mvebu: add backported patch to reenable hw i/o coherency

Reported-by: Claudio Leite <leitec@staticky.com>
Signed-off-by: Imre Kaloz <kaloz@openwrt.org>

SVN-Revision: 44621

target/linux/mvebu/patches-3.18/025-ARM-mvebu-Use-arm_coherent_dma_ops.patch

@@ -0,0 +1,111 @@
+From 1bd4d8a6de5cda605e8b99fbf081be2ea2959380 Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Date: Fri, 16 Jan 2015 17:11:29 +0100
+Subject: ARM: mvebu: use arm_coherent_dma_ops and re-enable hardware I/O
+ coherency
+
+Now that we have enabled automatic I/O synchronization barriers, we no
+longer need any explicit barriers. We can therefore simplify
+arch/arm/mach-mvebu/coherency.c by using the existing
+arm_coherent_dma_ops instead of our custom mvebu_hwcc_dma_ops, and
+re-enable hardware I/O coherency support.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+[Andrew Lunn <andrew@lunn.ch>: Remove forgotten comment]
+Signed-off-by: Andrew Lunn <andrew@lunn.ch>
+
+--- a/arch/arm/mach-mvebu/coherency.c
++++ b/arch/arm/mach-mvebu/coherency.c
+@@ -33,6 +33,7 @@
+ #include <asm/smp_plat.h>
+ #include <asm/cacheflush.h>
+ #include <asm/mach/map.h>
++#include <asm/dma-mapping.h>
+ #include "armada-370-xp.h"
+ #include "coherency.h"
+ #include "mvebu-soc-id.h"
+@@ -223,59 +224,6 @@ static void __init armada_375_coherency_
+ 	coherency_wa_enabled = true;
+ }
+ 
+-static inline void mvebu_hwcc_sync_io_barrier(void)
+-{
+-	if (coherency_wa_enabled) {
+-		mvebu_hwcc_armada375_sync_io_barrier_wa();
+-		return;
+-	}
+-
+-	writel(0x1, coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET);
+-	while (readl(coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET) & 0x1);
+-}
+-
+-static dma_addr_t mvebu_hwcc_dma_map_page(struct device *dev, struct page *page,
+-				  unsigned long offset, size_t size,
+-				  enum dma_data_direction dir,
+-				  struct dma_attrs *attrs)
+-{
+-	if (dir != DMA_TO_DEVICE)
+-		mvebu_hwcc_sync_io_barrier();
+-	return pfn_to_dma(dev, page_to_pfn(page)) + offset;
+-}
+-
+-
+-static void mvebu_hwcc_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
+-			      size_t size, enum dma_data_direction dir,
+-			      struct dma_attrs *attrs)
+-{
+-	if (dir != DMA_TO_DEVICE)
+-		mvebu_hwcc_sync_io_barrier();
+-}
+-
+-static void mvebu_hwcc_dma_sync(struct device *dev, dma_addr_t dma_handle,
+-			size_t size, enum dma_data_direction dir)
+-{
+-	if (dir != DMA_TO_DEVICE)
+-		mvebu_hwcc_sync_io_barrier();
+-}
+-
+-static struct dma_map_ops mvebu_hwcc_dma_ops = {
+-	.alloc			= arm_dma_alloc,
+-	.free			= arm_dma_free,
+-	.mmap			= arm_dma_mmap,
+-	.map_page		= mvebu_hwcc_dma_map_page,
+-	.unmap_page		= mvebu_hwcc_dma_unmap_page,
+-	.get_sgtable		= arm_dma_get_sgtable,
+-	.map_sg			= arm_dma_map_sg,
+-	.unmap_sg		= arm_dma_unmap_sg,
+-	.sync_single_for_cpu	= mvebu_hwcc_dma_sync,
+-	.sync_single_for_device	= mvebu_hwcc_dma_sync,
+-	.sync_sg_for_cpu	= arm_dma_sync_sg_for_cpu,
+-	.sync_sg_for_device	= arm_dma_sync_sg_for_device,
+-	.set_dma_mask		= arm_dma_set_mask,
+-};
+-
+ static int mvebu_hwcc_notifier(struct notifier_block *nb,
+ 			       unsigned long event, void *__dev)
+ {
+@@ -283,7 +231,7 @@ static int mvebu_hwcc_notifier(struct no
+ 
+ 	if (event != BUS_NOTIFY_ADD_DEVICE)
+ 		return NOTIFY_DONE;
+-	set_dma_ops(dev, &mvebu_hwcc_dma_ops);
++	set_dma_ops(dev, &arm_coherent_dma_ops);
+ 
+ 	return NOTIFY_OK;
+ }
+@@ -405,14 +353,9 @@ static int coherency_type(void)
+ 	return type;
+ }
+ 
+-/*
+- * As a precaution, we currently completely disable hardware I/O
+- * coherency, until enough testing is done with automatic I/O
+- * synchronization barriers to validate that it is a proper solution.
+- */
+ int coherency_available(void)
+ {
+-	return false;
++	return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
+ }
+ 
+ int __init coherency_init(void)