crypto: engine - Introduce the block request crypto engine framework

Now block cipher engines need to implement and maintain their own queue/thread
for processing requests, moreover currently helpers provided for only the queue
itself (in crypto_enqueue_request() and crypto_dequeue_request()) but they
don't help with the mechanics of driving the hardware (things like running the
request immediately, DMA map it or providing a thread to process the queue in)
even though a lot of that code really shouldn't vary that much from device to
device.

Thus this patch provides a mechanism for pushing requests to the hardware
as it becomes free that drivers could use. And this framework is patterned
on the SPI code and has worked out well there.
(https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/
 drivers/spi/spi.c?id=ffbbdd21329f3e15eeca6df2d4bc11c04d9d91c0)

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 359 insertions, 0 deletions

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 099f1f1..f6bfdda 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -217,6 +217,9 @@ config CRYPTO_GLUE_HELPER_X86
 	depends on X86
 	select CRYPTO_ALGAPI
 
+config CRYPTO_ENGINE
+	tristate
+
 comment "Authenticated Encryption with Associated Data"
 
 config CRYPTO_CCM
diff --git a/crypto/Makefile b/crypto/Makefile
index 059de1b..4f4ef7e 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -7,6 +7,7 @@ crypto-y := api.o cipher.o compress.o memneq.o
 
 obj-$(CONFIG_CRYPTO_WORKQUEUE) += crypto_wq.o
 
+obj-$(CONFIG_CRYPTO_ENGINE) += crypto_engine.o
 obj-$(CONFIG_CRYPTO_FIPS) += fips.o
 
 crypto_algapi-$(CONFIG_PROC_FS) += proc.o
diff --git a/crypto/crypto_engine.c b/crypto/crypto_engine.c
new file mode 100644
index 0000000..a55c82d
--- /dev/null
+++ b/crypto/crypto_engine.c
@@ -0,0 +1,355 @@
+/*
+ * 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 "internal.h"
+
+#define CRYPTO_ENGINE_MAX_QLEN 10
+
+void crypto_finalize_request(struct crypto_engine *engine,
+			     struct ablkcipher_request *req, int err);
+
+/**
+ * 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 ablkcipher_request *req;
+	unsigned long flags;
+	bool was_busy = false;
+	int ret;
+
+	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) {
+		queue_kthread_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) {
+			queue_kthread_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\n");
+
+		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;
+
+	req = ablkcipher_request_cast(async_req);
+
+	engine->cur_req = 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) {
+			pr_err("failed to prepare crypt hardware\n");
+			goto req_err;
+		}
+	}
+
+	if (engine->prepare_request) {
+		ret = engine->prepare_request(engine, engine->cur_req);
+		if (ret) {
+			pr_err("failed to prepare request: %d\n", ret);
+			goto req_err;
+		}
+		engine->cur_req_prepared = true;
+	}
+
+	ret = engine->crypt_one_request(engine, engine->cur_req);
+	if (ret) {
+		pr_err("failed to crypt one request from queue\n");
+		goto req_err;
+	}
+	return;
+
+req_err:
+	crypto_finalize_request(engine, engine->cur_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
+ */
+int crypto_transfer_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)
+		queue_kthread_work(&engine->kworker, &engine->pump_requests);
+
+	spin_unlock_irqrestore(&engine->queue_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_transfer_request);
+
+/**
+ * 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
+ */
+int crypto_transfer_request_to_engine(struct crypto_engine *engine,
+				      struct ablkcipher_request *req)
+{
+	return crypto_transfer_request(engine, req, true);
+}
+EXPORT_SYMBOL_GPL(crypto_transfer_request_to_engine);
+
+/**
+ * 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
+ */
+void crypto_finalize_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)
+		finalize_cur_req = true;
+	spin_unlock_irqrestore(&engine->queue_lock, flags);
+
+	if (finalize_cur_req) {
+		if (engine->cur_req_prepared && engine->unprepare_request) {
+			ret = engine->unprepare_request(engine, req);
+			if (ret)
+				pr_err("failed to unprepare request\n");
+		}
+
+		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);
+
+	queue_kthread_work(&engine->kworker, &engine->pump_requests);
+}
+EXPORT_SYMBOL_GPL(crypto_finalize_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);
+
+	queue_kthread_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 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\n");
+
+	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);
+
+	init_kthread_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\n");
+		return NULL;
+	}
+	init_kthread_work(&engine->pump_requests, crypto_pump_work);
+
+	if (engine->rt) {
+		dev_info(dev, "will run requests pump with realtime priority\n");
+		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;
+
+	flush_kthread_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");