Linux下AM335X的GPIO控制

一路走來，熟悉硬件系統，搭建軟件開發環境，編譯Linux系統等等，現在也該到對硬件做一些事情了，這是我這幾天的研究心得，與君共享。

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件的控制驅動程序：

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;//定義主設備號
/*******************************************/
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\");

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

// 獲得設備結構體指針
dev = container_of(inode->i_cdev,struct light_dev,cdev);
// 讓設備結構體作為設備的私有信息
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,
};
// 模塊加載函數
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;

}

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

module_init(light_init);
module_exit(light_cleanup);