[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, 10 insertions, 0 deletions

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 258d74fd0b63..201ae194d1b8 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -236,6 +236,11 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 case MMLO:
                         tmp = regs->lo;
                         break;
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+                case ACX:
+                        tmp = regs->acx;
+                        break;
+#endif
                 case FPC_CSR:
                         tmp = child->thread.fpu.fcr31;
                         break;
@@ -362,6 +367,11 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 case MMLO:
                         regs->lo = data;
                         break;
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+                case ACX:
+                        regs->acx = data;
+                        break;
+#endif
                 case FPC_CSR:
                         child->thread.fpu.fcr31 = data;
                         break;