text: /******************************************************************************
   * Talks to Xen Store to figure out what devices we have.
   *
   * Copyright (C) 2005 Rusty Russell, IBM Corporation
   * Copyright (C) 2005 Mike Wray, Hewlett-Packard
   * Copyright (C) 2005, 2006 XenSource Ltd
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version 2
   * as published by the Free Software Foundation; or, when distributed
   * separately from the Linux kernel or incorporated into other
   * software packages, subject to the following license:
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this source file (the "Software"), to deal in the Software without
   * restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software,
   * and to permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  #define DPRINTK(fmt, args...)				\
  	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
  		 __func__, __LINE__, ##args)
  
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/string.h>
  #include <linux/ctype.h>
  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/proc_fs.h>
  #include <linux/notifier.h>
  #include <linux/kthread.h>
  #include <linux/mutex.h>
  #include <linux/io.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  
  #include <asm/page.h>
  #include <asm/pgtable.h>
  #include <asm/xen/hypervisor.h>
  
  #include <xen/xen.h>
  #include <xen/xenbus.h>
  #include <xen/events.h>
  #include <xen/page.h>
  
  #include <xen/hvm.h>
  
  #include "xenbus_comms.h"
  #include "xenbus_probe.h"
  
  
  int xen_store_evtchn;
  EXPORT_SYMBOL_GPL(xen_store_evtchn);
  
  struct xenstore_domain_interface *xen_store_interface;
  EXPORT_SYMBOL_GPL(xen_store_interface);
  
  static unsigned long xen_store_mfn;
  
  static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  
  /* If something in array of ids matches this device, return it. */
  static const struct xenbus_device_id *
  match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  {
  	for (; *arr->devicetype != '\0'; arr++) {
  		if (!strcmp(arr->devicetype, dev->devicetype))
  			return arr;
  	}
  	return NULL;
  }
  
  int xenbus_match(struct device *_dev, struct device_driver *_drv)
  {
  	struct xenbus_driver *drv = to_xenbus_driver(_drv);
  
  	if (!drv->ids)
  		return 0;
  
  	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
  }
  EXPORT_SYMBOL_GPL(xenbus_match);
  
  
  static void free_otherend_details(struct xenbus_device *dev)
  {
  	kfree(dev->otherend);
  	dev->otherend = NULL;
  }
  
  
  static void free_otherend_watch(struct xenbus_device *dev)
  {
  	if (dev->otherend_watch.node) {
  		unregister_xenbus_watch(&dev->otherend_watch);
  		kfree(dev->otherend_watch.node);
  		dev->otherend_watch.node = NULL;
  	}
  }
  
  
  static int talk_to_otherend(struct xenbus_device *dev)
  {
  	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
  
  	free_otherend_watch(dev);
  	free_otherend_details(dev);
  
  	return drv->read_otherend_details(dev);
  }
  
  
  
  static int watch_otherend(struct xenbus_device *dev)
  {
  	struct xen_bus_type *bus =
  		container_of(dev->dev.bus, struct xen_bus_type, bus);
  
  	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
  				    bus->otherend_changed,
  				    "%s/%s", dev->otherend, "state");
  }
  
  
  int xenbus_read_otherend_details(struct xenbus_device *xendev,
  				 char *id_node, char *path_node)
  {
  	int err = xenbus_gather(XBT_NIL, xendev->nodename,
  				id_node, "%i", &xendev->otherend_id,
  				path_node, NULL, &xendev->otherend,
  				NULL);
  	if (err) {
  		xenbus_dev_fatal(xendev, err,
  				 "reading other end details from %s",
  				 xendev->nodename);
  		return err;
  	}
  	if (strlen(xendev->otherend) == 0 ||
  	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
  		xenbus_dev_fatal(xendev, -ENOENT,
  				 "unable to read other end from %s.  "
  				 "missing or inaccessible.",
  				 xendev->nodename);
  		free_otherend_details(xendev);
  		return -ENOENT;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
  
  void xenbus_otherend_changed(struct xenbus_watch *watch,
  			     const char **vec, unsigned int len,
  			     int ignore_on_shutdown)
  {
  	struct xenbus_device *dev =
  		container_of(watch, struct xenbus_device, otherend_watch);
  	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
  	enum xenbus_state state;
  
  	/* Protect us against watches firing on old details when the otherend
  	   details change, say immediately after a resume. */
  	if (!dev->otherend ||
  	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
  		    strlen(dev->otherend))) {
  		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
  			vec[XS_WATCH_PATH]);
  		return;
  	}
  
  	state = xenbus_read_driver_state(dev->otherend);
  
  	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
  		state, xenbus_strstate(state), dev->otherend_watch.node,
  		vec[XS_WATCH_PATH]);
  
  	/*
  	 * Ignore xenbus transitions during shutdown. This prevents us doing
  	 * work that can fail e.g., when the rootfs is gone.
  	 */
  	if (system_state > SYSTEM_RUNNING) {
  		if (ignore_on_shutdown && (state == XenbusStateClosing))
  			xenbus_frontend_closed(dev);
  		return;
  	}
  
  	if (drv->otherend_changed)
  		drv->otherend_changed(dev, state);
  }
  EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
  
  int xenbus_dev_probe(struct device *_dev)
  {
  	struct xenbus_device *dev = to_xenbus_device(_dev);
  	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
  	const struct xenbus_device_id *id;
  	int err;
  
  	DPRINTK("%s", dev->nodename);
  
  	if (!drv->probe) {
  		err = -ENODEV;
  		goto fail;
  	}
  
  	id = match_device(drv->ids, dev);
  	if (!id) {
  		err = -ENODEV;
  		goto fail;
  	}
  
  	err = talk_to_otherend(dev);
  	if (err) {
  		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
  			 dev->nodename);
  		return err;
  	}
  
  	err = drv->probe(dev, id);
  	if (err)
  		goto fail;
  
  	err = watch_otherend(dev);
  	if (err) {
  		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
  		       dev->nodename);
  		return err;
  	}
  
  	return 0;
  fail:
  	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
  	xenbus_switch_state(dev, XenbusStateClosed);
  	return err;
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_probe);
  
  int xenbus_dev_remove(struct device *_dev)
  {
  	struct xenbus_device *dev = to_xenbus_device(_dev);
  	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
  
  	DPRINTK("%s", dev->nodename);
  
  	free_otherend_watch(dev);
  
  	if (drv->remove)
  		drv->remove(dev);
  
  	free_otherend_details(dev);
  
  	xenbus_switch_state(dev, XenbusStateClosed);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_remove);
  
  void xenbus_dev_shutdown(struct device *_dev)
  {
  	struct xenbus_device *dev = to_xenbus_device(_dev);
  	unsigned long timeout = 5*HZ;
  
  	DPRINTK("%s", dev->nodename);
  
  	get_device(&dev->dev);
  	if (dev->state != XenbusStateConnected) {
  		printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
  		       dev->nodename, xenbus_strstate(dev->state));
  		goto out;
  	}
  	xenbus_switch_state(dev, XenbusStateClosing);
  	timeout = wait_for_completion_timeout(&dev->down, timeout);
  	if (!timeout)
  		printk(KERN_INFO "%s: %s timeout closing device\n",
  		       __func__, dev->nodename);
   out:
  	put_device(&dev->dev);
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
  
  int xenbus_register_driver_common(struct xenbus_driver *drv,
  				  struct xen_bus_type *bus)
  {
  	drv->driver.bus = &bus->bus;
  
  	return driver_register(&drv->driver);
  }
  EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
  
  void xenbus_unregister_driver(struct xenbus_driver *drv)
  {
  	driver_unregister(&drv->driver);
  }
  EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
  
  struct xb_find_info {
  	struct xenbus_device *dev;
  	const char *nodename;
  };
  
  static int cmp_dev(struct device *dev, void *data)
  {
  	struct xenbus_device *xendev = to_xenbus_device(dev);
  	struct xb_find_info *info = data;
  
  	if (!strcmp(xendev->nodename, info->nodename)) {
  		info->dev = xendev;
  		get_device(dev);
  		return 1;
  	}
  	return 0;
  }
  
  struct xenbus_device *xenbus_device_find(const char *nodename,
  					 struct bus_type *bus)
  {
  	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
  
  	bus_for_each_dev(bus, NULL, &info, cmp_dev);
  	return info.dev;
  }
  
  static int cleanup_dev(struct device *dev, void *data)
  {
  	struct xenbus_device *xendev = to_xenbus_device(dev);
  	struct xb_find_info *info = data;
  	int len = strlen(info->nodename);
  
  	DPRINTK("%s", info->nodename);
  
  	/* Match the info->nodename path, or any subdirectory of that path. */
  	if (strncmp(xendev->nodename, info->nodename, len))
  		return 0;
  
  	/* If the node name is longer, ensure it really is a subdirectory. */
  	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
  		return 0;
  
  	info->dev = xendev;
  	get_device(dev);
  	return 1;
  }
  
  static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
  {
  	struct xb_find_info info = { .nodename = path };
  
  	do {
  		info.dev = NULL;
  		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
  		if (info.dev) {
  			device_unregister(&info.dev->dev);
  			put_device(&info.dev->dev);
  		}
  	} while (info.dev);
  }
  
  static void xenbus_dev_release(struct device *dev)
  {
  	if (dev)
  		kfree(to_xenbus_device(dev));
  }
  
  static ssize_t nodename_show(struct device *dev,
  			     struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
  }
  
  static ssize_t devtype_show(struct device *dev,
  			    struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
  }
  
  static ssize_t modalias_show(struct device *dev,
  			     struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%s:%s\n", dev->bus->name,
  		       to_xenbus_device(dev)->devicetype);
  }
  
  struct device_attribute xenbus_dev_attrs[] = {
  	__ATTR_RO(nodename),
  	__ATTR_RO(devtype),
  	__ATTR_RO(modalias),
  	__ATTR_NULL
  };
  EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
  
  int xenbus_probe_node(struct xen_bus_type *bus,
  		      const char *type,
  		      const char *nodename)
  {
  	char devname[XEN_BUS_ID_SIZE];
  	int err;
  	struct xenbus_device *xendev;
  	size_t stringlen;
  	char *tmpstring;
  
  	enum xenbus_state state = xenbus_read_driver_state(nodename);
  
  	if (state != XenbusStateInitialising) {
  		/* Device is not new, so ignore it.  This can happen if a
  		   device is going away after switching to Closed.  */
  		return 0;
  	}
  
  	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
  	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
  	if (!xendev)
  		return -ENOMEM;
  
  	xendev->state = XenbusStateInitialising;
  
  	/* Copy the strings into the extra space. */
  
  	tmpstring = (char *)(xendev + 1);
  	strcpy(tmpstring, nodename);
  	xendev->nodename = tmpstring;
  
  	tmpstring += strlen(tmpstring) + 1;
  	strcpy(tmpstring, type);
  	xendev->devicetype = tmpstring;
  	init_completion(&xendev->down);
  
  	xendev->dev.bus = &bus->bus;
  	xendev->dev.release = xenbus_dev_release;
  
  	err = bus->get_bus_id(devname, xendev->nodename);
  	if (err)
  		goto fail;
  
  	dev_set_name(&xendev->dev, devname);
  
  	/* Register with generic device framework. */
  	err = device_register(&xendev->dev);
  	if (err)
  		goto fail;
  
  	return 0;
  fail:
  	kfree(xendev);
  	return err;
  }
  EXPORT_SYMBOL_GPL(xenbus_probe_node);
  
  static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
  {
  	int err = 0;
  	char **dir;
  	unsigned int dir_n = 0;
  	int i;
  
  	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
  	if (IS_ERR(dir))
  		return PTR_ERR(dir);
  
  	for (i = 0; i < dir_n; i++) {
  		err = bus->probe(bus, type, dir[i]);
  		if (err)
  			break;
  	}
  
  	kfree(dir);
  	return err;
  }
  
  int xenbus_probe_devices(struct xen_bus_type *bus)
  {
  	int err = 0;
  	char **dir;
  	unsigned int i, dir_n;
  
  	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
  	if (IS_ERR(dir))
  		return PTR_ERR(dir);
  
  	for (i = 0; i < dir_n; i++) {
  		err = xenbus_probe_device_type(bus, dir[i]);
  		if (err)
  			break;
  	}
  
  	kfree(dir);
  	return err;
  }
  EXPORT_SYMBOL_GPL(xenbus_probe_devices);
  
  static unsigned int char_count(const char *str, char c)
  {
  	unsigned int i, ret = 0;
  
  	for (i = 0; str[i]; i++)
  		if (str[i] == c)
  			ret++;
  	return ret;
  }
  
  static int strsep_len(const char *str, char c, unsigned int len)
  {
  	unsigned int i;
  
  	for (i = 0; str[i]; i++)
  		if (str[i] == c) {
  			if (len == 0)
  				return i;
  			len--;
  		}
  	return (len == 0) ? i : -ERANGE;
  }
  
  void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
  {
  	int exists, rootlen;
  	struct xenbus_device *dev;
  	char type[XEN_BUS_ID_SIZE];
  	const char *p, *root;
  
  	if (char_count(node, '/') < 2)
  		return;
  
  	exists = xenbus_exists(XBT_NIL, node, "");
  	if (!exists) {
  		xenbus_cleanup_devices(node, &bus->bus);
  		return;
  	}
  
  	/* backend/<type>/... or device/<type>/... */
  	p = strchr(node, '/') + 1;
  	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
  	type[XEN_BUS_ID_SIZE-1] = '\0';
  
  	rootlen = strsep_len(node, '/', bus->levels);
  	if (rootlen < 0)
  		return;
  	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
  	if (!root)
  		return;
  
  	dev = xenbus_device_find(root, &bus->bus);
  	if (!dev)
  		xenbus_probe_node(bus, type, root);
  	else
  		put_device(&dev->dev);
  
  	kfree(root);
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_changed);
  
  int xenbus_dev_suspend(struct device *dev)
  {
  	int err = 0;
  	struct xenbus_driver *drv;
  	struct xenbus_device *xdev
  		= container_of(dev, struct xenbus_device, dev);
  
  	DPRINTK("%s", xdev->nodename);
  
  	if (dev->driver == NULL)
  		return 0;
  	drv = to_xenbus_driver(dev->driver);
  	if (drv->suspend)
  		err = drv->suspend(xdev);
  	if (err)
  		printk(KERN_WARNING
  		       "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
  
  int xenbus_dev_resume(struct device *dev)
  {
  	int err;
  	struct xenbus_driver *drv;
  	struct xenbus_device *xdev
  		= container_of(dev, struct xenbus_device, dev);
  
  	DPRINTK("%s", xdev->nodename);
  
  	if (dev->driver == NULL)
  		return 0;
  	drv = to_xenbus_driver(dev->driver);
  	err = talk_to_otherend(xdev);
  	if (err) {
  		printk(KERN_WARNING
  		       "xenbus: resume (talk_to_otherend) %s failed: %i\n",
  		       dev_name(dev), err);
  		return err;
  	}
  
  	xdev->state = XenbusStateInitialising;
  
  	if (drv->resume) {
  		err = drv->resume(xdev);
  		if (err) {
  			printk(KERN_WARNING
  			       "xenbus: resume %s failed: %i\n",
  			       dev_name(dev), err);
  			return err;
  		}
  	}
  
  	err = watch_otherend(xdev);
  	if (err) {
  		printk(KERN_WARNING
  		       "xenbus_probe: resume (watch_otherend) %s failed: "
  		       "%d.\n", dev_name(dev), err);
  		return err;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_resume);
  
  int xenbus_dev_cancel(struct device *dev)
  {
  	/* Do nothing */
  	DPRINTK("cancel");
  	return 0;
  }
  EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
  
  /* A flag to determine if xenstored is 'ready' (i.e. has started) */
  int xenstored_ready;
  
  
  int register_xenstore_notifier(struct notifier_block *nb)
  {
  	int ret = 0;
  
  	if (xenstored_ready > 0)
  		ret = nb->notifier_call(nb, 0, NULL);
  	else
  		blocking_notifier_chain_register(&xenstore_chain, nb);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(register_xenstore_notifier);
  
  void unregister_xenstore_notifier(struct notifier_block *nb)
  {
  	blocking_notifier_chain_unregister(&xenstore_chain, nb);
  }
  EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
  
  void xenbus_probe(struct work_struct *unused)
  {
  	xenstored_ready = 1;
  
  	/* Notify others that xenstore is up */
  	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
  }
  EXPORT_SYMBOL_GPL(xenbus_probe);
  
  static int __init xenbus_probe_initcall(void)
  {
  	if (!xen_domain())
  		return -ENODEV;
  
  	if (xen_initial_domain() || xen_hvm_domain())
  		return 0;
  
  	xenbus_probe(NULL);
  	return 0;
  }
  
  device_initcall(xenbus_probe_initcall);
  
  /* Set up event channel for xenstored which is run as a local process
   * (this is normally used only in dom0)
   */
  static int __init xenstored_local_init(void)
  {
  	int err = 0;
  	unsigned long page = 0;
  	struct evtchn_alloc_unbound alloc_unbound;
  
  	/* Allocate Xenstore page */
  	page = get_zeroed_page(GFP_KERNEL);
  	if (!page)
  		goto out_err;
  
  	xen_store_mfn = xen_start_info->store_mfn =
  		pfn_to_mfn(virt_to_phys((void *)page) >>
  			   PAGE_SHIFT);
  
  	/* Next allocate a local port which xenstored can bind to */
  	alloc_unbound.dom        = DOMID_SELF;
  	alloc_unbound.remote_dom = DOMID_SELF;
  
  	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
  					  &alloc_unbound);
  	if (err == -ENOSYS)
  		goto out_err;
  
  	BUG_ON(err);
  	xen_store_evtchn = xen_start_info->store_evtchn =
  		alloc_unbound.port;
  
  	return 0;
  
   out_err:
  	if (page != 0)
  		free_page(page);
  	return err;
  }
  
  static int __init xenbus_init(void)
  {
  	int err = 0;
  
  	if (!xen_domain())
  		return -ENODEV;
  
  	xenbus_ring_ops_init();
  
  	if (xen_hvm_domain()) {
  		uint64_t v = 0;
  		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
  		if (err)
  			goto out_error;
  		xen_store_evtchn = (int)v;
  		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
  		if (err)
  			goto out_error;
  		xen_store_mfn = (unsigned long)v;
  		xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
  	} else {
  		xen_store_evtchn = xen_start_info->store_evtchn;
  		xen_store_mfn = xen_start_info->store_mfn;
  		if (xen_store_evtchn)
  			xenstored_ready = 1;
  		else {
  			err = xenstored_local_init();
  			if (err)
  				goto out_error;
  		}
  		xen_store_interface = mfn_to_virt(xen_store_mfn);
  	}
  
  	/* Initialize the interface to xenstore. */
  	err = xs_init();
  	if (err) {
  		printk(KERN_WARNING
  		       "XENBUS: Error initializing xenstore comms: %i\n", err);
  		goto out_error;
  	}
  
  #ifdef CONFIG_XEN_COMPAT_XENFS
  	/*
  	 * Create xenfs mountpoint in /proc for compatibility with
  	 * utilities that expect to find "xenbus" under "/proc/xen".
  	 */
  	proc_mkdir("xen", NULL);
  #endif
  
  out_error:
  	return err;
  }
  
  postcore_initcall(xenbus_init);
  
  MODULE_LICENSE("GPL");
  