MPU6050

2. MPU6050模块 — [野火]STM32模块例程介绍文档
https://doc.embedfire.com/module/module_tutorial/zh/latest/Module_Manual/iic_class/mpu6050.html

Linux驱动 = 硬件操作 + 驱动框架
所以对于MPU6050的原理和驱动代码实现参考单片机的即可。

MPU6050驱动实现

设备树

设备树参考： 可参考NXP公板的设备树的I2C节点

&i2c1 {clock-frequency = <100000>;pinctrl-names = "default";pinctrl-0 = <&pinctrl_i2c1>;status = "okay";...mag3110@e {compatible = "fsl,mag3110";reg = <0xe>;position = <2>;};fxls8471@1e {compatible = "fsl,fxls8471";reg = <0x1e>;position = <0>;interrupt-parent = <&gpio5>;interrupts = <0 8>;};
};

mag3110和fxls8471是NXP公板上挂在I2C1的两个芯片

编写设备树：
在imx6ull-mmc-npi.dts文件中添加节点：

&i2c1 { clock-frequency = <100000>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_i2c1>;   status = "okay"; #address-cells = <1>;#size-cells = <0>;/* 设备树修改查看是否修改成功，查看内核目录/sys/bus/i2c/devices/看是否存在0x1E地址的设备 */mpu6050@68 {compatible = "xgj,mpu6050";status = "okay"; reg = <0x68>;interrupt-parent = <&gpio5>;interrupts = <0 IRQ_TYPE_LEVEL_LOW>;};
};

因为mpu6050芯片是挂载在i2c1，将其设备节点追加在i2c节点下

compatible ，驱动根据该值和设备树进行匹配
reg， i2c设备地址
interrupt-parent，芯片中断脚在哪个中断控制器下
interrupts ,中断引脚号0和IRQ_TYPE_LEVEL_LOW低电平触发

设备树编译：

ares@ubuntu:~/work/ebf_linux_kernel-ebf_4.19.35_imx6ul$ cat make_dtb.sh
#!/bin/shmake ARCH=arm -j4 CROSS_COMPILE=arm-linux-gnueabihf- dtbs

将设备树拷贝系统目录：

debian@npi:~/nfs_root/driver$ cat cp_dtb_to_linux.sh
#!/bin/shsudo cp imx6ull-mmc-npi.dtb /usr/lib/linux-image-4.19.35-carp-imx6/

/usr/lib/linux-image-4.19.35-carp-imx6/ ，系统存放设备树的目录

重启系统设备树生效：

sudo reboot

通过查看系统目录 /sys/firmware/devicetree/base/ 看是否存在mpu6050的设备树节点判定设备树是否生效

驱动编写

1、MPU6050硬件操作

这部分内容和单片机程序差不多。

mpu6050_def.h ：

#ifndef _MPU6050_DEF_H_
#define _MPU6050_DEF_H_typedef unsigned char   uint8_t;/* register define */
#define MPU6050_SMPLRT_DIV                                  0x19/* */
#define MPU6050_CONFIG                                      0x1A
#define MPU6050_GYRO_CONFIG                                 0x1B
#define MPU6050_ACCEL_CONFIG                                0x1C
#define MPU6050_ACCEL_XOUT_H                                0x3B
#define MPU6050_ACCEL_XOUT_L                                0x3C
#define MPU6050_ACCEL_YOUT_H                                0x3D
#define MPU6050_ACCEL_YOUT_L                                0x3E
#define MPU6050_ACCEL_ZOUT_H                                0x3F
#define MPU6050_ACCEL_ZOUT_L                                0x40
#define MPU6050_TEMP_OUT_H                                  0x41
#define MPU6050_TEMP_OUT_L                                  0x42
#define MPU6050_GYRO_XOUT_H                                 0x43
#define MPU6050_GYRO_XOUT_L                                 0x44
#define MPU6050_GYRO_YOUT_H                                 0x45
#define MPU6050_GYRO_YOUT_L                                 0x46
#define MPU6050_GYRO_ZOUT_H                                 0x47
#define MPU6050_GYRO_ZOUT_L                                 0x48
#define MPU6050_PWR_MGMT_1                                  0x6B/* power managemnt register */
#define MPU6050_WHO_AM_I                                    0x75/* default value :  IIC addr 0x68 *//* interrupt status register */
#define MPU6050_INT_STATUS                                  0x3A
#define MPU6050_INT_ENABLE                                  0x38
#define MPU6050_INT_PIN_CFG                                 0x37// #define I2C_RETRIES                                 0x0701
// #define I2C_TIMEOUT                                 0x0702
// #define I2C_SLAVE                                   0x0703             //IIC从器件的地址设置
// #define I2C_BUS_MODE                                0x0780// #define MPU6050_SlaveAddress                                  0xD0
// #define MPU6050_IIC_ADDR                                      0x68                  //MPU6050 IIC Addressstruct mpu6050_accel {short x;short y;short z;
};struct mpu6050_gyro {short x;short y;short z;
};struct mpu6050_data {struct mpu6050_accel accel;struct mpu6050_gyro gyro;
};#endif /* _MPU6050_DEF_H_ */


static int mpu6050_i2c_write_reg(struct i2c_client *client, uint8_t reg_addr, uint8_t data)
{int ret = 0;uint8_t w_buf[2];struct i2c_msg msg;w_buf[0] = reg_addr;w_buf[1] = data;msg.addr = client->addr;msg.buf = w_buf;msg.flags = 0; /* I2C direction ： write */msg.len = sizeof(w_buf);ret = i2c_transfer(client->adapter, &msg, 1);if (ret < 0)return ret;else if (ret != 1)return -EIO;return 0;
}static int mpu6050_i2c_read_reg(struct i2c_client *client, uint8_t reg_addr, uint8_t *data)
{int ret = 0;struct i2c_msg msgs[2];msgs[0].addr = client->addr;msgs[0].buf = &reg_addr; /* send regsiter */msgs[0].flags = 0;       /* I2C direction ： write */msgs[0].len = 1;msgs[1].addr = client->addr;msgs[1].buf = data;       /* 读取寄存器数据 */msgs[1].flags = I2C_M_RD; /* I2C direction ： read */msgs[1].len = 1;ret = i2c_transfer(client->adapter, msgs, 2); /* */if (ret < 0)return ret;else if (ret != 2)return -EIO;return 0;
}static int mpu6050_init(void)
{uint8_t reg_val = 0;int ret = 0;/* 解除休眠状态 */ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_PWR_MGMT_1, 0x00); /*  *//*  陀螺仪采样频率输出设置 */ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_SMPLRT_DIV, 0x07);ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_CONFIG, 0x06);/* 配置加速度传感器工作在 16G 模式, 不自检 */ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_ACCEL_CONFIG, 0x18);/* 陀螺仪自检及测量范围，典型值：0x18(不自检，2000deg/s) */ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_GYRO_CONFIG, 0x18);
#if MPU6050_USE_INT/* 配置中断产生时中断引脚为低电平 */ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_INT_PIN_CFG, &reg_val);reg_val |= 0xC0;mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_INT_PIN_CFG, reg_val);/* 开启数据就绪中断 */ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_INT_ENABLE, &reg_val);reg_val |= 0x01;mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_INT_ENABLE, reg_val);
#endifreturn ret;
}static int mpu6050_deinit(void)
{int ret = 0;/* mpu6050复位, 寄存器恢复默认值 */ret = mpu6050_i2c_write_reg(mpu6050_dev->client, MPU6050_PWR_MGMT_1, 0x80);return ret;
}static int mpu6050_read_id(uint8_t *id)
{uint8_t data;int ret = 0;ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_WHO_AM_I, &data);if (id != NULL)*id = data;if (data != MPU6050_IIC_ADDR)ret = -1;return ret;
}static int mpu6050_read_accel(struct mpu6050_accel *acc)
{int i = 0;int ret = 0;uint8_t data[6] = {0};for (i = 0; i < 6; i++){ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_ACCEL_XOUT_H+i, &data[i]);}acc->x = (data[0] << 8) + data[1];acc->y = (data[2] << 8) + data[3];acc->z = (data[4] << 8) + data[5];return ret;
}static int mpu6050_read_gyro(struct mpu6050_gyro *gyro)
{int i = 0;int ret = 0;uint8_t data[6] = {0};for (i = 0; i < 6; i++){ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_GYRO_XOUT_H+i, &data[i]);}gyro->x = (data[0] << 8) + data[1];gyro->y = (data[2] << 8) + data[3];gyro->z = (data[4] << 8) + data[5];return ret;
}static int mpu6050_read_temp(short *temp)
{int i = 0;int ret = 0;uint8_t data[2] = {0};for (i = 0; i < 2; i++){ret = mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_TEMP_OUT_H+i, &data[i]);}*temp = (data[0] << 8) + data[1];return ret;
}

2、linux I2C 驱动框架

在测试使用中断实现，发现中断触发太快和直接读取也没啥区别。

struct mpu6050_device
{int irq; /* 中断号 */int gpio;dev_t dev_no; /* 设备号 */struct cdev chrdev;struct class *class;struct mutex m_lock;wait_queue_head_t wq; /* 等待队列 */struct mpu6050_data data;struct i2c_client *client;
};static struct mpu6050_device *mpu6050_dev;static int _drv_open(struct inode *node, struct file *file)
{uint8_t id;int ret = 0;file->private_data = mpu6050_dev;ret = mpu6050_init();if (ret != 0){printk("%d-%s init failed %d\r\n", __LINE__, __FUNCTION__, ret);return -ENXIO;}if (mpu6050_read_id(&id) != 0){printk("don't find %s %d\r\n", DEV_NAME, id);return -ENXIO;}gpio_direction_input(mpu6050_dev->gpio);printk("%s open %d\r\n", DEV_NAME, __LINE__);return 0;
}static ssize_t _drv_read(struct file *filp, char __user *buf, size_t size, loff_t *offset)
{int ret;int data_size;struct mpu6050_device *tmp_mpu6050 = filp->private_data;struct mpu6050_data data;data_size = sizeof(data);if (size != data_size)return -EINVAL;
#if MPU6050_USE_INT == 0ret = mpu6050_read_accel(&data.accel);ret = mpu6050_read_gyro(&data.gyro);
#else#endifif (copy_to_user(buf, &data, sizeof(data))){ret = -EFAULT;}else{ret = data_size;}return ret;
}/* 使驱动支持多路复用IO */
static __poll_t _drv_poll(struct file *filp, struct poll_table_struct *wait)
{__poll_t mask = 0;// mutex_lock(&mpu6050_dev->m_lock);// poll_wait(filp, &mpu6050_dev->wq, wait);// mutex_unlock(&sr501.m_lock);return mask;
}static long _drv_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{int ret = 0;uint8_t result = 0;short buf[3];void __user *user_space = (void __user *)arg;switch (cmd){case MPU6050_CMD_GET_ID:ret = mpu6050_read_id(&result);ret = copy_to_user(user_space, &result, sizeof(result));break;case MPU6050_CMD_GET_ACCEL:ret = mpu6050_read_accel((struct mpu6050_accel *)&buf);ret = copy_to_user(user_space, &buf, sizeof(buf));break;case MPU6050_CMD_GET_GYRO:ret = mpu6050_read_gyro((struct mpu6050_gyro *)&buf);ret = copy_to_user(user_space, &buf, sizeof(buf));break;case MPU6050_CMD_GET_TEMP:ret = mpu6050_read_temp(&buf[0]);ret = copy_to_user(user_space, &buf[0], 2);break;}return ret;
}static int _drv_release(struct inode *node, struct file *filp)
{int ret = 0;struct mpu6050_device *tmp_mpu6050 = filp->private_data;ret = mpu6050_deinit();  return ret;
}static struct file_operations mpu6050_drv_ops = {.owner = THIS_MODULE,.open = _drv_open,.read = _drv_read,.poll = _drv_poll,.release = _drv_release,
};static irqreturn_t mpu6050_isr(int irq, void *dev)
{uint8_t reg_val;// printk("%s %d %s\n", __FILE__, __LINE__, __FUNCTION__);mpu6050_i2c_read_reg(mpu6050_dev->client, MPU6050_INT_STATUS, &reg_val);if (reg_val & 0x01)     {/* 唤醒进程去读取数据 */printk("data ready\n");}return IRQ_RETVAL(IRQ_HANDLED);
}

probe和remove函数实现：

static int _driver_probe(struct i2c_client *client, const struct i2c_device_id *id)
{int err = 0;// int ret = 0;struct device *_dev;struct device_node *_dts_node;mpu6050_dev = (struct mpu6050_device *)kzalloc(sizeof(struct mpu6050_device), GFP_KERNEL);if (!mpu6050_dev){printk("can't kzalloc mpu6050 dev\n");return -ENOMEM;}_dts_node = client->dev.of_node;if (!_dts_node){printk("mpu6050 dts node can not found!\r\n");err = -EINVAL;goto out_free_dev;}mpu6050_dev->client = client;printk("mpu6050 dtsirq %d !\r\n", client->irq);
#if 1// mpu6050_dev->gpio = of_get_named_gpio(_dts_node, AP3216C_READY_GPIO_NAME, 0);   /* 获取gpio */// if (!gpio_is_valid( mpu6050_dev->gpio)) {//     printk("don't get mpu6050 ready gpio!\n");//     err = -EINVAL;//     goto out_free_dev;// }// mpu6050_dev->irq = gpio_to_irq( mpu6050_dev->gpio);                              /* 通过gpio得到irq */// gpiod_direction_input(mpu6050_dev->gpio);          /* 设置gpio为输入 */mpu6050_dev->irq = client->irq;// mpu6050_dev->gpio = irq_to_gpio(mpu6050_dev->irq);err = request_irq(mpu6050_dev->irq, mpu6050_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, DEV_NAME, NULL); /* 申请中断 */if (err){printk(KERN_INFO "failed to request irq %d\r\n", mpu6050_dev->irq);goto out_free_dev;}/* 内核自动分配设备号 */err = alloc_chrdev_region(&mpu6050_dev->dev_no, 0, 1, DEV_NAME);if (err < 0){pr_err("Error: failed to register mbochs_dev, err: %d\n", err);goto out_free_irq;}cdev_init(&mpu6050_dev->chrdev, &mpu6050_drv_ops);err = cdev_add(&mpu6050_dev->chrdev, mpu6050_dev->dev_no, 1);if (err){goto out_unregister;}mpu6050_dev->class = class_create(THIS_MODULE, DEV_NAME);if (IS_ERR(mpu6050_dev->class)){err = PTR_ERR(mpu6050_dev->class);goto out_cdev_del;}/* 创建设备节点 */_dev = device_create(mpu6050_dev->class, NULL, mpu6050_dev->dev_no, NULL, DEV_NAME);if (IS_ERR(_dev)){ /* 判断指针是否合法 */err = PTR_ERR(_dev);goto out_class_del;}// mutex_init(&mpu6050_dev->m_lock);                 /* 初始化互斥锁  */printk("%s probe success\r\n", DEV_NAME);goto out;out_class_del:class_destroy(mpu6050_dev->class);
out_cdev_del:cdev_del(&mpu6050_dev->chrdev);
out_unregister:unregister_chrdev_region(mpu6050_dev->dev_no, 1); /* 注销设备 */
out_free_irq:free_irq(mpu6050_dev->irq, NULL);
out_free_dev:kfree(mpu6050_dev);mpu6050_dev = NULL;
out:
#endifreturn err;
}static int _driver_remove(struct i2c_client *client)
{device_destroy(mpu6050_dev->class, mpu6050_dev->dev_no);class_destroy(mpu6050_dev->class);cdev_del(&mpu6050_dev->chrdev);unregister_chrdev_region(mpu6050_dev->dev_no, 1); /* 注销设备 */free_irq(mpu6050_dev->irq, NULL); /* 释放中断*/kfree(mpu6050_dev);printk(KERN_INFO "%s success\n", DEV_NAME);return 0;
}

remove函数只要做一些清理工作，删除设备、删除class、注销设备以及释放内存等。

出口入口函数实现：

/* 设备树的匹配列表 */
static struct of_device_id dts_match_table[] = {{.compatible = MPU6050_DTS_COMPATIBLE}, /* 通过设备树来匹配 */{},
};/* 传统匹配方式 ID 列表 ，即使不使用也要添加，不然probe匹配不成功 */
static const struct i2c_device_id mpu6050_id[] = {{MPU6050_DTS_COMPATIBLE, 0},{},
};static struct i2c_driver mpu6050_driver = {.probe = _driver_probe,.remove = _driver_remove,.driver = {.name = MPU6050_DTS_COMPATIBLE,.owner = THIS_MODULE,.of_match_table = dts_match_table, /* 通过设备树匹配 */},.id_table = mpu6050_id,
};/* 入口函数 */
static int __init _driver_init(void)
{int ret = 0;ret = i2c_add_driver(&mpu6050_driver); /* 注册I2C驱动 */printk("%s %s\n", DEV_NAME, __FUNCTION__);return ret;
}/*  出口函数 */
static void __exit _driver_exit(void)
{printk("%s driver %s\n", DEV_NAME, __FUNCTION__);i2c_del_driver(&mpu6050_driver); /* 注销I2C驱动 */
}module_init(_driver_init);
module_exit(_driver_exit);MODULE_AUTHOR("Ares");
MODULE_LICENSE("GPL");

测试的app程序编写

#include "stdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <poll.h>
#include <stdint.h>#define DEV_NAME   "/dev/mpu6050"struct mpu6050_accel {short x;short y;short z;
};struct mpu6050_gyro {short x;short y;short z;
};struct mpu6050_data {struct mpu6050_accel accel;struct mpu6050_gyro gyro;
};void sleep_ms(unsigned int ms)
{struct timeval delay;delay.tv_sec = 0;delay.tv_usec = ms * 1000; select(0, NULL, NULL, NULL, &delay);
}int main(int argc, char **argv)
{int fd;int ret;/* 2. 打开文件 */fd = open(DEV_NAME, O_RDWR | O_NONBLOCK);   // | O_NONBLOCKif (fd < 0){printf("can not open file %s, %d\n", DEV_NAME, fd);return -1;}struct mpu6050_data   mpu6050_data;int size = sizeof(struct mpu6050_data);printf("read size %d\n", size);while (1){if (read(fd, &mpu6050_data, size) == size){printf("accel x %d y %d z %d\r\n", mpu6050_data.accel.x, mpu6050_data.accel.y, mpu6050_data.accel.z);printf("gyro x %d y %d z %d\r\n", mpu6050_data.gyro.x, mpu6050_data.gyro.y, mpu6050_data.gyro.z);}printf("running\r\n");sleep_ms(500);}close(fd);return 0;
}

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Linux驱动 | MPU6050驱动(I2C)