[MIPS] Allow setting of the cache attribute at run time.

Slightly tacky, but there is a precedent in the sparc archirecture code.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 41 insertions, 9 deletions

diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 77aefb4ebed..3d3e5365134 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -14,6 +14,7 @@
 #include <linux/linkage.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
+#include <linux/module.h>
 #include <linux/bitops.h>
 
 #include <asm/bcache.h>
@@ -1216,9 +1217,25 @@ void au1x00_fixup_config_od(void)
 	}
 }
 
+static int __cpuinitdata cca = -1;
+
+static int __init cca_setup(char *str)
+{
+	get_option(&str, &cca);
+
+	return 1;
+}
+
+__setup("cca=", cca_setup);
+
 static void __cpuinit coherency_setup(void)
 {
-	change_c0_config(CONF_CM_CMASK, CONF_CM_DEFAULT);
+	if (cca < 0 || cca > 7)
+		cca = read_c0_config() & CONF_CM_CMASK;
+	_page_cachable_default = cca << _CACHE_SHIFT;
+
+	pr_debug("Using cache attribute %d\n", cca);
+	change_c0_config(CONF_CM_CMASK, cca);
 
 	/*
 	 * c0_status.cu=0 specifies that updates by the sc instruction use
diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index f5903679ee6..034e8506f6e 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -130,8 +130,28 @@ void __update_cache(struct vm_area_struct *vma, unsigned long address,
 	}
 }
 
-static char cache_panic[] __cpuinitdata =
-	"Yeee, unsupported cache architecture.";
+unsigned long _page_cachable_default;
+EXPORT_SYMBOL_GPL(_page_cachable_default);
+
+static inline void setup_protection_map(void)
+{
+	protection_map[0] = PAGE_NONE;
+	protection_map[1] = PAGE_READONLY;
+	protection_map[2] = PAGE_COPY;
+	protection_map[3] = PAGE_COPY;
+	protection_map[4] = PAGE_READONLY;
+	protection_map[5] = PAGE_READONLY;
+	protection_map[6] = PAGE_COPY;
+	protection_map[7] = PAGE_COPY;
+	protection_map[8] = PAGE_NONE;
+	protection_map[9] = PAGE_READONLY;
+	protection_map[10] = PAGE_SHARED;
+	protection_map[11] = PAGE_SHARED;
+	protection_map[12] = PAGE_READONLY;
+	protection_map[13] = PAGE_READONLY;
+	protection_map[14] = PAGE_SHARED;
+	protection_map[15] = PAGE_SHARED;
+}
 
 void __devinit cpu_cache_init(void)
 {
@@ -139,34 +159,29 @@ void __devinit cpu_cache_init(void)
 		extern void __weak r3k_cache_init(void);
 
 		r3k_cache_init();
-		return;
 	}
 	if (cpu_has_6k_cache) {
 		extern void __weak r6k_cache_init(void);
 
 		r6k_cache_init();
-		return;
 	}
 	if (cpu_has_4k_cache) {
 		extern void __weak r4k_cache_init(void);
 
 		r4k_cache_init();
-		return;
 	}
 	if (cpu_has_8k_cache) {
 		extern void __weak r8k_cache_init(void);
 
 		r8k_cache_init();
-		return;
 	}
 	if (cpu_has_tx39_cache) {
 		extern void __weak tx39_cache_init(void);
 
 		tx39_cache_init();
-		return;
 	}
 
-	panic(cache_panic);
+	setup_protection_map();
 }
 
 int __weak __uncached_access(struct file *file, unsigned long addr)