// SPDX-License-Identifier: GPL-2.0
/*
 *    IBM/3270 Driver - tty functions.
 *
 *  Author(s):
 *    Original 3270 Code for 2.4 written by Richard Hitt (UTS Global)
 *    Rewritten for 2.5 by Martin Schwidefsky <schwidefsky@de.ibm.com>
 *      -- Copyright IBM Corp. 2003
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/tty.h>
#include <linux/vt_kern.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/panic_notifier.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/memblock.h>

#include <asm/machine.h>
#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/ebcdic.h>
#include <asm/cpcmd.h>
#include <linux/uaccess.h>

#include "raw3270.h"
#include "keyboard.h"

#define TTY3270_CHAR_BUF_SIZE 256
#define TTY3270_OUTPUT_BUFFER_SIZE 4096
#define TTY3270_SCREEN_PAGES 8 /* has to be power-of-two */
#define TTY3270_RECALL_SIZE 16 /* has to be power-of-two */
#define TTY3270_STATUS_AREA_SIZE 40

static struct tty_driver *tty3270_driver;
static int tty3270_max_index;
static struct raw3270_fn tty3270_fn;

#define TTY3270_HIGHLIGHT_BLINK         1
#define TTY3270_HIGHLIGHT_REVERSE       2
#define TTY3270_HIGHLIGHT_UNDERSCORE    4

struct tty3270_attribute {
        unsigned char alternate_charset:1;      /* Graphics charset */
        unsigned char highlight:3;              /* Blink/reverse/underscore */
        unsigned char f_color:4;                /* Foreground color */
        unsigned char b_color:4;                /* Background color */
};

struct tty3270_cell {
        u8 character;
        struct tty3270_attribute attributes;
};

struct tty3270_line {
        struct tty3270_cell *cells;
        int len;
        int dirty;
};

static const unsigned char sfq_read_partition[] = {
        0x00, 0x07, 0x01, 0xff, 0x03, 0x00, 0x81
};

#define ESCAPE_NPAR 8

/*
 * The main tty view data structure.
 * FIXME:
 * 1) describe line orientation & lines list concept against screen
 * 2) describe conversion of screen to lines
 * 3) describe line format.
 */
struct tty3270 {
        struct raw3270_view view;
        struct tty_port port;

        /* Output stuff. */
        unsigned char wcc;              /* Write control character. */
        int nr_up;                      /* # lines up in history. */
        unsigned long update_flags;     /* Update indication bits. */
        struct raw3270_request *write;  /* Single write request. */
        struct timer_list timer;        /* Output delay timer. */
        char *converted_line;           /* RAW 3270 data stream */
        unsigned int line_view_start;   /* Start of visible area */
        unsigned int line_write_start;  /* current write position */
        unsigned int oops_line;         /* line counter used when print oops */

        /* Current tty screen. */
        unsigned int cx, cy;            /* Current output position. */
        struct tty3270_attribute attributes;
        struct tty3270_attribute saved_attributes;
        int allocated_lines;
        struct tty3270_line *screen;

        /* Input stuff. */
        char *prompt;                   /* Output string for input area. */
        size_t prompt_sz;               /* Size of output string. */
        char *input;                    /* Input string for read request. */
        struct raw3270_request *read;   /* Single read request. */
        struct raw3270_request *kreset; /* Single keyboard reset request. */
        struct raw3270_request *readpartreq;
        unsigned char inattr;           /* Visible/invisible input. */
        int throttle, attn;             /* tty throttle/unthrottle. */
        struct tasklet_struct readlet;  /* Tasklet to issue read request. */
        struct tasklet_struct hanglet;  /* Tasklet to hang up the tty. */
        struct kbd_data *kbd;           /* key_maps stuff. */

        /* Escape sequence parsing. */
        int esc_state, esc_ques, esc_npar;
        int esc_par[ESCAPE_NPAR];
        unsigned int saved_cx, saved_cy;

        /* Command recalling. */
        char **rcl_lines;               /* Array of recallable lines */
        int rcl_write_index;            /* Write index of recallable items */
        int rcl_read_index;             /* Read index of recallable items */

        /* Character array for put_char/flush_chars. */
        unsigned int char_count;
        u8 char_buf[TTY3270_CHAR_BUF_SIZE];
};

/* tty3270->update_flags. See tty3270_update for details. */
#define TTY_UPDATE_INPUT        0x1     /* Update input line. */
#define TTY_UPDATE_STATUS       0x2     /* Update status line. */
#define TTY_UPDATE_LINES        0x4     /* Update visible screen lines */
#define TTY_UPDATE_ALL          0x7     /* Recreate screen. */

#define TTY3270_INPUT_AREA_ROWS 2

/*
 * Setup timeout for a device. On timeout trigger an update.
 */
static void tty3270_set_timer(struct tty3270 *tp, int expires)
{
        mod_timer(&tp->timer, jiffies + expires);
}

static int tty3270_tty_rows(struct tty3270 *tp)
{
        return tp->view.rows - TTY3270_INPUT_AREA_ROWS;
}

static char *tty3270_add_ba(struct tty3270 *tp, char *cp, char order, int x, int y)
{
        *cp++ = order;
        raw3270_buffer_address(tp->view.dev, cp, x, y);
        return cp + 2;
}

static char *tty3270_add_ra(struct tty3270 *tp, char *cp, int x, int y, char c)
{
        cp = tty3270_add_ba(tp, cp, TO_RA, x, y);
        *cp++ = c;
        return cp;
}

static char *tty3270_add_sa(struct tty3270 *tp, char *cp, char attr, char value)
{
        *cp++ = TO_SA;
        *cp++ = attr;
        *cp++ = value;
        return cp;
}

static char *tty3270_add_ge(struct tty3270 *tp, char *cp, char c)
{
        *cp++ = TO_GE;
        *cp++ = c;
        return cp;
}

static char *tty3270_add_sf(struct tty3270 *tp, char *cp, char type)
{
        *cp++ = TO_SF;
        *cp++ = type;
        return cp;
}

static int tty3270_line_increment(struct tty3270 *tp, unsigned int line, unsigned int incr)
{
        return (line + incr) & (tp->allocated_lines - 1);
}

static struct tty3270_line *tty3270_get_write_line(struct tty3270 *tp, unsigned int num)
{
        return tp->screen + tty3270_line_increment(tp, tp->line_write_start, num);
}

static struct tty3270_line *tty3270_get_view_line(struct tty3270 *tp, unsigned int num)
{
        return tp->screen + tty3270_line_increment(tp, tp->line_view_start, num - tp->nr_up);
}

static int tty3270_input_size(int cols)
{
        return cols * 2 - 11;
}

static void tty3270_update_prompt(struct tty3270 *tp, char *input)
{
        strscpy(tp->prompt, input, tp->prompt_sz);
        tp->update_flags |= TTY_UPDATE_INPUT;
        tty3270_set_timer(tp, 1);
}

/*
 * The input line are the two last lines of the screen.
 */
static int tty3270_add_prompt(struct tty3270 *tp)
{
        int count = 0;
        char *cp;

        cp = tp->converted_line;
        cp = tty3270_add_ba(tp, cp, TO_SBA, 0, -2);
        *cp++ = tp->view.ascebc['>'];

        if (*tp->prompt) {
                cp = tty3270_add_sf(tp, cp, TF_INMDT);
                count = min_t(int, strlen(tp->prompt),
                              tp->view.cols * 2 - TTY3270_STATUS_AREA_SIZE - 2);
                memcpy(cp, tp->prompt, count);
                cp += count;
        } else {
                cp = tty3270_add_sf(tp, cp, tp->inattr);
        }
        *cp++ = TO_IC;
        /* Clear to end of input line. */
        if (count < tp->view.cols * 2 - 11)
                cp = tty3270_add_ra(tp, cp, -TTY3270_STATUS_AREA_SIZE, -1, 0);
        return cp - tp->converted_line;
}

static char *tty3270_ebcdic_convert(struct tty3270 *tp, char *d, char *s)
{
        while (*s)
                *d++ = tp->view.ascebc[(int)*s++];
        return d;
}

/*
 * The status line is the last line of the screen. It shows the string
 * "Running"/"History X" in the lower right corner of the screen.
 */
static int tty3270_add_status(struct tty3270 *tp)
{
        char *cp = tp->converted_line;
        int len;

        cp = tty3270_add_ba(tp, cp, TO_SBA, -TTY3270_STATUS_AREA_SIZE, -1);
        cp = tty3270_add_sf(tp, cp, TF_LOG);
        cp = tty3270_add_sa(tp, cp, TAT_FGCOLOR, TAC_GREEN);
        cp = tty3270_ebcdic_convert(tp, cp, " 7");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_REVER);
        cp = tty3270_ebcdic_convert(tp, cp, "PrevPg");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_RESET);
        cp = tty3270_ebcdic_convert(tp, cp, " 8");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_REVER);
        cp = tty3270_ebcdic_convert(tp, cp, "NextPg");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_RESET);
        cp = tty3270_ebcdic_convert(tp, cp, " 12");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_REVER);
        cp = tty3270_ebcdic_convert(tp, cp, "Recall");
        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_RESET);
        cp = tty3270_ebcdic_convert(tp, cp, "  ");
        if (tp->nr_up) {
                len = sprintf(cp, "History %d", -tp->nr_up);
                codepage_convert(tp->view.ascebc, cp, len);
                cp += len;
        } else {
                cp = tty3270_ebcdic_convert(tp, cp, oops_in_progress ? "Crashed" : "Running");
        }
        cp = tty3270_add_sf(tp, cp, TF_LOG);
        cp = tty3270_add_sa(tp, cp, TAT_FGCOLOR, TAC_RESET);
        return cp - (char *)tp->converted_line;
}

static void tty3270_blank_screen(struct tty3270 *tp)
{
        struct tty3270_line *line;
        int i;

        for (i = 0; i < tty3270_tty_rows(tp); i++) {
                line = tty3270_get_write_line(tp, i);
                line->len = 0;
                line->dirty = 1;
        }
        tp->nr_up = 0;
}

/*
 * Write request completion callback.
 */
static void tty3270_write_callback(struct raw3270_request *rq, void *data)
{
        struct tty3270 *tp = container_of(rq->view, struct tty3270, view);

        if (rq->rc != 0) {
                /* Write wasn't successful. Refresh all. */
                tp->update_flags = TTY_UPDATE_ALL;
                tty3270_set_timer(tp, 1);
        }
        raw3270_request_reset(rq);
        xchg(&tp->write, rq);
}

static int tty3270_required_length(struct tty3270 *tp, struct tty3270_line *line)
{
        unsigned char f_color, b_color, highlight;
        struct tty3270_cell *cell;
        int i, flen = 3;                /* Prefix (TO_SBA). */

        flen += line->len;
        highlight = 0;
        f_color = TAC_RESET;
        b_color = TAC_RESET;

        for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
                if (cell->attributes.highlight != highlight) {
                        flen += 3;      /* TO_SA to switch highlight. */
                        highlight = cell->attributes.highlight;
                }
                if (cell->attributes.f_color != f_color) {
                        flen += 3;      /* TO_SA to switch color. */
                        f_color = cell->attributes.f_color;
                }
                if (cell->attributes.b_color != b_color) {
                        flen += 3;      /* TO_SA to switch color. */
                        b_color = cell->attributes.b_color;
                }
                if (cell->attributes.alternate_charset)
                        flen += 1;      /* TO_GE to switch to graphics extensions */
        }
        if (highlight)
                flen += 3;      /* TO_SA to reset hightlight. */
        if (f_color != TAC_RESET)
                flen += 3;      /* TO_SA to reset color. */
        if (b_color != TAC_RESET)
                flen += 3;      /* TO_SA to reset color. */
        if (line->len < tp->view.cols)
                flen += 4;      /* Postfix (TO_RA). */

        return flen;
}

static char *tty3270_add_reset_attributes(struct tty3270 *tp, struct tty3270_line *line,
                                          char *cp, struct tty3270_attribute *attr, int lineno)
{
        if (attr->highlight)
                cp = tty3270_add_sa(tp, cp, TAT_EXTHI, TAX_RESET);
        if (attr->f_color != TAC_RESET)
                cp = tty3270_add_sa(tp, cp, TAT_FGCOLOR, TAX_RESET);
        if (attr->b_color != TAC_RESET)
                cp = tty3270_add_sa(tp, cp, TAT_BGCOLOR, TAX_RESET);
        if (line->len < tp->view.cols)
                cp = tty3270_add_ra(tp, cp, 0, lineno + 1, 0);
        return cp;
}

static char tty3270_graphics_translate(struct tty3270 *tp, char ch)
{
        switch (ch) {
        case 'q': /* - */
                return 0xa2;
        case 'x': /* '|' */
                return 0x85;
        case 'l': /* |- */
                return 0xc5;
        case 't': /* |_ */
                return 0xc6;
        case 'u': /* _| */
                return 0xd6;
        case 'k': /* -| */
                return 0xd5;
        case 'j':
                return 0xd4;
        case 'm':
                return 0xc4;
        case 'n': /* + */
                return 0xd3;
        case 'v':
                return 0xc7;
        case 'w':
                return 0xd7;
        default:
                return ch;
        }
}

static char *tty3270_add_attributes(struct tty3270 *tp, struct tty3270_line *line,
                                    struct tty3270_attribute *attr, char *cp, int lineno)
{
        const unsigned char colors[16] = {
                [0] = TAC_DEFAULT,
                [1] = TAC_RED,
                [2] = TAC_GREEN,
                [3] = TAC_YELLOW,
                [4] = TAC_BLUE,
                [5] = TAC_PINK,
                [6] = TAC_TURQ,
                [7] = TAC_WHITE,
                [9] = TAC_DEFAULT
        };

        const unsigned char highlights[8] = {
                [TTY3270_HIGHLIGHT_BLINK] = TAX_BLINK,
                [TTY3270_HIGHLIGHT_REVERSE] = TAX_REVER,
                [TTY3270_HIGHLIGHT_UNDERSCORE] = TAX_UNDER,
        };

        struct tty3270_cell *cell;
        int c, i;

        cp = tty3270_add_ba(tp, cp, TO_SBA, 0, lineno);

        for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
                if (cell->attributes.highlight != attr->highlight) {
                        attr->highlight = cell->attributes.highlight;
                        cp = tty3270_add_sa(tp, cp, TAT_EXTHI, highlights[attr->highlight]);
                }
                if (cell->attributes.f_color != attr->f_color) {
                        attr->f_color = cell->attributes.f_color;
                        cp = tty3270_add_sa(tp, cp, TAT_FGCOLOR, colors[attr->f_color]);
                }
                if (cell->attributes.b_color != attr->b_color) {
                        attr->b_color = cell->attributes.b_color;
                        cp = tty3270_add_sa(tp, cp, TAT_BGCOLOR, colors[attr->b_color]);
                }
                c = cell->character;
                if (cell->attributes.alternate_charset)
                        cp = tty3270_add_ge(tp, cp, tty3270_graphics_translate(tp, c));
                else
                        *cp++ = tp->view.ascebc[c];
        }
        return cp;
}

static void tty3270_reset_attributes(struct tty3270_attribute *attr)
{
        attr->highlight = TAX_RESET;
        attr->f_color = TAC_RESET;
        attr->b_color = TAC_RESET;
}

/*
 * Convert a tty3270_line to a 3270 data fragment usable for output.
 */
static unsigned int tty3270_convert_line(struct tty3270 *tp, struct tty3270_line *line, int lineno)
{
        struct tty3270_attribute attr;
        int flen;
        char *cp;

        /* Determine how long the fragment will be. */
        flen = tty3270_required_length(tp, line);
        if (flen > PAGE_SIZE)
                return 0;
        /* Write 3270 data fragment. */
        tty3270_reset_attributes(&attr);
        cp = tty3270_add_attributes(tp, line, &attr, tp->converted_line, lineno);
        cp = tty3270_add_reset_attributes(tp, line, cp, &attr, lineno);
        return cp - (char *)tp->converted_line;
}

static void tty3270_update_lines_visible(struct tty3270 *tp, struct raw3270_request *rq)
{
        struct tty3270_line *line;
        int len, i;

        for (i = 0; i < tty3270_tty_rows(tp); i++) {
                line = tty3270_get_view_line(tp, i);
                if (!line->dirty)
                        continue;
                len = tty3270_convert_line(tp, line, i);
                if (raw3270_request_add_data(rq, tp->converted_line, len))
                        break;
                line->dirty = 0;
        }
        if (i == tty3270_tty_rows(tp)) {
                for (i = 0; i < tp->allocated_lines; i++)
                        tp->screen[i].dirty = 0;
                tp->update_flags &= ~TTY_UPDATE_LINES;
        }
}

static void tty3270_update_lines_all(struct tty3270 *tp, struct raw3270_request *rq)
{
        struct tty3270_line *line;
        char buf[4];
        int len, i;

        for (i = 0; i < tp->allocated_lines; i++) {
                line = tty3270_get_write_line(tp, i + tp->cy + 1);
                if (!line->dirty)
                        continue;
                len = tty3270_convert_line(tp, line, tp->oops_line);
                if (raw3270_request_add_data(rq, tp->converted_line, len))
                        break;
                line->dirty = 0;
                if (++tp->oops_line >= tty3270_tty_rows(tp))
                        tp->oops_line = 0;
        }

        if (i == tp->allocated_lines) {
                if (tp->oops_line < tty3270_tty_rows(tp)) {
                        tty3270_add_ra(tp, buf, 0, tty3270_tty_rows(tp), 0);
                        if (raw3270_request_add_data(rq, buf, sizeof(buf)))
                                return;
                }
                tp->update_flags &= ~TTY_UPDATE_LINES;
        }
}

/*
 * Update 3270 display.
 */
static void tty3270_update(struct timer_list *t)
{
        struct tty3270 *tp = timer_container_of(tp, t, timer);
        struct raw3270_request *wrq;
        u8 cmd = TC_WRITE;
        int rc, len;

        wrq = xchg(&tp->write, NULL);
        if (!wrq) {
                tty3270_set_timer(tp, 1);
                return;
        }

        spin_lock_irq(&tp->view.lock);
        if (tp->update_flags == TTY_UPDATE_ALL)
                cmd = TC_EWRITEA;

        raw3270_request_set_cmd(wrq, cmd);
        raw3270_request_add_data(wrq, &tp->wcc, 1);
        tp->wcc = TW_NONE;

        /*
         * Update status line.
         */
        if (tp->update_flags & TTY_UPDATE_STATUS) {
                len = tty3270_add_status(tp);
                if (raw3270_request_add_data(wrq, tp->converted_line, len) == 0)
                        tp->update_flags &= ~TTY_UPDATE_STATUS;
        }

        /*
         * Write input line.
         */
        if (tp->update_flags & TTY_UPDATE_INPUT) {
                len = tty3270_add_prompt(tp);
                if (raw3270_request_add_data(wrq, tp->converted_line, len) == 0)
                        tp->update_flags &= ~TTY_UPDATE_INPUT;
        }

        if (tp->update_flags & TTY_UPDATE_LINES) {
                if (oops_in_progress)
                        tty3270_update_lines_all(tp, wrq);
                else
                        tty3270_update_lines_visible(tp, wrq);
        }

        wrq->callback = tty3270_write_callback;
        rc = raw3270_start(&tp->view, wrq);
        if (rc == 0) {
                if (tp->update_flags)
                        tty3270_set_timer(tp, 1);
        } else {
                raw3270_request_reset(wrq);
                xchg(&tp->write, wrq);
        }
        spin_unlock_irq(&tp->view.lock);
}

/*
 * Command recalling.
 */
static void tty3270_rcl_add(struct tty3270 *tp, char *input, int len)
{
        char *p;

        if (len <= 0)
                return;
        p = tp->rcl_lines[tp->rcl_write_index++];
        tp->rcl_write_index &= TTY3270_RECALL_SIZE - 1;
        memcpy(p, input, len);
        p[len] = '\0';
        tp->rcl_read_index = tp->rcl_write_index;
}

static void tty3270_rcl_backward(struct kbd_data *kbd)
{
        struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);
        int i = 0;

        spin_lock_irq(&tp->view.lock);
        if (tp->inattr == TF_INPUT) {
                do {
                        tp->rcl_read_index--;
                        tp->rcl_read_index &= TTY3270_RECALL_SIZE - 1;
                } while (!*tp->rcl_lines[tp->rcl_read_index] &&
                         i++ < TTY3270_RECALL_SIZE - 1);
                tty3270_update_prompt(tp, tp->rcl_lines[tp->rcl_read_index]);
        }
        spin_unlock_irq(&tp->view.lock);
}

/*
 * Deactivate tty view.
 */
static void tty3270_exit_tty(struct kbd_data *kbd)
{
        struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);

        raw3270_deactivate_view(&tp->view);
}

static void tty3270_redraw(struct tty3270 *tp)
{
        int i;

        for (i = 0; i < tty3270_tty_rows(tp); i++)
                tty3270_get_view_line(tp, i)->dirty = 1;
        tp->update_flags = TTY_UPDATE_ALL;
        tty3270_set_timer(tp, 1);
}

/*
 * Scroll forward in history.
 */
static void tty3270_scroll_forward(struct kbd_data *kbd)
{
        struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);

        spin_lock_irq(&tp->view.lock);

        if (tp->nr_up >= tty3270_tty_rows(tp))
                tp->nr_up -= tty3270_tty_rows(tp) / 2;
        else
                tp->nr_up = 0;
        tty3270_redraw(tp);
        spin_unlock_irq(&tp->view.lock);
}

/*
 * Scroll backward in history.
 */
static void tty3270_scroll_backward(struct kbd_data *kbd)
{
        struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);

        spin_lock_irq(&tp->view.lock);
        tp->nr_up += tty3270_tty_rows(tp) / 2;
        if (tp->nr_up > tp->allocated_lines - tty3270_tty_rows(tp))
                tp->nr_up = tp->allocated_lines - tty3270_tty_rows(tp);
        tty3270_redraw(tp);
        spin_unlock_irq(&tp->view.lock);
}

/*
 * Pass input line to tty.
 */
static void tty3270_read_tasklet(unsigned long data)
{
        struct raw3270_request *rrq = (struct raw3270_request *)data;
        static char kreset_data = TW_KR;
        struct tty3270 *tp = container_of(rrq->view, struct tty3270, view);
        char *input;
        int len;

        spin_lock_irq(&tp->view.lock);
        /*
         * Two AID keys are special: For 0x7d (enter) the input line
         * has to be emitted to the tty and for 0x6d the screen
         * needs to be redrawn.
         */
        input = NULL;
        len = 0;
        switch (tp->input[0]) {
        case AID_ENTER:
                /* Enter: write input to tty. */
                input = tp->input + 6;
                len = tty3270_input_size(tp->view.cols) - 6 - rrq->rescnt;
                if (tp->inattr != TF_INPUTN)
                        tty3270_rcl_add(tp, input, len);
                if (tp->nr_up > 0)
                        tp->nr_up = 0;
                /* Clear input area. */
                tty3270_update_prompt(tp, "");
                tty3270_set_timer(tp, 1);
                break;
        case AID_CLEAR:
                /* Display has been cleared. Redraw. */
                tp->update_flags = TTY_UPDATE_ALL;
                tty3270_set_timer(tp, 1);
                if (!list_empty(&tp->readpartreq->list))
                        break;
                raw3270_start_request(&tp->view, tp->readpartreq, TC_WRITESF,
                                      (char *)sfq_read_partition, sizeof(sfq_read_partition));
                break;
        case AID_READ_PARTITION:
                raw3270_read_modified_cb(tp->readpartreq, tp->input);
                break;
        default:
                break;
        }
        spin_unlock_irq(&tp->view.lock);

        /* Start keyboard reset command. */
        raw3270_start_request(&tp->view, tp->kreset, TC_WRITE, &kreset_data, 1);

        while (len-- > 0)
                kbd_keycode(tp->kbd, *input++);
        /* Emit keycode for AID byte. */
        kbd_keycode(tp->kbd, 256 + tp->input[0]);

        raw3270_request_reset(rrq);
        xchg(&tp->read, rrq);
        raw3270_put_view(&tp->view);
}

/*
 * Read request completion callback.
 */
static void tty3270_read_callback(struct raw3270_request *rq, void *data)
{
        struct tty3270 *tp = container_of(rq->view, struct tty3270, view);

        raw3270_get_view(rq->view);
        /* Schedule tasklet to pass input to tty. */
        tasklet_schedule(&tp->readlet);
}

/*
 * Issue a read request. Call with device lock.
 */
static void tty3270_issue_read(struct tty3270 *tp, int lock)
{
        struct raw3270_request *rrq;
        int rc;

        rrq = xchg(&tp->read, NULL);
        if (!rrq)
                /* Read already scheduled. */
                return;
        rrq->callback = tty3270_read_callback;
        rrq->callback_data = tp;
        raw3270_request_set_cmd(rrq, TC_READMOD);
        raw3270_request_set_data(rrq, tp->input, tty3270_input_size(tp->view.cols));
        /* Issue the read modified request. */
        if (lock)
                rc = raw3270_start(&tp->view, rrq);
        else
                rc = raw3270_start_irq(&tp->view, rrq);
        if (rc) {
                raw3270_request_reset(rrq);
                xchg(&tp->read, rrq);
        }
}

/*
 * Hang up the tty
 */
static void tty3270_hangup_tasklet(unsigned long data)
{
        struct tty3270 *tp = (struct tty3270 *)data;

        tty_port_tty_hangup(&tp->port, true);
        raw3270_put_view(&tp->view);
}

/*
 * Switch to the tty view.
 */
static int tty3270_activate(struct raw3270_view *view)
{
        struct tty3270 *tp = container_of(view, struct tty3270, view);

        tp->update_flags = TTY_UPDATE_ALL;
        tty3270_set_timer(tp, 1);
        return 0;
}

static void tty3270_deactivate(struct raw3270_view *view)
{
        struct tty3270 *tp = container_of(view, struct tty3270, view);

        timer_delete(&tp->timer);
}

static void tty3270_irq(struct tty3270 *tp, struct raw3270_request *rq, struct irb *irb)
{
        /* Handle ATTN. Schedule tasklet to read aid. */
        if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION) {
                if (!tp->throttle)
                        tty3270_issue_read(tp, 0);
                else
                        tp->attn = 1;
        }

        if (rq) {
                if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) {
                        rq->rc = -EIO;
                        raw3270_get_view(&tp->view);
                        tasklet_schedule(&tp->hanglet);
                } else {
                        /* Normal end. Copy residual count. */
                        rq->rescnt = irb->scsw.cmd.count;
                }
        } else if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) {
                /* Interrupt without an outstanding request -> update all */
                tp->update_flags = TTY_UPDATE_ALL;
                tty3270_set_timer(tp, 1);
        }
}

/*
 * Allocate tty3270 structure.
 */
static struct tty3270 *tty3270_alloc_view(void)
{
        struct tty3270 *tp;

        tp = kzalloc_obj(*tp);
        if (!tp)
                goto out_err;

        tp->write = raw3270_request_alloc(TTY3270_OUTPUT_BUFFER_SIZE);
        if (IS_ERR(tp->write))
                goto out_tp;
        tp->read = raw3270_request_alloc(0);
        if (IS_ERR(tp->read))
                goto out_write;
        tp->kreset = raw3270_request_alloc(1);
        if (IS_ERR(tp->kreset))
                goto out_read;
        tp->readpartreq = raw3270_request_alloc(sizeof(sfq_read_partition));
        if (IS_ERR(tp->readpartreq))
                goto out_reset;
        tp->kbd = kbd_alloc();
        if (!tp->kbd)
                goto out_readpartreq;

        tty_port_init(&tp->port);
        timer_setup(&tp->timer, tty3270_update, 0);
        tasklet_init(&tp->readlet, tty3270_read_tasklet,
                     (unsigned long)tp->read);
        tasklet_init(&tp->hanglet, tty3270_hangup_tasklet,
                     (unsigned long)tp);
        return tp;

out_readpartreq:
        raw3270_request_free(tp->readpartreq);
out_reset:
        raw3270_request_free(tp->kreset);
out_read:
        raw3270_request_free(tp->read);
out_write:
        raw3270_request_free(tp->write);
out_tp:
        kfree(tp);
out_err:
        return ERR_PTR(-ENOMEM);
}

/*
 * Free tty3270 structure.
 */
static void tty3270_free_view(struct tty3270 *tp)
{
        kbd_free(tp->kbd);
        raw3270_request_free(tp->kreset);
        raw3270_request_free(tp->read);
        raw3270_request_free(tp->write);
        free_page((unsigned long)tp->converted_line);
        tty_port_destroy(&tp->port);
        kfree(tp);
}

/*
 * Allocate tty3270 screen.
 */
static struct tty3270_line *tty3270_alloc_screen(struct tty3270 *tp, unsigned int rows,
                                                 unsigned int cols, int *allocated_out)
{
        struct tty3270_line *screen;
        int allocated, lines;

        allocated = __roundup_pow_of_two(rows) * TTY3270_SCREEN_PAGES;
        screen = kzalloc_objs(struct tty3270_line, allocated);
        if (!screen)
                goto out_err;
        for (lines = 0; lines < allocated; lines++) {
                screen[lines].cells = kzalloc_objs(struct tty3270_cell, cols);
                if (!screen[lines].cells)
                        goto out_screen;
        }
        *allocated_out = allocated;
        return screen;
out_screen:
        while (lines--)
                kfree(screen[lines].cells);
        kfree(screen);
out_err:
        return ERR_PTR(-ENOMEM);
}

static char **tty3270_alloc_recall(int cols)
{
        char **lines;
        int i;

        lines = kmalloc_array(TTY3270_RECALL_SIZE, sizeof(char *), GFP_KERNEL);
        if (!lines)
                return NULL;
        for (i = 0; i < TTY3270_RECALL_SIZE; i++) {
                lines[i] = kcalloc(1, tty3270_input_size(cols) + 1, GFP_KERNEL);
                if (!lines[i])
                        break;
        }

        if (i == TTY3270_RECALL_SIZE)
                return lines;

        while (i--)
                kfree(lines[i]);
        kfree(lines);
        return NULL;
}

static void tty3270_free_recall(char **lines)
{
        int i;

        for (i = 0; i < TTY3270_RECALL_SIZE; i++)
                kfree(lines[i]);
        kfree(lines);
}

/*
 * Free tty3270 screen.
 */
static void tty3270_free_screen(struct tty3270_line *screen, int old_lines)
{
        int lines;

        for (lines = 0; lines < old_lines; lines++)
                kfree(screen[lines].cells);
        kfree(screen);
}

/*
 * Resize tty3270 screen
 */
static void tty3270_resize(struct raw3270_view *view,
                           int new_model, int new_rows, int new_cols,
                           int old_model, int old_rows, int old_cols)
{
        struct tty3270 *tp = container_of(view, struct tty3270, view);
        struct tty3270_line *screen, *oscreen;
        char **old_rcl_lines, **new_rcl_lines;
        char *old_prompt, *new_prompt;
        char *old_input, *new_input;
        size_t prompt_sz;
        int new_allocated, old_allocated = tp->allocated_lines;

        if (old_model == new_model &&
            old_cols == new_cols &&
            old_rows == new_rows) {
                spin_lock_irq(&tp->view.lock);
                tty3270_redraw(tp);
                spin_unlock_irq(&tp->view.lock);
                return;
        }

        prompt_sz = tty3270_input_size(new_cols);
        new_input = kzalloc(prompt_sz, GFP_KERNEL | GFP_DMA);
        if (!new_input)
                return;
        new_prompt = kzalloc(prompt_sz, GFP_KERNEL);
        if (!new_prompt)
                goto out_input;
        screen = tty3270_alloc_screen(tp, new_rows, new_cols, &new_allocated);
        if (IS_ERR(screen))
                goto out_prompt;
        new_rcl_lines = tty3270_alloc_recall(new_cols);
        if (!new_rcl_lines)
                goto out_screen;

        /* Switch to new output size */
        spin_lock_irq(&tp->view.lock);
        tty3270_blank_screen(tp);
        oscreen = tp->screen;
        tp->screen = screen;
        tp->allocated_lines = new_allocated;
        tp->view.rows = new_rows;
        tp->view.cols = new_cols;
        tp->view.model = new_model;
        tp->update_flags = TTY_UPDATE_ALL;
        old_input = tp->input;
        old_prompt = tp->prompt;
        old_rcl_lines = tp->rcl_lines;
        tp->input = new_input;
        tp->prompt = new_prompt;
        tp->prompt_sz = prompt_sz;
        tp->rcl_lines = new_rcl_lines;
        tp->rcl_read_index = 0;
        tp->rcl_write_index = 0;
        spin_unlock_irq(&tp->view.lock);
        tty3270_free_screen(oscreen, old_allocated);
        kfree(old_input);
        kfree(old_prompt);
        tty3270_free_recall(old_rcl_lines);
        tty3270_set_timer(tp, 1);
        /* Inform the tty layer about new size */
        scoped_guard(tty_port_tty, &tp->port) {
                struct winsize ws = {
                        .ws_row = tty3270_tty_rows(tp),
                        .ws_col = tp->view.cols,
                };
                tty_do_resize(scoped_tty(), &ws);
        }
        return;
out_screen:
        tty3270_free_screen(screen, new_rows);
out_prompt:
        kfree(new_prompt);
out_input:
        kfree(new_input);
}

/*
 * Unlink tty3270 data structure from tty.
 */
static void tty3270_release(struct raw3270_view *view)
{
        struct tty3270 *tp = container_of(view, struct tty3270, view);
        struct tty_struct *tty = tty_port_tty_get(&tp->port);

        if (tty) {
                tty->driver_data = NULL;
                tty_port_tty_set(&tp->port, NULL);
                tty_hangup(tty);
                raw3270_put_view(&tp->view);
                tty_kref_put(tty);
        }
}

/*
 * Free tty3270 data structure
 */
static void tty3270_free(struct raw3270_view *view)
{
        struct tty3270 *tp = container_of(view, struct tty3270, view);

        timer_delete_sync(&tp->timer);
        tty3270_free_screen(tp->screen, tp->allocated_lines);
        free_page((unsigned long)tp->converted_line);
        kfree(tp->input);
        kfree(tp->prompt);
        tty3270_free_view(tp);
}

/*
 * Delayed freeing of tty3270 views.
 */
static void tty3270_del_views(void)
{
        int i;

        for (i = RAW3270_FIRSTMINOR; i <= tty3270_max_index; i++) {
                struct raw3270_view *view = raw3270_find_view(&tty3270_fn, i);

                if (!IS_ERR(view))
                        raw3270_del_view(view);
        }
}

static struct raw3270_fn tty3270_fn = {
        .activate = tty3270_activate,
        .deactivate = tty3270_deactivate,
        .intv = (void *)tty3270_irq,
        .release = tty3270_release,
        .free = tty3270_free,
        .resize = tty3270_resize
};

static int
tty3270_create_view(int index, struct tty3270 **newtp)
{
        struct tty3270 *tp;
        size_t prompt_sz;
        int rc;

        if (tty3270_max_index < index + 1)
                tty3270_max_index = index + 1;

        /* Allocate tty3270 structure on first open. */
        tp = tty3270_alloc_view();
        if (IS_ERR(tp))
                return PTR_ERR(tp);

        rc = raw3270_add_view(&tp->view, &tty3270_fn,
                              index + RAW3270_FIRSTMINOR,
                              RAW3270_VIEW_LOCK_IRQ);
        if (rc)
                goto out_free_view;

        tp->screen = tty3270_alloc_screen(tp, tp->view.rows, tp->view.cols,
                                          &tp->allocated_lines);
        if (IS_ERR(tp->screen)) {
                rc = PTR_ERR(tp->screen);
                goto out_put_view;
        }

        tp->converted_line = (void *)__get_free_page(GFP_KERNEL);
        if (!tp->converted_line) {
                rc = -ENOMEM;
                goto out_free_screen;
        }

        prompt_sz = tty3270_input_size(tp->view.cols);
        tp->input = kzalloc(prompt_sz, GFP_KERNEL | GFP_DMA);
        if (!tp->input) {
                rc = -ENOMEM;
                goto out_free_converted_line;
        }

        tp->prompt = kzalloc(prompt_sz, GFP_KERNEL);
        if (!tp->prompt) {
                rc = -ENOMEM;
                goto out_free_input;
        }
        tp->prompt_sz = prompt_sz;

        tp->rcl_lines = tty3270_alloc_recall(tp->view.cols);
        if (!tp->rcl_lines) {
                rc = -ENOMEM;
                goto out_free_prompt;
        }

        /* Create blank line for every line in the tty output area. */
        tty3270_blank_screen(tp);

        tp->kbd->port = &tp->port;
        tp->kbd->fn_handler[KVAL(K_INCRCONSOLE)] = tty3270_exit_tty;
        tp->kbd->fn_handler[KVAL(K_SCROLLBACK)] = tty3270_scroll_backward;
        tp->kbd->fn_handler[KVAL(K_SCROLLFORW)] = tty3270_scroll_forward;
        tp->kbd->fn_handler[KVAL(K_CONS)] = tty3270_rcl_backward;
        kbd_ascebc(tp->kbd, tp->view.ascebc);

        raw3270_activate_view(&tp->view);
        raw3270_put_view(&tp->view);
        *newtp = tp;
        return 0;

out_free_prompt:
        kfree(tp->prompt);
out_free_input:
        kfree(tp->input);
out_free_converted_line:
        free_page((unsigned long)tp->converted_line);
out_free_screen:
        tty3270_free_screen(tp->screen, tp->view.rows);
out_put_view:
        raw3270_put_view(&tp->view);
        raw3270_del_view(&tp->view);
out_free_view:
        tty3270_free_view(tp);
        return rc;
}

/*
 * This routine is called whenever a 3270 tty is opened first time.
 */
static int
tty3270_install(struct tty_driver *driver, struct tty_struct *tty)
{
        struct raw3270_view *view;
        struct tty3270 *tp;
        int rc;

        /* Check if the tty3270 is already there. */
        view = raw3270_find_view(&tty3270_fn, tty->index + RAW3270_FIRSTMINOR);
        if (IS_ERR(view)) {
                rc = tty3270_create_view(tty->index, &tp);
                if (rc)
                        return rc;
        } else {
                tp = container_of(view, struct tty3270, view);
                tty->driver_data = tp;
                tp->inattr = TF_INPUT;
        }

        tty->winsize.ws_row = tty3270_tty_rows(tp);
        tty->winsize.ws_col = tp->view.cols;
        rc = tty_port_install(&tp->port, driver, tty);
        if (rc) {
                raw3270_put_view(&tp->view);
                return rc;
        }
        tty->driver_data = tp;
        return 0;
}

/*
 * This routine is called whenever a 3270 tty is opened.
 */
static int tty3270_open(struct tty_struct *tty, struct file *filp)
{
        struct tty3270 *tp = tty->driver_data;
        struct tty_port *port = &tp->port;

        port->count++;
        tty_port_tty_set(port, tty);
        return 0;
}

/*
 * This routine is called when the 3270 tty is closed. We wait
 * for the remaining request to be completed. Then we clean up.
 */
static void tty3270_close(struct tty_struct *tty, struct file *filp)
{
        struct tty3270 *tp = tty->driver_data;

        if (tty->count > 1)
                return;
        if (tp)
                tty_port_tty_set(&tp->port, NULL);
}

static void tty3270_cleanup(struct tty_struct *tty)
{
        struct tty3270 *tp = tty->driver_data;

        if (tp) {
                tty->driver_data = NULL;
                raw3270_put_view(&tp->view);
        }
}

/*
 * We always have room.
 */
static unsigned int tty3270_write_room(struct tty_struct *tty)
{
        return INT_MAX;
}

/*
 * Insert character into the screen at the current position with the
 * current color and highlight. This function does NOT do cursor movement.
 */
static void tty3270_put_character(struct tty3270 *tp, u8 ch)
{
        struct tty3270_line *line;
        struct tty3270_cell *cell;

        line = tty3270_get_write_line(tp, tp->cy);
        if (line->len <= tp->cx) {
                while (line->len < tp->cx) {
                        cell = line->cells + line->len;
                        cell->character = ' ';
                        cell->attributes = tp->attributes;
                        line->len++;
                }
                line->len++;
        }
        cell = line->cells + tp->cx;
        cell->character = ch;
        cell->attributes = tp->attributes;
        line->dirty = 1;
}

/*
 * Do carriage return.
 */
static void tty3270_cr(struct tty3270 *tp)
{
        tp->cx = 0;
}

/*
 * Do line feed.
 */
static void tty3270_lf(struct tty3270 *tp)
{
        struct tty3270_line *line;
        int i;

        if (tp->cy < tty3270_tty_rows(tp) - 1) {
                tp->cy++;
        } else {
                tp->line_view_start = tty3270_line_increment(tp, tp->line_view_start, 1);
                tp->line_write_start = tty3270_line_increment(tp, tp->line_write_start, 1);
                for (i = 0; i < tty3270_tty_rows(tp); i++)
                        tty3270_get_view_line(tp, i)->dirty = 1;
        }

        line = tty3270_get_write_line(tp, tp->cy);
        line->len = 0;
        line->dirty = 1;
}

static void tty3270_ri(struct tty3270 *tp)
{
        if (tp->cy > 0)
                tp->cy--;
}

static void tty3270_reset_cell(struct tty3270 *tp, struct tty3270_cell *cell)
{
        cell->character = ' ';
        tty3270_reset_attributes(&cell->attributes);
}

/*
 * Insert characters at current position.
 */
static void tty3270_insert_characters(struct tty3270 *tp, int n)
{
        struct tty3270_line *line;
        int k;

        line = tty3270_get_write_line(tp, tp->cy);
        while (line->len < tp->cx)
                tty3270_reset_cell(tp, &line->cells[line->len++]);
        if (n > tp->view.cols - tp->cx)
                n = tp->view.cols - tp->cx;
        k = min_t(int, line->len - tp->cx, tp->view.cols - tp->cx - n);
        while (k--)
                line->cells[tp->cx + n + k] = line->cells[tp->cx + k];
        line->len += n;
        if (line->len > tp->view.cols)
                line->len = tp->view.cols;
        while (n-- > 0) {
                line->cells[tp->cx + n].character = ' ';
                line->cells[tp->cx + n].attributes = tp->attributes;
        }
}

/*
 * Delete characters at current position.
 */
static void tty3270_delete_characters(struct tty3270 *tp, int n)
{
        struct tty3270_line *line;
        int i;

        line = tty3270_get_write_line(tp, tp->cy);
        if (line->len <= tp->cx)
                return;
        if (line->len - tp->cx <= n) {
                line->len = tp->cx;
                return;
        }
        for (i = tp->cx; i + n < line->len; i++)
                line->cells[i] = line->cells[i + n];
        line->len -= n;
}

/*
 * Erase characters at current position.
 */
static void tty3270_erase_characters(struct tty3270 *tp, int n)
{
        struct tty3270_line *line;
        struct tty3270_cell *cell;

        line = tty3270_get_write_line(tp, tp->cy);
        while (line->len > tp->cx && n-- > 0) {
                cell = line->cells + tp->cx++;
                tty3270_reset_cell(tp, cell);
        }
        tp->cx += n;
        tp->cx = min_t(int, tp->cx, tp->view.cols - 1);
}

/*
 * Erase line, 3 different cases:
 *  Esc [ 0 K   Erase from current position to end of line inclusive
 *  Esc [ 1 K   Erase from beginning of line to current position inclusive
 *  Esc [ 2 K   Erase entire line (without moving cursor)
 */
static void tty3270_erase_line(struct tty3270 *tp, int mode)
{
        struct tty3270_line *line;
        struct tty3270_cell *cell;
        int i, start, end;

        line = tty3270_get_write_line(tp, tp->cy);

        switch (mode) {
        case 0:
                start = tp->cx;
                end = tp->view.cols;
                break;
        case 1:
                start = 0;
                end = tp->cx;
                break;
        case 2:
                start = 0;
                end = tp->view.cols;
                break;
        default:
                return;
        }

        for (i = start; i < end; i++) {
                cell = line->cells + i;
                tty3270_reset_cell(tp, cell);
                cell->attributes.b_color = tp->attributes.b_color;
        }

        if (line->len <= end)
                line->len = end;
}

/*
 * Erase display, 3 different cases:
 *  Esc [ 0 J   Erase from current position to bottom of screen inclusive
 *  Esc [ 1 J   Erase from top of screen to current position inclusive
 *  Esc [ 2 J   Erase entire screen (without moving the cursor)
 */
static void tty3270_erase_display(struct tty3270 *tp, int mode)
{
        struct tty3270_line *line;
        int i, start, end;

        switch (mode) {
        case 0:
                tty3270_erase_line(tp, 0);
                start = tp->cy + 1;
                end = tty3270_tty_rows(tp);
                break;
        case 1:
                start = 0;
                end = tp->cy;
                tty3270_erase_line(tp, 1);
                break;
        case 2:
                start = 0;
                end = tty3270_tty_rows(tp);
                break;
        default:
                return;
        }
        for (i = start; i < end; i++) {
                line = tty3270_get_write_line(tp, i);
                line->len = 0;
                line->dirty = 1;
        }
}

/*
 * Set attributes found in an escape sequence.
 *  Esc [ <attr> ; <attr> ; ... m
 */
static void tty3270_set_attributes(struct tty3270 *tp)
{
        int i, attr;

        for (i = 0; i <= tp->esc_npar; i++) {
                attr = tp->esc_par[i];
                switch (attr) {
                case 0:         /* Reset */
                        tty3270_reset_attributes(&tp->attributes);
                        break;
                /* Highlight. */
                case 4:         /* Start underlining. */
                        tp->attributes.highlight = TTY3270_HIGHLIGHT_UNDERSCORE;
                        break;
                case 5:         /* Start blink. */
                        tp->attributes.highlight = TTY3270_HIGHLIGHT_BLINK;
                        break;
                case 7:         /* Start reverse. */
                        tp->attributes.highlight = TTY3270_HIGHLIGHT_REVERSE;
                        break;
                case 24:        /* End underlining */
                        tp->attributes.highlight &= ~TTY3270_HIGHLIGHT_UNDERSCORE;
                        break;
                case 25:        /* End blink. */
                        tp->attributes.highlight &= ~TTY3270_HIGHLIGHT_BLINK;
                        break;
                case 27:        /* End reverse. */
                        tp->attributes.highlight &= ~TTY3270_HIGHLIGHT_REVERSE;
                        break;
                /* Foreground color. */
                case 30:        /* Black */
                case 31:        /* Red */
                case 32:        /* Green */
                case 33:        /* Yellow */
                case 34:        /* Blue */
                case 35:        /* Magenta */
                case 36:        /* Cyan */
                case 37:        /* White */
                case 39:        /* Black */
                        tp->attributes.f_color = attr - 30;
                        break;
                /* Background color. */
                case 40:        /* Black */
                case 41:        /* Red */
                case 42:        /* Green */
                case 43:        /* Yellow */
                case 44:        /* Blue */
                case 45:        /* Magenta */
                case 46:        /* Cyan */
                case 47:        /* White */
                case 49:        /* Black */
                        tp->attributes.b_color = attr - 40;
                        break;
                }
        }
}

static inline int tty3270_getpar(struct tty3270 *tp, int ix)
{
        return (tp->esc_par[ix] > 0) ? tp->esc_par[ix] : 1;
}

static void tty3270_goto_xy(struct tty3270 *tp, int cx, int cy)
{
        struct tty3270_line *line;
        struct tty3270_cell *cell;
        int max_cx = max(0, cx);
        int max_cy = max(0, cy);

        tp->cx = min_t(int, tp->view.cols - 1, max_cx);
        line = tty3270_get_write_line(tp, tp->cy);
        while (line->len < tp->cx) {
                cell = line->cells + line->len;
                cell->character = ' ';
                cell->attributes = tp->attributes;
                line->len++;
        }
        tp->cy = min_t(int, tty3270_tty_rows(tp) - 1, max_cy);
}

/*
 * Process escape sequences. Known sequences:
 *  Esc 7                       Save Cursor Position
 *  Esc 8                       Restore Cursor Position
 *  Esc [ Pn ; Pn ; .. m        Set attributes
 *  Esc [ Pn ; Pn H             Cursor Position
 *  Esc [ Pn ; Pn f             Cursor Position
 *  Esc [ Pn A                  Cursor Up
 *  Esc [ Pn B                  Cursor Down
 *  Esc [ Pn C                  Cursor Forward
 *  Esc [ Pn D                  Cursor Backward
 *  Esc [ Pn G                  Cursor Horizontal Absolute
 *  Esc [ Pn X                  Erase Characters
 *  Esc [ Ps J                  Erase in Display
 *  Esc [ Ps K                  Erase in Line
 * // FIXME: add all the new ones.
 *
 *  Pn is a numeric parameter, a string of zero or more decimal digits.
 *  Ps is a selective parameter.
 */
static void tty3270_escape_sequence(struct tty3270 *tp, u8 ch)
{
        enum { ES_NORMAL, ES_ESC, ES_SQUARE, ES_PAREN, ES_GETPARS };

        if (tp->esc_state == ES_NORMAL) {
                if (ch == 0x1b)
                        /* Starting new escape sequence. */
                        tp->esc_state = ES_ESC;
                return;
        }
        if (tp->esc_state == ES_ESC) {
                tp->esc_state = ES_NORMAL;
                switch (ch) {
                case '[':
                        tp->esc_state = ES_SQUARE;
                        break;
                case '(':
                        tp->esc_state = ES_PAREN;
                        break;
                case 'E':
                        tty3270_cr(tp);
                        tty3270_lf(tp);
                        break;
                case 'M':
                        tty3270_ri(tp);
                        break;
                case 'D':
                        tty3270_lf(tp);
                        break;
                case 'Z':               /* Respond ID. */
                        kbd_puts_queue(&tp->port, "\033[?6c");
                        break;
                case '7':               /* Save cursor position. */
                        tp->saved_cx = tp->cx;
                        tp->saved_cy = tp->cy;
                        tp->saved_attributes = tp->attributes;
                        break;
                case '8':               /* Restore cursor position. */
                        tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
                        tp->attributes = tp->saved_attributes;
                        break;
                case 'c':               /* Reset terminal. */
                        tp->cx = 0;
                        tp->cy = 0;
                        tp->saved_cx = 0;
                        tp->saved_cy = 0;
                        tty3270_reset_attributes(&tp->attributes);
                        tty3270_reset_attributes(&tp->saved_attributes);
                        tty3270_erase_display(tp, 2);
                        break;
                }
                return;
        }

        switch (tp->esc_state) {
        case ES_PAREN:
                tp->esc_state = ES_NORMAL;
                switch (ch) {
                case 'B':
                        tp->attributes.alternate_charset = 0;
                        break;
                case '0':
                        tp->attributes.alternate_charset = 1;
                        break;
                }
                return;
        case ES_SQUARE:
                tp->esc_state = ES_GETPARS;
                memset(tp->esc_par, 0, sizeof(tp->esc_par));
                tp->esc_npar = 0;
                tp->esc_ques = (ch == '?');
                if (tp->esc_ques)
                        return;
                fallthrough;
        case ES_GETPARS:
                if (ch == ';' && tp->esc_npar < ESCAPE_NPAR - 1) {
                        tp->esc_npar++;
                        return;
                }
                if (ch >= '0' && ch <= '9') {
                        tp->esc_par[tp->esc_npar] *= 10;
                        tp->esc_par[tp->esc_npar] += ch - '0';
                        return;
                }
                break;
        default:
                break;
        }
        tp->esc_state = ES_NORMAL;
        if (ch == 'n' && !tp->esc_ques) {
                if (tp->esc_par[0] == 5)                /* Status report. */
                        kbd_puts_queue(&tp->port, "\033[0n");
                else if (tp->esc_par[0] == 6) { /* Cursor report. */
                        char buf[40];

                        scnprintf(buf, sizeof(buf), "\033[%d;%dR", tp->cy + 1, tp->cx + 1);
                        kbd_puts_queue(&tp->port, buf);
                }
                return;
        }
        if (tp->esc_ques)
                return;
        switch (ch) {
        case 'm':
                tty3270_set_attributes(tp);
                break;
        case 'H':       /* Set cursor position. */
        case 'f':
                tty3270_goto_xy(tp, tty3270_getpar(tp, 1) - 1,
                                tty3270_getpar(tp, 0) - 1);
                break;
        case 'd':       /* Set y position. */
                tty3270_goto_xy(tp, tp->cx, tty3270_getpar(tp, 0) - 1);
                break;
        case 'A':       /* Cursor up. */
        case 'F':
                tty3270_goto_xy(tp, tp->cx, tp->cy - tty3270_getpar(tp, 0));
                break;
        case 'B':       /* Cursor down. */
        case 'e':
        case 'E':
                tty3270_goto_xy(tp, tp->cx, tp->cy + tty3270_getpar(tp, 0));
                break;
        case 'C':       /* Cursor forward. */
        case 'a':
                tty3270_goto_xy(tp, tp->cx + tty3270_getpar(tp, 0), tp->cy);
                break;
        case 'D':       /* Cursor backward. */
                tty3270_goto_xy(tp, tp->cx - tty3270_getpar(tp, 0), tp->cy);
                break;
        case 'G':       /* Set x position. */
        case '`':
                tty3270_goto_xy(tp, tty3270_getpar(tp, 0), tp->cy);
                break;
        case 'X':       /* Erase Characters. */
                tty3270_erase_characters(tp, tty3270_getpar(tp, 0));
                break;
        case 'J':       /* Erase display. */
                tty3270_erase_display(tp, tp->esc_par[0]);
                break;
        case 'K':       /* Erase line. */
                tty3270_erase_line(tp, tp->esc_par[0]);
                break;
        case 'P':       /* Delete characters. */
                tty3270_delete_characters(tp, tty3270_getpar(tp, 0));
                break;
        case '@':       /* Insert characters. */
                tty3270_insert_characters(tp, tty3270_getpar(tp, 0));
                break;
        case 's':       /* Save cursor position. */
                tp->saved_cx = tp->cx;
                tp->saved_cy = tp->cy;
                tp->saved_attributes = tp->attributes;
                break;
        case 'u':       /* Restore cursor position. */
                tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
                tp->attributes = tp->saved_attributes;
                break;
        }
}

/*
 * String write routine for 3270 ttys
 */
static void tty3270_do_write(struct tty3270 *tp, struct tty_struct *tty,
                             const u8 *buf, size_t count)
{
        int i_msg, i;

        spin_lock_irq(&tp->view.lock);
        for (i_msg = 0; !tty->flow.stopped && i_msg < count; i_msg++) {
                if (tp->esc_state != 0) {
                        /* Continue escape sequence. */
                        tty3270_escape_sequence(tp, buf[i_msg]);
                        continue;
                }

                switch (buf[i_msg]) {
                case 0x00:
                        break;
                case 0x07:              /* '\a' -- Alarm */
                        tp->wcc |= TW_PLUSALARM;
                        break;
                case 0x08:              /* Backspace. */
                        if (tp->cx > 0) {
                                tp->cx--;
                                tty3270_put_character(tp, ' ');
                        }
                        break;
                case 0x09:              /* '\t' -- Tabulate */
                        for (i = tp->cx % 8; i < 8; i++) {
                                if (tp->cx >= tp->view.cols) {
                                        tty3270_cr(tp);
                                        tty3270_lf(tp);
                                        break;
                                }
                                tty3270_put_character(tp, ' ');
                                tp->cx++;
                        }
                        break;
                case 0x0a:              /* '\n' -- New Line */
                        tty3270_cr(tp);
                        tty3270_lf(tp);
                        break;
                case 0x0c:              /* '\f' -- Form Feed */
                        tty3270_erase_display(tp, 2);
                        tp->cx = 0;
                        tp->cy = 0;
                        break;
                case 0x0d:              /* '\r' -- Carriage Return */
                        tp->cx = 0;
                        break;
                case 0x0e:
                        tp->attributes.alternate_charset = 1;
                        break;
                case 0x0f:              /* SuSE "exit alternate mode" */
                        tp->attributes.alternate_charset = 0;
                        break;
                case 0x1b:              /* Start escape sequence. */
                        tty3270_escape_sequence(tp, buf[i_msg]);
                        break;
                default:                /* Insert normal character. */
                        if (tp->cx >= tp->view.cols) {
                                tty3270_cr(tp);
                                tty3270_lf(tp);
                        }
                        tty3270_put_character(tp, buf[i_msg]);
                        tp->cx++;
                        break;
                }
        }
        /* Setup timer to update display after 1/10 second */
        tp->update_flags |= TTY_UPDATE_LINES;
        if (!timer_pending(&tp->timer))
                tty3270_set_timer(tp, msecs_to_jiffies(100));

        spin_unlock_irq(&tp->view.lock);
}

/*
 * String write routine for 3270 ttys
 */
static ssize_t tty3270_write(struct tty_struct *tty, const u8 *buf,
                             size_t count)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return 0;
        if (tp->char_count > 0) {
                tty3270_do_write(tp, tty, tp->char_buf, tp->char_count);
                tp->char_count = 0;
        }
        tty3270_do_write(tp, tty, buf, count);
        return count;
}

/*
 * Put single characters to the ttys character buffer
 */
static int tty3270_put_char(struct tty_struct *tty, u8 ch)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp || tp->char_count >= TTY3270_CHAR_BUF_SIZE)
                return 0;
        tp->char_buf[tp->char_count++] = ch;
        return 1;
}

/*
 * Flush all characters from the ttys characeter buffer put there
 * by tty3270_put_char.
 */
static void tty3270_flush_chars(struct tty_struct *tty)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return;
        if (tp->char_count > 0) {
                tty3270_do_write(tp, tty, tp->char_buf, tp->char_count);
                tp->char_count = 0;
        }
}

/*
 * Check for visible/invisible input switches
 */
static void tty3270_set_termios(struct tty_struct *tty, const struct ktermios *old)
{
        struct tty3270 *tp;
        int new;

        tp = tty->driver_data;
        if (!tp)
                return;
        spin_lock_irq(&tp->view.lock);
        if (L_ICANON(tty)) {
                new = L_ECHO(tty) ? TF_INPUT : TF_INPUTN;
                if (new != tp->inattr) {
                        tp->inattr = new;
                        tty3270_update_prompt(tp, "");
                        tty3270_set_timer(tp, 1);
                }
        }
        spin_unlock_irq(&tp->view.lock);
}

/*
 * Disable reading from a 3270 tty
 */
static void tty3270_throttle(struct tty_struct *tty)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return;
        tp->throttle = 1;
}

/*
 * Enable reading from a 3270 tty
 */
static void tty3270_unthrottle(struct tty_struct *tty)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return;
        tp->throttle = 0;
        if (tp->attn)
                tty3270_issue_read(tp, 1);
}

/*
 * Hang up the tty device.
 */
static void tty3270_hangup(struct tty_struct *tty)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return;
        spin_lock_irq(&tp->view.lock);
        tp->cx = 0;
        tp->cy = 0;
        tp->saved_cx = 0;
        tp->saved_cy = 0;
        tty3270_reset_attributes(&tp->attributes);
        tty3270_reset_attributes(&tp->saved_attributes);
        tty3270_blank_screen(tp);
        tp->update_flags = TTY_UPDATE_ALL;
        spin_unlock_irq(&tp->view.lock);
        tty3270_set_timer(tp, 1);
}

static void tty3270_wait_until_sent(struct tty_struct *tty, int timeout)
{
}

static int tty3270_ioctl(struct tty_struct *tty, unsigned int cmd,
                         unsigned long arg)
{
        struct tty3270 *tp;

        tp = tty->driver_data;
        if (!tp)
                return -ENODEV;
        if (tty_io_error(tty))
                return -EIO;
        return kbd_ioctl(tp->kbd, cmd, arg);
}

static const struct tty_operations tty3270_ops = {
        .install = tty3270_install,
        .cleanup = tty3270_cleanup,
        .open = tty3270_open,
        .close = tty3270_close,
        .write = tty3270_write,
        .put_char = tty3270_put_char,
        .flush_chars = tty3270_flush_chars,
        .write_room = tty3270_write_room,
        .throttle = tty3270_throttle,
        .unthrottle = tty3270_unthrottle,
        .hangup = tty3270_hangup,
        .wait_until_sent = tty3270_wait_until_sent,
        .ioctl = tty3270_ioctl,
        .set_termios = tty3270_set_termios
};

static void tty3270_create_cb(int minor)
{
        tty_register_device(tty3270_driver, minor - RAW3270_FIRSTMINOR, NULL);
}

static void tty3270_destroy_cb(int minor)
{
        tty_unregister_device(tty3270_driver, minor - RAW3270_FIRSTMINOR);
}

static struct raw3270_notifier tty3270_notifier = {
        .create = tty3270_create_cb,
        .destroy = tty3270_destroy_cb,
};

/*
 * 3270 tty registration code called from tty_init().
 * Most kernel services (incl. kmalloc) are available at this poimt.
 */
static int __init tty3270_init(void)
{
        struct tty_driver *driver;
        int ret;

        driver = tty_alloc_driver(RAW3270_MAXDEVS,
                                  TTY_DRIVER_REAL_RAW |
                                  TTY_DRIVER_DYNAMIC_DEV |
                                  TTY_DRIVER_RESET_TERMIOS);
        if (IS_ERR(driver))
                return PTR_ERR(driver);

        /*
         * Initialize the tty_driver structure
         * Entries in tty3270_driver that are NOT initialized:
         * proc_entry, set_termios, flush_buffer, set_ldisc, write_proc
         */
        driver->driver_name = "tty3270";
        driver->name = "3270/tty";
        driver->major = IBM_TTY3270_MAJOR;
        driver->minor_start = RAW3270_FIRSTMINOR;
        driver->name_base = RAW3270_FIRSTMINOR;
        driver->type = TTY_DRIVER_TYPE_SYSTEM;
        driver->subtype = SYSTEM_TYPE_TTY;
        driver->init_termios = tty_std_termios;
        tty_set_operations(driver, &tty3270_ops);
        ret = tty_register_driver(driver);
        if (ret) {
                tty_driver_kref_put(driver);
                return ret;
        }
        tty3270_driver = driver;
        raw3270_register_notifier(&tty3270_notifier);
        return 0;
}

static void __exit tty3270_exit(void)
{
        struct tty_driver *driver;

        raw3270_unregister_notifier(&tty3270_notifier);
        driver = tty3270_driver;
        tty3270_driver = NULL;
        tty_unregister_driver(driver);
        tty_driver_kref_put(driver);
        tty3270_del_views();
}

#if IS_ENABLED(CONFIG_TN3270_CONSOLE)

static struct tty3270 *condev;

static void
con3270_write(struct console *co, const char *str, unsigned int count)
{
        struct tty3270 *tp = co->data;
        unsigned long flags;
        u8 c;

        spin_lock_irqsave(&tp->view.lock, flags);
        while (count--) {
                c = *str++;
                if (c == 0x0a) {
                        tty3270_cr(tp);
                        tty3270_lf(tp);
                } else {
                        if (tp->cx >= tp->view.cols) {
                                tty3270_cr(tp);
                                tty3270_lf(tp);
                        }
                        tty3270_put_character(tp, c);
                        tp->cx++;
                }
        }
        spin_unlock_irqrestore(&tp->view.lock, flags);
}

static struct tty_driver *
con3270_device(struct console *c, int *index)
{
        *index = c->index;
        return tty3270_driver;
}

static void
con3270_wait_write(struct tty3270 *tp)
{
        while (!tp->write) {
                raw3270_wait_cons_dev(tp->view.dev);
                barrier();
        }
}

/*
 * The below function is called as a panic/reboot notifier before the
 * system enters a disabled, endless loop.
 *
 * Notice we must use the spin_trylock() alternative, to prevent lockups
 * in atomic context (panic routine runs with secondary CPUs, local IRQs
 * and preemption disabled).
 */
static int con3270_notify(struct notifier_block *self,
                          unsigned long event, void *data)
{
        struct tty3270 *tp;
        unsigned long flags;
        int rc;

        tp = condev;
        if (!tp->view.dev)
                return NOTIFY_DONE;
        if (!raw3270_view_lock_unavailable(&tp->view)) {
                rc = raw3270_activate_view(&tp->view);
                if (rc)
                        return NOTIFY_DONE;
        }
        if (!spin_trylock_irqsave(&tp->view.lock, flags))
                return NOTIFY_DONE;
        con3270_wait_write(tp);
        tp->nr_up = 0;
        tp->update_flags = TTY_UPDATE_ALL;
        while (tp->update_flags != 0) {
                spin_unlock_irqrestore(&tp->view.lock, flags);
                tty3270_update(&tp->timer);
                spin_lock_irqsave(&tp->view.lock, flags);
                con3270_wait_write(tp);
        }
        spin_unlock_irqrestore(&tp->view.lock, flags);
        return NOTIFY_DONE;
}

static struct notifier_block on_panic_nb = {
        .notifier_call = con3270_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

static struct notifier_block on_reboot_nb = {
        .notifier_call = con3270_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

static struct console con3270 = {
        .name    = "tty3270",
        .write   = con3270_write,
        .device  = con3270_device,
        .flags   = CON_PRINTBUFFER,
};

static int __init
con3270_init(void)
{
        struct raw3270_view *view;
        struct raw3270 *rp;
        struct tty3270 *tp;
        int rc;

        /* Check if 3270 is to be the console */
        if (!CONSOLE_IS_3270)
                return -ENODEV;

        /* Set the console mode for VM */
        if (machine_is_vm()) {
                cpcmd("TERM CONMODE 3270", NULL, 0, NULL);
                cpcmd("TERM AUTOCR OFF", NULL, 0, NULL);
        }

        rp = raw3270_setup_console();
        if (IS_ERR(rp))
                return PTR_ERR(rp);

        /* Check if the tty3270 is already there. */
        view = raw3270_find_view(&tty3270_fn, RAW3270_FIRSTMINOR);
        if (IS_ERR(view)) {
                rc = tty3270_create_view(0, &tp);
                if (rc)
                        return rc;
        } else {
                tp = container_of(view, struct tty3270, view);
                tp->inattr = TF_INPUT;
        }
        con3270.data = tp;
        condev = tp;
        atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
        register_reboot_notifier(&on_reboot_nb);
        register_console(&con3270);
        return 0;
}
console_initcall(con3270_init);
#endif

MODULE_DESCRIPTION("IBM/3270 Driver - tty functions");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(IBM_TTY3270_MAJOR);

module_init(tty3270_init);
module_exit(tty3270_exit);