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      1 $NetBSD: device_calls,v 1.4 2025/10/04 01:12:15 thorpej Exp $
      2 
      3 /*-
      4  * Copyright (c) 2021, 2025 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Device calls used by the device autoconfiguration subsystem
     34  */
     35 
     36 subsystem device;
     37 
     38 /*
     39  * device-enumerate-children
     40  *
     41  * Enumerates the direct children of a device, invoking the callback for
     42  * each one.  The callback is passed the devhandle_t corresponding to the
     43  * child device, as well as a user-supplied argument.  If the callback
     44  * returns true, then enumeration continues.  If the callback returns false,
     45  * enumeration is stopped.
     46  */
     47 device-enumerate-children {
     48 	bool	(*callback)(device_t, devhandle_t, void *);
     49 	void *	callback_arg;
     50 };
     51 
     52 /*
     53  * device-register
     54  *
     55  * This is a hook for the platform device tree implementation to
     56  * inspect or take action upon a new device before the machine-
     57  * specific device_register() function is called.
     58  */
     59 device-register {
     60 	void *	aux;		/* IN */
     61 };
     62 
     63 /*
     64  * device-is-system-todr
     65  *
     66  * This is a filter that is considered when attaching the system TODR / RTC.
     67  * For systems which may have multiple TODR / RTC devices, the platform
     68  * device tree may have information about which is authoritative.  This is
     69  * an optional method, and in its absence, the system will proceed as if
     70  * the answer was "yes".
     71  */
     72 device-is-system-todr {
     73 	bool	result;		/* OUT */
     74 };
     75 
     76 /*
     77  * device-get-property
     78  *
     79  * Gets the specified property (and its attributes) and copies it into
     80  * the caller-provided buffer, in addtion to returning the property's
     81  * attributes:
     82  * ==> propsize		The native size of the property in the backing
     83  *			store.
     84  * ==> encoding		The native encoding of numbers in the backing store,
     85  *			_BIG_ENDIAN or _LITTLE_ENDIAN.
     86  * ==> type		The native type of the property in the backing store.
     87  *			If the backing store does not have a native typing
     88  *			system, then it may return PROP_TYPE_UNKNOWN for this
     89  *			attribute.
     90  *
     91  * If the requested property type is PROP_TYPE_UNKNOWN, then the pointer to
     92  * and size of the caller-provided buffer shall be NULL and 0, respectively.
     93  * Implementations may assert this.  In this instance, the caller is requesting
     94  * only the property's attributes.
     95  *
     96  * Conversely, if the requested property type is not PROP_TYPE_UNKNOWN,
     97  * then the pointer to the caller-provided buffer shall not be NULL and
     98  * the size shall not be 0, and the type will be one of the four listed
     99  * below.  Implementation may assert this.
    100  *
    101  * If the requested property type is PROP_TYPE_DATA or PROP_TYPE_STRING,
    102  * then the following rules apply:
    103  * ==> If the caller-provided buffer is insufficiently large to hold the
    104  *     entire property, the "propsize" output must be set to reflect the
    105  *     required buffer size and the EFBIG error returned.  In this situation,
    106  *     it is unspecified whether or not any data is copied into the caller-
    107  *     provided buffer.
    108  * ==> If the backing store has a native STRING type, then the implementation
    109  *     must allow STRING properties to be fetched as DATA objects.
    110  *
    111  * If the requested type is PROP_TYPE_STRING, the property value in returned
    112  * in the caller-provided buffer must be NUL-terminated.
    113  *
    114  * If the requested property type is PROP_TYPE_NUMBER, then the following
    115  * rules apply:
    116  * ==> The size of the caller-provided buffer shall be sizeof(uint64_t) and
    117  *     will have alignment suitable for the type.  Implementations may assert
    118  *     this.
    119  * ==> The implementation must silently zero-extend whatever value is in the
    120  *     backing store to a uint64_t and return that value.  The front-end
    121  *     will perform any type conversions, including range checks, requested
    122  *     by the caller.
    123  * ==> The returned "propsize" must reflect an accurate representation of
    124  *     the size of the property in the backing store; this information is
    125  *     is used in type conversion.
    126  * ==> If the backing store's number encoding differs from the native number
    127  *     encoding, then the backing store shall convert the number to the native
    128  *     encoding.
    129  *
    130  * If the requested property type is PROP_TYPE_BOOL, then the following
    131  * rules apply:
    132  * ==> The size of the caller-provided buffer shall be sizeof(bool) and will
    133  *     have alignment suitable for the type.  Implementations may assert this.
    134  * ==> If the implementation's backing store does not provide a native boolean
    135  *     type, then the implementation may use backing-store-specific conventions
    136  *     to infer bool-ness of the property.  If, in this situation, the property
    137  *     does not match the backing store's boolean conventions, then the
    138  *     implementation must return EFTYPE; the system will then use its own
    139  *     default policy as a fallback.
    140  *
    141  * Call returns 0 if successful, or an error code upon failure:
    142  *
    143  * ENOENT	The property does not exist.
    144  *
    145  * EFBIG	The property is too large to fit in the provided buffer.
    146  *		The "propsize" output is set to reflect the required
    147  *		buffer size (for DATA and STRING properties).
    148  *
    149  * EFTYPE	The property is a different type than what was requested.
    150  *
    151  * EINVAL	The arguments provided to the call are invalid in a way
    152  *		not covered by one of the above error cases.
    153  *
    154  * EIO		An input/output error to the backing store occurred.
    155  *
    156  * The "flags" field of the arguments structure is reserved for future
    157  * expansion.
    158  *
    159  * The "dev" argument to the device-get-property call may be NULL.
    160  */
    161 device-get-property {
    162 	const char *	prop;		/* IN */
    163 	void *		buf;		/* IN */
    164 	size_t		buflen;		/* IN */
    165 	prop_type_t	reqtype;	/* IN */
    166 	int		flags;		/* IN */
    167 	ssize_t		propsize;	/* OUT */
    168 	int		encoding;	/* OUT */
    169 	prop_type_t	type;		/* OUT */
    170 };
    171