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/*
* Copyright © 2017-2022 The Crust Firmware Authors.
* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only
*/
#ifndef COMMON_DEVICE_H
#define COMMON_DEVICE_H
#include <stdbool.h>
#include <stdint.h>
/**
* Default initializer for the device state pointer.
*
* The state pointer must be initialized for all devices. If additional mutable
* state is needed, wrap struct device_state intrusively. Otherwise, use this
* macro.
*/
#define DEVICE_STATE_INIT &(struct device_state) { 0 }
struct device_state;
struct driver;
struct device {
/** A unique name for this device. */
const char *name;
/** The driver for this device. */
const struct driver *drv;
/** Mutable state for this device. */
struct device_state *state;
};
struct device_state {
/** Reference count for this device. */
uint8_t refcount;
};
struct driver {
/** A function called to detect and initialize new devices. */
int (*probe)(const struct device *dev);
/** A function called to uninitialize devices and free resources. */
void (*release)(const struct device *dev);
};
/**
* Determine if a device is active (if it has any outstanding references).
*
* @param dev A device.
* @return The state of the device.
*/
bool device_active(const struct device *dev);
/**
* Get a reference to a device.
*
* If this is the first reference to a device, that device's driver will be
* initialized. Otherwise, this function only updates the reference count.
*
* The device will remain running as long as the reference is held (that is,
* until calling device_put()).
*
* If this function returns an error, do not call device_put().
*
* @param dev A device.
*
* @return Zero on success; an error code on failure.
*/
int device_get(const struct device *dev);
/**
* Get a reference to a device.
*
* @return A reference to the device that was acquired, or a NULL pointer.
*/
const struct device *device_get_or_null(const struct device *dev);
/**
* Release a reference to a device.
*
* @param dev A reference to a device.
*/
void device_put(const struct device *dev);
/**
* Implementation of the device probe function that does nothing.
*/
int dummy_probe(const struct device *dev);
/**
* Implementation of the device release function that does nothing.
*/
void dummy_release(const struct device *dev);
#endif /* COMMON_DEVICE_H */
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