rk3188--7.android gsensor驱动分析

g_sensor好像很简单,就是注册i2c设备,然后通过一个任务队列,每隔delay时间向上报x,y,z数据.
在drivers/input/sensors/accel/bma2x2.c中
module_init(BMA2X2_init);

static int __init BMA2X2_init(void)
{
    //注册了一个i2c设备驱动
    return i2c_add_driver(&bma2x2_driver);
}

在probe函数中

static int bma2x2_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    int err = 0;
    int tempvalue;
    unsigned char tmp_chip_id;
    struct input_dev *dev;

    struct bma2x2_data *data = kzalloc(sizeof(struct bma2x2_data), GFP_KERNEL);
    //获取设备的具体型号
    tempvalue = i2c_smbus_read_word_data(client, BMA2X2_CHIP_ID_REG);
    tmp_chip_id = tempvalue&0x00ff;
    switch (tmp_chip_id) {
    case BMA255_CHIP_ID:
        data->sensor_type = BMA255_TYPE;
        break;
    case BMA250E_CHIP_ID:
        data->sensor_type = BMA250E_TYPE;
        break;
    case BMA222E_CHIP_ID:
        data->sensor_type = BMA222E_TYPE;
        break;
    case BMA280_CHIP_ID:
        data->sensor_type = BMA280_TYPE;
        break;
    default:
        data->sensor_type = -1;
    }

    if (data->sensor_type != -1) {
        data->chip_id = tmp_chip_id;
    } else{
        err = -ENODEV;
        goto kfree_exit;
    }
    i2c_set_clientdata(client, data);
    data->bma2x2_client = client;
    mutex_init(&data->value_mutex);
    mutex_init(&data->mode_mutex);
    mutex_init(&data->enable_mutex);
    bma2x2_set_bandwidth(client, BMA2X2_BW_SET);
    bma2x2_set_range(client, BMA2X2_RANGE_SET);
    bma2x2_set_Int_Enable(client, 8, 1);
    bma2x2_set_Int_Enable(client, 10, 1);
    bma2x2_set_Int_Enable(client, 11, 1);

    INIT_DELAYED_WORK(&data->work, bma2x2_work_func);
    atomic_set(&data->delay, BMA2X2_MAX_DELAY);       //将delay设为8ms
    atomic_set(&data->enable, 0);

    dev = input_allocate_device();
    dev->name = SENSOR_NAME;
    dev->id.bustype = BUS_I2C;

    input_set_capability(dev, EV_REL, LOW_G_INTERRUPT);
    input_set_capability(dev, EV_REL, HIGH_G_INTERRUPT);
    input_set_capability(dev, EV_REL, SLOP_INTERRUPT);
    input_set_capability(dev, EV_REL, DOUBLE_TAP_INTERRUPT);
    input_set_capability(dev, EV_REL, SINGLE_TAP_INTERRUPT);
    input_set_capability(dev, EV_ABS, ORIENT_INTERRUPT);
    input_set_capability(dev, EV_ABS, FLAT_INTERRUPT);
    input_set_abs_params(dev, ABS_X, ABSMIN, ABSMAX, 0, 0);
    input_set_abs_params(dev, ABS_Y, ABSMIN, ABSMAX, 0, 0);
    input_set_abs_params(dev, ABS_Z, ABSMIN, ABSMAX, 0, 0);

    input_set_drvdata(dev, data);

    input_register_device(dev);

    data->input = dev;

    schedule_work(&data->work);

    return 0;
}

static int bma2x2_read_accel_xyz(struct i2c_client *client, signed char sensor_type, struct bma2x2acc *acc)
{
    int comres = 0;
    unsigned char data[6];
    comres = bma2x2_smbus_read_byte_block(client, BMA2X2_ACC_X12_LSB__REG, data, 6);
    acc->x = (data[1]<<8)|data[0];
    acc->y = (data[3]<<8)|data[2];
    acc->z = (data[5]<<8)|data[4];

    return comres;
}

static void bma2x2_work_func(struct work_struct *work)
{
    struct bma2x2_data *bma2x2 = container_of((struct delayed_work *)work, struct bma2x2_data, work);
    static struct bma2x2acc acc;
    unsigned long delay = msecs_to_jiffies(atomic_read(&bma2x2->delay));
    bma2x2_read_accel_xyz(bma2x2->bma2x2_client, bma2x2->sensor_type, &acc);
    input_report_abs(bma2x2->input, ABS_X, -acc.y);
    input_report_abs(bma2x2->input, ABS_Y, acc.x);
    input_report_abs(bma2x2->input, ABS_Z, acc.z);
    input_sync(bma2x2->input);
    schedule_delayed_work(&bma2x2->work, delay);     //每隔8ms上报一次
}