1 files changed, 68 insertions, 0 deletions
diff --git a/arch/metag/mm/maccess.c b/arch/metag/mm/maccess.c
new file mode 100644
index 000000000000..eba2cfc935b1
--- /dev/null
+++ b/arch/metag/mm/maccess.c
@@ -0,0 +1,68 @@
+/*
+ * safe read and write memory routines callable while atomic
+ *
+ * Copyright 2012 Imagination Technologies
+ */
+
+#include <linux/uaccess.h>
+#include <asm/io.h>
+
+/*
+ * The generic probe_kernel_write() uses the user copy code which can split the
+ * writes if the source is unaligned, and repeats writes to make exceptions
+ * precise. We override it here to avoid these things happening to memory mapped
+ * IO memory where they could have undesired effects.
+ * Due to the use of CACHERD instruction this only works on Meta2 onwards.
+ */
+#ifdef CONFIG_METAG_META21
+long probe_kernel_write(void *dst, const void *src, size_t size)
+{
+	unsigned long ldst = (unsigned long)dst;
+	void __iomem *iodst = (void __iomem *)dst;
+	unsigned long lsrc = (unsigned long)src;
+	const u8 *psrc = (u8 *)src;
+	unsigned int pte, i;
+	u8 bounce[8] __aligned(8);
+
+	if (!size)
+		return 0;
+
+	/* Use the write combine bit to decide is the destination is MMIO. */
+	pte = __builtin_meta2_cacherd(dst);
+
+	/* Check the mapping is valid and writeable. */
+	if ((pte & (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT))
+	    != (MMCU_ENTRY_WR_BIT | MMCU_ENTRY_VAL_BIT))
+		return -EFAULT;
+
+	/* Fall back to generic version for cases we're not interested in. */
+	if (pte & MMCU_ENTRY_WRC_BIT	|| /* write combined memory */
+	    (ldst & (size - 1))		|| /* destination unaligned */
+	    size > 8			|| /* more than max write size */
+	    (size & (size - 1)))	   /* non power of 2 size */
+		return __probe_kernel_write(dst, src, size);
+
+	/* If src is unaligned, copy to the aligned bounce buffer first. */
+	if (lsrc & (size - 1)) {
+		for (i = 0; i < size; ++i)
+			bounce[i] = psrc[i];
+		psrc = bounce;
+	}
+
+	switch (size) {
+	case 1:
+		writeb(*psrc, iodst);
+		break;
+	case 2:
+		writew(*(const u16 *)psrc, iodst);
+		break;
+	case 4:
+		writel(*(const u32 *)psrc, iodst);
+		break;
+	case 8:
+		writeq(*(const u64 *)psrc, iodst);
+		break;
+	}
+	return 0;
+}
+#endif