sclp_tty.c

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/*
 *    SCLP line mode terminal driver.
 *
 *  S390 version
 *    Copyright IBM Corp. 1999
 *    Author(s): Martin Peschke <[email protected]>
 *       Martin Schwidefsky <[email protected]>
 */

#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/gfp.h>
#include <asm/uaccess.h>

#include "ctrlchar.h"
#include "sclp.h"
#include "sclp_rw.h"
#include "sclp_tty.h"

/*
 * size of a buffer that collects single characters coming in
 * via sclp_tty_put_char()
 */
#define SCLP_TTY_BUF_SIZE 512

/*
 * There is exactly one SCLP terminal, so we can keep things simple
 * and allocate all variables statically.
 */

/* Lock to guard over changes to global variables. */
static spinlock_t sclp_tty_lock;
/* List of free pages that can be used for console output buffering. */
static struct list_head sclp_tty_pages;
/* List of full struct sclp_buffer structures ready for output. */
static struct list_head sclp_tty_outqueue;
/* Counter how many buffers are emitted. */
static int sclp_tty_buffer_count;
/* Pointer to current console buffer. */
static struct sclp_buffer *sclp_ttybuf;
/* Timer for delayed output of console messages. */
static struct timer_list sclp_tty_timer;

static struct tty_port sclp_port;
static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
static unsigned short int sclp_tty_chars_count;

struct tty_driver *sclp_tty_driver;

static int sclp_tty_tolower;
static int sclp_tty_columns = 80;

#define SPACES_PER_TAB 8
#define CASE_DELIMITER 0x6c /* to separate upper and lower case (% in EBCDIC) */

/* This routine is called whenever we try to open a SCLP terminal. */
static int
sclp_tty_open(struct tty_struct *tty, struct file *filp)
{
    tty_port_tty_set(&sclp_port, tty);
    tty->driver_data = NULL;
    tty->low_latency = 0;
    return 0;
}

/* This routine is called when the SCLP terminal is closed. */
static void
sclp_tty_close(struct tty_struct *tty, struct file *filp)
{
    if (tty->count > 1)
        return;
    tty_port_tty_set(&sclp_port, NULL);
}

/*
 * This routine returns the numbers of characters the tty driver
 * will accept for queuing to be written.  This number is subject
 * to change as output buffers get emptied, or if the output flow
 * control is acted. This is not an exact number because not every
 * character needs the same space in the sccb. The worst case is
 * a string of newlines. Every newlines creates a new mto which
 * needs 8 bytes.
 */
static int
sclp_tty_write_room (struct tty_struct *tty)
{
    unsigned long flags;
    struct list_head *l;
    int count;

    spin_lock_irqsave(&sclp_tty_lock, flags);
    count = 0;
    if (sclp_ttybuf != NULL)
        count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct mto);
    list_for_each(l, &sclp_tty_pages)
        count += NR_EMPTY_MTO_PER_SCCB;
    spin_unlock_irqrestore(&sclp_tty_lock, flags);
    return count;
}

static void
sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
{
    struct tty_struct *tty;
    unsigned long flags;
    void *page;

    do {
        page = sclp_unmake_buffer(buffer);
        spin_lock_irqsave(&sclp_tty_lock, flags);
        /* Remove buffer from outqueue */
        list_del(&buffer->list);
        sclp_tty_buffer_count--;
        list_add_tail((struct list_head *) page, &sclp_tty_pages);
        /* Check if there is a pending buffer on the out queue. */
        buffer = NULL;
        if (!list_empty(&sclp_tty_outqueue))
            buffer = list_entry(sclp_tty_outqueue.next,
                        struct sclp_buffer, list);
        spin_unlock_irqrestore(&sclp_tty_lock, flags);
    } while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
    /* check if the tty needs a wake up call */
    tty = tty_port_tty_get(&sclp_port);
    if (tty != NULL) {
        tty_wakeup(tty);
        tty_kref_put(tty);
    }
}

static inline void
__sclp_ttybuf_emit(struct sclp_buffer *buffer)
{
    unsigned long flags;
    int count;
    int rc;

    spin_lock_irqsave(&sclp_tty_lock, flags);
    list_add_tail(&buffer->list, &sclp_tty_outqueue);
    count = sclp_tty_buffer_count++;
    spin_unlock_irqrestore(&sclp_tty_lock, flags);
    if (count)
        return;
    rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
    if (rc)
        sclp_ttybuf_callback(buffer, rc);
}

/*
 * When this routine is called from the timer then we flush the
 * temporary write buffer.
 */
static void
sclp_tty_timeout(unsigned long data)
{
    unsigned long flags;
    struct sclp_buffer *buf;

    spin_lock_irqsave(&sclp_tty_lock, flags);
    buf = sclp_ttybuf;
    sclp_ttybuf = NULL;
    spin_unlock_irqrestore(&sclp_tty_lock, flags);

    if (buf != NULL) {
        __sclp_ttybuf_emit(buf);
    }
}

/*
 * Write a string to the sclp tty.
 */
static int sclp_tty_write_string(const unsigned char *str, int count, int may_fail)
{
    unsigned long flags;
    void *page;
    int written;
    int overall_written;
    struct sclp_buffer *buf;

    if (count <= 0)
        return 0;
    overall_written = 0;
    spin_lock_irqsave(&sclp_tty_lock, flags);
    do {
        /* Create a sclp output buffer if none exists yet */
        if (sclp_ttybuf == NULL) {
            while (list_empty(&sclp_tty_pages)) {
                spin_unlock_irqrestore(&sclp_tty_lock, flags);
                if (may_fail)
                    goto out;
                else
                    sclp_sync_wait();
                spin_lock_irqsave(&sclp_tty_lock, flags);
            }
            page = sclp_tty_pages.next;
            list_del((struct list_head *) page);
            sclp_ttybuf = sclp_make_buffer(page, sclp_tty_columns,
                               SPACES_PER_TAB);
        }
        /* try to write the string to the current output buffer */
        written = sclp_write(sclp_ttybuf, str, count);
        overall_written += written;
        if (written == count)
            break;
        /*
         * Not all characters could be written to the current
         * output buffer. Emit the buffer, create a new buffer
         * and then output the rest of the string.
         */
        buf = sclp_ttybuf;
        sclp_ttybuf = NULL;
        spin_unlock_irqrestore(&sclp_tty_lock, flags);
        __sclp_ttybuf_emit(buf);
        spin_lock_irqsave(&sclp_tty_lock, flags);
        str += written;
        count -= written;
    } while (count > 0);
    /* Setup timer to output current console buffer after 1/10 second */
    if (sclp_ttybuf && sclp_chars_in_buffer(sclp_ttybuf) &&
        !timer_pending(&sclp_tty_timer)) {
        init_timer(&sclp_tty_timer);
        sclp_tty_timer.function = sclp_tty_timeout;
        sclp_tty_timer.data = 0UL;
        sclp_tty_timer.expires = jiffies + HZ/10;
        add_timer(&sclp_tty_timer);
    }
    spin_unlock_irqrestore(&sclp_tty_lock, flags);
out:
    return overall_written;
}

/*
 * This routine is called by the kernel to write a series of characters to the
 * tty device. The characters may come from user space or kernel space. This
 * routine will return the number of characters actually accepted for writing.
 */
static int
sclp_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
    if (sclp_tty_chars_count > 0) {
        sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
        sclp_tty_chars_count = 0;
    }
    return sclp_tty_write_string(buf, count, 1);
}

/*
 * This routine is called by the kernel to write a single character to the tty
 * device. If the kernel uses this routine, it must call the flush_chars()
 * routine (if defined) when it is done stuffing characters into the driver.
 *
 * Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
 * If the given character is a '\n' the contents of the SCLP write buffer
 * - including previous characters from sclp_tty_put_char() and strings from
 * sclp_write() without final '\n' - will be written.
 */
static int
sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
{
    sclp_tty_chars[sclp_tty_chars_count++] = ch;
    if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
        sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
        sclp_tty_chars_count = 0;
    }
    return 1;
}

/*
 * This routine is called by the kernel after it has written a series of
 * characters to the tty device using put_char().
 */
static void
sclp_tty_flush_chars(struct tty_struct *tty)
{
    if (sclp_tty_chars_count > 0) {
        sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
        sclp_tty_chars_count = 0;
    }
}

/*
 * This routine returns the number of characters in the write buffer of the
 * SCLP driver. The provided number includes all characters that are stored
 * in the SCCB (will be written next time the SCLP is not busy) as well as
 * characters in the write buffer (will not be written as long as there is a
 * final line feed missing).
 */
static int
sclp_tty_chars_in_buffer(struct tty_struct *tty)
{
    unsigned long flags;
    struct list_head *l;
    struct sclp_buffer *t;
    int count;

    spin_lock_irqsave(&sclp_tty_lock, flags);
    count = 0;
    if (sclp_ttybuf != NULL)
        count = sclp_chars_in_buffer(sclp_ttybuf);
    list_for_each(l, &sclp_tty_outqueue) {
        t = list_entry(l, struct sclp_buffer, list);
        count += sclp_chars_in_buffer(t);
    }
    spin_unlock_irqrestore(&sclp_tty_lock, flags);
    return count;
}

/*
 * removes all content from buffers of low level driver
 */
static void
sclp_tty_flush_buffer(struct tty_struct *tty)
{
    if (sclp_tty_chars_count > 0) {
        sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
        sclp_tty_chars_count = 0;
    }
}

/*
 * push input to tty
 */
static void
sclp_tty_input(unsigned char* buf, unsigned int count)
{
    struct tty_struct *tty = tty_port_tty_get(&sclp_port);
    unsigned int cchar;

    /*
     * If this tty driver is currently closed
     * then throw the received input away.
     */
    if (tty == NULL)
        return;
    cchar = ctrlchar_handle(buf, count, tty);
    switch (cchar & CTRLCHAR_MASK) {
    case CTRLCHAR_SYSRQ:
        break;
    case CTRLCHAR_CTRL:
        tty_insert_flip_char(tty, cchar, TTY_NORMAL);
        tty_flip_buffer_push(tty);
        break;
    case CTRLCHAR_NONE:
        /* send (normal) input to line discipline */
        if (count < 2 ||
            (strncmp((const char *) buf + count - 2, "^n", 2) &&
             strncmp((const char *) buf + count - 2, "\252n", 2))) {
            /* add the auto \n */
            tty_insert_flip_string(tty, buf, count);
            tty_insert_flip_char(tty, '\n', TTY_NORMAL);
        } else
            tty_insert_flip_string(tty, buf, count - 2);
        tty_flip_buffer_push(tty);
        break;
    }
    tty_kref_put(tty);
}

/*
 * get a EBCDIC string in upper/lower case,
 * find out characters in lower/upper case separated by a special character,
 * modifiy original string,
 * returns length of resulting string
 */
static int sclp_switch_cases(unsigned char *buf, int count)
{
    unsigned char *ip, *op;
    int toggle;

    /* initially changing case is off */
    toggle = 0;
    ip = op = buf;
    while (count-- > 0) {
        /* compare with special character */
        if (*ip == CASE_DELIMITER) {
            /* followed by another special character? */
            if (count && ip[1] == CASE_DELIMITER) {
                /*
                 * ... then put a single copy of the special
                 * character to the output string
                 */
                *op++ = *ip++;
                count--;
            } else
                /*
                 * ... special character follower by a normal
                 * character toggles the case change behaviour
                 */
                toggle = ~toggle;
            /* skip special character */
            ip++;
        } else
            /* not the special character */
            if (toggle)
                /* but case switching is on */
                if (sclp_tty_tolower)
                    /* switch to uppercase */
                    *op++ = _ebc_toupper[(int) *ip++];
                else
                    /* switch to lowercase */
                    *op++ = _ebc_tolower[(int) *ip++];
            else
                /* no case switching, copy the character */
                *op++ = *ip++;
    }
    /* return length of reformatted string. */
    return op - buf;
}

static void sclp_get_input(struct gds_subvector *sv)
{
    unsigned char *str;
    int count;

    str = (unsigned char *) (sv + 1);
    count = sv->length - sizeof(*sv);
    if (sclp_tty_tolower)
        EBC_TOLOWER(str, count);
    count = sclp_switch_cases(str, count);
    /* convert EBCDIC to ASCII (modify original input in SCCB) */
    sclp_ebcasc_str(str, count);

    /* transfer input to high level driver */
    sclp_tty_input(str, count);
}

static inline void sclp_eval_selfdeftextmsg(struct gds_subvector *sv)
{
    void *end;

    end = (void *) sv + sv->length;
    for (sv = sv + 1; (void *) sv < end; sv = (void *) sv + sv->length)
        if (sv->key == 0x30)
            sclp_get_input(sv);
}

static inline void sclp_eval_textcmd(struct gds_vector *v)
{
    struct gds_subvector *sv;
    void *end;

    end = (void *) v + v->length;
    for (sv = (struct gds_subvector *) (v + 1);
         (void *) sv < end; sv = (void *) sv + sv->length)
        if (sv->key == GDS_KEY_SELFDEFTEXTMSG)
            sclp_eval_selfdeftextmsg(sv);

}

static inline void sclp_eval_cpmsu(struct gds_vector *v)
{
    void *end;

    end = (void *) v + v->length;
    for (v = v + 1; (void *) v < end; v = (void *) v + v->length)
        if (v->gds_id == GDS_ID_TEXTCMD)
            sclp_eval_textcmd(v);
}


static inline void sclp_eval_mdsmu(struct gds_vector *v)
{
    v = sclp_find_gds_vector(v + 1, (void *) v + v->length, GDS_ID_CPMSU);
    if (v)
        sclp_eval_cpmsu(v);
}

static void sclp_tty_receiver(struct evbuf_header *evbuf)
{
    struct gds_vector *v;

    v = sclp_find_gds_vector(evbuf + 1, (void *) evbuf + evbuf->length,
                 GDS_ID_MDSMU);
    if (v)
        sclp_eval_mdsmu(v);
}

static void
sclp_tty_state_change(struct sclp_register *reg)
{
}

static struct sclp_register sclp_input_event =
{
    .receive_mask = EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK,
    .state_change_fn = sclp_tty_state_change,
    .receiver_fn = sclp_tty_receiver
};

static const struct tty_operations sclp_ops = {
    .open = sclp_tty_open,
    .close = sclp_tty_close,
    .write = sclp_tty_write,
    .put_char = sclp_tty_put_char,
    .flush_chars = sclp_tty_flush_chars,
    .write_room = sclp_tty_write_room,
    .chars_in_buffer = sclp_tty_chars_in_buffer,
    .flush_buffer = sclp_tty_flush_buffer,
};

static int __init
sclp_tty_init(void)
{
    struct tty_driver *driver;
    void *page;
    int i;
    int rc;

    if (!CONSOLE_IS_SCLP)
        return 0;
    driver = alloc_tty_driver(1);
    if (!driver)
        return -ENOMEM;

    rc = sclp_rw_init();
    if (rc) {
        put_tty_driver(driver);
        return rc;
    }
    /* Allocate pages for output buffering */
    INIT_LIST_HEAD(&sclp_tty_pages);
    for (i = 0; i < MAX_KMEM_PAGES; i++) {
        page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
        if (page == NULL) {
            put_tty_driver(driver);
            return -ENOMEM;
        }
        list_add_tail((struct list_head *) page, &sclp_tty_pages);
    }
    INIT_LIST_HEAD(&sclp_tty_outqueue);
    spin_lock_init(&sclp_tty_lock);
    init_timer(&sclp_tty_timer);
    sclp_ttybuf = NULL;
    sclp_tty_buffer_count = 0;
    if (MACHINE_IS_VM) {
        /*
         * save 4 characters for the CPU number
         * written at start of each line by VM/CP
         */
        sclp_tty_columns = 76;
        /* case input lines to lowercase */
        sclp_tty_tolower = 1;
    }
    sclp_tty_chars_count = 0;
    tty_port_init(&sclp_port);

    rc = sclp_register(&sclp_input_event);
    if (rc) {
        put_tty_driver(driver);
        return rc;
    }

    driver->driver_name = "sclp_line";
    driver->name = "sclp_line";
    driver->major = TTY_MAJOR;
    driver->minor_start = 64;
    driver->type = TTY_DRIVER_TYPE_SYSTEM;
    driver->subtype = SYSTEM_TYPE_TTY;
    driver->init_termios = tty_std_termios;
    driver->init_termios.c_iflag = IGNBRK | IGNPAR;
    driver->init_termios.c_oflag = ONLCR | XTABS;
    driver->init_termios.c_lflag = ISIG | ECHO;
    driver->flags = TTY_DRIVER_REAL_RAW;
    tty_set_operations(driver, &sclp_ops);
    tty_port_link_device(&sclp_port, driver, 0);
    rc = tty_register_driver(driver);
    if (rc) {
        put_tty_driver(driver);
        return rc;
    }
    sclp_tty_driver = driver;
    return 0;
}
module_init(sclp_tty_init);