1 files changed, 503 insertions, 0 deletions
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
new file mode 100644
index 0000000000000..2109cfe80219d
--- /dev/null
+++ b/drivers/dax/bus.c
@@ -0,0 +1,503 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
+#include <linux/memremap.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/dax.h>
+#include "dax-private.h"
+#include "bus.h"
+
+static struct class *dax_class;
+
+static DEFINE_MUTEX(dax_bus_lock);
+
+#define DAX_NAME_LEN 30
+struct dax_id {
+	struct list_head list;
+	char dev_name[DAX_NAME_LEN];
+};
+
+static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	/*
+	 * We only ever expect to handle device-dax instances, i.e. the
+	 * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
+	 */
+	return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
+}
+
+static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
+{
+	return container_of(drv, struct dax_device_driver, drv);
+}
+
+static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
+		const char *dev_name)
+{
+	struct dax_id *dax_id;
+
+	lockdep_assert_held(&dax_bus_lock);
+
+	list_for_each_entry(dax_id, &dax_drv->ids, list)
+		if (sysfs_streq(dax_id->dev_name, dev_name))
+			return dax_id;
+	return NULL;
+}
+
+static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
+{
+	int match;
+
+	mutex_lock(&dax_bus_lock);
+	match = !!__dax_match_id(dax_drv, dev_name(dev));
+	mutex_unlock(&dax_bus_lock);
+
+	return match;
+}
+
+enum id_action {
+	ID_REMOVE,
+	ID_ADD,
+};
+
+static ssize_t do_id_store(struct device_driver *drv, const char *buf,
+		size_t count, enum id_action action)
+{
+	struct dax_device_driver *dax_drv = to_dax_drv(drv);
+	unsigned int region_id, id;
+	char devname[DAX_NAME_LEN];
+	struct dax_id *dax_id;
+	ssize_t rc = count;
+	int fields;
+
+	fields = sscanf(buf, "dax%d.%d", &region_id, &id);
+	if (fields != 2)
+		return -EINVAL;
+	sprintf(devname, "dax%d.%d", region_id, id);
+	if (!sysfs_streq(buf, devname))
+		return -EINVAL;
+
+	mutex_lock(&dax_bus_lock);
+	dax_id = __dax_match_id(dax_drv, buf);
+	if (!dax_id) {
+		if (action == ID_ADD) {
+			dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
+			if (dax_id) {
+				strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
+				list_add(&dax_id->list, &dax_drv->ids);
+			} else
+				rc = -ENOMEM;
+		} else
+			/* nothing to remove */;
+	} else if (action == ID_REMOVE) {
+		list_del(&dax_id->list);
+		kfree(dax_id);
+	} else
+		/* dax_id already added */;
+	mutex_unlock(&dax_bus_lock);
+
+	if (rc < 0)
+		return rc;
+	if (action == ID_ADD)
+		rc = driver_attach(drv);
+	if (rc)
+		return rc;
+	return count;
+}
+
+static ssize_t new_id_store(struct device_driver *drv, const char *buf,
+		size_t count)
+{
+	return do_id_store(drv, buf, count, ID_ADD);
+}
+static DRIVER_ATTR_WO(new_id);
+
+static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
+		size_t count)
+{
+	return do_id_store(drv, buf, count, ID_REMOVE);
+}
+static DRIVER_ATTR_WO(remove_id);
+
+static struct attribute *dax_drv_attrs[] = {
+	&driver_attr_new_id.attr,
+	&driver_attr_remove_id.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(dax_drv);
+
+static int dax_bus_match(struct device *dev, struct device_driver *drv);
+
+static struct bus_type dax_bus_type = {
+	.name = "dax",
+	.uevent = dax_bus_uevent,
+	.match = dax_bus_match,
+	.drv_groups = dax_drv_groups,
+};
+
+static int dax_bus_match(struct device *dev, struct device_driver *drv)
+{
+	struct dax_device_driver *dax_drv = to_dax_drv(drv);
+
+	/*
+	 * All but the 'device-dax' driver, which has 'match_always'
+	 * set, requires an exact id match.
+	 */
+	if (dax_drv->match_always)
+		return 1;
+
+	return dax_match_id(dax_drv, dev);
+}
+
+/*
+ * Rely on the fact that drvdata is set before the attributes are
+ * registered, and that the attributes are unregistered before drvdata
+ * is cleared to assume that drvdata is always valid.
+ */
+static ssize_t id_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct dax_region *dax_region = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", dax_region->id);
+}
+static DEVICE_ATTR_RO(id);
+
+static ssize_t region_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct dax_region *dax_region = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%llu\n", (unsigned long long)
+			resource_size(&dax_region->res));
+}
+static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
+		region_size_show, NULL);
+
+static ssize_t align_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct dax_region *dax_region = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", dax_region->align);
+}
+static DEVICE_ATTR_RO(align);
+
+static struct attribute *dax_region_attributes[] = {
+	&dev_attr_region_size.attr,
+	&dev_attr_align.attr,
+	&dev_attr_id.attr,
+	NULL,
+};
+
+static const struct attribute_group dax_region_attribute_group = {
+	.name = "dax_region",
+	.attrs = dax_region_attributes,
+};
+
+static const struct attribute_group *dax_region_attribute_groups[] = {
+	&dax_region_attribute_group,
+	NULL,
+};
+
+static void dax_region_free(struct kref *kref)
+{
+	struct dax_region *dax_region;
+
+	dax_region = container_of(kref, struct dax_region, kref);
+	kfree(dax_region);
+}
+
+void dax_region_put(struct dax_region *dax_region)
+{
+	kref_put(&dax_region->kref, dax_region_free);
+}
+EXPORT_SYMBOL_GPL(dax_region_put);
+
+static void dax_region_unregister(void *region)
+{
+	struct dax_region *dax_region = region;
+
+	sysfs_remove_groups(&dax_region->dev->kobj,
+			dax_region_attribute_groups);
+	dax_region_put(dax_region);
+}
+
+struct dax_region *alloc_dax_region(struct device *parent, int region_id,
+		struct resource *res, int target_node, unsigned int align,
+		unsigned long pfn_flags)
+{
+	struct dax_region *dax_region;
+
+	/*
+	 * The DAX core assumes that it can store its private data in
+	 * parent->driver_data. This WARN is a reminder / safeguard for
+	 * developers of device-dax drivers.
+	 */
+	if (dev_get_drvdata(parent)) {
+		dev_WARN(parent, "dax core failed to setup private data\n");
+		return NULL;
+	}
+
+	if (!IS_ALIGNED(res->start, align)
+			|| !IS_ALIGNED(resource_size(res), align))
+		return NULL;
+
+	dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
+	if (!dax_region)
+		return NULL;
+
+	dev_set_drvdata(parent, dax_region);
+	memcpy(&dax_region->res, res, sizeof(*res));
+	dax_region->pfn_flags = pfn_flags;
+	kref_init(&dax_region->kref);
+	dax_region->id = region_id;
+	dax_region->align = align;
+	dax_region->dev = parent;
+	dax_region->target_node = target_node;
+	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
+		kfree(dax_region);
+		return NULL;
+	}
+
+	kref_get(&dax_region->kref);
+	if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
+		return NULL;
+	return dax_region;
+}
+EXPORT_SYMBOL_GPL(alloc_dax_region);
+
+static ssize_t size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+	unsigned long long size = resource_size(&dev_dax->region->res);
+
+	return sprintf(buf, "%llu\n", size);
+}
+static DEVICE_ATTR_RO(size);
+
+static int dev_dax_target_node(struct dev_dax *dev_dax)
+{
+	struct dax_region *dax_region = dev_dax->region;
+
+	return dax_region->target_node;
+}
+
+static ssize_t target_node_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+
+	return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
+}
+static DEVICE_ATTR_RO(target_node);
+
+static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	/*
+	 * We only ever expect to handle device-dax instances, i.e. the
+	 * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
+	 */
+	return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+
+	if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
+		return 0;
+	return a->mode;
+}
+
+static struct attribute *dev_dax_attributes[] = {
+	&dev_attr_modalias.attr,
+	&dev_attr_size.attr,
+	&dev_attr_target_node.attr,
+	NULL,
+};
+
+static const struct attribute_group dev_dax_attribute_group = {
+	.attrs = dev_dax_attributes,
+	.is_visible = dev_dax_visible,
+};
+
+static const struct attribute_group *dax_attribute_groups[] = {
+	&dev_dax_attribute_group,
+	NULL,
+};
+
+void kill_dev_dax(struct dev_dax *dev_dax)
+{
+	struct dax_device *dax_dev = dev_dax->dax_dev;
+	struct inode *inode = dax_inode(dax_dev);
+
+	kill_dax(dax_dev);
+	unmap_mapping_range(inode->i_mapping, 0, 0, 1);
+}
+EXPORT_SYMBOL_GPL(kill_dev_dax);
+
+static void dev_dax_release(struct device *dev)
+{
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+	struct dax_region *dax_region = dev_dax->region;
+	struct dax_device *dax_dev = dev_dax->dax_dev;
+
+	dax_region_put(dax_region);
+	put_dax(dax_dev);
+	kfree(dev_dax);
+}
+
+static void unregister_dev_dax(void *dev)
+{
+	struct dev_dax *dev_dax = to_dev_dax(dev);
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	kill_dev_dax(dev_dax);
+	device_del(dev);
+	put_device(dev);
+}
+
+struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
+		struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
+{
+	struct device *parent = dax_region->dev;
+	struct dax_device *dax_dev;
+	struct dev_dax *dev_dax;
+	struct inode *inode;
+	struct device *dev;
+	int rc = -ENOMEM;
+
+	if (id < 0)
+		return ERR_PTR(-EINVAL);
+
+	dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
+	if (!dev_dax)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
+
+	/*
+	 * No 'host' or dax_operations since there is no access to this
+	 * device outside of mmap of the resulting character device.
+	 */
+	dax_dev = alloc_dax(dev_dax, NULL, NULL);
+	if (!dax_dev)
+		goto err;
+
+	/* a device_dax instance is dead while the driver is not attached */
+	kill_dax(dax_dev);
+
+	/* from here on we're committed to teardown via dax_dev_release() */
+	dev = &dev_dax->dev;
+	device_initialize(dev);
+
+	dev_dax->dax_dev = dax_dev;
+	dev_dax->region = dax_region;
+	dev_dax->target_node = dax_region->target_node;
+	kref_get(&dax_region->kref);
+
+	inode = dax_inode(dax_dev);
+	dev->devt = inode->i_rdev;
+	if (subsys == DEV_DAX_BUS)
+		dev->bus = &dax_bus_type;
+	else
+		dev->class = dax_class;
+	dev->parent = parent;
+	dev->groups = dax_attribute_groups;
+	dev->release = dev_dax_release;
+	dev_set_name(dev, "dax%d.%d", dax_region->id, id);
+
+	rc = device_add(dev);
+	if (rc) {
+		kill_dev_dax(dev_dax);
+		put_device(dev);
+		return ERR_PTR(rc);
+	}
+
+	rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return dev_dax;
+
+ err:
+	kfree(dev_dax);
+
+	return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
+
+static int match_always_count;
+
+int __dax_driver_register(struct dax_device_driver *dax_drv,
+		struct module *module, const char *mod_name)
+{
+	struct device_driver *drv = &dax_drv->drv;
+	int rc = 0;
+
+	INIT_LIST_HEAD(&dax_drv->ids);
+	drv->owner = module;
+	drv->name = mod_name;
+	drv->mod_name = mod_name;
+	drv->bus = &dax_bus_type;
+
+	/* there can only be one default driver */
+	mutex_lock(&dax_bus_lock);
+	match_always_count += dax_drv->match_always;
+	if (match_always_count > 1) {
+		match_always_count--;
+		WARN_ON(1);
+		rc = -EINVAL;
+	}
+	mutex_unlock(&dax_bus_lock);
+	if (rc)
+		return rc;
+	return driver_register(drv);
+}
+EXPORT_SYMBOL_GPL(__dax_driver_register);
+
+void dax_driver_unregister(struct dax_device_driver *dax_drv)
+{
+	struct device_driver *drv = &dax_drv->drv;
+	struct dax_id *dax_id, *_id;
+
+	mutex_lock(&dax_bus_lock);
+	match_always_count -= dax_drv->match_always;
+	list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
+		list_del(&dax_id->list);
+		kfree(dax_id);
+	}
+	mutex_unlock(&dax_bus_lock);
+	driver_unregister(drv);
+}
+EXPORT_SYMBOL_GPL(dax_driver_unregister);
+
+int __init dax_bus_init(void)
+{
+	int rc;
+
+	if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
+		dax_class = class_create(THIS_MODULE, "dax");
+		if (IS_ERR(dax_class))
+			return PTR_ERR(dax_class);
+	}
+
+	rc = bus_register(&dax_bus_type);
+	if (rc)
+		class_destroy(dax_class);
+	return rc;
+}
+
+void __exit dax_bus_exit(void)
+{
+	bus_unregister(&dax_bus_type);
+	class_destroy(dax_class);
+}