字元裝置驅動(五)按鍵優化休眠
阿新 • • 發佈：2018-11-23
目錄
title: 字元裝置驅動(五)按鍵優化
tags: linux
date: 2018-11-23 17:56:57
toc: true
---
字元裝置驅動(五)按鍵優化
按鍵值讀取
Linux內部有系統函式s3c2410_gpio_getpin能夠讀取GPIO的值
unsigned int s3c2410_gpio_getpin(unsigned int pin) { void __iomem *base = S3C24XX_GPIO_BASE(pin); unsigned long offs = S3C2410_GPIO_OFFSET(pin); return __raw_readl(base + 0x04) & (1<< offs); }
在中斷處理函式中有個引數是dev_id,這個是由request_irq初始化的,處理函式可以用這個結構體傳遞引數
static irqreturn_t buttons_irq(int irq, void *dev_id) 也就是說一箇中斷綁定了一個dev_id,可用作傳遞引數,解除安裝中斷函式
request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]); free_irq(IRQ_EINT0, &pins_desc[0]); static irqreturn_t buttons_irq(int irq, void *dev_id) { struct pin_desc * pindesc = (struct pin_desc *)dev_id; unsigned int pinval; pinval = s3c2410_gpio_getpin(pindesc->pin); //這裡就讀取到了 }
休眠讀取
程式設計
程式設計目的:App去讀取按鍵值,如果有按鍵中斷觸發(鍵值有改變)則列印,否則休眠.
read(key)
if change
printf
else
sleep也就是說App函式依然不變,但是需要修改驅動的讀取函式,驅動的讀取函式中有休眠的動作
// app.c #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <unistd.h> int main(int argc, char **argv) { int fd; unsigned char key_val; fd = open("/dev/xyz0", O_RDWR); if (fd < 0) { printf("can't open!\n"); } while (1) { read(fd, &key_val, 1); printf("key_val = 0x%x\n", key_val); } return 0; }
驅動程式中需要設計休眠,中斷髮生來喚醒首先定義一個等待佇列,下述是一個巨集
//生成一個等待佇列頭wait_queue_head_t,名字為name
DECLARE_WAIT_QUEUE_HEAD(name)
// 定義一個名為`button_waitq`的佇列
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);休眠函式如下,condition=0才休眠,定義在include/linux/wait.h
#define wait_event_interruptible(wq, condition) \
({ \
int __ret = 0; \
if (!(condition)) \
__wait_event_interruptible(wq, condition, __ret); \
__ret; \
})喚醒也是一個巨集,引數是等待佇列,放置在中斷函式處理中,定義在include/linux/wait.h
wake_up_interruptible(&button_waitq); /* 喚醒休眠的程序 */
完整程式碼如下
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>
//#include <linux/interrupt.h>
volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;
volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;
static struct class *drv_class;
static struct class_device *drv_class_dev;
// 定義一個名為`button_waitq`的佇列
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
// flag=1 means irq happened and need to update
int flag=0;
struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
/* 鍵值: 按下時, 0x01, 0x02, 0x03, 0x04 */
/* 鍵值: 鬆開時, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;
struct pin_desc pins_desc[4] = {
{S3C2410_GPF0, 0x01},
{S3C2410_GPF2, 0x02},
{S3C2410_GPG3, 0x03},
{S3C2410_GPG11, 0x04},
};
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
printk("irq%d\r\n",irq);
struct pin_desc * pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
pinval = s3c2410_gpio_getpin(pindesc->pin);
if (pinval)
{
/* 鬆開 */
key_val = 0x80 | pindesc->key_val;
}
else
{
/* 按下 */
key_val = pindesc->key_val;
}
wake_up_interruptible(&button_waitq); /* 喚醒休眠的程序 */
flag=1;
return IRQ_RETVAL(IRQ_HANDLED);
}
static int drv_open(struct inode *inode, struct file *file)
{
/* 配置GPF0,2為輸入引腳 */
/* 配置GPG3,11為輸入引腳 */
request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);
request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);
request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);
request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]);
return 0;
}
int drv_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0, &pins_desc[0]);
free_irq(IRQ_EINT2, &pins_desc[1]);
free_irq(IRQ_EINT11,&pins_desc[2]);
free_irq(IRQ_EINT19,&pins_desc[3]);
return 0;
}
static ssize_t drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
//int minor = MINOR(file->f_dentry->d_inode->i_rdev);
//printk("drv_write=%d\n",minor);
return 0;
}
static ssize_t drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
if (size != 1)
return -EINVAL;
/* 如果沒有按鍵動作, 休眠 */
wait_event_interruptible(button_waitq, flag);
/* 如果有按鍵動作, 返回鍵值 */
copy_to_user(buf, &key_val, 1);
flag = 0;
return 1;
}
static struct file_operations drv_fops = {
.owner = THIS_MODULE, /* 這是一個巨集，推向編譯模組時自動建立的__this_module變數 */
.open = drv_open,
.write = drv_write,
.read = drv_read,
.release = drv_close,
};
static int major;
static int drv_init(void)
{
int minor=0;
major=register_chrdev(0, "drv", &drv_fops); // 註冊, 告訴核心
drv_class = class_create(THIS_MODULE, "drv");
drv_class_dev = class_device_create(drv_class, NULL, MKDEV(major, 0), NULL, "xyz%d", minor);
gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
gpfdat = gpfcon + 1;
gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
gpgdat = gpgcon + 1;
return 0;
}
static void drv_exit(void)
{
unregister_chrdev(major, "drv"); // 解除安裝
class_device_unregister(drv_class_dev);
class_destroy(drv_class);
iounmap(gpfcon);
iounmap(gpgcon);
}
module_init(drv_init);
module_exit(drv_exit);
MODULE_AUTHOR("xxx");
MODULE_VERSION("0.1.0");
MODULE_DESCRIPTION("S3C2410/S3C2440 LED Driver");
MODULE_LICENSE("GPL");測試
測試執行./text /dev/xyz0 & 後臺執行
# ./test /dev/xyz0 &
# irq55
key_val = 0x3
irq55
key_val = 0x83
irq18
key_val = 0x2
irq18
key_val = 0x82
irq16
key_val = 0x1
irq16
key_val = 0x81
irq63
key_val = 0x4
irq63
key_val = 0x84使用top檢視佔用
Load average: 0.00 0.01 0.00
PID PPID USER STAT VSZ %MEM %CPU COMMAND
782 770 0 R 3096 5% 0% top
770 1 0 S 3096 5% 0% -sh
781 770 0 S 1312 2% 0% ./test /dev/xyz0使用ps檢視任務為S狀態 休眠狀態
# ps
PID Uid VSZ Stat Command
1 0 3092 S init
781 0 1312 S ./test /dev/xyz0
783 0 3096 R ps