MIPS: Add __ioread64_copy

We currently have __ioread32_copy, __iowrite32_copy & __iowrite64_copy
helpers in lib/iomap_copy.c. This patch adds __ioread64_copy to round
out the set, allowing copies from I/O memory using 32 or 64 bit reads.

[ralf@linux-mips.org: Changed to move all the code of this patch to be
applied to arch/mips temporarily.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17025/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/io.h

@@ -632,4 +632,6 @@ extern void (*_dma_cache_inv)(unsigned long start, unsigned long size);
  */
 #define xlate_dev_kmem_ptr(p)	p
 
+void __ioread64_copy(void *to, const void __iomem *from, size_t count);
+
 #endif /* _ASM_IO_H */

arch/mips/lib/Makefile

@@ -6,7 +6,7 @@ lib-y	+= bitops.o csum_partial.o delay.o memcpy.o memset.o \
 	   mips-atomic.o strncpy_user.o \
 	   strnlen_user.o uncached.o
 
-obj-y			+= iomap.o
+obj-y			+= iomap.o iomap_copy.o
 obj-$(CONFIG_PCI)	+= iomap-pci.o
 lib-$(CONFIG_GENERIC_CSUM)	:= $(filter-out csum_partial.o, $(lib-y))
 

arch/mips/lib/iomap_copy.c

+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * 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.  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, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/export.h>
+#include <linux/io.h>
+
+/**
+ * __ioread64_copy - copy data from MMIO space, in 64-bit units
+ * @to: destination (must be 64-bit aligned)
+ * @from: source, in MMIO space (must be 64-bit aligned)
+ * @count: number of 64-bit quantities to copy
+ *
+ * Copy data from MMIO space to kernel 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 __ioread64_copy(void *to, const void __iomem *from, size_t count)
+{
+#ifdef CONFIG_64BIT
+	u64 *dst = to;
+	const u64 __iomem *src = from;
+	const u64 __iomem *end = src + count;
+
+	while (src < end)
+		*dst++ = __raw_readq(src++);
+#else
+	__ioread32_copy(to, from, count * 2);
+#endif
+}
+EXPORT_SYMBOL_GPL(__ioread64_copy);