kdb_keyboard.c

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/*
 * Kernel Debugger Architecture Dependent Console I/O handler
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.
 *
 * Copyright (c) 1999-2006 Silicon Graphics, Inc.  All Rights Reserved.
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 */

#include <linux/kdb.h>
#include <linux/keyboard.h>
#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/io.h>

/* Keyboard Controller Registers on normal PCs. */

#define KBD_STATUS_REG      0x64    /* Status register (R) */
#define KBD_DATA_REG        0x60    /* Keyboard data register (R/W) */

/* Status Register Bits */

#define KBD_STAT_OBF        0x01    /* Keyboard output buffer full */
#define KBD_STAT_MOUSE_OBF  0x20    /* Mouse output buffer full */

static int kbd_exists;
static int kbd_last_ret;

/*
 * Check if the keyboard controller has a keypress for us.
 * Some parts (Enter Release, LED change) are still blocking polled here,
 * but hopefully they are all short.
 */
int kdb_get_kbd_char(void)
{
    int scancode, scanstatus;
    static int shift_lock;  /* CAPS LOCK state (0-off, 1-on) */
    static int shift_key;   /* Shift next keypress */
    static int ctrl_key;
    u_short keychar;

    if (KDB_FLAG(NO_I8042) || KDB_FLAG(NO_VT_CONSOLE) ||
        (inb(KBD_STATUS_REG) == 0xff && inb(KBD_DATA_REG) == 0xff)) {
        kbd_exists = 0;
        return -1;
    }
    kbd_exists = 1;

    if ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
        return -1;

    /*
     * Fetch the scancode
     */
    scancode = inb(KBD_DATA_REG);
    scanstatus = inb(KBD_STATUS_REG);

    /*
     * Ignore mouse events.
     */
    if (scanstatus & KBD_STAT_MOUSE_OBF)
        return -1;

    /*
     * Ignore release, trigger on make
     * (except for shift keys, where we want to
     *  keep the shift state so long as the key is
     *  held down).
     */

    if (((scancode&0x7f) == 0x2a) || ((scancode&0x7f) == 0x36)) {
        /*
         * Next key may use shift table
         */
        if ((scancode & 0x80) == 0)
            shift_key = 1;
        else
            shift_key = 0;
        return -1;
    }

    if ((scancode&0x7f) == 0x1d) {
        /*
         * Left ctrl key
         */
        if ((scancode & 0x80) == 0)
            ctrl_key = 1;
        else
            ctrl_key = 0;
        return -1;
    }

    if ((scancode & 0x80) != 0) {
        if (scancode == 0x9c)
            kbd_last_ret = 0;
        return -1;
    }

    scancode &= 0x7f;

    /*
     * Translate scancode
     */

    if (scancode == 0x3a) {
        /*
         * Toggle caps lock
         */
        shift_lock ^= 1;

#ifdef  KDB_BLINK_LED
        kdb_toggleled(0x4);
#endif
        return -1;
    }

    if (scancode == 0x0e) {
        /*
         * Backspace
         */
        return 8;
    }

    /* Special Key */
    switch (scancode) {
    case 0xF: /* Tab */
        return 9;
    case 0x53: /* Del */
        return 4;
    case 0x47: /* Home */
        return 1;
    case 0x4F: /* End */
        return 5;
    case 0x4B: /* Left */
        return 2;
    case 0x48: /* Up */
        return 16;
    case 0x50: /* Down */
        return 14;
    case 0x4D: /* Right */
        return 6;
    }

    if (scancode == 0xe0)
        return -1;

    /*
     * For Japanese 86/106 keyboards
     *  See comment in drivers/char/pc_keyb.c.
     *  - Masahiro Adegawa
     */
    if (scancode == 0x73)
        scancode = 0x59;
    else if (scancode == 0x7d)
        scancode = 0x7c;

    if (!shift_lock && !shift_key && !ctrl_key) {
        keychar = plain_map[scancode];
    } else if ((shift_lock || shift_key) && key_maps[1]) {
        keychar = key_maps[1][scancode];
    } else if (ctrl_key && key_maps[4]) {
        keychar = key_maps[4][scancode];
    } else {
        keychar = 0x0020;
        kdb_printf("Unknown state/scancode (%d)\n", scancode);
    }
    keychar &= 0x0fff;
    if (keychar == '\t')
        keychar = ' ';
    switch (KTYP(keychar)) {
    case KT_LETTER:
    case KT_LATIN:
        if (isprint(keychar))
            break;      /* printable characters */
        /* drop through */
    case KT_SPEC:
        if (keychar == K_ENTER)
            break;
        /* drop through */
    default:
        return -1;  /* ignore unprintables */
    }

    if (scancode == 0x1c) {
        kbd_last_ret = 1;
        return 13;
    }

    return keychar & 0xff;
}
EXPORT_SYMBOL_GPL(kdb_get_kbd_char);

/*
 * Best effort cleanup of ENTER break codes on leaving KDB. Called on
 * exiting KDB, when we know we processed an ENTER or KP ENTER scan
 * code.
 */
void kdb_kbd_cleanup_state(void)
{
    int scancode, scanstatus;

    /*
     * Nothing to clean up, since either
     * ENTER was never pressed, or has already
     * gotten cleaned up.
     */
    if (!kbd_last_ret)
        return;

    kbd_last_ret = 0;
    /*
     * Enter key. Need to absorb the break code here, lest it gets
     * leaked out if we exit KDB as the result of processing 'g'.
     *
     * This has several interesting implications:
     * + Need to handle KP ENTER, which has break code 0xe0 0x9c.
     * + Need to handle repeat ENTER and repeat KP ENTER. Repeats
     *   only get a break code at the end of the repeated
     *   sequence. This means we can't propagate the repeated key
     *   press, and must swallow it away.
     * + Need to handle possible PS/2 mouse input.
     * + Need to handle mashed keys.
     */

    while (1) {
        while ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
            cpu_relax();

        /*
         * Fetch the scancode.
         */
        scancode = inb(KBD_DATA_REG);
        scanstatus = inb(KBD_STATUS_REG);

        /*
         * Skip mouse input.
         */
        if (scanstatus & KBD_STAT_MOUSE_OBF)
            continue;

        /*
         * If we see 0xe0, this is either a break code for KP
         * ENTER, or a repeat make for KP ENTER. Either way,
         * since the second byte is equivalent to an ENTER,
         * skip the 0xe0 and try again.
         *
         * If we see 0x1c, this must be a repeat ENTER or KP
         * ENTER (and we swallowed 0xe0 before). Try again.
         *
         * We can also see make and break codes for other keys
         * mashed before or after pressing ENTER. Thus, if we
         * see anything other than 0x9c, we have to try again.
         *
         * Note, if you held some key as ENTER was depressed,
         * that break code would get leaked out.
         */
        if (scancode != 0x9c)
            continue;

        return;
    }
}