xref: /freebsd/share/man/man9/bus_alloc_resource.9 (revision 77a0943ded95b9e6438f7db70c4a28e4d93946d4)
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29.\" $FreeBSD$
30.\"
31.Dd May 18, 2000
32.Dt BUS_ALLOC_RESOURCE 9
33.Os FreeBSD
34.Sh NAME
35.Nm bus_alloc_resource
36.Nd alloc resources on a bus
37.Sh SYNOPSIS
38.Fd #include <sys/param.h>
39.Fd #include <sys/bus.h>
40.Fd #include <sys/rman.h>
41.Fd #include <sys/resource.h>
42.Ft struct resource *
43.Fn bus_alloc_resource "device_t dev" "int type" "int *rid" "u_long start" "u_long end" "u_long count" "u_int flags"
44.Sh DESCRIPTION
45.Pp
46This is an easy interface to the resource-management functions.
47It hides the indirection through the parent's method table.
48This function generally should be called in attach, but (except in some
49race cases) never earlier.
50.Pp
51Its arguments are as follows:
52.Bl -item
53.It
54.Fa dev
55is the device that requests ownership of the resource.
56Before allocation, the resource is owned by the parent bus.
57.It
58.Fa type
59is the type of resource you want to allocate.
60It is one of:
61.Bl -tag -width SYS_RES_MEMORY
62.It Dv SYS_RES_IRQ
63for IRQs
64.It Dv SYS_RES_DRQ
65for ISA DMA lines
66.It Dv SYS_RES_IOPORT
67for I/O ports
68.It Dv SYS_RES_MEMORY
69for I/O memory
70.El
71.It
72.Fa rid
73points to a bus specific handle that identifies the resource being allocated.
74For ISA this is an index into an array of resources that have been setup
75for this device by either the PnP mechanism, or via the hints mechanism.
76For PCCARD, similar things are used as of writing,
77but that may change in the future with newcard.
78For PCI it just happens to be the offset into pci config space which has
79a word that describes the resource.
80The bus methods are free to change the RIDs that they are given as a parameter.
81You must not depend on the value you gave it earlier.
82.It
83.Fa start
84and
85.Fa end
86are the start/end addresses of the resource.
87If you specify values of
88.Dv 0
89for start and
90.Dv ~0
91for end, the default values for the bus are calculated.
92.It
93.Fa count
94is the size of the resource, e.g. the size of an I/O port (often
95.Dv 1
96on PCI and device-dependent on ISA and PCCARD).
97If you specified the default values for
98.Fa start
99and
100.Fa end ,
101then the default value of the bus is used if
102.Fa count
103is smaller than the default value and
104.Fa count
105is used, if it is bigger as the default value.
106.It
107.Fa flags
108sets the flags for the resource.
109You can set one or more of these flags:
110.Bl -tag -width RF_SHAREABLE
111.It Dv RF_ALLOCATED
112resource has been reserved.
113The resource still needs to be activated with
114.Xr rman_activate_resource 9 .
115.It Dv RF_ACTIVE
116activate resource atomically.
117.It Dv RF_SHAREABLE
118resource permits contemporaneous sharing.
119Should always be set unless you know, that the resource cannot be shared.
120It is the bus-code's task to filter out the flag if the bus doesn't
121support sharing, which is, for example, the case for pccard/cardbus,
122which can or can not share devices, depending on the bus.
123.It Dv RF_TIMESHARE
124resource permits time-division sharing.
125.El
126.El
127.Sh RETURN VALUES
128A pointer to
129.Va struct res
130is returned on success, a null pointer otherwise.
131.Sh EXAMPLES
132This is some example code.
133The values of
134.Va portid
135and
136.Va irqid
137should be saved in the softc of the device after these calls.
138.Bd -literal
139	struct resource *portres, irqres;
140	int portid, irqid;
141
142	portid = 0;
143	irqid = 0;
144	portres = bus_alloc_resource(dev, SYS_RES_IOPORT, &portid,
145			0ul, ~0ul, 32, RF_ACTIVE);
146	irqres = bus_alloc_resource(dev, SYS_RES_IRQ, &irqid,
147			0ul, ~0ul, 1, RF_ACTIVE | RF_SHAREABLE);
148.Ed
149.Sh SEE ALSO
150.Xr driver 9 ,
151.Xr device 9 ,
152.Xr bus_release_resource 9
153.Sh AUTHORS
154.An -nosplit
155This man page was written by
156.An Alexander Langer Aq alex@big.endian.de
157with parts by
158.An Warner Losh Aq imp@FreeBSD.org .
159