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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c
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// SPDX-License-Identifier: GPL-2.0

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/*

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 * sun8i-ce-trng.c - hardware cryptographic offloader for

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 * Allwinner H3/A64/H5/H2+/H6/R40 SoC

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 *

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 * Copyright (C) 2015-2020 Corentin Labbe <[email protected]>

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 *

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 * This file handle the TRNG

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 *

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 * You could find a link for the datasheet in Documentation/arch/arm/sunxi.rst

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 */

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#include "sun8i-ce.h"

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#include <linux/dma-mapping.h>

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#include <linux/pm_runtime.h>

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#include <linux/hw_random.h>

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/*

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 * Note that according to the algorithm ID, 2 versions of the TRNG exists,

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 * The first present in H3/H5/R40/A64 and the second present in H6.

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 * This file adds support for both, but only the second is working

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 * reliabily according to rngtest.

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 **/

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static int sun8i_ce_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)

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{

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	struct sun8i_ce_dev *ce;

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	dma_addr_t dma_dst;

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	int err = 0;

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	int flow = 3;

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	unsigned int todo;

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	struct sun8i_ce_flow *chan;

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	struct ce_task *cet;

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	u32 common;

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	void *d;

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	ce = container_of(rng, struct sun8i_ce_dev, trng);

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	/* round the data length to a multiple of 32*/

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	todo = max + 32;

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	todo -= todo % 32;

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	d = kzalloc(todo, GFP_KERNEL | GFP_DMA);

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	if (!d)

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		return -ENOMEM;

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#ifdef CONFIG_CRYPTO_DEV_SUN8I_CE_DEBUG

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	ce->hwrng_stat_req++;

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	ce->hwrng_stat_bytes += todo;

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#endif

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	dma_dst = dma_map_single(ce->dev, d, todo, DMA_FROM_DEVICE);

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	if (dma_mapping_error(ce->dev, dma_dst)) {

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		dev_err(ce->dev, "Cannot DMA MAP DST\n");

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		err = -EFAULT;

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		goto err_dst;

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	}

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	err = pm_runtime_resume_and_get(ce->dev);

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	if (err < 0)

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		goto err_pm;

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	mutex_lock(&ce->rnglock);

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	chan = &ce->chanlist[flow];

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	cet = &chan->tl[0];

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	memset(cet, 0, sizeof(struct ce_task));

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	cet->t_id = cpu_to_le32(flow);

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	common = ce->variant->trng | CE_COMM_INT;

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	cet->t_common_ctl = cpu_to_le32(common);

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	/* recent CE (H6) need length in bytes, in word otherwise */

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	if (ce->variant->trng_t_dlen_in_bytes)

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		cet->t_dlen = cpu_to_le32(todo);

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	else

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		cet->t_dlen = cpu_to_le32(todo / 4);

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	cet->t_sym_ctl = 0;

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	cet->t_asym_ctl = 0;

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	cet->t_dst[0].addr = desc_addr_val_le32(ce, dma_dst);

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	cet->t_dst[0].len = cpu_to_le32(todo / 4);

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	ce->chanlist[flow].timeout = todo;

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	err = sun8i_ce_run_task(ce, 3, "TRNG");

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	mutex_unlock(&ce->rnglock);

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	pm_runtime_put(ce->dev);

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err_pm:

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	dma_unmap_single(ce->dev, dma_dst, todo, DMA_FROM_DEVICE);

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	if (!err) {

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		memcpy(data, d, max);

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		err = max;

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	}

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err_dst:

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	kfree_sensitive(d);

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	return err;

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}

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int sun8i_ce_hwrng_register(struct sun8i_ce_dev *ce)

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{

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	int ret;

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	if (ce->variant->trng == CE_ID_NOTSUPP) {

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		dev_info(ce->dev, "TRNG not supported\n");

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		return 0;

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	}

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	ce->trng.name = "sun8i Crypto Engine TRNG";

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	ce->trng.read = sun8i_ce_trng_read;

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	ret = hwrng_register(&ce->trng);

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	if (ret)

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		dev_err(ce->dev, "Fail to register the TRNG\n");

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	return ret;

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}

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void sun8i_ce_hwrng_unregister(struct sun8i_ce_dev *ce)

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{

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	if (ce->variant->trng == CE_ID_NOTSUPP)

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		return;

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	hwrng_unregister(&ce->trng);

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}

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