xref: /freebsd/share/man/man9/bus_activate_resource.9 (revision 389e4940069316fe667ffa263fa7d6390d0a960f)
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29.\" $FreeBSD$
30.\"
31.Dd May 20, 2016
32.Dt BUS_ACTIVATE_RESOURCE 9
33.Os
34.Sh NAME
35.Nm bus_activate_resource , bus_deactivate_resource
36.Nd activate or deactivate a resource
37.Sh SYNOPSIS
38.In sys/param.h
39.In sys/bus.h
40.Pp
41.In machine/bus.h
42.In sys/rman.h
43.In machine/resource.h
44.Ft int
45.Fo bus_activate_resource
46.Fa "device_t dev" "int type" "int rid" "struct resource *r"
47.Fc
48.Ft int
49.Fo bus_deactivate_resource
50.Fa "device_t dev" "int type" "int rid" "struct resource *r"
51.Fc
52.Sh DESCRIPTION
53These functions activate or deactivate a previously allocated resource.
54In general, resources must be activated before they can be accessed by
55the driver.
56Bus drivers may perform additional actions to ensure that the resource is
57ready to be accessed.
58For example,
59the PCI bus driver enables memory decoding in a PCI device's command register
60when activating a memory resource.
61.Pp
62The arguments are as follows:
63.Bl -tag -width indent
64.It Fa dev
65The device that requests ownership of the resource.
66Before allocation, the resource is owned by the parent bus.
67.It Fa type
68The type of resource you want to allocate.
69It is one of:
70.Pp
71.Bl -tag -width ".Dv SYS_RES_MEMORY" -compact
72.It Dv PCI_RES_BUS
73for PCI bus numbers
74.It Dv SYS_RES_IRQ
75for IRQs
76.It Dv SYS_RES_DRQ
77for ISA DMA lines
78.It Dv SYS_RES_IOPORT
79for I/O ports
80.It Dv SYS_RES_MEMORY
81for I/O memory
82.El
83.It Fa rid
84A pointer to a bus specific handle that identifies the resource being allocated.
85.It Fa r
86A pointer to the
87.Vt "struct resource"
88returned by
89.Xr bus_alloc_resource 9 .
90.El
91.Ss Resource Mapping
92Resources which can be mapped for CPU access by a
93.Xr bus_space 9
94tag and handle will create a mapping of the entire resource when activated.
95The tag and handle for this mapping are stored in
96.Fa r
97and can be retrieved via
98.Xr rman_get_bustag 9
99and
100.Xr rman_get_bushandle 9 .
101These can be used with the
102.Xr bus_space 9
103API to access device registers or memory described by
104.Fa r .
105If the mapping is associated with a virtual address,
106the virtual address can be retrieved via
107.Xr rman_get_virtual 9 .
108.Pp
109This implicit mapping can be disabled by passing the
110.Dv RF_UNMAPPED
111flag to
112.Xr bus_alloc_resource 9 .
113A driver may use this if it wishes to allocate its own mappings of a resource
114using
115.Xr bus_map_resource 9 .
116.Pp
117A wrapper API for
118.Xr bus_space 9
119is also provided that accepts the associated resource as the first argument
120in place of the
121.Xr bus_space 9
122tag and handle.
123The functions in this wrapper API are named similarly to the
124.Xr bus_space 9
125API except that
126.Dq _space
127is removed from their name.
128For example,
129.Fn bus_read_4
130can be used in place of
131.Fn bus_space_read_4 .
132The wrapper API is preferred in new drivers.
133.Pp
134These two statements both read a 32-bit register at the start of a
135resource:
136.Bd -literal
137	bus_space_read_4(rman_get_bustag(res), rman_get_bushandle(res), 0);
138	bus_read_4(res, 0);
139.Ed
140.Sh RETURN VALUES
141Zero is returned on success, otherwise an error is returned.
142.Sh SEE ALSO
143.Xr bus_alloc_resource 9 ,
144.Xr bus_map_resource 9 ,
145.Xr bus_space 9 ,
146.Xr device 9 ,
147.Xr driver 9
148.Sh AUTHORS
149This manual page was written by
150.An Warner Losh Aq Mt imp@FreeBSD.org .
151