am335x gpio 控制的另一种方法
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/slab.h>
/*-----------------------------------------------------*/
#define DEVICE_NAME "kio"
#define GPIO_TO_PIN(bank, gpio) (32 * (bank) + (gpio))
/*------------------------------------------------------*/
struct gpio_qset;
/*设备编号存储结构体*/
struct dev_num
{
dev_t devNum;
unsigned int major;
unsigned int minor;
unsigned int minor_first;
unsigned int count;
};
struct dev_num gpio_dev_num;
/*设备描述结构体*/
struct gpio_dev
{
struct cdev cdev;
struct gpio_qset* dptr; //设备数据存储链表第一项
unsigned long size; //链表长度(随着申请的GPIO端口数增长)
};
struct gpio_dev *gpio_devp;
/*设备数据存储结构体(采用链式存储,不理解的可以看《数据结构》)*/
struct gpio_qset
{
unsigned long port; //端口号 #define GPIO_TO_PIN(bank, gpio) (32 * (bank) + (gpio))
unsigned int ddr; //方向（输入(0)或输出(1)）
char value; //高(1)低(0)电平
unsigned long num; //当前编号(按照申请顺序编号)
char label[10]; //申请的GPIO使用名称
struct gpio_qset* next; //指向链表下一项的指针
};
/**
* 功能:初始化gpio_dev
* *inode:
* *filp:
* 描述:用户空间调用open时运行
* int (*open) (struct inode *, struct file *);
* 返回值:0
*/
static int gpio_open(struct inode *inode, struct file *filp)
{
struct gpio_dev *dev;
//由container_of获得结构体指针inode中结构体cdev的指针，
//让结构体指针dev指向上述的指针所指的地址，
//再让file->private指向这一地址，
dev = container_of(inode->i_cdev, struct gpio_dev, cdev);
filp->private_data = dev;
dev->dptr = NULL;
dev->size = 0;
//printk(KERN_ERR "gpio_open success!\n");
return 0;
}
/**
* 功能:释放申请的GPIO端口以及释放链表(gpio_qset)
* *inode:
* *filp:
* 描述:用户空间调用close时运行
* int (*release) (struct inode *, struct file *);
* 返回值:0
*/
static int gpio_close(struct inode *inode, struct file *filp)
{
struct gpio_dev *dev = filp->private_data;
struct gpio_qset *qset, *qsetTmp;
qsetTmp = (struct gpio_qset *)kzalloc(sizeof(struct gpio_qset), GFP_KERNEL);
for(qset = dev->dptr; qset->next !=NULL; qset=qsetTmp)
{
qsetTmp = qset->next;
gpio_free(qset->port); //释放申请的端口
kfree(qset); //释放gpio_qset内存
}
gpio_free(qsetTmp->port);
kfree(qsetTmp);
//printk(KERN_ERR "gpio release!\n");
return 0;
}
/**
* 功能:申请新的gpio_qset的内存，确定相应的GPIO端口功能
* *inode:
* *filp:
* cmd:实现的功能，
* 0：读，
* 1：写，
* 2：释放GPIO端口
* arg:执行操作的GPIO端口
* 描述:用户空间调用ioctl时运行
* long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
* 返回值:成功返回操作的GPIO端口号
* 错误返回相应的错误码
*/
static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
int ret;
struct gpio_dev *dev = filp->private_data;
struct gpio_qset *qset;
//cmd == 2 设计成为释放arg端口的功能，之后申请内存的任务便不必执行了，所以直接返回
if(cmd == 2)
{
gpio_free(arg);
return arg;
}
dev->size++;
if(dev->dptr == NULL)
{
dev->dptr = (struct gpio_qset *)kzalloc(sizeof(struct gpio_qset), GFP_KERNEL);
qset = dev->dptr;
}
else
{
for(qset = dev->dptr; qset->next != NULL; qset = qset->next); //找到链表最后一项
qset->next = (struct gpio_qset *)kzalloc(sizeof(struct gpio_qset), GFP_KERNEL);
qset = qset->next;
}
/*链表数据*/
qset->num = dev->size; //确定自己的编号
qset->ddr = cmd; //确定方向
qset->port = arg; //确定端口号
qset->next = NULL; //最后一项地址清空
//printk(KERN_ERR "qset->num=%d,qset->ddr=%d,qset->port=%d\n", qset->num, qset->ddr, qset->port);
sprintf(qset->label, "gpio%ld", qset->port); //确定申请的GPIO使用名称(和端口直接相关)
ret = gpio_request(qset->port, qset->label); //申请端口
/*由于gpio_requset会自己判断成功与否并且退出函数，故注释掉对ret的判断
if(ret < 0)
printk(KERN_ERR "%s_requset failled!%d \n", qset->label, ret);
*/
/*判断GPIO工作方向(输出或输出)*/
switch(qset->ddr)
{
case 0:
ret = gpio_direction_input(qset->port);
if(ret < 0)
printk(KERN_ERR "gpio_direction_input failled!\n");
break;
case 1:
ret = gpio_direction_output(qset->port, 1);
if(ret < 0)
printk(KERN_ERR "gpio_direction_output failled!\n");
break;
default:
return -EPERM; /* Operation not permitted */
}
return qset->num;
}
/**
* 功能:获取相应端口电平，写入相应的qset_dev->value，写到用户空间的readBuf
* *inode:
* *filp:
* *readBuf:读数据缓存指针，用户空间的指针
* port:被读取的GPIO端口号
* *offp:
* 描述:用户空间调用read时运行
* ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
* 返回值:成功返回qset->value
* 错误返回相应的错误码
*/
static ssize_t gpio_read (struct file *filp, char __user *readBuf, size_t port, loff_t *offp)
{
long ret;
struct gpio_dev *dev = filp->private_data;
struct gpio_qset *qset;
if(dev->dptr == NULL)
return -ENODEV; /* No such device */
for(qset = dev->dptr; qset != NULL; qset = qset->next)
{
if(qset->port == port)
break;
if(qset->next == NULL)
return -ENODEV; /* No such device */
}
if(qset->ddr != 0) //判断是否ioctl设置为读操作
return -EPERM; /* Operation not permitted */
qset->value = gpio_get_value(qset->port);
//printk(KERN_ERR "qset->port:%d, qset->value:%d\n", qset->port, qset->value);
switch(qset->value)
{
case 0:
ret = copy_to_user(readBuf, "0", 1);
break;
case 1:
ret = copy_to_user(readBuf, "1", 1);
break;
}
return qset->value;
}
/**
* 功能:写入相应端口电平，写入相应的qset_dev->value，数据来自用户空间的writeBuf
* *inode:
* *filp:
* *writeBuf:写数据缓存指针，用户空间的指针
* port:被写入的GPIO端口号
* *offp:
* 描述:用户空间调用write时运行
* ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
* 返回值:成功返回qset->value
* 错误返回相应的错误码
*/
static ssize_t gpio_write (struct file *filp, const char __user *writeBuf, size_t port, loff_t *offp)
{
long ret;
struct gpio_dev *dev = filp->private_data;
struct gpio_qset *qset;
if(dev->dptr == NULL)
return -ENODEV; /* No such device */
for(qset = dev->dptr; qset != NULL; qset = qset->next)
{
// printk(KERN_ERR "qset->port=%d,port=%d\n", qset->port, port);
if(qset->port == port)
break;
if(qset->next == NULL)
return -ENODEV; /* No such device */
}
if(qset->ddr != 1) //判断是否ioctl设置为写操作
return -EPERM; /* Operation not permitted */
ret = copy_from_user(&qset->value, writeBuf, 1);
//printk(KERN_ERR "write:%d\n", qset->value);
switch(qset->value)
{
case '0': qset->value = 0;
gpio_set_value(qset->port, 0);
break;
default : qset->value = 1;
gpio_set_value(qset->port, 1);
break;
}
return qset->value;
}
/*文件操作结构体*/
static const struct file_operations gpio_fops = {
.owner = THIS_MODULE,
.open = gpio_open,
.unlocked_ioctl = gpio_ioctl,
.write = gpio_write,
.read = gpio_read,
.release = gpio_close,
};
/*cdev注册函数*/
static void gpio_setup_cdev(struct gpio_dev *dev, int index)
{
int ret,devno = gpio_dev_num.devNum + index;
cdev_init(&dev->cdev, &gpio_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &gpio_fops;
ret = cdev_add(&dev->cdev, devno, 1);
if(ret)
printk(KERN_ERR "error %d : adding gpioCtl%d",ret,index);
}
static struct class *kio_class;
/*设备初始化函数*/
static int __init omap2gpio_init(void)
{
int ret;
gpio_dev_num.count = 1;
gpio_dev_num.minor_first = 0;
ret = alloc_chrdev_region(&gpio_dev_num.devNum,
gpio_dev_num.minor_first,
gpio_dev_num.count,
DEVICE_NAME);
if(ret < 0)
return ret;
gpio_dev_num.major = MAJOR(gpio_dev_num.devNum);
gpio_dev_num.minor = MINOR(gpio_dev_num.devNum);
gpio_devp = kzalloc(sizeof(struct gpio_dev),GFP_KERNEL);
gpio_setup_cdev(gpio_devp, 0);
printk(KERN_ERR "gpio alloc_chrdev_region success, major = %d\n",
gpio_dev_num.major);
kio_class = class_create(THIS_MODULE, DEVICE_NAME);
device_create(kio_class, //pointer to the struct class that this device should be registered to
NULL,
gpio_dev_num.devNum, //the dev_t for the char device to be added
NULL,
"%s",
DEVICE_NAME);
return 0;
}
/*设备释放函数*/
static void __exit omap2gpio_exit(void)
{
cdev_del(&gpio_devp->cdev);
kfree(gpio_devp);
unregister_chrdev_region(gpio_dev_num.devNum, 1);
device_destroy(kio_class, gpio_dev_num.devNum); //the dev_t for the char device to be added
class_destroy(kio_class);
printk(KERN_ERR "gpio unregister_chrdev_region success, major = %d\n",
gpio_dev_num.major);
}
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Mlo_Lv,Tute-421E-studio");
MODULE_DESCRIPTION("This module is used to conrtol ti omap2 gpio");
module_init(omap2gpio_init);
module_exit(omap2gpio_exit);
