ARM: 7201/1: add EDAC atomic_scrub function

Add support for architecture specific EDAC atomic_scrub to ARM. Only ARMv6+
is implemented as ldrex/strex instructions are needed. Supporting EDAC on
ARMv5 or earlier is unlikely at this point anyway.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/include/asm/edac.h b/arch/arm/include/asm/edac.h
new file mode 100644 (file)
index 0000000..0df7a2c
--- /dev/null
+++ b/arch/arm/include/asm/edac.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2011 Calxeda, Inc.
+ * Based on PPC version Copyright 2007 MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef ASM_EDAC_H
+#define ASM_EDAC_H
+/*
+ * ECC atomic, DMA, SMP and interrupt safe scrub function.
+ * Implements the per arch atomic_scrub() that EDAC use for software
+ * ECC scrubbing.  It reads memory and then writes back the original
+ * value, allowing the hardware to detect and correct memory errors.
+ */
+static inline void atomic_scrub(void *va, u32 size)
+{
+#if __LINUX_ARM_ARCH__ >= 6
+       unsigned int *virt_addr = va;
+       unsigned int temp, temp2;
+       unsigned int i;
+
+       for (i = 0; i < size / sizeof(*virt_addr); i++, virt_addr++) {
+               /* Very carefully read and write to memory atomically
+                * so we are interrupt, DMA and SMP safe.
+                */
+               __asm__ __volatile__("\n"
+                       "1:     ldrex   %0, [%2]\n"
+                       "       strex   %1, %0, [%2]\n"
+                       "       teq     %1, #0\n"
+                       "       bne     1b\n"
+                       : "=&r"(temp), "=&r"(temp2)
+                       : "r"(virt_addr)
+                       : "cc");
+       }
+#endif
+}
+
+#endif