input子系统的实现历程分享

刘先生11 · 发表于 2020-11-6 13:58:42

基于原子教程的input子系统的学习历程
修改部分为：由一个按键改为两个按键，涉及gpio的操作、定时器的初始化和注册等都有变动
学习所得：通过input子系统的学习，把按键、定时器、设备树又进行了一次复习，又有了不一样的理解，代码中我有加粗的部分，供大家参考。具体代码如下：
设备树部分如下：

mytest_key {
compatible = "mykey_gpio";
pinctrl-names = "default";
pinctrl-0 = <&myGPIO_key0
&myGPIO_key1>;
gpios = <&gpio5 1 GPIO_ACTIVE_LOW
&gpio4 14 GPIO_ACTIVE_LOW>;
};

复制代码

驱动部分：

#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/input.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 KEYINPUT_NAME "keyinput" /* 名字 */
#define KEY0VALUE 0X01 /* KEY0按键值 */
#define INVAKEY 0XFF /* 无效的按键值 */
#define KEY_NUM 2 /* 按键数量 */
struct irq_keydesc{
unsigned char value; /*键值*/
int gpio;
int flags;
struct gpio_desc *gpio_key;
int irqnum; /* 中断号 */
irqreturn_t (*handler)(int, void *); /* 中断服务函数 */
};
struct input_key_test{
dev_t devid; /* 设备号 */
struct cdev cdev; /* cdev */
struct class *class; /* 类 */
struct device *device; /* 设备 */
struct device_node *nd; /* 设备节点 */
struct irq_keydesc *irqkeydesc; /* 按键描述数组 */
struct timer_list timer; /* 定义一个定时器*/
unsigned char curkeynum; /* 当前的按键号 */
struct input_dev *inputdev; /* input结构体 */
};
static struct input_key_test keyinputdev;
static irqreturn_t key_handle0(int irq, void *dev_id)
{
struct input_key_test *dev = (struct input_key_test *)dev_id;
// printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
dev->timer.data = (unsigned long)dev_id;
dev->curkeynum =0;
mod_timer(&dev->timer , jiffies + HZ/5); /*延时去抖*/
return IRQ_HANDLED;
}
static irqreturn_t key_handle1(int irq, void *dev_id)
{
struct input_key_test *dev = (struct input_key_test *)dev_id;
// printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
dev->timer.data = (unsigned long)dev_id;
dev->curkeynum =1;
mod_timer(&dev->timer , jiffies + HZ/5); /*延时去抖*/
return IRQ_HANDLED;
}
static void timer_handle0(unsigned long arg)
{
int num;
int key;
struct input_key_test *dev = (struct input_key_test *)arg;
struct irq_keydesc *keydesc;
// printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
// printk("key num = %d\n",dev->curkeynum);
num = dev->curkeynum;
keydesc = &dev->irqkeydesc[num];
key = gpiod_get_value(keydesc->gpio_key );
// printk("key is %d\n",key);
if(key == 0){ /* 按下按键 */
/* 上报按键值 */
//input_event(dev->inputdev, EV_KEY, keydesc->value, 1);
input_report_key(dev->inputdev, keydesc->value, 1);/* 最后一个参数表示按下还是松开，1为按下，0为松开 */
input_sync(dev->inputdev);
} else { /* 按键松开 */
//input_event(dev->inputdev, EV_KEY, keydesc->value, 0);
input_report_key(dev->inputdev, keydesc->value, 0);
input_sync(dev->inputdev);
}
}
static int keyio_init(void)
{
int i;
int err;
int count;
enum of_gpio_flags flag;
/*获取设备树信息*/
keyinputdev.nd = of_find_node_by_path("/mytest_key"); /*获取设备节点*/
if(keyinputdev.nd == NULL)
{
printk("key node not find!\r\n");
return -1;
}
printk("keyinputdev.nd name is %s\n",keyinputdev.nd->name);
<div><b> count = of_gpio_count(keyinputdev.nd);//此处注意点：of_gpio_count在匹配设备树时，是匹配的gpios ，由于前期用的是gpiod_get这个函数，对应的设备树中需要写成“key-gpios”，所以我在这个地方被自己给坑了很久</b></div><div><b>//另外在写驱动的时候，对函数的返回值最好做判断，就比如对count我之前没有做判断（设备树中还是key-gpios），导致count的返回值是 -2,而我又没有对count的返回判断（即，没有下面的if(count<0)这个判断），加载模块就挂掉，内核反馈的错误</b></div><div><b>//代码也看不懂，只能重启，修改代码，测试，挂掉，重启......循环下去</b></div> <b></b><b></b>
if(count < 0)
{
printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);
return -1;
}
/*
内存分配
请求大小：gpio个数 * 一个结构体的大小
返回：申请内存的指针，正好给结构体指针
*/
keyinputdev.irqkeydesc = kmalloc(count * sizeof(struct irq_keydesc), GFP_KERNEL);
keyinputdev.irqkeydesc[0].handler = key_handle0;
keyinputdev.irqkeydesc[1].handler = key_handle1;
for(i=0 ;i<count;i++)
{
keyinputdev.irqkeydesc[i].gpio = of_get_gpio_flags(keyinputdev.nd, i, &flag); /*获取gpio*/
keyinputdev.irqkeydesc[i].gpio_key = gpio_to_desc(keyinputdev.irqkeydesc[i].gpio); /*由gpio转换为gpio_desc*/
keyinputdev.irqkeydesc[i].flags = flag & OF_GPIO_ACTIVE_LOW;
keyinputdev.irqkeydesc[i].irqnum = gpio_to_irq(keyinputdev.irqkeydesc[i].gpio);
//keyinputdev.irqkeydesc[i].handler = key_handle0;
/*注册中断*/
err = request_irq(keyinputdev.irqkeydesc[i].irqnum, keyinputdev.irqkeydesc[i].handler,IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "key_irq_test0", &keyinputdev);
if(err < 0)
{
printk("irq %d request failed!\r\n", keyinputdev.irqkeydesc[i].irqnum);
return -EFAULT;
}
}
keyinputdev.irqkeydesc[0].value =KEY_0;
keyinputdev.irqkeydesc[1].value =KEY_1;
/*设置定时器*/
setup_timer(&keyinputdev.timer , timer_handle0, (unsigned long)&keyinputdev);
keyinputdev.timer.expires = ~0 ;
add_timer(&keyinputdev.timer);
#if 0
init_timer(&keyinputdev.timer); //初始化定时器
keyinputdev.timer.function = timer_handle0; //设置定时器触发时函数
keyinputdev.timer.expires = ~0 ;
// add_timer(&keyinputdev.timer);
#endif
/* 申请input_dev */
keyinputdev.inputdev = input_allocate_device();
keyinputdev.inputdev->name = KEYINPUT_NAME;
keyinputdev.inputdev->evbit[0] = BIT_MASK(EV_KEY);
for(i=0 ;i<count;i++)
{
input_set_capability(keyinputdev.inputdev, EV_KEY, keyinputdev.irqkeydesc[i].value); /*设置keybit*/
}
/*注册input_dev*/
err = input_register_device(keyinputdev.inputdev);
return 0;
}
static int __init keyinput_init(void)
{
keyio_init();
return 0;
}
/*
* @description : 驱动出口函数
* [url=home.php?mod=space&uid=271674]@param[/url] : 无
* @return : 无
*/
static void __exit keyinput_exit(void)
{
int count;
unsigned int i = 0;
printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);
/*获取设备树信息*/
keyinputdev.nd = of_find_node_by_path("/mytest_key"); /*获取设备节点*/
count = of_gpio_count(keyinputdev.nd);
if(count < 0)
{
printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);
}
/* 删除定时器 */
#if 0
for(i=0 ;i<count;i++)
{
del_timer(&keyinputdev.irqkeydesc[i].timer ); /* 删除定时器 */
}
#endif
del_timer(&keyinputdev.timer ); /* 删除定时器 */
/* 释放中断 */
for (i = 0; i < count; i++) {
free_irq(keyinputdev.irqkeydesc[i].irqnum, &keyinputdev);
}
/* 释放input_dev */
input_unregister_device(keyinputdev.inputdev);
input_free_device(keyinputdev.inputdev);
}
module_init(keyinput_init);
module_exit(keyinput_exit);
MODULE_LICENSE("GPL");