在RK3399下IIC驱动的方式分别有哪几种呢

方式一

前面说了iic在新内核下的一种方式，下面是第二种方式,这种方式在fireflyWiki教程里面有说明

代码如下

#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 *iic_client;

static int read_reg(const struct i2c_client *client, unsigned int *buf , unsigned char address)
{
struct i2c_msg msg[2];
int ret;
unsigned char date1[2];

msg[0].addr  = client->addr;  
msg[0].buf   = &address;              
msg[0].len   = 1;                     
msg[0].flags = 0;                   

msg[1].addr  = client->addr; 
msg[1].buf   = date1;                 
msg[1].len   = 2;                    
msg[1].flags = I2C_M_RD;                   

ret = i2c_transfer(client->adapter, msg, 2);
if (ret > 0)
{
	printk(KERN_INFO "date1 : %d date1 :%d\n",date1[0],date1[1]);
	*buf = (date1[0] << 8) | (date1[1]); 
	return 1;
}
else
	return -EIO;

}

static struct file_operations iic_fops = {
.owner = THIS_MODULE,

};

static int iic_probe(struct i2c_client *client,const struct i2c_device_id *id)
{
int ret;
unsigned int data = 0;
iic_client = client;

printk(KERN_INFO "%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
major = register_chrdev(0, "iic", &iic_fops);
class = class_create(THIS_MODULE, "iic");
device_create(class, NULL, MKDEV(major, 0), NULL, "iic"); 
ret = read_reg(iic_client,&data,0xff);
printk(KERN_INFO "Device ID 0x%x\n",data);
return 0;

}

static int iic_remove(struct i2c_client *client)
{
printk(KERN_INFO "%s %s %d\n", FILE, FUNCTION, LINE);
device_destroy(class, MKDEV(major, 0));
class_destroy(class);
unregister_chrdev(major, "iic");

return 0;

}

static const struct i2c_device_id iic_id_table[] = {
{ "iic_test", 0 },
{}
};
static const struct of_device_id of_alc_match[] = {
{ .compatible = "alc5651" },
{ }
};

static struct i2c_driver iic_driver = {
.driver = {
.name = "rt5651_iic",
.owner = THIS_MODULE,
.of_match_table = of_alc_match,
},
.probe = iic_probe,
.remove = iic_remove,
.id_table = iic_id_table,
};

static int iic_drv_init(void)
{
printk(KERN_INFO "%s %s %d\n", FILE, FUNCTION, LINE);
i2c_add_driver(&iic_driver);

return 0;

}

static void iic_drv_exit(void)
{
i2c_del_driver(&iic_driver);
}

module_init(iic_drv_init);
module_exit(iic_drv_exit);
MODULE_LICENSE("GPL");

makefile文件就不贴了，前一篇文章有说

dts文件中新增内容：

&i2c1 {
status = "okay";
i2c-scl-rising-time-ns = <300>;
i2c-scl-falling-time-ns = <15>;

rt5651: rt5651@1a {
            #sound-dai-cells = <0>;
            compatible = "realtek,rt5651";
            reg = <0x1a>;
            clocks = <&cru SCLK_I2S_8CH_OUT>;
            clock-names = "mclk";
            pinctrl-names = "default";
            pinctrl-0 = <&i2s_8ch_mclk>;
            spk-con-gpio = <&gpio0 11 GPIO_ACTIVE_HIGH>;
    };

    alc5651: alc5651@1a{ //新增的内容
            status = "okay";
            compatible = "alc5651";
            reg = <0x1a>;//iic设备地址，不可忽略，必须写对
    };

};

一样，还是贴一下结果，注意，这里的模块里面没有iic_dev.ko，只有iic_dts.ko这个模块被加载

g3399:/storage/0000-0000 # ls
LOST.DIR cmd_test iic_dev.ko test.ko
System Volume Information iic.ko iic_dts.ko test_char.ko
g3399:/storage/0000-0000 # insmod iic_dts.ko
[ 449.444537] /rk3399/source/g3399-v7-1-2-20180529/test_code/iic/iic_dts.c iic_drv_init 96
[ 449.452793] /rk3399/source/g3399-v7-1-2-20180529/test_code/iic/iic_dts.c iic_probe 55
[ 449.456078] dag3399:/storage/0000-0000 # te1 : 98 date1 :129
[ 449.456099] Device ID 0x6281

g3399:/storage/0000-0000 #
g3399:/storage/0000-0000 #
g3399:/storage/0000-0000 #
g3399:/storage/0000-0000 # lsmod
Module Size Used by
iic_dts 4050 0
g3399:/storage/0000-0000 #

原作者：mfence