Add new bus methods for mapping resources.

Add a pair of bus methods that can be used to "map" resources for direct
CPU access using bus_space(9).  bus_map_resource() creates a mapping and
bus_unmap_resource() releases a previously created mapping.  Mappings are
described by 'struct resource_map' object.  Pointers to these objects can
be passed as the first argument to the bus_space wrapper API used for bus
resources.

Drivers that wish to map all of a resource using default settings
(for example, using uncacheable memory attributes) do not need to change.
However, drivers that wish to use non-default settings can now do so
without jumping through hoops.

First, an RF_UNMAPPED flag is added to request that a resource is not
implicitly mapped with the default settings when it is activated.  This
permits other activation steps (such as enabling I/O or memory decoding
in a device's PCI command register) to be taken without creating a
mapping.  Right now the AGP drivers don't set RF_ACTIVE to avoid using
up a large amount of KVA to map the AGP aperture on 32-bit platforms.
Once RF_UNMAPPED is supported on all platforms that support AGP this
can be changed to using RF_UNMAPPED with RF_ACTIVE instead.

Second, bus_map_resource accepts an optional structure that defines
additional settings for a given mapping.

For example, a driver can now request to map only a subset of a resource
instead of the entire range.  The AGP driver could also use this to only
map the first page of the aperture (IIRC, it calls pmap_mapdev() directly
to map the first page currently).  I will also eventually change the
PCI-PCI bridge driver to request mappings of the subset of the I/O window
resource on its parent side to create mappings for child devices rather
than passing child resources directly up to nexus to be mapped.  This
also permits bridges that do address translation to request suitable
mappings from a resource on the "upper" side of the bus when mapping
resources on the "lower" side of the bus.

Another attribute that can be specified is an alternate memory attribute
for memory-mapped resources.  This can be used to request a
Write-Combining mapping of a PCI BAR in an MI fashion.  (Currently the
drivers that do this call pmap_change_attr() directly for x86 only.)

Note that this commit only adds the MI framework.  Each platform needs
to add support for handling RF_UNMAPPED and thew new
bus_map/unmap_resource methods.  Generally speaking, any drivers that
are calling rman_set_bustag() and rman_set_bushandle() need to be
updated.

Discussed on:	arch
Reviewed by:	cem
Differential Revision:	https://reviews.freebsd.org/D5237

1 files changed, 37 insertions, 0 deletions

diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index 9b989af..4e7d375 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -294,6 +294,31 @@ struct driver {
 	KOBJ_CLASS_FIELDS;
 };
 
+/**
+ * @brief A resource mapping.
+ */
+struct resource_map {
+	bus_space_tag_t r_bustag;
+	bus_space_handle_t r_bushandle;
+	bus_size_t r_size;
+	void	*r_vaddr;
+};
+	
+/**
+ * @brief Optional properties of a resource mapping request.
+ */
+struct resource_map_request {
+	size_t	size;
+	rman_res_t offset;
+	rman_res_t length;
+	vm_memattr_t memattr;
+};
+
+void	resource_init_map_request_impl(struct resource_map_request *_args,
+	    size_t _sz);
+#define	resource_init_map_request(rmr) 					\
+	resource_init_map_request_impl((rmr), sizeof(*(rmr)))
+
 /*
  * Definitions for drivers which need to keep simple lists of resources
  * for their child devices.
@@ -407,6 +432,10 @@ bus_space_tag_t
 int	bus_generic_get_domain(device_t dev, device_t child, int *domain);
 struct resource_list *
 	bus_generic_get_resource_list (device_t, device_t);
+int	bus_generic_map_resource(device_t dev, device_t child, int type,
+				 struct resource *r,
+				 struct resource_map_request *args,
+				 struct resource_map *map);
 void	bus_generic_new_pass(device_t dev);
 int	bus_print_child_header(device_t dev, device_t child);
 int	bus_print_child_domain(device_t dev, device_t child);
@@ -440,6 +469,9 @@ int	bus_generic_suspend(device_t dev);
 int	bus_generic_suspend_child(device_t dev, device_t child);
 int	bus_generic_teardown_intr(device_t dev, device_t child,
 				  struct resource *irq, void *cookie);
+int	bus_generic_unmap_resource(device_t dev, device_t child, int type,
+				   struct resource *r,
+				   struct resource_map *map);
 int	bus_generic_write_ivar(device_t dev, device_t child, int which,
 			       uintptr_t value);
 int	bus_null_rescan(device_t dev);
@@ -469,6 +501,11 @@ int	bus_activate_resource(device_t dev, int type, int rid,
 			      struct resource *r);
 int	bus_deactivate_resource(device_t dev, int type, int rid,
 				struct resource *r);
+int	bus_map_resource(device_t dev, int type, struct resource *r,
+			 struct resource_map_request *args,
+			 struct resource_map *map);
+int	bus_unmap_resource(device_t dev, int type, struct resource *r,
+			   struct resource_map *map);
 int	bus_get_cpus(device_t dev, enum cpu_sets op, size_t setsize,
 		     struct _cpuset *cpuset);
 bus_dma_tag_t bus_get_dma_tag(device_t dev);