3.4.2内核下I2C驱动之24CXX实例

#include "linux/kernel.h"

#include "linux/module.h"

#include "linux/platform_device.h"

#include "linux/i2c.h"

#include "linux/err.h"

#include "linux/regmap.h"

#include "linux/slab.h"

static struct i2c_board_info at24cxx_info = {

I2C_BOARD_INFO("at24c08", 0x50),

};

static struct i2c_client *at24cxx_client;

static int at24cxx_dev_init(void)

{

struct i2c_adapter *i2c_adap;

i2c_adap = i2c_get_adapter(0);

at24cxx_client = i2c_new_device(i2c_adap, &at24cxx_info);

i2c_put_adapter(i2c_adap);

return 0;

}

static void at24cxx_dev_exit(void)

{

i2c_unregister_device(at24cxx_client);

}

module_init(at24cxx_dev_init);

module_exit(at24cxx_dev_exit);

MODULE_LICENSE("GPL");

=================================================================

at24cxx_drv.c部分：

#include "linux/kernel.h"

#include "linux/module.h"

#include "linux/platform_device.h"

#include "linux/i2c.h"

#include "linux/err.h"

#include "linux/regmap.h"

#include "linux/slab.h"

#include "linux/fs.h"

#include "asm/uaccess.h"

static int major;

static struct class *class;

static struct i2c_client *at24cxx_client;

// 传入: buf[0] : addr

// 输出: buf[0] : data

//

static ssize_t at24cxx_read(struct file * file, char __user *buf, size_t count, loff_t *off)

{

unsigned char addr, data;

copy_from_user(&addr, buf, 1);

data = i2c_smbus_read_byte_data(at24cxx_client, addr);

copy_to_user(buf, &data, 1);

return 1;

}

// buf[0] : addr

// buf[1] : data

//

static ssize_t at24cxx_write(struct file *file, const char __user *buf, size_t count, loff_t *off)

{

unsigned char ker_buf[2];

unsigned char addr, data;

copy_from_user(ker_buf, buf, 2);

addr = ker_buf[0];

data = ker_buf[1];

printk("addr = 0xx, data = 0xx\n", addr, data);

if (!i2c_smbus_write_byte_data(at24cxx_client, addr, data))

return 2;

else

return -EIO;

}

static struct file_operations at24cxx_fops = {

.owner = THIS_MODULE,

.read = at24cxx_read,

.write = at24cxx_write,

};

static int __devinit at24cxx_probe(struct i2c_client *client,

const struct i2c_device_id *id)

{

at24cxx_client = client;

//printk("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);

major = register_chrdev(0, "at24cxx", &at24cxx_fops);

class = class_create(THIS_MODULE, "at24cxx");

device_create(class, NULL, MKDEV(major, 0), NULL, "at24cxx"); // /dev/at24cxx //

return 0;

}

static int __devexit at24cxx_remove(struct i2c_client *client)

{

//printk("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);

device_destroy(class, MKDEV(major, 0));

class_destroy(class);

unregister_chrdev(major, "at24cxx");

return 0;

}

static const struct i2c_device_id at24cxx_id_table[] = {

{ "at24c08", 0 },

{}

};

// 1. 分配/设置i2c_driver //

static struct i2c_driver at24cxx_driver = {

.driver = {

.name = "100ask",

.owner = THIS_MODULE,

},

.probe = at24cxx_probe,

.remove = __devexit_p(at24cxx_remove),

.id_table = at24cxx_id_table,

};

static int at24cxx_drv_init(void)

{

// 2. 注册i2c_driver //

i2c_add_driver(&at24cxx_driver);

return 0;

}

static void at24cxx_drv_exit(void)

{

i2c_del_driver(&at24cxx_driver);

}

module_init(at24cxx_drv_init);

module_exit(at24cxx_drv_exit);

MODULE_LICENSE("GPL");

=================================================================

i2c_test.c测试程序：

#include "stdio.h"

#include "stdlib.h"

#include "string.h"

#include "sys/types.h"

#include "sys/stat.h"

#include "fcntl.h"

// i2c_test r addr

// i2c_test w addr val

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;

unsigned char buf[2];

if ((argc != 3) && (argc != 4))

{

print_usage(argv[0]);

return -1;

}

fd = open("/dev/at24cxx", O_RDWR);