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[PATCH] add __iowrite64_copy

Introduce __iowrite64_copy.  It will be used by the Myri-10G Ethernet
driver to post requests to the NIC.  This driver will be submitted soon.

__iowrite64_copy copies to I/O memory in units of 64 bits when possible (on
64 bit architectures).  It reverts to __iowrite32_copy on 32 bit
architectures.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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commit 22ae813b85df7c0b0fc7c8d6f336d6a9f566ff97 1 parent 34641a5
Brice Goglin authored Linus Torvalds committed
Showing with 29 additions and 0 deletions.
  1. +1 −0  include/linux/io.h
  2. +28 −0 lib/iomap_copy.c
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1  include/linux/io.h
@@ -21,5 +21,6 @@
#include <asm/io.h>
void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
+void __iowrite64_copy(void __iomem *to, const void *from, size_t count);
#endif /* _LINUX_IO_H */
View
28 lib/iomap_copy.c
@@ -40,3 +40,31 @@ void __attribute__((weak)) __iowrite32_copy(void __iomem *to,
__raw_writel(*src++, dst++);
}
EXPORT_SYMBOL_GPL(__iowrite32_copy);
+
+/**
+ * __iowrite64_copy - copy data to MMIO space, in 64-bit or 32-bit units
+ * @to: destination, in MMIO space (must be 64-bit aligned)
+ * @from: source (must be 64-bit aligned)
+ * @count: number of 64-bit quantities to copy
+ *
+ * Copy data from kernel space to MMIO space, in units of 32 or 64 bits at a
+ * time. Order of access is not guaranteed, nor is a memory barrier
+ * performed afterwards.
+ */
+void __attribute__((weak)) __iowrite64_copy(void __iomem *to,
+ const void *from,
+ size_t count)
+{
+#ifdef CONFIG_64BIT
+ u64 __iomem *dst = to;
+ const u64 *src = from;
+ const u64 *end = src + count;
+
+ while (src < end)
+ __raw_writeq(*src++, dst++);
+#else
+ __iowrite32_copy(to, from, count * 2);
+#endif
+}
+
+EXPORT_SYMBOL_GPL(__iowrite64_copy);
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