kgdboc,keyboard: Keyboard driver for kdb with kgdb

This patch adds in the kdb PS/2 keyboard driver.  This was mostly a
direct port from the original kdb where I cleaned up the code against
checkpatch.pl and added the glue to stitch it into kgdb.

This patch also enables early kdb debug via kgdbwait and the keyboard.

All the access to configure kdb using either a serial console or the
keyboard is done via kgdboc.

If you want to use only the keyboard and want to break in early you
would add to your kernel command arguments:

    kgdboc=kbd kgdbwait

If you wanted serial and or the keyboard access you could use:

    kgdboc=kbd,ttyS0

You can also configure kgdboc as a kernel module or at run time with
the sysfs where you can activate and deactivate kgdb.

Turn it on:
    echo kbd,ttyS0 > /sys/module/kgdboc/parameters/kgdboc

Turn it off:
    echo "" > /sys/module/kgdboc/parameters/kgdboc

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 212 insertions, 0 deletions

diff --git a/kernel/debug/kdb/kdb_keyboard.c b/kernel/debug/kdb/kdb_keyboard.c
new file mode 100644
index 000000000000..4bca634975c0
--- /dev/null
+++ b/kernel/debug/kdb/kdb_keyboard.c
@@ -0,0 +1,212 @@
+/*
+ * 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;
+
+/*
+ * 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)
+                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 & 0x7f) == 0x1c) {
+                /*
+                 * enter key.  All done.  Absorb the release scancode.
+                 */
+                while ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
+                        ;
+
+                /*
+                 * Fetch the scancode
+                 */
+                scancode = inb(KBD_DATA_REG);
+                scanstatus = inb(KBD_STATUS_REG);
+
+                while (scanstatus & KBD_STAT_MOUSE_OBF) {
+                        scancode = inb(KBD_DATA_REG);
+                        scanstatus = inb(KBD_STATUS_REG);
+                }
+
+                if (scancode != 0x9c) {
+                        /*
+                         * Wasn't an enter-release,  why not?
+                         */
+                        kdb_printf("kdb: expected enter got 0x%x status 0x%x\n",
+                               scancode, scanstatus);
+                }
+
+                return 13;
+        }
+
+        return keychar & 0xff;
+}
+EXPORT_SYMBOL_GPL(kdb_get_kbd_char);