powerpc: implement the DMA_ATTR_NO_WARN attribute

BugLink: http://bugs.launchpad.net/bugs/1633128

Add support for the DMA_ATTR_NO_WARN attribute on powerpc iommu code.

Link: http://lkml.kernel.org/r/1470092390-25451-3-git-send-email-mauricfo@linux.vnet.ibm.comSigned-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(back ported from commit af8a2498)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

(rtg - Use dma_get_attr())
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>

arch/powerpc/kernel/iommu.c

@@ -479,7 +479,8 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 
 		/* Handle failure */
 		if (unlikely(entry == DMA_ERROR_CODE)) {
-			if (printk_ratelimit())
+			if (!(dma_get_attr(DMA_ATTR_NO_WARN, attrs)) &&
+			    printk_ratelimit())
 				dev_info(dev, "iommu_alloc failed, tbl %p "
 					 "vaddr %lx npages %lu\n", tbl, vaddr,
 					 npages);
@@ -776,7 +777,8 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
 					 mask >> tbl->it_page_shift, align,
 					 attrs);
 		if (dma_handle == DMA_ERROR_CODE) {
-			if (printk_ratelimit())  {
+			if (!(dma_get_attr(DMA_ATTR_NO_WARN, attrs)) &&
+			    printk_ratelimit())  {
 				dev_info(dev, "iommu_alloc failed, tbl %p "
 					 "vaddr %p npages %d\n", tbl, vaddr,
 					 npages);