Asynchronous notification, interrupt example (am335x)

Driver:

#include <linux/kernel.h>  #include <linux/module.h>  #include <linux/cdev.h>  #include <linux/fs.h>  #include <linux/device.h>  #include <linux/syscalls.h>#include <linux/interrupt.h> #include <linux/gpio.h>#include <linux/of_gpio.h>#include <linux/of_platform.h>#include <linux/uaccess.h>  #include <linux/string.h> #include <mach/gpio.h>#include <mach/irqs.h>#define GPIO_TO_PIN(bank, gpio) (32 * (bank) + (gpio))struct fpga_key_dev  {      struct cdev cdev;      dev_t devno;      char test[20];    struct class *fpga_key_class; struct fasync_struct *async_queue;int message_cdev_open;};  struct fpga_key_dev fpga_key_dev;  irqreturn_t irq_handler(int irqno, void *dev_id){struct fpga_key_dev *dev = &fpga_key_dev;static int count = 0;printk("fpga key down = %d\n", count);if (dev->async_queue)kill_fasync(&dev->async_queue, SIGIO, POLL_IN); return IRQ_HANDLED;}static int fpga_key_open(struct inode *node, struct file *fd)  {  struct fpga_key_dev *dev;printk("fpga_key_open()++\n");  printk("node->i_cdev = %x\n", (unsigned int)node->i_cdev);dev = container_of(node->i_cdev, struct fpga_key_dev, cdev);printk("dev->cdev = %x\n", (unsigned int)&dev->cdev);printk("dev = %x\n", (unsigned int)dev);if (!dev->message_cdev_open) {dev->message_cdev_open = 1;fd->private_data = dev;}else{return -EFAULT;}printk("test[20] = %s\n",dev->test);    printk("fpga_key_open()--\n");        return 0;  }     static ssize_t fpga_key_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)  {      char temp_buffer [20];      int print_size = 0;            printk("fpga_key_wirte()++\n");      if(len > 20)          print_size = 20;      else          print_size = len;      printk("print_size = %d; len = %d\n", print_size, len);      if(copy_from_user(temp_buffer, buf, print_size))          return -EFAULT;        printk("writing data:%s", temp_buffer);            printk("fpga_key_wirte()--\n");        return print_size;  }  static ssize_t fpga_key_read(struct file *fd, char __user *buf, size_t len, loff_t *ptr)  {        char *temp_buffer = "Hello fpga_key_read !\n";        int print_size = 0;              printk("fpga_key_read()++\n");            if(len > strnlen(temp_buffer,20))          print_size = strnlen(temp_buffer,20);      else          print_size = len;      printk("print_size = %d; len = %d\n", print_size, len);      if(copy_to_user(buf, temp_buffer, print_size))          return -EFAULT;      printk("%s", temp_buffer);      printk("fpga_key_read()--\n");        return print_size;  }  static int fpga_key_fasync(int fd, struct file *filp, int mode){struct fpga_key_dev*dev = filp->private_data;printk("fpga_key_fasync()++\n");fasync_helper(fd, filp, mode, &dev->async_queue); printk("fpga_key_fasync()--\n");return 0;}static int fpga_key_release(struct inode *node, struct file *fd)  {  struct fpga_key_dev *dev = fd->private_data;printk("fpga_key_release()++\n"); dev->message_cdev_open = 0;fpga_key_fasync(-1, fd, 0);    printk("fpga_key_release()--\n");      return 0;  } struct file_operations meassage_operatons =  {      .owner = THIS_MODULE,      .open = fpga_key_open,      .write = fpga_key_write,    .read = fpga_key_read,     .fasync = fpga_key_fasync,    .release = fpga_key_release,  };    static int __init fpga_key_init(void)  {      struct fpga_key_dev * dev;  char * temp_char = "hello world\n";int ret = 0;int irq = 0;      printk("fpga_key_to_app_init(void)++\n");        dev = &fpga_key_dev;  strcpy(dev->test, temp_char);;    alloc_chrdev_region(&dev->devno, 0, 1, "fpga_key_to_app");      cdev_init(&dev->cdev, &meassage_operatons);      cdev_add(&dev->cdev, dev->devno, 1);      dev->fpga_key_class = class_create(THIS_MODULE, "fpga_key_class");      if(IS_ERR(dev->fpga_key_class)) {           printk("Err: failed in creating class./n");           goto fail1;        }      device_create(dev->fpga_key_class, NULL, dev->devno, NULL, "fpga_key");  //init irqret = gpio_request(GPIO_TO_PIN(1, 27), "fpga_key_inter");if(ret){printk("gpio_request() failed !\n");goto fail1;}ret = gpio_direction_input(GPIO_TO_PIN(1, 27));if(ret){printk("gpio_direction_input() failed !\n");goto fail2;}irq = gpio_to_irq(GPIO_TO_PIN(1, 27));if(irq < 0){printk("gpio_to_irq() failed !\n");ret = irq;goto fail2;}printk("irq = %d\n", irq);ret = request_irq(irq, irq_handler, IRQF_TRIGGER_FALLING | IRQF_SHARED, "fpga_key_inter", &dev->devno); if(ret){printk("request_irq() failed ! %d\n", ret);goto fail2;}    printk("fpga_key_to_app_init(void)--\n");          return 0;  fail2:gpio_free(GPIO_TO_PIN(1, 27));fail1:    device_destroy(dev->fpga_key_class, dev->devno);      class_destroy(dev->fpga_key_class);       cdev_del(&dev->cdev);      unregister_chrdev_region(dev->devno, 1);  return ret;}  static void __exit fpga_key_exit(void)  {      struct fpga_key_dev *dev = &fpga_key_dev;  int irq = 0;      printk("fpga_key_to_app_exit(void)++\n"); irq = gpio_to_irq(GPIO_TO_PIN(1, 27));printk("irq = %d\n", irq);free_irq(irq, &dev->devno); gpio_free(GPIO_TO_PIN(1, 27));    device_destroy(dev->fpga_key_class, dev->devno);      class_destroy(dev->fpga_key_class);       cdev_del(&dev->cdev);      unregister_chrdev_region(dev->devno, 1);             printk("fpga_key_to_app_exit(void)--\n");  }  module_init(fpga_key_init);  module_exit(fpga_key_exit);    MODULE_LICENSE("GPL");  MODULE_AUTHOR("Driver Monkey");  MODULE_DESCRIPTION("Test fpga_key to App");  

Test procedure:

#include<stdio.h>  #include<sys/types.h>  #include<sys/stat.h>  #include<fcntl.h>  #include<sys/select.h>  #include<unistd.h>  #include<signal.h>  #include<string.h>    unsigned int flag = 0;    void sig_handler(int sig)  {    printf("%s\n",__FUNCTION__);    flag++;    printf("flag = %d\n", flag);}  int main(void)  {      char r_buf[20];      char *w_buf = "hello write!\n";      int r_count = 0;      int fd;      int f_flags;      flag++;      fd=open("/dev/fpga_key",O_RDWR);      if(fd<0)      {          perror("open");          return-1;      }      signal(SIGIO, sig_handler);     fcntl(fd, F_SETOWN, getpid());    f_flags = fcntl(fd, F_GETFL);    fcntl(fd, F_SETFL, FASYNC | f_flags);     while(1)    {    printf("waiting \n");     sleep(2);    if(flag > 3)    break;    }           close(fd);        return 0;  }