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linux驅動開發--中斷：tasklet實現中斷底半部
1、在Linux 中實現中斷底半部的機製主要是：
tasklet、工作隊列、軟中斷
2、tasklet
定義在<linux/interrupt.h>中
tasklet定義
DECLARE_TASKLET(taskletname, tasklet_func, data);
taskletname:待定義的tasklet名字
tasklet_func:tasklet處理函數
data:待傳入tasklet處理函數的參數
tasklet處理函數
void tasklet_func(unsigned long data);
tasklet調用
在中斷處理函數中弟阿勇tasklet_schedule()函數
void tasklet_schedule(struct tasklet_struct *taskletname);
3、軟中斷
軟中斷使用軟件方式模擬硬件中斷，目的是實現異步執行。
tasklet即基於軟中斷實現。
軟終端和tasklet仍然運行於中斷上下文，工作隊列運行於進程上下文。
/**
*Copyright (c) 2013.TianYuan
*All rights reserved.
*
*文件名稱: irq.c
*文件標識: tasklet實現，登記底半部
*make menuconfig--- device drivers
*input keyboards ---s3c gpio keypad supports
#cat /proc/interrupts : 32(中斷號) :intertupt_demo
*
*當前版本：1.0
*作者：wuyq
*
*取代版本：xxx
*原作者：xxx
*完成日期：2014-03-05
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/gpio.h>
#include <plat/gpio-cfg.h>
#include <linux/spinlock_types.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/interrupt.h>
MODULE_LICENSE("GPL");
#define CDD_MAJOR 200//cat /proc/devices找一個尚未使用的
#define CDD_MINOR 0
#define CDD_COUNT 10
dev_t dev = 0;
u32 cdd_major = 0;
u32 cdd_minor = 0;
struct class *dev_class = NULL;
#define BUF_SIZE 100
struct cdd_cdev{
struct cdev cdev;
struct device *dev_device;
u8 led;
char kbuf[BUF_SIZE];
u32 data_len;//記錄緩衝區中已經寫入數據的長度
//定義等待隊列頭
wait_queue_head_t wqh;
};
struct cdd_cdev *cdd_cdevp = NULL;
unsigned long led_gpio_table[2] = {
S5PV210_GPC1(3),//數字
S5PV210_GPC1(4),
};
int cdd_open(struct inode* inode, struct file *filp)
{
struct cdd_cdev *pcdevp = NULL;
printk("enter cdd_open!\n");
pcdevp = container_of(inode->i_cdev, struct cdd_cdev, cdev);
printk("led = %d\n", pcdevp->led);
/*獲取信號量*/
//down獲取信號量不成功，會導致進程睡眠（第3個進程的時候）
//down(&pcdevp->sem_open);
if(down_interruptible(&pcdevp->sem_open)<0){
return -1;
}
filp->private_data = pcdevp;
//申請gpio管腳
gpio_request(led_gpio_table[0], "GPC1_3");
gpio_request(led_gpio_table[1], "GPC1_4");
return 0;
}
int cdd_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
{
int ret = 0;
u32 pos = *offset;
u32 cnt = count;
struct cdd_cdev *cdevp = filp->private_data;
#if 0
//定義並初始化一個等待隊列
DECLARE_WAITQUEUE(wq, current);
//將等待隊列添加到wqh指向的鏈表
add_wait_queue(&pcdevp->wqh, &wq);
//判斷設備有沒有數據供用戶空間讀,假設led不為0，表示有數據供用戶空間讀取
if(pcdevp->led == 0){
printk("no data for reading! sleep...\n");
//設置當前線程為睡眠狀態
set_current_state(TASK_INTERRUPTIBLE);
schedule();//內核調度cpu的算法
printk("have data for reading!\n");
}
//從指定的鏈表中刪除等待隊列
remove_wait_queue(&pcdevp->wqh, &wq);
#endif
wait_event_interruptible(pcdevp->wqh, pcdevp->led != 0);
//printk("enter cdd_read!\n");
if(cnt > (cdevp->data_len-pos) ){
cnt = cdevp->data_len - pos;
}
ret = copy_to_user(buf, cdevp->kbuf+pos, cnt);
//printk("kernel kbuf content:%s\n", cdevp->kbuf);
*offset += cnt;
pcdevp->led = 0;
return ret;
}
int cdd_write(struct file *filp, const char __user *buf, size_t count, loff_t *offset)
{
int ret = 0;
struct cdd_cdev *cdevp = filp->private_data;
u32 pos = *offset;
u32 cnt = count;
//printk("enter cdd_write!\n");
if(cnt > (BUF_SIZE - pos) ){
cnt = BUF_SIZE - pos;
}
ret = copy_from_user(cdevp->kbuf+pos, buf, cnt);
*offset += cnt;
if(*offset > cdevp->data_len){
cdevp->data_len = *offset;
}
pcdevp->led = 1;
//喚醒等待隊列頭中的一個等待隊列
wake_up_interruptible(&pcdevp->wqh);
return ret;
}
int cdd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long data)
{
//printk("enter cdd_ioctl!\n");
switch(cmd){
case 1://點亮燈
//設置管腳為輸出功能
//參數：1.要設置的管腳編號2.默認的輸出值 0低電平1高電平
gpio_direction_output(led_gpio_table[data], 0);
//禁止內部上拉
s3c_gpio_setpull(led_gpio_table[data], SEC_GPIO_PULL_NONE);
//設置輸出值
gpio_set_value(led_gpio_table[data], 1);
break;
case 0://熄滅燈
//設置管腳為輸出功能
//參數：1.要設置的管腳編號2.默認的輸出值 0低電平1高電平
gpio_direction_output(led_gpio_table[data], 0);
//禁止內部上拉
s3c_gpio_setpull(led_gpio_table[data], SEC_GPIO_PULL_NONE);
//設置輸出值
gpio_set_value(led_gpio_table[data], 0);
break;
default:
return -EINVAL;
}
return 0;
}
int cdd_release(struct inode *inode, struct file *filp)
{
struct cdd_cdev *pcdevp = filp->private_data;
printk("enter cdd_release!\n");
gpio_free(led_gpio_table[0]);
gpio_free(led_gpio_table[1]);
up(&pcdevp->sem_open);
return 0;
}
loff_t cdd_llseek(struct file *filp, loff_t offset, int whence)
{
struct cdd_cdev *pcdevp = filp->private_data;
loff_t newpos = 0;
switch(whence){
case SEEK_SET:
newpos = offset;
break;
case SEEK_CUR:
newpos = filp->f_pos + offset;
break;
case SEEK_END:
newpos = pcdevp->data_len + offset;
break;
default:
return -EINVAL;//無效的參數
}
if( newpos<0 || newpos>= BUF_SIZE ){
return -EINVAL;
}
filp->f_pos = newpos;
return newpos;
}
unsigned int cdd_poll(struct file *filp, struct poll_table_struct *wait)
{
unsigned int mask = 0;
struct cdd_cdev pcdevp = filp->private_data;
printk("enter cdd_poll!\n");
poll_wait(filp, &pcdep->wqh, wait);
//led不為0即可讀
if(pcdevp->led){
mask = POLLIN | POLLRDNORM;
}
return mask;
}
struct file_operations cdd_fops = {
.owner = THIS_MODULE,
.open = cdd_open,
.read = cdd_read,
.write = cdd_write,
.ioctl = cdd_ioctl,
.release = cdd_release,
.llseek = cdd_llseek,
.poll = cdd_poll,
};
void cdd_func(unsigned long data)
{
int i = 10000000;
printk("enter cdd_func!\n");
while(i--);//耗時
printk("exit cdd_func!\n");
}
//定義tasklet
DECLARE_TASKLET(cdd_tasklet, cdd_func, 0);
irqreturn_t cdd_isr(int irq, void *dev_id)
{
printk("occur up key press or release!\n");
//登記底半部
tasklet_schedule(&cdd_tasklet); `
printk("exit cdd_isr!\n");
return IRQ_HANDLED;
}
int __init cdd_init(void)
{
int ret = 0;
int i = 0;
if(cdd_major){
dev = MKDEV(CDD_MAJOR, CDD_MINOR);//生成設備號
//注冊設備號;1、要注冊的起始設備號2、連續注冊的設備號個數3、名字
ret = register_chrdev_region(dev, CDD_COUNT, "cdd_demo");
}else{
// 動態分配設備號
ret = alloc_chrdev_region(&dev, cdd_minor, CDD_COUNT, "cdd_demo02");
}
if(ret < 0){
printk("register_chrdev_region failed!\n");
goto failure_register_chrdev;
}
//獲取主設備號
cdd_major = MAJOR(dev);
printk("cdd_major = %d\n", cdd_major);
cdd_cdevp = kzalloc(sizeof(struct cdd_cdev)*CDD_COUNT, GFP_KERNEL);
if(IS_ERR(cdd_cdevp)){
printk("kzalloc failed!\n");
goto failure_kzalloc;
}
/*創建設備類*/
dev_class = class_create(THIS_MODULE, "cdd_class");
if(IS_ERR(dev_class)){
printk("class_create failed!\n");
goto failure_dev_class;
}
for(i=0; i<CDD_COUNT; i++){
/*初始化cdev*/
cdev_init(&(cdd_cdevp[i].cdev), &cdd_fops);
/*添加cdev到內核*/
cdev_add(&(cdd_cdevp[i].cdev), dev+i, 1);
/* “/dev/xxx” */
device_create(dev_class, NULL, dev+i, NULL, "cdd%d", i);
cdd_cdevp[i].led = i;
//初始化等待隊列頭
init_waitqueue_head(&cdd_cdevp[i].wqh);
}
//注冊中斷
request_irq(IRQ_EINT0, cdd_isr, IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING, "interrupt_demo", NULL);
return 0;
failure_dev_class:
kfree(cdd_cdevp);
failure_kzalloc:
unregister_chrdev_region(dev, CDD_COUNT);
failure_register_chrdev:
return ret;
}
void __exit cdd_exit(void)
{
/*逆序消除*/
int i = 0;
for(; i < CDD_COUNT; i++){
device_destroy(dev_class, dev+i);
cdev_del(&(cdd_cdevp[i].cdev));
//cdev_del(&((cdd_cdevp+i)->cdev));
}
class_destroy(dev_class);
kfree(cdd_cdevp);
unregister_chrdev_region(dev, CDD_COUNT);
free_irq(IRQ_EINT0, NULL);
}
module_init(cdd_init);
module_exit(cdd_exit);
最後更新：2017-04-03 12:55:24