84d35492b1
Inheritance of HAL object is performed by composing a child structure of a
single parent structure located at offset 0 followed by new data members
and function pointers in the child structure.
For example,
struct child {
struct parent common;
int a_data_member;
void (*a_method)(struct child *c, int v);
};
HAL code assumes this layout when accessing child structures given a pointer
to a parent structure such that users write code like the following...
void child_method(struct *parent, int v) {
struct child * c = (struct child*)parent;
// do stuff with c
}
Code above will break if a member is added before "common" in "struct child".
This change adds comments that describe the restriction on the location of
parent HAL objects within a derived HAL object. HAL objects that already
have comments that describe the required location of parent objects are not
modified.
Change-Id: Ibe4300275286ef275b2097534c84f1029d761d87
123 lines
3.8 KiB
C
123 lines
3.8 KiB
C
/*
|
|
* Copyright (C) 2011 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
|
|
#ifndef ANDROID_LOCAL_TIME_HAL_INTERFACE_H
|
|
#define ANDROID_LOCAL_TIME_HAL_INTERFACE_H
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <hardware/hardware.h>
|
|
|
|
__BEGIN_DECLS
|
|
|
|
/**
|
|
* The id of this module
|
|
*/
|
|
#define LOCAL_TIME_HARDWARE_MODULE_ID "local_time"
|
|
|
|
/**
|
|
* Name of the local time devices to open
|
|
*/
|
|
#define LOCAL_TIME_HARDWARE_INTERFACE "local_time_hw_if"
|
|
|
|
/**********************************************************************/
|
|
|
|
/**
|
|
* A structure used to collect low level sync data in a lab environment. Most
|
|
* HAL implementations will never need this structure.
|
|
*/
|
|
struct local_time_debug_event {
|
|
int64_t local_timesync_event_id;
|
|
int64_t local_time;
|
|
};
|
|
|
|
/**
|
|
* Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
|
|
* and the fields of this data structure must begin with hw_module_t
|
|
* followed by module specific information.
|
|
*/
|
|
struct local_time_module {
|
|
struct hw_module_t common;
|
|
};
|
|
|
|
struct local_time_hw_device {
|
|
/**
|
|
* Common methods of the local time hardware device. This *must* be the first member of
|
|
* local_time_hw_device as users of this structure will cast a hw_device_t to
|
|
* local_time_hw_device pointer in contexts where it's known the hw_device_t references a
|
|
* local_time_hw_device.
|
|
*/
|
|
struct hw_device_t common;
|
|
|
|
/**
|
|
*
|
|
* Returns the current value of the system wide local time counter
|
|
*/
|
|
int64_t (*get_local_time)(struct local_time_hw_device* dev);
|
|
|
|
/**
|
|
*
|
|
* Returns the nominal frequency (in hertz) of the system wide local time
|
|
* counter
|
|
*/
|
|
uint64_t (*get_local_freq)(struct local_time_hw_device* dev);
|
|
|
|
/**
|
|
*
|
|
* Sets the HW slew rate of oscillator which drives the system wide local
|
|
* time counter. On success, platforms should return 0. Platforms which
|
|
* do not support HW slew should leave this method set to NULL.
|
|
*
|
|
* Valid values for rate range from MIN_INT16 to MAX_INT16. Platform
|
|
* implementations should attempt map this range linearly to the min/max
|
|
* slew rate of their hardware.
|
|
*/
|
|
int (*set_local_slew)(struct local_time_hw_device* dev, int16_t rate);
|
|
|
|
/**
|
|
*
|
|
* A method used to collect low level sync data in a lab environments.
|
|
* Most HAL implementations will simply set this member to NULL, or return
|
|
* -EINVAL to indicate that this functionality is not supported.
|
|
* Production HALs should never support this method.
|
|
*/
|
|
int (*get_debug_log)(struct local_time_hw_device* dev,
|
|
struct local_time_debug_event* records,
|
|
int max_records);
|
|
};
|
|
|
|
typedef struct local_time_hw_device local_time_hw_device_t;
|
|
|
|
/** convenience API for opening and closing a supported device */
|
|
|
|
static inline int local_time_hw_device_open(
|
|
const struct hw_module_t* module,
|
|
struct local_time_hw_device** device)
|
|
{
|
|
return module->methods->open(module, LOCAL_TIME_HARDWARE_INTERFACE,
|
|
(struct hw_device_t**)device);
|
|
}
|
|
|
|
static inline int local_time_hw_device_close(struct local_time_hw_device* device)
|
|
{
|
|
return device->common.close(&device->common);
|
|
}
|
|
|
|
|
|
__END_DECLS
|
|
|
|
#endif // ANDROID_LOCAL_TIME_INTERFACE_H
|