一，前言

学习了陀螺仪及加速度计的原理及了解了MPU6500的寄存器手册及六轴陀螺仪模块的引脚定义后，就进入了驱动框架设计及驱动具体细节设计。MPU6500的驱动代码及测试代码已上我的gitee工程16

二，测量理论及驱动框架设计

此六轴可测量3类传感器，加速度计，陀螺仪和温度。直接可以从寄存器读取。
加速度计输出值就是重力加速度g为单位，平放的话会有一个为1g，其它2个方向为0。陀螺仪就是转角速度，围绕某个轴转动就有速度值，否则为0。温度为环境温度。至于芯片中可以直接烧录黑盒DMP固件，这个需要移植，我就不移植了，因为我之后想自己做一个卡尔曼滤波算法，多传感器融合等。现在的linux驱动就是采用input子系统周期上报通过i2c读寄存器的数据，然后APP测试代码中将AD值转为带单位的值而已。AD为16位的，然后灵敏度自己通过设置测量范围后看有计算出，这个就不多说了。

三，硬件连线

就连接了5根线，I2C用了4根。ADD接地，所以设备地址为0x68，若接高电平3,3v，地址为0x69。

image.png

修改DTB

image.png

四， 遇到的问题

1. 编译遇到input_register_polled_device未定义
   o文件已经生成，说明link文件出错，那么就说明polled dev那个c函数没有被编译，搜索到源码后，在makefile中找到对应的配置项CONFIG_INPUT_POLLDEV设置为true，然后编译内核。然后重新编译我的外部模块，能正常编译出ko文件。
2. 在板子/dev/input/目录下只有mice 没有event0目录
   答案为内核需要配置CONFIG_INPUT_EVDEV=y
   当然若要修改源码来固定event，方法如下
   https://blog.csdn.net/savage_sdj/article/details/25278111

五，测试通过

image.png

ACC的值和实际方向是反的。先平放，可以看到加速度计z=1（就是2g-1g=1g），然后沿x轴转90度看到y等于-1，然后再转90度，看到acc的x为1，最后再平放绕z轴转，看到z轴的陀螺仪角度变化最大。

# insmod apple6500_dev3.ko 
[  169.347794] input: apple6500sensor as /devices/platform/ocp/48000000.interconnect/48000000.interconnect:segment@100000/4819c000.target-module/4819c000.i2c/i2c-2/2-0068/input/input1
# ./ev2
ACC x=0.37 y=0.17 z=0.92 
Gyro x=-0.01 y=0.00 z=0.01 
temp=18.48 
ACC x=0.37 y=0.17 z=0.92 
Gyro x=-0.01 y=0.00 temp=18.49 
ACC x=0.37 y=0.17 z=0.91 
Gyro x=-0.01 y=-0.00 temp=18.46 
ACC x=0.37 Gyro x=-0.01 y=-0.00 z=0.01 
temp=18.47 
ACC x=0.37 y=0.17 z=0.92 
Gyro x=-0.01 y=-0.00 z=0.01 
temp=18.48 
ACC x=0.37 y=0.17 z=0.92 
y=0.00 temp=18.47 
y=0.17 z=0.92 
Gyro x=-0.01 y=-0.00 z=0.01 
ACC x=0.37 y=0.17 z=0.92 
Gyro x=-0.01 z=0.01 
ACC x=0.37 y=0.15 z=0.92 
Gyro x=-0.02 y=0.00 z=0.02 
temp=18.47 
ACC x=0.37 y=0.16 z=0.92 
Gyro x=-0.01 y=0.00 z=0.01 
temp=18.46 
ACC x=0.37 y=0.17 z=0.91 
Gyro x=-0.00 y=-0.00 z=0.01 
temp=18.47 
ACC x=0.37 y=0.16 z=0.92 
Gyro x=-0.01 y=-0.00 z=0.01 
temp=18.46 
ACC x=0.37 y=0.16 z=0.92 
Gyro x=-0.01 temp=18.48 
ACC x=0.38 y=0.15 z=0.92 
Gyro x=-0.39 y=0.11 z=0.74 
ACC x=0.47 y=-0.13 z=0.88 
Gyro x=-1.00 y=0.55 z=0.22 
temp=18.47 
ACC x=0.22 y=-0.08 z=0.99 
Gyro x=-0.33 y=0.42 z=0.13 
temp=18.48 
ACC x=0.20 y=-0.15 z=0.98 
Gyro x=-0.11 y=-0.42 z=-0.43 
temp=18.48 
ACC x=0.21 y=-0.10 z=0.98 
Gyro x=-0.42 y=1.21 z=-0.52 
temp=18.48 
ACC x=-0.07 y=-0.16 z=0.96 
Gyro x=-2.41 y=0.20 z=-0.07 
temp=18.49 
ACC x=0.06 y=-0.80 z=0.57 
Gyro x=-3.56 y=-0.96 z=0.44 
temp=18.48 
ACC x=0.05 y=-0.98 z=0.29 
Gyro x=-0.53 y=0.04 z=0.03 
temp=18.48 
ACC x=0.02 y=-1.01 z=0.22 
Gyro x=-0.43 y=0.01 z=-0.00 
temp=18.49 
ACC x=0.03 y=-1.01 z=0.21 
Gyro x=-0.10 y=0.08 z=0.01 
temp=18.50 
ACC x=0.03 y=-1.01 z=0.16 
Gyro x=-0.04 y=-0.01 z=-0.02 
temp=18.49 
ACC x=0.02 z=0.15 
Gyro x=-0.04 y=-0.02 z=0.01 
temp=18.48 
ACC x=0.02 y=-1.02 z=0.15 
Gyro x=-0.01 y=0.01 z=0.03 
temp=18.49 
ACC x=0.02 y=-1.02 z=0.14 
Gyro x=-0.02 y=-0.00 z=0.00 
temp=18.50 
ACC x=0.03 y=-1.02 z=0.14 
Gyro x=-0.04 y=-0.00 z=-0.00 
temp=18.50 
ACC x=0.03 y=-1.01 z=0.14 
Gyro x=-0.03 y=-0.01 z=-0.02 
temp=18.50 
ACC x=0.02 y=-1.02 z=0.14 
Gyro x=0.01 y=0.00 z=-0.00 
temp=18.51 
ACC x=0.04 y=-1.02 z=0.14 
Gyro x=0.03 y=-0.06 z=-0.03 
temp=18.50 
ACC x=0.02 y=-1.01 z=0.19 
Gyro x=0.35 y=0.08 z=-0.01 
temp=18.51 
ACC x=0.09 y=-0.96 z=0.33 
Gyro x=0.68 y=0.25 z=-0.32 
temp=18.51 
ACC x=0.54 y=-0.65 z=0.56 
Gyro x=1.68 y=-0.30 z=-5.53 
temp=18.50 
ACC x=0.87 y=-0.32 z=0.57 
Gyro x=-0.12 y=-0.06 z=-0.57 
ACC x=0.88 y=0.02 z=0.49 
Gyro x=-0.28 y=-0.35 z=-0.58 
ACC x=0.87 y=0.10 z=0.32 
Gyro x=-0.24 y=-0.41 z=-0.20 
temp=18.50 
ACC x=0.99 y=0.09 z=0.22 
Gyro x=0.03 y=-0.73 z=0.36 
temp=18.50 
ACC x=0.97 y=0.08 z=0.04 
Gyro x=0.03 y=-0.29 z=-0.06 
ACC x=1.01 y=-0.13 z=0.29 
Gyro x=-0.03 y=-0.05 z=0.02 
temp=18.49 
ACC x=1.00 y=-0.02 z=0.04 
Gyro x=0.06 y=-0.18 z=-0.03 
temp=18.51 
ACC x=1.00 y=-0.01 z=0.04 
Gyro x=-0.01 y=0.01 z=0.01 
ACC x=1.00 y=-0.01 z=0.05 
Gyro x=-0.01 y=-0.00 z=0.01 
ACC x=1.00 y=-0.02 z=0.04 
Gyro x=-0.00 y=0.00 z=0.00 
temp=18.50 
ACC x=1.00 z=0.04 
Gyro x=-0.01 y=0.00 z=0.01 
temp=18.49 
ACC x=1.00 y=-0.01 z=0.04 
Gyro x=-0.01 y=0.00 z=0.01 
temp=18.50 
ACC x=1.00 y=-0.02 z=0.04 
Gyro x=-0.01 z=0.00 
temp=18.51 
ACC x=1.00 y=-0.01 z=0.05 
y=0.01 z=0.01 
temp=18.51 
ACC x=1.00 y=-0.02 z=0.04 
Gyro x=-0.00 y=-0.01 z=0.01 
temp=18.51 
ACC x=1.00 y=-0.02 z=0.05 
Gyro x=-0.01 y=0.01 z=0.01 
temp=18.50 
ACC x=1.00 y=-0.01 z=0.05 
Gyro x=-0.01 y=-0.01 z=0.00 
temp=18.50 
ACC x=1.00 y=-0.02 z=0.04 
y=-0.01 ACC x=1.00 y=-0.01 z=0.04 
y=-0.00 z=0.01 
temp=18.51 
ACC x=1.00 y=-0.01 z=0.04 
Gyro x=-0.01 y=0.02 z=0.01 
ACC x=1.00 y=-0.02 z=0.04 
Gyro x=-0.01 y=-0.00 z=0.01 
temp=18.49 
ACC x=1.00 y=-0.02 z=0.06 
Gyro x=-0.00 y=0.03 z=0.00 
temp=18.51 
ACC x=0.99 y=-0.03 z=0.06 
Gyro x=-0.06 y=0.13 z=0.04 
temp=18.52 
ACC x=0.93 y=-0.14 z=0.28 
Gyro x=0.59 y=2.22 z=1.16 
temp=18.51 
ACC x=0.39 y=-0.06 z=1.09 
Gyro x=1.99 y=2.39 z=2.87 
temp=18.50 
ACC x=-0.01 y=0.07 z=1.04 
Gyro x=0.67 y=2.11 z=4.21 
temp=18.52 
ACC x=0.06 y=0.08 z=0.97 
Gyro x=-1.58 y=0.68 z=0.27 
temp=18.50 
ACC x=-0.18 y=0.07 z=1.02 
Gyro x=-0.07 y=-0.13 z=0.01 
temp=18.50 
ACC x=-0.06 y=0.16 z=0.94 
Gyro x=-0.03 y=0.34 z=0.33 
ACC x=-0.05 y=0.01 z=0.90 
Gyro x=-0.13 y=0.08 z=0.04 
temp=18.50 
ACC x=-0.07 y=-0.05 z=1.02 
Gyro x=-0.73 y=0.87 z=-0.06 
temp=18.50 
ACC x=-0.07 y=-0.06 z=1.00 
Gyro x=0.07 y=0.17 z=-0.33 
temp=18.49 
ACC x=-0.04 y=0.00 z=0.99 
Gyro x=0.40 y=-0.70 z=-2.57 
temp=18.50 
ACC x=0.02 y=0.04 z=1.00 
Gyro x=-0.13 y=-0.71 z=-4.19 
ACC x=0.09 y=0.29 z=0.89 
Gyro x=-0.19 y=0.30 z=-4.15 
temp=18.51 
ACC x=-0.08 y=-0.02 z=1.01 
Gyro x=0.01 y=0.08 z=0.05 
temp=18.50 
ACC x=-0.15 y=-0.12 z=1.06 
Gyro x=-0.83 y=0.93 z=6.51 
temp=18.49 
ACC x=-0.02 y=-0.22 z=1.01 
Gyro x=-1.78 y=1.21 z=8.87 
temp=18.50 
ACC x=-0.11 y=-0.05 z=1.02 
Gyro x=0.09 y=0.05 z=0.68 
temp=18.49 
ACC x=-0.32 y=0.04 z=0.79 
Gyro x=1.16 y=-0.84 z=-7.30 
temp=18.50 
ACC x=-0.12 y=0.22 z=0.94 
Gyro x=0.64 y=0.01 z=-7.44 
temp=18.50 
ACC x=-0.18 y=0.11 z=0.89 
Gyro x=-1.13 y=-0.98 z=-1.77 
temp=18.49 
ACC x=0.11 y=0.03 z=0.97 
Gyro x=-0.14 y=-1.43 z=-2.37 
temp=18.50 
ACC x=-0.12 y=0.12 z=1.28 
Gyro x=0.04 y=0.20 z=1.34 
temp=18.51 
ACC x=-0.08 y=0.09 z=0.97 
Gyro x=0.29 y=0.29 z=1.82 
temp=18.50 
ACC x=-0.14 y=-0.02 z=0.96 
Gyro x=-0.69 y=-0.09 z=6.22 
temp=18.49 
ACC x=-0.11 y=-0.07 z=1.02 
Gyro x=-0.61 y=1.33 z=7.63 
temp=18.50 
ACC x=-0.06 y=-0.07 z=0.99 
Gyro x=-0.17 y=-1.20 z=1.06 
ACC x=-0.23 y=-0.01 z=0.94 
Gyro x=0.42 y=0.18 z=-2.55 
temp=18.49 
ACC x=-0.16 y=0.05 z=0.96 
Gyro x=-0.00 y=-0.07 z=-5.65 
ACC x=0.16 y=-0.11 z=1.01 
Gyro x=0.53 y=0.99 z=-4.74 
temp=18.51 
ACC x=0.04 y=-0.05 z=1.05 
Gyro x=0.49 y=-0.24 z=-4.24 
temp=18.51 
ACC x=0.16 y=0.41 z=1.01 
Gyro x=-0.12 y=0.01 z=1.63 
temp=18.51 
ACC x=-0.06 y=-0.23 z=0.99 
Gyro x=-0.61 y=0.08 z=7.06 
temp=18.50 
ACC x=0.45 y=0.41 z=0.97 
Gyro x=-1.62 y=0.98 z=9.36 
temp=18.51 
ACC x=0.05 y=0.01 z=1.03 
Gyro x=0.60 y=-2.72 z=-5.54 
temp=18.49 
ACC x=0.18 y=-0.04 z=1.20 
Gyro x=-0.68 y=1.03 z=-0.28 
temp=18.50 

六，学习到的内容

1.input_polled_dev，设置一个周期后内核对按此周期定时调用poll函数。这样就省去了自定hrtimer定时器。

2.smbus兼容i2c，所以用i2c_smbus_read_i2c_block_data接口比用i2c接口简单高效。但是smbus最大的clock频率为100KHz，而i2c可以支持400KHz或2MHz。不要紧反正是最底层的函数，修改起来也容易，先用下新的函数。

3. input子系统的API。input子系统中使用i2c总线驱动的API。

七，驱动源码

之后再看看相关锁是否要添加，暂时都没有加，另外电源管理相关也没有添加。MPU6500的中断脚其实也比较有作用的，由于现在app测试代码中只有通过公式进行AD转换，没有其它功能，所以驱动也没加INT相关，之后要做某些应用的话，考虑加入。另外，对MPU6500初始化写的也比较简单，没有添加很多配置函数进行灵活设置，这毕竟是第一版，先测试下基本功能。另外主要目的是学习linux驱动框架，而不是学习这个MPU6500芯片，哈哈~

/**********************************************************************************
Copyright (C), by AppleCai
Project                      : Study Kernel
Description                  : BSP level for MPU6500
CPU and Compiler             : AM335x,ARM-LINIX-GCC
|----------------------------------------------------------------------------------
|               R E V I S I O N   H I S T O R Y
|----------------------------------------------------------------------------------
| Date        Version  Author   Description
| --------    -------  ------   ---------------------------------------------------
| 2020-12-08  1.0.0    AppleCai MPU6500_001: Initial release version just add frame
| 2020-12-09  1.0.1    AppleCai MPU6500_002: add WMI reg and I2C DTB
| 2020-12-10  1.0.2    AppleCai MPU6500_003: add Initial reg and report functions
| 2020-12-11  1.0.3    AppleCai MPU6500_004: Optimize code structure
**********************************************************************************/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/input-polldev.h>
#include <linux/of_device.h>

#define APPLE6500_DRV_NAME  "apple6500sensor"

#define POLL_INTERVAL           200
#define POLL_INTERVAL_MAX       500

/* bit op */
#define VAL_SIT_BIT(n,addr)        *addr |= (1<<n)
#define VAL_CLEAR_BIT(n,addr)      *addr &= ~(1<<n)
#define VAL_CHANGE_BIT(n,addr)     *addr ^= (1<<n)
#define VAL_TEST_BIT(n,addr)       *addr &= (1<<n)

struct apple6500_chip_reg {
    /* regs */
    char who_am_i;
    char pwr_mgmt_1;
    char pwr_mgmt_2;
    char smplrt_div;
    char sensor_config;
    char accel_config;
    char accel_config2;
    char accel_xout_h;
    char temp_out_h;
    char gyro_xout_h;
    char gyro_config;
    char signal_path_reset;
};
static const struct apple6500_chip_reg chipregs={
    /* reg addr */
    .who_am_i= 117,
    .pwr_mgmt_1= 107,
    .pwr_mgmt_2= 108,
    .smplrt_div= 25,
    .sensor_config= 26,
    .gyro_config= 27,
    .accel_config= 28,
    .accel_config2= 29,
    .accel_xout_h= 59,
    .temp_out_h= 65,
    .gyro_xout_h= 67,
    .signal_path_reset= 104,
};

struct apple6500_chip_config{
    char chip_id;
    char chip_enable_sensor;
    char chip_frequency_acc;
    char chip_frequency_gyro;
    char chip_frequency_DIV;
    char chip_reset;
    char chip_sensitivity_acc;
    char chip_sensitivity_gyro; 
    char chip_selectedclock;
};
struct apple6500;
struct apple6500_transfer_func {
    int (*read) (struct apple6500 *m, unsigned off);
    int (*write) (struct apple6500 *m, unsigned off, unsigned char v);
    int (*readblock)(struct apple6500 *m, unsigned off,unsigned char *buf, size_t size);
};

/* apple6500 status */
struct apple6500 {
    struct device   *dev;
    struct input_polled_dev *idev;
    const struct apple6500_chip_reg *regs;
    struct apple6500_chip_config cfgs;
    const struct apple6500_transfer_func *tf;
};

static int apple6500_read(struct apple6500 *m, unsigned off)
{
    //struct i2c_client *c = m->client;
    struct i2c_client *c = to_i2c_client(m->dev);
    int ret;

    ret = i2c_smbus_read_byte_data(c, off);
    if (ret < 0)
        dev_err(&c->dev,
            "failed to read register 0x%02x, error %d\n",
            off, ret);

    return ret;
}

static int apple6500_write(struct apple6500 *m, unsigned off, unsigned char v)
{
    //struct i2c_client *c = m->client;
    struct i2c_client *c = to_i2c_client(m->dev);
    int error;

    error = i2c_smbus_write_byte_data(c, off, v);
    if (error < 0) {
        dev_err(&c->dev,
            "failed to write to register 0x%02x, error %d\n",
            off, error);
        return error;
    }

    return 0;
}

static int apple6500_read_block(struct apple6500 *m, unsigned off,unsigned char *buf, size_t size)
{
    //struct i2c_client *c = m->client;
    struct i2c_client *c = to_i2c_client(m->dev);
    int err;

    err = i2c_smbus_read_i2c_block_data(c, off, size, buf);
    if (err < 0) {
        dev_err(&c->dev,
            "failed to read block data error %d\n", err);
        return err;
    }

    return 0;
}
static const struct apple6500_transfer_func apple6500_tf_i2c = {
    .write = apple6500_write,
    .read = apple6500_read,
    .readblock = apple6500_read_block
};
static void apple6500_poll(struct input_polled_dev *dev)
{
    struct apple6500 *m = dev->private;

    int ax, ay, az,gx,gy,gz,temp;
    int ret;
    u8 buf[14];

    ret = m->tf->readblock(m, m->regs->accel_xout_h, buf, sizeof(buf));
    if (ret < 0)
    {
        dev_err(m->dev, "polling error\n");
        return;
    }
    ax = ( buf[0] << 8 ) | buf[1];
    ay = ( buf[2] << 8 ) | buf[3];
    az = ( buf[4] << 8 ) | buf[5];
    temp = ( buf[6] << 8 ) | buf[7];
    gx = ( buf[8] << 8 ) | buf[9];
    gy = ( buf[10] << 8 ) | buf[11];
    gz = ( buf[12] << 8 ) | buf[13];

    input_report_abs(dev->input, ABS_X, ax);
    input_report_abs(dev->input, ABS_Y, ay);
    input_report_abs(dev->input, ABS_Z, az);
    input_report_abs(dev->input, ABS_RX, gx);
    input_report_abs(dev->input, ABS_RY, gy);
    input_report_abs(dev->input, ABS_RZ, gz);
    input_report_abs(dev->input, ABS_MISC, temp);//Temperature = 36.53 + regval/340
    input_sync(dev->input);
}
static void apple6500_Init_reg(struct apple6500_chip_config * cfgs)
{
    cfgs->chip_id = 0x70; // id for MPU6500
    cfgs->chip_enable_sensor = 0; // enable all
    cfgs->chip_frequency_acc = 4; // 50Hz/2=25Hz then select 20Hz
    cfgs->chip_frequency_DIV = 19; // 1000/(19+1) = 50Hz clock for acc
    cfgs->chip_frequency_gyro = 4; // 1K 20Hz,due to FCHOICE_B=0
    cfgs->chip_reset = 1<<7; // true 
    cfgs->chip_sensitivity_acc = 0; // 65536/4 = 16384 LBS/s
    cfgs->chip_sensitivity_gyro = 3<<3; // 65536/4000 = 16.384 LBS/s
    cfgs->chip_selectedclock = 1; // PLL with axis 
}
static int apple6500_CheckId(struct apple6500 *m)
{
    int IdNum = 0;
    IdNum = m->tf->read(m, m->regs->who_am_i);
    if(m->cfgs.chip_id != IdNum)
    {
        dev_err(m->dev, "Not found MPU6500\n");
        return -ENXIO;
    }   
    return 0;
}

static int apple6500_ResetChipAndSelectClock(struct apple6500 *m)
{
    int err = 0;
    int val = 0;
    val = m->cfgs.chip_reset+m->cfgs.chip_selectedclock;
    err = m->tf->write(m, m->regs->pwr_mgmt_1,val);
    if(err)
    {
        dev_err(m->dev, "reset command error\n");
    }   
    return err;
}

static int apple6500_EnableSensor(struct apple6500 *m)
{
    int err = 0;
    err = m->tf->write(m, m->regs->pwr_mgmt_2,m->cfgs.chip_enable_sensor);
    if(err)
    {
        dev_err(m->dev, "enable command error\n");
    }   
    return err;
}

static int apple6500_SetACCSamplerate(struct apple6500 *m)
{
    int err = 0;
    err = m->tf->write(m, m->regs->accel_config2,m->cfgs.chip_frequency_acc);
    if(err)
    {
        dev_err(m->dev, "set acc bandwidths error\n");
    }   
    err = m->tf->write(m, m->regs->smplrt_div,m->cfgs.chip_frequency_DIV);
    if(err)
    {
        dev_err(m->dev, "set acc clock division error\n");
    }   
    return err;
}

static int apple6500_SetGyroSamplerate(struct apple6500 *m)
{
    int err = 0;
    err = m->tf->write(m, m->regs->sensor_config,m->cfgs.chip_frequency_gyro);
    if(err)
    {
        dev_err(m->dev, "set gyro bandwidths error\n");
    }   
    return err;
}

static int apple6500_SetAccSensitivity(struct apple6500 *m)
{
    int err = 0;
    err = m->tf->write(m, m->regs->accel_config,m->cfgs.chip_sensitivity_acc);
    if(err)
    {
        dev_err(m->dev, "set acc sensitivity error\n");
    }   
    return err;
}

static int apple6500_SetGyroSensitivity(struct apple6500 *m)
{
    int err = 0;
    err = m->tf->write(m, m->regs->gyro_config,m->cfgs.chip_sensitivity_gyro);
    if(err)
    {
        dev_err(m->dev, "set gyro sensitivity error\n");
    }   
    return err;
}

static int apple6500_Init(struct apple6500 *m)
{
    
    int ret = 0;
    /* load default configuration value */
    apple6500_Init_reg(&m->cfgs);
    /* check id */
    ret = apple6500_CheckId(m);
    /* set reset chip and select clock */
    ret = apple6500_ResetChipAndSelectClock(m);
    /* enable acc and gyro */
    ret = apple6500_EnableSensor(m);
    /* set sample rate and bandwith for acc*/
    ret = apple6500_SetACCSamplerate(m);
    /* set sample rate and bandwith for gyro*/
    ret = apple6500_SetGyroSamplerate(m);   
    /* set sensitivity for acc*/
    ret = apple6500_SetAccSensitivity(m);   
    /* set sensitivity for gyro*/
    ret = apple6500_SetGyroSensitivity(m);
    if (ret < 0)
    {
        dev_err(m->dev,"init error\n");
        return -1;
    }
    return ret;
}

/* Initialize the APPLE6500 chip */
static void apple6500_open(struct input_polled_dev *dev)
{
    int ret = 0;
    struct apple6500 *m = dev->private;
    ret = apple6500_Init(m);
    if (ret < 0)
    {
        dev_err(m->dev, "apple6500 initialization failed\n");
        return;
    }
}

static void apple6500_close(struct input_polled_dev *dev)
{

    //struct apple6500 *m = dev->private;
    //int ret = 0;
    /* sleep */
    //ret = m->tf->write(m, APPLE6500_PWR_REG107,APPLE6500_PWR_SLEEP);
    //if (ret < 0)
    //  return;
}
static const struct of_device_id apple6500_dt_ids[] = {
    { .compatible = "applecai,apple6500", .data = &chipregs},
    { /* sentinel */ }
};
/*
 * I2C init/probing/exit functions
 */
static int apple6500_i2c_probe(struct i2c_client *c,
             const struct i2c_device_id *id)
{
    struct input_polled_dev *idev;
    struct apple6500 *m;
    int err;
    const struct of_device_id *match;
    /* Check basic functionality */
    err = i2c_check_functionality(c->adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA|
                                  I2C_FUNC_SMBUS_READ_BYTE_DATA|
                                  I2C_FUNC_SMBUS_READ_I2C_BLOCK);
    if (!err) {
        dev_err(&c->dev, "%s adapter not supported\n",
            dev_driver_string(&c->adapter->dev));
        return -ENODEV;
    }
    
    match = of_match_node(apple6500_dt_ids,c->dev.of_node);
    if (!match)
    {
        dev_err(&c->dev, "No such device or address.\n");
        return -ENXIO;
    }
    m = devm_kzalloc(&c->dev, sizeof(*m), GFP_KERNEL);
    if (!m)
        return -ENOMEM;

    idev = devm_input_allocate_polled_device(&c->dev);
    if (!idev)
        return -ENOMEM;

    //m->client = c;
    m->dev = &c->dev;
    m->idev = idev;
    m->regs = match->data;
    m->tf = &apple6500_tf_i2c;
    i2c_set_clientdata(c, m);
    idev->private       = m;
    idev->input->name   = APPLE6500_DRV_NAME;
    idev->input->id.bustype = BUS_I2C;
    idev->input->id.vendor = 0xABCD;
    idev->input->id.product = 0x0001;
    idev->input->id.version = 0x0100;
    idev->poll      = apple6500_poll;
    idev->poll_interval = POLL_INTERVAL;
    idev->poll_interval_max = POLL_INTERVAL_MAX;
    idev->open      = apple6500_open;
    idev->close     = apple6500_close;

    __set_bit(EV_ABS, idev->input->evbit);
    input_set_abs_params(idev->input, ABS_X, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_Y, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_Z, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_RX, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_RY, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_RZ, -32768, 32767, 0, 0);
    input_set_abs_params(idev->input, ABS_MISC, -32768, 32767, 0, 0);

    err = input_register_polled_device(idev);
    if (err) {
        input_unregister_polled_device(idev);
        dev_err(&c->dev, "failed to register polled input device\n");
        goto out;
    }
    return 0;
out:
    input_unregister_polled_device(idev);
    return err;
}

static int apple6500_i2c_remove(struct i2c_client *c)
{
    struct apple6500 *m = i2c_get_clientdata(c);
    //disable sensor
    input_unregister_polled_device(m->idev);
    input_free_polled_device(m->idev);
    dev_info(m->dev, "%s: removed\n", APPLE6500_DRV_NAME);
    kfree(m);
    return 0;
}


MODULE_DEVICE_TABLE(of, apple6500_dt_ids);

static struct i2c_driver apple6500_driver = {
    .driver = {
        .name   = APPLE6500_DRV_NAME,
        .of_match_table = apple6500_dt_ids,
    },
    .probe      = apple6500_i2c_probe,
    .remove   = apple6500_i2c_remove,
};

module_i2c_driver(apple6500_driver);

MODULE_AUTHOR("AppleCai");
MODULE_DESCRIPTION("APPLE6500 Acceler and Gyro Driver");
MODULE_LICENSE("GPL");