上次用的是节点搜索，这次用platform形式的

首先是设备树

/ {
	model = "Luckfox Pico Max";
	compatible = "rockchip,rv1103g-38x38-ipc-v10", "rockchip,rv1106";

	
    gpio1pc7:gpio1pc7 {
        compatible = "gpio1_pc7";
        pinctrl-names = "default";
		status = "okay";
        pinctrl-0 = <&gpio1_pc7>;
		gpios = <&gpio1 RK_PC7 GPIO_ACTIVE_HIGH>;
        regulator-name = "gpio1_pc7";
        regulator-always-on;
    };
};


/* GPIO */
&pinctrl {
    gpio1-pc7 {
        gpio1_pc7:gpio1-pc7 {
            rockchip,pins = <1 RK_PC7 RK_FUNC_GPIO &pcfg_pull_none>;
        };
    };
};

然后就是根据设备树，编写驱动代码

#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/cdev.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <asm/uaccess.h>

#define GPIO_CNT 1
#define GPIO_NAME "gpio1_pc7"

struct gpio1_pc7_dev
{
	dev_t devid;
	struct cdev cdev;
	struct class *class;
	struct device *device;
	int major;
	int minor;
	struct device_node *nd;
	int gpio1_pc7;
};

struct gpio1_pc7_dev gpio1_pc7;

static int gpio1_pc7_open(struct inode *inode,struct file *filp)
{
	/* 设置为私有数据 */
	filp->private_data = &gpio1_pc7;
	return 0;
}

static int gpio1_pc7_read(struct file *filp,char __user *buf,size_t cnt,loff_t *offt)
{
	return 0;
}

static ssize_t gpio1_pc7_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
	int ret;
	unsigned char databuf[1];
	unsigned char ledstat;
	struct gpio1_pc7_dev *dev = filp->private_data;

	ret = copy_from_user(databuf, buf, cnt);
	if(ret<0)
	{
		printk("kernel write failed
");
		return -EFAULT;
	}
	ledstat = databuf[0];
	if(ledstat == 1)
	{
		gpio_set_value(dev->gpio1_pc7,1);
	}
	else if(ledstat == 0)
	{
		gpio_set_value(dev->gpio1_pc7,0);
	}
	return 0;
}
static int gpio1_pc7_release(struct inode *inode,struct file *flip)
{
	return 0;
}
static struct file_operations gpio1_pc7_fops = {
	.owner = THIS_MODULE,
	.open = gpio1_pc7_open,
	.read = gpio1_pc7_read,
	.write = gpio1_pc7_write,
	.release = gpio1_pc7_release,
};

static int gpio1_pc7_probe(struct platform_device *dev)
{
	int ret = 0;
	printk("gpio1_pc7 driver and device was matched
");

	/* 1、设置设备号 */
	if(gpio1_pc7.major)
	{
		gpio1_pc7.devid = MKDEV(gpio1_pc7.major,0);
		ret = register_chrdev_region(gpio1_pc7.devid,GPIO_CNT,GPIO_NAME);
	}
	else
	{
		alloc_chrdev_region(&gpio1_pc7.devid,0,GPIO_CNT,GPIO_NAME);/* 申请设备号 */
		gpio1_pc7.major = MAJOR(gpio1_pc7.devid);
		gpio1_pc7.minor = MINOR(gpio1_pc7.devid);
	}

	printk("gpio1_pc7 major = %dgpio1_pc7_init,minor=%d
",gpio1_pc7.major,gpio1_pc7.minor);

	//gpio1_pc7.cdev.owner = THIS_MODULE;
	/* 2、注册设备 */
	cdev_init(&gpio1_pc7.cdev,&gpio1_pc7_fops);
	cdev_add(&gpio1_pc7.cdev,gpio1_pc7.devid,GPIO_CNT);

	/* 3、创建类 */
	gpio1_pc7.class = class_create(THIS_MODULE,GPIO_NAME);
	if(IS_ERR(gpio1_pc7.class))
	{
		return PTR_ERR(gpio1_pc7.class);
	}

	/* 4、创建设备 */
	gpio1_pc7.device = device_create(gpio1_pc7.class, NULL, gpio1_pc7.devid, NULL, GPIO_NAME);
	if(IS_ERR(gpio1_pc7.device))
	{
		return PTR_ERR(gpio1_pc7.device);
	}

	/* 5、初始化IO */
	gpio1_pc7.nd = of_find_node_by_path("/gpio1pc7");
	if(gpio1_pc7.nd == NULL)
	{
		printk("gpio1pc7 node can't not found
");
		return -EINVAL;
	}
	else
	{
		printk("gpio1pc7 node has been found
");
	}

	gpio1_pc7.gpio1_pc7 = of_get_named_gpio(gpio1_pc7.nd,"gpios",0);
	if(gpio1_pc7.gpio1_pc7 < 0)
	{
		printk("can't get gpio1_pc7
");
		return -EINVAL;
	}
	printk("gpio1_pc7 num = %d
", gpio1_pc7.gpio1_pc7);

	/* 8、请求GPIO，设置输出 */
	ret = gpio_request(gpio1_pc7.gpio1_pc7,GPIO_NAME);
	if(ret)
	{
		printk("can't request gpio
");
	}
	ret = gpio_direction_output(gpio1_pc7.gpio1_pc7,1);
	if(ret < 0)
	{
		printk("can't set gpio
");
	}
	return 0;
}

static int gpio1_pc7_remove(struct platform_device *dev)
{
	gpio_free(gpio1_pc7.gpio1_pc7);
	/* 删除cdev */
	cdev_del(&gpio1_pc7.cdev);
	/* 注销 */
	unregister_chrdev_region(gpio1_pc7.devid, GPIO_CNT);
	device_destroy(gpio1_pc7.class, gpio1_pc7.devid);
	class_destroy(gpio1_pc7.class);
	return 0;
}

/* 匹配列表 */
static const struct of_device_id gpio_of_match[] = 
{
	{ .compatible = "gpio1_pc7" },
	//{ .status = "gpio1_pc7" },
	{},
};

MODULE_DEVICE_TABLE(of, gpio_of_match);

/* platform驱动结构体 */
static struct platform_driver gpio1_pc7_driver = 
{
	.driver =
	{
		.name = GPIO_NAME,			/* 驱动名字 */
		.of_match_table = gpio_of_match,	/* 设备树匹配表 */
	},
	.probe = gpio1_pc7_probe,
	.remove = gpio1_pc7_remove,
};

static int __init gpio1_pc7_init(void)
{
	return platform_driver_register(&gpio1_pc7_driver);
}

static void __exit gpio1_pc7_exit(void)
{
	platform_driver_unregister(&gpio1_pc7_driver);
}

module_init(gpio1_pc7_init);
module_exit(gpio1_pc7_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Luckfox");
MODULE_VERSION("V1.0");

上面是通过.compatible来搜索关键信息，找到设备树的节点

最后载入驱动

# insmod gpio_platform.ko
# dmesg

运用insmod载入，然后运用dmesg来查看内核打印的消息