lkmpg/examples/kbleds.c
linD026 9289bfe59c
Fix the warnings raised by Sparse (#92)
Sparse[1] is a semantic parser, capable of finding out the potential
problems of Linux kernel code. This patch fixed the warnings.

[1] https://www.kernel.org/doc/html/latest/dev-tools/sparse.html
2021-09-04 17:53:29 +08:00

89 lines
2.7 KiB
C

/*
* kbleds.c - Blink keyboard leds until the module is unloaded.
*/
#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 */
#include <linux/console_struct.h> /* For vc_cons */
MODULE_DESCRIPTION("Example module illustrating the use of Keyboard LEDs.");
static struct timer_list my_timer;
static struct tty_driver *my_driver;
static 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:
* drivers/tty/vt/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: drivers/tty/vt/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);
MODULE_LICENSE("GPL");