ds_hw_id.c

#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>

int ds_gpio = 13;
char ds = '0';

int ds_read( char *page, char **start, off_t off, int count, int *eof, void *data )
{
   return sprintf(page, "%c\n", ds );
}

static int __init ds_hw_id_init(void)
{
	int ret = -1;
	printk(KERN_INFO "ds_hw_id_init enter\n");
	
	ret = gpio_request(ds_gpio, "ds");
	if (ret) {
		printk(KERN_INFO "gpio_%d request failed!!!!\n", ds_gpio); 	
	} else if (gpio_get_value(ds_gpio))
		ds = '1';
	gpio_free(ds_gpio);
	
	create_proc_read_entry("ds", 0, NULL, ds_read, NULL);
	
	return 0;
}

static void __exit ds_hw_id_exit(void)
{
	printk(KERN_INFO "ds_hw_id_exit enter\n");
}

module_init(ds_hw_id_init);
module_exit(ds_hw_id_exit);