// 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 unsigned long long dev_dax_resource(struct dev_dax *dev_dax)
{
        struct dax_region *dax_region = dev_dax->region;

        return dax_region->res.start;
}

static ssize_t resource_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct dev_dax *dev_dax = to_dev_dax(dev);

        return sprintf(buf, "%#llx\n", dev_dax_resource(dev_dax));
}
static DEVICE_ATTR_RO(resource);

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;
        if (a == &dev_attr_resource.attr)
                return 0400;
        return a->mode;
}

static struct attribute *dev_dax_attributes[] = {
        &dev_attr_modalias.attr,
        &dev_attr_size.attr,
        &dev_attr_target_node.attr,
        &dev_attr_resource.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, DAXDEV_F_SYNC);
        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);
}