[PATCH v3 3/4] sh/PCI: Pass GAPSPCI_DMA_BASE CPU & bus address to dma_declare_coherent_memory()

[Bjorn Helgaas]

dma_declare_coherent_memory() needs both the CPU physical address and the
bus address of the device memory.  They are the same on this platform, but
in general we should use pcibios_resource_to_bus() to account for any
address translation done by the PCI host bridge.

This makes no difference on Dreamcast, but is safer if the usage is copied
to future drivers.

Signed-off-by: Bjorn Helgaas <bhelg...@google.com>
Acked-by: Arnd Bergmann <a...@arndb.de>
CC: Magnus Damm <d...@opensource.se>
CC: linux...@vger.kernel.org
---
 arch/sh/drivers/pci/fixups-dreamcast.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/sh/drivers/pci/fixups-dreamcast.c 
b/arch/sh/drivers/pci/fixups-dreamcast.c
index d6cde700e316..f22127f966ce 100644
--- a/arch/sh/drivers/pci/fixups-dreamcast.c
+++ b/arch/sh/drivers/pci/fixups-dreamcast.c
@@ -31,6 +31,8 @@
 static void gapspci_fixup_resources(struct pci_dev *dev)
 {
        struct pci_channel *p = dev->sysdata;
+       struct resource res;
+       struct pci_bus_region region;
 
        printk(KERN_NOTICE "PCI: Fixing up device %s\n", pci_name(dev));
 
@@ -50,11 +52,21 @@ static void gapspci_fixup_resources(struct pci_dev *dev)
 
                /*
                 * Redirect dma memory allocations to special memory window.
+                *
+                * If this GAPSPCI region were mapped by a BAR, the CPU
+                * phys_addr_t would be pci_resource_start(), and the bus
+                * address would be pci_bus_address(pci_resource_start()).
+                * But apparently there's no BAR mapping it, so we just
+                * "know" its CPU address is GAPSPCI_DMA_BASE.
                 */
+               res.start = GAPSPCI_DMA_BASE;
+               res.end = GAPSPCI_DMA_BASE + GAPSPCI_DMA_SIZE - 1;
+               res.flags = IORESOURCE_MEM;
+               pcibios_resource_to_bus(dev, &region, &resource);
                BUG_ON(!dma_declare_coherent_memory(&dev->dev,
-                                               GAPSPCI_DMA_BASE,
-                                               GAPSPCI_DMA_BASE,
-                                               GAPSPCI_DMA_SIZE,
+                                               res.start,
+                                               region.start,
+                                               resource_size(&res),
                                                DMA_MEMORY_MAP |
                                                DMA_MEMORY_EXCLUSIVE));
                break;

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