/*
 * Thunderbolt bus support
 *
 * Copyright (C) 2017, Intel Corporation
 * Author:  Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * 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.
 */

#include <linux/device.h>
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <crypto/hash.h>

#include "tb.h"

static DEFINE_IDA(tb_domain_ida);

static const char * const tb_security_names[] = {
	[TB_SECURITY_NONE] = "none",
	[TB_SECURITY_USER] = "user",
	[TB_SECURITY_SECURE] = "secure",
	[TB_SECURITY_DPONLY] = "dponly",
};

static ssize_t security_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	struct tb *tb = container_of(dev, struct tb, dev);

	return sprintf(buf, "%s\n", tb_security_names[tb->security_level]);
}
static DEVICE_ATTR_RO(security);

static struct attribute *domain_attrs[] = {
	&dev_attr_security.attr,
	NULL,
};

static struct attribute_group domain_attr_group = {
	.attrs = domain_attrs,
};

static const struct attribute_group *domain_attr_groups[] = {
	&domain_attr_group,
	NULL,
};

struct bus_type tb_bus_type = {
	.name = "thunderbolt",
};

static void tb_domain_release(struct device *dev)
{
	struct tb *tb = container_of(dev, struct tb, dev);

	tb_ctl_free(tb->ctl);
	destroy_workqueue(tb->wq);
	ida_simple_remove(&tb_domain_ida, tb->index);
	mutex_destroy(&tb->lock);
	kfree(tb);
}

struct device_type tb_domain_type = {
	.name = "thunderbolt_domain",
	.release = tb_domain_release,
};

/**
 * tb_domain_alloc() - Allocate a domain
 * @nhi: Pointer to the host controller
 * @privsize: Size of the connection manager private data
 *
 * Allocates and initializes a new Thunderbolt domain. Connection
 * managers are expected to call this and then fill in @cm_ops
 * accordingly.
 *
 * Call tb_domain_put() to release the domain before it has been added
 * to the system.
 *
 * Return: allocated domain structure on %NULL in case of error
 */
struct tb *tb_domain_alloc(struct tb_nhi *nhi, size_t privsize)
{
	struct tb *tb;

	/*
	 * Make sure the structure sizes map with that the hardware
	 * expects because bit-fields are being used.
	 */
	BUILD_BUG_ON(sizeof(struct tb_regs_switch_header) != 5 * 4);
	BUILD_BUG_ON(sizeof(struct tb_regs_port_header) != 8 * 4);
	BUILD_BUG_ON(sizeof(struct tb_regs_hop) != 2 * 4);

	tb = kzalloc(sizeof(*tb) + privsize, GFP_KERNEL);
	if (!tb)
		return NULL;

	tb->nhi = nhi;
	mutex_init(&tb->lock);

	tb->index = ida_simple_get(&tb_domain_ida, 0, 0, GFP_KERNEL);
	if (tb->index < 0)
		goto err_free;

	tb->wq = alloc_ordered_workqueue("thunderbolt%d", 0, tb->index);
	if (!tb->wq)
		goto err_remove_ida;

	tb->dev.parent = &nhi->pdev->dev;
	tb->dev.bus = &tb_bus_type;
	tb->dev.type = &tb_domain_type;
	tb->dev.groups = domain_attr_groups;
	dev_set_name(&tb->dev, "domain%d", tb->index);
	device_initialize(&tb->dev);

	return tb;

err_remove_ida:
	ida_simple_remove(&tb_domain_ida, tb->index);
err_free:
	kfree(tb);

	return NULL;
}

static void tb_domain_event_cb(void *data, enum tb_cfg_pkg_type type,
			       const void *buf, size_t size)
{
	struct tb *tb = data;

	if (!tb->cm_ops->handle_event) {
		tb_warn(tb, "domain does not have event handler\n");
		return;
	}

	tb->cm_ops->handle_event(tb, type, buf, size);
}

/**
 * tb_domain_add() - Add domain to the system
 * @tb: Domain to add
 *
 * Starts the domain and adds it to the system. Hotplugging devices will
 * work after this has been returned successfully. In order to remove
 * and release the domain after this function has been called, call
 * tb_domain_remove().
 *
 * Return: %0 in case of success and negative errno in case of error
 */
int tb_domain_add(struct tb *tb)
{
	int ret;

	if (WARN_ON(!tb->cm_ops))
		return -EINVAL;

	mutex_lock(&tb->lock);

	tb->ctl = tb_ctl_alloc(tb->nhi, tb_domain_event_cb, tb);
	if (!tb->ctl) {
		ret = -ENOMEM;
		goto err_unlock;
	}

	/*
	 * tb_schedule_hotplug_handler may be called as soon as the config
	 * channel is started. Thats why we have to hold the lock here.
	 */
	tb_ctl_start(tb->ctl);

	if (tb->cm_ops->driver_ready) {
		ret = tb->cm_ops->driver_ready(tb);
		if (ret)
			goto err_ctl_stop;
	}

	ret = device_add(&tb->dev);
	if (ret)
		goto err_ctl_stop;

	/* Start the domain */
	if (tb->cm_ops->start) {
		ret = tb->cm_ops->start(tb);
		if (ret)
			goto err_domain_del;
	}

	/* This starts event processing */
	mutex_unlock(&tb->lock);

	return 0;

err_domain_del:
	device_del(&tb->dev);
err_ctl_stop:
	tb_ctl_stop(tb->ctl);
err_unlock:
	mutex_unlock(&tb->lock);

	return ret;
}

/**
 * tb_domain_remove() - Removes and releases a domain
 * @tb: Domain to remove
 *
 * Stops the domain, removes it from the system and releases all
 * resources once the last reference has been released.
 */
void tb_domain_remove(struct tb *tb)
{
	mutex_lock(&tb->lock);
	if (tb->cm_ops->stop)
		tb->cm_ops->stop(tb);
	/* Stop the domain control traffic */
	tb_ctl_stop(tb->ctl);
	mutex_unlock(&tb->lock);

	flush_workqueue(tb->wq);
	device_unregister(&tb->dev);
}

/**
 * tb_domain_suspend_noirq() - Suspend a domain
 * @tb: Domain to suspend
 *
 * Suspends all devices in the domain and stops the control channel.
 */
int tb_domain_suspend_noirq(struct tb *tb)
{
	int ret = 0;

	/*
	 * The control channel interrupt is left enabled during suspend
	 * and taking the lock here prevents any events happening before
	 * we actually have stopped the domain and the control channel.
	 */
	mutex_lock(&tb->lock);
	if (tb->cm_ops->suspend_noirq)
		ret = tb->cm_ops->suspend_noirq(tb);
	if (!ret)
		tb_ctl_stop(tb->ctl);
	mutex_unlock(&tb->lock);

	return ret;
}

/**
 * tb_domain_resume_noirq() - Resume a domain
 * @tb: Domain to resume
 *
 * Re-starts the control channel, and resumes all devices connected to
 * the domain.
 */
int tb_domain_resume_noirq(struct tb *tb)
{
	int ret = 0;

	mutex_lock(&tb->lock);
	tb_ctl_start(tb->ctl);
	if (tb->cm_ops->resume_noirq)
		ret = tb->cm_ops->resume_noirq(tb);
	mutex_unlock(&tb->lock);

	return ret;
}

int tb_domain_suspend(struct tb *tb)
{
	int ret;

	mutex_lock(&tb->lock);
	if (tb->cm_ops->suspend) {
		ret = tb->cm_ops->suspend(tb);
		if (ret) {
			mutex_unlock(&tb->lock);
			return ret;
		}
	}
	mutex_unlock(&tb->lock);
	return 0;
}

void tb_domain_complete(struct tb *tb)
{
	mutex_lock(&tb->lock);
	if (tb->cm_ops->complete)
		tb->cm_ops->complete(tb);
	mutex_unlock(&tb->lock);
}

/**
 * tb_domain_approve_switch() - Approve switch
 * @tb: Domain the switch belongs to
 * @sw: Switch to approve
 *
 * This will approve switch by connection manager specific means. In
 * case of success the connection manager will create tunnels for all
 * supported protocols.
 */
int tb_domain_approve_switch(struct tb *tb, struct tb_switch *sw)
{
	struct tb_switch *parent_sw;

	if (!tb->cm_ops->approve_switch)
		return -EPERM;

	/* The parent switch must be authorized before this one */
	parent_sw = tb_to_switch(sw->dev.parent);
	if (!parent_sw || !parent_sw->authorized)
		return -EINVAL;

	return tb->cm_ops->approve_switch(tb, sw);
}

/**
 * tb_domain_approve_switch_key() - Approve switch and add key
 * @tb: Domain the switch belongs to
 * @sw: Switch to approve
 *
 * For switches that support secure connect, this function first adds
 * key to the switch NVM using connection manager specific means. If
 * adding the key is successful, the switch is approved and connected.
 *
 * Return: %0 on success and negative errno in case of failure.
 */
int tb_domain_approve_switch_key(struct tb *tb, struct tb_switch *sw)
{
	struct tb_switch *parent_sw;
	int ret;

	if (!tb->cm_ops->approve_switch || !tb->cm_ops->add_switch_key)
		return -EPERM;

	/* The parent switch must be authorized before this one */
	parent_sw = tb_to_switch(sw->dev.parent);
	if (!parent_sw || !parent_sw->authorized)
		return -EINVAL;

	ret = tb->cm_ops->add_switch_key(tb, sw);
	if (ret)
		return ret;

	return tb->cm_ops->approve_switch(tb, sw);
}

/**
 * tb_domain_challenge_switch_key() - Challenge and approve switch
 * @tb: Domain the switch belongs to
 * @sw: Switch to approve
 *
 * For switches that support secure connect, this function generates
 * random challenge and sends it to the switch. The switch responds to
 * this and if the response matches our random challenge, the switch is
 * approved and connected.
 *
 * Return: %0 on success and negative errno in case of failure.
 */
int tb_domain_challenge_switch_key(struct tb *tb, struct tb_switch *sw)
{
	u8 challenge[TB_SWITCH_KEY_SIZE];
	u8 response[TB_SWITCH_KEY_SIZE];
	u8 hmac[TB_SWITCH_KEY_SIZE];
	struct tb_switch *parent_sw;
	struct crypto_shash *tfm;
	struct shash_desc *shash;
	int ret;

	if (!tb->cm_ops->approve_switch || !tb->cm_ops->challenge_switch_key)
		return -EPERM;

	/* The parent switch must be authorized before this one */
	parent_sw = tb_to_switch(sw->dev.parent);
	if (!parent_sw || !parent_sw->authorized)
		return -EINVAL;

	get_random_bytes(challenge, sizeof(challenge));
	ret = tb->cm_ops->challenge_switch_key(tb, sw, challenge, response);
	if (ret)
		return ret;

	tfm = crypto_alloc_shash("hmac(sha256)", 0, 0);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	ret = crypto_shash_setkey(tfm, sw->key, TB_SWITCH_KEY_SIZE);
	if (ret)
		goto err_free_tfm;

	shash = kzalloc(sizeof(*shash) + crypto_shash_descsize(tfm),
			GFP_KERNEL);
	if (!shash) {
		ret = -ENOMEM;
		goto err_free_tfm;
	}

	shash->tfm = tfm;
	shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	memset(hmac, 0, sizeof(hmac));
	ret = crypto_shash_digest(shash, challenge, sizeof(hmac), hmac);
	if (ret)
		goto err_free_shash;

	/* The returned HMAC must match the one we calculated */
	if (memcmp(response, hmac, sizeof(hmac))) {
		ret = -EKEYREJECTED;
		goto err_free_shash;
	}

	crypto_free_shash(tfm);
	kfree(shash);

	return tb->cm_ops->approve_switch(tb, sw);

err_free_shash:
	kfree(shash);
err_free_tfm:
	crypto_free_shash(tfm);

	return ret;
}

/**
 * tb_domain_disconnect_pcie_paths() - Disconnect all PCIe paths
 * @tb: Domain whose PCIe paths to disconnect
 *
 * This needs to be called in preparation for NVM upgrade of the host
 * controller. Makes sure all PCIe paths are disconnected.
 *
 * Return %0 on success and negative errno in case of error.
 */
int tb_domain_disconnect_pcie_paths(struct tb *tb)
{
	if (!tb->cm_ops->disconnect_pcie_paths)
		return -EPERM;

	return tb->cm_ops->disconnect_pcie_paths(tb);
}

int tb_domain_init(void)
{
	return bus_register(&tb_bus_type);
}

void tb_domain_exit(void)
{
	bus_unregister(&tb_bus_type);
	ida_destroy(&tb_domain_ida);
	tb_switch_exit();
}