1 files changed, 64 insertions, 0 deletions
diff --git a/kernel/arch/tile/include/asm/cache.h b/kernel/arch/tile/include/asm/cache.h
new file mode 100644
index 000000000..6160761d5
--- /dev/null
+++ b/kernel/arch/tile/include/asm/cache.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#ifndef _ASM_TILE_CACHE_H
+#define _ASM_TILE_CACHE_H
+
+#include <arch/chip.h>
+
+/* bytes per L1 data cache line */
+#define L1_CACHE_SHIFT		CHIP_L1D_LOG_LINE_SIZE()
+#define L1_CACHE_BYTES		(1 << L1_CACHE_SHIFT)
+
+/* bytes per L2 cache line */
+#define L2_CACHE_SHIFT		CHIP_L2_LOG_LINE_SIZE()
+#define L2_CACHE_BYTES		(1 << L2_CACHE_SHIFT)
+#define L2_CACHE_ALIGN(x)	(((x)+(L2_CACHE_BYTES-1)) & -L2_CACHE_BYTES)
+
+/*
+ * TILEPro I/O is not always coherent (networking typically uses coherent
+ * I/O, but PCI traffic does not) and setting ARCH_DMA_MINALIGN to the
+ * L2 cacheline size helps ensure that kernel heap allocations are aligned.
+ * TILE-Gx I/O is always coherent when used on hash-for-home pages.
+ *
+ * However, it's possible at runtime to request not to use hash-for-home
+ * for the kernel heap, in which case the kernel will use flush-and-inval
+ * to manage coherence.  As a result, we use L2_CACHE_BYTES for the
+ * DMA minimum alignment to avoid false sharing in the kernel heap.
+ */
+#define ARCH_DMA_MINALIGN	L2_CACHE_BYTES
+
+/* use the cache line size for the L2, which is where it counts */
+#define SMP_CACHE_BYTES_SHIFT	L2_CACHE_SHIFT
+#define SMP_CACHE_BYTES		L2_CACHE_BYTES
+#define INTERNODE_CACHE_SHIFT   L2_CACHE_SHIFT
+#define INTERNODE_CACHE_BYTES   L2_CACHE_BYTES
+
+/* Group together read-mostly things to avoid cache false sharing */
+#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+
+/*
+ * Originally we used small TLB pages for kernel data and grouped some
+ * things together as "write once", enforcing the property at the end
+ * of initialization by making those pages read-only and non-coherent.
+ * This allowed better cache utilization since cache inclusion did not
+ * need to be maintained.  However, to do this requires an extra TLB
+ * entry, which on balance is more of a performance hit than the
+ * non-coherence is a performance gain, so we now just make "read
+ * mostly" and "write once" be synonyms.  We keep the attribute
+ * separate in case we change our minds at a future date.
+ */
+#define __write_once __read_mostly
+
+#endif /* _ASM_TILE_CACHE_H */