Linux下CPLD驱动程序

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

#include linux/device.h>
#include linux/module.h>
#include linux/kernel.h>
#include linux/fs.h>
#include linux/init.h>
#include linux/delay.h>
#include asm/uaccess.h>
#include linux/types.h>
#include linux/errno.h>
#include linux/mm.h>
#include linux/sched.h>
#include linux/cdev.h>
#include linux/kdev_t.h>
#include asm/system.h>
#include linux/poll.h>
#include linux/irq.h>
#include asm/irq.h>
#include asm/io.h>
#include linux/interrupt.h>
#include mach/regs-gpio.h>
#include mach/hardware.h>
#include linux/gpio.h>

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 = ~(12); //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 =~(10); //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 |= (12); //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_fasyncn);
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 =~((0x30) | (0x3(2*2)));
*gpfcon |=((0x10) | (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);