[原创]AD22151霍尔元件使用实践
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发表于 6/12/2012 11:08:42 AM
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霍尔元件又叫干簧门磁。我用磁铁靠近霍尔开关，观察开关变化，同时模块上的 LED 灯会有开关状态显示，这个功能在很多地方都有用处，下面我写一下这个的使用过程。
$ cd hall/
ls
cd driver/
ls
需要修改 Makfile 编译规则文件，在其中指定用户自己的内核源文件目录（用linux2.6.24内核，并保证该内核源码解压后至少编译过一次，才能正确编译内核驱动程序）
通过修改宏KERNELDIR ?变量来指定内核源码目录：使用make命令编译红外驱动程序
make
ls
hall_switch.c hall_switch.mod.c hall_switch.o
Module.symvers
hall_switch.ko hall_switch.mod.o Makefile
[sprife@localhost driver]$
当前目录下生成驱动程序hall_switch.ko
编译应用程序.此时当前目录生成测试文件hall_switch_test
附驱动程序：#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>
#define DEVICE_NAME "hall_switch"
#define hall_MAJOR 236
#define hall_MAJOR 236
struct hall_irq_desc {
int irq;
unsigned long flags;
char *name;
};
int irq;
unsigned long flags;
char *name;
};
static struct hall_irq_desc hall_irqs [] = {
{IRQ_EINT4, IRQF_TRIGGER_RISING, "reed"},
{IRQ_EINT6, IRQF_TRIGGER_RISING, "hall"},
};
{IRQ_EINT4, IRQF_TRIGGER_RISING, "reed"},
{IRQ_EINT6, IRQF_TRIGGER_RISING, "hall"},
};
static volatile int press_cnt [] = {0,0};
static DECLARE_WAIT_QUEUE_HEAD(hall_waitq);
static volatile int ev_press = 0;
static irqreturn_t hall_interrupt(int irq, void *dev_id)
{
volatile int *press_cnt = (volatile int *)dev_id;
*press_cnt = *press_cnt + 1;
ev_press = 1;
wake_up_interruptible(&hall_waitq);
return IRQ_RETVAL(IRQ_HANDLED);
}
static int hall_open(struct inode *inode, struct file *file)
{
int i;
int err;
for (i = 0; i < sizeof(hall_irqs)/sizeof(hall_irqs[0]); i++) {
err = request_irq(hall_irqs[i].irq, hall_interrupt, hall_irqs[i].flags, hall_irqs[i].name, (void *)&press_cnt[i]);
if (err)
break;
}
{
int i;
int err;
for (i = 0; i < sizeof(hall_irqs)/sizeof(hall_irqs[0]); i++) {
err = request_irq(hall_irqs[i].irq, hall_interrupt, hall_irqs[i].flags, hall_irqs[i].name, (void *)&press_cnt[i]);
if (err)
break;
}
if (err) {
i--;
for (; i >= 0; i--)
free_irq(hall_irqs[i].irq, (void *)&press_cnt[i]);
return -EBUSY;
}
return 0;
}
i--;
for (; i >= 0; i--)
free_irq(hall_irqs[i].irq, (void *)&press_cnt[i]);
return -EBUSY;
}
return 0;
}
static int hall_close(struct inode *inode, struct file *file)
{
int i;
for (i = 0; i < sizeof(hall_irqs)/sizeof(hall_irqs[0]); i++) {
free_irq(hall_irqs[i].irq, (void *)&press_cnt[i]);
}
{
int i;
for (i = 0; i < sizeof(hall_irqs)/sizeof(hall_irqs[0]); i++) {
free_irq(hall_irqs[i].irq, (void *)&press_cnt[i]);
}
return 0;
}
}
static int hall_read(struct file *filp, char __user *buff,
size_t count, loff_t *offp)
{
unsigned long err;
wait_event_interruptible(hall_waitq, ev_press);
size_t count, loff_t *offp)
{
unsigned long err;
wait_event_interruptible(hall_waitq, ev_press);
ev_press = 0;
err = copy_to_user(buff, (const void *)press_cnt, min(sizeof(press_cnt), count));
memset((void *)press_cnt, 0, sizeof(press_cnt));
memset((void *)press_cnt, 0, sizeof(press_cnt));
return err ? -EFAULT : 0;
}
}
static struct file_operations hall_fops = {
.owner = THIS_MODULE,
.open = hall_open,
.release = hall_close,
.read = hall_read,
};
.owner = THIS_MODULE,
.open = hall_open,
.release = hall_close,
.read = hall_read,
};
static int __init hall_init(void)
{
int ret;
{
int ret;
ret = register_chrdev(hall_MAJOR, DEVICE_NAME, &s3c24xx_hall_fops);
if (ret < 0) {
printk(DEVICE_NAME " can't register major number\n");
return ret;
}
printk(DEVICE_NAME " initialized\n");
return 0;
}
if (ret < 0) {
printk(DEVICE_NAME " can't register major number\n");
return ret;
}
printk(DEVICE_NAME " initialized\n");
return 0;
}
static void __exit hall_exit(void)
{
unregister_chrdev(hall_MAJOR, DEVICE_NAME);
}
{
unregister_chrdev(hall_MAJOR, DEVICE_NAME);
}
module_init(s3c24xx_hall_init);
module_exit(s3c24xx_hall_exit);
module_exit(s3c24xx_hall_exit);
MODULE_AUTHOR("UP-TECH");
MODULE_DESCRIPTION("UP-MAGIC HALL_SWITCH Driver");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("UP-MAGIC HALL_SWITCH Driver");
MODULE_LICENSE("GPL");
收获很大，最近很辛苦，公司催的要命啊
