上篇文章中斷按鍵的驅動跨度有點大,這裏面揉合了太多的東西,所以特地再重新寫以下,以加強理解:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>
#include <mach/map.h>
#include <mach/gpio.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#define DEVICE_NAME "buttons"
#define BUTTON_MAJOR 254
#define KEY_STATUS_DOWN '0'
#define KEY_STATUS_UP '1'
struct button_desc {
int gpio;
int number;
char *name;
};
static struct button_desc buttons[] = {
{ S5PV210_GPH2(0), 0, "KEY0" },
{ S5PV210_GPH2(1), 1, "KEY1" },
{ S5PV210_GPH2(2), 2, "KEY2" },
{ S5PV210_GPH2(3), 3, "KEY3" },
{ S5PV210_GPH3(0), 4, "KEY4" },
{ S5PV210_GPH3(1), 5, "KEY5" },
{ S5PV210_GPH3(2), 6, "KEY6" },
{ S5PV210_GPH3(3), 7, "KEY7" },
};
static volatile char key_states[] = {
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP
};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press = 0;
static irqreturn_t button_interrupt(int irq, void *dev_id)
{
struct button_desc *bdata = (struct button_desc *)dev_id;
if(gpio_get_value(bdata->gpio) == 0)//when press down
{
key_states[bdata->number]=KEY_STATUS_DOWN;
ev_press = 1;
wake_up_interruptible(&button_waitq);
}
else
{
key_states[bdata->number]=KEY_STATUS_UP;
}
return IRQ_HANDLED;
}
static ssize_t smart210_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp){
unsigned long err;
wait_event_interruptible(button_waitq, ev_press);
ev_press = 0;
err = copy_to_user((void *)buff, (const void *)(&key_states),
min(sizeof(key_states), count));
return err ? -EFAULT : min(sizeof(key_states), count);
};
static int smart210_buttons_open(struct inode *inode, struct file *file){
int i;
int err;
int irq;
for(i=0;i< ARRAY_SIZE(buttons);i++){
//註冊中斷函數
irq = gpio_to_irq(buttons[i].gpio);
err = request_irq(irq, button_interrupt, IRQ_TYPE_EDGE_BOTH,
buttons[i].name, (void *)&buttons[i]);
if (err)
break;
}
if(err)
{
i--;
for (; i >= 0; i--) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
disable_irq(irq);
free_irq(irq, (void *)&buttons[i]);
}
return -EBUSY;
}
return 0;
};
static int smart210_buttons_close(struct inode *inode, struct file *file){
int irq, i;
for (i = 0; i < ARRAY_SIZE(buttons); i++) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
free_irq(irq, (void *)&buttons[i]);
}
return 0;
};
static struct file_operations smart210_buttons_dev_fops = {
.owner = THIS_MODULE,
.open =smart210_buttons_open,
.release =smart210_buttons_close,
.read =smart210_buttons_read,
};
static int __init smart210_buttons_dev_init(void) {
int ret;
//字符設備
ret=register_chrdev(BUTTON_MAJOR,DEVICE_NAME,&smart210_buttons_dev_fops);
if (ret < 0) {
printk("request char device failed\n");
return ret;
}
printk(DEVICE_NAME"\tinitialized\n");
return ret;
}
static void __exit smart210_buttons_dev_exit(void) {
//註銷字符設備
unregister_chrdev(BUTTON_MAJOR,DEVICE_NAME);
}
module_init(smart210_buttons_dev_init);
module_exit(smart210_buttons_dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
這裏少了定時器中斷的內容。原先我一直不理解爲什麼在按鍵中斷裏面又要加入定時器。等到我把定時器拿掉後,才發現。好像是爲了按鍵消抖。如果不消抖,有時候會出現按下去一下,實際驅動中會get 到按下去多次。
將設備註冊爲字符設備,而非混雜設備,這裏只是試試看兩者會有什麼差異。
實際上字符設備需要手動在dev目錄下創建設備文件,如果沒有特殊處理的話,這樣的話會非常麻煩。
首先先cat /proc/devices
由於我們是靜態分配,所以知道主設備號爲254,如果是動態分配主設備號,則安上面操作查詢主設備號!
然後在dev目錄下 mknod buttons c 254 1 創建設備文件
可見手動創建設備節點還是比較繁瑣的,misc混雜設備是可以自動生成的,很實用!
使字符設備可以自動創建設備節點:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>
#include <mach/map.h>
#include <mach/gpio.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#define DEVICE_NAME "buttons"
/*set to 0 自動分配主設備號,否則手動分配,但是如果已經被佔用,便會分配失敗*/
#define BUTTON_MAJOR 0
#define KEY_STATUS_DOWN '0'
#define KEY_STATUS_UP '1'
struct button_desc {
int gpio;
int number;
char *name;
};
static struct button_desc buttons[] = {
{ S5PV210_GPH2(0), 0, "KEY0" },
{ S5PV210_GPH2(1), 1, "KEY1" },
{ S5PV210_GPH2(2), 2, "KEY2" },
{ S5PV210_GPH2(3), 3, "KEY3" },
{ S5PV210_GPH3(0), 4, "KEY4" },
{ S5PV210_GPH3(1), 5, "KEY5" },
{ S5PV210_GPH3(2), 6, "KEY6" },
{ S5PV210_GPH3(3), 7, "KEY7" },
};
static volatile char key_states[] = {
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP
};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press = 0;
/*當用戶空間已經移植了udev/mdev,使用下列方式可以在dev目錄下自動創建字符設備*/
static struct class* buttons_class;
static dev_t dev;
static irqreturn_t button_interrupt(int irq, void *dev_id)
{
struct button_desc *bdata = (struct button_desc *)dev_id;
if(gpio_get_value(bdata->gpio) == 0)//when press down
{
key_states[bdata->number]=KEY_STATUS_DOWN;
ev_press = 1;
wake_up_interruptible(&button_waitq);
}
else
{
key_states[bdata->number]=KEY_STATUS_UP;
}
return IRQ_HANDLED;
}
static ssize_t smart210_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp){
unsigned long err;
//等待 wait隊列被喚醒,獲取值,阻塞模式訪問,沒有數據一直等待
wait_event_interruptible(button_waitq, ev_press);
ev_press = 0;
err = copy_to_user((void *)buff, (const void *)(&key_states),
min(sizeof(key_states), count));
return err ? -EFAULT : min(sizeof(key_states), count);
};
static int smart210_buttons_open(struct inode *inode, struct file *file){
int i;
int err;
int irq;
for(i=0;i< ARRAY_SIZE(buttons);i++){
//註冊中斷函數
irq = gpio_to_irq(buttons[i].gpio);
err = request_irq(irq, button_interrupt, IRQ_TYPE_EDGE_BOTH,
buttons[i].name, (void *)&buttons[i]);
if (err)
break;
}
if(err)
{
i--;
for (; i >= 0; i--) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
disable_irq(irq);
free_irq(irq, (void *)&buttons[i]);
}
return -EBUSY;
}
return 0;
};
static int smart210_buttons_close(struct inode *inode, struct file *file){
int irq, i;
for (i = 0; i < ARRAY_SIZE(buttons); i++) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
free_irq(irq, (void *)&buttons[i]);
}
return 0;
};
static struct file_operations smart210_buttons_dev_fops = {
.owner = THIS_MODULE,
.open =smart210_buttons_open,
.release =smart210_buttons_close,
.read =smart210_buttons_read,
};
static int __init smart210_buttons_dev_init(void) {
int major;
//字符設備
major=register_chrdev(BUTTON_MAJOR,DEVICE_NAME,&smart210_buttons_dev_fops);
if (major < 0) {
printk("request char device failed\n");
return major;
}
buttons_class=class_create(THIS_MODULE,DEVICE_NAME);
dev = MKDEV(major, 1);
device_create(buttons_class,NULL,dev,NULL,"%s",buttons_class->name);
printk(DEVICE_NAME"\tinitialized\n");
return major;
}
static void __exit smart210_buttons_dev_exit(void) {
//註銷字符設備
unregister_chrdev(BUTTON_MAJOR,DEVICE_NAME);
device_destroy(buttons_class, dev);
class_destroy(buttons_class);
}
module_init(smart210_buttons_dev_init);
module_exit(smart210_buttons_dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
另外還有一種方式,因爲以上驅動讀設備時阻塞訪問,一直停留在那裏等待,有點浪費資源!
我們可以用poll的方式:poll裏面有一個timeout參數,比如poll一個設備50ms,如果在50ms內設備可以進行某些操作,比如
可以被讀,或者IO允許被寫,此時我們再直接調用read函數或者write函數,便可以直接獲得/操作數據.
如果50ms內設備返回 0,即超時。我們此時可以選擇繼續poll或者做其他事情。
這裏主要研究下poll函數的作用!
最後的驅動這樣寫:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>
#include <mach/map.h>
#include <mach/gpio.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#define DEVICE_NAME "buttons"
/*set to 0 自動分配主設備號,否則手動分配,但是如果已經被佔用,便會分配失敗*/
#define BUTTON_MAJOR 0
#define KEY_STATUS_DOWN '0'
#define KEY_STATUS_UP '1'
struct button_desc {
int gpio;
int number;
char *name;
};
static struct button_desc buttons[] = {
{ S5PV210_GPH2(0), 0, "KEY0" },
{ S5PV210_GPH2(1), 1, "KEY1" },
{ S5PV210_GPH2(2), 2, "KEY2" },
{ S5PV210_GPH2(3), 3, "KEY3" },
{ S5PV210_GPH3(0), 4, "KEY4" },
{ S5PV210_GPH3(1), 5, "KEY5" },
{ S5PV210_GPH3(2), 6, "KEY6" },
{ S5PV210_GPH3(3), 7, "KEY7" },
};
static volatile char key_states[] = {
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP
};
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press = 0;
/*當用戶空間已經移植了udev/mdev,使用下列方式可以在dev目錄下自動創建字符設備*/
static struct class* buttons_class;
static dev_t dev;
static irqreturn_t button_interrupt(int irq, void *dev_id)
{
struct button_desc *bdata = (struct button_desc *)dev_id;
if(gpio_get_value(bdata->gpio) == 0)//when press down
{
key_states[bdata->number]=KEY_STATUS_DOWN;
ev_press = 1;
wake_up_interruptible(&button_waitq);
}
else
{
key_states[bdata->number]=KEY_STATUS_UP;
}
return IRQ_HANDLED;
}
static ssize_t smart210_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp){
unsigned long err;
if (!ev_press) {
if (filp->f_flags & O_NONBLOCK){
printk("noneblock return\n");
return -EAGAIN;
}
}
ev_press = 0;
err = copy_to_user((void *)buff, (const void *)(&key_states),
min(sizeof(key_states), count));
return err ? -EFAULT : min(sizeof(key_states), count);
};
static int smart210_buttons_open(struct inode *inode, struct file *file){
int i;
int err;
int irq;
for(i=0;i< ARRAY_SIZE(buttons);i++){
//註冊中斷函數
irq = gpio_to_irq(buttons[i].gpio);
err = request_irq(irq, button_interrupt, IRQ_TYPE_EDGE_BOTH,
buttons[i].name, (void *)&buttons[i]);
if (err)
break;
}
if(err)
{
i--;
for (; i >= 0; i--) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
disable_irq(irq);
free_irq(irq, (void *)&buttons[i]);
}
return -EBUSY;
}
return 0;
};
static int smart210_buttons_close(struct inode *inode, struct file *file){
int irq, i;
for (i = 0; i < ARRAY_SIZE(buttons); i++) {
if (!buttons[i].gpio)
continue;
irq = gpio_to_irq(buttons[i].gpio);
free_irq(irq, (void *)&buttons[i]);
}
return 0;
};
static unsigned int smart210_buttons_poll( struct file *file,
struct poll_table_struct *wait)
{
unsigned int mask = 0;
poll_wait(file, &button_waitq, wait);
if (ev_press)
mask |= POLLIN | POLLRDNORM;/*key is press down,IO is readable*/
return mask;
}
static struct file_operations smart210_buttons_dev_fops = {
.owner = THIS_MODULE,
.open =smart210_buttons_open,
.release =smart210_buttons_close,
.read =smart210_buttons_read,
.poll =smart210_buttons_poll,
};
static int __init smart210_buttons_dev_init(void) {
int major;
//字符設備
major=register_chrdev(BUTTON_MAJOR,DEVICE_NAME,&smart210_buttons_dev_fops);
if (major < 0) {
printk("request char device failed\n");
return major;
}
buttons_class=class_create(THIS_MODULE,DEVICE_NAME);
dev = MKDEV(major, 1);
device_create(buttons_class,NULL,dev,NULL,"%s",buttons_class->name);
printk(DEVICE_NAME"\tinitialized\n");
return major;
}
static void __exit smart210_buttons_dev_exit(void) {
//註銷字符設備
unregister_chrdev(BUTTON_MAJOR,DEVICE_NAME);
device_destroy(buttons_class, dev);
class_destroy(buttons_class);
}
module_init(smart210_buttons_dev_init);
module_exit(smart210_buttons_dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
這邊的差別是:如果打開文件,接下來直接read ,因爲沒有按鍵按下時,就直接返回一個負數,而不會等待。
所以測試程序的編寫需要改變下:
先打開文件,然後poll ,傳給內核驅動中的poll,有一個timeout時間,如果在timeout時間內返回可讀,此時調用read函數直接讀取,否則,重新poll。
測試程序:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h>
#include <termios.h>
#include <sys/poll.h>
#include <string.h>
#define KEY_STATUS_DOWN '0'
#define KEY_STATUS_UP '1'
/*main timeouttime*/
int main(int argc, char **argv)
{
int buttons_fd;
int ret;
int timeoutcount;
char current_buttons[8] = {
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP,
KEY_STATUS_UP
};
struct pollfd event; //創建一個struct pollfd結構體變量,存放文件描述符、要等待發生的事件
if(argc !=2 || sscanf(argv[1], "%d", &timeoutcount) !=1 || timeoutcount <40){
printf("USE like : ./buttons timeout(40-)\n");
exit(1);
}
buttons_fd = open("/dev/buttons", O_NONBLOCK);//非阻塞方式
if (buttons_fd < 0) {
perror("open device buttons");
exit(1);
}
while(timeoutcount--){
int i;
//poll結束後struct pollfd結構體變量的內容被全部清零,需要再次設置
memset(&event,0,sizeof(event)); //memst函數對對象的內容設置爲同一值
event.fd=buttons_fd; //存放打開的文件描述符
event.events=POLLIN; //存放要等待發生的事件
ret=poll((struct pollfd *)&event,1,100); //監測event,一個對象,等待100毫秒後超時,-1爲無限等待
//判斷poll的返回值,負數是出錯,0是設定的時間超時,整數表示等待的時間發生
if(ret<0){
printf("poll error!\n");
exit(1);
}
if(ret==0){
//printf("Time out!\n");
continue;
}
if(event.revents&POLLERR){ //revents是由內核記錄的實際發生的事件,events是進程等待的事件
printf("Device error!\n");
exit(1);
}
//poll in
if(event.revents&POLLIN){
read(buttons_fd, current_buttons, sizeof(current_buttons));
for (i = 0; i < sizeof(current_buttons) / sizeof(current_buttons[0]); i++) {
if (current_buttons[i] ==KEY_STATUS_DOWN) {
printf("The key %d is pressed down!\n",i);
}
}
}
}
printf("Time out close file\n");
close(buttons_fd);
return 0;
}
大概說明一個;測試程序傳入一個參數n,當n*timeout(poll的timeout時間爲100ms)後,自動關掉設備文件。
在這段時間之間,如果有某些按鍵按下,當前被按下的按鍵都會被打印出來。
這裏的驅動程序其實已經和開發板上的按鍵驅動程序非常相近了。如果我在這裏再把定時器消抖的函數拿進來,那麼其實就和例程是一樣的。
到此,按鍵驅動開發結束!