drm/rockchip: Don't change hdmi reference clock rate

[drm/drm-misc.git] / drivers / s390 / char / con3215.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 3215 line mode terminal driver.
 *
 * Copyright IBM Corp. 1999, 2009
 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 *
 * Updated:
 *  Aug-2000: Added tab support
 *            Dan Morrison, IBM Corporation <dmorriso@cse.buffalo.edu>
 */

#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/panic_notifier.h>
#include <linux/reboot.h>
#include <linux/serial.h> /* ASYNC_* flags */
#include <linux/slab.h>
#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <linux/io.h>
#include <asm/ebcdic.h>
#include <linux/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_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_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 tty_port port;
        struct ccw_device *cdev;      /* device for tty driver */
        spinlock_t *lock;             /* pointer to irq lock */
        int flags;                    /* state flags */
        u8 *buffer;                   /* pointer to output buffer */
        u8 *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 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) */
};

/* 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 DEFINE_SPINLOCK(raw3215_freelist_lock);

static struct tty_driver *tty3215_driver;
static bool con3215_drop = true;

/*
 * 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 = virt_to_dma32(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 = virt_to_dma32(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(struct timer_list *t)
{
        struct raw3215_info *raw = from_timer(raw, t, timer);
        unsigned long flags;

        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
        raw->flags &= ~RAW3215_TIMER_RUNS;
        raw3215_mk_write_req(raw);
        raw3215_start_io(raw);
        if ((raw->queued_read || raw->queued_write) &&
            !(raw->flags & RAW3215_WORKING) &&
            !(raw->flags & RAW3215_TIMER_RUNS)) {
                raw->timer.expires = RAW3215_TIMEOUT + jiffies;
                add_timer(&raw->timer);
                raw->flags |= RAW3215_TIMER_RUNS;
        }
        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 (!tty_port_initialized(&raw->port))
                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->queued_read || raw->queued_write) &&
            !(raw->flags & RAW3215_WORKING) &&
            !(raw->flags & RAW3215_TIMER_RUNS)) {
                raw->timer.expires = RAW3215_TIMEOUT + jiffies;
                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);
        if (tty && 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 = dev_get_drvdata(&cdev->dev);
        req = (struct raw3215_req *) intparm;
        tty = tty_port_tty_get(&raw->port);
        cstat = irb->scsw.cmd.cstat;
        dstat = irb->scsw.cmd.dstat;
        if (cstat != 0)
                raw3215_next_io(raw, tty);
        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, tty);
                break;
        case 0x08:
        case 0x0C:
                /* Channel end interrupt. */
                if ((raw = req->info) == NULL)
                        goto put_tty;        /* 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;
                fallthrough;
        case 0x04:
                /* Device end interrupt. */
                if ((raw = req->info) == NULL)
                        goto put_tty;        /* That shouldn't happen ... */
                if (req->type == RAW3215_READ && tty != NULL) {
                        unsigned int cchar;

                        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(&raw->port, cchar,
                                                TTY_NORMAL);
                                tty_flip_buffer_push(&raw->port);
                                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(&raw->port, raw->inbuf,
                                                count);
                                tty_flip_buffer_push(&raw->port);
                                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, tty);
                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, tty);
        }
put_tty:
        tty_kref_put(tty);
}

/*
 * Need to drop data to avoid blocking. Drop as much data as possible.
 * This is unqueued part in the buffer and the queued part in the request.
 * Also adjust the head position to append new data and set count
 * accordingly.
 *
 * Return number of bytes available in buffer.
 */
static unsigned int raw3215_drop(struct raw3215_info *raw)
{
        struct raw3215_req *req;

        req = raw->queued_write;
        if (req) {
                /* Drop queued data and delete request */
                raw->written -= req->len;
                raw3215_free_req(req);
                raw->queued_write = NULL;
        }
        raw->head = (raw->head - raw->count + raw->written) &
                    (RAW3215_BUFFER_SIZE - 1);
        raw->count = raw->written;

        return RAW3215_BUFFER_SIZE - raw->count;
}

/*
 * Wait until length bytes are available int the output buffer.
 * If drop mode is active and wait condition holds true, start dropping
 * data.
 * Has to be called with the s390irq lock held. Can be called
 * disabled.
 */
static unsigned int raw3215_make_room(struct raw3215_info *raw,
                                      unsigned int length, bool drop)
{
        while (RAW3215_BUFFER_SIZE - raw->count < length) {
                if (drop)
                        return raw3215_drop(raw);

                /* 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
                ccw_device_wait_idle(raw->cdev);
#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));
        }
        return length;
}

#define RAW3215_COUNT   1
#define RAW3215_STORE   2

/*
 * Add text to console buffer. Find tabs in input and calculate size
 * including tab replacement.
 * This function operates in 2 different modes, depending on parameter
 * opmode:
 * RAW3215_COUNT: Get the size needed for the input string with
 *      proper tab replacement calculation.
 *      Return value is the number of bytes required to store the
 *      input. However no data is actually stored.
 *      The parameter todrop is not used.
 * RAW3215_STORE: Add data to the console buffer. The parameter todrop is
 *      valid and contains the number of bytes to be dropped from head of
 *      string  without blocking.
 *      Return value is the number of bytes copied.
 */
static unsigned int raw3215_addtext(const u8 *str, size_t length,
                                    struct raw3215_info *raw, int opmode,
                                    unsigned int todrop)
{
        unsigned int i, blanks, expanded_size = 0;
        unsigned int column = raw->line_pos;
        size_t c;
        u8 ch;

        if (opmode == RAW3215_COUNT)
                todrop = 0;

        for (c = 0; c < length; ++c) {
                blanks = 1;
                ch = str[c];

                switch (ch) {
                case '\n':
                        expanded_size++;
                        column = 0;
                        break;
                case '\t':
                        blanks = TAB_STOP_SIZE - (column % TAB_STOP_SIZE);
                        column += blanks;
                        expanded_size += blanks;
                        ch = ' ';
                        break;
                default:
                        expanded_size++;
                        column++;
                        break;
                }

                if (opmode == RAW3215_COUNT)
                        continue;
                if (todrop && expanded_size < todrop)   /* Drop head data */
                        continue;
                for (i = 0; i < blanks; i++) {
                        raw->buffer[raw->head] = _ascebc[ch];
                        raw->head = (raw->head + 1) & (RAW3215_BUFFER_SIZE - 1);
                        raw->count++;
                }
                raw->line_pos = column;
        }
        return expanded_size - todrop;
}

/*
 * String write routine for 3215 devices
 */
static void raw3215_write(struct raw3215_info *raw, const u8 *str,
                          size_t length)
{
        unsigned int count, avail;
        unsigned long flags;

        spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);

        count = raw3215_addtext(str, length, raw, RAW3215_COUNT, 0);

        avail = raw3215_make_room(raw, count, con3215_drop);
        if (avail) {
                raw3215_addtext(str, length, raw, RAW3215_STORE,
                                count - avail);
        }
        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, u8 ch)
{
        raw3215_write(raw, &ch, 1);
}

/*
 * 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 (tty_port_initialized(&raw->port))
                return 0;
        raw->line_pos = 0;
        tty_port_set_initialized(&raw->port, true);
        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 (!tty_port_initialized(&raw->port) || (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) {
                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);
                tty_port_set_initialized(&raw->port, true);
        }
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

static struct raw3215_info *raw3215_alloc_info(void)
{
        struct raw3215_info *info;

        info = kzalloc(sizeof(struct raw3215_info), GFP_KERNEL | GFP_DMA);
        if (!info)
                return NULL;

        info->buffer = kzalloc(RAW3215_BUFFER_SIZE, GFP_KERNEL | GFP_DMA);
        info->inbuf = kzalloc(RAW3215_INBUF_SIZE, GFP_KERNEL | GFP_DMA);
        if (!info->buffer || !info->inbuf) {
                kfree(info->inbuf);
                kfree(info->buffer);
                kfree(info);
                return NULL;
        }

        timer_setup(&info->timer, raw3215_timeout, 0);
        init_waitqueue_head(&info->empty_wait);
        tty_port_init(&info->port);

        return info;
}

static void raw3215_free_info(struct raw3215_info *raw)
{
        kfree(raw->inbuf);
        kfree(raw->buffer);
        tty_port_destroy(&raw->port);
        kfree(raw);
}

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

        /* Console is special. */
        if (raw3215[0] && (raw3215[0] == dev_get_drvdata(&cdev->dev)))
                return 0;

        raw = raw3215_alloc_info();
        if (raw == NULL)
                return -ENOMEM;

        raw->cdev = cdev;
        dev_set_drvdata(&cdev->dev, raw);
        cdev->handler = raw3215_irq;

        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) {
                raw3215_free_info(raw);
                return -ENODEV;
        }

        return 0;
}

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

        ccw_device_set_offline(cdev);
        raw = dev_get_drvdata(&cdev->dev);
        if (raw) {
                spin_lock(&raw3215_device_lock);
                for (line = 0; line < NR_3215; line++)
                        if (raw3215[line] == raw)
                                break;
                raw3215[line] = NULL;
                spin_unlock(&raw3215_device_lock);
                dev_set_drvdata(&cdev->dev, NULL);
                raw3215_free_info(raw);
        }
}

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

        raw = dev_get_drvdata(&cdev->dev);
        if (!raw)
                return -ENODEV;

        return raw3215_startup(raw);
}

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

        raw = dev_get_drvdata(&cdev->dev);
        if (!raw)
                return -ENODEV;

        raw3215_shutdown(raw);

        return 0;
}

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

static ssize_t con_drop_store(struct device_driver *dev, const char *buf, size_t count)
{
        bool drop;
        int rc;

        rc = kstrtobool(buf, &drop);
        if (!rc)
                con3215_drop = drop;
        return rc ?: count;
}

static ssize_t con_drop_show(struct device_driver *dev, char *buf)
{
        return sysfs_emit(buf, "%d\n", con3215_drop ? 1 : 0);
}

static DRIVER_ATTR_RW(con_drop);

static struct attribute *con3215_drv_attrs[] = {
        &driver_attr_con_drop.attr,
        NULL,
};

static struct attribute_group con3215_drv_attr_group = {
        .attrs = con3215_drv_attrs,
};

static const struct attribute_group *con3215_drv_attr_groups[] = {
        &con3215_drv_attr_group,
        NULL,
};

static struct ccw_driver raw3215_ccw_driver = {
        .driver = {
                .name   = "3215",
                .groups = con3215_drv_attr_groups,
                .owner  = THIS_MODULE,
        },
        .ids            = raw3215_id,
        .probe          = &raw3215_probe,
        .remove         = &raw3215_remove,
        .set_online     = &raw3215_set_online,
        .set_offline    = &raw3215_set_offline,
        .int_class      = IRQIO_C15,
};

static void handle_write(struct raw3215_info *raw, const u8 *str, size_t count)
{
        while (count > 0) {
                size_t i = min_t(size_t, count, RAW3215_BUFFER_SIZE - 1);
                raw3215_write(raw, str, i);
                count -= i;
                str += i;
        }
}

#ifdef CONFIG_TN3215_CONSOLE
/*
 * Write a string to the 3215 console
 */
static void con3215_write(struct console *co, const char *str, unsigned int count)
{
        handle_write(raw3215[0], str, count);
}

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

/*
 * The below function is called as a panic/reboot notifier before the
 * system enters a disabled, endless loop.
 *
 * Notice we must use the spin_trylock() alternative, to prevent lockups
 * in atomic context (panic routine runs with secondary CPUs, local IRQs
 * and preemption disabled).
 */
static int con3215_notify(struct notifier_block *self,
                          unsigned long event, void *data)
{
        struct raw3215_info *raw;
        unsigned long flags;

        raw = raw3215[0];  /* console 3215 is the first one */
        if (!spin_trylock_irqsave(get_ccwdev_lock(raw->cdev), flags))
                return NOTIFY_DONE;
        raw3215_make_room(raw, RAW3215_BUFFER_SIZE, false);
        spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);

        return NOTIFY_DONE;
}

static struct notifier_block on_panic_nb = {
        .notifier_call = con3215_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

static struct notifier_block on_reboot_nb = {
        .notifier_call = con3215_notify,
        .priority = INT_MIN + 1, /* run the callback late */
};

/*
 *  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().
 */
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;
        for (i = 0; i < NR_3215_REQ; i++) {
                req = kzalloc(sizeof(struct raw3215_req), GFP_KERNEL | GFP_DMA);
                if (!req)
                        return -ENOMEM;
                req->next = raw3215_freelist;
                raw3215_freelist = req;
        }

        cdev = ccw_device_create_console(&raw3215_ccw_driver);
        if (IS_ERR(cdev))
                return -ENODEV;

        raw3215[0] = raw = raw3215_alloc_info();
        raw->cdev = cdev;
        dev_set_drvdata(&cdev->dev, raw);
        cdev->handler = raw3215_irq;

        raw->flags |= RAW3215_FIXED;
        if (ccw_device_enable_console(cdev)) {
                ccw_device_destroy_console(cdev);
                raw3215_free_info(raw);
                raw3215[0] = NULL;
                return -ENODEV;
        }

        /* Request the console irq */
        if (raw3215_startup(raw) != 0) {
                raw3215_free_info(raw);
                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

static int tty3215_install(struct tty_driver *driver, struct tty_struct *tty)
{
        struct raw3215_info *raw;

        raw = raw3215[tty->index];
        if (raw == NULL)
                return -ENODEV;

        tty->driver_data = raw;

        return tty_port_install(&raw->port, driver, tty);
}

/*
 * 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 = tty->driver_data;

        tty_port_tty_set(&raw->port, tty);

        /*
         * Start up 3215 device
         */
        return raw3215_startup(raw);
}

/*
 * 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 = tty->driver_data;

        if (raw == NULL || tty->count > 1)
                return;
        tty->closing = 1;
        /* Shutdown the terminal */
        raw3215_shutdown(raw);
        tty->closing = 0;
        tty_port_tty_set(&raw->port, NULL);
}

/*
 * Returns the amount of free space in the output buffer.
 */
static unsigned int tty3215_write_room(struct tty_struct *tty)
{
        struct raw3215_info *raw = 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 ssize_t tty3215_write(struct tty_struct *tty, const u8 *buf,
                             size_t count)
{
        handle_write(tty->driver_data, buf, count);
        return count;
}

/*
 * Put character routine for 3215 ttys
 */
static int tty3215_put_char(struct tty_struct *tty, u8 ch)
{
        struct raw3215_info *raw = 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 unsigned int tty3215_chars_in_buffer(struct tty_struct *tty)
{
        struct raw3215_info *raw = tty->driver_data;

        return raw->count;
}

static void tty3215_flush_buffer(struct tty_struct *tty)
{
        struct raw3215_info *raw = tty->driver_data;

        raw3215_flush_buffer(raw);
        tty_wakeup(tty);
}

/*
 * Disable reading from a 3215 tty
 */
static void tty3215_throttle(struct tty_struct *tty)
{
        struct raw3215_info *raw = 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 = tty->driver_data;
        unsigned long flags;

        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 = 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 = tty->driver_data;
        unsigned long flags;

        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 = {
        .install = tty3215_install,
        .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,
        .throttle = tty3215_throttle,
        .unthrottle = tty3215_unthrottle,
        .stop = tty3215_stop,
        .start = tty3215_start,
};

static int __init con3215_setup_drop(char *str)
{
        bool drop;
        int rc;

        rc = kstrtobool(str, &drop);
        if (!rc)
                con3215_drop = drop;
        return rc;
}
early_param("con3215_drop", con3215_setup_drop);

/*
 * 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 = tty_alloc_driver(NR_3215, TTY_DRIVER_REAL_RAW);
        if (IS_ERR(driver))
                return PTR_ERR(driver);

        ret = ccw_driver_register(&raw3215_ccw_driver);
        if (ret) {
                tty_driver_kref_put(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->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;
        driver->init_termios.c_lflag = ISIG;
        tty_set_operations(driver, &tty3215_ops);
        ret = tty_register_driver(driver);
        if (ret) {
                tty_driver_kref_put(driver);
                return ret;
        }
        tty3215_driver = driver;
        return 0;
}
device_initcall(tty3215_init);