[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>

4 files changed, 24 insertions, 0 deletions

diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index c0b089d47181..222de465db73 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);
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;
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) {
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 2aa208b99da8..18f56a9dbcfa 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -229,6 +229,9 @@ void show_regs(struct pt_regs *regs)
 			printk("\n");
 	}
 
+#ifdef CONFIG_CPU_HAS_SMARTMIPS
+	printk("Acx    : %0*lx\n", field, regs->acx);
+#endif
 	printk("Hi    : %0*lx\n", field, regs->hi);
 	printk("Lo    : %0*lx\n", field, regs->lo);