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青岛做网站的公司有哪些,筑巢网站,网站建设定制开发,廊坊企业网站团队Rk3588鲁班猫4点亮led这里只上代码#xff0c;先执行sudo sh -c echo 0 /sys/class/leds/sys_status_led/brightness关闭自带一直闪烁的led。随后编译下面代码得到.ko文件并加载到板卡。Makefile文件可以看我上一篇博客的末尾。#include linux/init.h#include 先执行sudo sh -c echo 0 /sys/class/leds/sys_status_led/brightness关闭自带一直闪烁的led。随后编译下面代码得到.ko文件并加载到板卡。Makefile文件可以看我上一篇博客的末尾。#include linux/init.h #include linux/module.h #include linux/cdev.h #include linux/fs.h #include linux/uaccess.h #include linux/io.h #define DEV_NAME led_chrdev #define DEV_CNT (1) #define GPIO4_BASE (0xFEC50000) #define GPIO4_DR_L (GPIO4_BASE 0x0000) #define GPIO4_DDR_L (GPIO4_BASE 0x0008) static dev_t devno; struct class *led_chrdev_class; struct led_chrdev { struct cdev dev; unsigned int __iomem *va_dr; // 数据寄存器设置输出的电压 unsigned int __iomem *va_ddr; // 数据方向寄存器设置输入或者输出 unsigned int led_pin; // 偏移 }; static int led_chrdev_open(struct inode *inode, struct file *filp) { unsigned int val 0; struct led_chrdev *led_cdev (struct led_chrdev *)container_of(inode-i_cdev, struct led_chrdev,dev); filp-private_data container_of(inode-i_cdev, struct led_chrdev, dev); printk(open\n); //设置输出模式 val ioread32(led_cdev-va_ddr); val | ((unsigned int)0x1 (led_cdev-led_pin16)); val | ((unsigned int)0X1 (led_cdev-led_pin)); iowrite32(val,led_cdev-va_ddr); //输出高电平 val ioread32(led_cdev-va_dr); val | ((unsigned int)0x1 (led_cdev-led_pin16)); val | ((unsigned int)0x1 (led_cdev-led_pin)); iowrite32(val, led_cdev-va_dr); return 0; } static int led_chrdev_release(struct inode *inode, struct file *filp) { return 0; } static ssize_t led_chrdev_write(struct file *filp, const char __user * buf, size_t count, loff_t * ppos) { unsigned long val 0; unsigned long copy_ret0; char ret 0; struct led_chrdev *led_cdev (struct led_chrdev *)filp-private_data; printk(write \n); copy_retcopy_from_user(ret, buf, 1); if (copy_ret ! 0) { printk(KERN_ERR led_chrdev: copy_from_user failed, uncopied: %lu\n, copy_ret); return -EFAULT; // 返回错误码告知用户空间读取失败 } val ioread32(led_cdev-va_dr); printk(val %lx\n, val); if (ret 0){ val | ((unsigned int)0x1 (led_cdev-led_pin16)); val ~((unsigned int)0x01 (led_cdev-led_pin)); /*设置GPIO引脚输出低电平*/ } else{ val | ((unsigned int)0x1 (led_cdev-led_pin16)); val | ((unsigned int)0x01 (led_cdev-led_pin)); /*设置GPIO引脚输出高电平*/ } iowrite32(val, led_cdev-va_dr); printk(val %lx\n, val); return count; } static struct file_operations led_chrdev_fops { .owner THIS_MODULE, .open led_chrdev_open, .release led_chrdev_release, .write led_chrdev_write, }; static struct led_chrdev led_cdev[DEV_CNT] { {.led_pin 13}, }; static __init int led_chrdev_init(void) { int i 0; dev_t cur_dev; printk(led_chrdev init (lubancat2 GPIO4_B5)\n); led_cdev[0].va_dr ioremap(GPIO4_DR_L, 4); led_cdev[0].va_ddr ioremap(GPIO4_DDR_L, 4); alloc_chrdev_region(devno, 0, DEV_CNT, DEV_NAME); led_chrdev_class class_create(THIS_MODULE, led_chrdev); for (; i DEV_CNT; i) { cdev_init(led_cdev[i].dev, led_chrdev_fops); led_cdev[i].dev.owner THIS_MODULE; cur_dev MKDEV(MAJOR(devno), MINOR(devno) i); cdev_add(led_cdev[i].dev, cur_dev, 1); device_create(led_chrdev_class, NULL, cur_dev, NULL, DEV_NAME %d, i); } return 0; } module_init(led_chrdev_init); static __exit void led_chrdev_exit(void) { int i; dev_t cur_dev; printk(led chrdev exit (lubancat2 GPIO4_B5)\n); for (i 0; i DEV_CNT; i) { iounmap(led_cdev[i].va_dr); // 释放模式寄存器虚拟地址 iounmap(led_cdev[i].va_ddr); // 释放输出类型寄存器虚拟地址 } for (i 0; i DEV_CNT; i) { cur_dev MKDEV(MAJOR(devno), MINOR(devno) i); device_destroy(led_chrdev_class, cur_dev); cdev_del(led_cdev[i].dev); } class_destroy(led_chrdev_class); unregister_chrdev_region(devno, DEV_CNT); } module_exit(led_chrdev_exit); MODULE_AUTHOR(embedfire); MODULE_LICENSE(GPL);之后执行下面语句就可以看到板卡的led点亮和关闭了。#绿灯亮 sudo sh -c echo 0 /dev/led_chrdev0 #绿灯灭 sudo sh -c echo 1 /dev/led_chrdev0