sensor直接连接到应用处理器，并有linuxkernel管理。本文涉及到kernel驱动，sensor HAL以及SensorService。
sensor架构
安卓提供Sensor API和SensorManager，然而没有提供Sensor HAL和sensor驱动。
电源管理和管脚功能设置在设备树中应当设置好，Sensor类用于支持一些新特性。增加了一些sensor新特性，如：NativeSensorManager,，CalibrationManager,虚拟传感器支持，
传感器驱动
内核sensor驱动，包括电源，pin脚，传感器类，通常传感器驱动位于drivers/input/misc/。
传感器的电源
设备树配置
传感器芯片的驱动由sensor的probe驱动设置，mmc3416xpj的配置驱动如下：
1
2
3
4
5
6
7
8memsic@30 { /* Magnetic field sensor */ compatible = "memsic,mmc3416x"; reg = <0x30>; vdd-supply = <&pm8916_l17>; vio-supply = <&pm8916_l6>; memsic,dir = "obverse-x-axis-forward"; memsic,auto-report; };
vio-supply：IO和I2C需要的数字电源，pm8916_l6是电源管理器
1arch/arm/boot/dts/qcom/xxxx-regulator.dtsi
1kernel/Documentation/bindings/input/misc/ .
regulator
在操作sensor chip之前需要初始化该芯片，regulator_get，regualator_count_voltages，regulator_set_voltages , regulator_enable ,以及regulator_disable。
管脚控制
设备树配置
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26akm@c { compatible = "ak,ak09911"; reg = <0x0c>; pinctrl-names = "default","sleep"; pinctrl-0 = <&akm_default>; pinctrl-1 = <&akm_sleep>; vdd-supply = <&pm8916_l17>; vio-supply = <&pm8916_l6>; akm,layout = <0x3>; akm,gpio_rstn = <&msm_gpio 36 0x0>; akm,auto-report; }; akm_reset_pin { qcom,pins = <&gp 36>; qcom,pin-func = <0>; qcom,num-grp-pins = <1>; label = "akm_reset_pin"; akm_default: akm_default { drive-strength = <6>; bias-pull-up; }; akm_sleep: akm_sleep { drive-strength = <2>; bias-pull-down; }; };
pinctrl初始化
在probe是被调用。
pinctrl_get()--获得设备的pinctrl
pinctrl_lookup_state()--获取管脚状态
pinctrl_select_state()--设置硬件管脚状态
可以参考drivers/input/misc/akm09911.c提供的pin脚相关详细信息。
Sensor 类支持
这个是sensor类框架如下：
为了支持这一通用架构，需要按增加一些callback支持。
1.添加头文件
1#include <linux/sensors.h>
1
2
3
4
5static struct sensors_classdev sensors_cdev; struct sensor_data { ... ... struct sensors_classdev cdev; }
1sensors_classdev_register(&client->dev, &sensor_data->cdev);
4.在注册设备之前填充结构体相关字段
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16.name = "kxtj9-accel", .vendor = "Kionix", .version = 1, .handle = 0, .type = 1, .max_range = "19.6", .resolution = "0.01", .sensor_power = "0.2", .min_delay = 2000, .fifo_reserved_event_count = 0, .fifo_max_event_count = 0, .enabled = 0 .delay_msec = 200, .sensors_enable = NULL, .sensors_poll_delay = NULL, }
1
2data->cdev.sensors_enable = sensor_enable_set; data->cdev.sensors_poll_delay = sensor_poll_delay_set;
推荐使用cdev name注册到sensor类。
Native sensor HAL
其定义于
1hardware/libhardware/include/hardware/sensors.h
CalibrationManager
数据结构
CalibrationManager加载第三方校正库，calibration 模块数据被用于HAL和第三方库，定义于：
1hardware/qcom/sensors/CalibrationModule.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64struct sensor_cal_algo_t; struct sensor_cal_module_t; struct sensor_algo_args { int enable; int delay_ms; struct sensor_t sensor; int (*store_calibrate_params)(struct sensor_t *sensor, struct sensors_event_t *bias); }; struct compass_algo_args { struct sensor_algo_args common; uint32_t reserved[16]; }; struct gyro_algo_args { struct sensor_algo_args common; float bias[3]; }; struct sensor_algo_methods_t { int (*convert)(sensors_event_t *raw, sensors_event_t *result, struct sensor_algo_args *args); /* Note that the config callback is called from a different thread as convert */ int (*config)(int cmd, struct sensor_algo_args *args); }; struct sensor_cal_methods_t { int (*init)(const struct sensor_cal_module_t* module, struct sensor_algo_args *args); void (*deinit)(); /* Return 0 on success */ int (*get_algo_list)(const struct sensor_cal_algo_t **algo); }; struct sensor_cal_algo_t { /* Tag of the algo */ int tag; /* Version of the algo */ int version; /* Type of sensor this algo supported*/ int type; /* The compatible sensors */ const char **compatible; /* Sensor calibration module */ struct sensor_cal_module_t *module; /* Sensor algo methods */ struct sensor_algo_methods_t *methods; }; struct sensor_cal_module_t { /* Tag of the module */ uint32_t tag; /* Id of the module */ char *id; /* Version of the calibration module */ uint32_t version; /* Vendor of the calibration lib */ char *vendor; /* Point to the handle of this module */ void *dso; /* Number of algos */ uint32_t number; /* Callbacks of the calibration lib provided */ struct sensor_cal_methods_t *methods; /* The compatible sensors list for this library */ int reserved[6]; };
1
2
3
4
5
6
7struct sensor_algo_methods_t { int (*convert)(sensors_event_t *raw, sensors_event_t *result, struct sensor_algo_args *args); /* Note that the config callback is called from a different thread as convert */ int (*config)(int cmd, struct sensor_algo_args *args); };
校正库
校正库可以放在安卓代码库的任何地方，校正库应当被编译成一个共享库，该库位于system/vendor/lib，Sensor HAL使用兼容表选择校正算法，所以兼容表必须被正确设置，
1hardware/qcom/sensors/algo/common/common_wrapper.c
NativeSensorManager
NativeSensorManager的源代码位于hardware/qcom/sensors/；
图：call和poll流程
NativeSensorManager初始化
NativeSensorManager也许会在open_sensors之前被调用。
初始化过程如下：
1.扫描/dev/input目录，并获得传感器的路径名和设备名
2.通过/sys/class/sensors获得sensor list。
3.将sensor list和设备节点路径相关联
4.初始化硬件驱动（sensorBase 子类）
5.初始化虚拟sensor
命令和数据流管理
NativeSensorManager接收所有的命令和数据。
虚拟设备管理
NativeSensorManager管理，支持的设备是Orientation, Linear Acceleration, Gravity, Rotation Vector, Pseudo Gyroscope, and Uncalibrated Magnetic Field。
最后
以上就是甜美棉花糖最近收集整理的关于android sensor移植的全部内容，更多相关android内容请搜索靠谱客的其他文章。
发表评论 取消回复