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饭店餐厅网站建设,网站 源码 php,东莞网站优化,简述网站设计流程默认打开文件时候是阻塞的 当设置打开方式为非阻塞时#xff0c;无数据时会返回。 当设置打开方式为阻塞时#xff0c;无数据的时候会等待1.设置打开方式为非阻塞 立即返回#xff0c;无法读出#xff0c;返回-1
2.设置为阻塞
核心在于驱动程序中的.read函数的支持 …默认打开文件时候是阻塞的 当设置打开方式为非阻塞时无数据时会返回。 当设置打开方式为阻塞时无数据的时候会等待1.设置打开方式为非阻塞 立即返回无法读出返回-1
2.设置为阻塞
核心在于驱动程序中的.read函数的支持
3.代码实现 应用程序 #include stdio.h #include sys/types.h #include sys/stat.h #include fcntl.h #include unistd.h #include poll.h #include signal.hstatic int fd;/* 信号处理函数 */ /*static void sig_func(int sig) {int val;int num;read(fd,val,4);num val 8;printf(get button: %d val %d\n, num, val - num (1 8)); }/int main(int argc, char** argv) {int val;int num;struct pollfd fds[1];int timeout_ms 5000;int ret;int flags;int i;/* 判断输入值是否合法 /if(argc ! 2){printf(Usage ./button_app /dev/devname\n);return -1;}fd open(argv[1], O_RDONLY);if (fd -1){printf(open err\n);}else{printf(open success\n);}/ 初始化文件监听描述符 *//fds[0].fd fd;fds[0].events POLLIN;//*绑定SIGIO和sig_func ///signal(SIGIO, sig_func);/ APP把自己的pid告诉驱动 ///fcntl(fd, F_SETOWN, getpid());/ APP把自己的pid告诉驱动程序 ///flags fcntl(fd,F_GETFL);/ 获得标志位 ///fcntl(fd, F_SETFL, flags | FASYNC);/ 使能异步通知 *///printf(设置了FASYNC\n);/while(1){printf(www.100ask.net \n);sleep(2);}//*while(1){ret poll(fds, 1, timeout_ms);if((ret 1) (fds[0].revents POLLIN)){read(fd, val, 4);num val 8;printf(get button: %d val %d\n, num, val - num (1 8));}else{printf(timeout\n);}}//* 设置打开方式为非阻塞 /fcntl(fd,F_SETFL,O_NONBLOCK);for (i 0; i 10; i){if (read(fd, val, 4) 4)printf(get button: 0x%x\n, val);elseprintf(get button: -1\n);}/ 设置打开方式为阻塞 */flags fcntl(fd,F_GETFL);fcntl(fd,F_SETFL,flags ~O_NONBLOCK);while(1){if (read(fd, val, 4) 4){num val 8;printf(get button: %d val %d\n, num, val - num (1 8));}elseprintf(get button: -1\n);}close(fd);return 0; } 驱动程序 #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; };/* 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) ((x1) % 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®;}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);return IRQ_HANDLED; }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 isnt 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);}}/ 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); 4.代码路径 /home/book/nfs_rootfs/CSDN/01_gpio_irq/06_read_key_irq_poll_fasync_block