text: /*
   * Character device driver for reading z/VM *MONITOR service records.
   *
   * Copyright IBM Corp. 2004, 2009
   *
   * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
   */
  
  #define KMSG_COMPONENT "monreader"
  #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/spinlock.h>
  #include <linux/interrupt.h>
  #include <linux/poll.h>
  #include <linux/device.h>
  #include <linux/slab.h>
  #include <net/iucv/iucv.h>
  #include <asm/uaccess.h>
  #include <asm/ebcdic.h>
  #include <asm/extmem.h>
  
  
  #define MON_COLLECT_SAMPLE 0x80
  #define MON_COLLECT_EVENT  0x40
  #define MON_SERVICE	   "*MONITOR"
  #define MON_IN_USE	   0x01
  #define MON_MSGLIM	   255
  
  static char mon_dcss_name[9] = "MONDCSS\0";
  
  struct mon_msg {
  	u32 pos;
  	u32 mca_offset;
  	struct iucv_message msg;
  	char msglim_reached;
  	char replied_msglim;
  };
  
  struct mon_private {
  	struct iucv_path *path;
  	struct mon_msg *msg_array[MON_MSGLIM];
  	unsigned int   write_index;
  	unsigned int   read_index;
  	atomic_t msglim_count;
  	atomic_t read_ready;
  	atomic_t iucv_connected;
  	atomic_t iucv_severed;
  };
  
  static unsigned long mon_in_use = 0;
  
  static unsigned long mon_dcss_start;
  static unsigned long mon_dcss_end;
  
  static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  
  static u8 user_data_connect[16] = {
  	/* Version code, must be 0x01 for shared mode */
  	0x01,
  	/* what to collect */
  	MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
  	/* DCSS name in EBCDIC, 8 bytes padded with blanks */
  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  };
  
  static u8 user_data_sever[16] = {
  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  };
  
  static struct device *monreader_device;
  
  /******************************************************************************
   *                             helper functions                               *
   *****************************************************************************/
  /*
   * Create the 8 bytes EBCDIC DCSS segment name from
   * an ASCII name, incl. padding
   */
  static void dcss_mkname(char *ascii_name, char *ebcdic_name)
  {
  	int i;
  
  	for (i = 0; i < 8; i++) {
  		if (ascii_name[i] == '\0')
  			break;
  		ebcdic_name[i] = toupper(ascii_name[i]);
  	}
  	for (; i < 8; i++)
  		ebcdic_name[i] = ' ';
  	ASCEBC(ebcdic_name, 8);
  }
  
  static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
  {
  	return *(u32 *) &monmsg->msg.rmmsg;
  }
  
  static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
  {
  	return *(u32 *) &monmsg->msg.rmmsg[4];
  }
  
  static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
  {
  	return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
  }
  
  static inline u32 mon_mca_size(struct mon_msg *monmsg)
  {
  	return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
  }
  
  static inline u32 mon_rec_start(struct mon_msg *monmsg)
  {
  	return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
  }
  
  static inline u32 mon_rec_end(struct mon_msg *monmsg)
  {
  	return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
  }
  
  static int mon_check_mca(struct mon_msg *monmsg)
  {
  	if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
  	    (mon_rec_start(monmsg) < mon_dcss_start) ||
  	    (mon_rec_end(monmsg) > mon_dcss_end) ||
  	    (mon_mca_type(monmsg, 0) == 0) ||
  	    (mon_mca_size(monmsg) % 12 != 0) ||
  	    (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
  	    (mon_mca_end(monmsg) > mon_dcss_end) ||
  	    (mon_mca_start(monmsg) < mon_dcss_start) ||
  	    ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
  		return -EINVAL;
  	return 0;
  }
  
  static int mon_send_reply(struct mon_msg *monmsg,
  			  struct mon_private *monpriv)
  {
  	int rc;
  
  	rc = iucv_message_reply(monpriv->path, &monmsg->msg,
  				IUCV_IPRMDATA, NULL, 0);
  	atomic_dec(&monpriv->msglim_count);
  	if (likely(!monmsg->msglim_reached)) {
  		monmsg->pos = 0;
  		monmsg->mca_offset = 0;
  		monpriv->read_index = (monpriv->read_index + 1) %
  				      MON_MSGLIM;
  		atomic_dec(&monpriv->read_ready);
  	} else
  		monmsg->replied_msglim = 1;
  	if (rc) {
  		pr_err("Reading monitor data failed with rc=%i\n", rc);
  		return -EIO;
  	}
  	return 0;
  }
  
  static void mon_free_mem(struct mon_private *monpriv)
  {
  	int i;
  
  	for (i = 0; i < MON_MSGLIM; i++)
  		kfree(monpriv->msg_array[i]);
  	kfree(monpriv);
  }
  
  static struct mon_private *mon_alloc_mem(void)
  {
  	int i;
  	struct mon_private *monpriv;
  
  	monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
  	if (!monpriv)
  		return NULL;
  	for (i = 0; i < MON_MSGLIM; i++) {
  		monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
  						    GFP_KERNEL);
  		if (!monpriv->msg_array[i]) {
  			mon_free_mem(monpriv);
  			return NULL;
  		}
  	}
  	return monpriv;
  }
  
  static inline void mon_next_mca(struct mon_msg *monmsg)
  {
  	if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
  		return;
  	monmsg->mca_offset += 12;
  	monmsg->pos = 0;
  }
  
  static struct mon_msg *mon_next_message(struct mon_private *monpriv)
  {
  	struct mon_msg *monmsg;
  
  	if (!atomic_read(&monpriv->read_ready))
  		return NULL;
  	monmsg = monpriv->msg_array[monpriv->read_index];
  	if (unlikely(monmsg->replied_msglim)) {
  		monmsg->replied_msglim = 0;
  		monmsg->msglim_reached = 0;
  		monmsg->pos = 0;
  		monmsg->mca_offset = 0;
  		monpriv->read_index = (monpriv->read_index + 1) %
  				      MON_MSGLIM;
  		atomic_dec(&monpriv->read_ready);
  		return ERR_PTR(-EOVERFLOW);
  	}
  	return monmsg;
  }
  
  
  /******************************************************************************
   *                               IUCV handler                                 *
   *****************************************************************************/
  static void mon_iucv_path_complete(struct iucv_path *path, u8 ipuser[16])
  {
  	struct mon_private *monpriv = path->private;
  
  	atomic_set(&monpriv->iucv_connected, 1);
  	wake_up(&mon_conn_wait_queue);
  }
  
  static void mon_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
  {
  	struct mon_private *monpriv = path->private;
  
  	pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
  	       ipuser[0]);
  	iucv_path_sever(path, NULL);
  	atomic_set(&monpriv->iucv_severed, 1);
  	wake_up(&mon_conn_wait_queue);
  	wake_up_interruptible(&mon_read_wait_queue);
  }
  
  static void mon_iucv_message_pending(struct iucv_path *path,
  				     struct iucv_message *msg)
  {
  	struct mon_private *monpriv = path->private;
  
  	memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
  	       msg, sizeof(*msg));
  	if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
  		pr_warning("The read queue for monitor data is full\n");
  		monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
  	}
  	monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
  	atomic_inc(&monpriv->read_ready);
  	wake_up_interruptible(&mon_read_wait_queue);
  }
  
  static struct iucv_handler monreader_iucv_handler = {
  	.path_complete	 = mon_iucv_path_complete,
  	.path_severed	 = mon_iucv_path_severed,
  	.message_pending = mon_iucv_message_pending,
  };
  
  /******************************************************************************
   *                               file operations                              *
   *****************************************************************************/
  static int mon_open(struct inode *inode, struct file *filp)
  {
  	struct mon_private *monpriv;
  	int rc;
  
  	/*
  	 * only one user allowed
  	 */
  	rc = -EBUSY;
  	if (test_and_set_bit(MON_IN_USE, &mon_in_use))
  		goto out;
  
  	rc = -ENOMEM;
  	monpriv = mon_alloc_mem();
  	if (!monpriv)
  		goto out_use;
  
  	/*
  	 * Connect to *MONITOR service
  	 */
  	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
  	if (!monpriv->path)
  		goto out_priv;
  	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
  			       MON_SERVICE, NULL, user_data_connect, monpriv);
  	if (rc) {
  		pr_err("Connecting to the z/VM *MONITOR system service "
  		       "failed with rc=%i\n", rc);
  		rc = -EIO;
  		goto out_path;
  	}
  	/*
  	 * Wait for connection confirmation
  	 */
  	wait_event(mon_conn_wait_queue,
  		   atomic_read(&monpriv->iucv_connected) ||
  		   atomic_read(&monpriv->iucv_severed));
  	if (atomic_read(&monpriv->iucv_severed)) {
  		atomic_set(&monpriv->iucv_severed, 0);
  		atomic_set(&monpriv->iucv_connected, 0);
  		rc = -EIO;
  		goto out_path;
  	}
  	filp->private_data = monpriv;
  	dev_set_drvdata(monreader_device, monpriv);
  	return nonseekable_open(inode, filp);
  
  out_path:
  	iucv_path_free(monpriv->path);
  out_priv:
  	mon_free_mem(monpriv);
  out_use:
  	clear_bit(MON_IN_USE, &mon_in_use);
  out:
  	return rc;
  }
  
  static int mon_close(struct inode *inode, struct file *filp)
  {
  	int rc, i;
  	struct mon_private *monpriv = filp->private_data;
  
  	/*
  	 * Close IUCV connection and unregister
  	 */
  	if (monpriv->path) {
  		rc = iucv_path_sever(monpriv->path, user_data_sever);
  		if (rc)
  			pr_warning("Disconnecting the z/VM *MONITOR system "
  				   "service failed with rc=%i\n", rc);
  		iucv_path_free(monpriv->path);
  	}
  
  	atomic_set(&monpriv->iucv_severed, 0);
  	atomic_set(&monpriv->iucv_connected, 0);
  	atomic_set(&monpriv->read_ready, 0);
  	atomic_set(&monpriv->msglim_count, 0);
  	monpriv->write_index  = 0;
  	monpriv->read_index   = 0;
  	dev_set_drvdata(monreader_device, NULL);
  
  	for (i = 0; i < MON_MSGLIM; i++)
  		kfree(monpriv->msg_array[i]);
  	kfree(monpriv);
  	clear_bit(MON_IN_USE, &mon_in_use);
  	return 0;
  }
  
  static ssize_t mon_read(struct file *filp, char __user *data,
  			size_t count, loff_t *ppos)
  {
  	struct mon_private *monpriv = filp->private_data;
  	struct mon_msg *monmsg;
  	int ret;
  	u32 mce_start;
  
  	monmsg = mon_next_message(monpriv);
  	if (IS_ERR(monmsg))
  		return PTR_ERR(monmsg);
  
  	if (!monmsg) {
  		if (filp->f_flags & O_NONBLOCK)
  			return -EAGAIN;
  		ret = wait_event_interruptible(mon_read_wait_queue,
  					atomic_read(&monpriv->read_ready) ||
  					atomic_read(&monpriv->iucv_severed));
  		if (ret)
  			return ret;
  		if (unlikely(atomic_read(&monpriv->iucv_severed)))
  			return -EIO;
  		monmsg = monpriv->msg_array[monpriv->read_index];
  	}
  
  	if (!monmsg->pos)
  		monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
  	if (mon_check_mca(monmsg))
  		goto reply;
  
  	/* read monitor control element (12 bytes) first */
  	mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
  	if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
  		count = min(count, (size_t) mce_start + 12 - monmsg->pos);
  		ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
  				   count);
  		if (ret)
  			return -EFAULT;
  		monmsg->pos += count;
  		if (monmsg->pos == mce_start + 12)
  			monmsg->pos = mon_rec_start(monmsg);
  		goto out_copy;
  	}
  
  	/* read records */
  	if (monmsg->pos <= mon_rec_end(monmsg)) {
  		count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
  					    + 1);
  		ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
  				   count);
  		if (ret)
  			return -EFAULT;
  		monmsg->pos += count;
  		if (monmsg->pos > mon_rec_end(monmsg))
  			mon_next_mca(monmsg);
  		goto out_copy;
  	}
  reply:
  	ret = mon_send_reply(monmsg, monpriv);
  	return ret;
  
  out_copy:
  	*ppos += count;
  	return count;
  }
  
  static unsigned int mon_poll(struct file *filp, struct poll_table_struct *p)
  {
  	struct mon_private *monpriv = filp->private_data;
  
  	poll_wait(filp, &mon_read_wait_queue, p);
  	if (unlikely(atomic_read(&monpriv->iucv_severed)))
  		return POLLERR;
  	if (atomic_read(&monpriv->read_ready))
  		return POLLIN | POLLRDNORM;
  	return 0;
  }
  
  static const struct file_operations mon_fops = {
  	.owner   = THIS_MODULE,
  	.open    = &mon_open,
  	.release = &mon_close,
  	.read    = &mon_read,
  	.poll    = &mon_poll,
  	.llseek  = noop_llseek,
  };
  
  static struct miscdevice mon_dev = {
  	.name       = "monreader",
  	.fops       = &mon_fops,
  	.minor      = MISC_DYNAMIC_MINOR,
  };
  
  
  /******************************************************************************
   *				suspend / resume			      *
   *****************************************************************************/
  static int monreader_freeze(struct device *dev)
  {
  	struct mon_private *monpriv = dev_get_drvdata(dev);
  	int rc;
  
  	if (!monpriv)
  		return 0;
  	if (monpriv->path) {
  		rc = iucv_path_sever(monpriv->path, user_data_sever);
  		if (rc)
  			pr_warning("Disconnecting the z/VM *MONITOR system "
  				   "service failed with rc=%i\n", rc);
  		iucv_path_free(monpriv->path);
  	}
  	atomic_set(&monpriv->iucv_severed, 0);
  	atomic_set(&monpriv->iucv_connected, 0);
  	atomic_set(&monpriv->read_ready, 0);
  	atomic_set(&monpriv->msglim_count, 0);
  	monpriv->write_index  = 0;
  	monpriv->read_index   = 0;
  	monpriv->path = NULL;
  	return 0;
  }
  
  static int monreader_thaw(struct device *dev)
  {
  	struct mon_private *monpriv = dev_get_drvdata(dev);
  	int rc;
  
  	if (!monpriv)
  		return 0;
  	rc = -ENOMEM;
  	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
  	if (!monpriv->path)
  		goto out;
  	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
  			       MON_SERVICE, NULL, user_data_connect, monpriv);
  	if (rc) {
  		pr_err("Connecting to the z/VM *MONITOR system service "
  		       "failed with rc=%i\n", rc);
  		goto out_path;
  	}
  	wait_event(mon_conn_wait_queue,
  		   atomic_read(&monpriv->iucv_connected) ||
  		   atomic_read(&monpriv->iucv_severed));
  	if (atomic_read(&monpriv->iucv_severed))
  		goto out_path;
  	return 0;
  out_path:
  	rc = -EIO;
  	iucv_path_free(monpriv->path);
  	monpriv->path = NULL;
  out:
  	atomic_set(&monpriv->iucv_severed, 1);
  	return rc;
  }
  
  static int monreader_restore(struct device *dev)
  {
  	int rc;
  
  	segment_unload(mon_dcss_name);
  	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
  			  &mon_dcss_start, &mon_dcss_end);
  	if (rc < 0) {
  		segment_warning(rc, mon_dcss_name);
  		panic("fatal monreader resume error: no monitor dcss\n");
  	}
  	return monreader_thaw(dev);
  }
  
  static const struct dev_pm_ops monreader_pm_ops = {
  	.freeze  = monreader_freeze,
  	.thaw	 = monreader_thaw,
  	.restore = monreader_restore,
  };
  
  static struct device_driver monreader_driver = {
  	.name = "monreader",
  	.bus  = &iucv_bus,
  	.pm   = &monreader_pm_ops,
  };
  
  
  /******************************************************************************
   *                              module init/exit                              *
   *****************************************************************************/
  static int __init mon_init(void)
  {
  	int rc;
  
  	if (!MACHINE_IS_VM) {
  		pr_err("The z/VM *MONITOR record device driver cannot be "
  		       "loaded without z/VM\n");
  		return -ENODEV;
  	}
  
  	/*
  	 * Register with IUCV and connect to *MONITOR service
  	 */
  	rc = iucv_register(&monreader_iucv_handler, 1);
  	if (rc) {
  		pr_err("The z/VM *MONITOR record device driver failed to "
  		       "register with IUCV\n");
  		return rc;
  	}
  
  	rc = driver_register(&monreader_driver);
  	if (rc)
  		goto out_iucv;
  	monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
  	if (!monreader_device) {
  		rc = -ENOMEM;
  		goto out_driver;
  	}
  
  	dev_set_name(monreader_device, "monreader-dev");
  	monreader_device->bus = &iucv_bus;
  	monreader_device->parent = iucv_root;
  	monreader_device->driver = &monreader_driver;
  	monreader_device->release = (void (*)(struct device *))kfree;
  	rc = device_register(monreader_device);
  	if (rc) {
  		put_device(monreader_device);
  		goto out_driver;
  	}
  
  	rc = segment_type(mon_dcss_name);
  	if (rc < 0) {
  		segment_warning(rc, mon_dcss_name);
  		goto out_device;
  	}
  	if (rc != SEG_TYPE_SC) {
  		pr_err("The specified *MONITOR DCSS %s does not have the "
  		       "required type SC\n", mon_dcss_name);
  		rc = -EINVAL;
  		goto out_device;
  	}
  
  	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
  			  &mon_dcss_start, &mon_dcss_end);
  	if (rc < 0) {
  		segment_warning(rc, mon_dcss_name);
  		rc = -EINVAL;
  		goto out_device;
  	}
  	dcss_mkname(mon_dcss_name, &user_data_connect[8]);
  
  	/*
  	 * 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 < 0 )
  		goto out;
  	return 0;
  
  out:
  	segment_unload(mon_dcss_name);
  out_device:
  	device_unregister(monreader_device);
  out_driver:
  	driver_unregister(&monreader_driver);
  out_iucv:
  	iucv_unregister(&monreader_iucv_handler, 1);
  	return rc;
  }
  
  static void __exit mon_exit(void)
  {
  	segment_unload(mon_dcss_name);
  	misc_deregister(&mon_dev);
  	device_unregister(monreader_device);
  	driver_unregister(&monreader_driver);
  	iucv_unregister(&monreader_iucv_handler, 1);
  	return;
  }
  
  
  module_init(mon_init);
  module_exit(mon_exit);
  
  module_param_string(mondcss, mon_dcss_name, 9, 0444);
  MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
  		 "service, max. 8 chars. Default is MONDCSS");
  
  MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
  MODULE_DESCRIPTION("Character device driver for reading z/VM "
  		   "monitor service records.");
  MODULE_LICENSE("GPL");
  