[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 77aefb4ebedd..3d3e53651341 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 f5903679ee6a..034e8506f6ea 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)