一、杂项设备驱动
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/device.h>
#include <asm/io.h>
#include <asm/string.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>#define DEV_NAME "led"
#define GPBCON 0x56000010
#define GPBDAT 0x56000014static volatile unsigned long * gpbcon;
static volatile unsigned long * gpbdat;static void init_led(void)
{// 配置GPB5引脚功能为输出*gpbcon &= ~(3 << 10);*gpbcon |= (1 << 10);// 将GPB5引脚电平置高*gpbdat |= (1 << 5);
}static void led_on(void)
{// 将GPB5引脚电平置低*gpbdat &= ~(1 << 5);
}static void led_off(void)
{// 将GPB5引脚电平置高*gpbdat |= (1 << 5);
}static int open (struct inode *inode, struct file *file)
{init_led();printk("open..\n");return 0;
}static ssize_t read (struct file * file, char __user * buf, size_t len, loff_t * offset)
{printk("read..\n");return 0;
}static ssize_t write (struct file * file, const char __user * buf, size_t len, loff_t *offset)
{unsigned char data[12] = {0};size_t len_cp = sizeof(data) < len ? sizeof(data) : len;copy_from_user(data, buf, len_cp);if (!strcmp(data,"ledon")){led_on();}else if (!strcmp(data,"ledoff")){led_off();}elsereturn -EINVAL;printk("write..\n");return len_cp;
}static int close (struct inode * inode, struct file * file)
{printk("close..\n");return 0;
}static struct file_operations fops =
{.owner = THIS_MODULE,.open = open,.read = read,.write = write,.release = close
};//struct class *class;
//struct device *device;static struct miscdevice misc_device_node =
{.minor = MISC_DYNAMIC_MINOR,.name = DEV_NAME,.fops = &fops
};static int __init led_init(void)
{int ret = 0;
// class = class_create(THIS_MODULE,"led");ret = misc_register(&misc_device_node);if (ret < 0)goto err_misc_register;gpbcon = ioremap(GPBCON,sizeof(*gpbcon));//映射一个地址gpbdat = ioremap(GPBDAT,sizeof(*gpbdat));// device = device_create(class,NULL,dev,NULL,"led");printk("led_init ------------------------\n");return ret;err_misc_register:misc_deregister(&misc_device_node);printk("led misc_register failed\n");return ret;
}static void __exit led_exit(void)
{
// device_destroy(class,dev);iounmap(gpbcon);//解除一个地址iounmap(gpbdat);
// class_destroy(class);misc_deregister(&misc_device_node);printk("led_exit ----------------------------\n");
}module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
- 新建一个led_misc.c 代码修改内容如上
- 修改Makefile
- make menuconfig，新选项LED_MISC选中<M>
- make modules
- cp drivers/char/led_misc.ko /home/linux/nfs/rootfs
- 开发板 insmod led_misc.ko
- 开发板 ls /dev -l 查看led设备是否生成
- 开发板 ./led_app 运行程序
二、自动创建设备节点
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/kdev_t.h>
#include <linux/cdev.h>
#include <linux/module.h>
#include <asm/io.h>
#include <asm/string.h>
#include <asm/uaccess.h>
#include <linux/device.h>#define MAJOR_NUM 253
#define MINOR_NUM 0
#define DEV_NAME "led"
#define DEV_NUM 1
#define GPBCON 0x56000010
#define GPBDAT 0x56000014static volatile unsigned long * gpbcon;
static volatile unsigned long * gpbdat;static void init_led(void)
{// 配置GPB5引脚功能为输出*gpbcon &= ~(0xff << 10);*gpbcon |= (0x55 << 10);// 将GPB5引脚电平置高*gpbdat |= (0xf << 5);
}static void led_on(void)
{// 将GPB5引脚电平置低*gpbdat &= ~(0xf << 5);
}static void led_off(void)
{// 将GPB5引脚电平置高*gpbdat |= (0xf << 5);
}static int open (struct inode * inode, struct file * file)
{init_led();printk("led open ...\n");return 0;
}static ssize_t read (struct file * file, char __user * buf, size_t len, loff_t * offset)
{//copy_to_user(buf, data, len);printk("led read ...\n");return 0;
}static ssize_t write (struct file * file, const char __user * buf, size_t len, loff_t * offset)
{unsigned char data[12] = {0};size_t len_cp = sizeof(data) < len ? sizeof(data) : len;copy_from_user(data, buf, len_cp);if(!strcmp(data, "ledon"))led_on();else if(!strcmp(data, "ledoff"))led_off();elsereturn -1;printk("led write ...\n");return len_cp;
}static int close (struct inode * inode, struct file * file)
{printk("led close ...\n");return 0;
}static struct file_operations fops =
{.owner = THIS_MODULE,.open = open,.read = read,.write = write,.release = close
};
static struct cdev cdev;
static dev_t dev;
struct class * pclass;
struct device * pdev;static int __init led_init(void)
{int ret = 0;dev = MKDEV(MAJOR_NUM, MINOR_NUM);cdev_init(&cdev, &fops);ret = cdev_add(&cdev, dev, DEV_NUM);if(ret < 0)goto err_cdev_add;ret = register_chrdev_region(dev, DEV_NUM, DEV_NAME);if(ret < 0)goto err_register_chrdev_region;pclass = class_create(THIS_MODULE, "led_class");if(pclass == NULL)goto err_class_create;pdev = device_create(pclass, NULL, dev, NULL, DEV_NAME);if(pdev == NULL)goto err_device_create;gpbcon = ioremap(GPBCON, sizeof(*gpbcon));gpbdat = ioremap(GPBDAT, sizeof(*gpbdat));printk("led_init ...\n");return ret;err_cdev_add:cdev_del(&cdev);printk("led cdev_add failed\n");return ret;err_register_chrdev_region:unregister_chrdev_region(dev, DEV_NUM);cdev_del(&cdev);printk("led register_chrdev_region failed\n"); return ret;err_class_create:class_destroy(pclass);unregister_chrdev_region(dev, DEV_NUM);cdev_del(&cdev);printk("led class_create failed\n"); return -1;err_device_create:device_destroy(pclass, dev);class_destroy(pclass);unregister_chrdev_region(dev, DEV_NUM);cdev_del(&cdev);printk("led device_create failed\n"); return -1;
}static void __exit led_exit(void)
{iounmap(gpbcon);iounmap(gpbdat);device_destroy(pclass, dev);class_destroy(pclass);unregister_chrdev_region(dev, DEV_NUM);cdev_del(&cdev);printk("led_exit ###############################\n");
}module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");三、GPIO子系统
