/*
   * IBM/3270 Driver - fullscreen driver.
   *
   * Author(s):
   *   Original 3270 Code for 2.4 written by Richard Hitt (UTS Global)
   *   Rewritten for 2.5/2.6 by Martin Schwidefsky <schwidefsky@de.ibm.com>
   *     Copyright IBM Corp. 2003, 2009
   */
  
  #include <linux/bootmem.h>
  #include <linux/console.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/compat.h>
  #include <linux/module.h>
  #include <linux/list.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  
  #include <asm/compat.h>
  #include <asm/ccwdev.h>
  #include <asm/cio.h>
  #include <asm/ebcdic.h>
  #include <asm/idals.h>
  
  #include "raw3270.h"
  #include "ctrlchar.h"
  
  static struct raw3270_fn fs3270_fn;
  
  struct fs3270 {
  	struct raw3270_view view;
  	struct pid *fs_pid;		/* Pid of controlling program. */
  	int read_command;		/* ccw command to use for reads. */
  	int write_command;		/* ccw command to use for writes. */
  	int attention;			/* Got attention. */
  	int active;			/* Fullscreen view is active. */
  	struct raw3270_request *init;	/* single init request. */
  	wait_queue_head_t wait;		/* Init & attention wait queue. */
  	struct idal_buffer *rdbuf;	/* full-screen-deactivate buffer */
  	size_t rdbuf_size;		/* size of data returned by RDBUF */
  };
  
  static DEFINE_MUTEX(fs3270_mutex);
  
  static void
  fs3270_wake_up(struct raw3270_request *rq, void *data)
  {
  	wake_up((wait_queue_head_t *) data);
  }
  
  static inline int
  fs3270_working(struct fs3270 *fp)
  {
  	/*
  	 * The fullscreen view is in working order if the view
  	 * has been activated AND the initial request is finished.
  	 */
  	return fp->active && raw3270_request_final(fp->init);
  }
  
  static int
  fs3270_do_io(struct raw3270_view *view, struct raw3270_request *rq)
  {
  	struct fs3270 *fp;
  	int rc;
  
  	fp = (struct fs3270 *) view;
  	rq->callback = fs3270_wake_up;
  	rq->callback_data = &fp->wait;
  
  	do {
  		if (!fs3270_working(fp)) {
  			/* Fullscreen view isn't ready yet. */
  			rc = wait_event_interruptible(fp->wait,
  						      fs3270_working(fp));
  			if (rc != 0)
  				break;
  		}
  		rc = raw3270_start(view, rq);
  		if (rc == 0) {
  			/* Started successfully. Now wait for completion. */
  			wait_event(fp->wait, raw3270_request_final(rq));
  		}
  	} while (rc == -EACCES);
  	return rc;
  }
  
  /*
   * Switch to the fullscreen view.
   */
  static void
  fs3270_reset_callback(struct raw3270_request *rq, void *data)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) rq->view;
  	raw3270_request_reset(rq);
  	wake_up(&fp->wait);
  }
  
  static void
  fs3270_restore_callback(struct raw3270_request *rq, void *data)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) rq->view;
  	if (rq->rc != 0 || rq->rescnt != 0) {
  		if (fp->fs_pid)
  			kill_pid(fp->fs_pid, SIGHUP, 1);
  	}
  	fp->rdbuf_size = 0;
  	raw3270_request_reset(rq);
  	wake_up(&fp->wait);
  }
  
  static int
  fs3270_activate(struct raw3270_view *view)
  {
  	struct fs3270 *fp;
  	char *cp;
  	int rc;
  
  	fp = (struct fs3270 *) view;
  
  	/* If an old init command is still running just return. */
  	if (!raw3270_request_final(fp->init))
  		return 0;
  
  	if (fp->rdbuf_size == 0) {
  		/* No saved buffer. Just clear the screen. */
  		raw3270_request_set_cmd(fp->init, TC_EWRITEA);
  		fp->init->callback = fs3270_reset_callback;
  	} else {
  		/* Restore fullscreen buffer saved by fs3270_deactivate. */
  		raw3270_request_set_cmd(fp->init, TC_EWRITEA);
  		raw3270_request_set_idal(fp->init, fp->rdbuf);
  		fp->init->ccw.count = fp->rdbuf_size;
  		cp = fp->rdbuf->data[0];
  		cp[0] = TW_KR;
  		cp[1] = TO_SBA;
  		cp[2] = cp[6];
  		cp[3] = cp[7];
  		cp[4] = TO_IC;
  		cp[5] = TO_SBA;
  		cp[6] = 0x40;
  		cp[7] = 0x40;
  		fp->init->rescnt = 0;
  		fp->init->callback = fs3270_restore_callback;
  	}
  	rc = fp->init->rc = raw3270_start_locked(view, fp->init);
  	if (rc)
  		fp->init->callback(fp->init, NULL);
  	else
  		fp->active = 1;
  	return rc;
  }
  
  /*
   * Shutdown fullscreen view.
   */
  static void
  fs3270_save_callback(struct raw3270_request *rq, void *data)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) rq->view;
  
  	/* Correct idal buffer element 0 address. */
  	fp->rdbuf->data[0] -= 5;
  	fp->rdbuf->size += 5;
  
  	/*
  	 * If the rdbuf command failed or the idal buffer is
  	 * to small for the amount of data returned by the
  	 * rdbuf command, then we have no choice but to send
  	 * a SIGHUP to the application.
  	 */
  	if (rq->rc != 0 || rq->rescnt == 0) {
  		if (fp->fs_pid)
  			kill_pid(fp->fs_pid, SIGHUP, 1);
  		fp->rdbuf_size = 0;
  	} else
  		fp->rdbuf_size = fp->rdbuf->size - rq->rescnt;
  	raw3270_request_reset(rq);
  	wake_up(&fp->wait);
  }
  
  static void
  fs3270_deactivate(struct raw3270_view *view)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) view;
  	fp->active = 0;
  
  	/* If an old init command is still running just return. */
  	if (!raw3270_request_final(fp->init))
  		return;
  
  	/* Prepare read-buffer request. */
  	raw3270_request_set_cmd(fp->init, TC_RDBUF);
  	/*
  	 * Hackish: skip first 5 bytes of the idal buffer to make
  	 * room for the TW_KR/TO_SBA/<address>/<address>/TO_IC sequence
  	 * in the activation command.
  	 */
  	fp->rdbuf->data[0] += 5;
  	fp->rdbuf->size -= 5;
  	raw3270_request_set_idal(fp->init, fp->rdbuf);
  	fp->init->rescnt = 0;
  	fp->init->callback = fs3270_save_callback;
  
  	/* Start I/O to read in the 3270 buffer. */
  	fp->init->rc = raw3270_start_locked(view, fp->init);
  	if (fp->init->rc)
  		fp->init->callback(fp->init, NULL);
  }
  
  static int
  fs3270_irq(struct fs3270 *fp, struct raw3270_request *rq, struct irb *irb)
  {
  	/* Handle ATTN. Set indication and wake waiters for attention. */
  	if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION) {
  		fp->attention = 1;
  		wake_up(&fp->wait);
  	}
  
  	if (rq) {
  		if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK)
  			rq->rc = -EIO;
  		else
  			/* Normal end. Copy residual count. */
  			rq->rescnt = irb->scsw.cmd.count;
  	}
  	return RAW3270_IO_DONE;
  }
  
  /*
   * Process reads from fullscreen 3270.
   */
  static ssize_t
  fs3270_read(struct file *filp, char __user *data, size_t count, loff_t *off)
  {
  	struct fs3270 *fp;
  	struct raw3270_request *rq;
  	struct idal_buffer *ib;
  	ssize_t rc;
  	
  	if (count == 0 || count > 65535)
  		return -EINVAL;
  	fp = filp->private_data;
  	if (!fp)
  		return -ENODEV;
  	ib = idal_buffer_alloc(count, 0);
  	if (IS_ERR(ib))
  		return -ENOMEM;
  	rq = raw3270_request_alloc(0);
  	if (!IS_ERR(rq)) {
  		if (fp->read_command == 0 && fp->write_command != 0)
  			fp->read_command = 6;
  		raw3270_request_set_cmd(rq, fp->read_command ? : 2);
  		raw3270_request_set_idal(rq, ib);
  		rc = wait_event_interruptible(fp->wait, fp->attention);
  		fp->attention = 0;
  		if (rc == 0) {
  			rc = fs3270_do_io(&fp->view, rq);
  			if (rc == 0) {
  				count -= rq->rescnt;
  				if (idal_buffer_to_user(ib, data, count) != 0)
  					rc = -EFAULT;
  				else
  					rc = count;
  
  			}
  		}
  		raw3270_request_free(rq);
  	} else
  		rc = PTR_ERR(rq);
  	idal_buffer_free(ib);
  	return rc;
  }
  
  /*
   * Process writes to fullscreen 3270.
   */
  static ssize_t
  fs3270_write(struct file *filp, const char __user *data, size_t count, loff_t *off)
  {
  	struct fs3270 *fp;
  	struct raw3270_request *rq;
  	struct idal_buffer *ib;
  	int write_command;
  	ssize_t rc;
  
  	fp = filp->private_data;
  	if (!fp)
  		return -ENODEV;
  	ib = idal_buffer_alloc(count, 0);
  	if (IS_ERR(ib))
  		return -ENOMEM;
  	rq = raw3270_request_alloc(0);
  	if (!IS_ERR(rq)) {
  		if (idal_buffer_from_user(ib, data, count) == 0) {
  			write_command = fp->write_command ? : 1;
  			if (write_command == 5)
  				write_command = 13;
  			raw3270_request_set_cmd(rq, write_command);
  			raw3270_request_set_idal(rq, ib);
  			rc = fs3270_do_io(&fp->view, rq);
  			if (rc == 0)
  				rc = count - rq->rescnt;
  		} else
  			rc = -EFAULT;
  		raw3270_request_free(rq);
  	} else
  		rc = PTR_ERR(rq);
  	idal_buffer_free(ib);
  	return rc;
  }
  
  /*
   * process ioctl commands for the tube driver
   */
  static long
  fs3270_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  {
  	char __user *argp;
  	struct fs3270 *fp;
  	struct raw3270_iocb iocb;
  	int rc;
  
  	fp = filp->private_data;
  	if (!fp)
  		return -ENODEV;
  	if (is_compat_task())
  		argp = compat_ptr(arg);
  	else
  		argp = (char __user *)arg;
  	rc = 0;
  	mutex_lock(&fs3270_mutex);
  	switch (cmd) {
  	case TUBICMD:
  		fp->read_command = arg;
  		break;
  	case TUBOCMD:
  		fp->write_command = arg;
  		break;
  	case TUBGETI:
  		rc = put_user(fp->read_command, argp);
  		break;
  	case TUBGETO:
  		rc = put_user(fp->write_command, argp);
  		break;
  	case TUBGETMOD:
  		iocb.model = fp->view.model;
  		iocb.line_cnt = fp->view.rows;
  		iocb.col_cnt = fp->view.cols;
  		iocb.pf_cnt = 24;
  		iocb.re_cnt = 20;
  		iocb.map = 0;
  		if (copy_to_user(argp, &iocb, sizeof(struct raw3270_iocb)))
  			rc = -EFAULT;
  		break;
  	}
  	mutex_unlock(&fs3270_mutex);
  	return rc;
  }
  
  /*
   * Allocate fs3270 structure.
   */
  static struct fs3270 *
  fs3270_alloc_view(void)
  {
  	struct fs3270 *fp;
  
  	fp = kzalloc(sizeof(struct fs3270),GFP_KERNEL);
  	if (!fp)
  		return ERR_PTR(-ENOMEM);
  	fp->init = raw3270_request_alloc(0);
  	if (IS_ERR(fp->init)) {
  		kfree(fp);
  		return ERR_PTR(-ENOMEM);
  	}
  	return fp;
  }
  
  /*
   * Free fs3270 structure.
   */
  static void
  fs3270_free_view(struct raw3270_view *view)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) view;
  	if (fp->rdbuf)
  		idal_buffer_free(fp->rdbuf);
  	raw3270_request_free(((struct fs3270 *) view)->init);
  	kfree(view);
  }
  
  /*
   * Unlink fs3270 data structure from filp.
   */
  static void
  fs3270_release(struct raw3270_view *view)
  {
  	struct fs3270 *fp;
  
  	fp = (struct fs3270 *) view;
  	if (fp->fs_pid)
  		kill_pid(fp->fs_pid, SIGHUP, 1);
  }
  
  /* View to a 3270 device. Can be console, tty or fullscreen. */
  static struct raw3270_fn fs3270_fn = {
  	.activate = fs3270_activate,
  	.deactivate = fs3270_deactivate,
  	.intv = (void *) fs3270_irq,
  	.release = fs3270_release,
  	.free = fs3270_free_view
  };
  
  /*
   * This routine is called whenever a 3270 fullscreen device is opened.
   */
  static int
  fs3270_open(struct inode *inode, struct file *filp)
  {
  	struct fs3270 *fp;
  	struct idal_buffer *ib;
  	int minor, rc = 0;
  
  	if (imajor(file_inode(filp)) != IBM_FS3270_MAJOR)
  		return -ENODEV;
  	minor = iminor(file_inode(filp));
  	/* Check for minor 0 multiplexer. */
  	if (minor == 0) {
  		struct tty_struct *tty = get_current_tty();
  		if (!tty || tty->driver->major != IBM_TTY3270_MAJOR) {
  			tty_kref_put(tty);
  			return -ENODEV;
  		}
  		minor = tty->index;
  		tty_kref_put(tty);
  	}
  	mutex_lock(&fs3270_mutex);
  	/* Check if some other program is already using fullscreen mode. */
  	fp = (struct fs3270 *) raw3270_find_view(&fs3270_fn, minor);
  	if (!IS_ERR(fp)) {
  		raw3270_put_view(&fp->view);
  		rc = -EBUSY;
  		goto out;
  	}
  	/* Allocate fullscreen view structure. */
  	fp = fs3270_alloc_view();
  	if (IS_ERR(fp)) {
  		rc = PTR_ERR(fp);
  		goto out;
  	}
  
  	init_waitqueue_head(&fp->wait);
  	fp->fs_pid = get_pid(task_pid(current));
  	rc = raw3270_add_view(&fp->view, &fs3270_fn, minor);
  	if (rc) {
  		fs3270_free_view(&fp->view);
  		goto out;
  	}
  
  	/* Allocate idal-buffer. */
  	ib = idal_buffer_alloc(2*fp->view.rows*fp->view.cols + 5, 0);
  	if (IS_ERR(ib)) {
  		raw3270_put_view(&fp->view);
  		raw3270_del_view(&fp->view);
  		rc = PTR_ERR(ib);
  		goto out;
  	}
  	fp->rdbuf = ib;
  
  	rc = raw3270_activate_view(&fp->view);
  	if (rc) {
  		raw3270_put_view(&fp->view);
  		raw3270_del_view(&fp->view);
  		goto out;
  	}
  	nonseekable_open(inode, filp);
  	filp->private_data = fp;
  out:
  	mutex_unlock(&fs3270_mutex);
  	return rc;
  }
  
  /*
   * This routine is called when the 3270 tty is closed. We wait
   * for the remaining request to be completed. Then we clean up.
   */
  static int
  fs3270_close(struct inode *inode, struct file *filp)
  {
  	struct fs3270 *fp;
  
  	fp = filp->private_data;
  	filp->private_data = NULL;
  	if (fp) {
  		put_pid(fp->fs_pid);
  		fp->fs_pid = NULL;
  		raw3270_reset(&fp->view);
  		raw3270_put_view(&fp->view);
  		raw3270_del_view(&fp->view);
  	}
  	return 0;
  }
  
  static const struct file_operations fs3270_fops = {
  	.owner		 = THIS_MODULE,		/* owner */
  	.read		 = fs3270_read,		/* read */
  	.write		 = fs3270_write,	/* write */
  	.unlocked_ioctl	 = fs3270_ioctl,	/* ioctl */
  	.compat_ioctl	 = fs3270_ioctl,	/* ioctl */
  	.open		 = fs3270_open,		/* open */
  	.release	 = fs3270_close,	/* release */
  	.llseek		= no_llseek,
  };
  
  static void fs3270_create_cb(int minor)
  {
  	__register_chrdev(IBM_FS3270_MAJOR, minor, 1, "tub", &fs3270_fops);
  	device_create(class3270, NULL, MKDEV(IBM_FS3270_MAJOR, minor),
  		      NULL, "3270/tub%d", minor);
  }
  
  static void fs3270_destroy_cb(int minor)
  {
  	device_destroy(class3270, MKDEV(IBM_FS3270_MAJOR, minor));
  	__unregister_chrdev(IBM_FS3270_MAJOR, minor, 1, "tub");
  }
  
  static struct raw3270_notifier fs3270_notifier =
  {
  	.create = fs3270_create_cb,
  	.destroy = fs3270_destroy_cb,
  };
  
  /*
   * 3270 fullscreen driver initialization.
   */
  static int __init
  fs3270_init(void)
  {
  	int rc;
  
  	rc = __register_chrdev(IBM_FS3270_MAJOR, 0, 1, "fs3270", &fs3270_fops);
  	if (rc)
  		return rc;
  	device_create(class3270, NULL, MKDEV(IBM_FS3270_MAJOR, 0),
  		      NULL, "3270/tub");
  	raw3270_register_notifier(&fs3270_notifier);
  	return 0;
  }
  
  static void __exit
  fs3270_exit(void)
  {
  	raw3270_unregister_notifier(&fs3270_notifier);
  	device_destroy(class3270, MKDEV(IBM_FS3270_MAJOR, 0));
  	__unregister_chrdev(IBM_FS3270_MAJOR, 0, 1, "fs3270");
  }
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_CHARDEV_MAJOR(IBM_FS3270_MAJOR);
  
  module_init(fs3270_init);
  module_exit(fs3270_exit);