v4.19.13 snapshot.
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
new file mode 100644
index 0000000..c75d5c3
--- /dev/null
+++ b/arch/arc/mm/dma.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/dma-noncoherent.h>
+#include <asm/cache.h>
+#include <asm/cacheflush.h>
+
+/*
+ * ARCH specific callbacks for generic noncoherent DMA ops (dma/noncoherent.c)
+ * - hardware IOC not available (or "dma-coherent" not set for device in DT)
+ * - But still handle both coherent and non-coherent requests from caller
+ *
+ * For DMA coherent hardware (IOC) generic code suffices
+ */
+void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+ gfp_t gfp, unsigned long attrs)
+{
+ unsigned long order = get_order(size);
+ struct page *page;
+ phys_addr_t paddr;
+ void *kvaddr;
+ bool need_coh = !(attrs & DMA_ATTR_NON_CONSISTENT);
+
+ /*
+ * __GFP_HIGHMEM flag is cleared by upper layer functions
+ * (in include/linux/dma-mapping.h) so we should never get a
+ * __GFP_HIGHMEM here.
+ */
+ BUG_ON(gfp & __GFP_HIGHMEM);
+
+ page = alloc_pages(gfp, order);
+ if (!page)
+ return NULL;
+
+ /* This is linear addr (0x8000_0000 based) */
+ paddr = page_to_phys(page);
+
+ *dma_handle = paddr;
+
+ /*
+ * A coherent buffer needs MMU mapping to enforce non-cachability.
+ * kvaddr is kernel Virtual address (0x7000_0000 based).
+ */
+ if (need_coh) {
+ kvaddr = ioremap_nocache(paddr, size);
+ if (kvaddr == NULL) {
+ __free_pages(page, order);
+ return NULL;
+ }
+ } else {
+ kvaddr = (void *)(u32)paddr;
+ }
+
+ /*
+ * Evict any existing L1 and/or L2 lines for the backing page
+ * in case it was used earlier as a normal "cached" page.
+ * Yeah this bit us - STAR 9000898266
+ *
+ * Although core does call flush_cache_vmap(), it gets kvaddr hence
+ * can't be used to efficiently flush L1 and/or L2 which need paddr
+ * Currently flush_cache_vmap nukes the L1 cache completely which
+ * will be optimized as a separate commit
+ */
+ if (need_coh)
+ dma_cache_wback_inv(paddr, size);
+
+ return kvaddr;
+}
+
+void arch_dma_free(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_handle, unsigned long attrs)
+{
+ phys_addr_t paddr = dma_handle;
+ struct page *page = virt_to_page(paddr);
+
+ if (!(attrs & DMA_ATTR_NON_CONSISTENT))
+ iounmap((void __force __iomem *)vaddr);
+
+ __free_pages(page, get_order(size));
+}
+
+int arch_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ unsigned long attrs)
+{
+ unsigned long user_count = vma_pages(vma);
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ unsigned long pfn = __phys_to_pfn(dma_addr);
+ unsigned long off = vma->vm_pgoff;
+ int ret = -ENXIO;
+
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+ if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
+ return ret;
+
+ if (off < count && user_count <= (count - off)) {
+ ret = remap_pfn_range(vma, vma->vm_start,
+ pfn + off,
+ user_count << PAGE_SHIFT,
+ vma->vm_page_prot);
+ }
+
+ return ret;
+}
+
+/*
+ * Cache operations depending on function and direction argument, inspired by
+ * https://lkml.org/lkml/2018/5/18/979
+ * "dma_sync_*_for_cpu and direction=TO_DEVICE (was Re: [PATCH 02/20]
+ * dma-mapping: provide a generic dma-noncoherent implementation)"
+ *
+ * | map == for_device | unmap == for_cpu
+ * |----------------------------------------------------------------
+ * TO_DEV | writeback writeback | none none
+ * FROM_DEV | invalidate invalidate | invalidate* invalidate*
+ * BIDIR | writeback+inv writeback+inv | invalidate invalidate
+ *
+ * [*] needed for CPU speculative prefetches
+ *
+ * NOTE: we don't check the validity of direction argument as it is done in
+ * upper layer functions (in include/linux/dma-mapping.h)
+ */
+
+void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir)
+{
+ switch (dir) {
+ case DMA_TO_DEVICE:
+ dma_cache_wback(paddr, size);
+ break;
+
+ case DMA_FROM_DEVICE:
+ dma_cache_inv(paddr, size);
+ break;
+
+ case DMA_BIDIRECTIONAL:
+ dma_cache_wback_inv(paddr, size);
+ break;
+
+ default:
+ break;
+ }
+}
+
+void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir)
+{
+ switch (dir) {
+ case DMA_TO_DEVICE:
+ break;
+
+ /* FROM_DEVICE invalidate needed if speculative CPU prefetch only */
+ case DMA_FROM_DEVICE:
+ case DMA_BIDIRECTIONAL:
+ dma_cache_inv(paddr, size);
+ break;
+
+ default:
+ break;
+ }
+}
+
+/*
+ * Plug in coherent or noncoherent dma ops
+ */
+void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ const struct iommu_ops *iommu, bool coherent)
+{
+ /*
+ * IOC hardware snoops all DMA traffic keeping the caches consistent
+ * with memory - eliding need for any explicit cache maintenance of
+ * DMA buffers - so we can use dma_direct cache ops.
+ */
+ if (is_isa_arcv2() && ioc_enable && coherent) {
+ set_dma_ops(dev, &dma_direct_ops);
+ dev_info(dev, "use dma_direct_ops cache ops\n");
+ } else {
+ set_dma_ops(dev, &dma_noncoherent_ops);
+ dev_info(dev, "use dma_noncoherent_ops cache ops\n");
+ }
+}