/*
   * 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 <uapi/linux/sched/types.h>

  #include "internal.h"
  
  #define CRYPTO_ENGINE_MAX_QLEN 10

  /**

   * crypto_finalize_request - finalize one request if the request is done
   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */
  static void crypto_finalize_request(struct crypto_engine *engine,
  			     struct crypto_async_request *req, int err)
  {
  	unsigned long flags;
  	bool finalize_cur_req = false;
  	int ret;
  	struct crypto_engine_ctx *enginectx;
  
  	spin_lock_irqsave(&engine->queue_lock, flags);
  	if (engine->cur_req == req)
  		finalize_cur_req = true;
  	spin_unlock_irqrestore(&engine->queue_lock, flags);
  
  	if (finalize_cur_req) {
  		enginectx = crypto_tfm_ctx(req->tfm);
  		if (engine->cur_req_prepared &&
  		    enginectx->op.unprepare_request) {
  			ret = enginectx->op.unprepare_request(engine, req);
  			if (ret)
  				dev_err(engine->dev, "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->complete(req, err);
  
  	kthread_queue_work(engine->kworker, &engine->pump_requests);
  }
  
  /**

   * 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;

  	unsigned long flags;
  	bool was_busy = false;

  	int ret;
  	struct crypto_engine_ctx *enginectx;

  
  	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))

  			dev_err(engine->dev, "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);
  
  	/* 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) {

  			dev_err(engine->dev, "failed to prepare crypt hardware
  ");

  			goto req_err;
  		}
  	}

  	enginectx = crypto_tfm_ctx(async_req->tfm);
  
  	if (enginectx->op.prepare_request) {
  		ret = enginectx->op.prepare_request(engine, async_req);

  		if (ret) {

  			dev_err(engine->dev, "failed to prepare request: %d
  ",
  				ret);

  			goto req_err;
  		}

  		engine->cur_req_prepared = true;
  	}
  	if (!enginectx->op.do_one_request) {
  		dev_err(engine->dev, "failed to do request
  ");
  		ret = -EINVAL;
  		goto req_err;

  	}

  	ret = enginectx->op.do_one_request(engine, async_req);
  	if (ret) {
  		dev_err(engine->dev, "Failed to do one request from queue: %d
  ", ret);
  		goto req_err;
  	}
  	return;

  
  req_err:

  	crypto_finalize_request(engine, async_req, ret);

  	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_request - transfer the new request into the engine queue

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

  static int crypto_transfer_request(struct crypto_engine *engine,
  				   struct crypto_async_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 = crypto_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;
  }

  
  /**

   * crypto_transfer_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
   */

  static int crypto_transfer_request_to_engine(struct crypto_engine *engine,
  					     struct crypto_async_request *req)

  {

  	return crypto_transfer_request(engine, req, true);

  }

  
  /**

   * crypto_transfer_ablkcipher_request_to_engine - transfer one ablkcipher_request
   * to list into the engine queue

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

   * TODO: Remove this function when skcipher conversion is finished

   */

  int crypto_transfer_ablkcipher_request_to_engine(struct crypto_engine *engine,
  						 struct ablkcipher_request *req)

  {

  	return crypto_transfer_request_to_engine(engine, &req->base);
  }
  EXPORT_SYMBOL_GPL(crypto_transfer_ablkcipher_request_to_engine);

  /**
   * crypto_transfer_aead_request_to_engine - transfer one aead_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_aead_request_to_engine(struct crypto_engine *engine,
  					   struct aead_request *req)
  {
  	return crypto_transfer_request_to_engine(engine, &req->base);
  }
  EXPORT_SYMBOL_GPL(crypto_transfer_aead_request_to_engine);

  /**
   * crypto_transfer_akcipher_request_to_engine - transfer one akcipher_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_akcipher_request_to_engine(struct crypto_engine *engine,
  					       struct akcipher_request *req)
  {
  	return crypto_transfer_request_to_engine(engine, &req->base);

  }

  EXPORT_SYMBOL_GPL(crypto_transfer_akcipher_request_to_engine);

  
  /**

   * crypto_transfer_hash_request_to_engine - transfer one ahash_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_request_to_engine(engine, &req->base);

  }

  EXPORT_SYMBOL_GPL(crypto_transfer_hash_request_to_engine);

  
  /**

   * crypto_transfer_skcipher_request_to_engine - transfer one skcipher_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_skcipher_request_to_engine(struct crypto_engine *engine,
  					       struct skcipher_request *req)
  {
  	return crypto_transfer_request_to_engine(engine, &req->base);
  }
  EXPORT_SYMBOL_GPL(crypto_transfer_skcipher_request_to_engine);
  
  /**
   * crypto_finalize_ablkcipher_request - finalize one ablkcipher_request if
   * the request is done

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

   * TODO: Remove this function when skcipher conversion is finished

   */

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

  {

  	return crypto_finalize_request(engine, &req->base, err);
  }
  EXPORT_SYMBOL_GPL(crypto_finalize_ablkcipher_request);

  /**
   * crypto_finalize_aead_request - finalize one aead_request if
   * the request is done
   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */
  void crypto_finalize_aead_request(struct crypto_engine *engine,
  				  struct aead_request *req, int err)
  {
  	return crypto_finalize_request(engine, &req->base, err);
  }
  EXPORT_SYMBOL_GPL(crypto_finalize_aead_request);

  /**
   * crypto_finalize_akcipher_request - finalize one akcipher_request if
   * the request is done
   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */
  void crypto_finalize_akcipher_request(struct crypto_engine *engine,
  				      struct akcipher_request *req, int err)
  {
  	return crypto_finalize_request(engine, &req->base, err);

  }

  EXPORT_SYMBOL_GPL(crypto_finalize_akcipher_request);

  
  /**

   * crypto_finalize_hash_request - finalize one ahash_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)
  {

  	return crypto_finalize_request(engine, &req->base, err);

  }

  EXPORT_SYMBOL_GPL(crypto_finalize_hash_request);

  
  /**

   * crypto_finalize_skcipher_request - finalize one skcipher_request if
   * the request is done
   * @engine: the hardware engine
   * @req: the request need to be finalized
   * @err: error number
   */
  void crypto_finalize_skcipher_request(struct crypto_engine *engine,
  				      struct skcipher_request *req, int err)
  {
  	return crypto_finalize_request(engine, &req->base, err);
  }
  EXPORT_SYMBOL_GPL(crypto_finalize_skcipher_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)

  		dev_warn(engine->dev, "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->dev = dev;

  	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);

  	engine->kworker = kthread_create_worker(0, "%s", engine->name);
  	if (IS_ERR(engine->kworker)) {

  		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_destroy_worker(engine->kworker);

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