dma: Define dma_context_memory and use in sysbus-ohci

Define a new global dma_context_memory which is a DMAContext corresponding
to the global address_space_memory AddressSpace. This can be used by
sysbus peripherals like sysbus-ohci which need to do DMA.

In particular, use it in the sysbus-ohci device, which fixes a
segfault when attempting to use that device.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>

dma.h

@@ -68,6 +68,11 @@ struct DMAContext {
     DMAUnmapFunc *unmap;
 };
 
+/* A global DMA context corresponding to the address_space_memory
+ * AddressSpace, for sysbus devices which do DMA.
+ */
+extern DMAContext dma_context_memory;
+
 static inline void dma_barrier(DMAContext *dma, DMADirection dir)
 {
     /*

exec.c

@@ -34,6 +34,7 @@
 #include "hw/xen.h"
 #include "qemu-timer.h"
 #include "memory.h"
+#include "dma.h"
 #include "exec-memory.h"
 #if defined(CONFIG_USER_ONLY)
 #include <qemu.h>
@@ -103,6 +104,7 @@ static MemoryRegion *system_io;
 
 AddressSpace address_space_io;
 AddressSpace address_space_memory;
+DMAContext dma_context_memory;
 
 MemoryRegion io_mem_ram, io_mem_rom, io_mem_unassigned, io_mem_notdirty;
 static MemoryRegion io_mem_subpage_ram;
@@ -3294,6 +3296,9 @@ static void memory_map_init(void)
     memory_listener_register(&core_memory_listener, &address_space_memory);
     memory_listener_register(&io_memory_listener, &address_space_io);
     memory_listener_register(&tcg_memory_listener, &address_space_memory);
+
+    dma_context_init(&dma_context_memory, &address_space_memory,
+                     NULL, NULL, NULL);
 }
 
 MemoryRegion *get_system_memory(void)

hw/usb/hcd-ohci.c

@@ -1851,7 +1851,7 @@ static int ohci_init_pxa(SysBusDevice *dev)
 
     /* Cannot fail as we pass NULL for masterbus */
     usb_ohci_init(&s->ohci, &dev->qdev, s->num_ports, s->dma_offset, NULL, 0,
-                  NULL);
+                  &dma_context_memory);
     sysbus_init_irq(dev, &s->ohci.irq);
     sysbus_init_mmio(dev, &s->ohci.mem);