drivers/s390/char/monreader.c - kernel/msm-4.19 - Gitiles

 /*
  * 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/smp_lock.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 <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++)
 		if (monpriv->msg_array[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
 	 */
 	lock_kernel();
 	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);
 	unlock_kernel();
 	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:
 	unlock_kernel();
 	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,
 };

 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 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)
 		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]);

 	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);
 	WARN_ON(misc_deregister(&mon_dev) != 0);
 	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");
	/*
	* 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/smp_lock.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 <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++)
	if (monpriv->msg_array[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
	*/
	lock_kernel();
	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);
	unlock_kernel();
	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:
	unlock_kernel();
	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,
	};

	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 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)
	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]);

	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);
	WARN_ON(misc_deregister(&mon_dev) != 0);
	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");