Linux下CPLD驱动程序

/* ========================================================================== */
/*                                                                            */
/*   Filename.c                                                               */
/*   (c) 2001 Author  Zhang Haibo                                             */
/*                                                                            */
/*   Description  driver program with interrupt and poll                      */
/*                                                                            */
/* ========================================================================== */

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static struct class *cpld_class;                  //自动创建设备文件时需要先创建类
static struct class_device *cpld_class_dev;       //再创建驱动
static DECLARE_WAIT_QUEUE_HEAD(eint1_waitq);      //将中断放入等待队列
static struct fasync_struct *eint1_async;         //
static volatile int ev_eint1 = 0;                 //中断标志，为1表示中断发生，在中断服务程序里置1
volatile unsigned long *cpld_data = NULL;         //CPLD的物理地址映射的虚拟地址指针  0x08000000
volatile unsigned long *gpfcon = NULL;            //GPF控制寄存器
volatile unsigned long *gpfdat = NULL;            //GPF数据寄存器，0位为使能位

static irqreturn_t eint1_irq(int irq, void *dev_id) //中断服务程序
{
    ev_eint1 = 1;                                   //中断标志位置1
    *gpfdat &= ~(1<<2);                             //进入中断GPF2清0
    wake_up_interruptible(&eint1_waitq);            //唤醒休眠的进程
    kill_fasync (&eint1_async, SIGIO, POLL_IN);     //产生中断后，驱动向应用程序发送信号     
    return IRQ_RETVAL(IRQ_HANDLED);
}

static int cpld_drv_open(struct inode *inode, struct file *file)
{
    request_irq(IRQ_EINT1,  eint1_irq, IRQ_TYPE_EDGE_FALLING, "EINT1", 1);//注册中断：中断号，中断程序入口，中断方式，中断名，代号
    return 0;
}
 
static ssize_t cpld_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
    int val;
    *gpfdat &=~(1<<0);                //使能位置0，使能CPLD产生PWM，计数器开始计数
    copy_from_user(&val, buf, count); //产生PWM的值从用户空间传入
    iowrite16(val,cpld_data);         //写入CPLD
    return 0;
}
 
static ssize_t cpld_drv_read(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
    int val;
    wait_event_interruptible(eint1_waitq, ev_eint1);  //若无中断产生，即ev_eint1=0,则休眠
    val=ioread16(cpld_data);                          //若中断产生，则从CPLD读取数据，即编码器值
    copy_to_user(buf,&val,count);                     //将读取值传递到用户空间
    ev_eint1 = 0;                                     //中断标志清0
    *gpfdat |= (1<<2);                               //中断读数后，GPF2置1
    return 0;
}

static unsigned cpld_drv_poll(struct file *file, poll_table *wait)
{
   unsigned int mask = 0;
   poll_wait(file, &eint1_waitq, wait);       //不会立即休眠
   if (ev_eint1)
   mask |= POLLIN | POLLRDNORM;               //若产生中断，mask赋值，表示有数据可读
   return mask;
}
 
static int cpld_drv_fasync (int fd, struct file *filp, int on)
{
 //printk("driver: cpld_drv_fasync\n");
 return fasync_helper (fd, filp, on, &eint1_async);
}

int cpld_drv_close(struct inode *inode, struct file *file)
{
    free_irq(IRQ_EINT1, 1);       //释放中断  
    return 0;
}
 
static struct file_operations cpld_drv_fops = {
    .owner    = THIS_MODULE,                  
    .write    = cpld_drv_write,
    .read     = cpld_drv_read,
    .open     = cpld_drv_open,
    .release  = cpld_drv_close,
    .poll     = cpld_drv_poll,
    .fasync   = cpld_drv_fasync,  
};
 
int major;
static int cpld_drv_init(void)
{
    major = register_chrdev(0, "cpld_drv", &cpld_drv_fops);                 //注册设备
    cpld_class = class_create(THIS_MODULE, "cplddrv");                      //创建类
    cpld_class_dev = device_create(cpld_class, NULL, MKDEV(major, 0), NULL, "cpld_drv"); //自动创建设备文件 /dev/cpld_drv
    cpld_data = (volatile unsigned long *)ioremap(0x08000000,4);            //映射CPLD物理地址到虚拟地址
    gpfcon = (volatile unsigned long *)ioremap(0x56000050, 8);              //映射GPF寄存器物理地址到虚拟地址
    gpfdat = gpfcon+1;
    *gpfcon &=~((0x3<<0) | (0x3<<(2*2)));
    *gpfcon |=((0x1<<0) | (0x01<<(2*2)));     //设置GPF0、2为输出
    *gpfdat |=0x1;          //将使能位置1，加载驱动时CPLD不输出PWM
    printk("cpld_drv initialized!\n");
    return 0;
}
 
static void cpld_drv_exit(void)
{
    *gpfdat |=0x1;          //将使能位置1，卸载驱动后CPLD不输出PWM
    unregister_chrdev(major, "cpld_drv"); //注销驱动
    device_unregister(cpld_class_dev);    //注销设备
    class_destroy(cpld_class);            //注销类
    iounmap(cpld_data);                   //取消映射
    iounmap(gpfcon);
}
 
module_init(cpld_drv_init);
module_exit(cpld_drv_exit);
 
MODULE_LICENSE("GPL");