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authorPaul Mundt <lethal@linux-sh.org>2009-08-15 07:43:21 +0900
committerPaul Mundt <lethal@linux-sh.org>2009-08-15 07:43:21 +0900
commit7dd6662a92fe9a15ad565045aa60367995cc533d (patch)
tree980dfdc46083e005380e545ec400089841bb0a92
parent7a90e00dda0bae66b5232d5a37155f13a0581369 (diff)
sh: delay slot future proofing via EXPMASK on SH-4A parts.
This implements EXPMASK initialization code for SH-4A parts, where it is possible to disable compat features that will go away in newer cores. Presently this includes disabling support for non-nop instructions in the rte delay slot, as well as a sleep instruction being placed in a delay slot (neither of which the kernel does any longer). As a result of this, any future offenders will have illegal slot exceptions generated for them. Associative writes for the memory-mapped cache array are still left enabled, until such a point that special cache operations for SH-4A are provided to move off of the current (and rather dated) SH-4 versions. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
-rw-r--r--arch/sh/kernel/cpu/init.c34
1 files changed, 33 insertions, 1 deletions
diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index ad85421099c..d40b9db5be0 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -3,7 +3,7 @@
*
* CPU init code
*
- * Copyright (C) 2002 - 2007 Paul Mundt
+ * Copyright (C) 2002 - 2009 Paul Mundt
* Copyright (C) 2003 Richard Curnow
*
* This file is subject to the terms and conditions of the GNU General Public
@@ -62,6 +62,37 @@ static void __init speculative_execution_init(void)
#define speculative_execution_init() do { } while (0)
#endif
+#ifdef CONFIG_CPU_SH4A
+#define EXPMASK 0xff2f0004
+#define EXPMASK_RTEDS (1 << 0)
+#define EXPMASK_BRDSSLP (1 << 1)
+#define EXPMASK_MMCAW (1 << 4)
+
+static void __init expmask_init(void)
+{
+ unsigned long expmask = __raw_readl(EXPMASK);
+
+ /*
+ * Future proofing.
+ *
+ * Disable support for slottable sleep instruction
+ * and non-nop instructions in the rte delay slot.
+ */
+ expmask &= ~(EXPMASK_RTEDS | EXPMASK_BRDSSLP);
+
+ /*
+ * Enable associative writes to the memory-mapped cache array
+ * until the cache flush ops have been rewritten.
+ */
+ expmask |= EXPMASK_MMCAW;
+
+ __raw_writel(expmask, EXPMASK);
+ ctrl_barrier();
+}
+#else
+#define expmask_init() do { } while (0)
+#endif
+
/* 2nd-level cache init */
void __uses_jump_to_uncached __attribute__ ((weak)) l2_cache_init(void)
{
@@ -321,4 +352,5 @@ asmlinkage void __init sh_cpu_init(void)
#endif
speculative_execution_init();
+ expmask_init();
}