freebsd-dev/sys/i4b
Scott Long f6b1c44d1f Mega busdma API commit.
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
2003-07-01 15:52:06 +00:00
..
capi Use __FBSDID(). 2003-06-10 23:23:33 +00:00
driver Use __FBSDID(). 2003-06-10 23:23:33 +00:00
include
layer1 Mega busdma API commit. 2003-07-01 15:52:06 +00:00
layer2 Use __FBSDID(). 2003-06-11 00:01:05 +00:00
layer3 Use __FBSDID(). 2003-06-11 00:01:05 +00:00
layer4 Use __FBSDID(). 2003-06-11 00:01:05 +00:00