xref: /freebsd/share/man/man9/bus_alloc_resource.9 (revision 7660b554bc59a07be0431c17e0e33815818baa69)
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29.\" $FreeBSD$
30.\"
31.Dd May 18, 2000
32.Dt BUS_ALLOC_RESOURCE 9
33.Os
34.Sh NAME
35.Nm bus_alloc_resource
36.Nd alloc resources on a bus
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 struct resource *
45.Fn bus_alloc_resource "device_t dev" "int type" "int *rid" "u_long start" "u_long end" "u_long count" "u_int flags"
46.Sh DESCRIPTION
47This is an easy interface to the resource-management functions.
48It hides the indirection through the parent's method table.
49This function generally should be called in attach, but (except in some
50rare cases) never earlier.
51.Pp
52Its arguments are as follows:
53.Bl -item
54.It
55.Fa dev
56is the device that requests ownership of the resource.
57Before allocation, the resource is owned by the parent bus.
58.It
59.Fa type
60is the type of resource you want to allocate.
61It is one of:
62.Bl -tag -width SYS_RES_MEMORY
63.It Dv SYS_RES_IRQ
64for IRQs
65.It Dv SYS_RES_DRQ
66for ISA DMA lines
67.It Dv SYS_RES_IOPORT
68for I/O ports
69.It Dv SYS_RES_MEMORY
70for I/O memory
71.El
72.It
73.Fa rid
74points to a bus specific handle that identifies the resource being allocated.
75For ISA this is an index into an array of resources that have been setup
76for this device by either the PnP mechanism, or via the hints mechanism.
77For PCCARD, similar things are used as of writing,
78but that may change in the future with newcard.
79For PCI it just happens to be the offset into pci config space which has
80a word that describes the resource.
81The bus methods are free to change the RIDs that they are given as a parameter.
82You must not depend on the value you gave it earlier.
83.It
84.Fa start
85and
86.Fa end
87are the start/end addresses of the resource.
88If you specify values of 0 for
89.Fa start
90and ~0 for
91.Fa end
92and 1 for
93.Fa count ,
94the default values for the bus are calculated.
95.It
96.Fa count
97is the size of the resource, e.g. the size of an I/O port (often
981, but some devices override this).
99If you specified the default values for
100.Fa start
101and
102.Fa end ,
103then the default value of the bus is used if
104.Fa count
105is smaller than the default value and
106.Fa count
107is used, if it is bigger as the default value.
108.It
109.Fa flags
110sets the flags for the resource.
111You can set one or more of these flags:
112.Bl -tag -width RF_SHAREABLE
113.It Dv RF_ALLOCATED
114resource has been reserved.
115The resource still needs to be activated with
116.Xr bus_activate_resource 9 .
117.It Dv RF_ACTIVE
118activate resource atomically.
119.It Dv RF_SHAREABLE
120resource permits contemporaneous sharing.
121Should always be set unless you know, that the resource cannot be shared.
122It is the bus-code's task to filter out the flag if the bus doesn't
123support sharing, which is, for example, the case for pccard/cardbus,
124which can or cannot share devices, depending on the bus.
125.It Dv RF_TIMESHARE
126resource permits time-division sharing.
127.El
128.El
129.Sh RETURN VALUES
130A pointer to
131.Va struct res
132is returned on success, a null pointer otherwise.
133.Sh EXAMPLES
134This is some example code.
135The values of
136.Va portid
137and
138.Va irqid
139should be saved in the softc of the device after these calls.
140.Bd -literal
141	struct resource *portres, irqres;
142	int portid, irqid;
143
144	portid = 0;
145	irqid = 0;
146	portres = bus_alloc_resource(dev, SYS_RES_IOPORT, &portid,
147			0ul, ~0ul, 32, RF_ACTIVE);
148	irqres = bus_alloc_resource(dev, SYS_RES_IRQ, &irqid,
149			0ul, ~0ul, 1, RF_ACTIVE | RF_SHAREABLE);
150.Ed
151.Sh SEE ALSO
152.Xr bus_activate_resource 9 ,
153.Xr bus_release_resource 9 ,
154.Xr device 9 ,
155.Xr driver 9
156.Sh AUTHORS
157.An -nosplit
158This man page was written by
159.An Alexander Langer Aq alex@big.endian.de
160with parts by
161.An Warner Losh Aq imp@FreeBSD.org .
162