Using I2C to Drive PCA9555 Expansion Chip

tca9555@20{    compatible = "tca9555";    reg = <0x20>;};

#include <linux/module.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/fs.h>#include <linux/slab.h>#include <linux/uaccess.h>#include <linux/io.h>#include <linux/cdev.h>#include <linux/device.h>#include <linux/of.h>#include <linux/of_address.h>#include <linux/of_irq.h>#include <linux/gpio.h>#include <linux/of_gpio.h>#include <linux/string.h>#include <linux/irq.h>#include <linux/interrupt.h>#include <linux/input.h>#include <linux/i2c.h>#include <linux/delay.h>
#include "TCA9555.h"
static const struct of_device_id tca9555_of_match_table[] = {    {.compatible = "tca9555"},    {},};
/* Low-level read function */
int tca9555_read_reg(struct i2c_client *client, u8 reg_addr){    u8 data; // Value of the register, 8 bits
    /* Construct data */    struct i2c_msg msgs[] = {        /* The first segment of data is the device address (write address) */        {            .addr = client->addr,            .flags = 0,              // flags = 0 write = 1 read            .len = sizeof(reg_addr), // Length of data, here it is the length of the register address, 1 byte            .buf = &reg_addr,        // The data to be sent is the reg_addr passed in earlier        },        {            .addr = client->addr,            .flags = 1, // After sending the address, start reading the register value            .len = sizeof(data),            .buf = &data, // Length of data to read is 1 byte, storage location is data        }
    };
    /* Initiate I2C data transfer */    i2c_transfer(client->adapter, msgs, 2); // The number of msgs to send is 2
    return data;}
/* Low-level write function */
void tca9555_write_reg(struct i2c_client *client, u8 reg_addr, u8 data, u16 len){    u8 buffer[256]; // Value of the register, 8 bits
    /* Construct data */    struct i2c_msg msgs;
    buffer[0] = reg_addr;
    memcpy(&buffer[1], &data, len);
    msgs.addr = client->addr;    msgs.flags = 0; // flags = 0 write = 1 read    msgs.len = len + 1;    msgs.buf = buffer; // The data to be sent is the reg_addr passed in earlier
    /* Initiate I2C data transfer */    i2c_transfer(client->adapter, &msgs, 1); // The number of msgs to send is 1}
static int tca9555_probe(struct i2c_client *client, const struct i2c_device_id *id){    int i = 0;
    printk("tca9555_probe!\n");
    /* Configure registers: Configure pins as input or output, 0x06, 0x07 */    tca9555_write_reg(client, 0x06, 0x00, 1);    tca9555_write_reg(client, 0x07, 0x00, 1);
do    {
        /* Output registers: 0x02  0x03 */        tca9555_write_reg(client, 0x02, 0x00, 1);        tca9555_write_reg(client, 0x03, 0x00, 1);
        msleep(800);
        /* Output registers: 0x02  0x03 */        tca9555_write_reg(client, 0x02, 0xff, 1);        tca9555_write_reg(client, 0x03, 0xff, 1);
        msleep(200);
        i++;    } while (i < 65536);
    return 0;}
static int tca9555_remove(struct i2c_client *client){
    return 0;}
static struct i2c_driver tca9555_driver = {    .probe = tca9555_probe,    .remove = tca9555_remove,    .driver = {        .name = "tca9555",        .owner = THIS_MODULE,        .of_match_table = tca9555_of_match_table,    },};
static int __init tca9555_init(void){    int ret = 0;
    printk("tca9555_init\n");
    ret = i2c_add_driver(&tca9555_driver);
    if (ret < 0)        printk("i2c_add_driver is error\n");
    return 0;}
static void __exit tca9555_exit(void){    i2c_del_driver(&tca9555_driver);
    printk("tca9555_init\n");}
module_init(tca9555_init);module_exit(tca9555_exit);
MODULE_LICENSE("GPL");MODULE_AUTHOR("xx");