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字符设备驱动之Buttons-循环缓冲队列+非阻塞访问

2011-09-14 17:16 357 查看
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>

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;

};

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;

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)

{

struct key_desc *kd = (struct key_desc *)dev_id;

int up;

char key;

/* 确定按键: 哪个按键,按下还是松开 */

up = s3c2410_gpio_getpin(kd->pin); // gpfdat, gpgdat

if (up)

{

key = kd->key_val;

}

else

{

key = kd->key_val | 0x80;

}

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

putData(key);

/* 唤醒应用程序 */

wake_up_interruptible(&button_waitq);

//printk("buttons_irq current %s , pid = %d \n", current->comm, current->pid);

return IRQ_HANDLED;

}

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 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,

};

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);

return 0;

}

void buttons_exit(void)

{

unregister_chrdev(major, "buttons");

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

class_destroy(cls);

iounmap(gpecon);

}

module_init(buttons_init);

module_exit(buttons_exit);

MODULE_LICENSE("GPL");

buttons_test.c

#include <stdio.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

/* button_test [nonblock] */

int main(int argc, char **argv)

{

char buf[4];

int fd;

int ret;

if (argc == 2)/*阻塞、非阻塞访问,由应用程序决定*/

fd = open("/dev/buttons", O_RDONLY | O_NONBLOCK);

else

fd = open("/dev/buttons", O_RDONLY);

if (fd < 0)

{

printf("can't open /dev/buttons\n");

return -1;

}

while (1)

{

ret = read(fd, buf, 1);

if (ret == -1)

printf("no data\n");

else

printf("key = 0x%x\n", buf[0]);

}

return 0;

}

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