tty3270.c

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/*
 *    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 <[email protected]>
 *  -- 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/slab.h>
#include <linux/bootmem.h>
#include <linux/compat.h>

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

#include "raw3270.h"
#include "tty3270.h"
#include "keyboard.h"

#define TTY3270_CHAR_BUF_SIZE 256
#define TTY3270_OUTPUT_BUFFER_SIZE 1024
#define TTY3270_STRING_PAGES 5

struct tty_driver *tty3270_driver;
static int tty3270_max_index;

static struct raw3270_fn tty3270_fn;

struct tty3270_cell {
    unsigned char character;
    unsigned char highlight;
    unsigned char f_color;
};

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

#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;
    void **freemem_pages;       /* Array of pages used for freemem. */
    struct list_head freemem;   /* List of free memory for strings. */

    /* Output stuff. */
    struct list_head lines;     /* List of lines. */
    struct list_head update;    /* List of lines to update. */
    unsigned char wcc;      /* Write control character. */
    int nr_lines;           /* # lines in list. */
    int nr_up;          /* # lines up in history. */
    unsigned long update_flags; /* Update indication bits. */
    struct string *status;      /* Lower right of display. */
    struct raw3270_request *write;  /* Single write request. */
    struct timer_list timer;    /* Output delay timer. */

    /* Current tty screen. */
    unsigned int cx, cy;        /* Current output position. */
    unsigned int highlight;     /* Blink/reverse/underscore */
    unsigned int f_color;       /* Foreground color */
    struct tty3270_line *screen;

    /* Input stuff. */
    struct string *prompt;      /* Output string for input area. */
    struct string *input;       /* Input string for read request. */
    struct raw3270_request *read;   /* Single read request. */
    struct raw3270_request *kreset; /* Single keyboard reset request. */
    unsigned char inattr;       /* Visible/invisible input. */
    int throttle, attn;     /* tty throttle/unthrottle. */
    struct tasklet_struct readlet;  /* Tasklet to issue read request. */
    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;
    unsigned int saved_highlight, saved_f_color;

    /* Command recalling. */
    struct list_head rcl_lines; /* List of recallable lines. */
    struct list_head *rcl_walk; /* Point in rcl_lines list. */
    int rcl_nr, rcl_max;        /* Number/max number of rcl_lines. */

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

/* tty3270->update_flags. See tty3270_update for details. */
#define TTY_UPDATE_ERASE    1   /* Use EWRITEA instead of WRITE. */
#define TTY_UPDATE_LIST     2   /* Update lines in tty3270->update. */
#define TTY_UPDATE_INPUT    4   /* Update input line. */
#define TTY_UPDATE_STATUS   8   /* Update status line. */
#define TTY_UPDATE_ALL      16  /* Recreate screen. */

static void tty3270_update(struct tty3270 *);

/*
 * Setup timeout for a device. On timeout trigger an update.
 */
static void tty3270_set_timer(struct tty3270 *tp, int expires)
{
    if (expires == 0)
        del_timer(&tp->timer);
    else
        mod_timer(&tp->timer, jiffies + expires);
}

/*
 * The input line are the two last lines of the screen.
 */
static void
tty3270_update_prompt(struct tty3270 *tp, char *input, int count)
{
    struct string *line;
    unsigned int off;

    line = tp->prompt;
    if (count != 0)
        line->string[5] = TF_INMDT;
    else
        line->string[5] = tp->inattr;
    if (count > tp->view.cols * 2 - 11)
        count = tp->view.cols * 2 - 11;
    memcpy(line->string + 6, input, count);
    line->string[6 + count] = TO_IC;
    /* Clear to end of input line. */
    if (count < tp->view.cols * 2 - 11) {
        line->string[7 + count] = TO_RA;
        line->string[10 + count] = 0;
        off = tp->view.cols * tp->view.rows - 9;
        raw3270_buffer_address(tp->view.dev, line->string+count+8, off);
        line->len = 11 + count;
    } else
        line->len = 7 + count;
    tp->update_flags |= TTY_UPDATE_INPUT;
}

static void
tty3270_create_prompt(struct tty3270 *tp)
{
    static const unsigned char blueprint[] =
        { TO_SBA, 0, 0, 0x6e, TO_SF, TF_INPUT,
          /* empty input string */
          TO_IC, TO_RA, 0, 0, 0 };
    struct string *line;
    unsigned int offset;

    line = alloc_string(&tp->freemem,
                sizeof(blueprint) + tp->view.cols * 2 - 9);
    tp->prompt = line;
    tp->inattr = TF_INPUT;
    /* Copy blueprint to status line */
    memcpy(line->string, blueprint, sizeof(blueprint));
    line->len = sizeof(blueprint);
    /* Set output offsets. */
    offset = tp->view.cols * (tp->view.rows - 2);
    raw3270_buffer_address(tp->view.dev, line->string + 1, offset);
    offset = tp->view.cols * tp->view.rows - 9;
    raw3270_buffer_address(tp->view.dev, line->string + 8, offset);

    /* Allocate input string for reading. */
    tp->input = alloc_string(&tp->freemem, tp->view.cols * 2 - 9 + 6);
}

/*
 * The status line is the last line of the screen. It shows the string
 * "Running"/"Holding" in the lower right corner of the screen.
 */
static void
tty3270_update_status(struct tty3270 * tp)
{
    char *str;

    str = (tp->nr_up != 0) ? "History" : "Running";
    memcpy(tp->status->string + 8, str, 7);
    codepage_convert(tp->view.ascebc, tp->status->string + 8, 7);
    tp->update_flags |= TTY_UPDATE_STATUS;
}

static void
tty3270_create_status(struct tty3270 * tp)
{
    static const unsigned char blueprint[] =
        { TO_SBA, 0, 0, TO_SF, TF_LOG, TO_SA, TAT_COLOR, TAC_GREEN,
          0, 0, 0, 0, 0, 0, 0, TO_SF, TF_LOG, TO_SA, TAT_COLOR,
          TAC_RESET };
    struct string *line;
    unsigned int offset;

    line = alloc_string(&tp->freemem,sizeof(blueprint));
    tp->status = line;
    /* Copy blueprint to status line */
    memcpy(line->string, blueprint, sizeof(blueprint));
    /* Set address to start of status string (= last 9 characters). */
    offset = tp->view.cols * tp->view.rows - 9;
    raw3270_buffer_address(tp->view.dev, line->string + 1, offset);
}

/*
 * Set output offsets to 3270 datastream fragment of a tty string.
 * (TO_SBA offset at the start and TO_RA offset at the end of the string)
 */
static void
tty3270_update_string(struct tty3270 *tp, struct string *line, int nr)
{
    unsigned char *cp;

    raw3270_buffer_address(tp->view.dev, line->string + 1,
                   tp->view.cols * nr);
    cp = line->string + line->len - 4;
    if (*cp == TO_RA)
        raw3270_buffer_address(tp->view.dev, cp + 1,
                       tp->view.cols * (nr + 1));
}

/*
 * Rebuild update list to print all lines.
 */
static void
tty3270_rebuild_update(struct tty3270 *tp)
{
    struct string *s, *n;
    int line, nr_up;

    /* 
     * Throw away update list and create a new one,
     * containing all lines that will fit on the screen.
     */
    list_for_each_entry_safe(s, n, &tp->update, update)
        list_del_init(&s->update);
    line = tp->view.rows - 3;
    nr_up = tp->nr_up;
    list_for_each_entry_reverse(s, &tp->lines, list) {
        if (nr_up > 0) {
            nr_up--;
            continue;
        }
        tty3270_update_string(tp, s, line);
        list_add(&s->update, &tp->update);
        if (--line < 0)
            break;
    }
    tp->update_flags |= TTY_UPDATE_LIST;
}

/*
 * Alloc string for size bytes. If there is not enough room in
 * freemem, free strings until there is room.
 */
static struct string *
tty3270_alloc_string(struct tty3270 *tp, size_t size)
{
    struct string *s, *n;

    s = alloc_string(&tp->freemem, size);
    if (s)
        return s;
    list_for_each_entry_safe(s, n, &tp->lines, list) {
        BUG_ON(tp->nr_lines <= tp->view.rows - 2);
        list_del(&s->list);
        if (!list_empty(&s->update))
            list_del(&s->update);
        tp->nr_lines--;
        if (free_string(&tp->freemem, s) >= size)
            break;
    }
    s = alloc_string(&tp->freemem, size);
    BUG_ON(!s);
    if (tp->nr_up != 0 &&
        tp->nr_up + tp->view.rows - 2 >= tp->nr_lines) {
        tp->nr_up = tp->nr_lines - tp->view.rows + 2;
        tty3270_rebuild_update(tp);
        tty3270_update_status(tp);
    }
    return s;
}

/*
 * Add an empty line to the list.
 */
static void
tty3270_blank_line(struct tty3270 *tp)
{
    static const unsigned char blueprint[] =
        { TO_SBA, 0, 0, TO_SA, TAT_EXTHI, TAX_RESET,
          TO_SA, TAT_COLOR, TAC_RESET, TO_RA, 0, 0, 0 };
    struct string *s;

    s = tty3270_alloc_string(tp, sizeof(blueprint));
    memcpy(s->string, blueprint, sizeof(blueprint));
    s->len = sizeof(blueprint);
    list_add_tail(&s->list, &tp->lines);
    tp->nr_lines++;
    if (tp->nr_up != 0)
        tp->nr_up++;
}

/*
 * 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);
}

/*
 * Update 3270 display.
 */
static void
tty3270_update(struct tty3270 *tp)
{
    static char invalid_sba[2] = { 0xff, 0xff };
    struct raw3270_request *wrq;
    unsigned long updated;
    struct string *s, *n;
    char *sba, *str;
    int rc, len;

    wrq = xchg(&tp->write, 0);
    if (!wrq) {
        tty3270_set_timer(tp, 1);
        return;
    }

    spin_lock(&tp->view.lock);
    updated = 0;
    if (tp->update_flags & TTY_UPDATE_ALL) {
        tty3270_rebuild_update(tp);
        tty3270_update_status(tp);
        tp->update_flags = TTY_UPDATE_ERASE | TTY_UPDATE_LIST |
            TTY_UPDATE_INPUT | TTY_UPDATE_STATUS;
    }
    if (tp->update_flags & TTY_UPDATE_ERASE) {
        /* Use erase write alternate to erase display. */
        raw3270_request_set_cmd(wrq, TC_EWRITEA);
        updated |= TTY_UPDATE_ERASE;
    } else
        raw3270_request_set_cmd(wrq, TC_WRITE);

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

    /*
     * Update status line.
     */
    if (tp->update_flags & TTY_UPDATE_STATUS)
        if (raw3270_request_add_data(wrq, tp->status->string,
                         tp->status->len) == 0)
            updated |= TTY_UPDATE_STATUS;

    /*
     * Write input line.
     */
    if (tp->update_flags & TTY_UPDATE_INPUT)
        if (raw3270_request_add_data(wrq, tp->prompt->string,
                         tp->prompt->len) == 0)
            updated |= TTY_UPDATE_INPUT;

    sba = invalid_sba;
    
    if (tp->update_flags & TTY_UPDATE_LIST) {
        /* Write strings in the update list to the screen. */
        list_for_each_entry_safe(s, n, &tp->update, update) {
            str = s->string;
            len = s->len;
            /*
             * Skip TO_SBA at the start of the string if the
             * last output position matches the start address
             * of this line.
             */
            if (s->string[1] == sba[0] && s->string[2] == sba[1])
                str += 3, len -= 3;
            if (raw3270_request_add_data(wrq, str, len) != 0)
                break;
            list_del_init(&s->update);
            sba = s->string + s->len - 3;
        }
        if (list_empty(&tp->update))
            updated |= TTY_UPDATE_LIST;
    }
    wrq->callback = tty3270_write_callback;
    rc = raw3270_start(&tp->view, wrq);
    if (rc == 0) {
        tp->update_flags &= ~updated;
        if (tp->update_flags)
            tty3270_set_timer(tp, 1);
    } else {
        raw3270_request_reset(wrq);
        xchg(&tp->write, wrq);
    }
    spin_unlock(&tp->view.lock);
}

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

    tp->rcl_walk = NULL;
    if (len <= 0)
        return;
    if (tp->rcl_nr >= tp->rcl_max) {
        s = list_entry(tp->rcl_lines.next, struct string, list);
        list_del(&s->list);
        free_string(&tp->freemem, s);
        tp->rcl_nr--;
    }
    s = tty3270_alloc_string(tp, len);
    memcpy(s->string, input, len);
    list_add_tail(&s->list, &tp->rcl_lines);
    tp->rcl_nr++;
}

static void
tty3270_rcl_backward(struct kbd_data *kbd)
{
    struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);
    struct string *s;

    spin_lock_bh(&tp->view.lock);
    if (tp->inattr == TF_INPUT) {
        if (tp->rcl_walk && tp->rcl_walk->prev != &tp->rcl_lines)
            tp->rcl_walk = tp->rcl_walk->prev;
        else if (!list_empty(&tp->rcl_lines))
            tp->rcl_walk = tp->rcl_lines.prev;
        s = tp->rcl_walk ? 
            list_entry(tp->rcl_walk, struct string, list) : NULL;
        if (tp->rcl_walk) {
            s = list_entry(tp->rcl_walk, struct string, list);
            tty3270_update_prompt(tp, s->string, s->len);
        } else
            tty3270_update_prompt(tp, NULL, 0);
        tty3270_set_timer(tp, 1);
    }
    spin_unlock_bh(&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);
}

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

    spin_lock_bh(&tp->view.lock);
    nr_up = tp->nr_up - tp->view.rows + 2;
    if (nr_up < 0)
        nr_up = 0;
    if (nr_up != tp->nr_up) {
        tp->nr_up = nr_up;
        tty3270_rebuild_update(tp);
        tty3270_update_status(tp);
        tty3270_set_timer(tp, 1);
    }
    spin_unlock_bh(&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);
    int nr_up;

    spin_lock_bh(&tp->view.lock);
    nr_up = tp->nr_up + tp->view.rows - 2;
    if (nr_up + tp->view.rows - 2 > tp->nr_lines)
        nr_up = tp->nr_lines - tp->view.rows + 2;
    if (nr_up != tp->nr_up) {
        tp->nr_up = nr_up;
        tty3270_rebuild_update(tp);
        tty3270_update_status(tp);
        tty3270_set_timer(tp, 1);
    }
    spin_unlock_bh(&tp->view.lock);
}

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

    spin_lock_bh(&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;
    if (tp->input->string[0] == 0x7d) {
        /* Enter: write input to tty. */
        input = tp->input->string + 6;
        len = tp->input->len - 6 - rrq->rescnt;
        if (tp->inattr != TF_INPUTN)
            tty3270_rcl_add(tp, input, len);
        if (tp->nr_up > 0) {
            tp->nr_up = 0;
            tty3270_rebuild_update(tp);
            tty3270_update_status(tp);
        }
        /* Clear input area. */
        tty3270_update_prompt(tp, NULL, 0);
        tty3270_set_timer(tp, 1);
    } else if (tp->input->string[0] == 0x6d) {
        /* Display has been cleared. Redraw. */
        tp->update_flags = TTY_UPDATE_ALL;
        tty3270_set_timer(tp, 1);
    }
    spin_unlock_bh(&tp->view.lock);

    /* Start keyboard reset command. */
    raw3270_request_reset(tp->kreset);
    raw3270_request_set_cmd(tp->kreset, TC_WRITE);
    raw3270_request_add_data(tp->kreset, &kreset_data, 1);
    raw3270_start(&tp->view, tp->kreset);

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

/*
 * 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);

    del_timer(&tp->timer);
}

static int
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;
        else
            /* Normal end. Copy residual count. */
            rq->rescnt = irb->scsw.cmd.count;
    }
    return RAW3270_IO_DONE;
}

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

    tp = kzalloc(sizeof(struct tty3270), GFP_KERNEL);
    if (!tp)
        goto out_err;
    tp->freemem_pages =
        kmalloc(sizeof(void *) * TTY3270_STRING_PAGES, GFP_KERNEL);
    if (!tp->freemem_pages)
        goto out_tp;
    INIT_LIST_HEAD(&tp->freemem);
    INIT_LIST_HEAD(&tp->lines);
    INIT_LIST_HEAD(&tp->update);
    INIT_LIST_HEAD(&tp->rcl_lines);
    tp->rcl_max = 20;
    tty_port_init(&tp->port);
    setup_timer(&tp->timer, (void (*)(unsigned long)) tty3270_update,
            (unsigned long) tp);
    tasklet_init(&tp->readlet,
             (void (*)(unsigned long)) tty3270_read_tasklet,
             (unsigned long) tp->read);

    for (pages = 0; pages < TTY3270_STRING_PAGES; pages++) {
        tp->freemem_pages[pages] = (void *)
            __get_free_pages(GFP_KERNEL|GFP_DMA, 0);
        if (!tp->freemem_pages[pages])
            goto out_pages;
        add_string_memory(&tp->freemem,
                  tp->freemem_pages[pages], PAGE_SIZE);
    }
    tp->write = raw3270_request_alloc(TTY3270_OUTPUT_BUFFER_SIZE);
    if (IS_ERR(tp->write))
        goto out_pages;
    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->kbd = kbd_alloc();
    if (!tp->kbd)
        goto out_reset;
    return tp;

out_reset:
    raw3270_request_free(tp->kreset);
out_read:
    raw3270_request_free(tp->read);
out_write:
    raw3270_request_free(tp->write);
out_pages:
    while (pages--)
        free_pages((unsigned long) tp->freemem_pages[pages], 0);
    kfree(tp->freemem_pages);
out_tp:
    kfree(tp);
out_err:
    return ERR_PTR(-ENOMEM);
}

/*
 * Free tty3270 structure.
 */
static void
tty3270_free_view(struct tty3270 *tp)
{
    int pages;

    del_timer_sync(&tp->timer);
    kbd_free(tp->kbd);
    raw3270_request_free(tp->kreset);
    raw3270_request_free(tp->read);
    raw3270_request_free(tp->write);
    for (pages = 0; pages < TTY3270_STRING_PAGES; pages++)
        free_pages((unsigned long) tp->freemem_pages[pages], 0);
    kfree(tp->freemem_pages);
    kfree(tp);
}

/*
 * Allocate tty3270 screen.
 */
static int
tty3270_alloc_screen(struct tty3270 *tp)
{
    unsigned long size;
    int lines;

    size = sizeof(struct tty3270_line) * (tp->view.rows - 2);
    tp->screen = kzalloc(size, GFP_KERNEL);
    if (!tp->screen)
        goto out_err;
    for (lines = 0; lines < tp->view.rows - 2; lines++) {
        size = sizeof(struct tty3270_cell) * tp->view.cols;
        tp->screen[lines].cells = kzalloc(size, GFP_KERNEL);
        if (!tp->screen[lines].cells)
            goto out_screen;
    }
    return 0;
out_screen:
    while (lines--)
        kfree(tp->screen[lines].cells);
    kfree(tp->screen);
out_err:
    return -ENOMEM;
}

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

    for (lines = 0; lines < tp->view.rows - 2; lines++)
        kfree(tp->screen[lines].cells);
    kfree(tp->screen);
}

/*
 * 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);
    tty3270_free_screen(tp);
    tty3270_free_view(tp);
}

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

    for (i = 0; i < tty3270_max_index; i++) {
        struct raw3270_view *view =
            raw3270_find_view(&tty3270_fn, i + RAW3270_FIRSTMINOR);
        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
};

/*
 * 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 i, rc;

    /* Check if the tty3270 is already there. */
    view = raw3270_find_view(&tty3270_fn,
                  tty->index + RAW3270_FIRSTMINOR);
    if (!IS_ERR(view)) {
        tp = container_of(view, struct tty3270, view);
        tty->driver_data = tp;
        tty->winsize.ws_row = tp->view.rows - 2;
        tty->winsize.ws_col = tp->view.cols;
        tty->low_latency = 0;
        /* why to reassign? */
        tty_port_tty_set(&tp->port, tty);
        tp->inattr = TF_INPUT;
        return tty_port_install(&tp->port, driver, tty);
    }
    if (tty3270_max_index < tty->index + 1)
        tty3270_max_index = tty->index + 1;

    /* Quick exit if there is no device for tty->index. */
    if (PTR_ERR(view) == -ENODEV)
        return -ENODEV;

    /* 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,
                  tty->index + RAW3270_FIRSTMINOR);
    if (rc) {
        tty3270_free_view(tp);
        return rc;
    }

    rc = tty3270_alloc_screen(tp);
    if (rc) {
        raw3270_put_view(&tp->view);
        raw3270_del_view(&tp->view);
        return rc;
    }

    tty_port_tty_set(&tp->port, tty);
    tty->low_latency = 0;
    tty->winsize.ws_row = tp->view.rows - 2;
    tty->winsize.ws_col = tp->view.cols;

    tty3270_create_prompt(tp);
    tty3270_create_status(tp);
    tty3270_update_status(tp);

    /* Create blank line for every line in the tty output area. */
    for (i = 0; i < tp->view.rows - 2; i++)
        tty3270_blank_line(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);

    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 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->driver_data = NULL;
        tty_port_tty_set(&tp->port, NULL);
    }
}

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

    if (tp)
        raw3270_put_view(&tp->view);
}

/*
 * We always have room.
 */
static 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, char ch)
{
    struct tty3270_line *line;
    struct tty3270_cell *cell;

    line = tp->screen + tp->cy;
    if (line->len <= tp->cx) {
        while (line->len < tp->cx) {
            cell = line->cells + line->len;
            cell->character = tp->view.ascebc[' '];
            cell->highlight = tp->highlight;
            cell->f_color = tp->f_color;
            line->len++;
        }
        line->len++;
    }
    cell = line->cells + tp->cx;
    cell->character = tp->view.ascebc[(unsigned int) ch];
    cell->highlight = tp->highlight;
    cell->f_color = tp->f_color;
}

/*
 * Convert a tty3270_line to a 3270 data fragment usable for output.
 */
static void
tty3270_convert_line(struct tty3270 *tp, int line_nr)
{
    struct tty3270_line *line;
    struct tty3270_cell *cell;
    struct string *s, *n;
    unsigned char highlight;
    unsigned char f_color;
    char *cp;
    int flen, i;

    /* Determine how long the fragment will be. */
    flen = 3;       /* Prefix (TO_SBA). */
    line = tp->screen + line_nr;
    flen += line->len;
    highlight = TAX_RESET;
    f_color = TAC_RESET;
    for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
        if (cell->highlight != highlight) {
            flen += 3;  /* TO_SA to switch highlight. */
            highlight = cell->highlight;
        }
        if (cell->f_color != f_color) {
            flen += 3;  /* TO_SA to switch color. */
            f_color = cell->f_color;
        }
    }
    if (highlight != TAX_RESET)
        flen += 3;  /* TO_SA to reset hightlight. */
    if (f_color != TAC_RESET)
        flen += 3;  /* TO_SA to reset color. */
    if (line->len < tp->view.cols)
        flen += 4;  /* Postfix (TO_RA). */

    /* Find the line in the list. */
    i = tp->view.rows - 2 - line_nr;
    list_for_each_entry_reverse(s, &tp->lines, list)
        if (--i <= 0)
            break;
    /*
     * Check if the line needs to get reallocated.
     */
    if (s->len != flen) {
        /* Reallocate string. */
        n = tty3270_alloc_string(tp, flen);
        list_add(&n->list, &s->list);
        list_del_init(&s->list);
        if (!list_empty(&s->update))
            list_del_init(&s->update);
        free_string(&tp->freemem, s);
        s = n;
    }

    /* Write 3270 data fragment. */
    cp = s->string;
    *cp++ = TO_SBA;
    *cp++ = 0;
    *cp++ = 0;

    highlight = TAX_RESET;
    f_color = TAC_RESET;
    for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
        if (cell->highlight != highlight) {
            *cp++ = TO_SA;
            *cp++ = TAT_EXTHI;
            *cp++ = cell->highlight;
            highlight = cell->highlight;
        }
        if (cell->f_color != f_color) {
            *cp++ = TO_SA;
            *cp++ = TAT_COLOR;
            *cp++ = cell->f_color;
            f_color = cell->f_color;
        }
        *cp++ = cell->character;
    }
    if (highlight != TAX_RESET) {
        *cp++ = TO_SA;
        *cp++ = TAT_EXTHI;
        *cp++ = TAX_RESET;
    }
    if (f_color != TAC_RESET) {
        *cp++ = TO_SA;
        *cp++ = TAT_COLOR;
        *cp++ = TAC_RESET;
    }
    if (line->len < tp->view.cols) {
        *cp++ = TO_RA;
        *cp++ = 0;
        *cp++ = 0;
        *cp++ = 0;
    }

    if (tp->nr_up + line_nr < tp->view.rows - 2) {
        /* Line is currently visible on screen. */
        tty3270_update_string(tp, s, line_nr);
        /* Add line to update list. */
        if (list_empty(&s->update)) {
            list_add_tail(&s->update, &tp->update);
            tp->update_flags |= TTY_UPDATE_LIST;
        }
    }
}

/*
 * 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 temp;
    int i;

    tty3270_convert_line(tp, tp->cy);
    if (tp->cy < tp->view.rows - 3) {
        tp->cy++;
        return;
    }
    /* Last line just filled up. Add new, blank line. */
    tty3270_blank_line(tp);
    temp = tp->screen[0];
    temp.len = 0;
    for (i = 0; i < tp->view.rows - 3; i++)
        tp->screen[i] = tp->screen[i+1];
    tp->screen[tp->view.rows - 3] = temp;
    tty3270_rebuild_update(tp);
}

static void
tty3270_ri(struct tty3270 *tp)
{
    if (tp->cy > 0) {
        tty3270_convert_line(tp, tp->cy);
        tp->cy--;
    }
}

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

    line = tp->screen + tp->cy;
    while (line->len < tp->cx) {
        line->cells[line->len].character = tp->view.ascebc[' '];
        line->cells[line->len].highlight = TAX_RESET;
        line->cells[line->len].f_color = TAC_RESET;
        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 = tp->view.ascebc[' '];
        line->cells[tp->cx + n].highlight = tp->highlight;
        line->cells[tp->cx + n].f_color = tp->f_color;
    }
}

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

    line = tp->screen + 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 = tp->screen + tp->cy;
    while (line->len > tp->cx && n-- > 0) {
        cell = line->cells + tp->cx++;
        cell->character = ' ';
        cell->highlight = TAX_RESET;
        cell->f_color = TAC_RESET;
    }
    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;

    line = tp->screen + tp->cy;
    if (mode == 0)
        line->len = tp->cx;
    else if (mode == 1) {
        for (i = 0; i < tp->cx; i++) {
            cell = line->cells + i;
            cell->character = ' ';
            cell->highlight = TAX_RESET;
            cell->f_color = TAC_RESET;
        }
        if (line->len <= tp->cx)
            line->len = tp->cx + 1;
    } else if (mode == 2)
        line->len = 0;
    tty3270_convert_line(tp, tp->cy);
}

/*
 * 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)
{
    int i;

    if (mode == 0) {
        tty3270_erase_line(tp, 0);
        for (i = tp->cy + 1; i < tp->view.rows - 2; i++) {
            tp->screen[i].len = 0;
            tty3270_convert_line(tp, i);
        }
    } else if (mode == 1) {
        for (i = 0; i < tp->cy; i++) {
            tp->screen[i].len = 0;
            tty3270_convert_line(tp, i);
        }
        tty3270_erase_line(tp, 1);
    } else if (mode == 2) {
        for (i = 0; i < tp->view.rows - 2; i++) {
            tp->screen[i].len = 0;
            tty3270_convert_line(tp, i);
        }
    }
    tty3270_rebuild_update(tp);
}

/*
 * Set attributes found in an escape sequence.
 *  Esc [ <attr> ; <attr> ; ... m
 */
static void
tty3270_set_attributes(struct tty3270 *tp)
{
    static unsigned char f_colors[] = {
        TAC_DEFAULT, TAC_RED, TAC_GREEN, TAC_YELLOW, TAC_BLUE,
        TAC_PINK, TAC_TURQ, TAC_WHITE, 0, TAC_DEFAULT
    };
    int i, attr;

    for (i = 0; i <= tp->esc_npar; i++) {
        attr = tp->esc_par[i];
        switch (attr) {
        case 0:     /* Reset */
            tp->highlight = TAX_RESET;
            tp->f_color = TAC_RESET;
            break;
        /* Highlight. */
        case 4:     /* Start underlining. */
            tp->highlight = TAX_UNDER;
            break;
        case 5:     /* Start blink. */
            tp->highlight = TAX_BLINK;
            break;
        case 7:     /* Start reverse. */
            tp->highlight = TAX_REVER;
            break;
        case 24:    /* End underlining */
            if (tp->highlight == TAX_UNDER)
                tp->highlight = TAX_RESET;
            break;
        case 25:    /* End blink. */
            if (tp->highlight == TAX_BLINK)
                tp->highlight = TAX_RESET;
            break;
        case 27:    /* End reverse. */
            if (tp->highlight == TAX_REVER)
                tp->highlight = TAX_RESET;
            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->f_color = f_colors[attr - 30];
            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)
{
    int max_cx = max(0, cx);
    int max_cy = max(0, cy);

    tp->cx = min_t(int, tp->view.cols - 1, max_cx);
    cy = min_t(int, tp->view.rows - 3, max_cy);
    if (cy != tp->cy) {
        tty3270_convert_line(tp, tp->cy);
        tp->cy = 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, char ch)
{
    enum { ESnormal, ESesc, ESsquare, ESgetpars };

    if (tp->esc_state == ESnormal) {
        if (ch == 0x1b)
            /* Starting new escape sequence. */
            tp->esc_state = ESesc;
        return;
    }
    if (tp->esc_state == ESesc) {
        tp->esc_state = ESnormal;
        switch (ch) {
        case '[':
            tp->esc_state = ESsquare;
            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_highlight = tp->highlight;
            tp->saved_f_color = tp->f_color;
            break;
        case '8':       /* Restore cursor position. */
            tty3270_convert_line(tp, tp->cy);
            tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
            tp->highlight = tp->saved_highlight;
            tp->f_color = tp->saved_f_color;
            break;
        case 'c':       /* Reset terminal. */
            tp->cx = tp->saved_cx = 0;
            tp->cy = tp->saved_cy = 0;
            tp->highlight = tp->saved_highlight = TAX_RESET;
            tp->f_color = tp->saved_f_color = TAC_RESET;
            tty3270_erase_display(tp, 2);
            break;
        }
        return;
    }
    if (tp->esc_state == ESsquare) {
        tp->esc_state = ESgetpars;
        memset(tp->esc_par, 0, sizeof(tp->esc_par));
        tp->esc_npar = 0;
        tp->esc_ques = (ch == '?');
        if (tp->esc_ques)
            return;
    }
    if (tp->esc_state == ESgetpars) {
        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;
        }
    }
    tp->esc_state = ESnormal;
    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];
            sprintf(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_highlight = tp->highlight;
        tp->saved_f_color = tp->f_color;
        break;
    case 'u':   /* Restore cursor position. */
        tty3270_convert_line(tp, tp->cy);
        tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
        tp->highlight = tp->saved_highlight;
        tp->f_color = tp->saved_f_color;
        break;
    }
}

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

    spin_lock_bh(&tp->view.lock);
    for (i_msg = 0; !tty->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 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 = tp->cy = 0;
            break;
        case 0x0d:      /* '\r' -- Carriage Return */
            tp->cx = 0;
            break;
        case 0x0f:      /* SuSE "exit alternate mode" */
            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;
        }
    }
    /* Convert current line to 3270 data fragment. */
    tty3270_convert_line(tp, tp->cy);

    /* Setup timer to update display after 1/10 second */
    if (!timer_pending(&tp->timer))
        tty3270_set_timer(tp, HZ/10);

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

/*
 * String write routine for 3270 ttys
 */
static int
tty3270_write(struct tty_struct * tty,
          const unsigned char *buf, int 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, unsigned char 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;
    }
}

/*
 * Returns the number of characters in the output buffer. This is
 * used in tty_wait_until_sent to wait until all characters have
 * appeared on the screen.
 */
static int
tty3270_chars_in_buffer(struct tty_struct *tty)
{
    return 0;
}

static void
tty3270_flush_buffer(struct tty_struct *tty)
{
}

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

    tp = tty->driver_data;
    if (!tp)
        return;
    spin_lock_bh(&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, NULL, 0);
            tty3270_set_timer(tp, 1);
        }
    }
    spin_unlock_bh(&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)
{
    // FIXME: implement
}

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->flags & (1 << TTY_IO_ERROR))
        return -EIO;
    return kbd_ioctl(tp->kbd, cmd, arg);
}

#ifdef CONFIG_COMPAT
static long tty3270_compat_ioctl(struct tty_struct *tty,
                 unsigned int cmd, unsigned long arg)
{
    struct tty3270 *tp;

    tp = tty->driver_data;
    if (!tp)
        return -ENODEV;
    if (tty->flags & (1 << TTY_IO_ERROR))
        return -EIO;
    return kbd_ioctl(tp->kbd, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static const struct tty_operations tty3270_ops = {
    .install = tty3270_install,
    .cleanup = tty3270_cleanup,
    .close = tty3270_close,
    .write = tty3270_write,
    .put_char = tty3270_put_char,
    .flush_chars = tty3270_flush_chars,
    .write_room = tty3270_write_room,
    .chars_in_buffer = tty3270_chars_in_buffer,
    .flush_buffer = tty3270_flush_buffer,
    .throttle = tty3270_throttle,
    .unthrottle = tty3270_unthrottle,
    .hangup = tty3270_hangup,
    .wait_until_sent = tty3270_wait_until_sent,
    .ioctl = tty3270_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = tty3270_compat_ioctl,
#endif
    .set_termios = tty3270_set_termios
};

/*
 * 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 = alloc_tty_driver(RAW3270_MAXDEVS);
    if (!driver)
        return -ENOMEM;

    /*
     * 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 = "ttyTUB";
    driver->name = "ttyTUB";
    driver->major = IBM_TTY3270_MAJOR;
    driver->minor_start = RAW3270_FIRSTMINOR;
    driver->type = TTY_DRIVER_TYPE_SYSTEM;
    driver->subtype = SYSTEM_TYPE_TTY;
    driver->init_termios = tty_std_termios;
    driver->flags = TTY_DRIVER_RESET_TERMIOS;
    tty_set_operations(driver, &tty3270_ops);
    ret = tty_register_driver(driver);
    if (ret) {
        put_tty_driver(driver);
        return ret;
    }
    tty3270_driver = driver;
    return 0;
}

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

    driver = tty3270_driver;
    tty3270_driver = NULL;
    tty_unregister_driver(driver);
    put_tty_driver(driver);
    tty3270_del_views();
}

MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(IBM_TTY3270_MAJOR);

module_init(tty3270_init);
module_exit(tty3270_exit);