linux下AM335X的GPIO控制

linux下AM335X的GPIO控制

作者：chenzhufly QQ：36886052 ( 轉載請註明出處)
一路走來，熟悉硬體系統，搭建軟體開發環境，編譯Linux系統等等，現在也該到對硬體做一些事情了，這是我這幾天的研究心得，與君共用。

1. GPIO的char型驅動，這裡主要就是點個燈，感受一下驅動的設計和硬體的控制驅動程式：

複製內容到剪貼簿代碼:#include <linux/init.h>
#include <linux/module.h>
#include <linux/leds.h>
#include <linux/io.h>

#include <linux/semaphore.h>
#include <linux/kernel.h>
#include <linux/cdev.h>

#include <linux/types.h>
#include <linux/fs.h>
#include <mach/gpio.h>
#include <plat/mux.h>

#include <linux/gpio.h>

/*******************************************/
#define NAME \"leds\" 
#define GPIO_TO_PIN(bank, gpio) (32 * (bank) + (gpio))

static int major =251;//定義主裝置號 
/*******************************************/
void led_on(void)
{ 
gpio_set_value(GPIO_TO_PIN(1,22), 1);
}

void led_off(void)
{ 
gpio_set_value(GPIO_TO_PIN(1,22), 0);
}

void led_init(void)
{ 
int result;
/* Allocating GPIOs and setting direction */
result = gpio_request(GPIO_TO_PIN(1,22), \"Leds\");//usr1
if (result != 0)
printk(\"gpio_request(1_22) failed!\n\");
result = gpio_direction_output(GPIO_TO_PIN(1,22), 1);
if (result != 0)
printk(\"gpio_direction(1_22) failed!\n\");

}

struct light_dev
{
struct cdev cdev;
unsigned char value;
};

struct light_dev *light_devp;

MODULE_AUTHOR(\"chenzhufly\");
MODULE_LICENSE(\"Dual BSD/GPL\");

// 開啟和關閉函數
int light_open(struct inode *inode,struct file *filp)
{
struct light_dev *dev;

// 獲得裝置結構體指標
dev = container_of(inode->i_cdev,struct light_dev,cdev);
// 讓裝置結構體作為裝置的私人資訊
filp->private_data = dev;

return 0;
}

int light_release(struct inode *inode,struct file *filp)
{
return 0; 
}

// ioctl
int light_ioctl(struct file *filp,unsigned int cmd,
unsigned long arg)
{
struct light_dev *dev = filp->private_data;

switch(cmd)
{
case 0:
dev->value = 0;
led_off(); 
break;

case 1:
dev->value = 1;
led_on();
break;

default:

return -ENOTTY;
// break;
}

return 0;
} 

struct file_operations light_fops = 
{
.owner = THIS_MODULE,
.unlocked_ioctl = light_ioctl,
.open = light_open,
.release = light_release,
};
// 模組載入函數
int light_init(void)
{
int ret;
led_init();
printk(KERN_ALERT \"led modules is install\n\"); 
ret=register_chrdev(major,NAME,&light_fops); 
if(ret<0) 
{ 
printk(\"unable to register myled driver!\n\"); 
return ret; 
} 
return 0; 

}

// 模組卸載函數
void light_cleanup(void)
{
unregister_chrdev(major,NAME); 
printk(\"Goodbye,cruel world!\n\"); 
}

module_init(light_init);
module_exit(light_cleanup);

應用程式：

複製內容到剪貼簿代碼:#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/input.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main(int argc, char * argv)
{
int i, n, fd;

fd = open(\"/dev/leds\", O_RDWR);
if (fd < 0)
{
printf(\"can't open /dev/leds!\n\");
exit(1);
}

while (1) {
ioctl(fd, 1, 1);
sleep(1);

ioctl(fd, 0, 1);
sleep(1);
}

close(fd);

return 0;
}

Makefile檔案：

複製內容到剪貼簿代碼:ARCH=arm
CROSS_COMPILE=/home/chenzhufly/beaglebone/linux-devkit/bin/arm-arago-linux-gnueabi-
obj-m := leds.o
KDIR := /home/chenzhufly/beaglebone/board-support/linux-3.1.0-psp04.06.00.03.sdk
PWD := $(shell pwd)
default:
make -C $(KDIR) M=$(PWD) ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) modules
app: leds_test.c
$(CROSS_COMPILE)gcc -o leds_test leds_test.c
clean:
$(MAKE) -C $(KDIR) M=$(PWD) clean

leds.sh指令碼

複製內容到剪貼簿代碼:insmod leds.ko
mknod /dev/leds c 251 0
./leds_test

2. 使用echo命令，這個我在前面也說過

複製內容到剪貼簿代碼:點亮usr1
root@beaglebone:~# echo 1 >
/sys/class/leds/beaglebone::usr1/brightness

關閉usr1
root@beaglebone:~# echo 0 > /sys/class/leds/beaglebone::usr1/brightness

3. 做個應用程式實現流水燈功能吧

複製內容到剪貼簿代碼:#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/ioctl.h>
#include <fcntl.h> 
#define LED1 \"/sys/class/leds/beaglebone::usr1/brightness\" // usr1 led
#define LED2 \"/sys/class/leds/beaglebone::usr2/brightness\" // usr2 led
#define LED3 \"/sys/class/leds/beaglebone::usr3/brightness\" // usr3 led

int main(void)
{
int f_led1 = open(LED1, O_RDWR);
int f_led2 = open(LED2, O_RDWR);
int f_led3 = open(LED3, O_RDWR);

unsigned char dat1, dat2, dat3;
unsigned char i = 0;

if (f_led1 < 0)
{ 
printf(\"error in open %s\",LED1);
return -1;
} 
if (f_led2 < 0)
{
printf(\"error in open %s\",LED2);
return -1;
} 
if (f_led3 < 0) 
{
printf(\"error in open %s\",LED3);
return -1;
} 
//add 10 times
for(i=1; i<30; i++)
{
dat1 = ((i%3) == 1) ? '1' : '0';
dat2 = ((i%3) == 2) ? '1' : '0';
dat3 = ((i%3) == 0) ? '1' : '0';
write(f_led1, &dat1, sizeof(dat1));
write(f_led2, &dat2, sizeof(dat2));
write(f_led3, &dat3, sizeof(dat3));
usleep(300000);
} 
// all the bright
{
dat1 = '1';
dat2 = '1';
dat3 = '1';
write(f_led1, &dat1, sizeof(dat1));
write(f_led2, &dat2, sizeof(dat2));
write(f_led3, &dat3, sizeof(dat3));
} 
}