AM625: 字符设备驱动的使用：内核无法使用of_get_named_gpio获取，请问当前内核不支持字符设备驱动硬件吗？还是通过什么地方配置支持，还是怎么办

我咨询一下相关工程师再给你回复。

请问是想要获取gpio number吗？

您是修改的哪个内核驱动程序？

这个 gpio 的设备树设置是什么？

这是设备树的pinctrl:

led6254 {
compatible = "led6254";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&usr_led6254_pins_default>;
led6254-gpio = <&main_gpio1 16 GPIO_ACTIVE_LOW>;
};

这是设备树的pinctrl:

usr_led6254_pins_default: usr-led6254-pins-default{
pinctrl-single,pins = <
AM62X_IOPAD(0X1B8,PIN_OUTPUT,7)
>;
};

这个是驱动代码：我想用字符设备方式来驱动gpio

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/irq.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/platform_device.h>
//#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#define LEDDEV_CNT 1
#define LEDDEV_NAME "dtsplatled"
#define LEDOFF 0
#define LEDON 1

struct leddev_dev{
dev_t devid; /* 设备号 */
struct cdev cdev; /* cdev */
struct class *class; /* 类 */
struct device *device; /* 设备 */
int major; /* 主设备号 */
struct device_node *node; /* LED设备节点 */
int led0; /* LED灯GPIO标号 */
};

struct leddev_dev leddev; /* led设备 */

/*
* @description : LED打开/关闭
* @param - sta : LEDON(0) 打开LED，LEDOFF(1) 关闭LED
* @return : 无
*/
void led0_switch(u8 sta)
{
if (sta == LEDON )
gpio_set_value(leddev.led0, 0);
else if (sta == LEDOFF)
gpio_set_value(leddev.led0, 1);
}

static int led_open(struct inode *inode, struct file *filp)
{
filp->private_data = &leddev; /* 设置私有数据 */
return 0;
}

static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offt)
{
int retvalue;
unsigned char databuf[2];
unsigned char ledstat;

retvalue = copy_from_user(databuf, buf, cnt);
if(retvalue < 0) {

printk("kernel write failed!\r\n");
return -EFAULT;
}

ledstat = databuf[0];
if (ledstat == LEDON) {
led0_switch(LEDON);
} else if (ledstat == LEDOFF) {
led0_switch(LEDOFF);
}
return 0;
}

static struct file_operations led_fops = {
.owner = THIS_MODULE,
.open = led_open,
.write = led_write,
};

static int led_probe(struct platform_device *dev)
{
printk("led driver and device was matched!\r\n");
/* 1、设置设备号 */
if (leddev.major) {
leddev.devid = MKDEV(leddev.major, 0);
register_chrdev_region(leddev.devid, LEDDEV_CNT, LEDDEV_NAME);
} else {
alloc_chrdev_region(&leddev.devid, 0, LEDDEV_CNT, LEDDEV_NAME);
leddev.major = MAJOR(leddev.devid);
}

/* 2、注册设备 */
cdev_init(&leddev.cdev, &led_fops);
cdev_add(&leddev.cdev, leddev.devid, LEDDEV_CNT);

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

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

/* 5、初始化IO */

//驱动编译后能找到节点

leddev.node = of_find_node_by_path("/led6254");
if (leddev.node == NULL){
printk("gpioled node nost find!\r\n");
return -EINVAL;
}
else{
printk("led6254 find !\r\n");
}

//驱动编译后不能通过of_get_named_gpio();函数找打引脚，启动日志显示 -22
leddev.led0 = of_get_named_gpio(leddev.node, "led6254-gpio", 0);
if (leddev.led0 < 0) {
printk("can't get led6254-gpio\r\n");
return -EINVAL;
}
else{
printk("led6254 get!\r\n");
}

gpio_request(leddev.led0, "led0");
gpio_direction_output(leddev.led0, 1); /* led0 IO设置为输出，默认高电平 */
return 0;
}

/*
* @description : platform驱动的remove函数，移除platform驱动的时候此函数会执行
* @param - dev : platform设备
* @return : 0，成功;其他负值,失败
*/
static int led_remove(struct platform_device *dev)
{
gpio_set_value(leddev.led0, 1); /* 卸载驱动的时候关闭LED */
gpio_free(leddev.led0); /* 释放IO */

cdev_del(&leddev.cdev); /* 删除cdev */
unregister_chrdev_region(leddev.devid, LEDDEV_CNT); /* 注销设备号 */
device_destroy(leddev.class, leddev.devid);
class_destroy(leddev.class);
return 0;
}

static const struct of_device_id led_of_match[] = {
{ .compatible = "led6254" },
{ /* Sentinel */ }
};

static struct platform_driver led_driver = {
.driver = {
.name = "imx6ul-led", /* 驱动名字，用于和设备匹配 */
.of_match_table = led_of_match, /* 设备树匹配表 */
},
.probe = led_probe,
.remove = led_remove,
};

static int __init leddriver_init(void)
{
return platform_driver_register(&led_driver);
}

/*
* @description : 驱动模块卸载函数
* @param : 无
* @return : 无
*/
static void __exit leddriver_exit(void)
{
platform_driver_unregister(&led_driver);
}

module_init(leddriver_init);
module_exit(leddriver_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("lee");

请参考以下回复：

The kernel already has a led driver

The GPIO based led driver is drivers/leds/leds-gpio.c.

For the device tree configuration, you can refer to the "leds" node in k3-am62a7-sk.dts.