nhmk/examples/kbleds.c

/*
 *  kbleds.c - Blink keyboard leds until the module is unloaded.
 */

#include <linux/console_struct.h> /* For vc_cons */
#include <linux/init.h>
#include <linux/kd.h> /* For KDSETLED */
#include <linux/module.h>
#include <linux/tty.h> /* For fg_console, MAX_NR_CONSOLES */
#include <linux/vt.h>
#include <linux/vt_kern.h> /* for fg_console */

MODULE_DESCRIPTION("Example module illustrating the use of Keyboard LEDs.");
MODULE_AUTHOR("Daniele Paolo Scarpazza");
MODULE_LICENSE("GPL");

struct timer_list my_timer;
struct tty_driver *my_driver;
char kbledstatus = 0;

#define BLINK_DELAY HZ / 5
#define ALL_LEDS_ON 0x07
#define RESTORE_LEDS 0xFF

/*
 * Function my_timer_func blinks the keyboard LEDs periodically by invoking
 * command KDSETLED of ioctl() on the keyboard driver. To learn more on virtual
 * terminal ioctl operations, please see file:
 *     /usr/src/linux/drivers/char/vt_ioctl.c, function vt_ioctl().
 *
 * The argument to KDSETLED is alternatively set to 7 (thus causing the led
 * mode to be set to LED_SHOW_IOCTL, and all the leds are lit) and to 0xFF
 * (any value above 7 switches back the led mode to LED_SHOW_FLAGS, thus
 * the LEDs reflect the actual keyboard status).  To learn more on this,
 * please see file:
 *     /usr/src/linux/drivers/char/keyboard.c, function setledstate().
 *
 */

static void my_timer_func(unsigned long ptr)
{
    unsigned long *pstatus = (unsigned long *) ptr;
    struct tty_struct *t = vc_cons[fg_console].d->port.tty;

    if (*pstatus == ALL_LEDS_ON)
        *pstatus = RESTORE_LEDS;
    else
        *pstatus = ALL_LEDS_ON;

    (my_driver->ops->ioctl)(t, KDSETLED, *pstatus);

    my_timer.expires = jiffies + BLINK_DELAY;
    add_timer(&my_timer);
}

static int __init kbleds_init(void)
{
    int i;

    pr_info("kbleds: loading\n");
    pr_info("kbleds: fgconsole is %x\n", fg_console);
    for (i = 0; i < MAX_NR_CONSOLES; i++) {
        if (!vc_cons[i].d)
            break;
        pr_info("poet_atkm: console[%i/%i] #%i, tty %lx\n", i, MAX_NR_CONSOLES,
                vc_cons[i].d->vc_num, (unsigned long) vc_cons[i].d->port.tty);
    }
    pr_info("kbleds: finished scanning consoles\n");

    my_driver = vc_cons[fg_console].d->port.tty->driver;
    pr_info("kbleds: tty driver magic %x\n", my_driver->magic);

    /*
     * Set up the LED blink timer the first time
     */
    timer_setup(&my_timer, (void *) &my_timer_func,
                (unsigned long) &kbledstatus);
    my_timer.expires = jiffies + BLINK_DELAY;
    add_timer(&my_timer);

    return 0;
}

static void __exit kbleds_cleanup(void)
{
    pr_info("kbleds: unloading...\n");
    del_timer(&my_timer);
    (my_driver->ops->ioctl)(vc_cons[fg_console].d->port.tty, KDSETLED,
                            RESTORE_LEDS);
}

module_init(kbleds_init);
module_exit(kbleds_cleanup);