path: root/drivers/dax/bus.c

// 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 <linux/io.h>
#include "dax-private.h"
#include "bus.h"

static DEFINE_MUTEX(dax_bus_lock);

/*
 * All changes to the dax region configuration occur with this lock held
 * for write.
 */
DECLARE_RWSEM(dax_region_rwsem);

/*
 * All changes to the dax device configuration occur with this lock held
 * for write.
 */
DECLARE_RWSEM(dax_dev_rwsem);

#define DAX_NAME_LEN 30
struct dax_id {
	struct list_head list;
	char dev_name[DAX_NAME_LEN];
};

static int dax_bus_uevent(const 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);
}

#define to_dax_drv(__drv)	container_of_const(__drv, struct dax_device_driver, drv)

static struct dax_id *__dax_match_id(const 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(const 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;
}

static int dax_match_type(const struct dax_device_driver *dax_drv, struct device *dev)
{
	enum dax_driver_type type = DAXDRV_DEVICE_TYPE;
	struct dev_dax *dev_dax = to_dev_dax(dev);

	if (dev_dax->region->res.flags & IORESOURCE_DAX_KMEM)
		type = DAXDRV_KMEM_TYPE;

	if (dax_drv->type == type)
		return 1;

	/* default to device mode if dax_kmem is disabled */
	if (dax_drv->type == DAXDRV_DEVICE_TYPE &&
	    !IS_ENABLED(CONFIG_DEV_DAX_KMEM))
		return 1;

	return 0;
}

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) {
				strscpy(dax_id->dev_name, buf, DAX_NAME_LEN);
				list_add(&dax_id->list, &dax_drv->ids);
			} else
				rc = -ENOMEM;
		}
	} else if (action == ID_REMOVE) {
		list_del(&dax_id->list);
		kfree(dax_id);
	}
	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, const struct device_driver *drv);

/*
 * Static dax regions are regions created by an external subsystem
 * nvdimm where a single range is assigned. Its boundaries are by the external
 * subsystem and are usually limited to one physical memory range. For example,
 * for PMEM it is usually defined by NVDIMM Namespace boundaries (i.e. a
 * single contiguous range)
 *
 * On dynamic dax regions, the assigned region can be partitioned by dax core
 * into multiple subdivisions. A subdivision is represented into one
 * /dev/daxN.M device composed by one or more potentially discontiguous ranges.
 *
 * When allocating a dax region, drivers must set whether it's static
 * (IORESOURCE_DAX_STATIC).  On static dax devices, the @pgmap is pre-assigned
 * to dax core when calling devm_create_dev_dax(), whereas in dynamic dax
 * devices it is NULL but afterwards allocated by dax core on device ->probe().
 * Care is needed to make sure that dynamic dax devices are torn down with a
 * cleared @pgmap field (see kill_dev_dax()).
 */
static bool is_static(struct dax_region *dax_region)
{
	return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
}

bool static_dev_dax(struct dev_dax *dev_dax)
{
	return is_static(dev_dax->region);
}
EXPORT_SYMBOL_GPL(static_dev_dax);

static u64 dev_dax_size(struct dev_dax *dev_dax)
{
	u64 size = 0;
	int i;

	lockdep_assert_held(&dax_dev_rwsem);

	for (i = 0; i < dev_dax->nr_range; i++)
		size += range_len(&dev_dax->ranges[i].range);

	return size;
}

static int dax_bus_probe(struct device *dev)
{
	struct dax_device_driver *dax_drv = to_dax_drv(dev->driver);
	struct dev_dax *dev_dax = to_dev_dax(dev);
	struct dax_region *dax_region = dev_dax->region;
	int rc;
	u64 size;

	rc = down_read_interruptible(&dax_dev_rwsem);
	if (rc)
		return rc;
	size = dev_dax_size(dev_dax);
	up_read(&dax_dev_rwsem);

	if (size == 0 || dev_dax->id < 0)
		return -ENXIO;

	rc = dax_drv->probe(dev_dax);

	if (rc || is_static(dax_region))
		return rc;

	/*
	 * Track new see