source: mainline/uspace/drv/usbhid/kbddev.c@ dfe53af

/*
 * Copyright (c) 2011 Lubos Slovak
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup drvusbhid
 * @{
 */
/**
 * @file
 * USB HID keyboard device structure and API.
 */

#include <errno.h>
#include <str_error.h>
#include <stdio.h>

#include <io/keycode.h>
#include <ipc/kbd.h>
#include <async.h>
#include <fibril.h>
#include <fibril_synch.h>

#include <usb/usb.h>
#include <usb/classes/hid.h>
#include <usb/pipes.h>
#include <usb/debug.h>
#include <usb/classes/hidparser.h>
#include <usb/classes/classes.h>

#include "kbddev.h"
#include "hiddev.h"
#include "hidreq.h"
#include "layout.h"
#include "conv.h"
#include "kbdrepeat.h"

/*----------------------------------------------------------------------------*/

static const unsigned DEFAULT_ACTIVE_MODS = KM_NUM_LOCK;
static const size_t BOOTP_REPORT_SIZE = 6;
static const size_t BOOTP_BUFFER_SIZE = 8;
static const size_t BOOTP_BUFFER_OUT_SIZE = 1;
static const uint8_t BOOTP_ERROR_ROLLOVER = 1;
static const uint8_t IDLE_RATE = 0;
static const unsigned int DEFAULT_DELAY_BEFORE_FIRST_REPEAT = 500 * 1000;
static const unsigned int DEFAULT_REPEAT_DELAY = 50 * 1000;

/** Keyboard polling endpoint description for boot protocol class. */
static usb_endpoint_description_t poll_endpoint_description = {
        .transfer_type = USB_TRANSFER_INTERRUPT,
        .direction = USB_DIRECTION_IN,
        .interface_class = USB_CLASS_HID,
        .interface_subclass = USB_HID_SUBCLASS_BOOT,
        .interface_protocol = USB_HID_PROTOCOL_KEYBOARD,
        .flags = 0
};

/*----------------------------------------------------------------------------*/
/* Keyboard layouts                                                           */
/*----------------------------------------------------------------------------*/

#define NUM_LAYOUTS 3

static layout_op_t *layout[NUM_LAYOUTS] = {
        &us_qwerty_op,
        &us_dvorak_op,
        &cz_op
};

static int active_layout = 0;

/*----------------------------------------------------------------------------*/
/* Modifier constants                                                         */
/*----------------------------------------------------------------------------*/

static const keycode_t usbhid_modifiers_keycodes[USB_HID_MOD_COUNT] = {
        KC_LCTRL,         /* USB_HID_MOD_LCTRL */
        KC_LSHIFT,        /* USB_HID_MOD_LSHIFT */
        KC_LALT,          /* USB_HID_MOD_LALT */
        0,                /* USB_HID_MOD_LGUI */
        KC_RCTRL,         /* USB_HID_MOD_RCTRL */
        KC_RSHIFT,        /* USB_HID_MOD_RSHIFT */
        KC_RALT,          /* USB_HID_MOD_RALT */
        0,                /* USB_HID_MOD_RGUI */
};

/*----------------------------------------------------------------------------*/
/* IPC method handler                                                         */
/*----------------------------------------------------------------------------*/

static void default_connection_handler(ddf_fun_t *, ipc_callid_t, ipc_call_t *);
static ddf_dev_ops_t keyboard_ops = {
        .default_handler = default_connection_handler
};

/** Default handler for IPC methods not handled by DDF.
 *
 * @param dev Device handling the call.
 * @param icallid Call id.
 * @param icall Call data.
 */
void default_connection_handler(ddf_fun_t *fun,
    ipc_callid_t icallid, ipc_call_t *icall)
{
        sysarg_t method = IPC_GET_IMETHOD(*icall);
        
        usbhid_kbd_t *kbd_dev = (usbhid_kbd_t *)fun->driver_data;
        assert(kbd_dev != NULL);

        if (method == IPC_M_CONNECT_TO_ME) {
                int callback = IPC_GET_ARG5(*icall);

                if (kbd_dev->console_phone != -1) {
                        async_answer_0(icallid, ELIMIT);
                        return;
                }

                kbd_dev->console_phone = callback;
                async_answer_0(icallid, EOK);
                return;
        }
        
        async_answer_0(icallid, EINVAL);
}

/*----------------------------------------------------------------------------*/
/* Key processing functions                                                   */
/*----------------------------------------------------------------------------*/

static void usbhid_kbd_set_led(usbhid_kbd_t *kbd_dev) 
{
        uint8_t buffer[BOOTP_BUFFER_OUT_SIZE];
        int rc= 0;
        
        memset(buffer, 0, BOOTP_BUFFER_OUT_SIZE);
        uint8_t leds = 0;

        if (kbd_dev->mods & KM_NUM_LOCK) {
                leds |= USB_HID_LED_NUM_LOCK;
        }
        
        if (kbd_dev->mods & KM_CAPS_LOCK) {
                leds |= USB_HID_LED_CAPS_LOCK;
        }
        
        if (kbd_dev->mods & KM_SCROLL_LOCK) {
                leds |= USB_HID_LED_SCROLL_LOCK;
        }

        // TODO: COMPOSE and KANA
        
        usb_log_debug("Creating output report.\n");
        usb_log_debug("Leds: 0x%x\n", leds);
        if ((rc = usb_hid_boot_keyboard_output_report(
            leds, buffer, BOOTP_BUFFER_OUT_SIZE)) != EOK) {
                usb_log_warning("Error composing output report to the keyboard:"
                    "%s.\n", str_error(rc));
                return;
        }
        
        usb_log_debug("Output report buffer: %s\n", 
            usb_debug_str_buffer(buffer, BOOTP_BUFFER_OUT_SIZE, 0));
        
        assert(kbd_dev->hid_dev != NULL);
        assert(kbd_dev->hid_dev->initialized);
        usbhid_req_set_report(kbd_dev->hid_dev, USB_HID_REPORT_TYPE_OUTPUT, 
            buffer, BOOTP_BUFFER_OUT_SIZE);
}

/*----------------------------------------------------------------------------*/

void usbhid_kbd_push_ev(usbhid_kbd_t *kbd_dev, int type, unsigned int key)
{
        console_event_t ev;
        unsigned mod_mask;

        /*
         * These parts are copy-pasted from the AT keyboard driver.
         *
         * They definitely require some refactoring, but will keep it for later
         * when the console and keyboard system is changed in HelenOS.
         */
        switch (key) {
        case KC_LCTRL: mod_mask = KM_LCTRL; break;
        case KC_RCTRL: mod_mask = KM_RCTRL; break;
        case KC_LSHIFT: mod_mask = KM_LSHIFT; break;
        case KC_RSHIFT: mod_mask = KM_RSHIFT; break;
        case KC_LALT: mod_mask = KM_LALT; break;
        case KC_RALT: mod_mask = KM_RALT; break;
        default: mod_mask = 0; break;
        }

        if (mod_mask != 0) {
                if (type == KEY_PRESS)
                        kbd_dev->mods = kbd_dev->mods | mod_mask;
                else
                        kbd_dev->mods = kbd_dev->mods & ~mod_mask;
        }

        switch (key) {
        case KC_CAPS_LOCK: mod_mask = KM_CAPS_LOCK; break;
        case KC_NUM_LOCK: mod_mask = KM_NUM_LOCK; break;
        case KC_SCROLL_LOCK: mod_mask = KM_SCROLL_LOCK; break;
        default: mod_mask = 0; break;
        }

        if (mod_mask != 0) {
                if (type == KEY_PRESS) {
                        /*
                         * Only change lock state on transition from released
                         * to pressed. This prevents autorepeat from messing
                         * up the lock state.
                         */
                        unsigned int locks_old = kbd_dev->lock_keys;
                        
                        kbd_dev->mods = 
                            kbd_dev->mods ^ (mod_mask & ~kbd_dev->lock_keys);
                        kbd_dev->lock_keys = kbd_dev->lock_keys | mod_mask;

                        /* Update keyboard lock indicator lights. */
                        if (kbd_dev->lock_keys != locks_old) {
                                usbhid_kbd_set_led(kbd_dev);
                        }
                } else {
                        kbd_dev->lock_keys = kbd_dev->lock_keys & ~mod_mask;
                }
        }

        if (key == KC_CAPS_LOCK || key == KC_NUM_LOCK || key == KC_SCROLL_LOCK) {
                // do not send anything to the console, this is our business
                return;
        }
        
        if (type == KEY_PRESS && (kbd_dev->mods & KM_LCTRL) && key == KC_F1) {
                active_layout = 0;
                layout[active_layout]->reset();
                return;
        }

        if (type == KEY_PRESS && (kbd_dev->mods & KM_LCTRL) && key == KC_F2) {
                active_layout = 1;
                layout[active_layout]->reset();
                return;
        }

        if (type == KEY_PRESS && (kbd_dev->mods & KM_LCTRL) && key == KC_F3) {
                active_layout = 2;
                layout[active_layout]->reset();
                return;
        }
        
        ev.type = type;
        ev.key = key;
        ev.mods = kbd_dev->mods;

        ev.c = layout[active_layout]->parse_ev(&ev);

        usb_log_debug2("Sending key %d to the console\n", ev.key);
        if (kbd_dev->console_phone < 0) {
                usb_log_warning(
                    "Connection to console not ready, key discarded.\n");
                return;
        }
        
        async_msg_4(kbd_dev->console_phone, KBD_EVENT, ev.type, ev.key, 
            ev.mods, ev.c);
}

/*----------------------------------------------------------------------------*/

static void usbhid_kbd_check_modifier_changes(usbhid_kbd_t *kbd_dev,
    uint8_t modifiers)
{
        /*
         * TODO: why the USB keyboard has NUM_, SCROLL_ and CAPS_LOCK
         *       both as modifiers and as keys with their own scancodes???
         *
         * modifiers should be sent as normal keys to usbhid_parse_scancode()!!
         * so maybe it would be better if I received it from report parser in 
         * that way
         */
        
        int i;
        for (i = 0; i < USB_HID_MOD_COUNT; ++i) {
                if ((modifiers & usb_hid_modifiers_consts[i]) &&
                    !(kbd_dev->modifiers & usb_hid_modifiers_consts[i])) {
                        // modifier pressed
                        if (usbhid_modifiers_keycodes[i] != 0) {
                                usbhid_kbd_push_ev(kbd_dev, KEY_PRESS, 
                                    usbhid_modifiers_keycodes[i]);
                        }
                } else if (!(modifiers & usb_hid_modifiers_consts[i]) &&
                    (kbd_dev->modifiers & usb_hid_modifiers_consts[i])) {
                        // modifier released
                        if (usbhid_modifiers_keycodes[i] != 0) {
                                usbhid_kbd_push_ev(kbd_dev, KEY_RELEASE, 
                                    usbhid_modifiers_keycodes[i]);
                        }
                }       // no change
        }
        
        kbd_dev->modifiers = modifiers;
}

/*----------------------------------------------------------------------------*/

static void usbhid_kbd_check_key_changes(usbhid_kbd_t *kbd_dev, 
    const uint8_t *key_codes)
{
        unsigned int key;
        unsigned int i, j;
        
        /*
         * First of all, check if the kbd have reported phantom state.
         */
        i = 0;
        // all fields should report Error Rollover
        while (i < kbd_dev->key_count &&
            key_codes[i] == BOOTP_ERROR_ROLLOVER) {
                ++i;
        }
        if (i == kbd_dev->key_count) {
                usb_log_debug("Phantom state occured.\n");
                // phantom state, do nothing
                return;
        }
        
        // TODO: quite dummy right now, think of better implementation
        
        /*
         * 1) Key releases
         */
        for (j = 0; j < kbd_dev->key_count; ++j) {
                // try to find the old key in the new key list
                i = 0;
                while (i < kbd_dev->key_count
                    && key_codes[i] != kbd_dev->keys[j]) {
                        ++i;
                }
                
                if (i == kbd_dev->key_count) {
                        // not found, i.e. the key was released
                        key = usbhid_parse_scancode(kbd_dev->keys[j]);
                        usbhid_kbd_repeat_stop(kbd_dev, key);
                        usbhid_kbd_push_ev(kbd_dev, KEY_RELEASE, key);
                        usb_log_debug2("Key released: %d\n", key);
                } else {
                        // found, nothing happens
                }
        }
        
        /*
         * 1) Key presses
         */
        for (i = 0; i < kbd_dev->key_count; ++i) {
                // try to find the new key in the old key list
                j = 0;
                while (j < kbd_dev->key_count 
                    && kbd_dev->keys[j] != key_codes[i]) { 
                        ++j;
                }
                
                if (j == kbd_dev->key_count) {
                        // not found, i.e. new key pressed
                        key = usbhid_parse_scancode(key_codes[i]);
                        usb_log_debug2("Key pressed: %d (keycode: %d)\n", key,
                            key_codes[i]);
                        usbhid_kbd_push_ev(kbd_dev, KEY_PRESS, key);
                        usbhid_kbd_repeat_start(kbd_dev, key);
                } else {
                        // found, nothing happens
                }
        }
//      // report all currently pressed keys
//      for (i = 0; i < kbd_dev->keycode_count; ++i) {
//              if (key_codes[i] != 0) {
//                      key = usbhid_parse_scancode(key_codes[i]);
//                      usb_log_debug2("Key pressed: %d (keycode: %d)\n", key,
//                          key_codes[i]);
//                      usbhid_kbd_push_ev(kbd_dev, KEY_PRESS, key);
//              }
//      }
        
        memcpy(kbd_dev->keys, key_codes, kbd_dev->key_count);

        usb_log_debug("New stored keycodes: %s\n", 
            usb_debug_str_buffer(kbd_dev->keys, kbd_dev->key_count, 0));
}

/*----------------------------------------------------------------------------*/
/* Callbacks for parser                                                       */
/*----------------------------------------------------------------------------*/

static void usbhid_kbd_process_keycodes(const uint8_t *key_codes, size_t count,
    uint8_t modifiers, void *arg)
{
        if (arg == NULL) {
                usb_log_warning("Missing argument in callback "
                    "usbhid_process_keycodes().\n");
                return;
        }
        
        usbhid_kbd_t *kbd_dev = (usbhid_kbd_t *)arg;
        assert(kbd_dev != NULL);

        usb_log_debug("Got keys from parser: %s\n", 
            usb_debug_str_buffer(key_codes, kbd_dev->key_count, 0));
        
        if (count != kbd_dev->key_count) {
                usb_log_warning("Number of received keycodes (%d) differs from"
                    " expected number (%d).\n", count, kbd_dev->key_count);
                return;
        }
        
        usbhid_kbd_check_modifier_changes(kbd_dev, modifiers);
        usbhid_kbd_check_key_changes(kbd_dev, key_codes);
}

/*----------------------------------------------------------------------------*/
/* General kbd functions                                                      */
/*----------------------------------------------------------------------------*/
/**
 * Processes data received from the device in form of report.
 *
 * This function uses the HID report parser to translate the data received from
 * the device into generic USB HID key codes and into generic modifiers bitmap.
 * The parser then calls the given callback (usbhid_kbd_process_keycodes()).
 *
 * @note Currently, only the boot protocol is supported.
 *
 * @param kbd_dev Keyboard device structure (must be initialized).
 * @param buffer Data from the keyboard (i.e. the report).
 * @param actual_size Size of the data from keyboard (report size) in bytes.
 *
 * @sa usbhid_kbd_process_keycodes(), usb_hid_boot_keyboard_input_report().
 */
static void usbhid_kbd_process_data(usbhid_kbd_t *kbd_dev,
                                    uint8_t *buffer, size_t actual_size)
{
        usb_hid_report_in_callbacks_t *callbacks =
            (usb_hid_report_in_callbacks_t *)malloc(
                sizeof(usb_hid_report_in_callbacks_t));
        
        callbacks->keyboard = usbhid_kbd_process_keycodes;

        usb_log_debug("Calling usb_hid_boot_keyboard_input_report() with "
            "buffer %s\n", usb_debug_str_buffer(buffer, actual_size, 0));
        
        int rc = usb_hid_boot_keyboard_input_report(buffer, actual_size,
            callbacks, kbd_dev);
        
        if (rc != EOK) {
                usb_log_warning("Error in usb_hid_boot_keyboard_input_report():"
                    "%s\n", str_error(rc));
        }
}

/*----------------------------------------------------------------------------*/
/* HID/KBD structure manipulation                                             */
/*----------------------------------------------------------------------------*/
/**
 * Creates a new USB/HID keyboard structure.
 *
 * The structure returned by this function is not initialized. Use 
 * usbhid_kbd_init() to initialize it prior to polling.
 *
 * @return New uninitialized structure for representing a USB/HID keyboard or
 *         NULL if not successful (memory error).
 */
static usbhid_kbd_t *usbhid_kbd_new(void)
{
        usbhid_kbd_t *kbd_dev = 
            (usbhid_kbd_t *)malloc(sizeof(usbhid_kbd_t));

        if (kbd_dev == NULL) {
                usb_log_fatal("No memory!\n");
                return NULL;
        }
        
        memset(kbd_dev, 0, sizeof(usbhid_kbd_t));
        
        kbd_dev->hid_dev = usbhid_dev_new();
        if (kbd_dev->hid_dev == NULL) {
                usb_log_fatal("Could not create HID device structure.\n");
                return NULL;
        }
        
        kbd_dev->console_phone = -1;
        kbd_dev->initialized = 0;
        
        return kbd_dev;
}

/*----------------------------------------------------------------------------*/
/**
 * Properly destroys the USB/HID keyboard structure.
 *
 * @param kbd_dev Pointer to the structure to be destroyed.
 */
static void usbhid_kbd_free(usbhid_kbd_t **kbd_dev)
{
        if (kbd_dev == NULL || *kbd_dev == NULL) {
                return;
        }
        
        // hangup phone to the console
        async_hangup((*kbd_dev)->console_phone);
        
        if ((*kbd_dev)->hid_dev != NULL) {
                usbhid_dev_free(&(*kbd_dev)->hid_dev);
                assert((*kbd_dev)->hid_dev == NULL);
        }
        
        if ((*kbd_dev)->repeat_mtx != NULL) {
                /* TODO: replace by some check and wait */
                assert(!fibril_mutex_is_locked((*kbd_dev)->repeat_mtx));
                free((*kbd_dev)->repeat_mtx);
        }
        
        free(*kbd_dev);
        *kbd_dev = NULL;
}

/*----------------------------------------------------------------------------*/
/**
 * Initialization of the USB/HID keyboard structure.
 *
 * This functions initializes required structures from the device's descriptors.
 *
 * During initialization, the keyboard is switched into boot protocol, the idle
 * rate is set to 0 (infinity), resulting in the keyboard only reporting event
 * when a key is pressed or released. Finally, the LED lights are turned on 
 * according to the default setup of lock keys.
 *
 * @note By default, the keyboards is initialized with Num Lock turned on and 
 *       other locks turned off.
 *
 * @param kbd_dev Keyboard device structure to be initialized.
 * @param dev DDF device structure of the keyboard.
 *
 * @retval EOK if successful.
 * @retval EINVAL if some parameter is not given.
 * @return Other value inherited from function usbhid_dev_init().
 */
static int usbhid_kbd_init(usbhid_kbd_t *kbd_dev, ddf_dev_t *dev)
{
        int rc;
        
        usb_log_info("Initializing HID/KBD structure...\n");
        
        if (kbd_dev == NULL) {
                usb_log_error("Failed to init keyboard structure: no structure"
                    " given.\n");
                return EINVAL;
        }
        
        if (dev == NULL) {
                usb_log_error("Failed to init keyboard structure: no device"
                    " given.\n");
                return EINVAL;
        }
        
        if (kbd_dev->initialized) {
                usb_log_warning("Keyboard structure already initialized.\n");
                return EINVAL;
        }
        
        rc = usbhid_dev_init(kbd_dev->hid_dev, dev, &poll_endpoint_description);
        
        if (rc != EOK) {
                usb_log_error("Failed to initialize HID device structure: %s\n",
                   str_error(rc));
                return rc;
        }
        
        assert(kbd_dev->hid_dev->initialized);
        
        // save the size of the report (boot protocol report by default)
        kbd_dev->key_count = BOOTP_REPORT_SIZE;
        kbd_dev->keys = (uint8_t *)calloc(
            kbd_dev->key_count, sizeof(uint8_t));
        
        if (kbd_dev->keys == NULL) {
                usb_log_fatal("No memory!\n");
                return ENOMEM;
        }
        
        kbd_dev->modifiers = 0;
        kbd_dev->mods = DEFAULT_ACTIVE_MODS;
        kbd_dev->lock_keys = 0;
        
        kbd_dev->repeat.key_new = 0;
        kbd_dev->repeat.key_repeated = 0;
        kbd_dev->repeat.delay_before = DEFAULT_DELAY_BEFORE_FIRST_REPEAT;
        kbd_dev->repeat.delay_between = DEFAULT_REPEAT_DELAY;
        
        kbd_dev->repeat_mtx = (fibril_mutex_t *)(
            malloc(sizeof(fibril_mutex_t)));
        if (kbd_dev->repeat_mtx == NULL) {
                usb_log_fatal("No memory!\n");
                free(kbd_dev->keys);
                return ENOMEM;
        }
        
        fibril_mutex_initialize(kbd_dev->repeat_mtx);
        
        /*
         * Set boot protocol.
         * Set LEDs according to initial setup.
         * Set Idle rate
         */
        assert(kbd_dev->hid_dev != NULL);
        assert(kbd_dev->hid_dev->initialized);
        usbhid_req_set_protocol(kbd_dev->hid_dev, USB_HID_PROTOCOL_BOOT);
        
        usbhid_kbd_set_led(kbd_dev);
        
        usbhid_req_set_idle(kbd_dev->hid_dev, IDLE_RATE);
        
        kbd_dev->initialized = 1;
        usb_log_info("HID/KBD device structure initialized.\n");
        
        return EOK;
}

/*----------------------------------------------------------------------------*/
/* HID/KBD polling                                                            */
/*----------------------------------------------------------------------------*/
/**
 * Main keyboard polling function.
 *
 * This function uses the Interrupt In pipe of the keyboard to poll for events.
 * The keyboard is initialized in a way that it reports only when a key is 
 * pressed or released, so there is no actual need for any sleeping between
 * polls (see usbhid_kbd_try_add_device() or usbhid_kbd_init()).
 *
 * @param kbd_dev Initialized keyboard structure representing the device to 
 *                poll.
 *
 * @sa usbhid_kbd_process_data()
 */
static void usbhid_kbd_poll(usbhid_kbd_t *kbd_dev)
{
        int rc, sess_rc;
        uint8_t buffer[BOOTP_BUFFER_SIZE];
        size_t actual_size;
        
        usb_log_info("Polling keyboard...\n");
        
        if (!kbd_dev->initialized) {
                usb_log_error("HID/KBD device not initialized!\n");
                return;
        }
        
        assert(kbd_dev->hid_dev != NULL);
        assert(kbd_dev->hid_dev->initialized);

        while (true) {
                sess_rc = usb_endpoint_pipe_start_session(
                    &kbd_dev->hid_dev->poll_pipe);
                if (sess_rc != EOK) {
                        usb_log_warning("Failed to start a session: %s.\n",
                            str_error(sess_rc));
                        continue;
                }

                rc = usb_endpoint_pipe_read(&kbd_dev->hid_dev->poll_pipe, 
                    buffer, BOOTP_BUFFER_SIZE, &actual_size);
                
                sess_rc = usb_endpoint_pipe_end_session(
                    &kbd_dev->hid_dev->poll_pipe);

                if (rc != EOK) {
                        usb_log_warning("Error polling the keyboard: %s.\n",
                            str_error(rc));
                        continue;
                }

                if (sess_rc != EOK) {
                        usb_log_warning("Error closing session: %s.\n",
                            str_error(sess_rc));
                        continue;
                }

                /*
                 * If the keyboard answered with NAK, it returned no data.
                 * This implies that no change happened since last query.
                 */
                if (actual_size == 0) {
                        usb_log_debug("Keyboard returned NAK\n");
                        continue;
                }

                /*
                 * TODO: Process pressed keys.
                 */
                usb_log_debug("Calling usbhid_kbd_process_data()\n");
                usbhid_kbd_process_data(kbd_dev, buffer, actual_size);
                
                // disabled for now, no reason to sleep
                //async_usleep(kbd_dev->hid_dev->poll_interval);
        }

        // not reached
        assert(0);
}

/*----------------------------------------------------------------------------*/
/**
 * Function executed by the main driver fibril.
 *
 * Just starts polling the keyboard for events.
 * 
 * @param arg Initialized keyboard device structure (of type usbhid_kbd_t) 
 *            representing the device.
 *
 * @retval EOK if the fibril finished polling the device.
 * @retval EINVAL if no device was given in the argument.
 *
 * @sa usbhid_kbd_poll()
 *
 * @todo Change return value - only case when the fibril finishes is in case
 *       of some error, so the error should probably be propagated from function
 *       usbhid_kbd_poll() to here and up.
 */
static int usbhid_kbd_fibril(void *arg)
{
        if (arg == NULL) {
                usb_log_error("No device!\n");
                return EINVAL;
        }
        
        usbhid_kbd_t *kbd_dev = (usbhid_kbd_t *)arg;

        usbhid_kbd_poll(kbd_dev);
        
        // at the end, properly destroy the KBD structure
        usbhid_kbd_free(&kbd_dev);
        assert(kbd_dev == NULL);

        return EOK;
}

/*----------------------------------------------------------------------------*/
/* API functions                                                              */
/*----------------------------------------------------------------------------*/
/**
 * Function for adding a new device of type USB/HID/keyboard.
 *
 * This functions initializes required structures from the device's descriptors
 * and starts a new fibril for polling the keyboard for events.
 *
 * During initialization, the keyboard is switched into boot protocol, the idle
 * rate is set to 0 (infinity), resulting in the keyboard only reporting event
 * when a key is pressed or released. Finally, the LED lights are turned on 
 * according to the default setup of lock keys.
 *
 * @note By default, the keyboards is initialized with Num Lock turned on and 
 *       other locks turned off.
 * @note Currently supports only boot-protocol keyboards.
 *
 * @param dev Device to add.
 *
 * @retval EOK if successful.
 * @retval ENOMEM if there
 * @return Other error code inherited from one of functions usbhid_kbd_init(),
 *         ddf_fun_bind() and ddf_fun_add_to_class().
 *
 * @sa usbhid_kbd_fibril()
 */
int usbhid_kbd_try_add_device(ddf_dev_t *dev)
{
        /*
         * Create default function.
         */
        ddf_fun_t *kbd_fun = ddf_fun_create(dev, fun_exposed, "keyboard");
        if (kbd_fun == NULL) {
                usb_log_error("Could not create DDF function node.\n");
                return ENOMEM;
        }
        
        /* 
         * Initialize device (get and process descriptors, get address, etc.)
         */
        usb_log_info("Initializing USB/HID KBD device...\n");
        
        usbhid_kbd_t *kbd_dev = usbhid_kbd_new();
        if (kbd_dev == NULL) {
                usb_log_error("Error while creating USB/HID KBD device "
                    "structure.\n");
                ddf_fun_destroy(kbd_fun);
                return ENOMEM;  // TODO: some other code??
        }
        
        int rc = usbhid_kbd_init(kbd_dev, dev);
        
        if (rc != EOK) {
                usb_log_error("Failed to initialize USB/HID KBD device.\n");
                ddf_fun_destroy(kbd_fun);
                usbhid_kbd_free(&kbd_dev);
                return rc;
        }       
        
        usb_log_info("USB/HID KBD device structure initialized.\n");
        
        /*
         * Store the initialized keyboard device and keyboard ops
         * to the DDF function.
         */
        kbd_fun->driver_data = kbd_dev;
        kbd_fun->ops = &keyboard_ops;

        rc = ddf_fun_bind(kbd_fun);
        if (rc != EOK) {
                usb_log_error("Could not bind DDF function.\n");
                // TODO: Can / should I destroy the DDF function?
                ddf_fun_destroy(kbd_fun);
                usbhid_kbd_free(&kbd_dev);
                return rc;
        }
        
        rc = ddf_fun_add_to_class(kbd_fun, "keyboard");
        if (rc != EOK) {
                usb_log_error("Could not add DDF function to class 'keyboard'"
                    "\n");
                // TODO: Can / should I destroy the DDF function?
                ddf_fun_destroy(kbd_fun);
                usbhid_kbd_free(&kbd_dev);
                return rc;
        }
        
        /*
         * Create new fibril for handling this keyboard
         */
        fid_t fid = fibril_create(usbhid_kbd_fibril, kbd_dev);
        if (fid == 0) {
                usb_log_error("Failed to start fibril for KBD device\n");
                return ENOMEM;
        }
        fibril_add_ready(fid);
        
        /*
         * Create new fibril for auto-repeat
         */
        fid = fibril_create(usbhid_kbd_repeat_fibril, kbd_dev);
        if (fid == 0) {
                usb_log_error("Failed to start fibril for KBD auto-repeat");
                return ENOMEM;
        }
        fibril_add_ready(fid);

        (void)keyboard_ops;

        /*
         * Hurrah, device is initialized.
         */
        return EOK;
}

/**
 * @}
 */