Ported pcie-brcmstb bounce buffer implementation to ARM64. (#3144)

Ported pcie-brcmstb bounce buffer implementation to ARM64.
This enables full 4G RAM usage on Raspberry Pi in 64-bit mode.

Signed-off-by: Yaroslav Rosomakho <[email protected]>

Author: yaroslavros

arch/arm64/mm/dma-mapping.c

@@ -31,6 +31,35 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 }
 
 #ifdef CONFIG_IOMMU_DMA
+static int __swiotlb_get_sgtable_page(struct sg_table *sgt,
+				      struct page *page, size_t size)
+{
+	int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+
+	if (!ret)
+		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+
+	return ret;
+}
+
+static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
+			      unsigned long pfn, size_t size)
+{
+	int ret = -ENXIO;
+	unsigned long nr_vma_pages = vma_pages(vma);
+	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	unsigned long off = vma->vm_pgoff;
+
+	if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
+		ret = remap_pfn_range(vma, vma->vm_start,
+				      pfn + off,
+				      vma->vm_end - vma->vm_start,
+				      vma->vm_page_prot);
+	}
+
+	return ret;
+}
+
 void arch_teardown_dma_ops(struct device *dev)
 {
 	dev->dma_ops = NULL;

drivers/pci/controller/Makefile

@@ -31,6 +31,9 @@ obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
 ifdef CONFIG_ARM
 obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb-bounce.o
 endif
+ifdef CONFIG_ARM64
+obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb-bounce64.o
+endif
 
 obj-$(CONFIG_VMD) += vmd.o
 # pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW

drivers/pci/controller/pcie-brcmstb-bounce.h

@@ -6,7 +6,7 @@
 #ifndef _PCIE_BRCMSTB_BOUNCE_H
 #define _PCIE_BRCMSTB_BOUNCE_H
 
-#ifdef CONFIG_ARM
+#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
 
 int brcm_pcie_bounce_init(struct device *dev, unsigned long buffer_size,
 			  dma_addr_t threshold);