Eliminate the last dregs of the old global arm_root_dma_tag.

In the old days, device drivers passed NULL for the parent tag when creating
a new tag, and on arm platforms that resulted in a global tag representing
overall platform constraints being substituted in the busdma code.  Now all
drivers use bus_get_dma_tag() and if there is a need to represent overall
platform constraints they will be inherited from a tag supplied by nexus or
some bus driver in the hierarchy.

The only arm platforms still relying on the old global-tag scheme were some
xscale boards with special PCI-bus constraints.  This change provides those
constraints through a tag supplied by the xscale PCI bus driver, and
eliminates the few remaining references to the old global var.

Reviewed by:	cognet

4 files changed, 9 insertions, 21 deletions

diff --git a/sys/arm/arm/busdma_machdep-v6.c b/sys/arm/arm/busdma_machdep-v6.c
index d62522e..a755740 100644
--- a/sys/arm/arm/busdma_machdep-v6.c
+++ b/sys/arm/arm/busdma_machdep-v6.c
@@ -473,11 +473,6 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 	bus_dma_tag_t newtag;
 	int error = 0;
 
-#if 0
-	if (!parent)
-		parent = arm_root_dma_tag;
-#endif
-
 	/* Basic sanity checking. */
 	KASSERT(boundary == 0 || powerof2(boundary),
 	    ("dma tag boundary %lu, must be a power of 2", boundary));
diff --git a/sys/arm/arm/busdma_machdep.c b/sys/arm/arm/busdma_machdep.c
index d2f517a..f7e0e26 100644
--- a/sys/arm/arm/busdma_machdep.c
+++ b/sys/arm/arm/busdma_machdep.c
@@ -224,9 +224,6 @@ static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
 static void bus_dmamap_sync_sl(struct sync_list *sl, bus_dmasync_op_t op,
     int bufaligned);
 
-/* Default tag, as most drivers provide no parent tag. */
-bus_dma_tag_t arm_root_dma_tag;
-
 /*
  * ----------------------------------------------------------------------------
  * Begin block of code useful to transplant to other implementations.
@@ -406,8 +403,6 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 	int error = 0;
 	/* Return a NULL tag on failure */
 	*dmat = NULL;
-	if (!parent)
-		parent = arm_root_dma_tag;
 
 	newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_BUSDMA, M_NOWAIT);
 	if (newtag == NULL) {
diff --git a/sys/arm/include/bus_dma.h b/sys/arm/include/bus_dma.h
index 98803ef..ddf5504 100644
--- a/sys/arm/include/bus_dma.h
+++ b/sys/arm/include/bus_dma.h
@@ -94,8 +94,6 @@ struct arm32_dma_range {
 struct arm32_dma_range	*bus_dma_get_range(void);
 int	bus_dma_get_range_nb(void);
 
-extern bus_dma_tag_t arm_root_dma_tag;
-
 #endif /* _ARM32_BUS_DMA_PRIVATE */
 
 #endif /* _ARM_BUS_DMA_H */
diff --git a/sys/arm/xscale/ixp425/ixp425_pci.c b/sys/arm/xscale/ixp425/ixp425_pci.c
index 5a13218..9bda385 100644
--- a/sys/arm/xscale/ixp425/ixp425_pci.c
+++ b/sys/arm/xscale/ixp425/ixp425_pci.c
@@ -136,14 +136,6 @@ ixppcib_attach(device_t dev)
 	    NULL, NULL, &sc->sc_dmat))
 		panic("couldn't create the PCI dma tag !");
 	/*
-	 * The PCI bus can only address 64MB. However, due to the way our
-	 * implementation of busdma works, busdma can't tell if a device
-	 * is a PCI device or not. So defaults to the PCI dma tag, which
-	 * restrict the DMA'able memory to the first 64MB, and explicitely
-	 * create less restrictive tags for non-PCI devices.
-	 */
-	arm_root_dma_tag = sc->sc_dmat;
-	/*
 	 * Initialize the bus space tags.
 	 */
 	ixp425_io_bs_init(&sc->sc_pci_iot, sc);
@@ -361,6 +353,14 @@ ixppcib_release_resource(device_t bus, device_t child, int type, int rid,
 	return (ENXIO);
 }
 
+static bus_dma_tag_t
+ixppcib_get_dma_tag(device_t bus, device_t child)
+{
+	struct ixppcib_softc *sc = device_get_softc(bus);
+
+	return (sc->sc_dmat);
+}
+
 static void
 ixppcib_conf_setup(struct ixppcib_softc *sc, int bus, int slot, int func,
     int reg)
@@ -459,7 +459,7 @@ static device_method_t ixppcib_methods[] = {
 	DEVMETHOD(bus_activate_resource,	ixppcib_activate_resource),
 	DEVMETHOD(bus_deactivate_resource,	ixppcib_deactivate_resource),
 	DEVMETHOD(bus_release_resource,		ixppcib_release_resource),
-	/* DEVMETHOD(bus_get_dma_tag,		ixppcib_get_dma_tag), */
+	DEVMETHOD(bus_get_dma_tag,		ixppcib_get_dma_tag),
 
 	/* pcib interface */
 	DEVMETHOD(pcib_maxslots,		ixppcib_maxslots),