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linux gpio喂狗驱动
0. linux版本
Linux version 5.4.31- 1
1.设备树
usr_wtd { compatible = "user-watchdog"; status = "okay"; gpio = <&gpiof 3 GPIO_ACTIVE_HIGH>; pluse-width = <100>; /* 1ms */ pluse-inverse = <1>; pluse-count = <3>; timeout-sec = <5>; };- 1
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2. 驱动 drivers/watchdog/usr_wtd.c
#include#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* #include 第一类延时函数原型是:（忙等） void ndelay(unsigned long nsecs); void udelay(unsigned long usecs); void mdelay(unsigned long msecs); 说明：内核函数 ndelay, udelay, 以及 mdelay 对于短延时好用, 分别延后执行指定的纳秒数, 微秒数或者毫秒数. 它们涉及到的延时常常是最多几个毫秒。 第二类延时函数原型是:（使进程进入休眠） void msleep(unsigned int millisecs); unsigned long msleep_interruptible(unsigned int millisecs); void ssleep(unsigned int seconds) */ #define WATCHDOG_TAG "[wtd_tag]" #define WATCHDOG_MAJOR 0 #define WATCHDOG_NAME "usr_wdt" //设备节点 struct wtd_device_t { int gpio; int pluse_width; int pluse_count; int timeout_sec; int pluse_inverse; int status; struct timer_list timer; struct class *wtd_class; int major; }; static struct wtd_device_t watchdog_dev; static void feed_dog(struct wtd_device_t *dev) { int i = 0; //printk(WATCHDOG_TAG"feed dog,count:%d,gpio:%d,width:%d\n",dev->pluse_count,dev->gpio,dev->pluse_width); for(i=0;i<dev->pluse_count;i++){ gpio_direction_output(dev->gpio,dev->pluse_inverse); mdelay(dev->pluse_width); gpio_direction_output(dev->gpio,!dev->pluse_inverse); mdelay(dev->pluse_width); } gpio_direction_output(dev->gpio,dev->pluse_inverse); } static void timer_function(struct timer_list *t) { struct wtd_device_t *wtd = from_timer(wtd, t, timer); feed_dog(wtd); mod_timer(&wtd->timer, jiffies + wtd->timeout_sec * HZ); } static int watchdog_pin_config(int gpio) { int ret = 0; gpio_free(gpio); ret = gpio_request(gpio,"watchdog_pin"); if(ret){ printk(WATCHDOG_TAG"%s::request gpio[%d] failed\n",__FUNCTION__,gpio); return -1; }else{ printk(WATCHDOG_TAG"%s::request gpio[%d] successfully\n",__FUNCTION__,gpio); } return 0; } static int init_wtd_timer(struct wtd_device_t *dev) { timer_setup(&dev->timer,timer_function,0); mod_timer(&dev->timer, jiffies + dev->timeout_sec * HZ); return 0 ; } static int watchdog_open(struct inode* inode,struct file* file) { return 0; } static int watchdog_release(struct inode* inode ,struct file* file) { return 0; } #if 0 static int watchdog_ioctl(struct inode* inode, struct file* file,unsigned int cmd, unsigned long arg) { return 0; } #endif static int watchdog_read(struct file *file, char __user *buf, size_t count, loff_t *offset) { return 0; } static int watchdog_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) { return 0; } static struct file_operations watchdog_fops = { .owner = THIS_MODULE, .open = watchdog_open, .release = watchdog_release, .write = watchdog_write, .read = watchdog_read, }; static int user_wtd_probe(struct platform_device * pdev) { struct device_node * node = pdev->dev.of_node; int ret; int num = 0; int gpio = 0; enum of_gpio_flags flags; struct wtd_device_t *dev = &watchdog_dev; if(!node) return -ENODEV; dev->major = register_chrdev(WATCHDOG_MAJOR,WATCHDOG_NAME,&watchdog_fops); if(dev->major <0){ printk(WATCHDOG_TAG" register failed \n"); return dev->major; } dev->wtd_class = class_create(THIS_MODULE,WATCHDOG_NAME); if(IS_ERR(dev->wtd_class)){ printk(WATCHDOG_TAG " register class failed \n"); return -1; } device_create(dev->wtd_class,NULL,MKDEV(dev->major,0),NULL,WATCHDOG_NAME); /* usr_wtd { compatible = "user-watchdog"; status = "okay"; gpio = <&gpioh 15 GPIO_ACTIVE_HIGH>; pluse-inverse = <1>; pluse-width = <1>; pluse-count = <2>; timeout-sec = <32>; }; */ ret = of_property_read_u32(node, "pluse-inverse", &num); if (ret) { pr_err(WATCHDOG_TAG"pluse-inverse no found !!!\n"); goto INIT_ERR_FREE; } printk("pluse-inverse:%d\n",num); dev->pluse_inverse = num; ret = of_property_read_u32(node, "pluse-width", &num); if (ret || !num) { pr_err(WATCHDOG_TAG"pluse-width no found !!!\n"); goto INIT_ERR_FREE; } printk("pluse-width:%d\n",num); dev->pluse_width = num; ret = of_property_read_u32(node, "pluse-count", &num); if (ret || !num) { pr_err(WATCHDOG_TAG"pluse-count no found !!!\n"); goto INIT_ERR_FREE; } printk("pluse-count:%d\n",num); dev->pluse_count = num; ret = of_property_read_u32(node, "timeout-sec", &num); if (ret || !num) { pr_err(WATCHDOG_TAG"timeout-sec no found !!!\n"); goto INIT_ERR_FREE; } printk("timeout-sec:%d\n",num); dev->timeout_sec = num; gpio = of_get_named_gpio_flags(node, "gpio", 0,&flags); dev->gpio = gpio; ret = watchdog_pin_config(gpio); if (ret) { goto INIT_ERR_FREE; } init_wtd_timer(dev); dev_set_drvdata(&pdev->dev, dev); pr_info("init watchdog dev finish\n"); return 0; INIT_ERR_FREE: pr_err("init watchdog dev err\n"); return -1; } static int user_wtd_remove(struct platform_device *pdev) { struct wtd_device_t * dev = dev_get_drvdata(&pdev->dev); if(dev != NULL){ del_timer(&dev->timer); unregister_chrdev(dev->major,WATCHDOG_NAME); device_destroy(dev->wtd_class,MKDEV(dev->major ,0)); class_destroy(dev->wtd_class); } pr_info("exit user watchdog \n"); return 0; } #ifdef CONFIG_PM static int user_wtd_suspend(struct device *dev) { return 0; } static int user_wtd_resume(struct device *dev) { return 0; } #else #define user_wtd_suspend NULL #define user_wtd_resume NULL #endif static const struct dev_pm_ops user_wtd_pm_ops = { .suspend = user_wtd_suspend, .resume = user_wtd_resume, }; static struct of_device_id user_wtd_of_match[] = { { .compatible = "user-watchdog" }, {}, }; MODULE_DEVICE_TABLE(of, user_wtd_of_match); static struct platform_driver user_wtd_driver = { .driver = { .name = "user-wtd", .owner = THIS_MODULE, .pm = &user_wtd_pm_ops, .of_match_table = of_match_ptr(user_wtd_of_match), }, .probe = user_wtd_probe, .remove = user_wtd_remove, }; module_platform_driver(user_wtd_driver); MODULE_DESCRIPTION("user watchdog driver"); MODULE_AUTHOR("zhengweiqing, 1548889230@qq.com"); MODULE_LICENSE("GPL");- 1
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3. drivers/watchdog/Makefile
末尾增加：
obj-m += usr_wtd.o- 1
4. 编译
5. 使用
insmod usr_wtd.ko- 1
6. 现象
usr_wtd { compatible = "user-watchdog"; status = "okay"; gpio = <&gpiof 3 GPIO_ACTIVE_HIGH>; pluse-width = <100>; pluse-inverse = <1>; pluse-count = <3>; timeout-sec = <5>; };- 1
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timeout-sec：周期，单位秒
pluse-inverse：脉冲是否反向
pluse-count：脉冲个数
pluse-width：脉冲宽度，单位毫秒这里举例的是：每隔5秒有3个宽度为100毫秒的脉冲。
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- 原文地址：https://blog.csdn.net/weixin_43479963/article/details/126329382
