led_driver.c

对初级编写驱动代码有非常大的帮助,这是基与 S3C2410的LED_DRIVER, 初学者非常容易看完之后掌握

#include <linux/config.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
//Please configure your kernel first to use the following headers, because the directory "asm" is a short cut to your arch's "asm" directory.
//So do the headers in the "hardware" sub directory.
#include <asm/io.h>  //This header is for ioremap(), iounmap().
#include <asm/uaccess.h>  //This header is for get_user(), put_user().
#define NAME "led_test"
MODULE_AUTHOR("Lu Xianzi <[e-mail]>");  //This line and the following 4 lines can be omitted.
MODULE_DESCRIPTION("LED Test Driver");
MODULE_LICENSE("GPL");
//module_param(major, int, 0);
MODULE_PARM_DESC(major, "Major device number");

static int major = 231;  //Define device major
module_param( major, int, 0 );
unsigned long * pREG;  //Definition of register base.

static ssize_t led_test_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
{
	char buf[256];
	size_t i;
	for (i = 0; i < len && i < 254; i++)
		if (get_user(buf[i], data + i))
			return -EFAULT;

	buf[i] = '\0';
	printk("LED Test - write: user_data %s\n", buf);
	return (len < 255 ? len : 255);
}
static ssize_t led_test_read(struct file *file, char __user *buf, size_t len, loff_t *ppos)
{
	char rbuf[4];
	size_t i;
	long tmp;

	tmp = * (volatile unsigned long *)(pREG + 1);
	rbuf[0] = tmp % 256;
	rbuf[1] = (tmp >> 8) % 256;
	rbuf[2] = (tmp >> 16) % 256;
	rbuf[3] = (tmp >> 24) % 256;

	if (len > 4)
		return 0;
	for (i = 0; i < len && i < 4; i++)
		if (put_user(rbuf[i], buf + i))
			return -EFAULT;
	printk("LED Test - read\n");
	return (len < 4 ? len : 4);
}
static int led_test_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	unsigned long tmp;
	printk("LED Test - ioctl: param %u %lu\n", cmd, arg);
	switch (cmd)
	{
		case 0:
		case 1:
			if (arg > 3)
				return -EINVAL;
			if (!cmd)
				* (volatile unsigned long *)(pREG + 1) |= (0x80 << arg);
			else
				* (volatile unsigned long *)(pREG + 1) &= ~(0x80 << arg);
			tmp = * (volatile unsigned long *)pREG;
			printk("GPBCON = 0x%lx\n", tmp);
			tmp = * (volatile unsigned long *)(pREG + 1);
			printk("GPBDAT = 0x%lx\n", tmp);
			break;
		default:
			return -EINVAL;
	}
	return 1;
}
static int led_test_open(struct inode *inode, struct file *file)
{
	unsigned m = iminor(inode);
	if (m > 63)
		return -EINVAL;
	printk("LED Test driver opened!\n");
	return nonseekable_open(inode, file);
}
static int led_test_release(struct inode *inode, struct file *file)
{
	printk("LED Test driver released!\n");
	return 0;
}

static struct file_operations led_test_fops = {
	.owner   = THIS_MODULE,
	.ioctl   = led_test_ioctl,
	.write   = led_test_write,
	.read    = led_test_read,
	.open    = led_test_open,
	.release = led_test_release,
};
static int __init led_test_init(void)
{
	int ret;
	unsigned long tmp;

	printk("LXZ LED Test Driver.\n");
	ret = register_chrdev(major, NAME, &led_test_fops);
	if (ret < 0) {
		printk("Unable to register character device!\n");
		return ret;
	}
	pREG = ioremap(0x56000010, 0x20);
	printk("Virtual addr base = 0x%lx\n", (unsigned long)pREG);
	tmp = * (volatile unsigned long *)pREG;
	printk("GPBCON = 0x%lx\n", tmp);
	tmp = * (volatile unsigned long *)(pREG + 1);
	printk("GPBDAT = 0x%lx\n", tmp);
	printk("Seting LED Test Driver...\n"); 
	* (volatile unsigned long *)pREG = 0x155555;
	* (volatile unsigned long *)(pREG + 1) = 0xfff;
	tmp = * (volatile unsigned long *)pREG;
	printk("GPBCON = 0x%lx\n", tmp);
	tmp = * (volatile unsigned long *)(pREG + 1);
	printk("GPBDAT = 0x%lx\n", tmp);

	* (volatile unsigned long *)pREG = 0x15555A;
	tmp = * (volatile unsigned long *)pREG;
	printk("GPBCON = 0x%lx\n", tmp);
	* (volatile unsigned long *)pREG = 0x155552;
	tmp = * (volatile unsigned long *)pREG;
	printk("GPBCON = 0x%lx\n", tmp);
	printk("LED Test Driver initiated.\n"); 
	return 0;
}
static void __exit led_test_cleanup(void)
{
	int ret;

	iounmap(pREG);

	ret = unregister_chrdev(major, NAME); 
	if (ret < 0)
		printk("Unable to register character device!\n");
	else
		printk("LED Test Driver unloaded!");
}
module_init(led_test_init);
module_exit(led_test_cleanup);