lkmpg/examples/vkbd.c

#include <linux/init.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/spinlock.h>

#include "vinput.h"

#define VINPUT_KBD "vkbd"
#define VINPUT_RELEASE 0
#define VINPUT_PRESS 1

static unsigned short vkeymap[KEY_MAX];

static int vinput_vkbd_init(struct vinput *vinput)
{
    int i;

    /* Set up the input bitfield */
    vinput->input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
    vinput->input->keycodesize = sizeof(unsigned short);
    vinput->input->keycodemax = KEY_MAX;
    vinput->input->keycode = vkeymap;

    for (i = 0; i < KEY_MAX; i++)
        set_bit(vkeymap[i], vinput->input->keybit);

    /* vinput will help us allocate new input device structure via
     * input_allocate_device(). So, we can register it straightforwardly.
     */
    return input_register_device(vinput->input);
}

static int vinput_vkbd_read(struct vinput *vinput, char *buff, int len)
{
    spin_lock(&vinput->lock);
    len = snprintf(buff, len, "%+ld\n", vinput->last_entry);
    spin_unlock(&vinput->lock);

    return len;
}

static int vinput_vkbd_send(struct vinput *vinput, char *buff, int len)
{
    int ret;
    long key = 0;
    short type = VINPUT_PRESS;

    /* Determine which event was received (press or release)
     * and store the state.
     */
    if (buff[0] == '+')
        ret = kstrtol(buff + 1, 10, &key);
    else
        ret = kstrtol(buff, 10, &key);
    if (ret)
        dev_err(&vinput->dev, "error during kstrtol: -%d\n", ret);
    spin_lock(&vinput->lock);
    vinput->last_entry = key;
    spin_unlock(&vinput->lock);

    if (key < 0) {
        type = VINPUT_RELEASE;
        key = -key;
    }

    dev_info(&vinput->dev, "Event %s code %ld\n",
             (type == VINPUT_RELEASE) ? "VINPUT_RELEASE" : "VINPUT_PRESS", key);

    /* Report the state received to input subsystem. */
    input_report_key(vinput->input, key, type);
    /* Tell input subsystem that it finished the report. */
    input_sync(vinput->input);

    return len;
}

static struct vinput_ops vkbd_ops = {
    .init = vinput_vkbd_init,
    .send = vinput_vkbd_send,
    .read = vinput_vkbd_read,
};

static struct vinput_device vkbd_dev = {
    .name = VINPUT_KBD,
    .ops = &vkbd_ops,
};

static int __init vkbd_init(void)
{
    int i;

    for (i = 0; i < KEY_MAX; i++)
        vkeymap[i] = i;
    return vinput_register(&vkbd_dev);
}

static void __exit vkbd_end(void)
{
    vinput_unregister(&vkbd_dev);
}

module_init(vkbd_init);
module_exit(vkbd_end);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Emulate keyboard input events through /dev/vinput");