Copyright (c) 2009 David Young <dyoung@NetBSD.org>
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NetBSD: pmf.9,v 1.12 2009/10/21 16:06:59 snj Exp
Copyright (c) 2007 Jared D. McNeill <jmcneill@invisible.ca>
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.Dd November 4, 2009 .Dt DEVITER 9 .Os .Sh NAME .Nm deviter , .Nm deviter_first , .Nm deviter_init , .Nm deviter_next , .Nm deviter_release .Nd machine-independent device iteration API .Sh SYNOPSIS n sys/device.h .Ft void .Fn deviter_init "deviter_t *di" "deviter_flags_t flags" .Ft device_t .Fn deviter_first "deviter_t *di" "deviter_flags_t flags" .Ft device_t .Fn deviter_next "deviter_t *di" .Ft void .Fn deviter_release "deviter_t *di" .Sh DESCRIPTION The machine-independent .Nm API lets interrupt handlers running at any priority level and kernel threads iterate over the devices attached to the kernel. Using .Nm , it is safe for an interrupt handler or a thread to iterate over devices attached to the kernel while another thread attaches or detaches the devices. .Sh DATA TYPES Kernel subsystems using .Nm may make use of the following data types: l -tag -width compact t Fa deviter_flags_t The kernel can iterate over devices for different purposes and in different orders. The following flags affect device iteration: l -item -compact -offset indent t .Dv DEVITER_F_RW t .Dv DEVITER_F_SHUTDOWN t .Dv DEVITER_F_LEAVES_FIRST t .Dv DEVITER_F_ROOT_FIRST .El t Fa deviter_t This is a device iteration .Dq cursor or .Dq iterator . It holds iteration state such as the next device to visit. .El .Sh FUNCTIONS l -tag -width compact t Fn deviter_init "di" "flags" Initialize the device iterator, .Fa di . Set bits in .Fa flags to affect the order of iteration. Set .Dv DEVITER_F_LEAVES_FIRST to visit each device only after visiting its children (visit the leaves of the device tree, first). Set .Dv DEVITER_F_ROOT_FIRST to visit each device before visiting its children (visit the root of the device tree, first). If you set neither .Dv DEVITER_F_LEAVES_FIRST nor .Dv DEVITER_F_ROOT_FIRST , .Nm returns devices in an arbitrary order.
p Set .Dv DEVITER_F_RW if your purpose for iterating over devices is to modify the device tree by attaching or detaching devices. Set .Dv DEVITER_F_SHUTDOWN if your purpose for iterating over devices is to detach all of the devices during system shutdown. .Dv DEVITER_F_SHUTDOWN implies .Dv DEVITER_F_RW . t Fn deviter_next "di" Advance the iterator .Fa di to the next device. .Fn deviter_next returns the current device or .Dv NULL if there are no more devices. .Fn deviter_next is undefined if .Fa di has not been initialized using .Fn deviter_init or .Fn deviter_first . t Fn deviter_first "di" "flags" Initialize the iterator .Fa di with .Fa flags . Return the first device according to the ordering indicated by .Fa flags and advance .Fa di to the second device, or return .Dv NULL if there are no devices. This is equivalent to calling .Fn deviter_init "di" "flags" and then .Fn deviter_next "di" . t Fn deviter_release "di" Release all resources held by the iterator .Fa di . Every iterator that is initialized with .Fn deviter_first or .Fn deviter_init MUST be released. .El .Sh CODE REFERENCES Device iteration is implemented within the files
a sys/kern/subr_autoconf.c . .Sh SEE ALSO .Xr autoconf 9 , .Xr driver 9 .Sh HISTORY .Nm appeared in .Nx 5.0 . .Sh AUTHORS .An David Young Aq dyoung@NetBSD.org