From: Jim Quinlan <james.quin...@broadcom.com>

The new field 'dma_range_map' in struct device is used to facilitate the
use of single or multiple offsets between mapping regions of cpu addrs and
dma addrs.  It subsumes the role of "dev->dma_pfn_offset" which was only
capable of holding a single uniform offset and had no region bounds
checking.

The function of_dma_get_range() has been modified so that it takes a single
argument -- the device node -- and returns a map, NULL, or an error code.
The map is an array that holds the information regarding the DMA regions.
Each range entry contains the address offset, the cpu_start address, the
dma_start address, and the size of the region.

of_dma_configure() is the typical manner to set range offsets but there are
a number of ad hoc assignments to "dev->dma_pfn_offset" in the kernel
driver code.  These cases now invoke the function
dma_attach_offset_range(dev, cpu_addr, dma_addr, size).

Signed-off-by: Jim Quinlan <james.quin...@broadcom.com>
[hch: various interface cleanups]
Signed-off-by: Christoph Hellwig <h...@lst.de>
Tested-by: Nathan Chancellor <natechancel...@gmail.com>
---
 arch/arm/include/asm/dma-direct.h             |  9 +--
 arch/arm/mach-keystone/keystone.c             | 17 ++--
 arch/sh/drivers/pci/pcie-sh7786.c             |  9 ++-
 arch/x86/pci/sta2x11-fixup.c                  |  6 +-
 drivers/acpi/arm64/iort.c                     |  6 +-
 drivers/base/core.c                           |  2 +
 drivers/gpu/drm/sun4i/sun4i_backend.c         |  8 +-
 drivers/iommu/io-pgtable-arm.c                |  2 +-
 .../platform/sunxi/sun4i-csi/sun4i_csi.c      |  9 ++-
 .../platform/sunxi/sun6i-csi/sun6i_csi.c      | 11 ++-
 drivers/of/address.c                          | 73 ++++++++---------
 drivers/of/device.c                           | 44 ++++++----
 drivers/of/of_private.h                       | 11 +--
 drivers/of/unittest.c                         | 34 +++++---
 drivers/remoteproc/remoteproc_core.c          |  4 +-
 .../staging/media/sunxi/cedrus/cedrus_hw.c    | 10 ++-
 drivers/usb/core/message.c                    |  5 +-
 drivers/usb/core/usb.c                        |  3 +-
 include/linux/device.h                        |  4 +-
 include/linux/dma-direct.h                    | 52 ++++++++++--
 include/linux/dma-mapping.h                   | 19 ++++-
 kernel/dma/coherent.c                         |  7 +-
 kernel/dma/direct.c                           | 81 ++++++++++++++++++-
 23 files changed, 303 insertions(+), 123 deletions(-)

diff --git a/arch/arm/include/asm/dma-direct.h 
b/arch/arm/include/asm/dma-direct.h
index de0f4ff9279615..a443d5257a21ed 100644
--- a/arch/arm/include/asm/dma-direct.h
+++ b/arch/arm/include/asm/dma-direct.h
@@ -16,8 +16,8 @@
 #ifndef __arch_pfn_to_dma
 static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
 {
-       if (dev)
-               pfn -= dev->dma_pfn_offset;
+       if (dev && dev->dma_range_map)
+               pfn = PFN_DOWN(translate_phys_to_dma(dev, PFN_PHYS(pfn)));
        return (dma_addr_t)__pfn_to_bus(pfn);
 }
 
@@ -25,9 +25,8 @@ static inline unsigned long dma_to_pfn(struct device *dev, 
dma_addr_t addr)
 {
        unsigned long pfn = __bus_to_pfn(addr);
 
-       if (dev)
-               pfn += dev->dma_pfn_offset;
-
+       if (dev && dev->dma_range_map)
+               pfn = PFN_DOWN(translate_dma_to_phys(dev, PFN_PHYS(pfn)));
        return pfn;
 }
 
diff --git a/arch/arm/mach-keystone/keystone.c 
b/arch/arm/mach-keystone/keystone.c
index dcd031ba84c2e0..09a65c2dfd7327 100644
--- a/arch/arm/mach-keystone/keystone.c
+++ b/arch/arm/mach-keystone/keystone.c
@@ -8,6 +8,7 @@
  */
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/dma-mapping.h>
 #include <linux/init.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
@@ -25,8 +26,6 @@
 #include "keystone.h"
 
 #ifdef CONFIG_ARM_LPAE
-static unsigned long keystone_dma_pfn_offset __read_mostly;
-
 static int keystone_platform_notifier(struct notifier_block *nb,
                                      unsigned long event, void *data)
 {
@@ -39,9 +38,12 @@ static int keystone_platform_notifier(struct notifier_block 
*nb,
                return NOTIFY_BAD;
 
        if (!dev->of_node) {
-               dev->dma_pfn_offset = keystone_dma_pfn_offset;
-               dev_err(dev, "set dma_pfn_offset%08lx\n",
-                       dev->dma_pfn_offset);
+               int ret = dma_direct_set_offset(dev, KEYSTONE_HIGH_PHYS_START,
+                                               KEYSTONE_LOW_PHYS_START,
+                                               KEYSTONE_HIGH_PHYS_SIZE);
+               dev_err(dev, "set dma_offset%08llx%s\n",
+                       KEYSTONE_HIGH_PHYS_START - KEYSTONE_LOW_PHYS_START,
+                       ret ? " failed" : "");
        }
        return NOTIFY_OK;
 }
@@ -54,11 +56,8 @@ static struct notifier_block platform_nb = {
 static void __init keystone_init(void)
 {
 #ifdef CONFIG_ARM_LPAE
-       if (PHYS_OFFSET >= KEYSTONE_HIGH_PHYS_START) {
-               keystone_dma_pfn_offset = PFN_DOWN(KEYSTONE_HIGH_PHYS_START -
-                                                  KEYSTONE_LOW_PHYS_START);
+       if (PHYS_OFFSET >= KEYSTONE_HIGH_PHYS_START)
                bus_register_notifier(&platform_bus_type, &platform_nb);
-       }
 #endif
        keystone_pm_runtime_init();
 }
diff --git a/arch/sh/drivers/pci/pcie-sh7786.c 
b/arch/sh/drivers/pci/pcie-sh7786.c
index e0b568aaa7014c..4468289ab2cac7 100644
--- a/arch/sh/drivers/pci/pcie-sh7786.c
+++ b/arch/sh/drivers/pci/pcie-sh7786.c
@@ -12,6 +12,7 @@
 #include <linux/io.h>
 #include <linux/async.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/clk.h>
 #include <linux/sh_clk.h>
@@ -31,6 +32,8 @@ struct sh7786_pcie_port {
 static struct sh7786_pcie_port *sh7786_pcie_ports;
 static unsigned int nr_ports;
 static unsigned long dma_pfn_offset;
+size_t memsize;
+u64 memstart;
 
 static struct sh7786_pcie_hwops {
        int (*core_init)(void);
@@ -301,7 +304,6 @@ static int __init pcie_init(struct sh7786_pcie_port *port)
        struct pci_channel *chan = port->hose;
        unsigned int data;
        phys_addr_t memstart, memend;
-       size_t memsize;
        int ret, i, win;
 
        /* Begin initialization */
@@ -368,8 +370,6 @@ static int __init pcie_init(struct sh7786_pcie_port *port)
        memstart = ALIGN_DOWN(memstart, memsize);
        memsize = roundup_pow_of_two(memend - memstart);
 
-       dma_pfn_offset = memstart >> PAGE_SHIFT;
-
        /*
         * If there's more than 512MB of memory, we need to roll over to
         * LAR1/LAMR1.
@@ -487,7 +487,8 @@ int pcibios_map_platform_irq(const struct pci_dev *pdev, u8 
slot, u8 pin)
 
 void pcibios_bus_add_device(struct pci_dev *pdev)
 {
-       pdev->dev.dma_pfn_offset = dma_pfn_offset;
+       dma_direct_set_offset(&pdev->dev, __pa(memory_start),
+                             __pa(memory_start) - memstart, memsize);
 }
 
 static int __init sh7786_pcie_core_init(void)
diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
index c313d784efabb9..324a207f99956b 100644
--- a/arch/x86/pci/sta2x11-fixup.c
+++ b/arch/x86/pci/sta2x11-fixup.c
@@ -133,7 +133,7 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
        struct sta2x11_instance *instance = sta2x11_pdev_to_instance(pdev);
        struct device *dev = &pdev->dev;
        u32 amba_base, max_amba_addr;
-       int i;
+       int i, ret;
 
        if (!instance)
                return;
@@ -141,7 +141,9 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
        pci_read_config_dword(pdev, AHB_BASE(0), &amba_base);
        max_amba_addr = amba_base + STA2X11_AMBA_SIZE - 1;
 
-       dev->dma_pfn_offset = PFN_DOWN(-amba_base);
+       ret = dma_direct_set_offset(dev, 0, amba_base, STA2X11_AMBA_SIZE);
+       if (ret)
+               dev_err(dev, "sta2x11: could not set DMA offset\n");
 
        dev->bus_dma_limit = max_amba_addr;
        pci_set_consistent_dma_mask(pdev, max_amba_addr);
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index ec782e4a0fe419..de18c07ca02cc4 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -18,6 +18,7 @@
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/dma-mapping.h>
 
 #define IORT_TYPE_MASK(type)   (1 << (type))
 #define IORT_MSI_TYPE          (1 << ACPI_IORT_NODE_ITS_GROUP)
@@ -1184,8 +1185,9 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, 
u64 *dma_size)
        *dma_addr = dmaaddr;
        *dma_size = size;
 
-       dev->dma_pfn_offset = PFN_DOWN(offset);
-       dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
+       ret = dma_direct_set_offset(dev, dmaaddr + offset, dmaaddr, size);
+
+       dev_dbg(dev, "dma_offset(%#08llx)%s\n", offset, ret ? " failed!" : "");
 }
 
 static void __init acpi_iort_register_irq(int hwirq, const char *name,
diff --git a/drivers/base/core.c b/drivers/base/core.c
index f6f620aa94086d..b893056e39459c 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1792,6 +1792,8 @@ static void device_release(struct kobject *kobj)
         */
        devres_release_all(dev);
 
+       kfree(dev->dma_range_map);
+
        if (dev->release)
                dev->release(dev);
        else if (dev->type && dev->type->release)
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c 
b/drivers/gpu/drm/sun4i/sun4i_backend.c
index 072ea113e6be55..05e9f0d28196d9 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/of_graph.h>
+#include <linux/dma-mapping.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 
@@ -811,8 +812,13 @@ static int sun4i_backend_bind(struct device *dev, struct 
device *master,
                 * because of an old DT, we need to set the DMA offset by hand
                 * on our device since the RAM mapping is at 0 for the DMA bus,
                 * unlike the CPU.
+                *
+                * XXX(hch): this has no business in a driver and needs to move
+                * to the device tree.
                 */
-               drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+               ret = dma_direct_set_offset(drm->dev, PHYS_OFFSET, 0, SZ_4G);
+               if (ret)
+                       return ret;
        }
 
        backend->engine.node = dev->of_node;
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index dc7bcf858b6d2d..d77e881516a4ab 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -751,7 +751,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
        if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
                return NULL;
 
-       if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
+       if (!selftest_running && cfg->iommu_dev->dma_range_map) {
                dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for 
IOMMU page tables\n");
                return NULL;
        }
diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c 
b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
index 5319eb1ab30927..307997ee7f96a2 100644
--- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
+++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -182,8 +183,14 @@ static int sun4i_csi_probe(struct platform_device *pdev)
                if (ret)
                        return ret;
        } else {
+               /*
+                * XXX(hch): this has no business in a driver and needs to move
+                * to the device tree.
+                */
 #ifdef PHYS_PFN_OFFSET
-               csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+               ret = dma_direct_set_offset(csi->dev, PHYS_OFFSET, 0, SZ_4G);
+               if (ret)
+                       return ret;
 #endif
        }
 
diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c 
b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
index 28e89340fed981..e69e14379fc6e4 100644
--- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
+++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
@@ -899,8 +899,15 @@ static int sun6i_csi_probe(struct platform_device *pdev)
                return -ENOMEM;
 
        sdev->dev = &pdev->dev;
-       /* The DMA bus has the memory mapped at 0 */
-       sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
+       /*
+        * The DMA bus has the memory mapped at 0.
+        *
+        * XXX(hch): this has no business in a driver and needs to move
+        * to the device tree.
+        */
+       ret = dma_direct_set_offset(sdev->dev, PHYS_OFFSET, 0, SZ_4G);
+       if (ret)
+               return ret;
 
        ret = sun6i_csi_resource_request(sdev, pdev);
        if (ret)
diff --git a/drivers/of/address.c b/drivers/of/address.c
index da4f7341323f22..a49ef87aaaf21c 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -13,6 +13,7 @@
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/dma-direct.h> /* for bus_dma_region */
 
 #include "of_private.h"
 
@@ -937,33 +938,33 @@ void __iomem *of_io_request_and_map(struct device_node 
*np, int index,
 }
 EXPORT_SYMBOL(of_io_request_and_map);
 
+#ifdef CONFIG_HAS_DMA
 /**
- * of_dma_get_range - Get DMA range info
+ * of_dma_get_range - Get DMA range info and put it into a map array
  * @np:                device node to get DMA range info
- * @dma_addr:  pointer to store initial DMA address of DMA range
- * @paddr:     pointer to store initial CPU address of DMA range
- * @size:      pointer to store size of DMA range
+ * @map:       dma range structure to return
  *
  * Look in bottom up direction for the first "dma-ranges" property
- * and parse it.
- *  dma-ranges format:
+ * and parse it.  Put the information into a DMA offset map array.
+ *
+ * dma-ranges format:
  *     DMA addr (dma_addr)     : naddr cells
  *     CPU addr (phys_addr_t)  : pna cells
  *     size                    : nsize cells
  *
- * It returns -ENODEV if "dma-ranges" property was not found
- * for this device in DT.
+ * It returns -ENODEV if "dma-ranges" property was not found for this
+ * device in the DT.
  */
-int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 
*size)
+int of_dma_get_range(struct device_node *np, const struct bus_dma_region **map)
 {
        struct device_node *node = of_node_get(np);
        const __be32 *ranges = NULL;
-       int len;
-       int ret = 0;
        bool found_dma_ranges = false;
        struct of_range_parser parser;
        struct of_range range;
-       u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
+       struct bus_dma_region *r;
+       int len, num_ranges = 0;
+       int ret = 0;
 
        while (node) {
                ranges = of_get_property(node, "dma-ranges", &len);
@@ -989,49 +990,39 @@ int of_dma_get_range(struct device_node *np, u64 
*dma_addr, u64 *paddr, u64 *siz
        }
 
        of_dma_range_parser_init(&parser, node);
+       for_each_of_range(&parser, &range)
+               num_ranges++;
+
+       r = kcalloc(num_ranges + 1, sizeof(*r), GFP_KERNEL);
+       if (!r) {
+               ret = -ENOMEM;
+               goto out;
+       }
 
+       /*
+        * Record all info in the generic DMA ranges array for struct device.
+        */
+       *map = r;
+       of_dma_range_parser_init(&parser, node);
        for_each_of_range(&parser, &range) {
                pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
                         range.bus_addr, range.cpu_addr, range.size);
-
-               if (dma_offset && range.cpu_addr - range.bus_addr != 
dma_offset) {
-                       pr_warn("Can't handle multiple dma-ranges with 
different offsets on node(%pOF)\n", node);
-                       /* Don't error out as we'd break some existing DTs */
-                       continue;
-               }
                if (range.cpu_addr == OF_BAD_ADDR) {
                        pr_err("translation of DMA address(%llx) to CPU address 
failed node(%pOF)\n",
                               range.bus_addr, node);
                        continue;
                }
-               dma_offset = range.cpu_addr - range.bus_addr;
-
-               /* Take lower and upper limits */
-               if (range.bus_addr < dma_start)
-                       dma_start = range.bus_addr;
-               if (range.bus_addr + range.size > dma_end)
-                       dma_end = range.bus_addr + range.size;
-       }
-
-       if (dma_start >= dma_end) {
-               ret = -EINVAL;
-               pr_debug("Invalid DMA ranges configuration on node(%pOF)\n",
-                        node);
-               goto out;
+               r->cpu_start = range.cpu_addr;
+               r->dma_start = range.bus_addr;
+               r->size = range.size;
+               r->offset = range.cpu_addr - range.bus_addr;
+               r++;
        }
-
-       *dma_addr = dma_start;
-       *size = dma_end - dma_start;
-       *paddr = dma_start + dma_offset;
-
-       pr_debug("final: dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
-                *dma_addr, *paddr, *size);
-
 out:
        of_node_put(node);
-
        return ret;
 }
+#endif /* CONFIG_HAS_DMA */
 
 /**
  * of_dma_is_coherent - Check if device is coherent
diff --git a/drivers/of/device.c b/drivers/of/device.c
index b439c1e054349b..6e3ae7ebc33eeb 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -5,7 +5,7 @@
 #include <linux/of_device.h>
 #include <linux/of_address.h>
 #include <linux/of_iommu.h>
-#include <linux/dma-mapping.h>
+#include <linux/dma-direct.h> /* for bus_dma_region */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
@@ -90,14 +90,14 @@ int of_device_add(struct platform_device *ofdev)
 int of_dma_configure_id(struct device *dev, struct device_node *np,
                        bool force_dma, const u32 *id)
 {
-       u64 dma_addr, paddr, size = 0;
-       int ret;
-       bool coherent;
-       unsigned long offset;
        const struct iommu_ops *iommu;
-       u64 mask, end;
+       const struct bus_dma_region *map = NULL;
+       dma_addr_t dma_start = 0;
+       u64 mask, end, size = 0;
+       bool coherent;
+       int ret;
 
-       ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
+       ret = of_dma_get_range(np, &map);
        if (ret < 0) {
                /*
                 * For legacy reasons, we have to assume some devices need
@@ -106,26 +106,35 @@ int of_dma_configure_id(struct device *dev, struct 
device_node *np,
                 */
                if (!force_dma)
                        return ret == -ENODEV ? 0 : ret;
-
-               dma_addr = offset = 0;
        } else {
-               offset = PFN_DOWN(paddr - dma_addr);
+               const struct bus_dma_region *r = map;
+               dma_addr_t dma_end = 0;
+
+               /* Determine the overall bounds of all DMA regions */
+               for (dma_start = ~(dma_addr_t)0; r->size; r++) {
+                       /* Take lower and upper limits */
+                       if (r->dma_start < dma_start)
+                               dma_start = r->dma_start;
+                       if (r->dma_start + r->size > dma_end)
+                               dma_end = r->dma_start + r->size;
+               }
+               size = dma_end - dma_start;
 
                /*
                 * Add a work around to treat the size as mask + 1 in case
                 * it is defined in DT as a mask.
                 */
                if (size & 1) {
-                       dev_warn(dev, "Invalid size 0x%llx for dma-range\n",
+                       dev_warn(dev, "Invalid size 0x%llx for dma-range(s)\n",
                                 size);
                        size = size + 1;
                }
 
                if (!size) {
                        dev_err(dev, "Adjusted size 0x%llx invalid\n", size);
+                       kfree(map);
                        return -EINVAL;
                }
-               dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
        }
 
        /*
@@ -144,13 +153,11 @@ int of_dma_configure_id(struct device *dev, struct 
device_node *np,
        else if (!size)
                size = 1ULL << 32;
 
-       dev->dma_pfn_offset = offset;
-
        /*
         * Limit coherent and dma mask based on size and default mask
         * set by the driver.
         */
-       end = dma_addr + size - 1;
+       end = dma_start + size - 1;
        mask = DMA_BIT_MASK(ilog2(end) + 1);
        dev->coherent_dma_mask &= mask;
        *dev->dma_mask &= mask;
@@ -163,14 +170,17 @@ int of_dma_configure_id(struct device *dev, struct 
device_node *np,
                coherent ? " " : " not ");
 
        iommu = of_iommu_configure(dev, np, id);
-       if (PTR_ERR(iommu) == -EPROBE_DEFER)
+       if (PTR_ERR(iommu) == -EPROBE_DEFER) {
+               kfree(map);
                return -EPROBE_DEFER;
+       }
 
        dev_dbg(dev, "device is%sbehind an iommu\n",
                iommu ? " " : " not ");
 
-       arch_setup_dma_ops(dev, dma_addr, size, iommu, coherent);
+       arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
 
+       dev->dma_range_map = map;
        return 0;
 }
 EXPORT_SYMBOL_GPL(of_dma_configure_id);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index edc682249c0015..d9e6a324de0a77 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -157,12 +157,13 @@ extern void __of_sysfs_remove_bin_file(struct device_node 
*np,
 extern int of_bus_n_addr_cells(struct device_node *np);
 extern int of_bus_n_size_cells(struct device_node *np);
 
-#ifdef CONFIG_OF_ADDRESS
-extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
-                           u64 *paddr, u64 *size);
+struct bus_dma_region;
+#if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
+int of_dma_get_range(struct device_node *np,
+               const struct bus_dma_region **map);
 #else
-static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
-                                  u64 *paddr, u64 *size)
+static inline int of_dma_get_range(struct device_node *np,
+               const struct bus_dma_region **map)
 {
        return -ENODEV;
 }
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 9b7e84bdc7d446..06cc988faf78b3 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -7,6 +7,7 @@
 
 #include <linux/memblock.h>
 #include <linux/clk.h>
+#include <linux/dma-direct.h> /* to test phys_to_dma/dma_to_phys */
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/hashtable.h>
@@ -869,10 +870,11 @@ static void __init of_unittest_changeset(void)
 }
 
 static void __init of_unittest_dma_ranges_one(const char *path,
-               u64 expect_dma_addr, u64 expect_paddr, u64 expect_size)
+               u64 expect_dma_addr, u64 expect_paddr)
 {
+#ifdef CONFIG_HAS_DMA
        struct device_node *np;
-       u64 dma_addr, paddr, size;
+       const struct bus_dma_region *map = NULL;
        int rc;
 
        np = of_find_node_by_path(path);
@@ -881,28 +883,40 @@ static void __init of_unittest_dma_ranges_one(const char 
*path,
                return;
        }
 
-       rc = of_dma_get_range(np, &dma_addr, &paddr, &size);
+       rc = of_dma_get_range(np, &map);
 
        unittest(!rc, "of_dma_get_range failed on node %pOF rc=%i\n", np, rc);
+
        if (!rc) {
-               unittest(size == expect_size,
-                        "of_dma_get_range wrong size on node %pOF 
size=%llx\n", np, size);
+               phys_addr_t     paddr;
+               dma_addr_t      dma_addr;
+               struct device   dev_bogus;
+
+               dev_bogus.dma_range_map = map;
+               paddr = dma_to_phys(&dev_bogus, expect_dma_addr);
+               dma_addr = phys_to_dma(&dev_bogus, expect_paddr);
+
                unittest(paddr == expect_paddr,
-                        "of_dma_get_range wrong phys addr (%llx) on node 
%pOF", paddr, np);
+                        "of_dma_get_range: wrong phys addr %pap (expecting 
%llx) on node %pOF\n",
+                        &paddr, expect_paddr, np);
                unittest(dma_addr == expect_dma_addr,
-                        "of_dma_get_range wrong DMA addr (%llx) on node %pOF", 
dma_addr, np);
+                        "of_dma_get_range: wrong DMA addr %pad (expecting 
%llx) on node %pOF\n",
+                        &dma_addr, expect_dma_addr, np);
+
+               kfree(map);
        }
        of_node_put(np);
+#endif
 }
 
 static void __init of_unittest_parse_dma_ranges(void)
 {
        
of_unittest_dma_ranges_one("/testcase-data/address-tests/device@70000000",
-               0x0, 0x20000000, 0x40000000);
+               0x0, 0x20000000);
        
of_unittest_dma_ranges_one("/testcase-data/address-tests/bus@80000000/device@1000",
-               0x100000000, 0x20000000, 0x2000000000);
+               0x100000000, 0x20000000);
        of_unittest_dma_ranges_one("/testcase-data/address-tests/pci@90000000",
-               0x80000000, 0x20000000, 0x10000000);
+               0x80000000, 0x20000000);
 }
 
 static void __init of_unittest_pci_dma_ranges(void)
diff --git a/drivers/remoteproc/remoteproc_core.c 
b/drivers/remoteproc/remoteproc_core.c
index 7f90eeea67e279..bc412fb164a3fe 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -529,7 +529,9 @@ static int rproc_handle_vdev(struct rproc *rproc, struct 
fw_rsc_vdev *rsc,
        /* Initialise vdev subdevice */
        snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
        rvdev->dev.parent = &rproc->dev;
-       rvdev->dev.dma_pfn_offset = rproc->dev.parent->dma_pfn_offset;
+       ret = dma_direct_copy_range_map(&rvdev->dev, rproc->dev.parent);
+       if (ret)
+               return ret;
        rvdev->dev.release = rproc_rvdev_release;
        dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
        dev_set_drvdata(&rvdev->dev, rvdev);
diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c 
b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
index 1744e6fcc99980..bcf050a04ffc45 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
@@ -227,11 +227,17 @@ int cedrus_hw_probe(struct cedrus_dev *dev)
         * the RAM offset to the physcal addresses.
         *
         * This information will eventually be obtained from device-tree.
+        *
+        * XXX(hch): this has no business in a driver and needs to move
+        * to the device tree.
         */
 
 #ifdef PHYS_PFN_OFFSET
-       if (!(variant->quirks & CEDRUS_QUIRK_NO_DMA_OFFSET))
-               dev->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+       if (!(variant->quirks & CEDRUS_QUIRK_NO_DMA_OFFSET)) {
+               ret = dma_direct_set_offset(dev->dev, PHYS_OFFSET, 0, SZ_4G);
+               if (ret)
+                       return ret;
+       }
 #endif
 
        ret = of_reserved_mem_device_init(dev->dev);
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 6197938dcc2d8f..935ee98e049f65 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1956,10 +1956,11 @@ int usb_set_configuration(struct usb_device *dev, int 
configuration)
                intf->dev.groups = usb_interface_groups;
                /*
                 * Please refer to usb_alloc_dev() to see why we set
-                * dma_mask and dma_pfn_offset.
+                * dma_mask and dma_range_map.
                 */
                intf->dev.dma_mask = dev->dev.dma_mask;
-               intf->dev.dma_pfn_offset = dev->dev.dma_pfn_offset;
+               if (dma_direct_copy_range_map(&intf->dev, &dev->dev))
+                       dev_err(&dev->dev, "failed to copy DMA map\n");
                INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
                intf->minor = -1;
                device_initialize(&intf->dev);
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index bafc113f2b3ef3..23d451f6894d70 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -610,7 +610,8 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
         * mask for the entire HCD, so don't do that.
         */
        dev->dev.dma_mask = bus->sysdev->dma_mask;
-       dev->dev.dma_pfn_offset = bus->sysdev->dma_pfn_offset;
+       if (dma_direct_copy_range_map(&dev->dev, bus->sysdev))
+               dev_err(&dev->dev, "failed to copy DMA map\n");
        set_dev_node(&dev->dev, dev_to_node(bus->sysdev));
        dev->state = USB_STATE_ATTACHED;
        dev->lpm_disable_count = 1;
diff --git a/include/linux/device.h b/include/linux/device.h
index ca18da4768e3e8..1c78621fc3c01f 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -466,7 +466,7 @@ struct dev_links_info {
  *             such descriptors.
  * @bus_dma_limit: Limit of an upstream bridge or bus which imposes a smaller
  *             DMA limit than the device itself supports.
- * @dma_pfn_offset: offset of DMA memory range relatively of RAM
+ * @dma_range_map: map for DMA memory ranges relative to that of RAM
  * @dma_parms: A low level driver may set these to teach IOMMU code about
  *             segment limitations.
  * @dma_pools: Dma pools (if dma'ble device).
@@ -561,7 +561,7 @@ struct device {
                                             64 bit addresses for consistent
                                             allocations such descriptors. */
        u64             bus_dma_limit;  /* upstream dma constraint */
-       unsigned long   dma_pfn_offset;
+       const struct bus_dma_region *dma_range_map;
 
        struct device_dma_parameters *dma_parms;
 
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 6e87225600ae35..715dcb7d64d5a4 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -14,21 +14,56 @@
 
 extern unsigned int zone_dma_bits;
 
+/*
+ * Record the mapping of CPU physical to DMA addresses for a given region.
+ */
+struct bus_dma_region {
+       phys_addr_t     cpu_start;
+       dma_addr_t      dma_start;
+       u64             size;
+       u64             offset;
+};
+
+static inline dma_addr_t translate_phys_to_dma(struct device *dev,
+               phys_addr_t paddr)
+{
+       const struct bus_dma_region *m;
+
+       for (m = dev->dma_range_map; m->size; m++)
+               if (paddr >= m->cpu_start && paddr - m->cpu_start < m->size)
+                       return (dma_addr_t)paddr - m->offset;
+
+       /* make sure dma_capable fails when no translation is available */
+       return DMA_MAPPING_ERROR; 
+}
+
+static inline phys_addr_t translate_dma_to_phys(struct device *dev,
+               dma_addr_t dma_addr)
+{
+       const struct bus_dma_region *m;
+
+       for (m = dev->dma_range_map; m->size; m++)
+               if (dma_addr >= m->dma_start && dma_addr - m->dma_start < 
m->size)
+                       return (phys_addr_t)dma_addr + m->offset;
+
+       return 0;
+}
+
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #else
 static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
-       dma_addr_t dev_addr = (dma_addr_t)paddr;
-
-       return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+       if (dev->dma_range_map)
+               return translate_phys_to_dma(dev, paddr);
+       return paddr;
 }
 
-static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t 
dev_addr)
+static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t 
dma_addr)
 {
-       phys_addr_t paddr = (phys_addr_t)dev_addr;
-
-       return paddr + ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+       if (dev->dma_range_map)
+               return translate_dma_to_phys(dev, dma_addr);
+       return dma_addr;
 }
 #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
 
@@ -64,7 +99,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t 
addr, size_t size,
 
        if (!dev->dma_mask)
                return false;
-
+       if (addr == DMA_MAPPING_ERROR)
+               return false;
        if (is_ram && !IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) &&
            min(addr, end) < phys_to_dma(dev, PFN_PHYS(min_low_pfn)))
                return false;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index df0bff2ea750e0..e8fcb19c9112f8 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -730,4 +730,21 @@ static inline int dma_mmap_wc(struct device *dev,
 #define dma_unmap_len_set(PTR, LEN_NAME, VAL)    do { } while (0)
 #endif
 
-#endif
+/*
+ * These interfaces deal with the offset ranges for the direct mapping.
+ * Drivers really should not use them, but we have a few legacy cases
+ * that need them left.
+ */
+int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start,
+               dma_addr_t dma_start, u64 size);
+#ifdef CONFIG_HAS_DMA
+int dma_direct_copy_range_map(struct device *to, struct device *from);
+#else
+static inline int dma_direct_copy_range_map(struct device *to,
+               struct device *from)
+{
+       return 0;
+}
+#endif /* CONFIG_HAS_DMA */
+
+#endif /* _LINUX_DMA_MAPPING_H */
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 2a0c4985f38e41..029fdc3eb670ae 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -7,7 +7,7 @@
 #include <linux/slab.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/dma-mapping.h>
+#include <linux/dma-direct.h>
 
 struct dma_coherent_mem {
        void            *virt_base;
@@ -32,9 +32,8 @@ static inline dma_addr_t dma_get_device_base(struct device 
*dev,
                                             struct dma_coherent_mem * mem)
 {
        if (mem->use_dev_dma_pfn_offset)
-               return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
-       else
-               return mem->device_base;
+               return phys_to_dma(dev, PFN_PHYS(mem->pfn_base));
+       return mem->device_base;
 }
 
 static int dma_init_coherent_memory(phys_addr_t phys_addr,
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index db6ef07aec3b37..fc815f7375e282 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -13,6 +13,7 @@
 #include <linux/pfn.h>
 #include <linux/vmalloc.h>
 #include <linux/set_memory.h>
+#include <linux/slab.h>
 
 /*
  * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
@@ -70,8 +71,12 @@ static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, 
u64 dma_mask,
 
 static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
 {
-       return phys_to_dma_direct(dev, phys) + size - 1 <=
-                       min_not_zero(dev->coherent_dma_mask, 
dev->bus_dma_limit);
+       dma_addr_t dma_addr = phys_to_dma_direct(dev, phys);
+
+       if (dma_addr == DMA_MAPPING_ERROR)
+               return false;
+       return dma_addr + size - 1 <=
+               min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
 }
 
 /*
@@ -476,3 +481,75 @@ bool dma_direct_need_sync(struct device *dev, dma_addr_t 
dma_addr)
        return !dev_is_dma_coherent(dev) ||
                is_swiotlb_buffer(dma_to_phys(dev, dma_addr));
 }
+
+/**
+ * dma_direct_set_offset - Assign scalar offset for a single DMA range.
+ * @dev:       device pointer; needed to "own" the alloced memory.
+ * @cpu_start:  beginning of memory region covered by this offset.
+ * @dma_start:  beginning of DMA/PCI region covered by this offset.
+ * @size:      size of the region.
+ *
+ * This is for the simple case of a uniform offset which cannot
+ * be discovered by "dma-ranges".
+ *
+ * It returns -ENOMEM if out of memory, -EINVAL if a map
+ * already exists, 0 otherwise.
+ *
+ * Note: any call to this from a driver is a bug.  The mapping needs
+ * to be described by the device tree or other firmware interfaces.
+ */
+int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start,
+                        dma_addr_t dma_start, u64 size)
+{
+       struct bus_dma_region *map;
+       u64 offset = (u64)cpu_start - (u64)dma_start;
+
+       if (dev->dma_range_map) {
+               dev_err(dev, "attempt to add DMA range to existing map\n");
+               return -EINVAL;
+       }
+
+       if (!offset)
+               return 0;
+
+       map = kcalloc(2, sizeof(*map), GFP_KERNEL);
+       if (!map)
+               return -ENOMEM;
+       map[0].cpu_start = cpu_start;
+       map[0].dma_start = dma_start;
+       map[0].offset = offset;
+       map[0].size = size;
+       dev->dma_range_map = map;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(dma_direct_set_offset);
+
+/**
+ * dma_direct_copy_range_map - Copy the dma_range from one device to another
+ * @to:                device to copy to
+ * @from:      device to copy from
+ *
+ * Note: this should not be used in any new code.  Drivers should never try
+ * to inherit DMA parameters from other devices but just use those other
+ * devices in the DMA mapping functions.
+ */
+int dma_direct_copy_range_map(struct device *to, struct device *from)
+{
+       const struct bus_dma_region *map = from->dma_range_map, *new_map, *r;
+       int num_ranges = 0;
+
+       if (!map)
+               return 0;
+
+       for (r = map; r->size; r++)
+               num_ranges++;
+
+       new_map = kmemdup(map, array_size(num_ranges + 1, sizeof(*map)),
+                         GFP_KERNEL);
+       if (!new_map)
+               return -ENOMEM;
+       to->dma_range_map = new_map;
+       return 0;
+}
+EXPORT_SYMBOL_GPL(dma_direct_copy_range_map);
-- 
2.28.0

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