/*
   * Character device driver for writing z/VM *MONITOR service records.
   *
   * Copyright IBM Corp. 2006, 2009
   *
   * Author(s): Melissa Howland <Melissa.Howland@us.ibm.com>
   */
  
  #define KMSG_COMPONENT "monwriter"
  #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/init.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/miscdevice.h>
  #include <linux/ctype.h>
  #include <linux/poll.h>
  #include <linux/mutex.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <asm/uaccess.h>
  #include <asm/ebcdic.h>
  #include <asm/io.h>
  #include <asm/appldata.h>
  #include <asm/monwriter.h>
  
  #define MONWRITE_MAX_DATALEN	4010
  
  static int mon_max_bufs = 255;
  static int mon_buf_count;
  
  struct mon_buf {
  	struct list_head list;
  	struct monwrite_hdr hdr;
  	int diag_done;
  	char *data;
  };
  
  static LIST_HEAD(mon_priv_list);
  
  struct mon_private {
  	struct list_head priv_list;
  	struct list_head list;
  	struct monwrite_hdr hdr;
  	size_t hdr_to_read;
  	size_t data_to_read;
  	struct mon_buf *current_buf;
  	struct mutex thread_mutex;
  };
  
  /*
   * helper functions
   */
  
  static int monwrite_diag(struct monwrite_hdr *myhdr, char *buffer, int fcn)
  {
  	struct appldata_product_id id;
  	int rc;
  
  	strncpy(id.prod_nr, "LNXAPPL", 7);
  	id.prod_fn = myhdr->applid;
  	id.record_nr = myhdr->record_num;
  	id.version_nr = myhdr->version;
  	id.release_nr = myhdr->release;
  	id.mod_lvl = myhdr->mod_level;
  	rc = appldata_asm(&id, fcn, (void *) buffer, myhdr->datalen);
  	if (rc <= 0)
  		return rc;
  	pr_err("Writing monitor data failed with rc=%i
  ", rc);
  	if (rc == 5)
  		return -EPERM;
  	return -EINVAL;
  }
  
  static struct mon_buf *monwrite_find_hdr(struct mon_private *monpriv,
  					 struct monwrite_hdr *monhdr)
  {
  	struct mon_buf *entry, *next;
  
  	list_for_each_entry_safe(entry, next, &monpriv->list, list)
  		if ((entry->hdr.mon_function == monhdr->mon_function ||
  		     monhdr->mon_function == MONWRITE_STOP_INTERVAL) &&
  		    entry->hdr.applid == monhdr->applid &&
  		    entry->hdr.record_num == monhdr->record_num &&
  		    entry->hdr.version == monhdr->version &&
  		    entry->hdr.release == monhdr->release &&
  		    entry->hdr.mod_level == monhdr->mod_level)
  			return entry;
  
  	return NULL;
  }
  
  static int monwrite_new_hdr(struct mon_private *monpriv)
  {
  	struct monwrite_hdr *monhdr = &monpriv->hdr;
  	struct mon_buf *monbuf;
  	int rc = 0;
  
  	if (monhdr->datalen > MONWRITE_MAX_DATALEN ||
  	    monhdr->mon_function > MONWRITE_START_CONFIG ||
  	    monhdr->hdrlen != sizeof(struct monwrite_hdr))
  		return -EINVAL;
  	monbuf = NULL;
  	if (monhdr->mon_function != MONWRITE_GEN_EVENT)
  		monbuf = monwrite_find_hdr(monpriv, monhdr);
  	if (monbuf) {
  		if (monhdr->mon_function == MONWRITE_STOP_INTERVAL) {
  			monhdr->datalen = monbuf->hdr.datalen;
  			rc = monwrite_diag(monhdr, monbuf->data,
  					   APPLDATA_STOP_REC);
  			list_del(&monbuf->list);
  			mon_buf_count--;
  			kfree(monbuf->data);
  			kfree(monbuf);
  			monbuf = NULL;
  		}
  	} else if (monhdr->mon_function != MONWRITE_STOP_INTERVAL) {
  		if (mon_buf_count >= mon_max_bufs)
  			return -ENOSPC;
  		monbuf = kzalloc(sizeof(struct mon_buf), GFP_KERNEL);
  		if (!monbuf)
  			return -ENOMEM;
  		monbuf->data = kzalloc(monhdr->datalen,
  				       GFP_KERNEL | GFP_DMA);
  		if (!monbuf->data) {
  			kfree(monbuf);
  			return -ENOMEM;
  		}
  		monbuf->hdr = *monhdr;
  		list_add_tail(&monbuf->list, &monpriv->list);
  		if (monhdr->mon_function != MONWRITE_GEN_EVENT)
  			mon_buf_count++;
  	}
  	monpriv->current_buf = monbuf;
  	return rc;
  }
  
  static int monwrite_new_data(struct mon_private *monpriv)
  {
  	struct monwrite_hdr *monhdr = &monpriv->hdr;
  	struct mon_buf *monbuf = monpriv->current_buf;
  	int rc = 0;
  
  	switch (monhdr->mon_function) {
  	case MONWRITE_START_INTERVAL:
  		if (!monbuf->diag_done) {
  			rc = monwrite_diag(monhdr, monbuf->data,
  					   APPLDATA_START_INTERVAL_REC);
  			monbuf->diag_done = 1;
  		}
  		break;
  	case MONWRITE_START_CONFIG:
  		if (!monbuf->diag_done) {
  			rc = monwrite_diag(monhdr, monbuf->data,
  					   APPLDATA_START_CONFIG_REC);
  			monbuf->diag_done = 1;
  		}
  		break;
  	case MONWRITE_GEN_EVENT:
  		rc = monwrite_diag(monhdr, monbuf->data,
  				   APPLDATA_GEN_EVENT_REC);
  		list_del(&monpriv->current_buf->list);
  		kfree(monpriv->current_buf->data);
  		kfree(monpriv->current_buf);
  		monpriv->current_buf = NULL;
  		break;
  	default:
  		/* monhdr->mon_function is checked in monwrite_new_hdr */
  		BUG();
  	}
  	return rc;
  }
  
  /*
   * file operations
   */
  
  static int monwrite_open(struct inode *inode, struct file *filp)
  {
  	struct mon_private *monpriv;
  
  	monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
  	if (!monpriv)
  		return -ENOMEM;
  	INIT_LIST_HEAD(&monpriv->list);
  	monpriv->hdr_to_read = sizeof(monpriv->hdr);
  	mutex_init(&monpriv->thread_mutex);
  	filp->private_data = monpriv;
  	list_add_tail(&monpriv->priv_list, &mon_priv_list);
  	return nonseekable_open(inode, filp);
  }
  
  static int monwrite_close(struct inode *inode, struct file *filp)
  {
  	struct mon_private *monpriv = filp->private_data;
  	struct mon_buf *entry, *next;
  
  	list_for_each_entry_safe(entry, next, &monpriv->list, list) {
  		if (entry->hdr.mon_function != MONWRITE_GEN_EVENT)
  			monwrite_diag(&entry->hdr, entry->data,
  				      APPLDATA_STOP_REC);
  		mon_buf_count--;
  		list_del(&entry->list);
  		kfree(entry->data);
  		kfree(entry);
  	}
  	list_del(&monpriv->priv_list);
  	kfree(monpriv);
  	return 0;
  }
  
  static ssize_t monwrite_write(struct file *filp, const char __user *data,
  			      size_t count, loff_t *ppos)
  {
  	struct mon_private *monpriv = filp->private_data;
  	size_t len, written;
  	void *to;
  	int rc;
  
  	mutex_lock(&monpriv->thread_mutex);
  	for (written = 0; written < count; ) {
  		if (monpriv->hdr_to_read) {
  			len = min(count - written, monpriv->hdr_to_read);
  			to = (char *) &monpriv->hdr +
  				sizeof(monpriv->hdr) - monpriv->hdr_to_read;
  			if (copy_from_user(to, data + written, len)) {
  				rc = -EFAULT;
  				goto out_error;
  			}
  			monpriv->hdr_to_read -= len;
  			written += len;
  			if (monpriv->hdr_to_read > 0)
  				continue;
  			rc = monwrite_new_hdr(monpriv);
  			if (rc)
  				goto out_error;
  			monpriv->data_to_read = monpriv->current_buf ?
  				monpriv->current_buf->hdr.datalen : 0;
  		}
  
  		if (monpriv->data_to_read) {
  			len = min(count - written, monpriv->data_to_read);
  			to = monpriv->current_buf->data +
  				monpriv->hdr.datalen - monpriv->data_to_read;
  			if (copy_from_user(to, data + written, len)) {
  				rc = -EFAULT;
  				goto out_error;
  			}
  			monpriv->data_to_read -= len;
  			written += len;
  			if (monpriv->data_to_read > 0)
  				continue;
  			rc = monwrite_new_data(monpriv);
  			if (rc)
  				goto out_error;
  		}
  		monpriv->hdr_to_read = sizeof(monpriv->hdr);
  	}
  	mutex_unlock(&monpriv->thread_mutex);
  	return written;
  
  out_error:
  	monpriv->data_to_read = 0;
  	monpriv->hdr_to_read = sizeof(struct monwrite_hdr);
  	mutex_unlock(&monpriv->thread_mutex);
  	return rc;
  }
  
  static const struct file_operations monwrite_fops = {
  	.owner	 = THIS_MODULE,
  	.open	 = &monwrite_open,
  	.release = &monwrite_close,
  	.write	 = &monwrite_write,
  	.llseek  = noop_llseek,
  };
  
  static struct miscdevice mon_dev = {
  	.name	= "monwriter",
  	.fops	= &monwrite_fops,
  	.minor	= MISC_DYNAMIC_MINOR,
  };
  
  /*
   * suspend/resume
   */
  
  static int monwriter_freeze(struct device *dev)
  {
  	struct mon_private *monpriv;
  	struct mon_buf *monbuf;
  
  	list_for_each_entry(monpriv, &mon_priv_list, priv_list) {
  		list_for_each_entry(monbuf, &monpriv->list, list) {
  			if (monbuf->hdr.mon_function != MONWRITE_GEN_EVENT)
  				monwrite_diag(&monbuf->hdr, monbuf->data,
  					      APPLDATA_STOP_REC);
  		}
  	}
  	return 0;
  }
  
  static int monwriter_restore(struct device *dev)
  {
  	struct mon_private *monpriv;
  	struct mon_buf *monbuf;
  
  	list_for_each_entry(monpriv, &mon_priv_list, priv_list) {
  		list_for_each_entry(monbuf, &monpriv->list, list) {
  			if (monbuf->hdr.mon_function == MONWRITE_START_INTERVAL)
  				monwrite_diag(&monbuf->hdr, monbuf->data,
  					      APPLDATA_START_INTERVAL_REC);
  			if (monbuf->hdr.mon_function == MONWRITE_START_CONFIG)
  				monwrite_diag(&monbuf->hdr, monbuf->data,
  					      APPLDATA_START_CONFIG_REC);
  		}
  	}
  	return 0;
  }
  
  static int monwriter_thaw(struct device *dev)
  {
  	return monwriter_restore(dev);
  }
  
  static const struct dev_pm_ops monwriter_pm_ops = {
  	.freeze		= monwriter_freeze,
  	.thaw		= monwriter_thaw,
  	.restore	= monwriter_restore,
  };
  
  static struct platform_driver monwriter_pdrv = {
  	.driver = {
  		.name	= "monwriter",
  		.owner	= THIS_MODULE,
  		.pm	= &monwriter_pm_ops,
  	},
  };
  
  static struct platform_device *monwriter_pdev;
  
  /*
   * module init/exit
   */
  
  static int __init mon_init(void)
  {
  	int rc;
  
  	if (!MACHINE_IS_VM)
  		return -ENODEV;
  
  	rc = platform_driver_register(&monwriter_pdrv);
  	if (rc)
  		return rc;
  
  	monwriter_pdev = platform_device_register_simple("monwriter", -1, NULL,
  							0);
  	if (IS_ERR(monwriter_pdev)) {
  		rc = PTR_ERR(monwriter_pdev);
  		goto out_driver;
  	}
  
  	/*
  	 * misc_register() has to be the last action in module_init(), because
  	 * file operations will be available right after this.
  	 */
  	rc = misc_register(&mon_dev);
  	if (rc)
  		goto out_device;
  	return 0;
  
  out_device:
  	platform_device_unregister(monwriter_pdev);
  out_driver:
  	platform_driver_unregister(&monwriter_pdrv);
  	return rc;
  }
  
  static void __exit mon_exit(void)
  {
  	misc_deregister(&mon_dev);
  	platform_device_unregister(monwriter_pdev);
  	platform_driver_unregister(&monwriter_pdrv);
  }
  
  module_init(mon_init);
  module_exit(mon_exit);
  
  module_param_named(max_bufs, mon_max_bufs, int, 0644);
  MODULE_PARM_DESC(max_bufs, "Maximum number of sample monitor data buffers "
  		 "that can be active at one time");
  
  MODULE_AUTHOR("Melissa Howland <Melissa.Howland@us.ibm.com>");
  MODULE_DESCRIPTION("Character device driver for writing z/VM "
  		   "APPLDATA monitor records.");
  MODULE_LICENSE("GPL");