Linux 驱动——IIC（AT24C02）
at24c02_drv.c文件:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#define DEVICE_NAME "at24c02"
#define DRIVER_NAME "at24c02_drv"
static i2c_client *at24c02_client;
int major;
struct class *at24c02dev_class;
struct class_device *at24c02dev_class_device;
static unsigned short ignore[] = {I2C_CLIENT_END};
static unsigned short normal_addr[] = {0x50, I2C_CLIENT_END};
static ssize_t at24c02_drv_read(struct file *file, char __user *userbuf, size_t count, loff_t *off)
{
struct i2c_msg msg[2];
u8 addr, data;
int ret;
cpoy_from_user(&addr, userbuf, 1);
msg[0].addr = at24c02_client->addr;
msg[0].flags = 0; //写标志
msg[0].len = 1;
msg[0].buf = &addr //写入要读的地址
msg[1].addr = at24c02_client->addr;
msg[1].flags = I2C_M_RD; //读标志
msg[1].len = 1;
msg[1].buf = &data //读出数据
ret = i2c_transfer(at24c02_client->adapter, msg, 2);
if(ret == 2) //表示2个msg传输成功
{
copy_to_user(buf, &data, 1); //上传数据
return 0;
}
else
return -EAGAIN;
}
static ssize_t at24c02_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
struct i2c_msg msg[1];
u8 addr_and_data[2];
int ret;
copy_from_user(addr_and_data, buf, 2); //获取 地址 数据
msg[0].addr = at24c02_client->addr;
msg[0].flags = 0; //写标志
msg[0].len = 2;
msg[0].buf = addr_and_data; //写入要写的地址和数据
ret = i2c_transfer(at24c02_client->adapter, msg, 1);
if(ret == 1) //表示1个msg传输成功
return 0;
else
return -EAGAIN;
}
struct file_operations at24c02_drv_fops = {
.owner = THIS_MODULE,
.read = at24c02_drv_read,
.write = at24c02_drv_write,
};
struct i2c_client_address_data at24c02_addr = {
.normal_i2c = normal_addr; //存放正常的设备高7位地址数据
.probe = ignore; //存放不受*ignore影响的高7位设备地址数据
.ignore = ignore; //存放*ignore的高7位设备地址数据
};
static i2c_driver at24c02_driver = {
.driver = {
.name = "at24c02",
},
.id = I2C_DRIVERID_EEPROM,
.attach_adapter = at24c02_attach_adapter,
.detach_client = at24c02_detach_client,
};
static int at24c02_detach_client(struct i2c_client *client)
{
i2c_detach_client(at24c02_client);
kfree(at24c02_client);
class_device_destory(at24c02dev_class, MKDEV(major, 0));
class_destory(at24c02dev_class);
return 0;
}
//注册真正地IIC设备
static int at24c02_detect(struct i2c_adapter *adap, int addr, int kind)
{
//分配并初始化i2c_client结构体
at24c02_client = kzalloc(sizeof(i2c_adapter *adap), GFP_KERNEL);
at24c02_client->addr = addr;
at24c02_client->adapter = adap;
at24c02_client->driver = &at24c02_driver
at24c02_client->flags = 0;
strlcpy(at24c02_client->name, DEVICE_NAME, I2C_NAME_SIZE); //设置IIC设备的名字
//将at24c02_client与适配器进行连接
i2c_attach_client(at24c02_client);
//注册字符类设备
major = regeister_chrdev(0, DEVICE_NAME, &at24c02_drv_fops); //注册字符设备
at24c02dev_class = class_create(THID_MODULE, DEVICE_NAME); //注册设备类
at24c02dev_class_device = class_device_create(at24c02dev_class, NULL, MKEDV(major, 0), NULL, DEVICE_NAME);
}
//发送IIC设备的地址at24c02_addr, 如果有响应则调用回调函数at24c02_detect
static int at24c02_attach_adapter(struct i2c_adapter *adapter)
{
return i2c_probe(adapter, &at24c02_addr, at24c02_detect);
}
static int at24c02_drv_init()
{
i2c_add_driver(&at24c02_driver);
return 0;
}
static void at24c02_drv_exit()
{
i2c_del_driver(&at24c02_driver);
}
module_init(at24c02_drv_init);
module_exit(at24c02_drv_exit);
MODULE_LICENSE("GPL");
Makefile文件：
obj-m += at24c02_drv.o
KERN_DIR = /work/system/linux-2.6.22.6
all:
make -C $(KERN_DIR) M=`pwd` modules
clean:
rm -rf *.o *.ko *.order *.symvers *.mod.c
at24c02_app.c文件：
#include "sys/types.h"
#include "sys/stst.h"
#include "stdio.h"
#include "fcntl.h"
void print_usage(char *file)
{
printf("%s r addr \n", file);
printf("%s w addr val \n", file);
}
int main(int argc, char **argv)
{
int fd;
char *filename = argv[1];
fd = open(filename, O_RDWR); //以阻塞的方式打开设备文件
if(fd < 0)
{
printf("error, can not open %s \n", filename);
return -1;
}
if(strcmp(argv[2], "r") == 0)
{
buf[0] = strtoul(argv[3], NULL, 0);
read(fd, buf, 1);
printf("data: %c, %d, 0x2x \n", buf[0], buf[0], buf[0]);
}
else if(strcmp(argv[2], "w") == 0)
{
buf[0] = strtoul(argv[3], NULL, 0);
buf[1] = strtoul(argv[4], NULL, 0);
write(fd, buf, 2);
}
else
{
print_usage(argv[0]);
return -1;
}
}
编译生成at24c02_drv.ko和at24c02_app, 运行./at24c02_app /dev/at24c02 r xxxx
./at24c02_app /dev/at24c02 w xxxx xxxx
