[PATCH] ACPI / scan: Support multiple dma windows with different offsets

[Jianmin Lv]

For DT, of_dma_get_range returns bus_dma_region typed dma regions,
which makes multiple dma windows with different offset available
for translation between dma address and cpu address.

But for ACPI, acpi_dma_get_range doesn't return similar dma regions,
causing no path for setting dev->dma_range_map conveniently. So the
patch changes acpi_dma_get_range and returns bus_dma_region typed
dma regions according to of_dma_get_range.

After changing acpi_dma_get_range, original part of internal code
only available for ARM is moved to acpi_arch_dma_setup for remaining
unchanged.

Signed-off-by: Jianmin Lv <lvjianmin@xxxxxxxxxxx>

diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
index f16739a..840f918 100644
--- a/drivers/acpi/arm64/dma.c
+++ b/drivers/acpi/arm64/dma.c
@@ -9,6 +9,7 @@ void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 	int ret;
 	u64 end, mask;
 	u64 dmaaddr = 0, size = 0, offset = 0;
+	const struct bus_dma_region *map = NULL;
 
 	/*
 	 * If @dev is expected to be DMA-capable then the bus code that created
@@ -26,10 +27,37 @@ void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 	else
 		size = 1ULL << 32;
 
-	ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
+	ret = acpi_dma_get_range(dev, &map);
 	if (ret == -ENODEV)
 		ret = iort_dma_get_ranges(dev, &size);
 	if (!ret) {
+		const struct bus_dma_region *r = map;
+		u64 len, dma_start, dma_end = 0;
+
+		/* determine the overall bounds of all dma regions */
+		for (dma_start = U64_MAX; r->size; r++) {
+			if (offset && r->offset != offset) {
+				dev_warn(dev, "Can't handle multiple windows with different offsets\n");
+				return;
+			}
+			offset = r->offset;
+
+			/* Take lower and upper limits */
+			if (r->dma_start < dma_start)
+				dma_start = r->dma_start;
+			if (r->dma_start + r->size - 1 > dma_end)
+				dma_end = r->dma_start + r->size - 1;
+		}
+
+		if (dma_start >= dma_end) {
+			dev_dbg(dev, "Invalid DMA regions configuration\n");
+			return;
+		}
+
+		dmaaddr = dma_start;
+		len = dma_end - dma_start;
+		size = max(len, len + 1);
+
 		/*
 		 * Limit coherent and dma mask based on size retrieved from
 		 * firmware.
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 762b61f..8961b51 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -20,6 +20,7 @@
 #include <linux/platform_data/x86/apple.h>
 #include <linux/pgtable.h>
 #include <linux/crc32.h>
+#include <linux/dma-direct.h>
 
 #include "internal.h"
 
@@ -1492,15 +1493,15 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
  *
  * Return 0 on success, < 0 on failure.
  */
-int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
-		       u64 *size)
+int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
 {
 	struct acpi_device *adev;
 	LIST_HEAD(list);
 	struct resource_entry *rentry;
 	int ret;
 	struct device *dma_dev = dev;
-	u64 len, dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
+	int num_ranges = 0;
+	struct bus_dma_region *r;
 
 	/*
 	 * Walk the device tree chasing an ACPI companion with a _DMA
@@ -1525,31 +1526,31 @@ int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
 
 	ret = acpi_dev_get_dma_resources(adev, &list);
 	if (ret > 0) {
+		list_for_each_entry(rentry, &list, node)
+			num_ranges++;
+
+		r = kcalloc(num_ranges + 1, sizeof(*r), GFP_KERNEL);
+		if (!r) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		*map = r;
+
 		list_for_each_entry(rentry, &list, node) {
-			if (dma_offset && rentry->offset != dma_offset) {
+			if (rentry->res->start >= rentry->res->end) {
 				ret = -EINVAL;
-				dev_warn(dma_dev, "Can't handle multiple windows with different offsets\n");
+				dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
 				goto out;
 			}
-			dma_offset = rentry->offset;
-
-			/* Take lower and upper limits */
-			if (rentry->res->start < dma_start)
-				dma_start = rentry->res->start;
-			if (rentry->res->end > dma_end)
-				dma_end = rentry->res->end;
-		}
 
-		if (dma_start >= dma_end) {
-			ret = -EINVAL;
-			dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
-			goto out;
+			r->cpu_start = rentry->res->start;
+			r->dma_start = rentry->res->start - rentry->offset;
+			r->size = rentry->res->end - rentry->res->start + 1;
+			r->offset = rentry->offset;
+			r++;
 		}
 
-		*dma_addr = dma_start - dma_offset;
-		len = dma_end - dma_start;
-		*size = max(len, len + 1);
-		*offset = dma_offset;
 	}
  out:
 	acpi_dev_free_resource_list(&list);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 0dc1ea0b..e106073 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -611,8 +611,7 @@ struct acpi_pci_root {
 int acpi_iommu_fwspec_init(struct device *dev, u32 id,
 			   struct fwnode_handle *fwnode,
 			   const struct iommu_ops *ops);
-int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
-		       u64 *size);
+int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map);
 int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
 			   const u32 *input_id);
 static inline int acpi_dma_configure(struct device *dev,
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 44975c1..f806092 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -974,8 +974,7 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
 	return DEV_DMA_NOT_SUPPORTED;
 }
 
-static inline int acpi_dma_get_range(struct device *dev, u64 *dma_addr,
-				     u64 *offset, u64 *size)
+static inline int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
 {
 	return -ENODEV;
 }
-- 
1.8.3.1