con3215.c

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/*
 *  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 ([e-mail]),
 */

#include <linux/config.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/malloc.h>
#include <linux/bootmem.h>
#include <asm/io.h>
#include <asm/ebcdic.h>
#include <asm/uaccess.h>

#include "../../../arch/s390/kernel/cpcmd.h"
#include <asm/irq.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_CCWLEN  3968      /* max. bytes to write with one ccw */
#define RAW3215_NR_CCWS	    ((RAW3215_BUFFER_SIZE/RAW3215_MAX_CCWLEN)+2)
#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 RAW3215_BH_PENDING  256       /* indication for bh scheduling */

struct _raw3215_info;		      /* forward declaration ... */

int raw3215_condevice = -1;           /* preset console device */

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

/*
 * Request structure for a 3215 device
 */
typedef struct _raw3215_req {
	raw3215_type type;	      /* type of the request */
	int start, end;		      /* start/end index into output buffer */
	int residual;		      /* residual count for read request */
	ccw1_t 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 */
} raw3215_req  __attribute__ ((aligned(8)));

typedef struct _raw3215_info {
	int flags;		      /* state flags */
	int irq;		      /* interrupt number to do_IO */
	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 */
	devstat_t devstat;	      /* device status structure for do_IO */
	struct tty_struct *tty;	      /* pointer to tty structure if present */
	struct tq_struct tqueue;      /* task queue to bottom half */
	raw3215_req *queued_read;     /* pointer to queued read requests */
	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 */
	char *message;                /* pending message from raw3215_irq */
	int msg_dstat;                /* dstat for pending message */
	int msg_cstat;                /* cstat for pending message */
} raw3215_info;

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

static struct tty_driver tty3215_driver;
static struct tty_struct *tty3215_table[NR_3215];
static struct termios *tty3215_termios[NR_3215];
static struct termios *tty3215_termios_locked[NR_3215];
static int tty3215_refcount;

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

static int __init con3215_setup(char *str)
{
        int vdev;

        vdev = simple_strtoul(str,&str,16);
        if (vdev >= 0 && vdev < 65536)
                raw3215_condevice = vdev;
        return 1;
}

__setup("condev=", con3215_setup);

/*
 * Get a request structure from the free list
 */
extern inline raw3215_req *raw3215_alloc_req(void) {
	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
 */
extern inline void raw3215_free_req(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);
}

/*
 * Get a write request structure. That is either a new or the last
 * queued write request. The request structure is set up in 
 * raw3215_mk_write_ccw.
 */
static raw3215_req *raw3215_mk_write_req(raw3215_info *raw)
{
	raw3215_req *req;

	/* 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;
		req->start = raw->head;
	} else
		raw->queued_write = NULL;
	return req;
}

/*
 * Get a read request structure. 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 raw3215_req *raw3215_mk_read_req(raw3215_info *raw)
{
	raw3215_req *req;

	/* 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;
	} else
		raw->queued_read = NULL;
	return req;
}

/*
 * Set up a write request with the information from the main structure.
 * A ccw chain is created that writes everything in the output buffer
 * to the 3215 device.
 */
static int raw3215_mk_write_ccw(raw3215_info *raw, raw3215_req *req)
{
	ccw1_t *ccw;
	int len, count, ix;

	ccw = req->ccws;
	req->end = (raw->head - 1) & (RAW3215_BUFFER_SIZE - 1);
	len = ((req->end - req->start) & (RAW3215_BUFFER_SIZE - 1)) + 1;
	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 =
			(void *) virt_to_phys(raw->buffer + ix);
		count = (len > RAW3215_MAX_CCWLEN) ? 
			RAW3215_MAX_CCWLEN : 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++;
	}
	return len;
}

/*
 * Set up a read request that reads up to 160 byte from the 3215 device.
 */
static void raw3215_mk_read_ccw(raw3215_info *raw, raw3215_req *req)
{
	ccw1_t *ccw;

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

/*
 * Start a read or a write request
 */
static void raw3215_start_io(raw3215_info *raw)
{
	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 = do_IO(raw->irq, req->ccws, (__u32) 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 = do_IO(raw->irq, req->ccws, (__u32) 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)
{
	raw3215_info *raw = (raw3215_info *) __data;
	unsigned long flags;

	s390irq_spin_lock_irqsave(raw->irq, flags);
	if (raw->flags & RAW3215_TIMER_RUNS) {
		del_timer(&raw->timer);
		raw->flags &= ~RAW3215_TIMER_RUNS;
		raw3215_start_io(raw);
	}
	s390irq_spin_unlock_irqrestore(raw->irq, flags);
}

/*
 * Function to conditionally start an IO. A read is started immediatly,
 * a write is only started immediatly if the flush flag is on or the
 * amount of data is bigger than RAW3215_MIN_WRITE. If a write is not
 * done immediatly a timer is started with a delay of RAW3215_TIMEOUT.
 */
extern inline void raw3215_try_io(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->count >= RAW3215_MIN_WRITE ||
		    (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;
		}
	}
}

/*
 * The bottom half handler routine for 3215 devices. It tries to start
 * the next IO and wakes up processes waiting on the tty.
 */
static void raw3215_softint(void *data)
{
	raw3215_info *raw;
	struct tty_struct *tty;
	unsigned long flags;

	raw = (raw3215_info *) data;
	s390irq_spin_lock_irqsave(raw->irq, flags);
	raw3215_try_io((raw3215_info *) data);
        raw->flags &= ~RAW3215_BH_PENDING;
	s390irq_spin_unlock_irqrestore(raw->irq, flags);
	/* Check for pending message from raw3215_irq */
	if (raw->message != NULL) {
		printk(raw->message, raw->irq, raw->msg_dstat, raw->msg_cstat);
		raw->message = NULL;
	}
	tty = raw->tty;
	if (tty != NULL &&
	    RAW3215_BUFFER_SIZE - raw->count >= RAW3215_MIN_SPACE) {
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup)(tty);
		wake_up_interruptible(&tty->write_wait);
	}
}

/*
 * Function to safely add raw3215_softint to tq_immediate.
 * The s390irq spinlock must be held.
 */
static inline void raw3215_sched_bh(raw3215_info *raw)
{
        if (raw->flags & RAW3215_BH_PENDING)
                return;       /* already pending */
        raw->flags |= RAW3215_BH_PENDING;
        raw->tqueue.routine = raw3215_softint;
        raw->tqueue.data = raw;
        queue_task(&raw->tqueue, &tq_immediate);
        mark_bh(IMMEDIATE_BH);
}

/*
 * Find the raw3215_info structure associated with irq
 */
static inline raw3215_info *raw3215_find_info(int irq) {
	raw3215_info *raw;
	int i;

	for (i = 0; i < NR_3215; i++) {
		raw = raw3215[i];
		if (raw != NULL && raw->irq == irq &&
		    (raw->flags & RAW3215_ACTIVE))