1 files changed, 221 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
new file mode 100644
index 000000000..8920862ff
--- /dev/null
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
+ *
+ * Provide default implementations of the DMA mapping callbacks for
+ * busses using the iommu infrastructure
+ */
+
+#include <linux/dma-direct.h>
+#include <linux/pci.h>
+#include <asm/iommu.h>
+
+#ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT
+#define can_map_direct(dev, addr) \
+	((dev)->bus_dma_limit >= phys_to_dma((dev), (addr)))
+
+bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr)
+{
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	return can_map_direct(dev, addr);
+}
+
+#define is_direct_handle(dev, h) ((h) >= (dev)->archdata.dma_offset)
+
+bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle)
+{
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	return is_direct_handle(dev, dma_handle);
+}
+
+bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg,
+			    int nents)
+{
+	struct scatterlist *s;
+	int i;
+
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	for_each_sg(sg, s, nents, i) {
+		if (!can_map_direct(dev, sg_phys(s) + s->offset + s->length))
+			return false;
+	}
+
+	return true;
+}
+
+bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg,
+			      int nents)
+{
+	struct scatterlist *s;
+	int i;
+
+	if (likely(!dev->bus_dma_limit))
+		return false;
+
+	for_each_sg(sg, s, nents, i) {
+		if (!is_direct_handle(dev, s->dma_address + s->length))
+			return false;
+	}
+
+	return true;
+}
+#endif /* CONFIG_ARCH_HAS_DMA_MAP_DIRECT */
+
+/*
+ * Generic iommu implementation
+ */
+
+/* Allocates a contiguous real buffer and creates mappings over it.
+ * Returns the virtual address of the buffer and sets dma_handle
+ * to the dma address (mapping) of the first page.
+ */
+static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
+				      dma_addr_t *dma_handle, gfp_t flag,
+				      unsigned long attrs)
+{
+	return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
+				    dma_handle, dev->coherent_dma_mask, flag,
+				    dev_to_node(dev));
+}
+
+static void dma_iommu_free_coherent(struct device *dev, size_t size,
+				    void *vaddr, dma_addr_t dma_handle,
+				    unsigned long attrs)
+{
+	iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
+}
+
+/* Creates TCEs for a user provided buffer.  The user buffer must be
+ * contiguous real kernel storage (not vmalloc).  The address passed here
+ * comprises a page address and offset into that page. The dma_addr_t
+ * returned will point to the same byte within the page as was passed in.
+ */
+static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
+				     unsigned long offset, size_t size,
+				     enum dma_data_direction direction,
+				     unsigned long attrs)
+{
+	return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
+			      size, dma_get_mask(dev), direction, attrs);
+}
+
+
+static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
+				 size_t size, enum dma_data_direction direction,
+				 unsigned long attrs)
+{
+	iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
+			 attrs);
+}
+
+
+static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
+			    int nelems, enum dma_data_direction direction,
+			    unsigned long attrs)
+{
+	return ppc_iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
+				dma_get_mask(dev), direction, attrs);
+}
+
+static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
+		int nelems, enum dma_data_direction direction,
+		unsigned long attrs)
+{
+	ppc_iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems,
+			   direction, attrs);
+}
+
+static bool dma_iommu_bypass_supported(struct device *dev, u64 mask)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pci_controller *phb = pci_bus_to_host(pdev->bus);
+
+	if (iommu_fixed_is_weak || !phb->controller_ops.iommu_bypass_supported)
+		return false;
+	return phb->controller_ops.iommu_bypass_supported(pdev, mask);
+}
+
+/* We support DMA to/from any memory page via the iommu */
+int dma_iommu_dma_supported(struct device *dev, u64 mask)
+{
+	struct iommu_table *tbl;
+
+	if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
+		/*
+		 * dma_iommu_bypass_supported() sets dma_max when there is
+		 * 1:1 mapping but it is somehow limited.
+		 * ibm,pmemory is one example.
+		 */
+		dev->dma_ops_bypass = dev->bus_dma_limit == 0;
+		if (!dev->dma_ops_bypass)
+			dev_warn(dev,
+				 "iommu: 64-bit OK but direct DMA is limited by %llx\n",
+				 dev->bus_dma_limit);
+		else
+			dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
+		return 1;
+	}
+
+	tbl = get_iommu_table_base(dev);
+
+	if (!tbl) {
+		dev_err(dev, "Warning: IOMMU dma not supported: mask 0x%08llx, table unavailable\n", mask);
+		return 0;
+	}
+
+	if (tbl->it_offset > (mask >> tbl->it_page_shift)) {
+		dev_info(dev, "Warning: IOMMU offset too big for device mask\n");
+		dev_info(dev, "mask: 0x%08llx, table offset: 0x%08lx\n",
+				mask, tbl->it_offset << tbl->it_page_shift);
+		return 0;
+	}
+
+	dev_dbg(dev, "iommu: not 64-bit, using default ops\n");
+	dev->dma_ops_bypass = false;
+	return 1;
+}
+
+u64 dma_iommu_get_required_mask(struct device *dev)
+{
+	struct iommu_table *tbl = get_iommu_table_base(dev);
+	u64 mask;
+
+	if (dev_is_pci(dev)) {
+		u64 bypass_mask = dma_direct_get_required_mask(dev);
+
+		if (dma_iommu_dma_supported(dev, bypass_mask)) {
+			dev_info(dev, "%s: returning bypass mask 0x%llx\n", __func__, bypass_mask);
+			return bypass_mask;
+		}
+	}
+
+	if (!tbl)
+		return 0;
+
+	mask = 1ULL << (fls_long(tbl->it_offset + tbl->it_size) +
+			tbl->it_page_shift - 1);
+	mask += mask - 1;
+
+	return mask;
+}
+
+const struct dma_map_ops dma_iommu_ops = {
+	.alloc			= dma_iommu_alloc_coherent,
+	.free			= dma_iommu_free_coherent,
+	.map_sg			= dma_iommu_map_sg,
+	.unmap_sg		= dma_iommu_unmap_sg,
+	.dma_supported		= dma_iommu_dma_supported,
+	.map_page		= dma_iommu_map_page,
+	.unmap_page		= dma_iommu_unmap_page,
+	.get_required_mask	= dma_iommu_get_required_mask,
+	.mmap			= dma_common_mmap,
+	.get_sgtable		= dma_common_get_sgtable,
+	.alloc_pages		= dma_common_alloc_pages,
+	.free_pages		= dma_common_free_pages,
+};