sclp_tty.c

linux-2.6.15.6

/*
 *  drivers/s390/char/sclp_tty.c
 *    SCLP line mode terminal driver.
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Peschke <[e-mail]>
 *		 Martin Schwidefsky <[e-mail]>
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>

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

#define SCLP_TTY_PRINT_HEADER "sclp tty driver: "

/*
 * 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;
/* Waitqueue to wait for buffers to get empty. */
static wait_queue_head_t sclp_tty_waitq;

static struct tty_struct *sclp_tty;
static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
static unsigned short int sclp_tty_chars_count;

struct tty_driver *sclp_tty_driver;

extern struct termios  tty_std_termios;

static struct sclp_ioctls sclp_ioctls;
static struct sclp_ioctls sclp_ioctls_init =
{
	8,			/* 1 hor. tab. = 8 spaces */
	0,			/* no echo of input by this driver */
	80,			/* 80 characters/line */
	1,			/* write after 1/10 s without final new line */
	MAX_KMEM_PAGES,		/* quick fix: avoid __alloc_pages */
	MAX_KMEM_PAGES,		/* take 32/64 pages from kernel memory, */
	0,			/* do not convert to lower case */
	0x6c			/* to seprate 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)
{
	sclp_tty = 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;
	sclp_tty = NULL;
}

/* execute commands to control the i/o behaviour of the SCLP tty at runtime */
static int
sclp_tty_ioctl(struct tty_struct *tty, struct file * file,
	       unsigned int cmd, unsigned long arg)
{
	unsigned long flags;
	unsigned int obuf;
	int check;
	int rc;

	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;
	rc = 0;
	check = 0;
	switch (cmd) {
	case TIOCSCLPSHTAB:
		/* set width of horizontal tab	*/
		if (get_user(sclp_ioctls.htab, (unsigned short __user *) arg))
			rc = -EFAULT;
		else
			check = 1;
		break;
	case TIOCSCLPGHTAB:
		/* get width of horizontal tab	*/
		if (put_user(sclp_ioctls.htab, (unsigned short __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSECHO:
		/* enable/disable echo of input */
		if (get_user(sclp_ioctls.echo, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPGECHO:
		/* Is echo of input enabled ?  */
		if (put_user(sclp_ioctls.echo, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSCOLS:
		/* set number of columns for output  */
		if (get_user(sclp_ioctls.columns, (unsigned short __user *) arg))
			rc = -EFAULT;
		else
			check = 1;
		break;
	case TIOCSCLPGCOLS:
		/* get number of columns for output  */
		if (put_user(sclp_ioctls.columns, (unsigned short __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSNL:
		/* enable/disable writing without final new line character  */
		if (get_user(sclp_ioctls.final_nl, (signed char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPGNL:
		/* Is writing without final new line character enabled ?  */
		if (put_user(sclp_ioctls.final_nl, (signed char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSOBUF:
		/*
		 * set the maximum buffers size for output, will be rounded
		 * up to next 4kB boundary and stored as number of SCCBs
		 * (4kB Buffers) limitation: 256 x 4kB
		 */
		if (get_user(obuf, (unsigned int __user *) arg) == 0) {
			if (obuf & 0xFFF)
				sclp_ioctls.max_sccb = (obuf >> 12) + 1;
			else
				sclp_ioctls.max_sccb = (obuf >> 12);
		} else
			rc = -EFAULT;
		break;
	case TIOCSCLPGOBUF:
		/* get the maximum buffers size for output  */
		obuf = sclp_ioctls.max_sccb << 12;
		if (put_user(obuf, (unsigned int __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPGKBUF:
		/* get the number of buffers got from kernel at startup */
		if (put_user(sclp_ioctls.kmem_sccb, (unsigned short __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSCASE:
		/* enable/disable conversion from upper to lower case */
		if (get_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPGCASE:
		/* Is conversion from upper to lower case of input enabled? */
		if (put_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSDELIM:
		/*
		 * set special character used for separating upper and
		 * lower case, 0x00 disables this feature
		 */
		if (get_user(sclp_ioctls.delim, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPGDELIM:
		/*
		 * get special character used for separating upper and
		 * lower case, 0x00 disables this feature
		 */
		if (put_user(sclp_ioctls.delim, (unsigned char __user *) arg))
			rc = -EFAULT;
		break;
	case TIOCSCLPSINIT:
		/* set initial (default) sclp ioctls  */
		sclp_ioctls = sclp_ioctls_init;
		check = 1;
		break;
	default:
		rc = -ENOIOCTLCMD;
		break;
	}
	if (check) {
		spin_lock_irqsave(&sclp_tty_lock, flags);
		if (sclp_ttybuf != NULL) {
			sclp_set_htab(sclp_ttybuf, sclp_ioctls.htab);
			sclp_set_columns(sclp_ttybuf, sclp_ioctls.columns);
		}
		spin_unlock_irqrestore(&sclp_tty_lock, flags);
	}
	return rc;
}

/*
 * 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)
{
	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));
	wake_up(&sclp_tty_waitq);
	/* check if the tty needs a wake up call */
	if (sclp_tty != NULL) {
		tty_wakeup(sclp_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 void
sclp_tty_write_string(const unsigned char *str, int count)
{
	unsigned long flags;
	void *page;
	int written;
	struct sclp_buffer *buf;

	if (count <= 0)
		return;
	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 (in_interrupt())
					sclp_sync_wait();
				else
					wait_event(sclp_tty_waitq,
						!list_empty(&sclp_tty_pages));
				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_ioctls.columns,
						       sclp_ioctls.htab);
		}
		/* try to write the string to the current output buffer */
		written = sclp_write(sclp_ttybuf, str, count);
		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_ioctls.final_nl) {
		if (sclp_ttybuf != NULL &&
		    sclp_chars_in_buffer(sclp_ttybuf) != 0 &&
		    !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);
		}
	} else {
		if (sclp_ttybuf != NULL &&
		    sclp_chars_in_buffer(sclp_ttybuf) != 0) {
			buf = sclp_ttybuf;
			sclp_ttybuf = NULL;
			spin_unlock_irqrestore(&sclp_tty_lock, flags);
			__sclp_ttybuf_emit(buf);
			spin_lock_irqsave(&sclp_tty_lock, flags);
		}
	}
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
}

/*
 * 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);
		sclp_tty_chars_count = 0;
	}
	sclp_tty_write_string(buf, count);
	return count;
}