arch/sparc64/kernel/vio.c - maze/linux - Git at Google

 /* vio.c: Virtual I/O channel devices probing infrastructure.
  *
  *    Copyright (c) 2003-2005 IBM Corp.
  *     Dave Engebretsen engebret@us.ibm.com
  *     Santiago Leon santil@us.ibm.com
  *     Hollis Blanchard <hollisb@us.ibm.com>
  *     Stephen Rothwell
  *
  * Adapted to sparc64 by David S. Miller davem@davemloft.net
  */

 #include <linux/kernel.h>
 #include <linux/irq.h>
 #include <linux/init.h>

 #include <asm/mdesc.h>
 #include <asm/vio.h>

 static const struct vio_device_id *vio_match_device(
 	const struct vio_device_id *matches,
 	const struct vio_dev *dev)
 {
 	const char *type, *compat;
 	int len;

 	type = dev->type;
 	compat = dev->compat;
 	len = dev->compat_len;

 	while (matches->type[0] || matches->compat[0]) {
 		int match = 1;
 		if (matches->type[0])
 			match &= !strcmp(matches->type, type);

 		if (matches->compat[0]) {
 			match &= len &&
 				of_find_in_proplist(compat, matches->compat, len);
 		}
 		if (match)
 			return matches;
 		matches++;
 	}
 	return NULL;
 }

 static int vio_bus_match(struct device *dev, struct device_driver *drv)
 {
 	struct vio_dev *vio_dev = to_vio_dev(dev);
 	struct vio_driver *vio_drv = to_vio_driver(drv);
 	const struct vio_device_id *matches = vio_drv->id_table;

 	if (!matches)
 		return 0;

 	return vio_match_device(matches, vio_dev) != NULL;
 }

 static int vio_device_probe(struct device *dev)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
 	struct vio_driver *drv = to_vio_driver(dev->driver);
 	const struct vio_device_id *id;
 	int error = -ENODEV;

 	if (drv->probe) {
 		id = vio_match_device(drv->id_table, vdev);
 		if (id)
 			error = drv->probe(vdev, id);
 	}

 	return error;
 }

 static int vio_device_remove(struct device *dev)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
 	struct vio_driver *drv = to_vio_driver(dev->driver);

 	if (drv->remove)
 		return drv->remove(vdev);

 	return 1;
 }

 static ssize_t devspec_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
 	const char *str = "none";

 	if (!strcmp(vdev->type, "vnet-port"))
 		str = "vnet";
 	else if (!strcmp(vdev->type, "vdc-port"))
 		str = "vdisk";

 	return sprintf(buf, "%s\n", str);
 }

 static ssize_t type_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);
 	return sprintf(buf, "%s\n", vdev->type);
 }

 static struct device_attribute vio_dev_attrs[] = {
 	__ATTR_RO(devspec),
 	__ATTR_RO(type),
 	__ATTR_NULL
 };

 static struct bus_type vio_bus_type = {
 	.name		= "vio",
 	.dev_attrs	= vio_dev_attrs,
 	.match		= vio_bus_match,
 	.probe		= vio_device_probe,
 	.remove		= vio_device_remove,
 };

 int vio_register_driver(struct vio_driver *viodrv)
 {
 	viodrv->driver.bus = &vio_bus_type;

 	return driver_register(&viodrv->driver);
 }
 EXPORT_SYMBOL(vio_register_driver);

 void vio_unregister_driver(struct vio_driver *viodrv)
 {
 	driver_unregister(&viodrv->driver);
 }
 EXPORT_SYMBOL(vio_unregister_driver);

 static void vio_dev_release(struct device *dev)
 {
 	kfree(to_vio_dev(dev));
 }

 static ssize_t
 show_pciobppath_attr(struct device *dev, struct device_attribute *attr,
 		     char *buf)
 {
 	struct vio_dev *vdev;
 	struct device_node *dp;

 	vdev = to_vio_dev(dev);
 	dp = vdev->dp;

 	return snprintf (buf, PAGE_SIZE, "%s\n", dp->full_name);
 }

 static DEVICE_ATTR(obppath, S_IRUSR | S_IRGRP | S_IROTH,
 		   show_pciobppath_attr, NULL);

 struct device_node *cdev_node;

 static struct vio_dev *root_vdev;
 static u64 cdev_cfg_handle;

 static void vio_fill_channel_info(struct mdesc_handle *hp, u64 mp,
 				  struct vio_dev *vdev)
 {
 	u64 a;

 	mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_FWD) {
 		const u64 *chan_id;
 		const u64 *irq;
 		u64 target;

 		target = mdesc_arc_target(hp, a);

 		irq = mdesc_get_property(hp, target, "tx-ino", NULL);
 		if (irq)
 			vdev->tx_irq = sun4v_build_virq(cdev_cfg_handle, *irq);

 		irq = mdesc_get_property(hp, target, "rx-ino", NULL);
 		if (irq)
 			vdev->rx_irq = sun4v_build_virq(cdev_cfg_handle, *irq);

 		chan_id = mdesc_get_property(hp, target, "id", NULL);
 		if (chan_id)
 			vdev->channel_id = *chan_id;
 	}
 }

 static struct vio_dev *vio_create_one(struct mdesc_handle *hp, u64 mp,
 				      struct device *parent)
 {
 	const char *type, *compat, *bus_id_name;
 	struct device_node *dp;
 	struct vio_dev *vdev;
 	int err, tlen, clen;
 	const u64 *id, *cfg_handle;
 	u64 a;

 	type = mdesc_get_property(hp, mp, "device-type", &tlen);
 	if (!type) {
 		type = mdesc_get_property(hp, mp, "name", &tlen);
 		if (!type) {
 			type = mdesc_node_name(hp, mp);
 			tlen = strlen(type) + 1;
 		}
 	}
 	if (tlen > VIO_MAX_TYPE_LEN) {
 		printk(KERN_ERR "VIO: Type string [%s] is too long.\n",
 		       type);
 		return NULL;
 	}

 	id = mdesc_get_property(hp, mp, "id", NULL);

 	cfg_handle = NULL;
 	mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_BACK) {
 		u64 target;

 		target = mdesc_arc_target(hp, a);
 		cfg_handle = mdesc_get_property(hp, target,
 						"cfg-handle", NULL);
 		if (cfg_handle)
 			break;
 	}

 	bus_id_name = type;
 	if (!strcmp(type, "domain-services-port"))
 		bus_id_name = "ds";

 	if (strlen(bus_id_name) >= KOBJ_NAME_LEN - 4) {
 		printk(KERN_ERR "VIO: bus_id_name [%s] is too long.\n",
 		       bus_id_name);
 		return NULL;
 	}

 	compat = mdesc_get_property(hp, mp, "device-type", &clen);
 	if (!compat) {
 		clen = 0;
 	} else if (clen > VIO_MAX_COMPAT_LEN) {
 		printk(KERN_ERR "VIO: Compat len %d for [%s] is too long.\n",
 		       clen, type);
 		return NULL;
 	}

 	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
 	if (!vdev) {
 		printk(KERN_ERR "VIO: Could not allocate vio_dev\n");
 		return NULL;
 	}

 	vdev->mp = mp;
 	memcpy(vdev->type, type, tlen);
 	if (compat)
 		memcpy(vdev->compat, compat, clen);
 	else
 		memset(vdev->compat, 0, sizeof(vdev->compat));
 	vdev->compat_len = clen;

 	vdev->channel_id = ~0UL;
 	vdev->tx_irq = ~0;
 	vdev->rx_irq = ~0;

 	vio_fill_channel_info(hp, mp, vdev);

 	if (!id) {
 		snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s",
 			 bus_id_name);
 		vdev->dev_no = ~(u64)0;
 	} else if (!cfg_handle) {
 		snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s-%lu",
 			 bus_id_name, *id);
 		vdev->dev_no = *id;
 	} else {
 		snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s-%lu-%lu",
 			 bus_id_name, *cfg_handle, *id);
 		vdev->dev_no = *cfg_handle;
 	}

 	vdev->dev.parent = parent;
 	vdev->dev.bus = &vio_bus_type;
 	vdev->dev.release = vio_dev_release;

 	if (parent == NULL) {
 		dp = cdev_node;
 	} else if (to_vio_dev(parent) == root_vdev) {
 		dp = of_get_next_child(cdev_node, NULL);
 		while (dp) {
 			if (!strcmp(dp->type, type))
 				break;

 			dp = of_get_next_child(cdev_node, dp);
 		}
 	} else {
 		dp = to_vio_dev(parent)->dp;
 	}
 	vdev->dp = dp;

 	printk(KERN_INFO "VIO: Adding device %s\n", vdev->dev.bus_id);

 	err = device_register(&vdev->dev);
 	if (err) {
 		printk(KERN_ERR "VIO: Could not register device %s, err=%d\n",
 		       vdev->dev.bus_id, err);
 		kfree(vdev);
 		return NULL;
 	}
 	if (vdev->dp)
 		err = sysfs_create_file(&vdev->dev.kobj,
 					&dev_attr_obppath.attr);

 	return vdev;
 }

 static void vio_add(struct mdesc_handle *hp, u64 node)
 {
 	(void) vio_create_one(hp, node, &root_vdev->dev);
 }

 static int vio_md_node_match(struct device *dev, void *arg)
 {
 	struct vio_dev *vdev = to_vio_dev(dev);

 	if (vdev->mp == (u64) arg)
 		return 1;

 	return 0;
 }

 static void vio_remove(struct mdesc_handle *hp, u64 node)
 {
 	struct device *dev;

 	dev = device_find_child(&root_vdev->dev, (void *) node,
 				vio_md_node_match);
 	if (dev) {
 		printk(KERN_INFO "VIO: Removing device %s\n", dev->bus_id);

 		device_unregister(dev);
 	}
 }

 static struct mdesc_notifier_client vio_device_notifier = {
 	.add		= vio_add,
 	.remove		= vio_remove,
 	.node_name	= "virtual-device-port",
 };

 /* We are only interested in domain service ports under the
  * "domain-services" node.  On control nodes there is another port
  * under "openboot" that we should not mess with as aparently that is
  * reserved exclusively for OBP use.
  */
 static void vio_add_ds(struct mdesc_handle *hp, u64 node)
 {
 	int found;
 	u64 a;

 	found = 0;
 	mdesc_for_each_arc(a, hp, node, MDESC_ARC_TYPE_BACK) {
 		u64 target = mdesc_arc_target(hp, a);
 		const char *name = mdesc_node_name(hp, target);

 		if (!strcmp(name, "domain-services")) {
 			found = 1;
 			break;
 		}
 	}

 	if (found)
 		(void) vio_create_one(hp, node, &root_vdev->dev);
 }

 static struct mdesc_notifier_client vio_ds_notifier = {
 	.add		= vio_add_ds,
 	.remove		= vio_remove,
 	.node_name	= "domain-services-port",
 };

 const char *channel_devices_node = "channel-devices";
 const char *channel_devices_compat = "SUNW,sun4v-channel-devices";
 const char *cfg_handle_prop = "cfg-handle";

 static int __init vio_init(void)
 {
 	struct mdesc_handle *hp;
 	const char *compat;
 	const u64 *cfg_handle;
 	int err, len;
 	u64 root;

 	err = bus_register(&vio_bus_type);
 	if (err) {
 		printk(KERN_ERR "VIO: Could not register bus type err=%d\n",
 		       err);
 		return err;
 	}

 	hp = mdesc_grab();
 	if (!hp)
 		return 0;

 	root = mdesc_node_by_name(hp, MDESC_NODE_NULL, channel_devices_node);
 	if (root == MDESC_NODE_NULL) {
 		printk(KERN_INFO "VIO: No channel-devices MDESC node.\n");
 		mdesc_release(hp);
 		return 0;
 	}

 	cdev_node = of_find_node_by_name(NULL, "channel-devices");
 	err = -ENODEV;
 	if (!cdev_node) {
 		printk(KERN_INFO "VIO: No channel-devices OBP node.\n");
 		goto out_release;
 	}

 	compat = mdesc_get_property(hp, root, "compatible", &len);
 	if (!compat) {
 		printk(KERN_ERR "VIO: Channel devices lacks compatible "
 		       "property\n");
 		goto out_release;
 	}
 	if (!of_find_in_proplist(compat, channel_devices_compat, len)) {
 		printk(KERN_ERR "VIO: Channel devices node lacks (%s) "
 		       "compat entry.\n", channel_devices_compat);
 		goto out_release;
 	}

 	cfg_handle = mdesc_get_property(hp, root, cfg_handle_prop, NULL);
 	if (!cfg_handle) {
 		printk(KERN_ERR "VIO: Channel devices lacks %s property\n",
 		       cfg_handle_prop);
 		goto out_release;
 	}

 	cdev_cfg_handle = *cfg_handle;

 	root_vdev = vio_create_one(hp, root, NULL);
 	err = -ENODEV;
 	if (!root_vdev) {
 		printk(KERN_ERR "VIO: Coult not create root device.\n");
 		goto out_release;
 	}

 	mdesc_register_notifier(&vio_device_notifier);
 	mdesc_register_notifier(&vio_ds_notifier);

 	mdesc_release(hp);

 	return err;

 out_release:
 	mdesc_release(hp);
 	return err;
 }

 postcore_initcall(vio_init);
	/* vio.c: Virtual I/O channel devices probing infrastructure.
	*
	* Copyright (c) 2003-2005 IBM Corp.
	* Dave Engebretsen engebret@us.ibm.com
	* Santiago Leon santil@us.ibm.com
	* Hollis Blanchard <hollisb@us.ibm.com>
	* Stephen Rothwell
	*
	* Adapted to sparc64 by David S. Miller davem@davemloft.net
	*/

	#include <linux/kernel.h>
	#include <linux/irq.h>
	#include <linux/init.h>

	#include <asm/mdesc.h>
	#include <asm/vio.h>

	static const struct vio_device_id *vio_match_device(
	const struct vio_device_id *matches,
	const struct vio_dev *dev)
	{
	const char type, compat;
	int len;

	type = dev->type;
	compat = dev->compat;
	len = dev->compat_len;

	while (matches->type[0] \|\| matches->compat[0]) {
	int match = 1;
	if (matches->type[0])
	match &= !strcmp(matches->type, type);

	if (matches->compat[0]) {
	match &= len &&
	of_find_in_proplist(compat, matches->compat, len);
	}
	if (match)
	return matches;
	matches++;
	}
	return NULL;
	}

	static int vio_bus_match(struct device dev, struct device_driver drv)
	{
	struct vio_dev *vio_dev = to_vio_dev(dev);
	struct vio_driver *vio_drv = to_vio_driver(drv);
	const struct vio_device_id *matches = vio_drv->id_table;

	if (!matches)
	return 0;

	return vio_match_device(matches, vio_dev) != NULL;
	}

	static int vio_device_probe(struct device *dev)
	{
	struct vio_dev *vdev = to_vio_dev(dev);
	struct vio_driver *drv = to_vio_driver(dev->driver);
	const struct vio_device_id *id;
	int error = -ENODEV;

	if (drv->probe) {
	id = vio_match_device(drv->id_table, vdev);
	if (id)
	error = drv->probe(vdev, id);
	}

	return error;
	}

	static int vio_device_remove(struct device *dev)
	{
	struct vio_dev *vdev = to_vio_dev(dev);
	struct vio_driver *drv = to_vio_driver(dev->driver);

	if (drv->remove)
	return drv->remove(vdev);

	return 1;
	}

	static ssize_t devspec_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct vio_dev *vdev = to_vio_dev(dev);
	const char *str = "none";

	if (!strcmp(vdev->type, "vnet-port"))
	str = "vnet";
	else if (!strcmp(vdev->type, "vdc-port"))
	str = "vdisk";

	return sprintf(buf, "%s\n", str);
	}

	static ssize_t type_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct vio_dev *vdev = to_vio_dev(dev);
	return sprintf(buf, "%s\n", vdev->type);
	}

	static struct device_attribute vio_dev_attrs[] = {
	__ATTR_RO(devspec),
	__ATTR_RO(type),
	__ATTR_NULL
	};

	static struct bus_type vio_bus_type = {
	.name = "vio",
	.dev_attrs = vio_dev_attrs,
	.match = vio_bus_match,
	.probe = vio_device_probe,
	.remove = vio_device_remove,
	};

	int vio_register_driver(struct vio_driver *viodrv)
	{
	viodrv->driver.bus = &vio_bus_type;

	return driver_register(&viodrv->driver);
	}
	EXPORT_SYMBOL(vio_register_driver);

	void vio_unregister_driver(struct vio_driver *viodrv)
	{
	driver_unregister(&viodrv->driver);
	}
	EXPORT_SYMBOL(vio_unregister_driver);

	static void vio_dev_release(struct device *dev)
	{
	kfree(to_vio_dev(dev));
	}

	static ssize_t
	show_pciobppath_attr(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct vio_dev *vdev;
	struct device_node *dp;

	vdev = to_vio_dev(dev);
	dp = vdev->dp;

	return snprintf (buf, PAGE_SIZE, "%s\n", dp->full_name);
	}

	static DEVICE_ATTR(obppath, S_IRUSR \| S_IRGRP \| S_IROTH,
	show_pciobppath_attr, NULL);

	struct device_node *cdev_node;

	static struct vio_dev *root_vdev;
	static u64 cdev_cfg_handle;

	static void vio_fill_channel_info(struct mdesc_handle *hp, u64 mp,
	struct vio_dev *vdev)
	{
	u64 a;

	mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_FWD) {
	const u64 *chan_id;
	const u64 *irq;
	u64 target;

	target = mdesc_arc_target(hp, a);

	irq = mdesc_get_property(hp, target, "tx-ino", NULL);
	if (irq)
	vdev->tx_irq = sun4v_build_virq(cdev_cfg_handle, *irq);

	irq = mdesc_get_property(hp, target, "rx-ino", NULL);
	if (irq)
	vdev->rx_irq = sun4v_build_virq(cdev_cfg_handle, *irq);

	chan_id = mdesc_get_property(hp, target, "id", NULL);
	if (chan_id)
	vdev->channel_id = *chan_id;
	}
	}

	static struct vio_dev vio_create_one(struct mdesc_handle hp, u64 mp,
	struct device *parent)
	{
	const char type, compat, *bus_id_name;
	struct device_node *dp;
	struct vio_dev *vdev;
	int err, tlen, clen;
	const u64 id, cfg_handle;
	u64 a;

	type = mdesc_get_property(hp, mp, "device-type", &tlen);
	if (!type) {
	type = mdesc_get_property(hp, mp, "name", &tlen);
	if (!type) {
	type = mdesc_node_name(hp, mp);
	tlen = strlen(type) + 1;
	}
	}
	if (tlen > VIO_MAX_TYPE_LEN) {
	printk(KERN_ERR "VIO: Type string [%s] is too long.\n",
	type);
	return NULL;
	}

	id = mdesc_get_property(hp, mp, "id", NULL);

	cfg_handle = NULL;
	mdesc_for_each_arc(a, hp, mp, MDESC_ARC_TYPE_BACK) {
	u64 target;

	target = mdesc_arc_target(hp, a);
	cfg_handle = mdesc_get_property(hp, target,
	"cfg-handle", NULL);
	if (cfg_handle)
	break;
	}

	bus_id_name = type;
	if (!strcmp(type, "domain-services-port"))
	bus_id_name = "ds";

	if (strlen(bus_id_name) >= KOBJ_NAME_LEN - 4) {
	printk(KERN_ERR "VIO: bus_id_name [%s] is too long.\n",
	bus_id_name);
	return NULL;
	}

	compat = mdesc_get_property(hp, mp, "device-type", &clen);
	if (!compat) {
	clen = 0;
	} else if (clen > VIO_MAX_COMPAT_LEN) {
	printk(KERN_ERR "VIO: Compat len %d for [%s] is too long.\n",
	clen, type);
	return NULL;
	}

	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
	if (!vdev) {
	printk(KERN_ERR "VIO: Could not allocate vio_dev\n");
	return NULL;
	}

	vdev->mp = mp;
	memcpy(vdev->type, type, tlen);
	if (compat)
	memcpy(vdev->compat, compat, clen);
	else
	memset(vdev->compat, 0, sizeof(vdev->compat));
	vdev->compat_len = clen;

	vdev->channel_id = ~0UL;
	vdev->tx_irq = ~0;
	vdev->rx_irq = ~0;

	vio_fill_channel_info(hp, mp, vdev);

	if (!id) {
	snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s",
	bus_id_name);
	vdev->dev_no = ~(u64)0;
	} else if (!cfg_handle) {
	snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s-%lu",
	bus_id_name, *id);
	vdev->dev_no = *id;
	} else {
	snprintf(vdev->dev.bus_id, BUS_ID_SIZE, "%s-%lu-%lu",
	bus_id_name, cfg_handle, id);
	vdev->dev_no = *cfg_handle;
	}

	vdev->dev.parent = parent;
	vdev->dev.bus = &vio_bus_type;
	vdev->dev.release = vio_dev_release;

	if (parent == NULL) {
	dp = cdev_node;
	} else if (to_vio_dev(parent) == root_vdev) {
	dp = of_get_next_child(cdev_node, NULL);
	while (dp) {
	if (!strcmp(dp->type, type))
	break;

	dp = of_get_next_child(cdev_node, dp);
	}
	} else {
	dp = to_vio_dev(parent)->dp;
	}
	vdev->dp = dp;

	printk(KERN_INFO "VIO: Adding device %s\n", vdev->dev.bus_id);

	err = device_register(&vdev->dev);
	if (err) {
	printk(KERN_ERR "VIO: Could not register device %s, err=%d\n",
	vdev->dev.bus_id, err);
	kfree(vdev);
	return NULL;
	}
	if (vdev->dp)
	err = sysfs_create_file(&vdev->dev.kobj,
	&dev_attr_obppath.attr);

	return vdev;
	}

	static void vio_add(struct mdesc_handle *hp, u64 node)
	{
	(void) vio_create_one(hp, node, &root_vdev->dev);
	}

	static int vio_md_node_match(struct device dev, void arg)
	{
	struct vio_dev *vdev = to_vio_dev(dev);

	if (vdev->mp == (u64) arg)
	return 1;

	return 0;
	}

	static void vio_remove(struct mdesc_handle *hp, u64 node)
	{
	struct device *dev;

	dev = device_find_child(&root_vdev->dev, (void *) node,
	vio_md_node_match);
	if (dev) {
	printk(KERN_INFO "VIO: Removing device %s\n", dev->bus_id);

	device_unregister(dev);
	}
	}

	static struct mdesc_notifier_client vio_device_notifier = {
	.add = vio_add,
	.remove = vio_remove,
	.node_name = "virtual-device-port",
	};

	/* We are only interested in domain service ports under the
	* "domain-services" node. On control nodes there is another port
	* under "openboot" that we should not mess with as aparently that is
	* reserved exclusively for OBP use.
	*/
	static void vio_add_ds(struct mdesc_handle *hp, u64 node)
	{
	int found;
	u64 a;

	found = 0;
	mdesc_for_each_arc(a, hp, node, MDESC_ARC_TYPE_BACK) {
	u64 target = mdesc_arc_target(hp, a);
	const char *name = mdesc_node_name(hp, target);

	if (!strcmp(name, "domain-services")) {
	found = 1;
	break;
	}
	}

	if (found)
	(void) vio_create_one(hp, node, &root_vdev->dev);
	}

	static struct mdesc_notifier_client vio_ds_notifier = {
	.add = vio_add_ds,
	.remove = vio_remove,
	.node_name = "domain-services-port",
	};

	const char *channel_devices_node = "channel-devices";
	const char *channel_devices_compat = "SUNW,sun4v-channel-devices";
	const char *cfg_handle_prop = "cfg-handle";

	static int __init vio_init(void)
	{
	struct mdesc_handle *hp;
	const char *compat;
	const u64 *cfg_handle;
	int err, len;
	u64 root;

	err = bus_register(&vio_bus_type);
	if (err) {
	printk(KERN_ERR "VIO: Could not register bus type err=%d\n",
	err);
	return err;
	}

	hp = mdesc_grab();
	if (!hp)
	return 0;

	root = mdesc_node_by_name(hp, MDESC_NODE_NULL, channel_devices_node);
	if (root == MDESC_NODE_NULL) {
	printk(KERN_INFO "VIO: No channel-devices MDESC node.\n");
	mdesc_release(hp);
	return 0;
	}

	cdev_node = of_find_node_by_name(NULL, "channel-devices");
	err = -ENODEV;
	if (!cdev_node) {
	printk(KERN_INFO "VIO: No channel-devices OBP node.\n");
	goto out_release;
	}

	compat = mdesc_get_property(hp, root, "compatible", &len);
	if (!compat) {
	printk(KERN_ERR "VIO: Channel devices lacks compatible "
	"property\n");
	goto out_release;
	}
	if (!of_find_in_proplist(compat, channel_devices_compat, len)) {
	printk(KERN_ERR "VIO: Channel devices node lacks (%s) "
	"compat entry.\n", channel_devices_compat);
	goto out_release;
	}

	cfg_handle = mdesc_get_property(hp, root, cfg_handle_prop, NULL);
	if (!cfg_handle) {
	printk(KERN_ERR "VIO: Channel devices lacks %s property\n",
	cfg_handle_prop);
	goto out_release;
	}

	cdev_cfg_handle = *cfg_handle;

	root_vdev = vio_create_one(hp, root, NULL);
	err = -ENODEV;
	if (!root_vdev) {
	printk(KERN_ERR "VIO: Coult not create root device.\n");
	goto out_release;
	}

	mdesc_register_notifier(&vio_device_notifier);
	mdesc_register_notifier(&vio_ds_notifier);

	mdesc_release(hp);

	return err;

	out_release:
	mdesc_release(hp);
	return err;
	}

	postcore_initcall(vio_init);