xref: /dragonfly/share/man/man9/make_dev.9 (revision 36a3d1d6) 
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25.\" $FreeBSD: src/share/man/man9/make_dev.9,v 1.2.2.3 2001/12/17 11:30:18 ru Exp $
26.\"
27.Dd September 11, 2009
28.Os
29.Dt MAKE_DEV 9
30.Sh NAME
31.Nm destroy_dev ,
32.Nm destroy_only_dev ,
33.Nm devfs_scan_callback ,
34.Nm dev_ops_intercept ,
35.Nm dev_ops_remove_all ,
36.Nm dev_ops_remove_minor ,
37.Nm dev_ops_restore ,
38.Nm make_dev ,
39.Nm make_dev_alias ,
40.Nm make_only_dev ,
41.Nm reference_dev ,
42.Nm release_dev
43.Nd "device entry manipulation functions"
44.Sh SYNOPSIS
45.In sys/types.h
46.In sys/conf.h
47.In sys/devfs.h
48.Ft void
49.Fn destroy_dev "cdev_t dev"
50.Ft void
51.Fn destroy_only_dev "cdev_t dev"
52.Ft int
53.Fn devfs_scan_callback "devfs_scan_t *callback"
54.Ft struct dev_ops *
55.Fn dev_ops_intercept "cdev_t dev" "struct dev_ops *iops"
56.Ft int
57.Fn dev_ops_remove_all "struct dev_ops *ops"
58.Ft void
59.Fn dev_ops_restore "cdev_t dev" "struct dev_ops *oops"
60.Ft int
61.Fn dev_ops_remove_minor "struct dev_ops *ops" "int minor"
62.Ft cdev_t
63.Fn make_dev "struct dev_ops *ops" "int minor" "uid_t uid" "gid_t gid" "int perms" "char *fmt" ...
64.Ft int
65.Fn make_dev_alias "cdev_t target" "const char *fmt" ...
66.Ft cdev_t
67.Fn make_dev_covering "struct dev_ops *ops" "cdev_t rdev" "int minor" "uid_t uid" "gid_t gid" "int perms" "char *fmt" ...
68.Ft cdev_t
69.Fn make_only_dev "struct dev_ops *ops" "int minor" "uid_t uid" "gid_t gid" "int perms" "const char *fmt" ...
70.Ft cdev_t
71.Fn reference_dev "cdev_t dev"
72.Ft void
73.Fn release_dev "cdev_t dev"
74.Sh DESCRIPTION
75The
76.Fn make_dev
77function creates a
78.Vt cdev_t
79structure for a new device and makes the device name visible in the
80.Xr devfs 5
81mount points.
82The device's name must be unique.
83The name is the expansion of
84.Fa fmt
85and following arguments as
86.Xr kprintf 9
87would print it.
88The name determines its path under
89.Pa /dev .
90The permissions of the file specified in
91.Fa perms
92are defined in
93.In sys/stat.h :
94.Pp
95.Bd -literal -offset indent -compact
96#define S_IRWXU 0000700    /* RWX mask for owner */
97#define S_IRUSR 0000400    /* R for owner */
98#define S_IWUSR 0000200    /* W for owner */
99#define S_IXUSR 0000100    /* X for owner */
100
101#define S_IRWXG 0000070    /* RWX mask for group */
102#define S_IRGRP 0000040    /* R for group */
103#define S_IWGRP 0000020    /* W for group */
104#define S_IXGRP 0000010    /* X for group */
105
106#define S_IRWXO 0000007    /* RWX mask for other */
107#define S_IROTH 0000004    /* R for other */
108#define S_IWOTH 0000002    /* W for other */
109#define S_IXOTH 0000001    /* X for other */
110
111#define S_ISUID 0004000    /* set user id on execution */
112#define S_ISGID 0002000    /* set group id on execution */
113#define S_ISVTX 0001000    /* sticky bit */
114#ifndef _POSIX_SOURCE
115#define S_ISTXT 0001000
116#endif
117.Ed
118.Pp
119The
120.Fa ops
121argument is a pointer to a
122.Vt dev_ops
123data structure, which is defined as follows:
124.Bd -literal
125struct dev_ops {
126        struct {
127                const char      *name;  /* base name, e.g. 'da' */
128                int              maj;   /* major device number */
129                u_int            flags; /* D_XXX flags */
130                void            *data;  /* custom driver data */
131                int              refs;  /* ref count */
132                int              id;
133        } head;
134
135#define dev_ops_first_field     d_default
136        d_default_t     *d_default;
137        d_open_t        *d_open;
138        d_close_t       *d_close;
139        d_read_t        *d_read;
140        d_write_t       *d_write;
141        d_ioctl_t       *d_ioctl;
142        d_mmap_t        *d_mmap;
143        d_strategy_t    *d_strategy;
144        d_dump_t        *d_dump;
145        d_psize_t       *d_psize;
146        d_kqfilter_t    *d_kqfilter;
147        d_clone_t       *d_clone;       /* clone from base dev_ops */
148        d_revoke_t      *d_revoke;
149#define dev_ops_last_field      d_revoke
150};
151.Ed
152.Pp
153While one can and should initialize the
154.Fa name
155and
156.Fa maj
157fields, they are effectively ignored.
158Device major numbers are assigned automatically out of an internal pool of
159major numbers, so there is no need to specify a unique major number in the
160.Vt dev_ops
161structure.
162.Pp
163Every member of the
164.Fn d_xxx_t
165family is defined as:
166.Bd -literal
167typedef int d_xxx_t (struct dev_xxx_args *ap);
168.Ed
169.Pp
170Therefore, if one wants to implement a
171.Fn mydev_open
172function, this is the way:
173.Bd -literal
174d_open_t mydev_open;
175
176int
177mydev_open(struct dev_open_args *ap)
178{
179}
180.Ed
181.Pp
182.Fn make_dev_covering
183is equivalent to make_dev, except that it also takes an argument
184.Vt cdev_t rdev
185which is set as the backing device for the newly created device.
186This function should be used whenever a device is created covering
187another raw device, as the disk subsystem does.
188.Pp
189.Fn make_only_dev
190creates a
191.Vt cdev_t
192structure and initializes it the same way
193.Fn make_dev
194would, but the device will not appear in the
195.Xr devfs 5
196namespace.
197.Pp
198.Fn destroy_dev
199takes the returned
200.Vt cdev_t
201from
202.Fn make_dev
203and destroys the registration for that device.
204It should not be used to destroy a
205.Vt cdev_t
206created by
207.Fn make_only_dev .
208.Pp
209.Fn destroy_only_dev
210takes the returned
211.Vt cdev_t
212from
213.Fn make_only_dev
214and destroys the registration for that device.
215It should not be used to destroy a
216.Vt cdev_t
217created by
218.Fn make_dev .
219.Pp
220.Fn make_dev_alias
221creates an automatic
222.Xr devfs 5
223link (alias) with the given name to the
224.Vt cdev_t
225specified by
226.Fa target .
227The
228.Vt cdev_t
229must have been created either by
230.Fn make_dev
231or bt a clone handler.
232Aliases are alternative names for devices in the
233.Xr devfs 5
234namespace.
235The lifetime of an alias is that of its associated
236.Vt cdev_t .
237Once the
238.Vt cdev_t
239is removed or destroyed, the alias is also destroyed and its name is
240removed from the
241.Xr devfs 5
242namespace.
243.Pp
244.Fn reference_dev
245adds a reference to
246.Fa dev .
247Callers generally add their own references when they are going to store a device
248node in a variable for long periods of time, to prevent a disassociation from
249freeing the node.
250.Pp
251.Fn release_dev
252releases a reference on
253.Fa dev .
254The device will be terminated when the last reference has been released.
255.Pp
256.Fn dev_ops_intercept
257intercepts the device operations vector of
258.Fa dev
259with
260.Fa iops .
261The old
262.Vt dev_ops
263is returned which may be used in a subsequent
264.Fn dev_ops_restore
265call.
266The function sets the
267.Dv SI_INTERCEPTED
268flag in
269.Fa dev .
270.Pp
271.Fn dev_ops_restore
272restores the device operations vector of
273.Fa dev
274to
275.Fa oops .
276Also it unsets the
277.Dv SI_INTERCEPTED
278flag in
279.Fa dev .
280.Pp
281.Fn dev_ops_remove_all
282destroys all the
283.Vt cdev_t
284with the given
285.Fa ops
286and removes the devices from the
287.Xr devfs 5
288namespace.
289This function is useful when uninitializing a driver.
290.Pp
291.Fn dev_ops_remove_minor
292destroys all the
293.Vt cdev_t
294with the given
295.Fa ops
296and
297.Fa minor
298and removes the devices from the
299.Xr devfs 5
300namespace.
301.Pp
302.Fn devfs_scan_callback
303calls the given
304.Fa callback
305function for every device registered in
306.Xr devfs 5 .
307The
308.Fa callback
309function has the following form:
310.Bd -literal
311devfs_scan_t mydev_scan_callback;
312
313void
314mydev_scan_callback(cdev_t dev)
315{
316};
317.Ed
318.Sh HISTORY
319The
320.Fn make_dev
321and
322.Fn destroy_dev
323functions first appeared in
324.Fx 4.0 .
325.Pp
326A major overhaul of these functions occurred in
327.Dx 2.3
328with the addition of
329.Xr devfs 5 .
330