +249,7 @@ void output_sc_defines(void)
 	text("/* Linux sigcontext offsets. */");
 	offset("#define SC_REGS       ", struct sigcontext, sc_regs);
 	offset("#define SC_FPREGS     ", struct sigcontext, sc_fpregs);
+	offset("#define SC_ACX        ", struct sigcontext, sc_acx);
 	offset("#define SC_MDHI       ", struct sigcontext, sc_mdhi);
 	offset("#define SC_MDLO       ", struct sigcontext, sc_mdlo);
 	offset("#define SC_PC         ", struct sigcontext, sc_pc);