Linux下AM335X的GPIO控制

XeonGate 2015-09-12

展开全文

本文章转自：http://bbs./thread-327156-1-1.html
1. GPIO的char型驱动，这里主要就是点个灯，感受一下驱动的设计和硬件的控制驱动程序：

#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;//定义主设备号
/*******************************************/
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");
// 打开和关闭函数
int light_open(struct inode *inode,struct file *filp)
{
struct light_dev *dev;
// 获得设备结构体指针
dev = container_of(inode->i_cdev,struct light_dev,cdev);
// 让设备结构体作为设备的私有信息
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,
};
// 模块加载函数
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;
}
// 模块卸载函数
void light_cleanup(void)
{
unregister_chrdev(major,NAME);
printk("Goodbye,cruel world!\n");
}
module_init(light_init);
module_exit(light_cleanup);

应用程序：

#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文件：

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