8.Linux按键驱动-中断下半部

1.编程思路
1.1在gpio结构体中添加tasklet_struct结构体

1.2在probe函数中初始化tasklet结构体

1.3在中断服务程序中调度tasklet

1.4在这个函数中执行其它任务

2.代码：
应用程序和Makefile和上节一致

https://blog.csdn.net/weixin_40933496/article/details/143263990?sharetype=blogdetail&sharerId=143263990&sharerefer=PC&sharesource=weixin_40933496&spm=1011.2480.3001.8118

驱动

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/fcntl.h>/* 定义结构体来描述gpio */
struct gpio_key{int gpio;struct gpio_desc* gpiod;int flag;int irq;struct timer_list key_timer;struct tasklet_struct tasklet;
};/* 定义全局变量来存储设备树中的所有gpio节点信息 */
static struct gpio_key* gpio_keys_100ask;/* 字符设备的主设备号 */
static unsigned int major = 0;
static struct class *gpio_class;
//static int g_key = 0;/* 定义等待队列 */
static DECLARE_WAIT_QUEUE_HEAD(gpio_key_wait);
struct fasync_struct * button_fasync;/* 环形缓冲区 */
#define BUF_LEN 128
static int g_keys[BUF_LEN];
static int r, w;#define NEXT_POS(x) ((x+1) % BUF_LEN)int is_key_buf_empty(void)
{return (r == w);
}int is_key_buf_full(void)
{return (r == NEXT_POS(w));
}void put_key(int key)
{if (!is_key_buf_full()){g_keys[w] = key;w = NEXT_POS(w);}
}int get_key(void)
{int key = 0;if (!is_key_buf_empty()){key = g_keys[r];r = NEXT_POS(r);}return key;
}static ssize_t gpio_read(struct file *fp, char __user *buf, size_t size, loff_t * offset)
{int err;int key;if(is_key_buf_empty() && (fp->f_flags & O_NONBLOCK)){return -EAGAIN;}wait_event_interruptible(gpio_key_wait, !is_key_buf_empty());key = get_key();//err = copy_to_user(buf, &g_key, 4);err = copy_to_user(buf, &key, 4);//g_key = 0;//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 4;
}static unsigned int gpio_poll(struct file *fp, struct poll_table_struct *wait)
{//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);poll_wait(fp, &gpio_key_wait, wait);return is_key_buf_empty() ? 0 : POLLIN | POLLRDNORM;
}static int gpio_fasync(int fd , struct file *file, int on)
{//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);if (fasync_helper(fd, file, on, &button_fasync) >= 0){return 0;}else{return -EIO;}
}static const struct file_operations gpio_fops = {.owner = THIS_MODULE,.read  = gpio_read,.poll  = gpio_poll,.fasync = gpio_fasync,
};static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{struct gpio_key* gpio_key = dev_id;//int val;//int key;//val = gpio_get_value(gpio_key->gpio);//printk("key %d %d\n", gpio_key->gpio, val);//g_key = (gpio_key->gpio << 8) | val;//key = (gpio_key->gpio << 8) | val;//put_key(key);//wake_up_interruptible(&gpio_key_wait);/* 发信号 *///kill_fasync(&button_fasync, SIGIO, POLL_IN);//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);/* 调度tasklet函数 */tasklet_schedule(&gpio_key->tasklet);/* 修改定时器超时时间 */printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);mod_timer(&gpio_key->key_timer, jiffies + HZ / 5);return IRQ_HANDLED;
}/* 定时器超时函数 */
static void key_timer_expire(unsigned long arg)
{struct gpio_key* gpio_key = arg;int val;int key;val = gpio_get_value(gpio_key->gpio);//printk("key %d %d\n", gpio_key->gpio, val);//g_key = (gpio_key->gpio << 8) | val;key = (gpio_key->gpio << 8) | val;put_key(key);wake_up_interruptible(&gpio_key_wait);/* 发信号 */kill_fasync(&button_fasync, SIGIO, POLL_IN);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);/* 修改定时器超时时间 *///mod_timer(&gpio_key->key_timer, jiffies + HZ / 5);
}/* tasklet处理函数 */
static void key_tasklet_func(unsigned long data)
{struct gpio_key* key = data;int val;val = gpio_get_value(key->gpio);printk("进入了tasklet函数\n");printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);printk("key %d value is %d\n", key->gpio, val);
}static int gpio_probe(struct platform_device *pdev)
{int count, i;struct device_node *node;int err;node = pdev->dev.of_node;count = of_gpio_count(node);if (!count){printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);return -1;}/* 申请资源 */gpio_keys_100ask = kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL);if (!gpio_keys_100ask){printk("kzalloc error\n");return -1;}/* 获得资源 */for (i = 0; i < count; i++){gpio_keys_100ask[i].gpio = of_get_gpio(node, i);if (gpio_keys_100ask[i].gpio < 0){printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__);return -1;}gpio_keys_100ask[i].gpiod = gpio_to_desc(gpio_keys_100ask[i].gpio);gpio_keys_100ask[i].irq   = gpio_to_irq(gpio_keys_100ask[i].gpio);/* 申请中断 */err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "test1_gpio_keys_100ask", &gpio_keys_100ask[i]);if (err) {printk("request_irq err\n");}/* 设置定时器 */setup_timer(&gpio_keys_100ask[i].key_timer, key_timer_expire, &gpio_keys_100ask[i]);//设置定时器超时时间为无穷gpio_keys_100ask[i].key_timer.expires = ~0;/* 添加定时器 */add_timer(&gpio_keys_100ask[i].key_timer);/* 初始化tasklet */tasklet_init(&gpio_keys_100ask[i].tasklet, key_tasklet_func, &gpio_keys_100ask[i]);}/* 注册字符设备 */major = register_chrdev(major, "100ask_key", &gpio_fops);if(major < 0){printk("register_chrdev err'\n");return -1;}/* 注册类 */gpio_class = class_create(THIS_MODULE, "100ask_key_class");/* 注册设备 */device_create(gpio_class, NULL, MKDEV(major,0), NULL, "100ask_key_button");printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}static int gpio_remove(struct platform_device *pdev)
{int count, i;struct device_node *node;node = pdev->dev.of_node;count = of_gpio_count(node);device_destroy(gpio_class, MKDEV(major,0));class_destroy(gpio_class);unregister_chrdev(major, "100ask_key");for (i = 0; i < count; i++){free_irq(gpio_keys_100ask[i].irq, &gpio_keys_100ask[i]);}kfree(gpio_keys_100ask);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}/*
* 在设备树中添加的节点的compatible属性为："test1_100ask,test1_gpio_key"
*/
static const struct of_device_id gpio_key_of_match[] = {{.compatible = "test1_100ask,test1_gpio_key"},{/* 这里必须要有一个空项，表示结束 */}
};static struct platform_driver gpio_driver = {.driver = {.name	= "test1_gpio_keys_100ask",.of_match_table = gpio_key_of_match,},.probe	= gpio_probe,.remove = gpio_remove,
};/* 基于platform总线来实现这个程序 */
static int gpio_init(void)  
{int ret;ret = platform_driver_register(&gpio_driver);if (ret != 0){printk("platform_driver_register err\n");return -1;}else{printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);}return ret;
}static void gpio_exit(void)
{platform_driver_unregister(&gpio_driver);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
}module_init(gpio_init);
module_exit(gpio_exit);
MODULE_LICENSE("GPL");

3.运行结果

由运行结果可知，在驱动中检测到两次按键按压事件(tasklet函数被调用两次)，由于上节中的定时器消抖，导致key_timer_expire函数只被调用了一次，故read函数只执行了一次，应用程序只能获取后一个按键值。
4.代码路径

/home/book/nfs_rootfs/CSDN/01_gpio_irq/08_read_key_irq_poll_fasync_block_timer_tasklet