【学习日记】【第五十一章 Linux中断实验】【流程图】——正点原子I.MX6U嵌入式Linux驱动开发

1 概述

本文主要是笔者根据《正点原子I.MX6U嵌入式Linux驱动开发》中 “第五十一章 Linux中断实验” 的程序绘制的流程图，方便理解中断和定时器的使用。

2 流程图

3 正点原子的代码

3.1 驱动程序

#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.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/of_irq.h>
#include <linux/irq.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>#define IMX6UIRQ_CNT 1 /* 设备号个数 */
#define IMX6UIRQ_NAME "imx6uirq" /* 名字 */
#define KEY0VALUE 0X01 /* KEY0 按键值 */
#define INVAKEY 0XFF /* 无效的按键值 */
#define KEY_NUM 1 /* 按键数量 *//* 中断 IO 描述结构体 */
struct irq_keydesc {int gpio; /* gpio */int irqnum; /* 中断号 */unsigned char value; /* 按键对应的键值 */char name[10]; /* 名字 */irqreturn_t (*handler)(int, void *); /* 中断服务函数 */
};/* imx6uirq 设备结构体 */
struct imx6uirq_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 */int minor; /* 次设备号 */struct device_node *nd; /* 设备节点 */atomic_t keyvalue; /* 有效的按键键值 */atomic_t releasekey; /* 标记是否完成一次完成的按键 */struct timer_list timer; /* 定义一个定时器 */struct irq_keydesc irqkeydesc[KEY_NUM]; /* 按键描述数组 */unsigned char curkeynum; /* 当前的按键号 */
};struct imx6uirq_dev imx6uirq; /* irq 设备 *//* 中断服务函数，开启定时器，延时 10ms，定时器用于按键消抖。 */
static irqreturn_t key0_handler(int irq, void *dev_id) {struct imx6uirq_dev *dev = (struct imx6uirq_dev *)dev_id;dev->curkeynum = 0;dev->timer.data = (volatile long)dev_id;mod_timer(&dev->timer, jiffies + msecs_to_jiffies(10));return IRQ_RETVAL(IRQ_HANDLED);
}/* 定时器服务函数，用于按键消抖 */
void timer_function(unsigned long arg) {unsigned char value;unsigned char num;struct irq_keydesc *keydesc;struct imx6uirq_dev *dev = (struct imx6uirq_dev *)arg;num = dev->curkeynum;keydesc = &dev->irqkeydesc[num];value = gpio_get_value(keydesc->gpio); /* 读取 IO 值 */if (value == 0) { /* 按下按键 */atomic_set(&dev->keyvalue, keydesc->value);} else { /* 按键松开 */atomic_set(&dev->keyvalue, 0x80 | keydesc->value);atomic_set(&dev->releasekey, 1); /* 标记松开按键 */}
}/* 按键 IO 初始化 */
static int keyio_init(void) {unsigned char i = 0;int ret = 0;imx6uirq.nd = of_find_node_by_path("/key");if (imx6uirq.nd == NULL) {printk("key node not find!\r\n");return -EINVAL;}/* 提取 GPIO */for (i = 0; i < KEY_NUM; i++) {imx6uirq.irqkeydesc[i].gpio = of_get_named_gpio(imx6uirq.nd, "key-gpio", i);if (imx6uirq.irqkeydesc[i].gpio < 0) {printk("can't get key%d\r\n", i);}}/* 初始化 key 所使用的 IO，并且设置成中断模式 */for (i = 0; i < KEY_NUM; i++) {memset(imx6uirq.irqkeydesc[i].name, 0, sizeof(imx6uirq.irqkeydesc[i].name));sprintf(imx6uirq.irqkeydesc[i].name, "KEY%d", i);gpio_request(imx6uirq.irqkeydesc[i].gpio, imx6uirq.irqkeydesc[i].name);gpio_direction_input(imx6uirq.irqkeydesc[i].gpio);imx6uirq.irqkeydesc[i].irqnum = irq_of_parse_and_map(imx6uirq.nd, i);printk("key%d:gpio=%d, irqnum=%d\r\n", i, imx6uirq.irqkeydesc[i].gpio, imx6uirq.irqkeydesc[i].irqnum);}/* 申请中断 */imx6uirq.irqkeydesc[0].handler = key0_handler;imx6uirq.irqkeydesc[0].value = KEY0VALUE;for (i = 0; i < KEY_NUM; i++) {ret = request_irq(imx6uirq.irqkeydesc[i].irqnum, imx6uirq.irqkeydesc[i].handler,IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,imx6uirq.irqkeydesc[i].name, &imx6uirq);if (ret < 0) {printk("irq %d request failed!\r\n", imx6uirq.irqkeydesc[i].irqnum);return -EFAULT;}}/* 创建定时器 */init_timer(&imx6uirq.timer);imx6uirq.timer.function = timer_function;return 0;
}/* 打开设备 */
static int imx6uirq_open(struct inode *inode, struct file *filp) {filp->private_data = &imx6uirq; /* 设置私有数据 */return 0;
}/* 从设备读取数据 */
static ssize_t imx6uirq_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt) {int ret = 0;unsigned char keyvalue = 0;unsigned char releasekey = 0;struct imx6uirq_dev *dev = (struct imx6uirq_dev *)filp->private_data;keyvalue = atomic_read(&dev->keyvalue);releasekey = atomic_read(&dev->releasekey);if (releasekey) { /* 有按键按下 */if (keyvalue & 0x80) {keyvalue &= ~0x80;ret = copy_to_user(buf, &keyvalue, sizeof(keyvalue));} else {goto data_error;}atomic_set(&dev->releasekey, 0); /* 按下标志清零 */} else {goto data_error;}return 0;data_error:return -EINVAL;
}/* 设备操作函数 */
static struct file_operations imx6uirq_fops = {.owner = THIS_MODULE,.open = imx6uirq_open,.read = imx6uirq_read,
};/* 驱动入口函数 */
static int __init imx6uirq_init(void) {/* 1、构建设备号 */if (imx6uirq.major) {imx6uirq.devid = MKDEV(imx6uirq.major, 0);register_chrdev_region(imx6uirq.devid, IMX6UIRQ_CNT, IMX6UIRQ_NAME);} else {alloc_chrdev_region(&imx6uirq.devid, 0, IMX6UIRQ_CNT, IMX6UIRQ_NAME);imx6uirq.major = MAJOR(imx6uirq.devid);imx6uirq.minor = MINOR(imx6uirq.devid);}/* 2、注册字符设备 */cdev_init(&imx6uirq.cdev, &imx6uirq_fops);cdev_add(&imx6uirq.cdev, imx6uirq.devid, IMX6UIRQ_CNT);/* 3、创建类 */imx6uirq.class = class_create(THIS_MODULE, IMX6UIRQ_NAME);if (IS_ERR(imx6uirq.class)) {return PTR_ERR(imx6uirq.class);}/* 4、创建设备 */imx6uirq.device = device_create(imx6uirq.class, NULL, imx6uirq.devid, NULL, IMX6UIRQ_NAME);if (IS_ERR(imx6uirq.device)) {return PTR_ERR(imx6uirq.device);}/* 5、 初始化按键 */atomic_set(&imx6uirq.keyvalue, INVAKEY);atomic_set(&imx6uirq.releasekey, 0);keyio_init();return 0;
}/* 驱动出口函数 */
static void __exit imx6uirq_exit(void) {unsigned int i = 0;/* 删除定时器 */del_timer_sync(&imx6uirq.timer);/* 释放中断 */for (i = 0; i < KEY_NUM; i++) {free_irq(imx6uirq.irqkeydesc[i].irqnum, &imx6uirq);gpio_free(imx6uirq.irqkeydesc[i].gpio);}cdev_del(&imx6uirq.cdev);unregister_chrdev_region(imx6uirq.devid, IMX6UIRQ_CNT);device_destroy(imx6uirq.class, imx6uirq.devid);class_destroy(imx6uirq.class);
}module_init(imx6uirq_init);
module_exit(imx6uirq_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zuozhongkai");

3.2 应用程序

#include "stdio.h"
#include "unistd.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "stdlib.h"
#include "string.h"
#include "linux/ioctl.h"/** @description : main 主程序* @param - argc : argv 数组元素个数* @param - argv : 具体参数* @return : 0 成功;其他 失败*/
int main(int argc, char *argv[])
{int fd;int ret = 0;char *filename;unsigned char data;if (argc != 2) {printf("Error Usage!\r\n");return -1;}filename = argv[1];fd = open(filename, O_RDWR);if (fd < 0) {printf("Can't open file %s\r\n", filename);return -1;}while (1) {ret = read(fd, &data, sizeof(data));if (ret < 0) { /* 数据读取错误或者无效 */// 处理错误} else { /* 数据读取正确 */if (data) /* 读取到数据 */printf("key value = %#X\r\n", data);}}close(fd);return ret;
}