/*
 * Atari Keyboard driver for 680x0 Linux
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

/*
 * Atari support by Robert de Vries
 * enhanced by Bjoern Brauel and Roman Hodek
 *
 * 2.6 and input cleanup (removed autorepeat stuff) for 2.6.21
 * 06/07 Michael Schmitz
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/keyboard.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/kd.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/kbd_kern.h>

#include <asm/atariints.h>
#include <asm/atarihw.h>
#include <asm/atarikb.h>
#include <asm/atari_joystick.h>
#include <asm/irq.h>


/* Hook for MIDI serial driver */
void (*atari_MIDI_interrupt_hook) (void);
/* Hook for keyboard inputdev  driver */
void (*atari_input_keyboard_interrupt_hook) (unsigned char, char);
/* Hook for mouse inputdev  driver */
void (*atari_input_mouse_interrupt_hook) (char *);
EXPORT_SYMBOL(atari_input_keyboard_interrupt_hook);
EXPORT_SYMBOL(atari_input_mouse_interrupt_hook);

/* variables for IKBD self test: */

/* state: 0: off; >0: in progress; >1: 0xf1 received */
static volatile int ikbd_self_test;
/* timestamp when last received a char */
static volatile unsigned long self_test_last_rcv;
/* bitmap of keys reported as broken */
static unsigned long broken_keys[128/(sizeof(unsigned long)*8)] = { 0, };

#define BREAK_MASK      (0x80)

/*
 * ++roman: The following changes were applied manually:
 *
 *  - The Alt (= Meta) key works in combination with Shift and
 *    Control, e.g. Alt+Shift+a sends Meta-A (0xc1), Alt+Control+A sends
 *    Meta-Ctrl-A (0x81) ...
 *
 *  - The parentheses on the keypad send '(' and ')' with all
 *    modifiers (as would do e.g. keypad '+'), but they cannot be used as
 *    application keys (i.e. sending Esc O c).
 *
 *  - HELP and UNDO are mapped to be F21 and F24, resp, that send the
 *    codes "\E[M" and "\E[P". (This is better than the old mapping to
 *    F11 and F12, because these codes are on Shift+F1/2 anyway.) This
 *    way, applications that allow their own keyboard mappings
 *    (e.g. tcsh, X Windows) can be configured to use them in the way
 *    the label suggests (providing help or undoing).
 *
 *  - Console switching is done with Alt+Fx (consoles 1..10) and
 *    Shift+Alt+Fx (consoles 11..20).
 *
 *  - The misc. special function implemented in the kernel are mapped
 *    to the following key combinations:
 *
 *      ClrHome          -> Home/Find
 *      Shift + ClrHome  -> End/Select
 *      Shift + Up       -> Page Up
 *      Shift + Down     -> Page Down
 *      Alt + Help       -> show system status
 *      Shift + Help     -> show memory info
 *      Ctrl + Help      -> show registers
 *      Ctrl + Alt + Del -> Reboot
 *      Alt + Undo       -> switch to last console
 *      Shift + Undo     -> send interrupt
 *      Alt + Insert     -> stop/start output (same as ^S/^Q)
 *      Alt + Up         -> Scroll back console (if implemented)
 *      Alt + Down       -> Scroll forward console (if implemented)
 *      Alt + CapsLock   -> NumLock
 *
 * ++Andreas:
 *
 *  - Help mapped to K_HELP
 *  - Undo mapped to K_UNDO (= K_F246)
 *  - Keypad Left/Right Parenthesis mapped to new K_PPAREN[LR]
 */

typedef enum kb_state_t {
        KEYBOARD, AMOUSE, RMOUSE, JOYSTICK, CLOCK, RESYNC
} KB_STATE_T;

#define IS_SYNC_CODE(sc)        ((sc) >= 0x04 && (sc) <= 0xfb)

typedef struct keyboard_state {
        unsigned char buf[6];
        int len;
        KB_STATE_T state;
} KEYBOARD_STATE;

KEYBOARD_STATE kb_state;

/* ++roman: If a keyboard overrun happened, we can't tell in general how much
 * bytes have been lost and in which state of the packet structure we are now.
 * This usually causes keyboards bytes to be interpreted as mouse movements
 * and vice versa, which is very annoying. It seems better to throw away some
 * bytes (that are usually mouse bytes) than to misinterpret them. Therefore I
 * introduced the RESYNC state for IKBD data. In this state, the bytes up to
 * one that really looks like a key event (0x04..0xf2) or the start of a mouse
 * packet (0xf8..0xfb) are thrown away, but at most 2 bytes. This at least
 * speeds up the resynchronization of the event structure, even if maybe a
 * mouse movement is lost. However, nothing is perfect. For bytes 0x01..0x03,
 * it's really hard to decide whether they're mouse or keyboard bytes. Since
 * overruns usually occur when moving the Atari mouse rapidly, they're seen as
 * mouse bytes here. If this is wrong, only a make code of the keyboard gets
 * lost, which isn't too bad. Losing a break code would be disastrous,
 * because then the keyboard repeat strikes...
 */

static irqreturn_t atari_keyboard_interrupt(int irq, void *dummy)
{
        u_char acia_stat;
        int scancode;
        int break_flag;

repeat:
        if (acia.mid_ctrl & ACIA_IRQ)
                if (atari_MIDI_interrupt_hook)
                        atari_MIDI_interrupt_hook();
        acia_stat = acia.key_ctrl;
        /* check out if the interrupt came from this ACIA */
        if (!((acia_stat | acia.mid_ctrl) & ACIA_IRQ))
                return IRQ_HANDLED;

        if (acia_stat & ACIA_OVRN) {
                /* a very fast typist or a slow system, give a warning */
                /* ...happens often if interrupts were disabled for too long */
                pr_debug("Keyboard overrun\n");
                scancode = acia.key_data;
                if (ikbd_self_test)
                        /* During self test, don't do resyncing, just process the code */
                        goto interpret_scancode;
                else if (IS_SYNC_CODE(scancode)) {
                        /* This code seem already to be the start of a new packet or a
                         * single scancode */
                        kb_state.state = KEYBOARD;
                        goto interpret_scancode;
                } else {
                        /* Go to RESYNC state and skip this byte */
                        kb_state.state = RESYNC;
                        kb_state.len = 1;       /* skip max. 1 another byte */
                        goto repeat;
                }
        }

        if (acia_stat & ACIA_RDRF) {
                /* received a character */
                scancode = acia.key_data;       /* get it or reset the ACIA, I'll get it! */
        interpret_scancode:
                switch (kb_state.state) {
                case KEYBOARD:
                        switch (scancode) {
                        case 0xF7:
                                kb_state.state = AMOUSE;
                                kb_state.len = 0;
                                break;

                        case 0xF8:
                        case 0xF9:
                        case 0xFA:
                        case 0xFB:
                                kb_state.state = RMOUSE;
                                kb_state.len = 1;
                                kb_state.buf[0] = scancode;
                                break;

                        case 0xFC:
                                kb_state.state = CLOCK;
                                kb_state.len = 0;
                                break;

                        case 0xFE:
                        case 0xFF:
                                kb_state.state = JOYSTICK;
                                kb_state.len = 1;
                                kb_state.buf[0] = scancode;
                                break;

                        case 0xF1:
                                /* during self-test, note that 0xf1 received */
                                if (ikbd_self_test) {
                                        ++ikbd_self_test;
                                        self_test_last_rcv = jiffies;
                                        break;
                                }
                                fallthrough;

                        default:
                                break_flag = scancode & BREAK_MASK;
                                scancode &= ~BREAK_MASK;
                                if (ikbd_self_test) {
                                        /* Scancodes sent during the self-test stand for broken
                                         * keys (keys being down). The code *should* be a break
                                         * code, but nevertheless some AT keyboard interfaces send
                                         * make codes instead. Therefore, simply ignore
                                         * break_flag...
                                         */
                                        int keyval, keytyp;

                                        set_bit(scancode, broken_keys);
                                        self_test_last_rcv = jiffies;
                                        /* new Linux scancodes; approx. */
                                        keyval = scancode;
                                        keytyp = KTYP(keyval) - 0xf0;
                                        keyval = KVAL(keyval);

                                        pr_warn("Key with scancode %d ", scancode);
                                        if (keytyp == KT_LATIN || keytyp == KT_LETTER) {
                                                if (keyval < ' ')
                                                        pr_cont("('^%c') ", keyval + '@');
                                                else
                                                        pr_cont("('%c') ", keyval);
                                        }
                                        pr_cont("is broken -- will be ignored.\n");
                                        break;
                                } else if (test_bit(scancode, broken_keys))
                                        break;

                                if (atari_input_keyboard_interrupt_hook)
                                        atari_input_keyboard_interrupt_hook((unsigned char)scancode, !break_flag);
                                break;
                        }
                        break;

                case AMOUSE:
                        kb_state.buf[kb_state.len++] = scancode;
                        if (kb_state.len == 5) {
                                kb_state.state = KEYBOARD;
                                /* not yet used */
                                /* wake up someone waiting for this */
                        }
                        break;

                case RMOUSE:
                        kb_state.buf[kb_state.len++] = scancode;
                        if (kb_state.len == 3) {
                                kb_state.state = KEYBOARD;
                                if (atari_input_mouse_interrupt_hook)
                                        atari_input_mouse_interrupt_hook(kb_state.buf);
                        }
                        break;

                case JOYSTICK:
                        kb_state.buf[1] = scancode;
                        kb_state.state = KEYBOARD;
#ifdef FIXED_ATARI_JOYSTICK
                        atari_joystick_interrupt(kb_state.buf);
#endif
                        break;

                case CLOCK:
                        kb_state.buf[kb_state.len++] = scancode;
                        if (kb_state.len == 6) {
                                kb_state.state = KEYBOARD;
                                /* wake up someone waiting for this.
                                   But will this ever be used, as Linux keeps its own time.
                                   Perhaps for synchronization purposes? */
                                /* wake_up_interruptible(&clock_wait); */
                        }
                        break;

                case RESYNC:
                        if (kb_state.len <= 0 || IS_SYNC_CODE(scancode)) {
                                kb_state.state = KEYBOARD;
                                goto interpret_scancode;
                        }
                        kb_state.len--;
                        break;
                }
        }

#if 0
        if (acia_stat & ACIA_CTS)
                /* cannot happen */;
#endif

        if (acia_stat & (ACIA_FE | ACIA_PE)) {
                pr_err("Error in keyboard communication\n");
        }

        /* handle_scancode() can take a lot of time, so check again if
         * some character arrived
         */
        goto repeat;
}

/*
 * I write to the keyboard without using interrupts, I poll instead.
 * This takes for the maximum length string allowed (7) at 7812.5 baud
 * 8 data 1 start 1 stop bit: 9.0 ms
 * If this takes too long for normal operation, interrupt driven writing
 * is the solution. (I made a feeble attempt in that direction but I
 * kept it simple for now.)
 */
void ikbd_write(const char *str, int len)
{
        u_char acia_stat;

        if ((len < 1) || (len > 7))
                panic("ikbd: maximum string length exceeded");
        while (len) {
                acia_stat = acia.key_ctrl;
                if (acia_stat & ACIA_TDRE) {
                        acia.key_data = *str++;
                        len--;
                }
        }
}

/* Reset (without touching the clock) */
static void ikbd_reset(void)
{
        static const char cmd[2] = { 0x80, 0x01 };

        ikbd_write(cmd, 2);

        /*
         * if all's well code 0xF1 is returned, else the break codes of
         * all keys making contact
         */
}

/* Set mouse button action */
void ikbd_mouse_button_action(int mode)
{
        char cmd[2] = { 0x07, mode };

        ikbd_write(cmd, 2);
}

/* Set relative mouse position reporting */
void ikbd_mouse_rel_pos(void)
{
        static const char cmd[1] = { 0x08 };

        ikbd_write(cmd, 1);
}
EXPORT_SYMBOL(ikbd_mouse_rel_pos);

/* Set absolute mouse position reporting */
void ikbd_mouse_abs_pos(int xmax, int ymax)
{
        char cmd[5] = { 0x09, xmax>>8, xmax&0xFF, ymax>>8, ymax&0xFF };

        ikbd_write(cmd, 5);
}

/* Set mouse keycode mode */
void ikbd_mouse_kbd_mode(int dx, int dy)
{
        char cmd[3] = { 0x0A, dx, dy };

        ikbd_write(cmd, 3);
}

/* Set mouse threshold */
void ikbd_mouse_thresh(int x, int y)
{
        char cmd[3] = { 0x0B, x, y };

        ikbd_write(cmd, 3);
}
EXPORT_SYMBOL(ikbd_mouse_thresh);

/* Set mouse scale */
void ikbd_mouse_scale(int x, int y)
{
        char cmd[3] = { 0x0C, x, y };

        ikbd_write(cmd, 3);
}

/* Interrogate mouse position */
void ikbd_mouse_pos_get(int *x, int *y)
{
        static const char cmd[1] = { 0x0D };

        ikbd_write(cmd, 1);

        /* wait for returning bytes */
}

/* Load mouse position */
void ikbd_mouse_pos_set(int x, int y)
{
        char cmd[6] = { 0x0E, 0x00, x>>8, x&0xFF, y>>8, y&0xFF };

        ikbd_write(cmd, 6);
}

/* Set Y=0 at bottom */
void ikbd_mouse_y0_bot(void)
{
        static const char cmd[1] = { 0x0F };

        ikbd_write(cmd, 1);
}

/* Set Y=0 at top */
void ikbd_mouse_y0_top(void)
{
        static const char cmd[1] = { 0x10 };

        ikbd_write(cmd, 1);
}
EXPORT_SYMBOL(ikbd_mouse_y0_top);

/* Disable mouse */
void ikbd_mouse_disable(void)
{
        static const char cmd[1] = { 0x12 };

        ikbd_write(cmd, 1);
}
EXPORT_SYMBOL(ikbd_mouse_disable);

/* Set joystick event reporting */
void ikbd_joystick_event_on(void)
{
        static const char cmd[1] = { 0x14 };

        ikbd_write(cmd, 1);
}

/* Set joystick interrogation mode */
void ikbd_joystick_event_off(void)
{
        static const char cmd[1] = { 0x15 };

        ikbd_write(cmd, 1);
}

/* Joystick interrogation */
void ikbd_joystick_get_state(void)
{
        static const char cmd[1] = { 0x16 };

        ikbd_write(cmd, 1);
}

#if 0
/* This disables all other ikbd activities !!!! */
/* Set joystick monitoring */
void ikbd_joystick_monitor(int rate)
{
        static const char cmd[2] = { 0x17, rate };

        ikbd_write(cmd, 2);

        kb_state.state = JOYSTICK_MONITOR;
}
#endif

/* some joystick routines not in yet (0x18-0x19) */

/* Disable joysticks */
void ikbd_joystick_disable(void)
{
        static const char cmd[1] = { 0x1A };

        ikbd_write(cmd, 1);
}

/*
 * The original code sometimes left the interrupt line of
 * the ACIAs low forever. I hope, it is fixed now.
 *
 * Martin Rogge, 20 Aug 1995
 */

static int atari_keyb_done = 0;

int atari_keyb_init(void)
{
        int error;

        if (atari_keyb_done)
                return 0;

        kb_state.state = KEYBOARD;
        kb_state.len = 0;

        error = request_irq(IRQ_MFP_ACIA, atari_keyboard_interrupt, 0,
                            "keyboard,mouse,MIDI", atari_keyboard_interrupt);
        if (error)
                return error;

        atari_turnoff_irq(IRQ_MFP_ACIA);
        do {
                /* reset IKBD ACIA */
                acia.key_ctrl = ACIA_RESET |
                                ((atari_switches & ATARI_SWITCH_IKBD) ?
                                 ACIA_RHTID : 0);
                (void)acia.key_ctrl;
                (void)acia.key_data;

                /* reset MIDI ACIA */
                acia.mid_ctrl = ACIA_RESET |
                                ((atari_switches & ATARI_SWITCH_MIDI) ?
                                 ACIA_RHTID : 0);
                (void)acia.mid_ctrl;
                (void)acia.mid_data;

                /* divide 500kHz by 64 gives 7812.5 baud */
                /* 8 data no parity 1 start 1 stop bit */
                /* receive interrupt enabled */
                /* RTS low (except if switch selected), transmit interrupt disabled */
                acia.key_ctrl = (ACIA_DIV64|ACIA_D8N1S|ACIA_RIE) |
                                ((atari_switches & ATARI_SWITCH_IKBD) ?
                                 ACIA_RHTID : ACIA_RLTID);

                acia.mid_ctrl = ACIA_DIV16 | ACIA_D8N1S |
                                ((atari_switches & ATARI_SWITCH_MIDI) ?
                                 ACIA_RHTID : 0);

        /* make sure the interrupt line is up */
        } while ((st_mfp.par_dt_reg & 0x10) == 0);

        /* enable ACIA Interrupts */
        st_mfp.active_edge &= ~0x10;
        atari_turnon_irq(IRQ_MFP_ACIA);

        ikbd_self_test = 1;
        ikbd_reset();
        /* wait for a period of inactivity (here: 0.25s), then assume the IKBD's
         * self-test is finished */
        self_test_last_rcv = jiffies;
        while (time_before(jiffies, self_test_last_rcv + HZ/4))
                barrier();
        /* if not incremented: no 0xf1 received */
        if (ikbd_self_test == 1)
                pr_err("Keyboard self test failed!\n");
        ikbd_self_test = 0;

        ikbd_mouse_disable();
        ikbd_joystick_disable();

#ifdef FIXED_ATARI_JOYSTICK
        atari_joystick_init();
#endif

        // flag init done
        atari_keyb_done = 1;
        return 0;
}
EXPORT_SYMBOL_GPL(atari_keyb_init);