leds.c

LED 驱动 写的不错

/*
 * LED driver for Atmel AT91-based boards.
 *
 *  Copyright (C) SAN People (Pty) Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
*/

#include <linux/kernel.h>  /*printk()*/
#include <linux/module.h>  /**/
#include <linux/moduleparam.h>
#include <linux/init.h>

#include <linux/types.h>   /*size_t*/
#include <linux/slab.h>
#include <linux/fs.h>      /*everything...*/
#include <linux/errno.h>   /*error codes*/
#include <linux/uaccess.h> /*copy_*_user*/
#include <linux/cdev.h>
#include <linux/fcntl.h>

#include <asm/mach-types.h>
#include <asm/leds.h>
#include <asm/arch/board.h>
#include <asm/arch/gpio.h>

#include "leds.h"

struct led_dev *led_devices;
int led_major = LED_MAJOR;
int led_minor = 1;
int led_nr_devs = LED_NR_DEVS;

module_param(led_major,int,S_IRUGO);
module_param(led_minor,int,S_IRUGO);
module_param(led_nr_devs,int,S_IRUGO);


static  void at91_led_on(unsigned int led)
{
	at91_set_gpio_value(led, 0);
}

static  void at91_led_off(unsigned int led)
{
	at91_set_gpio_value(led, 1);
}

static  void at91_led_toggle(unsigned int led)
{
	unsigned long is_off = at91_get_gpio_value(led);
	if (is_off)
		at91_led_on(led);
	else
		at91_led_off(led);
}

static int AT91SAM_LED_open(struct inode *inode,struct file *filp)
{
 struct led_dev *dev;
 dev = container_of(inode->i_cdev,struct led_dev,cdev);
 filp->private_data = dev;
 return 0;
}
 
static int AT91SAM_LED_release(struct inode *inode,struct file *filp)
{
 printk("Led release.\n");
 return 0;
}
 
static ssize_t AT91SAM_LED_write(struct file *filp,const char __user *buffer,size_t count,loff_t *f_pos)
{
  at91_led_toggle(AT91_PIN_PB8);
  return 0;
  
}

struct file_operations AT91SAM_LED_fops = {
	.owner   = 	THIS_MODULE,
	.write   =	AT91SAM_LED_write,
	.open    =	AT91SAM_LED_open,
	.release =	AT91SAM_LED_release,
};

static void led_setup_cdev(struct led_dev *dev,int index)
{
	int err,devno = MKDEV(led_major,led_minor+index);
	cdev_init(&dev->cdev,&AT91SAM_LED_fops);
	dev->cdev.owner = THIS_MODULE;
	dev->cdev.ops   = &AT91SAM_LED_fops;
	err = cdev_add(&dev->cdev,devno,1);
	/*Fail gracefully if need be*/
	if(err)
		printk("Error %d adding led%d",err,index);
}

static int __init AT91SAM_LED_init(void)
{
	int result,i;
	dev_t dev = 0;


	if(led_major){
		dev = MKDEV(led_major,led_minor);
		result = register_chrdev_region(dev,led_nr_devs,"LED_DEV");
	}else {
		result = alloc_chrdev_region(&dev,led_minor,led_nr_devs,"LED_DEV");
		led_major = MAJOR(dev);
	}
	if(result<0){
		printk("LED_DEV:Can't get major %d\n",led_major);
		return result;
	}	
	/*allocate the devices --we can't have them static,as the number*/
	led_devices = kmalloc(led_nr_devs*sizeof(struct led_dev),GFP_KERNEL);
	if(led_devices){
		result = -ENOMEM;
		goto fail;  /*Make this more graceful*/	
	memset(led_devices,0,led_nr_devs*sizeof(struct led_dev));
	}
	/*Initialize each device*/
	for(i=0;i<led_nr_devs;i++){
		led_devices[i].led_on =  0;
		led_devices[i].led_off = 0;
		led_setup_cdev(&led_devices[i],i);
	}
	
	
        at91_set_gpio_output(AT91_PIN_PB8,1);
	at91_set_gpio_output(AT91_PIN_PC29,1);
//	leds_event(led_start);
	at91_led_off(AT91_PIN_PC29);
	at91_led_off(AT91_PIN_PB8);
	printk("The led on!\n");
	return 0;
fail:
	return result;
}
static void  __exit AT91SAM_LED_exit(void)
 {
	int i;
	dev_t devno = MKDEV(led_major,led_minor);
	/*Get rid of our char dev entries*/
	if(led_devices){
		for(i=0;i<led_nr_devs;i++);
		cdev_del(&led_devices[i].cdev);
	}
	kfree(led_devices);
	/*cleanup_module if never called if registering failed*/
	unregister_chrdev_region(devno,led_nr_devs);
 
 }

//__initcall(leds_init);
module_init(AT91SAM_LED_init);
module_exit(AT91SAM_LED_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Wenzel Cai");
MODULE_DESCRIPTION("LED driver for Atmel AT91SAM9263");