字符设备驱动之Buttons-定时器(timer)

时间:2021-08-24 23:23:39

buttons.c

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/ioport.h>
#include <linux/pci.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/mach/irq.h>
#include <asm/arch/regs-gpio.h>
#include <linux/poll.h>

static int major = 0;
static struct class *cls;

/* gpecon 0x56000040 */
/* gpfcon 0x56000050 */
/* gpgcon 0x56000060 */
static volatile unsigned long *gpecon;
static volatile unsigned long *gpedat;

static volatile unsigned long *gpfcon;
static volatile unsigned long *gpfdat;

static volatile unsigned long *gpgcon;
static volatile unsigned long *gpgdat;

struct key_desc {
 int irq;
 int pin;
 char *name;
 char key_val;
 int irq_pin_val;
};


struct key_desc key_desc[] = {
 {IRQ_EINT0,  S3C2410_GPF0,  "K10", 1}, /* 松开: 1, 按下: 0x81 */
 {IRQ_EINT2,  S3C2410_GPF2,  "K7",  2}, /* 松开: 2, 按下: 0x82 */
 {IRQ_EINT11, S3C2410_GPG3,  "K4",  3}, /* 松开: 3, 按下: 0x83 */
 {IRQ_EINT19, S3C2410_GPG11, "K1",  4}, /* 松开: 4, 按下: 0x84 */
};
 
volatile char key = 0;

static wait_queue_head_t button_waitq;

#define BUF_LEN    10
static char key_buf[BUF_LEN];
static volatile int r = 0, w = 0;

struct fasync_struct *buttons_async;
static struct timer_list buttons_timer;

struct key_desc *cur_kd;

static int isEmpty(void)
{
 return (r == w);
}

static int isFull(void)
{
 return (r == ((w+1)%BUF_LEN));
}

static int putData(char val)
{
 if (isFull())
 {
  return -1;
 }
 else
 {
  key_buf[w] = val;
  w = (w+1)%BUF_LEN;
  return 0;
 }
}


static int getData(char *p)
{
 if (isEmpty())
 {
  return -1;
 }
 else
 {
  *p = key_buf[r];
  r = (r+1)%BUF_LEN;
  return 0;
 }
}


static irqreturn_t buttons_irq(int irq, void *dev_id)
{
 cur_kd = (struct key_desc *)dev_id;
 cur_kd->irq_pin_val = s3c2410_gpio_getpin(cur_kd->pin);

 mod_timer(&buttons_timer, jiffies+5);/*重置定时器*/
  
 return IRQ_HANDLED; 
}


static void buttons_timer_function(unsigned long data)
{
 /* 确定按键: 哪个按键,按下还是松开 */
 // for (i = 0; i < 10000; i++);  /* 浪费CPU */

 /* 启动一个定时器:
  * 两要素:
  * 1. 时间
  * 2. 处理函数
  */
 char key;
 int up;

 if (!cur_kd)
 {
  return;
 }
 
 up = s3c2410_gpio_getpin(cur_kd->pin); // gpfdat, gpgdat

 if (up != cur_kd->irq_pin_val)
 {
  return;
 }
 
 if (up)
 {
  key = cur_kd->key_val;
 }
 else
 {
  key = cur_kd->key_val | 0x80;
 }

 // printk("key = 0x%x\n", key);
 putData(key);

 /* 唤醒应用程序 */
 wake_up_interruptible(&button_waitq);
 
 kill_fasync(&buttons_async, SIGIO, POLL_IN);
 
 //printk("buttons_irq current %s , pid = %d \n", current->comm, current->pid);

}


int buttons_open(struct inode *inode, struct file *file)
{
 int i;
 
 /* 注册中断 */ 
 for (i = 0; i < 4; i++)
 {
  request_irq(key_desc[i].irq, buttons_irq,
              IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
              key_desc[i].name, &key_desc[i]);
 }


 /* 设置GPIO为中断引脚
  * 设置触发方式
  * 使能中断
  */

 /* 设置KSCAN0(GPE11)为输出引脚,输出0 */
 *gpecon &= ~(0x3 << 22);
 *gpecon |= (1 << 22);
 *gpedat &= ~(1<<11);
 
 return 0;
}

ssize_t buttons_read(struct file *file, char __user *buf, size_t size, loff_t *offset)
{
 /* 如果没有按键发生, 休眠 */
 /* key 等于 0, 才会休眠
  * key 非0, 不会休眠
  */
 // command
 //printk("current %s , pid = %d before sleep\n", current->comm, current->pid);
 char key;

 if (isEmpty() && (file->f_flags & O_NONBLOCK))
  return -EAGAIN;
 
 wait_event_interruptible(button_waitq, !isEmpty());
 
 //printk("current %s , pid = %d after sleep\n", current->comm, current->pid);

 /* 被唤醒后, 把按键值返回给用户程序 */
 getData(&key);
 copy_to_user(buf, &key, 1);

 /* 发生了中断, key=xxx */
 
 //key = 0;
 
 return 1;
}

int buttons_close(struct inode *inode, struct file *file)
{
 int i;
 for (i = 0; i < 4; i++)
 {
  free_irq(key_desc[i].irq, &key_desc[i]);
 }
 return 0;
}

static unsigned int buttons_poll(struct file *file, struct poll_table_struct *wait)
{
 static int cnt = 0;
 printk("buttons_poll cnt = %d\n", cnt++);
 poll_wait(file, &button_waitq, wait);  /* 不会休眠, 只是挂入队列 */
 return isEmpty()? 0 : POLLIN | POLLRDNORM;
}

static int buttons_fasync(int fd, struct file *filp, int on)
{
 int retval;

 retval = fasync_helper(fd, filp, on, &buttons_async);
 if (retval < 0)
  return retval;
 return 0;
}

static const struct file_operations buttons_fops = {
 .owner  = THIS_MODULE,
 .read  = buttons_read,
 .open  = buttons_open,  /* 设置引脚,申请资源 */
 .release = buttons_close,
 .poll    = buttons_poll,
 .fasync  = buttons_fasync,
};

int buttons_init(void)
{
 int i;
 
 major = register_chrdev(0, "buttons", &buttons_fops);

 /* sysfs  ==> 挂接到/sys */
 cls = class_create(THIS_MODULE, "buttons_class");
 class_device_create(cls, NULL, MKDEV(major, 0), NULL, "buttons");

 // mdev会根据/sys下的这些内容创建/dev/buttons

 gpecon = ioremap(0x56000040, 4096);
 gpedat = gpecon + 1;

 gpfcon = gpecon + 4;
 gpfdat = gpfcon + 1;

 gpgcon = gpecon + 8;
 gpgdat = gpgcon + 1;

 init_waitqueue_head(&button_waitq);

 init_timer(&buttons_timer);
 buttons_timer.function = buttons_timer_function;
 buttons_timer.expires = 0;

 add_timer(&buttons_timer);
 
 return 0;
}

void buttons_exit(void)

 unregister_chrdev(major, "buttons");

 class_device_destroy(cls, MKDEV(major, 0));
 class_destroy(cls);

 iounmap(gpecon); 

 del_timer(&buttons_timer);
}

module_init(buttons_init);
module_exit(buttons_exit);

MODULE_LICENSE("GPL");