bus_dma_tag_create. We need to be sure that our packets are
kept in-sequence (that's how ATM is supposed to work) and
therefor use BUS_DMA_NOWAIT in all calls to bus_dmamap_load.
For memory allocated with bus_dmamem_alloc the use of anything
other than NULL arguments for the locking is anyway bogus because
this memory never should need bouncing and hence the load should never
be defered.
Allow the receipt of OAM and RM cells on raw connections. Caveat: it seems
that RM cells are still processed by the hardware even when we open the
connection as UBR.
Add two new arguments to bus_dma_tag_create(): lockfunc and lockfuncarg.
Lockfunc allows a driver to provide a function for managing its locking
semantics while using busdma. At the moment, this is used for the
asynchronous busdma_swi and callback mechanism. Two lockfunc implementations
are provided: busdma_lock_mutex() performs standard mutex operations on the
mutex that is specified from lockfuncarg. dftl_lock() is a panic
implementation and is defaulted to when NULL, NULL are passed to
bus_dma_tag_create(). The only time that NULL, NULL should ever be used is
when the driver ensures that bus_dmamap_load() will not be deferred.
Drivers that do not provide their own locking can pass
busdma_lock_mutex,&Giant args in order to preserve the former behaviour.
sparc64 and powerpc do not provide real busdma_swi functions, so this is
largely a noop on those platforms. The busdma_swi on is64 is not properly
locked yet, so warnings will be emitted on this platform when busdma
callback deferrals happen.
If anyone gets panics or warnings from dflt_lock() being called, please
let me know right away.
Reviewed by: tmm, gibbs
