Linux 驱动——Button驱动1

button_drv.c驱动文件：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h> 　　　　 　　　　 //包含iomap函数iounmap函数
#include <asm/uaccess.h> 　　 　　   //包含copy_from_user函数
#include <linux/device.h> 　　 　　  //包含class类相关的处理函数
#include <linux/fs.h> 　　　　 　　   //包含file_operations结构体

#define DRIVER_NAME "button_drv"
#define DEVICE_NAME "button_dev"

int major;

static struct class *buttondrv_class;
static struct class_device *buttondrv_class_dev;

volatile unsigned long *gpfcon = NULL;
volatile unsigned long *gpfdat = NULL;
volatile unsigned long *gpgcon = NULL;
volatile unsigned long *gpgdat = NULL;

static int button_drv_open(struct inode *inode, struct file *file)
{
　　*gpfcon &= ~((0x3<<(0*2)) | (0x3<<(2*2)));
　　*gpgcon &= ~((0x3<<(3*2)) | (0x3<<(11*2)));
　　return 0;
}

static int button_drv_read(struct file * file, char __user * userbuf, size_t count, loff_t * off)
{
　　int ret;
　　unsigned char keyVal[4];
　　unsigned long keyVals;

　　if(count!=sizeof(keyVal))
　　{
　　　　printk("button_drv_read error 1 \n");
　　}

　　keyVals = *gpfdat;
　　keyVal[0] = ((keyVals>>0) & 1);
　　keyVal[1] = ((keyVals>>2) & 1);
　　keyVals = *gpgdat;
　　keyVal[2] = ((keyVals>>3) & 1);
　　keyVal[3] = ((keyVals>>11) & 1);
　　
　　ret = copy_to_user(userbuf, keyVal, sizeof(keyVal));
　　if(ret<0)
　　{
　　　　printk("button_drv_read error 2 \n");
　　}

　　return sizeof(keyVal);
}

static struct file_operations button_drv_fops = {
　　.owner = THIS_MODULE,
　　.open = button_drv_open,
　　.read = button_drv_read,
};

static int button_drv_init(void)
{
　　major = register_chrdev(0, DRIVER_NAME, &button_drv_fops);

　　buttondrv_class = class_create(THIS_MODULE, DEVICE_NAME);
　　buttondrv_class_dev = class_device_create(buttondrv_class, NULL, MKDEV(major, 0), NULL, DEVICE_NAME);

　　gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
　　gpfdat = gpfcon + 1;
　　gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
　　gpgdat = gpgcon + 1;
　　return 0;
}

static void button_drv_exit(void)
{
　　unregister_chrdev(major, DRIVER_NAME);
　　class_device_unregister(buttondrv_class_dev);
　　class_destroy(buttondrv_class);
　　iounmap(gpfcon);
　　iounmap(gpgcon);
}

module_init(button_drv_init);
module_exit(button_drv_exit);

MODULE_LICENSE("GPL");

Makefile文件：

obj-m += button_drv.o

KERN_DIR = /work/system/linux-2.6.22.6

all:
make -C $(KERN_DIR) M=`pwd` modules
clean:
rm -rf *.o *.ko *.order *.symvers *.mod.c

button_app.c文件:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

int main(int argc, char **argv)
{
　　int fd;
　　int val;
　　char *filename;
　　unsigned char keyVal[4];

　　filename = argv[1];
　　fd = open(filename, O_RDWR);
　　if(fd<0)
　　{
　　　　printf("can not open \n");
　　}

　　while(1)
　　{
　　　　read(fd, keyVal, sizeof(keyVal));
　　　　if(!keyVal[0] || !keyVal[1] || !keyVal[2] || !keyVal[3])
　　　　{
　　　　　　printf("key pressed %d %d %d %d \n", keyVal[0], keyVal[1], keyVal[2], keyVal[3]);
　　　　}
　　}

　　return 0;
}

编译生成button_drv.ko文件和button_app文件，运行：./button_app /dev/button_dev

原文地址：https://www.cnblogs.com/lian-meng/p/10509706.html