Exynos4412 IIC匯流排驅動開發(二)—— IIC 驅動開發
首先看一張程式碼層次圖,有助於我們的理解
上面這些程式碼的展示是告訴我們:linux核心和晶片提供商為我們的的驅動程式提供了 i2c驅動的框架,以及框架底層與硬體相關的程式碼的實現。
剩下的就是針對掛載在i2c兩線上的i2c裝置了device,而編寫的即具體裝置驅動了,這裡的裝置就是硬體介面外掛載的裝置,而非硬體介面本身(soc硬體介面本身的驅動可以理解為匯流排驅動)
一、編寫驅動需要完成的工作
編寫具體的I2C驅動時,工程師需要處理的主要工作如下:
1)、提供I2C介面卡的硬體驅動,探測,初始化I2C介面卡(如申請I2C的I/O地址和中斷號),驅動CPU控制的I2C介面卡從硬體上產生。
2)、提供I2C控制的algorithm, 用具體介面卡的xxx_xfer()函式填充i2c_algorithm的master_xfer指標,並把i2c_algorithm指標賦給i2c_adapter的algo指標。
3)、實現I2C裝置驅動中的i2c_driver介面,用具體yyy的yyy_probe(),yyy_remove(),yyy_suspend(),yyy_resume()函式指標和i2c_device_id裝置ID表賦給i2c_driver的probe,remove,suspend,resume和id_table指標。
4)、實現I2C裝置所對應型別的具體驅動,i2c_driver只是實現裝置與匯流排的掛接。
上面的工作中前兩個屬於I2C匯流排驅動,後面兩個屬於I2C裝置驅動。
二、開發例項
-------------------------------------------------------------------
開發板:Exynos4412-fs4412
Linux 核心版本:Linux 3.14
IIC 從機物件:陀螺儀MPU6050
--------------------------------------------------------------------
1、檢視原理圖
對應核心板pin
從機地址
可以獲取的資訊:
1、MPU6050 對應 IIC 通道5;
2、對應中斷 EINT27 父節點 GPX3 3
3、因為ad0接地,所以從裝置地址0x68
base address 0x138B0000
2、建立裝置樹節點
通過上面獲取的資訊,可以寫出
[email protected] {
#address-cells = <1>;
#size-cells = <0>;
samsung,i2c-sda-delay = <100>;
samsung,i2c-max-bus-freq = <20000>;
pinctrl-0 = <&i2c5_bus>;
pinctrl-names = "default";
status = "okay";
[email protected] {
compatible = "invense,mpu6050";
reg = <0x68>;
interrupt-parent = <&gpx3>;
interrupts = <3 2>;
};
};
3、MPU6050相應暫存器
#define SMPLRT_DIV 0x19 //取樣率分頻,典型值: 0x07(125Hz) */
#define CONFIG 0x1A // 低通濾波頻率,典型值: 0x06(5Hz) */
#define GYRO_CONFIG 0x1B // 陀螺儀自檢及測量範圍,典型值: 0x18(不自檢,2000deg/s) */
#define ACCEL_CONFIG 0x1C // 加速計自檢、測量範圍及高通濾波頻率,典型值: 0x01(不自檢, 2G, 5Hz) */
#define ACCEL_XOUT_H 0x3B // 儲存最近的 X 軸、 Y 軸、 Z 軸加速度感應器的測量值 */
#define ACCEL_XOUT_L 0x3C
#define ACCEL_YOUT_H 0x3D
#define ACCEL_YOUT_L 0x3E
#define ACCEL_ZOUT_H 0x3F
#define ACCEL_ZOUT_L 0x40
#define TEMP_OUT_H 0x41 // 儲存的最近溫度感測器的測量值 */
#define TEMP_OUT_L 0x42
#define GYRO_XOUT_H 0x43 // 儲存最近的 X 軸、 Y 軸、 Z 軸陀螺儀感應器的測量值 */
#define GYRO_XOUT_L 0x44
#define GYRO_YOUT_H 0x45
#define GYRO_YOUT_L 0x46
#define GYRO_ZOUT_H 0x47
#define GYRO_ZOUT_L 0x48
#define PWR_MGMT_1 0x6B // 電源管理,典型值: 0x00(正常啟用) */
#define WHO_AM_I 0x75 //IIC 地址暫存器(預設數值 0x68,只讀) */
4、具體程式
mpu6050.h
#ifndef MPU6050_HHHH
#define MPU6050_HHHH
#define MPU6050_MAGIC 'K'
union mpu6050_data
{
struct {
unsigned short x;
unsigned short y;
unsigned short z;
}accel;
struct {
unsigned short x;
unsigned short y;
unsigned short z;
}gyro;
unsigned short temp;
};
#define GET_ACCEL _IOR(MPU6050_MAGIC, 0, union mpu6050_data)
#define GET_GYRO _IOR(MPU6050_MAGIC, 1, union mpu6050_data)
#define GET_TEMP _IOR(MPU6050_MAGIC, 2, union mpu6050_data)
#endif
i2c_driver
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include "mpu6050.h"
MODULE_LICENSE("GPL");
#define SMPLRT_DIV 0x19
#define CONFIG 0x1A
#define GYRO_CONFIG 0x1B
#define ACCEL_CONFIG 0x1C
#define ACCEL_XOUT_H 0x3B
#define ACCEL_XOUT_L 0x3C
#define ACCEL_YOUT_H 0x3D
#define ACCEL_YOUT_L 0x3E
#define ACCEL_ZOUT_H 0x3F
#define ACCEL_ZOUT_L 0x40
#define TEMP_OUT_H 0x41
#define TEMP_OUT_L 0x42
#define GYRO_XOUT_H 0x43
#define GYRO_XOUT_L 0x44
#define GYRO_YOUT_H 0x45
#define GYRO_YOUT_L 0x46
#define GYRO_ZOUT_H 0x47
#define GYRO_ZOUT_L 0x48
#define PWR_MGMT_1 0x6B
#define MPU6050_MAJOR 500
#define MPU6050_MINOR 0
struct mpu6050_device {
struct cdev cdev;
struct i2c_client *client;
};
struct mpu6050_device *mpu6050;
static int mpu6050_read_byte(struct i2c_client *client, unsigned char reg)
{
int ret;
char txbuf[1] = { reg };
char rxbuf[1];
struct i2c_msg msg[2] = {
{client->addr, 0, 1, txbuf},
{client->addr, I2C_M_RD, 1, rxbuf}
};
ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
if (ret < 0) {
printk("ret = %d\n", ret);
return ret;
}
return rxbuf[0];
}
static int mpu6050_write_byte(struct i2c_client *client, unsigned char reg, unsigned char val)
{
char txbuf[2] = {reg, val};
struct i2c_msg msg[2] = {
{client->addr, 0, 2, txbuf},
};
i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
return 0;
}
static int mpu6050_open(struct inode *inode, struct file *file)
{
return 0;
}
static int mpu6050_release(struct inode *inode, struct file *file)
{
return 0;
}
static long mpu6050_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
union mpu6050_data data;
struct i2c_client *client = mpu6050->client;
switch(cmd) {
case GET_ACCEL:
data.accel.x = mpu6050_read_byte(client, ACCEL_XOUT_L);
data.accel.x |= mpu6050_read_byte(client, ACCEL_XOUT_H) << 8;
data.accel.y = mpu6050_read_byte(client, ACCEL_YOUT_L);
data.accel.y |= mpu6050_read_byte(client, ACCEL_YOUT_H) << 8;
data.accel.z = mpu6050_read_byte(client, ACCEL_ZOUT_L);
data.accel.z |= mpu6050_read_byte(client, ACCEL_ZOUT_H) << 8;
break;
case GET_GYRO:
data.gyro.x = mpu6050_read_byte(client, GYRO_XOUT_L);
data.gyro.x |= mpu6050_read_byte(client, GYRO_XOUT_H) << 8;
data.gyro.y = mpu6050_read_byte(client, GYRO_YOUT_L);
data.gyro.y |= mpu6050_read_byte(client, GYRO_YOUT_H) << 8;
data.gyro.z = mpu6050_read_byte(client, GYRO_ZOUT_L);
data.gyro.z |= mpu6050_read_byte(client, GYRO_ZOUT_H) << 8;
break;
case GET_TEMP:
data.temp = mpu6050_read_byte(client, TEMP_OUT_L);
data.temp |= mpu6050_read_byte(client, TEMP_OUT_H) << 8;
break;
default:
printk("invalid argument\n");
return -EINVAL;
}
if (copy_to_user((void *)arg, &data, sizeof(data)))
return -EFAULT;
return sizeof(data);
}
struct file_operations mpu6050_fops = {
.owner = THIS_MODULE,
.open = mpu6050_open,
.release = mpu6050_release,
.unlocked_ioctl = mpu6050_ioctl,
};
static int mpu6050_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
int ret;
dev_t devno = MKDEV(MPU6050_MAJOR, MPU6050_MINOR);
printk("match OK!\n");
mpu6050 = kzalloc(sizeof(*mpu6050), GFP_KERNEL);
if (mpu6050 == NULL) {
return -ENOMEM;
}
mpu6050->client = client;
ret = register_chrdev_region(devno, 1, "mpu6050");
if (ret < 0) {
printk("failed to register char device region!\n");
goto err1;
}
cdev_init(&mpu6050->cdev, &mpu6050_fops);
mpu6050->cdev.owner = THIS_MODULE;
ret = cdev_add(&mpu6050->cdev, devno, 1);
if (ret < 0) {
printk("failed to add device\n");
goto err2;
}
mpu6050_write_byte(client, PWR_MGMT_1, 0x00);
mpu6050_write_byte(client, SMPLRT_DIV, 0x07);
mpu6050_write_byte(client, CONFIG, 0x06);
mpu6050_write_byte(client, GYRO_CONFIG, 0xF8);
mpu6050_write_byte(client, ACCEL_CONFIG, 0x19);
return 0;
err2:
unregister_chrdev_region(devno, 1);
err1:
kfree(mpu6050);
return ret;
}
static int mpu6050_remove(struct i2c_client *client)
{
dev_t devno = MKDEV(MPU6050_MAJOR, MPU6050_MINOR);
cdev_del(&mpu6050->cdev);
unregister_chrdev_region(devno, 1);
kfree(mpu6050);
return 0;
}
static const struct i2c_device_id mpu6050_id[] = {
{ "mpu6050", 0},
{}
};
static struct of_device_id mpu6050_dt_match[] = {
{.compatible = "invense,mpu6050" },
{/*northing to be done*/},
};
struct i2c_driver mpu6050_driver = {
.driver = {
.name = "mpu6050",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(mpu6050_dt_match),
},
.probe = mpu6050_probe,
.remove = mpu6050_remove,
.id_table = mpu6050_id,
};
static init _init mpu6050_init(void)
{
return i2c_add_driver(&mpu6050_driver);
}
static void _exit mpu6050_exit(void)
{
return i2c_del_driver(&mpu6050_driver);
}
module_init(&mpu6050_init);
module_exit(&mpu6050_exit);
test.c#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include "mpu6050.h"
int main(int argc, const char *argv[])
{
int fd;
union mpu6050_data data;
fd = open("/dev/mpu6050", O_RDWR);
if (fd < 0) {
perror("open");
exit(1);
}
while(1) {
ioctl(fd, GET_ACCEL, &data);
printf("acceleration data: x = %04x, y = %04x, z = %04x\n",
data.accel.x, data.accel.y, data.accel.z);
ioctl(fd, GET_GYRO, &data);
printf("gyroscope data: x = %04x, y = %04x, z = %04x\n",
data.accel.x, data.accel.y, data.accel.z);
sleep(1);
}
close(fd);
return 0;
}