[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, 7 insertions, 0 deletions

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index adbfb95e42d0..f091786187a6 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -89,6 +89,9 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
         for (i = 1; i < 32; i++)
                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+        err |= __put_user(regs->acx, &sc->sc_acx);
+#endif
         err |= __put_user(regs->hi, &sc->sc_mdhi);
         err |= __put_user(regs->lo, &sc->sc_mdlo);
         if (cpu_has_dsp) {
@@ -132,6 +135,10 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 
         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
+
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+        err |= __get_user(regs->acx, &sc->sc_acx);
+#endif
         err |= __get_user(regs->hi, &sc->sc_mdhi);
         err |= __get_user(regs->lo, &sc->sc_mdlo);
         if (cpu_has_dsp) {