Linux 驱动程序开发（使用 I2C 总线设备驱动程序模型编写 AT24C02 驱动程序）
最编程
2024-03-13 10:12:08
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#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/log2.h>
#include <linux/bitops.h>
#include <linux/jiffies.h>
#include <linux/of.h>
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <asm/uaccess.h>
#define IOC_AT24C02_READ 100
#define IOC_AT24C02_WRITE 101
/* 主设备号 */
static int major = 0;
static struct class *at24c02_class;
struct i2c_client *at24c02_client;
static long at24c02_chrdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
unsigned char addr;
unsigned char data;
unsigned int ker_buf[2];
unsigned int *usr_buf = (unsigned int *)arg;
unsigned char byte_buf[2];
struct i2c_msg msgs[2];
copy_from_user(ker_buf, usr_buf, 8);
addr = ker_buf[0];
switch (cmd)
{
case IOC_AT24C02_READ:
{
/* 读AT24C02 */
msgs[0].addr = at24c02_client->addr;
msgs[0].flags = 0; /* 写 */
msgs[0].len = 1;
msgs[0].buf = &addr;
msgs[1].addr = at24c02_client->addr;
msgs[1].flags = I2C_M_RD; /* 读 */
msgs[1].len = 1;
msgs[1].buf = &data;
i2c_transfer(at24c02_client->adapter, msgs, 2);
ker_buf[1] = data;
copy_to_user(usr_buf, ker_buf, 8);
break;
}
case IOC_AT24C02_WRITE:
{
/* 写AT24C02 */
byte_buf[0] = addr;
byte_buf[1] = ker_buf[1];
msgs[0].addr = at24c02_client->addr;
msgs[0].flags = 0; /* 写 */
msgs[0].len = 2;
msgs[0].buf = byte_buf;
i2c_transfer(at24c02_client->adapter, msgs, 1);
mdelay(20);
break;
}
}
return 0;
}
/* 定义自己的file_operations结构体 */
static struct file_operations at24c02_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = at24c02_chrdev_ioctl,
};
static int at24c02_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
at24c02_client = client;
/* 注册file_operations */
major = register_chrdev(0, "100ask_at24c02", &at24c02_fops); /* /dev/at24c02 */
at24c02_class = class_create(THIS_MODULE, "100ask_at24c02_class");
if (IS_ERR(at24c02_class)) {
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
unregister_chrdev(major, "100ask_at24c02");
return PTR_ERR(at24c02_class);
}
device_create(at24c02_class, NULL, MKDEV(major, 0), NULL, "100ask_at24c02"); /* /dev/100ask_at24c02 */
return 0;
}
static int at24c02_remove(struct i2c_client *client)
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
device_destroy(at24c02_class, MKDEV(major, 0));
class_destroy(at24c02_class);
unregister_chrdev(major, "100ask_at24c02");
return 0;
}
static const struct of_device_id at24c02_of_match[] = {
{.compatible = "my,at24c02"},
{}
};
static const struct i2c_device_id at24c02_ids[] = {
{ "xxxxyyy", (kernel_ulong_t)NULL },
{ /* END OF LIST */ }
};
static struct i2c_driver at24c02_drv = {
.driver = {
.name = "myat24c02",
.of_match_table = at24c02_of_match,
},
.probe = at24c02_probe,
.remove = at24c02_remove,
.id_table = at24c02_ids,
};
/* 2. 在入口函数注册platform_driver */
static int __init at24c02_init(void)
{
int err;
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
return i2c_add_driver(&at24c02_drv);
return err;
}
/* 3. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数
* 卸载platform_driver
*/
static void __exit at24c02_exit(void)
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
i2c_del_driver(&at24c02_drv);
}
/* 7. 其他完善：提供设备信息，自动创建设备节点 */
module_init(at24c02_init);
module_exit(at24c02_exit);
MODULE_LICENSE("GPL");