嵌入式Linux驅動筆記(十一)------i2c裝置之mpu6050驅動
阿新 • • 發佈：2019-02-07
你好！這裡是風箏的部落格，
歡迎和我一起交流。
上一節講了i2c框架： 嵌入式Linux驅動筆記(十)——通俗易懂式瞭解i2c框架
這次就來寫一寫真正的i2c裝置驅動：
mpu6050是一款6軸運動處理元件，採用i2c通訊介面。
首先是廠家提供的mpu6050.h檔案：
#ifndef __MPU6050_H_
#define __MPU6050_H_
//定義MPU6050硬體地址
#define MPU_ADDR 0X68//接地為0X68 接高電平為0X69
//定義MPU6050暫存器地址
//#define MPU_ACCEL_OFFS_REG 0X06 //accel_offs暫存器,可讀取版本號,暫存器手冊未提到 再看下device部分檔案，可惜裝置樹還沒弄好，麻煩啊……
mpu_dev.c檔案：
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
static struct i2c_board_info mpu6050_info = {
I2C_BOARD_INFO("mpu6050", 0X68),//接地為0X68 接高電平為0X69
};
static struct i2c_client *mpu6050_client;
static int I2C_mpu6050_init(void)
{
struct i2c_adapter *i2c_adap;
i2c_adap = i2c_get_adapter(0);
mpu6050_client = i2c_new_device(i2c_adap, &mpu6050_info);
i2c_put_adapter(i2c_adap);
return 0;
}
static void I2C_mpu6050_exit(void)
{
i2c_unregister_device(mpu6050_client);
}
module_init(I2C_mpu6050_init);
module_exit(I2C_mpu6050_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("kite");/*modinfo my_keyboard.ko*/
MODULE_DESCRIPTION("A mpu6050 Module for testing module ");
MODULE_VERSION("V1.0");
因為是接在i2c0上，所以是獲取adapter0，同時寫上i2c器件的地址0x68。
再接著當然是driver部分了：
mpu_drv.c檔案:
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <asm/mach/map.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include "mpu6050.h"
/* 1. 確定主裝置號 */
static int major;
static struct cdev mpu6050_cdev;
static struct class *cls;
static struct i2c_client * mpu6050_client;
static int mpu6050_read_len(struct i2c_client * client, unsigned char reg_add , unsigned char len, unsigned char *buf)
{
int ret;
/* 要讀取的那個暫存器的地址 */
char txbuf = reg_add;
struct i2c_msg msg[] = {
{client->addr, 0, 1, &txbuf}, //0表示寫，
{client->addr, I2C_M_RD, len, buf}, //讀資料
};
/* 通過i2c_transfer函式操作msg */
ret = i2c_transfer(client->adapter, msg, 2); //執行2條msg
if (ret < 0)
{
printk("i2c_transfer read err\n");
return -1;
}
return 0;
}
static int mpu6050_read_byte(struct i2c_client * client, unsigned char reg_add)
{
int ret;
/* 要讀取的那個暫存器的地址 */
char txbuf = reg_add;
/* 用來接收讀到的資料 */
char rxbuf[1];
/* i2c_msg指明要操作的從機地址，方向，長度，緩衝區 */
struct i2c_msg msg[] = {
{client->addr, 0, 1, &txbuf}, //0表示寫，
{client->addr, I2C_M_RD, 1, rxbuf}, //讀資料
};
/* 通過i2c_transfer函式操作msg */
ret = i2c_transfer(client->adapter, msg, 2); //執行2條msg
if (ret < 0)
{
printk("i2c_transfer read err\n");
return -1;
}
return rxbuf[0];
}
static int mpu6050_write_byte(struct i2c_client * client, unsigned char reg_addr, unsigned char data)
{
int ret;
/* 要寫的那個暫存器的地址和要寫的資料 */
char txbuf[] = {reg_addr, data};
struct i2c_msg msg[] = {
{client->addr, 0, 2, txbuf}//0表示寫
};
ret = i2c_transfer(client->adapter, msg, 1);
if (ret < 0)
{
printk("i2c_transfer write err\n");
return -1;
}
return 0;
}
static int mpu6050_open(struct inode *inode, struct file *file)
{
char res;
printk("%s called\n", __func__);
mpu6050_write_byte(mpu6050_client, MPU_PWR_MGMT1_REG, 0X80);/*復位MPU6050*/
mdelay(100);
mpu6050_write_byte(mpu6050_client, MPU_PWR_MGMT1_REG, 0X00);
mpu6050_write_byte(mpu6050_client, MPU_GYRO_CFG_REG, 3<<3);/*陀螺儀感測器,±2000dps*/
mpu6050_write_byte(mpu6050_client, MPU_ACCEL_CFG_REG, 0<<3);/*加速度感測器,±2g*/
mpu6050_write_byte(mpu6050_client, MPU_SAMPLE_RATE_REG, 1000 /50-1);/*設定取樣率50Hz*/
mpu6050_write_byte(mpu6050_client, MPU_CFG_REG, 4);/*自動設定LPF為取樣率的一半*/
mpu6050_write_byte(mpu6050_client, MPU_INT_EN_REG, 0X00);/*關閉所有中斷*/
mpu6050_write_byte(mpu6050_client, MPU_USER_CTRL_REG, 0X00);/*I2C主模式關閉*/
mpu6050_write_byte(mpu6050_client, MPU_FIFO_EN_REG, 0X00);/*關閉FIFO*/
mpu6050_write_byte(mpu6050_client, MPU_INTBP_CFG_REG, 0X80);/*INT引腳低電平有效*/
res = mpu6050_read_byte(mpu6050_client, MPU_DEVICE_ID_REG);
mpu6050_write_byte(mpu6050_client, MPU_CFG_REG, 3);//設定數字低通濾波器
if (res == MPU_ADDR)//器件ID正確
{
printk("I2C ID is right ! \n");
mpu6050_write_byte(mpu6050_client, MPU_PWR_MGMT1_REG, 0X01); /*設定CLKSEL,PLL X軸為參考*/
mpu6050_write_byte(mpu6050_client, MPU_PWR_MGMT2_REG, 0X00); /*加速度與陀螺儀都工作*/
return 0;
}
printk("failed !I2C ID is error ! \n");
return 0;
}
static ssize_t mpu6050_read(struct file * file, char __user *buf, size_t count, loff_t *off)
{
char val;
unsigned char rxbuf[6], res;
copy_from_user(&val, buf, 1);
res = mpu6050_read_len(mpu6050_client, MPU_ACCEL_XOUTH_REG, 6 , rxbuf);
if (res == 0)/* 加速度計原始資料 */
{
printk("ax = %d \n", ((u16)rxbuf[0] << 8) | rxbuf[1]);
printk("ay = %d \n", ((u16)rxbuf[2] << 8) | rxbuf[3]);
printk("az = %d \n", ((u16)rxbuf[4] << 8) | rxbuf[5]);
}
res = mpu6050_read_len(mpu6050_client, MPU_GYRO_XOUTH_REG, 6 , rxbuf);
if (res == 0)/*陀螺儀原始資料*/
{
printk("gx = %d \n", ((u16)rxbuf[0] << 8) | rxbuf[1]);
printk("gy = %d \n", ((u16)rxbuf[2] << 8) | rxbuf[3]);
printk("gz = %d \n", ((u16)rxbuf[4] << 8) | rxbuf[5]);
}
return 0;
}
static ssize_t mpu6050_write(struct file *file, const char __user *buf, size_t count , loff_t * ppos)
{
return 0;
}
static long mpu6050_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
return 0;
}
/* 2. 構造file_operations */
static struct file_operations mpu6050_fops = {
.owner = THIS_MODULE,
.open = mpu6050_open,
.read = mpu6050_read,
.write = mpu6050_write,
.unlocked_ioctl = mpu6050_ioctl,
};
static int mpu6050_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
int res;
struct device *mpu6050_res;
dev_t devid;
mpu6050_client = client;
/* 3. 告訴核心 */
#if 0
major = register_chrdev(0, "hello", &hello_fops); /* (major, 0), (major, 1), ..., (major, 255)都對應hello_fops */
#else /*僅僅是註冊裝置號*/
if (major) {
devid = MKDEV(major, 0);
register_chrdev_region(devid, 1, "mpu6050"); /* (major,0) 對應 pwm_fops, (major, 1~255)都不對應pwm_fops */
} else {
alloc_chrdev_region(&devid, 0, 1, "mpu6050"); /* (major,0) 對應 pwm_fops, (major, 1~255)都不對應pwm_fops */
major = MAJOR(devid);
}
cdev_init(&mpu6050_cdev, &mpu6050_fops);
res=cdev_add(&mpu6050_cdev, devid, 1);
if(res)
{
printk("cdev_add failed\n");
unregister_chrdev_region(MKDEV(major, 0), 1);
return 0;
}
#endif
cls = class_create(THIS_MODULE, "mpu6050");
mpu6050_res = device_create(cls, NULL, MKDEV(major, 0), NULL, "mpu6050"); /* /dev/xxx */
if (IS_ERR(mpu6050_res))
{
printk("device_create failed\n");
return 0;
}
return 0;
}
static int mpu6050_remove(struct i2c_client *client)
{
device_destroy(cls, MKDEV(major, 0));//class_device_destroy(cls,MKDEV(major, 0));
class_destroy(cls);
cdev_del(&mpu6050_cdev);
unregister_chrdev_region(MKDEV(major, 0), 1);
return 0;
}
static const struct i2c_device_id mpu6050_id[] = {
{ "mpu6050", 0},
{}
};
struct i2c_driver mpu6050_driver = {
.driver = {
.name = "mpu6050",
.owner = THIS_MODULE,
},
.probe = mpu6050_probe,
.remove = mpu6050_remove,
.id_table = mpu6050_id,
};
static int I2C_mpu6050_init(void)
{
return i2c_add_driver(&mpu6050_driver);
}
static void I2C_mpu6050_exit(void)
{
return i2c_del_driver(&mpu6050_driver);
}
module_init(I2C_mpu6050_init);
module_exit(I2C_mpu6050_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("kite");/*modinfo my_keyboard.ko*/
MODULE_DESCRIPTION("A i2c-mpu6050 Module for testing module ");
MODULE_VERSION("V1.0");
如果理解了之前講的i2c框架，這部分就很好理解咯。
i2c裝置的讀寫函式都是用到了i2c_transfer函式。
最後就是應用程式咯：
mpu6050_test.c：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(int argc, char **argv)
{
int fd;
char val;
fd = open("/dev/mpu6050", O_RDWR);
if (fd < 0)
printf("can't open /dev/pwm\n");
else
printf("can open /dev/pwm\n");
read(fd, &val, 1);
return 0;
}
很簡單的i2c引用，再此小試牛刀了。
後記，編寫i2c驅動時，可以善用i2ctools，具體的可以去網上了解下：
cd /sys/bus/i2c/devices/
i2cdetect -y 0
這樣可以看到掛在i2c匯流排0下的所以i2c器件地址。
i2cdump -f -y 0 0x68
可以看到i2c匯流排0下的0x68地址的器件的暫存器內容