xtensa: initialize atomctl SR

In order to use S32C1I instruction on cores with ATOMCTL SR the register
must be properly initialized.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

2 files changed, 58 insertions, 0 deletions

diff --git a/arch/xtensa/include/asm/initialize_mmu.h b/arch/xtensa/include/asm/initialize_mmu.h
new file mode 100644
index 000000000000..e1f8ba4061ed
--- /dev/null
+++ b/arch/xtensa/include/asm/initialize_mmu.h
@@ -0,0 +1,55 @@
+/*
+ * arch/xtensa/include/asm/initialize_mmu.h
+ *
+ * Initializes MMU:
+ *
+ *      For the new V3 MMU we remap the TLB from virtual == physical
+ *      to the standard Linux mapping used in earlier MMU's.
+ *
+ *      The the MMU we also support a new configuration register that
+ *      specifies how the S32C1I instruction operates with the cache
+ *      controller.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file "COPYING" in the main directory of
+ * this archive for more details.
+ *
+ * Copyright (C) 2008 - 2012 Tensilica, Inc.
+ *
+ *   Marc Gauthier <marc@tensilica.com>
+ *   Pete Delaney <piet@tensilica.com>
+ */
+
+#ifndef _XTENSA_INITIALIZE_MMU_H
+#define _XTENSA_INITIALIZE_MMU_H
+
+#ifdef __ASSEMBLY__
+
+#define XTENSA_HWVERSION_RC_2009_0 230000
+
+        .macro  initialize_mmu
+
+#if XCHAL_HAVE_S32C1I && (XCHAL_HW_MIN_VERSION >= XTENSA_HWVERSION_RC_2009_0)
+/*
+ * We Have Atomic Operation Control (ATOMCTL) Register; Initialize it.
+ * For details see Documentation/xtensa/atomctl.txt
+ */
+#if XCHAL_DCACHE_IS_COHERENT
+        movi    a3, 0x25        /* For SMP/MX -- internal for writeback,
+                                 * RCW otherwise
+                                 */
+#else
+        movi    a3, 0x29        /* non-MX -- Most cores use Std Memory
+                                 * Controlers which usually can't use RCW
+                                 */
+#endif
+        wsr     a3, atomctl
+#endif  /* XCHAL_HAVE_S32C1I &&
+         * (XCHAL_HW_MIN_VERSION >= XTENSA_HWVERSION_RC_2009_0)
+         */
+
+        .endm
+
+#endif /*__ASSEMBLY__*/
+
+#endif /* _XTENSA_INITIALIZE_MMU_H */
diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S
index 417998c02108..9013ae0174f8 100644
--- a/arch/xtensa/kernel/head.S
+++ b/arch/xtensa/kernel/head.S
@@ -18,6 +18,7 @@
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/cacheasm.h>
+#include <asm/initialize_mmu.h>
 
 #include <linux/init.h>
 #include <linux/linkage.h>
@@ -155,6 +156,8 @@ ENTRY(_startup)
 
         isync
 
+        initialize_mmu
+
         /* Unpack data sections
          *
          * The linker script used to build the Linux kernel image