Add new file

gassensor.c

+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+
+#include <asm/mach/map.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+#define GAS_GPIO 23 //GPIO 23 
+#define GAS_MAJOR_NUMBER	505
+#define GAS_DEV_NAME 	"gas_ioctl"
+
+//GPIO 23
+#define GPIO_BASE_ADDR 0x3F200000
+#define GPFSEL2 0x08
+#define GPSET0 0x1C
+#define GPCLR0 0x28
+
+#define IOCTL_MAGIC_NUMBER		'g'
+#define IOCTL_CMD_GAS_ON					_IO(IOCTL_MAGIC_NUMBER, 0)
+#define IOCTL_CMD_GAS_OFF					_IO(IOCTL_MAGIC_NUMBER, 1)
+
+#define HIGH 1
+#define LOW 0
+
+static void __iomem *gpio_base;
+volatile unsigned int *gpsel2;
+volatile unsigned int *gpset1;
+volatile unsigned int *gpclr1;
+
+int gas_open(struct inode *inode, struct file *flip) {
+
+	printk(KERN_ALERT "gas driver open!!\n");
+
+	gpio_base = ioremap(GPIO_BASE_ADDR, 0x60);
+	gpsel2 = (volatile unsigned int *)(gpio_base + GPFSEL2);
+	gpset1 = (volatile unsigned int *)(gpio_base + GPSET0);
+	gpclr1 = (volatile unsigned int *)(gpio_base + GPCLR0);
+
+	gpio_request(GAS_GPIO, "GAS_GPIO");
+	//set direction in
+	*gpsel2 |= (0 << 9);
+
+
+	return 0;
+}
+
+int gas_release(struct inode *inode, struct file *filp) {
+	printk(KERN_ALERT "gas driver closed!!\n");
+	iounmap((void *)gpio_base);
+	return 0;
+}
+
+long gas_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+
+	switch (cmd) {
+	case IOCTL_CMD_GAS_ON:
+		printk(KERN_ALERT "GAS detecting start!!\n");
+		while (1) {
+			int i = gpio_get_value(GAS_GPIO);
+			if (i == HIGH) {
+				return HIGH;
+			}
+			else
+				return LOW;
+		}
+		ssleep(3);
+
+	case IOCTL_CMD_GAS_OFF:
+		printk(KERN_ALERT "GAS off!!\n");
+		*gpsel2 |= (1 << 9);
+		break;
+	}
+	return 0;
+}
+
+static struct file_operations gas_fops = {
+	.owner = THIS_MODULE,
+	.open = gas_open,
+	.release = gas_release,
+	.unlocked_ioctl = gas_ioctl
+};
+
+int __init gas_init(void) {
+	if (register_chrdev(GAS_MAJOR_NUMBER, GAS_DEV_NAME, &gas_fops) < 0)
+		printk(KERN_ALERT "gas driver initialization fail\n");
+	else
+		printk(KERN_ALERT "gas driver initailization success\n");
+
+	return 0;
+}
+
+void __exit gas_exit(void) {
+	unregister_chrdev(GAS_MAJOR_NUMBER, GAS_DEV_NAME);
+	printk(KERN_ALERT "GAS driver exit done\n");
+}
+
+module_init(gas_init);
+module_exit(gas_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("sang");
+MODULE_DESCRIPTION("des");