/*
   * Handle async block request by crypto hardware engine.
   *
   * Copyright (C) 2016 Linaro, Inc.
   *
   * Author: Baolin Wang <baolin.wang@linaro.org>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option)
   * any later version.
   *
   */
  
  #include <linux/err.h>
  #include <linux/delay.h>

  #include <crypto/engine.h>

  #include <crypto/internal/hash.h>

  #include "internal.h"
  
  #define CRYPTO_ENGINE_MAX_QLEN 10

  /**
   * crypto_pump_requests - dequeue one request from engine queue to process
   * @engine: the hardware engine
   * @in_kthread: true if we are in the context of the request pump thread
   *
   * This function checks if there is any request in the engine queue that
   * needs processing and if so call out to the driver to initialize hardware
   * and handle each request.
   */
  static void crypto_pump_requests(struct crypto_engine *engine,
  				 bool in_kthread)
  {
  	struct crypto_async_request *async_req, *backlog;

  	struct ahash_request *hreq;
  	struct ablkcipher_request *breq;

  	unsigned long flags;
  	bool was_busy = false;

  	int ret, rtype;

  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  
  	/* Make sure we are not already running a request */
  	if (engine->cur_req)
  		goto out;
  
  	/* If another context is idling then defer */
  	if (engine->idling) {

  		kthread_queue_work(&engine->kworker, &engine->pump_requests);

  		goto out;
  	}
  
  	/* Check if the engine queue is idle */
  	if (!crypto_queue_len(&engine->queue) || !engine->running) {
  		if (!engine->busy)
  			goto out;
  
  		/* Only do teardown in the thread */
  		if (!in_kthread) {

  			kthread_queue_work(&engine->kworker,

  					   &engine->pump_requests);
  			goto out;
  		}
  
  		engine->busy = false;
  		engine->idling = true;
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  
  		if (engine->unprepare_crypt_hardware &&
  		    engine->unprepare_crypt_hardware(engine))
  			pr_err("failed to unprepare crypt hardware
  ");
  
  		spin_lock_irqsave(&engine->queue_lock, flags);
  		engine->idling = false;
  		goto out;
  	}
  
  	/* Get the fist request from the engine queue to handle */
  	backlog = crypto_get_backlog(&engine->queue);
  	async_req = crypto_dequeue_request(&engine->queue);
  	if (!async_req)
  		goto out;

  	engine->cur_req = async_req;

  	if (backlog)
  		backlog->complete(backlog, -EINPROGRESS);
  
  	if (engine->busy)
  		was_busy = true;
  	else
  		engine->busy = true;
  
  	spin_unlock_irqrestore(&engine->queue_lock, flags);

  	rtype = crypto_tfm_alg_type(engine->cur_req->tfm);

  	/* Until here we get the request need to be encrypted successfully */
  	if (!was_busy && engine->prepare_crypt_hardware) {
  		ret = engine->prepare_crypt_hardware(engine);
  		if (ret) {
  			pr_err("failed to prepare crypt hardware
  ");
  			goto req_err;
  		}
  	}

  	switch (rtype) {
  	case CRYPTO_ALG_TYPE_AHASH:
  		hreq = ahash_request_cast(engine->cur_req);
  		if (engine->prepare_hash_request) {
  			ret = engine->prepare_hash_request(engine, hreq);
  			if (ret) {
  				pr_err("failed to prepare request: %d
  ", ret);
  				goto req_err;
  			}
  			engine->cur_req_prepared = true;
  		}
  		ret = engine->hash_one_request(engine, hreq);

  		if (ret) {

  			pr_err("failed to hash one request from queue
  ");

  			goto req_err;
  		}

  		return;
  	case CRYPTO_ALG_TYPE_ABLKCIPHER:
  		breq = ablkcipher_request_cast(engine->cur_req);
  		if (engine->prepare_cipher_request) {
  			ret = engine->prepare_cipher_request(engine, breq);
  			if (ret) {
  				pr_err("failed to prepare request: %d
  ", ret);
  				goto req_err;
  			}
  			engine->cur_req_prepared = true;
  		}
  		ret = engine->cipher_one_request(engine, breq);
  		if (ret) {
  			pr_err("failed to cipher one request from queue
  ");
  			goto req_err;
  		}
  		return;
  	default:
  		pr_err("failed to prepare request of unknown type
  ");
  		return;

  	}

  
  req_err:

  	switch (rtype) {
  	case CRYPTO_ALG_TYPE_AHASH:
  		hreq = ahash_request_cast(engine->cur_req);
  		crypto_finalize_hash_request(engine, hreq, ret);
  		break;
  	case CRYPTO_ALG_TYPE_ABLKCIPHER:
  		breq = ablkcipher_request_cast(engine->cur_req);
  		crypto_finalize_cipher_request(engine, breq, ret);
  		break;
  	}

  	return;
  
  out:
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  }
  
  static void crypto_pump_work(struct kthread_work *work)
  {
  	struct crypto_engine *engine =
  		container_of(work, struct crypto_engine, pump_requests);
  
  	crypto_pump_requests(engine, true);
  }
  
  /**

   * crypto_transfer_cipher_request - transfer the new request into the
   * enginequeue

   * @engine: the hardware engine
   * @req: the request need to be listed into the engine queue
   */

  int crypto_transfer_cipher_request(struct crypto_engine *engine,
  				   struct ablkcipher_request *req,
  				   bool need_pump)

  {
  	unsigned long flags;
  	int ret;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  
  	if (!engine->running) {
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  		return -ESHUTDOWN;
  	}
  
  	ret = ablkcipher_enqueue_request(&engine->queue, req);
  
  	if (!engine->busy && need_pump)

  		kthread_queue_work(&engine->kworker, &engine->pump_requests);

  
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  	return ret;
  }

  EXPORT_SYMBOL_GPL(crypto_transfer_cipher_request);
  
  /**
   * crypto_transfer_cipher_request_to_engine - transfer one request to list
   * into the engine queue
   * @engine: the hardware engine
   * @req: the request need to be listed into the engine queue
   */
  int crypto_transfer_cipher_request_to_engine(struct crypto_engine *engine,
  					     struct ablkcipher_request *req)
  {
  	return crypto_transfer_cipher_request(engine, req, true);
  }
  EXPORT_SYMBOL_GPL(crypto_transfer_cipher_request_to_engine);
  
  /**
   * crypto_transfer_hash_request - transfer the new request into the
   * enginequeue
   * @engine: the hardware engine
   * @req: the request need to be listed into the engine queue
   */
  int crypto_transfer_hash_request(struct crypto_engine *engine,
  				 struct ahash_request *req, bool need_pump)
  {
  	unsigned long flags;
  	int ret;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  
  	if (!engine->running) {
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  		return -ESHUTDOWN;
  	}
  
  	ret = ahash_enqueue_request(&engine->queue, req);
  
  	if (!engine->busy && need_pump)

  		kthread_queue_work(&engine->kworker, &engine->pump_requests);

  
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(crypto_transfer_hash_request);

  
  /**

   * crypto_transfer_hash_request_to_engine - transfer one request to list
   * into the engine queue

   * @engine: the hardware engine
   * @req: the request need to be listed into the engine queue
   */

  int crypto_transfer_hash_request_to_engine(struct crypto_engine *engine,
  					   struct ahash_request *req)

  {

  	return crypto_transfer_hash_request(engine, req, true);

  }

  EXPORT_SYMBOL_GPL(crypto_transfer_hash_request_to_engine);

  
  /**

   * crypto_finalize_cipher_request - finalize one request if the request is done

   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */

  void crypto_finalize_cipher_request(struct crypto_engine *engine,
  				    struct ablkcipher_request *req, int err)

  {
  	unsigned long flags;
  	bool finalize_cur_req = false;
  	int ret;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);

  	if (engine->cur_req == &req->base)

  		finalize_cur_req = true;
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  
  	if (finalize_cur_req) {

  		if (engine->cur_req_prepared &&
  		    engine->unprepare_cipher_request) {
  			ret = engine->unprepare_cipher_request(engine, req);

  			if (ret)
  				pr_err("failed to unprepare request
  ");
  		}

  		spin_lock_irqsave(&engine->queue_lock, flags);
  		engine->cur_req = NULL;
  		engine->cur_req_prepared = false;
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  	}
  
  	req->base.complete(&req->base, err);

  	kthread_queue_work(&engine->kworker, &engine->pump_requests);

  }
  EXPORT_SYMBOL_GPL(crypto_finalize_cipher_request);
  
  /**
   * crypto_finalize_hash_request - finalize one request if the request is done
   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */
  void crypto_finalize_hash_request(struct crypto_engine *engine,
  				  struct ahash_request *req, int err)
  {
  	unsigned long flags;
  	bool finalize_cur_req = false;
  	int ret;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  	if (engine->cur_req == &req->base)
  		finalize_cur_req = true;
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  
  	if (finalize_cur_req) {
  		if (engine->cur_req_prepared &&
  		    engine->unprepare_hash_request) {
  			ret = engine->unprepare_hash_request(engine, req);
  			if (ret)
  				pr_err("failed to unprepare request
  ");
  		}

  		spin_lock_irqsave(&engine->queue_lock, flags);
  		engine->cur_req = NULL;
  		engine->cur_req_prepared = false;
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  	}
  
  	req->base.complete(&req->base, err);

  	kthread_queue_work(&engine->kworker, &engine->pump_requests);

  }

  EXPORT_SYMBOL_GPL(crypto_finalize_hash_request);

  
  /**
   * crypto_engine_start - start the hardware engine
   * @engine: the hardware engine need to be started
   *
   * Return 0 on success, else on fail.
   */
  int crypto_engine_start(struct crypto_engine *engine)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  
  	if (engine->running || engine->busy) {
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  		return -EBUSY;
  	}
  
  	engine->running = true;
  	spin_unlock_irqrestore(&engine->queue_lock, flags);

  	kthread_queue_work(&engine->kworker, &engine->pump_requests);

  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(crypto_engine_start);
  
  /**
   * crypto_engine_stop - stop the hardware engine
   * @engine: the hardware engine need to be stopped
   *
   * Return 0 on success, else on fail.
   */
  int crypto_engine_stop(struct crypto_engine *engine)
  {
  	unsigned long flags;

  	unsigned int limit = 500;

  	int ret = 0;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  
  	/*
  	 * If the engine queue is not empty or the engine is on busy state,
  	 * we need to wait for a while to pump the requests of engine queue.
  	 */
  	while ((crypto_queue_len(&engine->queue) || engine->busy) && limit--) {
  		spin_unlock_irqrestore(&engine->queue_lock, flags);
  		msleep(20);
  		spin_lock_irqsave(&engine->queue_lock, flags);
  	}
  
  	if (crypto_queue_len(&engine->queue) || engine->busy)
  		ret = -EBUSY;
  	else
  		engine->running = false;
  
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  
  	if (ret)
  		pr_warn("could not stop engine
  ");
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(crypto_engine_stop);
  
  /**
   * crypto_engine_alloc_init - allocate crypto hardware engine structure and
   * initialize it.
   * @dev: the device attached with one hardware engine
   * @rt: whether this queue is set to run as a realtime task
   *
   * This must be called from context that can sleep.
   * Return: the crypto engine structure on success, else NULL.
   */
  struct crypto_engine *crypto_engine_alloc_init(struct device *dev, bool rt)
  {
  	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
  	struct crypto_engine *engine;
  
  	if (!dev)
  		return NULL;
  
  	engine = devm_kzalloc(dev, sizeof(*engine), GFP_KERNEL);
  	if (!engine)
  		return NULL;
  
  	engine->rt = rt;
  	engine->running = false;
  	engine->busy = false;
  	engine->idling = false;
  	engine->cur_req_prepared = false;
  	engine->priv_data = dev;
  	snprintf(engine->name, sizeof(engine->name),
  		 "%s-engine", dev_name(dev));
  
  	crypto_init_queue(&engine->queue, CRYPTO_ENGINE_MAX_QLEN);
  	spin_lock_init(&engine->queue_lock);

  	kthread_init_worker(&engine->kworker);

  	engine->kworker_task = kthread_run(kthread_worker_fn,
  					   &engine->kworker, "%s",
  					   engine->name);
  	if (IS_ERR(engine->kworker_task)) {
  		dev_err(dev, "failed to create crypto request pump task
  ");
  		return NULL;
  	}

  	kthread_init_work(&engine->pump_requests, crypto_pump_work);

  
  	if (engine->rt) {
  		dev_info(dev, "will run requests pump with realtime priority
  ");
  		sched_setscheduler(engine->kworker_task, SCHED_FIFO, &param);
  	}
  
  	return engine;
  }
  EXPORT_SYMBOL_GPL(crypto_engine_alloc_init);
  
  /**
   * crypto_engine_exit - free the resources of hardware engine when exit
   * @engine: the hardware engine need to be freed
   *
   * Return 0 for success.
   */
  int crypto_engine_exit(struct crypto_engine *engine)
  {
  	int ret;
  
  	ret = crypto_engine_stop(engine);
  	if (ret)
  		return ret;

  	kthread_flush_worker(&engine->kworker);

  	kthread_stop(engine->kworker_task);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(crypto_engine_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Crypto hardware engine framework");