[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>

8 files changed, 45 insertions, 26 deletions

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index fd7124c1b75a..f18cf92650e3 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -73,14 +73,4 @@ config RUNTIME_DEBUG
           include/asm-mips/debug.h for debuging macros.
           If unsure, say N.
 
-config MIPS_UNCACHED
-        bool "Run uncached"
-        depends on DEBUG_KERNEL && !SMP && !SGI_IP27
-        help
-          If you say Y here there kernel will disable all CPU caches.  This will
-          reduce the system's performance dramatically but can help finding
-          otherwise hard to track bugs.  It can also useful if you're doing
-          hardware debugging with a logic analyzer and need to see all traffic
-          on the bus.
-
 endmenu
diff --git a/arch/mips/configs/mipssim_defconfig b/arch/mips/configs/mipssim_defconfig
index 6db0bdaefb27..4f6bce99d5cf 100644
--- a/arch/mips/configs/mipssim_defconfig
+++ b/arch/mips/configs/mipssim_defconfig
@@ -641,7 +641,6 @@ CONFIG_CROSSCOMPILE=y
 CONFIG_CMDLINE="nfsroot=192.168.192.169:/u1/mipsel,timeo=20 ip=dhcp"
 # CONFIG_DEBUG_STACK_USAGE is not set
 # CONFIG_RUNTIME_DEBUG is not set
-# CONFIG_MIPS_UNCACHED is not set
 
 #
 # Security options
diff --git a/arch/mips/configs/pnx8550-jbs_defconfig b/arch/mips/configs/pnx8550-jbs_defconfig
index 518a60892b78..780c7fc24b82 100644
--- a/arch/mips/configs/pnx8550-jbs_defconfig
+++ b/arch/mips/configs/pnx8550-jbs_defconfig
@@ -1223,7 +1223,6 @@ CONFIG_CMDLINE="console=ttyS1,38400n8 kgdb=ttyS0 root=/dev/nfs ip=bootp"
 # CONFIG_KGDB is not set
 CONFIG_SYS_SUPPORTS_KGDB=y
 # CONFIG_RUNTIME_DEBUG is not set
-# CONFIG_MIPS_UNCACHED is not set
 
 #
 # Security options
diff --git a/arch/mips/configs/pnx8550-stb810_defconfig b/arch/mips/configs/pnx8550-stb810_defconfig
index 68351eb81bc8..267f21ed1d0f 100644
--- a/arch/mips/configs/pnx8550-stb810_defconfig
+++ b/arch/mips/configs/pnx8550-stb810_defconfig
@@ -1213,7 +1213,6 @@ CONFIG_CMDLINE="console=ttyS1,38400n8 kgdb=ttyS0 root=/dev/nfs ip=bootp"
 # CONFIG_KGDB is not set
 CONFIG_SYS_SUPPORTS_KGDB=y
 # CONFIG_RUNTIME_DEBUG is not set
-# CONFIG_MIPS_UNCACHED is not set
 
 #
 # Security options
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)
diff --git a/arch/mips/philips/pnx8550/jbs/board_setup.c b/arch/mips/philips/pnx8550/jbs/board_setup.c
index f92826e0096d..e550a3e12f65 100644
--- a/arch/mips/philips/pnx8550/jbs/board_setup.c
+++ b/arch/mips/philips/pnx8550/jbs/board_setup.c
@@ -53,8 +53,8 @@ void __init board_setup(void)
 
         /* clear all three cache coherency fields */
         config0 &= ~(0x7 | (7<<25) | (7<<28));
-        config0 |= (CONF_CM_DEFAULT | (CONF_CM_DEFAULT<<25) |
-                        (CONF_CM_DEFAULT<<28));
+        config0 |= (_page_cachable_default >> _CACHE_SHIFT) |
+                   (CONF_CM_DEFAULT << 25) | (CONF_CM_DEFAULT << 28);
         write_c0_config(config0);
         BARRIER;
 
diff --git a/arch/mips/philips/pnx8550/stb810/board_setup.c b/arch/mips/philips/pnx8550/stb810/board_setup.c
index 345d71e53cf2..d461d7a62365 100644
--- a/arch/mips/philips/pnx8550/stb810/board_setup.c
+++ b/arch/mips/philips/pnx8550/stb810/board_setup.c
@@ -39,8 +39,8 @@ void __init board_setup(void)
 
         /* clear all three cache coherency fields */
         config0 &= ~(0x7 | (7<<25) | (7<<28));
-        config0 |= (CONF_CM_DEFAULT | (CONF_CM_DEFAULT<<25) |
-                        (CONF_CM_DEFAULT<<28));
+        config0 |= (_page_cachable_default >> _CACHE_SHIFT) |
+                   (CONF_CM_DEFAULT << 25) | (CONF_CM_DEFAULT << 28);
         write_c0_config(config0);
 
         configpr = read_c0_config7();