2018年10月12日 | Tiny210 IIC驱动之at24cxx访问

at24cxx_dev.c驱动源码：

#include "linux/kernel.h"

#include "linux/module.h"

#include "linux/platform_device.h"

#include "linux/i2c.h"

#include "linux/err.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驱动源码：

#include "linux/kernel.h"

#include "linux/module.h"

#include "linux/platform_device.h"

#include "linux/i2c.h"

#include "linux/err.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);

    if (fd < 0)

    {

        printf("can't open /dev/at24cxx\n");

        return -1;

    }

    if (strcmp(argv[1], "r") == 0)

    {

        buf[0] = strtoul(argv[2], NULL, 0);

        read(fd, buf, 1);

        printf("data: %c, %d, 0x%2x\n", buf[0], buf[0], buf[0]);

    }

    else if ((strcmp(argv[1], "w") == 0) && (argc == 4))

    {

        buf[0] = strtoul(argv[2], NULL, 0);

        buf[1] = strtoul(argv[3], NULL, 0);

        if (write(fd, buf, 2) != 2)

            printf("write err, addr = 0xx, data = 0xx\n", buf[0], buf[1]);

    }

    else

    {

        print_usage(argv[0]);

        return -1;

    }

    return 0;

}