【DragonBoard 410c试用体验】6.DB410c开发板基于GPIO模型实现蜂鸣器功能测试。

2016-9-8 14:57:42 3212 蜂鸣器

0 这个帖子主要理解如何自己实现一个简单驱动。自己使用是某宝买来的无源蜂鸣器，它内部不带震荡源所以直流信号无法令其鸣叫，必须用2K~5K的方波去驱动它。广泛应用于计算机、报警器、电子玩具、汽车电子设备、定时器等电子产品中作发声器件。驱动代码主要是参考论坛某人的大作，这个特意表示感谢。 #include #include #include #include #include #include #include #include #include #include #include #include #include #include "buzzer_drv.h" static int major; static int minor; struct cdev buzzer; / cdev 数据结构 / static dev_t devno; / 设备编号 / static struct class buzzer_class; #define DEVICE_NAME "buzzer" #define GPIO_BUZZER_PIN_NUM 12 //(232 + 12) /gpio 2_12 / static int buzzer_open(struct inode inode,struct file file ) { try_module_get(THIS_MODULE); gpio_direction_output(GPIO_BUZZER_PIN_NUM,1); return 0; } static int buzzer_release(struct inodeinode, struct file file ) { module_put(THIS_MODULE); gpio_direction_output(GPIO_BUZZER_PIN_NUM,1); return 0; } #if LINUX_VERSION_CODE >=KERNEL_VERSION(2,6,36) static int buzzer_ioctl(struct file filp,unsigned int cmd, unsigned long arg) #else static int buzzer_ioctl(struct inodeinode, struct file file, unsigned int cmd, unsigned long arg) #endif { printk(KERN_INFO "buzzer_ioctl cmd=%d BUZZER_IOC_MAGIC=%d BUZZER_IOCTL_MAXNR=%dn", cmd, BUZZER_IOC_MAGIC, BUZZER_IOCTL_MAXNR); #if 0 if(cmd != BUZZER_IOC_MAGIC) { return -ENOTTY; } if(cmd > BUZZER_IOCTL_MAXNR) { return -ENOTTY; } #endif printk(KERN_INFO "buzzer_ioctl cmd=%d BUZZER_ON=%d BUZZER_OFF=%dn", cmd, BUZZER_ON, BUZZER_OFF); switch(cmd){ case BUZZER_ON: gpio_set_value(GPIO_BUZZER_PIN_NUM,1); break; case BUZZER_OFF: gpio_set_value(GPIO_BUZZER_PIN_NUM,0); break; default: break; } return 0; } struct file_operations buzzer_fops = { .owner= THIS_MODULE, .open= buzzer_open, .release= buzzer_release, #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36) .unlocked_ioctl = buzzer_ioctl, #else .ioctl= buzzer_ioctl, #endif }; static int __init buzzer_init(void) { int ret; gpio_free(GPIO_BUZZER_PIN_NUM); if(gpio_request(GPIO_BUZZER_PIN_NUM, "buzzer_bee")) { printk("request%s gpio faile n", "led_bee"); return-1; } ret= alloc_chrdev_region(&devno, minor, 1, "buzzer"); /* 从系统获取主设备号 / major= MAJOR(devno); if(ret < 0) { printk(KERN_ERR"cannot get major %d n", major); return-1; } buzzer= cdev_alloc(); / 分配 buzzer 结构 / if(buzzer != NULL) { cdev_init(buzzer,&buzzer_fops); / 初始化 buzzer 结构 / buzzer->owner= THIS_MODULE; if(cdev_add(buzzer, devno, 1) != 0) { / 增加 buzzer 到系统中 / printk(KERN_ERR"add cdev error!n"); goto error; } }else { printk(KERN_ERR"cdev_alloc error!n"); return-1; } buzzer_class = class_create(THIS_MODULE, "buzzer_class"); if(IS_ERR(buzzer_class)) { printk(KERN_INFO"create class errorn"); return-1; } device_create(buzzer_class,NULL, devno, NULL, "buzzer"); return 0; error: unregister_chrdev_region(devno,1); / 释放已经获得的设备号 / return ret; } static void __exit buzzer_exit(void) { cdev_del(buzzer);/ 移除字符设备 / unregister_chrdev_region(devno,1); / 释放设备号 / device_destroy(buzzer_class,devno); class_destroy(buzzer_class); } module_init(buzzer_init); module_exit(buzzer_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("zxl_zxl"); 代码几乎没有做任何变动，除非有必要，比如适合自己硬件的GPIO定义GPIO_BUZZER_PIN_NUM。还有一些相关头文件定义。下面是测试程序代码。 #include #include #include #include #include #include #include "buzzer_drv.h" #define DEV_NAME "/dev/buzzer" int main(int argc, char argv[]) { int i; int fd = 0; fd = open (DEV_NAME, O_RDONLY); if(fd < 0) { perror("Open"DEV_NAME" Failed!n"); exit(1); } while(1){ printf("BUZZER_ON then sleep 1 n"); ioctl(fd,BUZZER_ON); sleep(1); ioctl(fd,BUZZER_OFF); printf("BUZZER_ON then BUZZER_OFF 1 n"); sleep(1); } close(fd); return 0; } 编译命令：make ARCH=ARM64 CROSS_COMPILE=${DB410C_CROSSTOOL} insmod buzzer_drv.ko加载驱动 ./buzzer_test开始测试，可以听到蜂鸣器根据代码反复响，停。蜂鸣器接入开发板pin24，gpio为12. 0
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