#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>
#define DEVICE_NAME "leds" /* 加載模式後,執行”cat /proc/devices”命令看到的設備名稱 */
#define LED_MAJOR 231 /* 主設備號 */
static struct class *leds_class;
static struct class_device *leds_class_devs[4];
/* bit0<=>D10, 0:亮, 1:滅
* bit1<=>D11, 0:亮, 1:滅
* bit2<=>D12, 0:亮, 1:滅
*/
static char leds_status = 0x0;
static DECLARE_MUTEX(leds_lock); // 定義賦值
//static int minor;
static unsigned long gpio_va;
#define GPIO_OFT(x) ((x) - 0x56000000)
#define GPFCON (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000050)))
#define GPFDAT (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000054)))
/* 應用程序對設備文件/dev/leds執行open(...)時,
* 就會調用s3c24xx_leds_open函數
*/
static int s3c24xx_leds_open(struct inode *inode, struct file *file)
{
int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);
switch(minor)
{
case 0: /* /dev/leds */
{
// 配置3引腳爲輸出
GPFCON &= ~(0x3<<(4*2));
GPFCON |= (1<<(4*2));
GPFCON &= ~(0x3<<(5*2));
GPFCON |= (1<<(5*2));
GPFCON &= ~(0x3<<(6*2));
GPFCON |= (1<<(6*2));
// 都輸出0
//s3c2410_gpio_setpin(S3C2410_GPF4, 0);
GPFDAT &= ~(1<<4);
//s3c2410_gpio_setpin(S3C2410_GPF5, 0);
GPFDAT &= ~(1<<5);
//s3c2410_gpio_setpin(S3C2410_GPF6, 0);
GPFDAT &= ~(1<<6);
down(&leds_lock);
leds_status = 0x0;
up(&leds_lock);
break;
}
}
return 0;
}
static int s3c24xx_leds_read(struct file *filp, char __user *buff,
size_t count, loff_t *offp)
{
int minor = MINOR(filp->f_dentry->d_inode->i_rdev);
char val;
switch (minor)
{
case 0: /* /dev/leds */
{
copy_to_user(buff, (const void *)&leds_status, 1);
break;
}
}
return 1;
}
static ssize_t s3c24xx_leds_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
int minor = MINOR(file->f_dentry->d_inode->i_rdev);
char val;
copy_from_user(&val, buf, 1);
switch (minor)
{
case 0: /* /dev/leds */
{
s3c2410_gpio_setpin(S3C2410_GPF4, (val & 0x1));
s3c2410_gpio_setpin(S3C2410_GPF5, (val & 0x1));
s3c2410_gpio_setpin(S3C2410_GPF6, (val & 0x1));
down(&leds_lock);
leds_status = val;
up(&leds_lock);
break;
}
}
return 1;
}
/* 這個結構是字符設備驅動程序的核心
* 當應用程序操作設備文件時所調用的open、read、write等函數,
* 最終會調用這個結構中指定的對應函數
*/
static struct file_operations s3c24xx_leds_fops = {
.owner = THIS_MODULE, /* 這是一個宏,推向編譯模塊時自動創建的__this_module變量 */
.open = s3c24xx_leds_open,
.read = s3c24xx_leds_read,
.write = s3c24xx_leds_write,
};
/*
* 執行insmod命令時就會調用這個函數
*/
static int __init s3c24xx_leds_init(void)
{
int ret;
int minor = 0;
gpio_va = ioremap(0x56000000, 0x100000);
if (!gpio_va) {
return -EIO;
}
/* 註冊字符設備
* 參數爲主設備號、設備名字、file_operations結構;
* 這樣,主設備號就和具體的file_operations結構聯繫起來了,
* 操作主設備爲LED_MAJOR的設備文件時,就會調用s3c24xx_leds_fops中的相關成員函數
* LED_MAJOR可以設爲0,表示由內核自動分配主設備號
*/
ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &s3c24xx_leds_fops);
if (ret < 0) {
printk(DEVICE_NAME " can't register major number\n");
return ret;
}
printk(DEVICE_NAME "Lesson1 initialized\n");
return 0;
}
/*
* 執行rmmod命令時就會調用這個函數
*/
static void __exit s3c24xx_leds_exit(void)
{
int minor;
/* 卸載驅動程序 */
unregister_chrdev(LED_MAJOR, DEVICE_NAME);
#if 0
for (minor = 0; minor < 4; minor++)
{
class_device_unregister(leds_class_devs[minor]);
}
class_destroy(leds_class);
#endif
iounmap(gpio_va);
}
/* 這兩行指定驅動程序的初始化函數和卸載函數 */
module_init(s3c24xx_leds_init);
module_exit(s3c24xx_leds_exit);
/* 描述驅動程序的一些信息,不是必須的 */
MODULE_AUTHOR("http://www.100ask.net");
MODULE_VERSION("0.1.0");
MODULE_DESCRIPTION("S3C2410/S3C2440 LED Driver");
MODULE_LICENSE("GPL");
原理圖:
由此看到 低電平有效;