/*
 *  drivers/s390/char/con3215.c
 *    3215 line mode terminal driver.
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *
 *  Updated:
 *   Aug-2000: Added tab support
 *             Dan Morrison, IBM Corporation (dmorriso@cse.buffalo.edu)
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/vt_kern.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/reboot.h>

#include <linux/slab.h>
#include <linux/bootmem.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/io.h>
#include <asm/ebcdic.h>
#include <asm/uaccess.h>
#include <asm/delay.h>
#include <asm/cpcmd.h>
#include <asm/setup.h>

#include "ctrlchar.h"

#define NR_3215             1
#define NR_3215_REQ         (4*NR_3215)
#define RAW3215_BUFFER_SIZE 65536     /* output buffer size */
#define RAW3215_INBUF_SIZE  256       /* input buffer size */
#define RAW3215_MIN_SPACE   128       /* minimum free space for wakeup */
#define RAW3215_MIN_WRITE   1024      /* min. length for immediate output */
#define RAW3215_MAX_BYTES   3968      /* max. bytes to write with one ssch */
#define RAW3215_MAX_NEWLINE 50        /* max. lines to write with one ssch */
#define RAW3215_NR_CCWS     3
#define RAW3215_TIMEOUT     HZ/10     /* time for delayed output */

#define RAW3215_FIXED       1         /* 3215 console device is not be freed */
#define RAW3215_ACTIVE      2         /* set if the device is in use */
#define RAW3215_WORKING     4         /* set if a request is being worked on */
#define RAW3215_THROTTLED   8         /* set if reading is disabled */
#define RAW3215_STOPPED     16        /* set if writing is disabled */
#define RAW3215_CLOSING     32        /* set while in close process */
#define RAW3215_TIMER_RUNS  64        /* set if the output delay timer is on */
#define RAW3215_FLUSHING    128       /* set to flush buffer (no delay) */

#define TAB_STOP_SIZE       8         /* tab stop size */

/*
 * Request types for a 3215 device
 */
enum raw3215_type {
        RAW3215_FREE, RAW3215_READ, RAW3215_WRITE
};

/*
 * Request structure for a 3215 device
 */
struct raw3215_req {
        enum raw3215_type type;       /* type of the request */
        int start, len;               /* start index & len in output buffer */
        int delayable;                /* indication to wait for more data */
        int residual;                 /* residual count for read request */
        struct ccw1 ccws[RAW3215_NR_CCWS]; /* space for the channel program */
        struct raw3215_info *info;    /* pointer to main structure */
        struct raw3215_req *next;     /* pointer to next request */
} __attribute__ ((aligned(8)));

struct raw3215_info {
        struct ccw_device *cdev;      /* device for tty driver */
        spinlock_t *lock;             /* pointer to irq lock */
        int flags;                    /* state flags */
        char *buffer;                 /* pointer to output buffer */
        char *inbuf;                  /* pointer to input buffer */
        int head;                     /* first free byte in output buffer */
        int count;                    /* number of bytes in output buffer */
        int written;                  /* number of bytes in write requests */
        struct tty_struct *tty;       /* pointer to tty structure if present */
        struct raw3215_req *queued_read; /* pointer to queued read requests */
        struct raw3215_req *queued_write;/* pointer to queued write requests */
        wait_queue_head_t empty_wait; /* wait queue for flushing */
        struct timer_list timer;      /* timer for delayed output */
        int line_pos;                 /* position on the line (for tabs) */
        char ubuffer[80];             /* copy_from_user buffer */
};

/* array of 3215 devices structures */
static struct raw3215_info *raw3215[NR_3215];
/* spinlock to protect the raw3215 array */
static DEFINE_SPINLOCK(raw3215_device_lock);
/* list of free request structures */
static struct raw3215_req *raw3215_freelist;
/* spinlock to protect free list */
static spinlock_t raw3215_freelist_lock;

static struct tty_driver *tty3215_driver;

/*
 * Get a request structure from the free list
 */
static inline struct raw3215_req *
raw3215_alloc_req(void) {
        struct raw3215_req *req;
        unsigned long flags;

        spin_lock_irqsave(&raw3215_freelist_lock, flags);
        req = raw3215_freelist;
        raw3215_freelist = req->next;
        spin_unlock_irqrestore(&raw3215_freelist_lock, flags);
        return req;
}

/*
 * Put a request structure back to the free list
 */
static inline void
raw3215_free_req(struct raw3215_req *req) {
        unsigned long flags;

        if (req->type == RAW3215_FREE)
                return;         /* don't free a free request */
        req->type = RAW3215_FREE;
        spin_lock_irqsave(&raw3215_freelist_lock, flags);
        req->next = raw3215_freelist;
        raw3215_freelist = req;
        spin_unlock_irqrestore(&raw3215_freelist_lock, flags);
}

/*
 * Set up a read request that reads up to 160 byte from the 3215 device.
 * If there is a queued read request it is used, but that shouldn't happen
 * because a 3215 terminal won't accept a new read before the old one is
 * completed.
 */
static void
raw3215_mk_read_req(struct raw3215_info *raw)
{
        struct raw3215_req *req;
        struct ccw1 *ccw;

        /* there can only be ONE read request at a time */
        req = raw->queued_read;
        if (req == NULL) {
                /* no queued read request, use new req structure */
                req = raw3215_alloc_req();
                req->type = RAW3215_READ;
                req->info = raw;
                raw->queued_read = req;
        }

        ccw = req->ccws;
        ccw->cmd_code = 0x0A; /* read inquiry */
        ccw->flags = 0x20;    /* ignore incorrect length */
        ccw->count = 160;
        ccw->cda = (__u32) __pa(raw->inbuf);
}

/*
 * Set up a write request with the information from the main structure.
 * A ccw chain is created that writes as much as possible from the output
 * buffer to the 3215 device. If a queued write exists it is replaced by
 * the new, probably lengthened request.
 */
static void
raw3215_mk_write_req(struct raw3215_info *raw)
{
        struct raw3215_req *req;
        struct ccw1 *ccw;
        int len, count, ix, lines;

        if (raw->count <= raw->written)
                return;
        /* check if there is a queued write request */
        req = raw->queued_write;
        if (req == NULL) {
                /* no queued write request, use new req structure */
                req = raw3215_alloc_req();
                req->type = RAW3215_WRITE;
                req->info = raw;
                raw->queued_write = req;
        } else {
                raw->written -= req->len;
        }

        ccw = req->ccws;
        req->start = (raw->head - raw->count + raw->written) &
                     (RAW3215_BUFFER_SIZE - 1);
        /*
         * now we have to count newlines. We can at max accept
         * RAW3215_MAX_NEWLINE newlines in a single ssch due to
         * a restriction in VM
         */
        lines = 0;
        ix = req->start;
        while (lines < RAW3215_MAX_NEWLINE && ix != raw->head) {
                if (raw->buffer[ix] == 0x15)
                        lines++;
                ix = (ix + 1) & (RAW3215_BUFFER_SIZE - 1);
        }
        len = ((ix - 1 - req->start) & (RAW3215_BUFFER_SIZE - 1)) + 1;
        if (len > RAW3215_MAX_BYTES)
                len = RAW3215_MAX_BYTES;
        req->len = len;
        raw->written += len;

        /* set the indication if we should try to enlarge this request */
        req->delayable = (ix == raw->head) && (len < RAW3215_MIN_WRITE);

        ix = req->start;
        while (len > 0) {
                if (ccw > req->ccws)
                        ccw[-1].flags |= 0x40; /* use command chaining */
                ccw->cmd_code = 0x01; /* write, auto carrier return */
                ccw->flags = 0x20;    /* ignore incorrect length ind.  */
                ccw->cda =
                        (__u32) __pa(raw->buffer + ix);
                count = len;
                if (ix + count > RAW3215_BUFFER_SIZE)
                        count = RAW3215_BUFFER_SIZE - ix;
                ccw->count = count;
                len -= count;
                ix = (ix + count) & (RAW3215_BUFFER_SIZE - 1);
                ccw++;
        }
        /*
         * Add a NOP to the channel program. 3215 devices are purely
         * emulated and its much better to avoid the channel end
         * interrupt in this case.
         */
        if (ccw > req->ccws)
                ccw[-1].flags |= 0x40; /* use command chaining */
        ccw->cmd_code = 0x03; /* NOP */
        ccw->flags = 0;
        ccw->cda = 0;
        ccw->count = 1;
}

/*
 * Start a read or a write request
 */
static void
raw3215_start_io(struct raw3215_info *raw)
{
        struct raw3215_req *req;
        int res;

        req = raw->queued_read;
        if (req != NULL &&
            !(raw->flags & (RAW3215_WORKING | RAW3215_THROTTLED))) {
                /* dequeue request */
                raw->queued_read = NULL;
                res = ccw_device_start(raw->cdev, req->ccws,
                                       (unsigned long) req, 0, 0);
                if (res != 0) {
                        /* do_IO failed, put request back to queue */
                        raw->queued_read = req;
                } else {
                        raw->flags |= RAW3215_WORKING;
                }
        }
        req = raw->queued_write;
        if (req != NULL &&
            !(raw->flags & (RAW3215_WORKING | RAW3215_STOPPED))) {
                /* dequeue request */
                raw->queued_write = NULL;
                res = ccw_device_start(raw->cdev, req->ccws,
                                       (unsigned long) req, 0, 0);
                if (res != 0) {
                        /* do_IO failed, put request back to queue */
                        raw->queued_write = req;
                } else {
                        raw->flags |= RAW3215_WORKING;
                }
        }
}

/*
 * Function to start a delayed output after RAW3215_TIMEOUT seconds
 */
static void
raw3215_timeout(unsigned long __data)
{
        struct raw3215_info *raw = (struct raw3215_info *) __data;
        unsigned long flags;

        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        if (raw->flags & RAW3215_TIMER_RUNS) {
                del_timer(&raw->timer);
                raw->flags &= ~RAW3215_TIMER_RUNS;
                raw3215_mk_write_req(raw);
                raw3215_start_io(raw);
        }
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Function to conditionally start an IO. A read is started immediately,
 * a write is only started immediately if the flush flag is on or the
 * amount of data is bigger than RAW3215_MIN_WRITE. If a write is not
 * done immediately a timer is started with a delay of RAW3215_TIMEOUT.
 */
static inline void
raw3215_try_io(struct raw3215_info *raw)
{
        if (!(raw->flags & RAW3215_ACTIVE))
                return;
        if (raw->queued_read != NULL)
                raw3215_start_io(raw);
        else if (raw->queued_write != NULL) {
                if ((raw->queued_write->delayable == 0) ||
                    (raw->flags & RAW3215_FLUSHING)) {
                        /* execute write requests bigger than minimum size */
                        raw3215_start_io(raw);
                        if (raw->flags & RAW3215_TIMER_RUNS) {
                                del_timer(&raw->timer);
                                raw->flags &= ~RAW3215_TIMER_RUNS;
                        }
                } else if (!(raw->flags & RAW3215_TIMER_RUNS)) {
                        /* delay small writes */
                        init_timer(&raw->timer);
                        raw->timer.expires = RAW3215_TIMEOUT + jiffies;
                        raw->timer.data = (unsigned long) raw;
                        raw->timer.function = raw3215_timeout;
                        add_timer(&raw->timer);
                        raw->flags |= RAW3215_TIMER_RUNS;
                }
        }
}

/*
 * Try to start the next IO and wake up processes waiting on the tty.
 */
static void raw3215_next_io(struct raw3215_info *raw)
{
        struct tty_struct *tty;

        raw3215_mk_write_req(raw);
        raw3215_try_io(raw);
        tty = raw->tty;
        if (tty != NULL &&
            RAW3215_BUFFER_SIZE - raw->count >= RAW3215_MIN_SPACE) {
                tty_wakeup(tty);
        }
}

/*
 * Interrupt routine, called from common io layer
 */
static void
raw3215_irq(struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
{
        struct raw3215_info *raw;
        struct raw3215_req *req;
        struct tty_struct *tty;
        int cstat, dstat;
        int count;

        raw = cdev->dev.driver_data;
        req = (struct raw3215_req *) intparm;
        cstat = irb->scsw.cmd.cstat;
        dstat = irb->scsw.cmd.dstat;
        if (cstat != 0)
                raw3215_next_io(raw);
        if (dstat & 0x01) { /* we got a unit exception */
                dstat &= ~0x01;  /* we can ignore it */
        }
        switch (dstat) {
        case 0x80:
                if (cstat != 0)
                        break;
                /* Attention interrupt, someone hit the enter key */
                raw3215_mk_read_req(raw);
                raw3215_next_io(raw);
                break;
        case 0x08:
        case 0x0C:
                /* Channel end interrupt. */
                if ((raw = req->info) == NULL)
                        return;              /* That shouldn't happen ... */
                if (req->type == RAW3215_READ) {
                        /* store residual count, then wait for device end */
                        req->residual = irb->scsw.cmd.count;
                }
                if (dstat == 0x08)
                        break;
        case 0x04:
                /* Device end interrupt. */
                if ((raw = req->info) == NULL)
                        return;              /* That shouldn't happen ... */
                if (req->type == RAW3215_READ && raw->tty != NULL) {
                        unsigned int cchar;

                        tty = raw->tty;
                        count = 160 - req->residual;
                        EBCASC(raw->inbuf, count);
                        cchar = ctrlchar_handle(raw->inbuf, 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(raw->tty);
                                break;

                        case CTRLCHAR_NONE:
                                if (count < 2 ||
                                    (strncmp(raw->inbuf+count-2, "\252n", 2) &&
                                     strncmp(raw->inbuf+count-2, "^n", 2)) ) {
                                        /* add the auto \n */
                                        raw->inbuf[count] = '\n';
                                        count++;
                                } else
                                        count -= 2;
                                tty_insert_flip_string(tty, raw->inbuf, count);
                                tty_flip_buffer_push(raw->tty);
                                break;
                        }
                } else if (req->type == RAW3215_WRITE) {
                        raw->count -= req->len;
                        raw->written -= req->len;
                }
                raw->flags &= ~RAW3215_WORKING;
                raw3215_free_req(req);
                /* check for empty wait */
                if (waitqueue_active(&raw->empty_wait) &&
                    raw->queued_write == NULL &&
                    raw->queued_read == NULL) {
                        wake_up_interruptible(&raw->empty_wait);
                }
                raw3215_next_io(raw);
                break;
        default:
                /* Strange interrupt, I'll do my best to clean up */
                if (req != NULL && req->type != RAW3215_FREE) {
                        if (req->type == RAW3215_WRITE) {
                                raw->count -= req->len;
                                raw->written -= req->len;
                        }
                        raw->flags &= ~RAW3215_WORKING;
                        raw3215_free_req(req);
                }
                raw3215_next_io(raw);
        }
        return;
}

/*
 * Wait until length bytes are available int the output buffer.
 * Has to be called with the s390irq lock held. Can be called
 * disabled.
 */
static void
raw3215_make_room(struct raw3215_info *raw, unsigned int length)
{
        while (RAW3215_BUFFER_SIZE - raw->count < length) {
                /* there might be a request pending */
                raw->flags |= RAW3215_FLUSHING;
                raw3215_mk_write_req(raw);
                raw3215_try_io(raw);
                raw->flags &= ~RAW3215_FLUSHING;
#ifdef CONFIG_TN3215_CONSOLE
                wait_cons_dev();
#endif
                /* Enough room freed up ? */
                if (RAW3215_BUFFER_SIZE - raw->count >= length)
                        break;
                /* there might be another cpu waiting for the lock */
                spin_unlock(get_ccwdev_lock(raw->cdev));
                udelay(100);
                spin_lock(get_ccwdev_lock(raw->cdev));
        }
}

/*
 * String write routine for 3215 devices
 */
static void
raw3215_write(struct raw3215_info *raw, const char *str, unsigned int length)
{
        unsigned long flags;
        int c, count;

        while (length > 0) {
                spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
                count = (length > RAW3215_BUFFER_SIZE) ?
                                             RAW3215_BUFFER_SIZE : length;
                length -= count;

                raw3215_make_room(raw, count);

                /* copy string to output buffer and convert it to EBCDIC */
                while (1) {
                        c = min_t(int, count,
                                  min(RAW3215_BUFFER_SIZE - raw->count,
                                      RAW3215_BUFFER_SIZE - raw->head));
                        if (c <= 0)
                                break;
                        memcpy(raw->buffer + raw->head, str, c);
                        ASCEBC(raw->buffer + raw->head, c);
                        raw->head = (raw->head + c) & (RAW3215_BUFFER_SIZE - 1);
                        raw->count += c;
                        raw->line_pos += c;
                        str += c;
                        count -= c;
                }
                if (!(raw->flags & RAW3215_WORKING)) {
                        raw3215_mk_write_req(raw);
                        /* start or queue request */
                        raw3215_try_io(raw);
                }
                spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
        }
}

/*
 * Put character routine for 3215 devices
 */
static void
raw3215_putchar(struct raw3215_info *raw, unsigned char ch)
{
        unsigned long flags;
        unsigned int length, i;

        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        if (ch == '\t') {
                length = TAB_STOP_SIZE - (raw->line_pos%TAB_STOP_SIZE);
                raw->line_pos += length;
                ch = ' ';
        } else if (ch == '\n') {
                length = 1;
                raw->line_pos = 0;
        } else {
                length = 1;
                raw->line_pos++;
        }
        raw3215_make_room(raw, length);

        for (i = 0; i < length; i++) {
                raw->buffer[raw->head] = (char) _ascebc[(int) ch];
                raw->head = (raw->head + 1) & (RAW3215_BUFFER_SIZE - 1);
                raw->count++;
        }
        if (!(raw->flags & RAW3215_WORKING)) {
                raw3215_mk_write_req(raw);
                /* start or queue request */
                raw3215_try_io(raw);
        }
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Flush routine, it simply sets the flush flag and tries to start
 * pending IO.
 */
static void
raw3215_flush_buffer(struct raw3215_info *raw)
{
        unsigned long flags;

        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        if (raw->count > 0) {
                raw->flags |= RAW3215_FLUSHING;
                raw3215_try_io(raw);
                raw->flags &= ~RAW3215_FLUSHING;
        }
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Fire up a 3215 device.
 */
static int
raw3215_startup(struct raw3215_info *raw)
{
        unsigned long flags;

        if (raw->flags & RAW3215_ACTIVE)
                return 0;
        raw->line_pos = 0;
        raw->flags |= RAW3215_ACTIVE;
        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        raw3215_try_io(raw);
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);

        return 0;
}

/*
 * Shutdown a 3215 device.
 */
static void
raw3215_shutdown(struct raw3215_info *raw)
{
        DECLARE_WAITQUEUE(wait, current);
        unsigned long flags;

        if (!(raw->flags & RAW3215_ACTIVE) || (raw->flags & RAW3215_FIXED))
                return;
        /* Wait for outstanding requests, then free irq */
        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        if ((raw->flags & RAW3215_WORKING) ||
            raw->queued_write != NULL ||
            raw->queued_read != NULL) {
                raw->flags |= RAW3215_CLOSING;
                add_wait_queue(&raw->empty_wait, &wait);
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
                schedule();
                spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
                remove_wait_queue(&raw->empty_wait, &wait);
                set_current_state(TASK_RUNNING);
                raw->flags &= ~(RAW3215_ACTIVE | RAW3215_CLOSING);
        }
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

static int
raw3215_probe (struct ccw_device *cdev)
{
        struct raw3215_info *raw;
        int line;

        /* Console is special. */
        if (raw3215[0] && (cdev->dev.driver_data == raw3215[0]))
                return 0;
        raw = kmalloc(sizeof(struct raw3215_info) +
                      RAW3215_INBUF_SIZE, GFP_KERNEL|GFP_DMA);
        if (raw == NULL)
                return -ENOMEM;

        spin_lock(&raw3215_device_lock);
        for (line = 0; line < NR_3215; line++) {
                if (!raw3215[line]) {
                        raw3215[line] = raw;
                        break;
                }
        }
        spin_unlock(&raw3215_device_lock);
        if (line == NR_3215) {
                kfree(raw);
                return -ENODEV;
        }

        raw->cdev = cdev;
        raw->inbuf = (char *) raw + sizeof(struct raw3215_info);
        memset(raw, 0, sizeof(struct raw3215_info));
        raw->buffer = kmalloc(RAW3215_BUFFER_SIZE,
                                       GFP_KERNEL|GFP_DMA);
        if (raw->buffer == NULL) {
                spin_lock(&raw3215_device_lock);
                raw3215[line] = NULL;
                spin_unlock(&raw3215_device_lock);
                kfree(raw);
                return -ENOMEM;
        }
        init_waitqueue_head(&raw->empty_wait);

        cdev->dev.driver_data = raw;
        cdev->handler = raw3215_irq;

        return 0;
}

static void
raw3215_remove (struct ccw_device *cdev)
{
        struct raw3215_info *raw;

        ccw_device_set_offline(cdev);
        raw = cdev->dev.driver_data;
        if (raw) {
                cdev->dev.driver_data = NULL;
                kfree(raw->buffer);
                kfree(raw);
        }
}

static int
raw3215_set_online (struct ccw_device *cdev)
{
        struct raw3215_info *raw;

        raw = cdev->dev.driver_data;
        if (!raw)
                return -ENODEV;

        return raw3215_startup(raw);
}

static int
raw3215_set_offline (struct ccw_device *cdev)
{
        struct raw3215_info *raw;

        raw = cdev->dev.driver_data;
        if (!raw)
                return -ENODEV;

        raw3215_shutdown(raw);

        return 0;
}

static struct ccw_device_id raw3215_id[] = {
        { CCW_DEVICE(0x3215, 0) },
        { /* end of list */ },
};

static struct ccw_driver raw3215_ccw_driver = {
        .name           = "3215",
        .owner          = THIS_MODULE,
        .ids            = raw3215_id,
        .probe          = &raw3215_probe,
        .remove         = &raw3215_remove,
        .set_online     = &raw3215_set_online,
        .set_offline    = &raw3215_set_offline,
};

#ifdef CONFIG_TN3215_CONSOLE
/*
 * Write a string to the 3215 console
 */
static void
con3215_write(struct console *co, const char *str, unsigned int count)
{
        struct raw3215_info *raw;
        int i;

        if (count <= 0)
                return;
        raw = raw3215[0];       /* console 3215 is the first one */
        while (count > 0) {
                for (i = 0; i < count; i++)
                        if (str[i] == '\t' || str[i] == '\n')
                                break;
                raw3215_write(raw, str, i);
                count -= i;
                str += i;
                if (count > 0) {
                        raw3215_putchar(raw, *str);
                        count--;
                        str++;
                }
        }
}

static struct tty_driver *con3215_device(struct console *c, int *index)
{
        *index = c->index;
        return tty3215_driver;
}

/*
 * panic() calls con3215_flush through a panic_notifier
 * before the system enters a disabled, endless loop.
 */
static void
con3215_flush(void)
{
        struct raw3215_info *raw;
        unsigned long flags;

        raw = raw3215[0];  /* console 3215 is the first one */
        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        raw3215_make_room(raw, RAW3215_BUFFER_SIZE);
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

static int con3215_notify(struct notifier_block *self,
                          unsigned long event, void *data)
{
        con3215_flush();
        return NOTIFY_OK;
}

static struct notifier_block on_panic_nb = {
        .notifier_call = con3215_notify,
        .priority = 0,
};

static struct notifier_block on_reboot_nb = {
        .notifier_call = con3215_notify,
        .priority = 0,
};

/*
 *  The console structure for the 3215 console
 */
static struct console con3215 = {
        .name    = "ttyS",
        .write   = con3215_write,
        .device  = con3215_device,
        .flags   = CON_PRINTBUFFER,
};

/*
 * 3215 console initialization code called from console_init().
 * NOTE: This is called before kmalloc is available.
 */
static int __init
con3215_init(void)
{
        struct ccw_device *cdev;
        struct raw3215_info *raw;
        struct raw3215_req *req;
        int i;

        /* Check if 3215 is to be the console */
        if (!CONSOLE_IS_3215)
                return -ENODEV;

        /* Set the console mode for VM */
        if (MACHINE_IS_VM) {
                cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
                cpcmd("TERM AUTOCR OFF", NULL, 0, NULL);
        }

        /* allocate 3215 request structures */
        raw3215_freelist = NULL;
        spin_lock_init(&raw3215_freelist_lock);
        for (i = 0; i < NR_3215_REQ; i++) {
                req = (struct raw3215_req *) alloc_bootmem_low(sizeof(struct raw3215_req));
                req->next = raw3215_freelist;
                raw3215_freelist = req;
        }

        cdev = ccw_device_probe_console();
        if (IS_ERR(cdev))
                return -ENODEV;

        raw3215[0] = raw = (struct raw3215_info *)
                alloc_bootmem_low(sizeof(struct raw3215_info));
        memset(raw, 0, sizeof(struct raw3215_info));
        raw->buffer = (char *) alloc_bootmem_low(RAW3215_BUFFER_SIZE);
        raw->inbuf = (char *) alloc_bootmem_low(RAW3215_INBUF_SIZE);
        raw->cdev = cdev;
        cdev->dev.driver_data = raw;
        cdev->handler = raw3215_irq;

        raw->flags |= RAW3215_FIXED;
        init_waitqueue_head(&raw->empty_wait);

        /* Request the console irq */
        if (raw3215_startup(raw) != 0) {
                free_bootmem((unsigned long) raw->inbuf, RAW3215_INBUF_SIZE);
                free_bootmem((unsigned long) raw->buffer, RAW3215_BUFFER_SIZE);
                free_bootmem((unsigned long) raw, sizeof(struct raw3215_info));
                raw3215[0] = NULL;
                return -ENODEV;
        }
        atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
        register_reboot_notifier(&on_reboot_nb);
        register_console(&con3215);
        return 0;
}
console_initcall(con3215_init);
#endif

/*
 * tty3215_open
 *
 * This routine is called whenever a 3215 tty is opened.
 */
static int
tty3215_open(struct tty_struct *tty, struct file * filp)
{
        struct raw3215_info *raw;
        int retval, line;

        line = tty->index;
        if ((line < 0) || (line >= NR_3215))
                return -ENODEV;

        raw = raw3215[line];
        if (raw == NULL)
                return -ENODEV;

        tty->driver_data = raw;
        raw->tty = tty;

        tty->low_latency = 0;  /* don't use bottom half for pushing chars */
        /*
         * Start up 3215 device
         */
        retval = raw3215_startup(raw);
        if (retval)
                return retval;

        return 0;
}

/*
 * tty3215_close()
 *
 * This routine is called when the 3215 tty is closed. We wait
 * for the remaining request to be completed. Then we clean up.
 */
static void
tty3215_close(struct tty_struct *tty, struct file * filp)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;
        if (raw == NULL || tty->count > 1)
                return;
        tty->closing = 1;
        /* Shutdown the terminal */
        raw3215_shutdown(raw);
        tty->closing = 0;
        raw->tty = NULL;
}

/*
 * Returns the amount of free space in the output buffer.
 */
static int
tty3215_write_room(struct tty_struct *tty)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;

        /* Subtract TAB_STOP_SIZE to allow for a tab, 8 <<< 64K */
        if ((RAW3215_BUFFER_SIZE - raw->count - TAB_STOP_SIZE) >= 0)
                return RAW3215_BUFFER_SIZE - raw->count - TAB_STOP_SIZE;
        else
                return 0;
}

/*
 * String write routine for 3215 ttys
 */
static int
tty3215_write(struct tty_struct * tty,
              const unsigned char *buf, int count)
{
        struct raw3215_info *raw;

        if (!tty)
                return 0;
        raw = (struct raw3215_info *) tty->driver_data;
        raw3215_write(raw, buf, count);
        return count;
}

/*
 * Put character routine for 3215 ttys
 */
static int
tty3215_put_char(struct tty_struct *tty, unsigned char ch)
{
        struct raw3215_info *raw;

        if (!tty)
                return 0;
        raw = (struct raw3215_info *) tty->driver_data;
        raw3215_putchar(raw, ch);
        return 1;
}

static void
tty3215_flush_chars(struct tty_struct *tty)
{
}

/*
 * Returns the number of characters in the output buffer
 */
static int
tty3215_chars_in_buffer(struct tty_struct *tty)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;
        return raw->count;
}

static void
tty3215_flush_buffer(struct tty_struct *tty)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;
        raw3215_flush_buffer(raw);
        tty_wakeup(tty);
}

/*
 * Currently we don't have any io controls for 3215 ttys
 */
static int
tty3215_ioctl(struct tty_struct *tty, struct file * file,
              unsigned int cmd, unsigned long arg)
{
        if (tty->flags & (1 << TTY_IO_ERROR))
                return -EIO;

        switch (cmd) {
        default:
                return -ENOIOCTLCMD;
        }
        return 0;
}

/*
 * Disable reading from a 3215 tty
 */
static void
tty3215_throttle(struct tty_struct * tty)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;
        raw->flags |= RAW3215_THROTTLED;
}

/*
 * Enable reading from a 3215 tty
 */
static void
tty3215_unthrottle(struct tty_struct * tty)
{
        struct raw3215_info *raw;
        unsigned long flags;

        raw = (struct raw3215_info *) tty->driver_data;
        if (raw->flags & RAW3215_THROTTLED) {
                spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
                raw->flags &= ~RAW3215_THROTTLED;
                raw3215_try_io(raw);
                spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
        }
}

/*
 * Disable writing to a 3215 tty
 */
static void
tty3215_stop(struct tty_struct *tty)
{
        struct raw3215_info *raw;

        raw = (struct raw3215_info *) tty->driver_data;
        raw->flags |= RAW3215_STOPPED;
}

/*
 * Enable writing to a 3215 tty
 */
static void
tty3215_start(struct tty_struct *tty)
{
        struct raw3215_info *raw;
        unsigned long flags;

        raw = (struct raw3215_info *) tty->driver_data;
        if (raw->flags & RAW3215_STOPPED) {
                spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
                raw->flags &= ~RAW3215_STOPPED;
                raw3215_try_io(raw);
                spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
        }
}

static const struct tty_operations tty3215_ops = {
        .open = tty3215_open,
        .close = tty3215_close,
        .write = tty3215_write,
        .put_char = tty3215_put_char,
        .flush_chars = tty3215_flush_chars,
        .write_room = tty3215_write_room,
        .chars_in_buffer = tty3215_chars_in_buffer,
        .flush_buffer = tty3215_flush_buffer,
        .ioctl = tty3215_ioctl,
        .throttle = tty3215_throttle,
        .unthrottle = tty3215_unthrottle,
        .stop = tty3215_stop,
        .start = tty3215_start,
};

/*
 * 3215 tty registration code called from tty_init().
 * Most kernel services (incl. kmalloc) are available at this poimt.
 */
static int __init
tty3215_init(void)
{
        struct tty_driver *driver;
        int ret;

        if (!CONSOLE_IS_3215)
                return 0;

        driver = alloc_tty_driver(NR_3215);
        if (!driver)
                return -ENOMEM;

        ret = ccw_driver_register(&raw3215_ccw_driver);
        if (ret) {
                put_tty_driver(driver);
                return ret;
        }
        /*
         * Initialize the tty_driver structure
         * Entries in tty3215_driver that are NOT initialized:
         * proc_entry, set_termios, flush_buffer, set_ldisc, write_proc
         */

        driver->owner = THIS_MODULE;
        driver->driver_name = "tty3215";
        driver->name = "ttyS";
        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;
        driver->flags = TTY_DRIVER_REAL_RAW;
        tty_set_operations(driver, &tty3215_ops);
        ret = tty_register_driver(driver);
        if (ret) {
                put_tty_driver(driver);
                return ret;
        }
        tty3215_driver = driver;
        return 0;
}

static void __exit
tty3215_exit(void)
{
        tty_unregister_driver(tty3215_driver);
        put_tty_driver(tty3215_driver);
        ccw_driver_unregister(&raw3215_ccw_driver);
}

module_init(tty3215_init);
module_exit(tty3215_exit);