Linux Device Driver to disable/enable keyboard

Theory:

As we have seen in our earlier posts, that there are three registers for keyboard controller.

• Control Register (0x64) -- Write Operation
• Data Register (0x60) -- Write/Read Operation
• Status Register (0x60) -- Read Operation

Process to disable Keyboard:

• Wait until the keyboard controller is not busy by reading the status register
• Send the command 0xAD to Control Register

Process to Enable Keyboard:

• Wait until the keyboard controller is not busy by reading the status register
• Send the command 0xAE to Control Register.

Code:

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	MODULE_LICENSE("GPL");
	int sleep_duration = 10000;
	module_param(sleep_duration, int, S_IRUGO);
	#define KBD_DATA_REG 0x60 /* I/O port for keyboard data */
	#define KBD_CONTROL_REG 0x64
	#define DELAY do { mdelay(1); if (++delay > 10) break; } while(0)
	static void disable_keyboard(void)
	{
	long delay = 0;
	//wait till the input buffer is empty
	while (inb(KBD_CONTROL_REG) & 0x02)
	DELAY;
	outb(0xAD, KBD_CONTROL_REG);
	}
	static void enable_keyboard(void)
	{
	long delay = 0;
	//wait till the input buffer is empty
	while (inb(KBD_CONTROL_REG) & 0x02)
	DELAY;
	outb(0xAE, KBD_CONTROL_REG);
	}
	static int test_kbd_disable_init(void)
	{
	pr_info("%s: In init\n", __func__);
	disable_keyboard();
	msleep(sleep_duration);
	enable_keyboard();
	return 0;
	}
	static void test_kbd_disable_exit(void)
	{
	pr_info("%s: In exit\n", __func__);
	}
	module_init(test_kbd_disable_init);
	module_exit(test_kbd_disable_exit);

view raw kbd_disable.c hosted with ❤ by GitHub

Output:

Notes:

We have loaded the module using the command "sleep 1 && insmod ./kbd_disable.ko". If you try only "insmod ./kbd_disable.ko", the keyboard will disable at "Enter Press", so the console will be continuously receiving Enter Press Keys, until keyboard gets enabled back