include/asm-:mips add missing edac h file

EDAC has a foundation to perform software memory scrubbing, but it requires a
per architecture (atomic_scrub) function for performing an atomic update
operation.  Under X86, this is done with a

lock:  add  [addr],0

in the file asm-x86/edac.h

This patch provides the MIPS arch with that atomic function, atomic_scrub() in

asm-mips/edac.h

Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/include/asm-mips/edac.h b/include/asm-mips/edac.h
new file mode 100644
index 000000000000..83719eee2d13
--- /dev/null
+++ b/include/asm-mips/edac.h
@@ -0,0 +1,35 @@
+#ifndef ASM_EDAC_H
+#define ASM_EDAC_H
+
+/* ECC atomic, DMA, SMP and interrupt safe scrub function */
+
+static inline void atomic_scrub(void *va, u32 size)
+{
+        unsigned long *virt_addr = va;
+        unsigned long temp;
+        u32 i;
+
+        for (i = 0; i < size / sizeof(unsigned long); i++, virt_addr++) {
+
+                /*
+                 * Very carefully read and write to memory atomically
+                 * so we are interrupt, DMA and SMP safe.
+                 *
+                 * Intel: asm("lock; addl $0, %0"::"m"(*virt_addr));
+                 */
+
+                __asm__ __volatile__ (
+                "       .set    mips3                                   \n"
+                "1:     ll      %0, %1          # atomic_add            \n"
+                "       ll      %0, %1          # atomic_add            \n"
+                "       addu    %0, $0                                  \n"
+                "       sc      %0, %1                                  \n"
+                "       beqz    %0, 1b                                  \n"
+                "       .set    mips0                                   \n"
+                : "=&r" (temp), "=m" (*virt_addr)
+                : "m" (*virt_addr));
+
+        }
+}
+
+#endif