drivers/crypto/mxs-dcp.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Freescale i.MX23/i.MX28 Data Co-Processor driver
 *
 * Copyright (C) 2013 Marek Vasut <marex@denx.de>
 */

#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/stmp_device.h>
#include <linux/clk.h>
#include <soc/fsl/dcp.h>

#include <crypto/aes.h>
#include <crypto/sha1.h>
#include <crypto/sha2.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>

#define DCP_MAX_CHANS	4
#define DCP_BUF_SZ	PAGE_SIZE
#define DCP_SHA_PAY_SZ  64

#define DCP_ALIGNMENT	64

/*
 * Null hashes to align with hw behavior on imx6sl and ull
 * these are flipped for consistency with hw output
 */
static const uint8_t sha1_null_hash[] =
	"\x09\x07\xd8\xaf\x90\x18\x60\x95\xef\xbf"
	"\x55\x32\x0d\x4b\x6b\x5e\xee\xa3\x39\xda";

static const uint8_t sha256_null_hash[] =
	"\x55\xb8\x52\x78\x1b\x99\x95\xa4"
	"\x4c\x93\x9b\x64\xe4\x41\xae\x27"
	"\x24\xb9\x6f\x99\xc8\xf4\xfb\x9a"
	"\x14\x1c\xfc\x98\x42\xc4\xb0\xe3";

/* DCP DMA descriptor. */
struct dcp_dma_desc {
	uint32_t	next_cmd_addr;
	uint32_t	control0;
	uint32_t	control1;
	uint32_t	source;
	uint32_t	destination;
	uint32_t	size;
	uint32_t	payload;
	uint32_t	status;
};

/* Coherent aligned block for bounce buffering. */
struct dcp_coherent_block {
	uint8_t			aes_in_buf[DCP_BUF_SZ];
	uint8_t			aes_out_buf[DCP_BUF_SZ];
	uint8_t			sha_in_buf[DCP_BUF_SZ];
	uint8_t			sha_out_buf[DCP_SHA_PAY_SZ];

	uint8_t			aes_key[2 * AES_KEYSIZE_128];

	struct dcp_dma_desc	desc[DCP_MAX_CHANS];
};

struct dcp {
	struct device			*dev;
	void __iomem			*base;

	uint32_t			caps;

	struct dcp_coherent_block	*coh;

	struct completion		completion[DCP_MAX_CHANS];
	spinlock_t			lock[DCP_MAX_CHANS];
	struct task_struct		*thread[DCP_MAX_CHANS];
	struct crypto_queue		queue[DCP_MAX_CHANS];
	struct clk			*dcp_clk;
};

enum dcp_chan {
	DCP_CHAN_HASH_SHA	= 0,
	DCP_CHAN_CRYPTO		= 2,
};

struct dcp_async_ctx {
	/* Common context */
	enum dcp_chan	chan;
	uint32_t	fill;

	/* SHA Hash-specific context */
	struct mutex			mutex;
	uint32_t			alg;
	unsigned int			hot:1;

	/* Crypto-specific context */
	struct crypto_skcipher		*fallback;
	unsigned int			key_len;
	uint8_t				key[AES_KEYSIZE_128];
	bool				key_referenced;
};

struct dcp_aes_req_ctx {
	unsigned int	enc:1;
	unsigned int	ecb:1;
	struct skcipher_request fallback_req;	// keep at the end
};

struct dcp_sha_req_ctx {
	unsigned int	init:1;
	unsigned int	fini:1;
};

struct dcp_export_state {
	struct dcp_sha_req_ctx req_ctx;
	struct dcp_async_ctx async_ctx;
};

/*
 * There can even be only one instance of the MXS DCP due to the
 * design of Linux Crypto API.
 */
static struct dcp *global_sdcp;

/* DCP register layout. */
#define MXS_DCP_CTRL				0x00
#define MXS_DCP_CTRL_GATHER_RESIDUAL_WRITES	(1 << 23)
#define MXS_DCP_CTRL_ENABLE_CONTEXT_CACHING	(1 << 22)

#define MXS_DCP_STAT				0x10
#define MXS_DCP_STAT_CLR			0x18
#define MXS_DCP_STAT_IRQ_MASK			0xf

#define MXS_DCP_CHANNELCTRL			0x20
#define MXS_DCP_CHANNELCTRL_ENABLE_CHANNEL_MASK	0xff

#define MXS_DCP_CAPABILITY1			0x40
#define MXS_DCP_CAPABILITY1_SHA256		(4 << 16)
#define MXS_DCP_CAPABILITY1_SHA1		(1 << 16)
#define MXS_DCP_CAPABILITY1_AES128		(1 << 0)

#define MXS_DCP_CONTEXT				0x50

#define MXS_DCP_CH_N_CMDPTR(n)			(0x100 + ((n) * 0x40))

#define MXS_DCP_CH_N_SEMA(n)			(0x110 + ((n) * 0x40))

#define MXS_DCP_CH_N_STAT(n)			(0x120 + ((n) * 0x40))
#define MXS_DCP_CH_N_STAT_CLR(n)		(0x128 + ((n) * 0x40))

/* DMA descriptor bits. */
#define MXS_DCP_CONTROL0_HASH_TERM		(1 << 13)
#define MXS_DCP_CONTROL0_HASH_INIT		(1 << 12)
#define MXS_DCP_CONTROL0_PAYLOAD_KEY		(1 << 11)
#define MXS_DCP_CONTROL0_OTP_KEY		(1 << 10)
#define MXS_DCP_CONTROL0_CIPHER_ENCRYPT		(1 << 8)
#define MXS_DCP_CONTROL0_CIPHER_INIT		(1 << 9)
#define MXS_DCP_CONTROL0_ENABLE_HASH		(1 << 6)
#define MXS_DCP_CONTROL0_ENABLE_CIPHER		(1 << 5)
#define MXS_DCP_CONTROL0_DECR_SEMAPHORE		(1 << 1)
#define MXS_DCP_CONTROL0_INTERRUPT		(1 << 0)

#define MXS_DCP_CONTROL1_HASH_SELECT_SHA256	(2 << 16)
#define MXS_DCP_CONTROL1_HASH_SELECT_SHA1	(0 << 16)
#define MXS_DCP_CONTROL1_CIPHER_MODE_CBC	(1 << 4)
#define MXS_DCP_CONTROL1_CIPHER_MODE_ECB	(0 << 4)
#define MXS_DCP_CONTROL1_CIPHER_SELECT_AES128	(0 << 0)

#define MXS_DCP_CONTROL1_KEY_SELECT_SHIFT	8

static int mxs_dcp_start_dma(struct dcp_async_ctx *actx)
{
	int dma_err;
	struct dcp *sdcp = global_sdcp;
	const int chan = actx->chan;
	uint32_t stat;
	unsigned long ret;
	struct dcp_dma_desc *desc = &sdcp->coh->desc[actx->chan];
	dma_addr_t desc_phys = dma_map_single(sdcp->dev, desc, sizeof(*desc),
					      DMA_TO_DEVICE);

	dma_err = dma_mapping_error(sdcp->dev, desc_phys);
	if (dma_err)
		return dma_err;

	reinit_completion(&sdcp->completion[chan]);

	/* Clear status register. */
	writel(0xffffffff, sdcp->base + MXS_DCP_CH_N_STAT_CLR(chan));

	/* Load the DMA descriptor. */
	writel(desc_phys, sdcp->base + MXS_DCP_CH_N_CMDPTR(chan));

	/* Increment the semaphore to start the DMA transfer. */
	writel(1, sdcp->base + MXS_DCP_CH_N_SEMA(chan));

	ret = wait_for_completion_timeout(&sdcp->completion[chan],
					  msecs_to_jiffies(1000));
	if (!ret) {
		dev_err(sdcp->dev, "Channel %i timeout (DCP_STAT=0x%08x)\n",
			chan, readl(sdcp->base + MXS_DCP_STAT));
		return -ETIMEDOUT;
	}

	stat = readl(sdcp->base + MXS_DCP_CH_N_STAT(chan));
	if (stat & 0xff) {
		dev_err(sdcp->dev, "Channel %i error (CH_STAT=0x%08x)\n",
			chan, stat);
		return -EINVAL;
	}

	dma_unmap_single(sdcp->dev, desc_phys, sizeof(*desc), DMA_TO_DEVICE);

	return 0;
}

/*
 * Encryption (AES128)
 */
static int mxs_dcp_run_aes(struct dcp_async_ctx *actx,
			   struct skcipher_request *req, int init)
{
	dma_addr_t key_phys = 0;
	dma_addr_t src_phys, dst_phys;
	struct dcp *sdcp = global_sdcp;
	struct dcp_dma_desc *desc = &sdcp->coh->desc[actx->chan];
	struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req);
	bool key_referenced = actx->key_referenced;
	int ret;

	if (!key_referenced) {
		key_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_key,
					  2 * AES_KEYSIZE_128, DMA_TO_DEVICE);
		ret = dma_mapping_error(sdcp->dev, key_phys);
		if (ret)
			return ret;
	}

	src_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_in_buf,
				  DCP_BUF_SZ, DMA_TO_DEVICE);
	ret = dma_mapping_error(sdcp->dev, src_phys);
	if (ret)
		goto err_src;

	dst_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_out_buf,
				  DCP_BUF_SZ, DMA_FROM_DEVICE);
	ret = dma_mapping_error(sdcp->dev, dst_phys);
	if (ret)
		goto err_dst;

	if (actx->fill % AES_BLOCK_SIZE) {
		dev_err(sdcp->dev, "Invalid block size!\n");
		ret = -EINVAL;
		goto aes_done_run;
	}

	/* Fill in the DMA descriptor. */
	desc->control0 = MXS_DCP_CONTROL0_DECR_SEMAPHORE |
		    MXS_DCP_CONTROL0_INTERRUPT |
		    MXS_DCP_CONTROL0_ENABLE_CIPHER;

	if (key_referenced)
		/* Set OTP key bit to select the key via KEY_SELECT. */
		desc->control0 |= MXS_DCP_CONTROL0_OTP_KEY;
	else
		/* Payload contains the key. */
		desc->control0 |= MXS_DCP_CONTROL0_PAYLOAD_KEY;

	if (rctx->enc)
		desc->control0 |= MXS_DCP_CONTROL0_CIPHER_ENCRYPT;
	if (init)
		desc->control0 |= MXS_DCP_CONTROL0_CIPHER_INIT;

	desc->control1 = MXS_DCP_CONTROL1_CIPHER_SELECT_AES128;

	if (rctx->ecb)
		desc->control1 |= MXS_DCP_CONTROL1_CIPHER_MODE_ECB;
	else
		desc->control1 |= MXS_DCP_CONTROL1_CIPHER_MODE_CBC;

	if (key_referenced)
		desc->control1 |= sdcp->coh->aes_key[0] << MXS_DCP_CONTROL1_KEY_SELECT_SHIFT;

	desc->next_cmd_addr = 0;
	desc->source = src_phys;
	desc->destination = dst_phys;
	desc->size = actx->fill;
	desc->payload = key_phys;
	desc->status = 0;

	ret = mxs_dcp_start_dma(actx);

aes_done_run:
	dma_unmap_single(sdcp->dev, dst_phys, DCP_BUF_SZ, DMA_FROM_DEVICE);
err_dst:
	dma_unmap_single(sdcp->dev, src_phys, DCP_BUF_SZ, DMA_TO_DEVICE);
err_src:
	if (!key_referenced)
		dma_unmap_single(sdcp->dev, key_phys, 2 * AES_KEYSIZE_128,
				 DMA_TO_DEVICE);
	return ret;
}

static int mxs_dcp_aes_block_crypt(struct crypto_async_request *arq)
{
	struct dcp *sdcp = global_sdcp;

	struct skcipher_request *req = skcipher_request_cast(arq);
	struct dcp_async_ctx *actx = crypto_tfm_ctx(arq->tfm);
	struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req);

	struct scatterlist *dst = req->dst;
	struct scatterlist *src = req->src;
	int dst_nents = sg_nents(dst);

	const int out_off = DCP_BUF_SZ;
	uint8_t *in_buf = sdcp->coh->aes_in_buf;
	uint8_t *out_buf = sdcp->coh->aes_out_buf;

	uint32_t dst_off = 0;
	uint8_t *src_buf = NULL;
	uint32_t last_out_len = 0;

	uint8_t *key = sdcp->coh->aes_key;

	int ret = 0;
	unsigned int i, len, clen, tlen = 0;
	int init = 0;
	bool limit_hit = false;

	actx->fill = 0;

	/* Copy the key from the temporary location. */
	memcpy(key, actx->key, actx->key_len);

	if (!rctx->ecb) {
		/* Copy the CBC IV just past the key. */
		memcpy(key + AES_KEYSIZE_128, req->iv, AES_KEYSIZE_128);
		/* CBC needs the INIT set. */
		init = 1;
	} else {
		memset(key + AES_KEYSIZE_128, 0, AES_KEYSIZE_128);
	}

	for_each_sg(req->src, src, sg_nents(req->src), i) {
		src_buf = sg_virt(src);
		len = sg_dma_len(src);
		tlen += len;
		limit_hit = tlen > req->cryptlen;

		if (limit_hit)
			len = req->cryptlen - (tlen - len);

		do {
			if (actx->fill + len > out_off)
				clen = out_off - actx->fill;
			else
				clen = len;

			memcpy(in_buf + actx->fill, src_buf, clen);
			len -= clen;
			src_buf += clen;
			actx->fill += clen;

			/*
			 * If we filled the buffer or this is the last SG,
			 * submit the buffer.
			 */
			if (actx->fill == out_off || sg_is_last(src) ||
			    limit_hit) {
				ret = mxs_dcp_run_aes(actx, req, init);
				if (ret)
					return ret;
				init = 0;

				sg_pcopy_from_buffer(dst, dst_nents, out_buf,
						     actx->fill, dst_off);
				dst_off += actx->fill;
				last_out_len = actx->fill;
				actx->fill = 0;
			}
		} while (len);

		if (limit_hit)
			break;
	}

	/* Copy the IV for CBC for chaining */
	if (!rctx->ecb) {
		if (rctx->enc)
			memcpy(req->iv, out_buf+(last_out_len-AES_BLOCK_SIZE),
				AES_BLOCK_SIZE);
		else
			memcpy(req->iv, in_buf+(last_out_len-AES_BLOCK_SIZE),
				AES_BLOCK_SIZE);
	}

	return ret;
}

static int dcp_chan_thread_aes(void *data)
{
	struct dcp *sdcp = global_sdcp;
	const int chan = DCP_CHAN_CRYPTO;

	struct crypto_async_request *backlog;
	struct crypto_async_request *arq;

	int ret;

	while (!kthread_should_stop()) {
		set_current_state(TASK_INTERRUPTIBLE);

		spin_lock(&sdcp->lock[chan]);
		backlog = crypto_get_backlog(&sdcp->queue[chan]);
		arq = crypto_dequeue_request(&sdcp->queue[chan]);
		spin_unlock(&sdcp->lock[chan]);

		if (!backlog && !arq) {
			schedule();
			continue;
		}

		set_current_state(TASK_RUNNING);

		if (backlog)
			crypto_request_complete(backlog, -EINPROGRESS);

		if (arq) {
			ret = mxs_dcp_aes_block_crypt(arq);
			crypto_request_complete(arq, ret);
		}
	}

	return 0;
}

static int mxs_dcp_block_fallback(struct skcipher_request *req, int enc)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req);
	struct dcp_async_ctx *ctx = crypto_skcipher_ctx(tfm);
	int ret;

	skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback);
	skcipher_request_set_callback(&rctx->fallback_req, req->base.flags,
				      req->base.complete, req->base.data);
	skcipher_request_set_crypt(&rctx->fallback_req, req->src, req->dst,
				   req->cryptlen, req->iv);

	if (enc)
		ret = crypto_skcipher_encrypt(&rctx->fallback_req);
	else
		ret = crypto_skcipher_decrypt(&rctx->fallback_req);

	return ret;
}

static int mxs_dcp_aes_enqueue(struct skcipher_request *req, int enc, int ecb)
{
	struct dcp *sdcp = global_sdcp;
	struct crypto_async_request *arq = &req->base;
	struct dcp_async_ctx *actx = crypto_tfm_ctx(arq->tfm);
	struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req);
	int ret;

	if (unlikely(actx->key_len != AES_KEYSIZE_128 && !actx->key_referenced))
		return mxs_dcp_block_fallback(req, enc);

	rctx->enc = enc;
	rctx->ecb = ecb;
	actx->chan = DCP_CHAN_CRYPTO;

	spin_lock(&sdcp->lock[actx->chan]);
	ret = crypto_enqueue_request(&sdcp->queue[actx->chan], &req->base);
	spin_unlock(&sdcp->lock[actx->chan]);

	wake_up_process(sdcp->thread[actx->chan]);

	return ret;
}

static int mxs_dcp_aes_ecb_decrypt(struct skcipher_request *req)
{
	return mxs_dcp_aes_enqueue(req, 0, 1);
}

static int mxs_dcp_aes_ecb_encrypt(struct skcipher_request *req)
{
	return mxs_dcp_aes_enqueue(req, 1, 1);
}

static int mxs_dcp_aes_cbc_decrypt(struct skcipher_request *req)
{
	return mxs_dcp_aes_enqueue(req, 0, 0);
}

static int mxs_dcp_aes_cbc_encrypt(struct skcipher_request *req)
{
	return mxs_dcp_aes_enqueue(req, 1, 0);
}

static int mxs_dcp_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
			      unsigned int len)
{
	struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm);

	/*
	 * AES 128 is supposed by the hardware, store key into temporary
	 * buffer and exit. We must use the temporary buffer here, since
	 * there can still be an operation in progress.
	 */
	actx->key_len = len;
	actx->key_referenced = false;
	if (len == AES_KEYSIZE_128) {
		memcpy(actx->key, key, len);
		return 0;
	}

	/*
	 * If the requested AES key size is not supported by the hardware,
	 * but is supported by in-kernel software implementation, we use
	 * software fallback.
	 */
	crypto_skcipher_clear_flags(actx->fallback, CRYPTO_TFM_REQ_MASK);
	crypto_skcipher_set_flags(actx->fallback,
				  tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
	return crypto_skcipher_setkey(actx->fallback, key, len);
}

static int mxs_dcp_aes_setrefkey(struct crypto_skcipher *tfm, const u8 *key,
				 unsigned int len)
{
	struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm);

	if (len != DCP_PAES_KEYSIZE)
		return -EINVAL;

	switch (key[0]) {
	case DCP_PAES_KEY_SLOT0:
	case DCP_PAES_KEY_SLOT1:
	case DCP_PAES_KEY_SLOT2:
	case DCP_PAES_KEY_SLOT3:
	case DCP_PAES_KEY_UNIQUE:
	case DCP_PAES_KEY_OTP:
		memcpy(actx->key, key, len);
		actx->key_len = len;
		actx->key_referenced = true;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int mxs_dcp_aes_fallback_init_tfm(struct crypto_skcipher *tfm)
{
	const char *name = crypto_tfm_alg_name(crypto_skcipher_tfm(tfm));
	struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm);
	struct crypto_skcipher *blk;

	blk = crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
	if (IS_ERR(blk))
		return PTR_ERR(blk);

	actx->fallback = blk;
	crypto_skcipher_set_reqsize(tfm, sizeof(struct dcp_aes_req_ctx) +
					 crypto_skcipher_reqsize(blk));
	return 0;
}

static void mxs_dcp_aes_fallback_exit_tfm(struct crypto_skcipher *tfm)
{
	struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm);

	crypto_free_skcipher(actx->fallback);
}

static int mxs_dcp_paes_init_tfm(struct crypto_skcipher *tfm)
{
	crypto_skcipher_set_reqsize(tfm, sizeof(struct dcp_aes_req_ctx));

	return 0;
}

/*
 * Hashing (SHA1/SHA256)
 */
static int mxs_dcp_run_sha(struct ahash_request *req)
{
	struct dcp *sdcp = global_sdcp;
	int ret;

	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);
	struct dcp_sha_req_ctx *rctx = ahash_request_ctx(req);
	struct dcp_dma_desc *desc = &sdcp->coh->desc[actx->chan];

	dma_addr_t digest_phys = 0;
	dma_addr_t buf_phys = dma_map_single(sdcp->dev, sdcp->coh->sha_in_buf,
					     DCP_BUF_SZ, DMA_TO_DEVICE);

	ret = dma_mapping_error(sdcp->dev, buf_phys);
	if (ret)
		return ret;

	/* Fill in the DMA descriptor. */
	desc->control0 = MXS_DCP_CONTROL0_DECR_SEMAPHORE |
		    MXS_DCP_CONTROL0_INTERRUPT |
		    MXS_DCP_CONTROL0_ENABLE_HASH;
	if (rctx->init)
		desc->control0 |= MXS_DCP_CONTROL0_HASH_INIT;

	desc->control1 = actx->alg;
	desc->next_cmd_addr = 0;
	desc->source = buf_phys;
	desc->destination = 0;
	desc->size = actx->fill;
	desc->payload = 0;
	desc->status = 0;

	/*
	 * Align driver with hw behavior when generating null hashes
	 */
	if (rctx->init && rctx->fini && desc->size == 0) {
		struct hash_alg_common *halg = crypto_hash_alg_common(tfm);
		const uint8_t *sha_buf =
			(actx->alg == MXS_DCP_CONTROL1_HASH_SELECT_SHA1) ?
			sha1_null_hash : sha256_null_hash;
		memcpy(sdcp->coh->sha_out_buf, sha_buf, halg->digestsize);
		ret = 0;
		goto done_run;
	}

	/* Set HASH_TERM bit for last transfer block. */
	if (rctx->fini) {
		digest_phys = dma_map_single(sdcp->dev, sdcp->coh->sha_out_buf,
					     DCP_SHA_PAY_SZ, DMA_FROM_DEVICE);
		ret = dma_mapping_error(sdcp->dev, digest_phys);
		if (ret)
			goto done_run;

		desc->control0 |= MXS_DCP_CONTROL0_HASH_TERM;
		desc->payload = digest_phys;
	}

	ret = mxs_dcp_start_dma(actx);

	if (rctx->fini)
		dma_unmap_single(sdcp->dev, digest_phys, DCP_SHA_PAY_SZ,
				 DMA_FROM_DEVICE);

done_run:
	dma_unmap_single(sdcp->dev, buf_phys, DCP_BUF_SZ, DMA_TO_DEVICE);

	return ret;
}

static int dcp_sha_req_to_buf(struct crypto_async_request *arq)
{
	struct dcp *sdcp = global_sdcp;

	struct ahash_request *req = ahash_request_cast(arq);
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);
	struct dcp_sha_req_ctx *rctx = ahash_request_ctx(req);
	struct hash_alg_common *halg = crypto_hash_alg_common(tfm);

	uint8_t *in_buf = sdcp->coh->sha_in_buf;
	uint8_t *out_buf = sdcp->coh->sha_out_buf;

	struct scatterlist *src;

	unsigned int i, len, clen, oft = 0;
	int ret;

	int fin = rctx->fini;
	if (fin)
		rctx->fini = 0;

	src = req->src;
	len = req->nbytes;

	while (len) {
		if (actx->fill + len > DCP_BUF_SZ)
			clen = DCP_BUF_SZ - actx->fill;
		else
			clen = len;

		scatterwalk_map_and_copy(in_buf + actx->fill, src, oft, clen,
					 0);

		len -= clen;
		oft += clen;
		actx->fill += clen;

		/*
		 * If we filled the buffer and still have some
		 * more data, submit the buffer.
		 */
		if (len && actx->fill == DCP_BUF_SZ) {
			ret = mxs_dcp_run_sha(req);
			if (ret)
				return ret;
			actx->fill = 0;
			rctx->init = 0;
		}
	}

	if (fin) {
		rctx->fini = 1;

		/* Submit whatever is left. */
		if (!req->result)
			return -EINVAL;

		ret = mxs_dcp_run_sha(req);
		if (ret)
			return ret;

		actx->fill = 0;

		/* For some reason the result is flipped */
		for (i = 0; i < halg->digestsize; i++)
			req->result[i] = out_buf[halg->digestsize - i - 1];
	}

	return 0;
}

static int dcp_chan_thread_sha(void *data)
{
	struct dcp *sdcp = global_sdcp;
	const int chan = DCP_CHAN_HASH_SHA;

	struct crypto_async_request *backlog;
	struct crypto_async_request *arq;
	int ret;

	while (!kthread_should_stop()) {
		set_current_state(TASK_INTERRUPTIBLE);

		spin_lock(&sdcp->lock[chan]);
		backlog = crypto_get_backlog(&sdcp->queue[chan]);
		arq = crypto_dequeue_request(&sdcp->queue[chan]);
		spin_unlock(&sdcp->lock[chan]);

		if (!backlog && !arq) {
			schedule();
			continue;
		}

		set_current_state(TASK_RUNNING);

		if (backlog)
			crypto_request_complete(backlog, -EINPROGRESS);

		if (arq) {
			ret = dcp_sha_req_to_buf(arq);
			crypto_request_complete(arq, ret);
		}
	}

	return 0;
}

static int dcp_sha_init(struct ahash_request *req)
{
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);

	struct hash_alg_common *halg = crypto_hash_alg_common(tfm);

	/*
	 * Start hashing session. The code below only inits the
	 * hashing session context, nothing more.
	 */
	memset(actx, 0, sizeof(*actx));

	if (strcmp(halg->base.cra_name, "sha1") == 0)
		actx->alg = MXS_DCP_CONTROL1_HASH_SELECT_SHA1;
	else
		actx->alg = MXS_DCP_CONTROL1_HASH_SELECT_SHA256;

	actx->fill = 0;
	actx->hot = 0;
	actx->chan = DCP_CHAN_HASH_SHA;

	mutex_init(&actx->mutex);

	return 0;
}

static int dcp_sha_update_fx(struct ahash_request *req, int fini)
{
	struct dcp *sdcp = global_sdcp;

	struct dcp_sha_req_ctx *rctx = ahash_request_ctx(req);
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);

	int ret;

	/*
	 * Ignore requests that have no data in them and are not
	 * the trailing requests in the stream of requests.
	 */
	if (!req->nbytes && !fini)
		return 0;

	mutex_lock(&actx->mutex);

	rctx->fini = fini;

	if (!actx->hot) {
		actx->hot = 1;
		rctx->init = 1;
	}

	spin_lock(&sdcp->lock[actx->chan]);
	ret = crypto_enqueue_request(&sdcp->queue[actx->chan], &req->base);
	spin_unlock(&sdcp->lock[actx->chan]);

	wake_up_process(sdcp->thread[actx->chan]);
	mutex_unlock(&actx->mutex);

	return ret;
}

static int dcp_sha_update(struct ahash_request *req)
{
	return dcp_sha_update_fx(req, 0);
}

static int dcp_sha_final(struct ahash_request *req)
{
	ahash_request_set_crypt(req, NULL, req->result, 0);
	req->nbytes = 0;
	return dcp_sha_update_fx(req, 1);
}

static int dcp_sha_finup(struct ahash_request *req)
{
	return dcp_sha_update_fx(req, 1);
}

static int dcp_sha_digest(struct ahash_request *req)
{
	int ret;

	ret = dcp_sha_init(req);
	if (ret)
		return ret;

	return dcp_sha_finup(req);
}

static int dcp_sha_import(struct ahash_request *req, const void *in)
{
	struct dcp_sha_req_ctx *rctx = ahash_request_ctx(req);
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);
	const struct dcp_export_state *export = in;

	memset(rctx, 0, sizeof(struct dcp_sha_req_ctx));
	memset(actx, 0, sizeof(struct dcp_async_ctx));
	memcpy(rctx, &export->req_ctx, sizeof(struct dcp_sha_req_ctx));
	memcpy(actx, &export->async_ctx, sizeof(struct dcp_async_ctx));

	return 0;
}

static int dcp_sha_export(struct ahash_request *req, void *out)
{
	struct dcp_sha_req_ctx *rctx_state = ahash_request_ctx(req);
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct dcp_async_ctx *actx_state = crypto_ahash_ctx(tfm);
	struct dcp_export_state *export = out;

	memcpy(&export->req_ctx, rctx_state, sizeof(struct dcp_sha_req_ctx));
	memcpy(&export->async_ctx, actx_state, sizeof(struct dcp_async_ctx));

	return 0;
}

static int dcp_sha_cra_init(struct crypto_tfm *tfm)
{
	crypto_ahash_set_reqsize(__crypto_ahash_cast(tfm),
				 sizeof(struct dcp_sha_req_ctx));
	return 0;
}

static void dcp_sha_cra_exit(struct crypto_tfm *tfm)
{
}

/* AES 128 ECB and AES 128 CBC */
static struct skcipher_alg dcp_aes_algs[] = {
	{
		.base.cra_name		= "ecb(aes)",
		.base.cra_driver_name	= "ecb-aes-dcp",
		.base.cra_priority	= 400,
		.base.cra_alignmask	= 15,
		.base.cra_flags		= CRYPTO_ALG_ASYNC |
					  CRYPTO_ALG_NEED_FALLBACK,
		.base.cra_blocksize	= AES_BLOCK_SIZE,
		.base.cra_ctxsize	= sizeof(struct dcp_async_ctx),
		.base.cra_module	= THIS_MODULE,

		.min_keysize		= AES_MIN_KEY_SIZE,
		.max_keysize		= AES_MAX_KEY_SIZE,
		.setkey			= mxs_dcp_aes_setkey,
		.encrypt		= mxs_dcp_aes_ecb_encrypt,
		.decrypt		= mxs_dcp_aes_ecb_decrypt,
		.init			= mxs_dcp_aes_fallback_init_tfm,
		.exit			= mxs_dcp_aes_fallback_exit_tfm,
	}, {
		.base.cra_name		= "cbc(aes)",
		.base.cra_driver_name	= "cbc-aes-dcp",
		.base.cra_priority	= 400,
		.base.cra_alignmask	= 15,
		.base.cra_flags		= CRYPTO_ALG_ASYNC |
					  CRYPTO_ALG_NEED_FALLBACK,
		.base.cra_blocksize	= AES_BLOCK_SIZE,
		.base.cra_ctxsize	= sizeof(struct dcp_async_ctx),
		.base.cra_module	= THIS_MODULE,

		.min_keysize		= AES_MIN_KEY_SIZE,
		.max_keysize		= AES_MAX_KEY_SIZE,
		.setkey			= mxs_dcp_aes_setkey,
		.encrypt		= mxs_dcp_aes_cbc_encrypt,
		.decrypt		= mxs_dcp_aes_cbc_decrypt,
		.ivsize			= AES_BLOCK_SIZE,
		.init			= mxs_dcp_aes_fallback_init_tfm,
		.exit			= mxs_dcp_aes_fallback_exit_tfm,
	}, {
		.base.cra_name		= "ecb(paes)",
		.base.cra_driver_name	= "ecb-paes-dcp",
		.base.cra_priority	= 401,
		.base.cra_alignmask	= 15,
		.base.cra_flags		= CRYPTO_ALG_ASYNC | CRYPTO_ALG_INTERNAL,
		.base.cra_blocksize	= AES_BLOCK_SIZE,
		.base.cra_ctxsize	= sizeof(struct dcp_async_ctx),
		.base.cra_module	= THIS_MODULE,

		.min_keysize		= DCP_PAES_KEYSIZE,
		.max_keysize		= DCP_PAES_KEYSIZE,
		.setkey			= mxs_dcp_aes_setrefkey,
		.encrypt		= mxs_dcp_aes_ecb_encrypt,
		.decrypt		= mxs_dcp_aes_ecb_decrypt,
		.init			= mxs_dcp_paes_init_tfm,
	}, {
		.base.cra_name		= "cbc(paes)",
		.base.cra_driver_name	= "cbc-paes-dcp",
		.base.cra_priority	= 401,
		.base.cra_alignmask	= 15,
		.base.cra_flags		= CRYPTO_ALG_ASYNC | CRYPTO_ALG_INTERNAL,
		.base.cra_blocksize	= AES_BLOCK_SIZE,
		.base.cra_ctxsize	= sizeof(struct dcp_async_ctx),
		.base.cra_module	= THIS_MODULE,

		.min_keysize		= DCP_PAES_KEYSIZE,
		.max_keysize		= DCP_PAES_KEYSIZE,
		.setkey			= mxs_dcp_aes_setrefkey,
		.encrypt		= mxs_dcp_aes_cbc_encrypt,
		.decrypt		= mxs_dcp_aes_cbc_decrypt,
		.ivsize			= AES_BLOCK_SIZE,
		.init			= mxs_dcp_paes_init_tfm,
	},
};

/* SHA1 */
static struct ahash_alg dcp_sha1_alg = {
	.init	= dcp_sha_init,
	.update	= dcp_sha_update,
	.final	= dcp_sha_final,
	.finup	= dcp_sha_finup,
	.digest	= dcp_sha_digest,
	.import = dcp_sha_import,
	.export = dcp_sha_export,
	.halg	= {
		.digestsize	= SHA1_DIGEST_SIZE,
		.statesize	= sizeof(struct dcp_export_state),
		.base		= {
			.cra_name		= "sha1",
			.cra_driver_name	= "sha1-dcp",
			.cra_priority		= 400,
			.cra_flags		= CRYPTO_ALG_ASYNC,
			.cra_blocksize		= SHA1_BLOCK_SIZE,
			.cra_ctxsize		= sizeof(struct dcp_async_ctx),
			.cra_module		= THIS_MODULE,
			.cra_init		= dcp_sha_cra_init,
			.cra_exit		= dcp_sha_cra_exit,
		},
	},
};

/* SHA256 */
static struct ahash_alg dcp_sha256_alg = {
	.init	= dcp_sha_init,
	.update	= dcp_sha_update,
	.final	= dcp_sha_final,
	.finup	= dcp_sha_finup,
	.digest	= dcp_sha_digest,
	.import = dcp_sha_import,
	.export = dcp_sha_export,
	.halg	= {
		.digestsize	= SHA256_DIGEST_SIZE,
		.statesize	= sizeof(struct dcp_export_state),
		.base		= {
			.cra_name		= "sha256",
			.cra_driver_name	= "sha256-dcp",
			.cra_priority		= 400,
			.cra_flags		= CRYPTO_ALG_ASYNC,
			.cra_blocksize		= SHA256_BLOCK_SIZE,
			.cra_ctxsize		= sizeof(struct dcp_async_ctx),
			.cra_module		= THIS_MODULE,
			.cra_init		= dcp_sha_cra_init,
			.cra_exit		= dcp_sha_cra_exit,
		},
	},
};

static irqreturn_t mxs_dcp_irq(int irq, void *context)
{
	struct dcp *sdcp = context;
	uint32_t stat;
	int i;

	stat = readl(sdcp->base + MXS_DCP_STAT);
	stat &= MXS_DCP_STAT_IRQ_MASK;
	if (!stat)
		return IRQ_NONE;

	/* Clear the interrupts. */
	writel(stat, sdcp->base + MXS_DCP_STAT_CLR);

	/* Complete the DMA requests that finished. */
	for (i = 0; i < DCP_MAX_CHANS; i++)
		if (stat & (1 << i))
			complete(&sdcp->completion[i]);

	return IRQ_HANDLED;
}

static int mxs_dcp_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct dcp *sdcp = NULL;
	int i, ret;
	int dcp_vmi_irq, dcp_irq;

	if (global_sdcp) {
		dev_err(dev, "Only one DCP instance allowed!\n");
		return -ENODEV;
	}

	dcp_vmi_irq = platform_get_irq(pdev, 0);
	if (dcp_vmi_irq < 0)
		return dcp_vmi_irq;

	dcp_irq = platform_get_irq(pdev, 1);
	if (dcp_irq < 0)
		return dcp_irq;

	sdcp = devm_kzalloc(dev, sizeof(*sdcp), GFP_KERNEL);
	if (!sdcp)
		return -ENOMEM;

	sdcp->dev = dev;
	sdcp->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(sdcp->base))
		return PTR_ERR(sdcp->base);


	ret = devm_request_irq(dev, dcp_vmi_irq, mxs_dcp_irq, 0,
			       "dcp-vmi-irq", sdcp);
	if (ret) {
		dev_err(dev, "Failed to claim DCP VMI IRQ!\n");
		return ret;
	}

	ret = devm_request_irq(dev, dcp_irq, mxs_dcp_irq, 0,
			       "dcp-irq", sdcp);
	if (ret) {
		dev_err(dev, "Failed to claim DCP IRQ!\n");
		return ret;
	}

	/* Allocate coherent helper block. */
	sdcp->coh = devm_kzalloc(dev, sizeof(*sdcp->coh) + DCP_ALIGNMENT,
				   GFP_KERNEL);
	if (!sdcp->coh)
		return -ENOMEM;

	/* Re-align the structure so it fits the DCP constraints. */
	sdcp->coh = PTR_ALIGN(sdcp->coh, DCP_ALIGNMENT);

	/* DCP clock is optional, only used on some SOCs */
	sdcp->dcp_clk = devm_clk_get_optional_enabled(dev, "dcp");
	if (IS_ERR(sdcp->dcp_clk))
		return PTR_ERR(sdcp->dcp_clk);

	/* Restart the DCP block. */
	ret = stmp_reset_block(sdcp->base);
	if (ret) {
		dev_err(dev, "Failed reset\n");
		return ret;
	}

	/* Initialize control register. */
	writel(MXS_DCP_CTRL_GATHER_RESIDUAL_WRITES |
	       MXS_DCP_CTRL_ENABLE_CONTEXT_CACHING | 0xf,
	       sdcp->base + MXS_DCP_CTRL);

	/* Enable all DCP DMA channels. */
	writel(MXS_DCP_CHANNELCTRL_ENABLE_CHANNEL_MASK,
	       sdcp->base + MXS_DCP_CHANNELCTRL);

	/*
	 * We do not enable context switching. Give the context buffer a
	 * pointer to an illegal address so if context switching is
	 * inadvertantly enabled, the DCP will return an error instead of
	 * trashing good memory. The DCP DMA cannot access ROM, so any ROM
	 * address will do.
	 */
	writel(0xffff0000, sdcp->base + MXS_DCP_CONTEXT);
	for (i = 0; i < DCP_MAX_CHANS; i++)
		writel(0xffffffff, sdcp->base + MXS_DCP_CH_N_STAT_CLR(i));
	writel(0xffffffff, sdcp->base + MXS_DCP_STAT_CLR);

	global_sdcp = sdcp;

	platform_set_drvdata(pdev, sdcp);

	for (i = 0; i < DCP_MAX_CHANS; i++) {
		spin_lock_init(&sdcp->lock[i]);
		init_completion(&sdcp->completion[i]);
		crypto_init_queue(&sdcp->queue[i], 50);
	}

	/* Create the SHA and AES handler threads. */
	sdcp->thread[DCP_CHAN_HASH_SHA] = kthread_run(dcp_chan_thread_sha,
						      NULL, "mxs_dcp_chan/sha");
	if (IS_ERR(sdcp->thread[DCP_CHAN_HASH_SHA])) {
		dev_err(dev, "Error starting SHA thread!\n");
		ret = PTR_ERR(sdcp->thread[DCP_CHAN_HASH_SHA]);
		return ret;
	}

	sdcp->thread[DCP_CHAN_CRYPTO] = kthread_run(dcp_chan_thread_aes,
						    NULL, "mxs_dcp_chan/aes");
	if (IS_ERR(sdcp->thread[DCP_CHAN_CRYPTO])) {
		dev_err(dev, "Error starting SHA thread!\n");
		ret = PTR_ERR(sdcp->thread[DCP_CHAN_CRYPTO]);
		goto err_destroy_sha_thread;
	}

	/* Register the various crypto algorithms. */
	sdcp->caps = readl(sdcp->base + MXS_DCP_CAPABILITY1);

	if (sdcp->caps & MXS_DCP_CAPABILITY1_AES128) {
		ret = crypto_register_skciphers(dcp_aes_algs,
						ARRAY_SIZE(dcp_aes_algs));
		if (ret) {
			/* Failed to register algorithm. */
			dev_err(dev, "Failed to register AES crypto!\n");
			goto err_destroy_aes_thread;
		}
	}

	if (sdcp->caps & MXS_DCP_CAPABILITY1_SHA1) {
		ret = crypto_register_ahash(&dcp_sha1_alg);
		if (ret) {
			dev_err(dev, "Failed to register %s hash!\n",
				dcp_sha1_alg.halg.base.cra_name);
			goto err_unregister_aes;
		}
	}

	if (sdcp->caps & MXS_DCP_CAPABILITY1_SHA256) {
		ret = crypto_register_ahash(&dcp_sha256_alg);
		if (ret) {
			dev_err(dev, "Failed to register %s hash!\n",
				dcp_sha256_alg.halg.base.cra_name);
			goto err_unregister_sha1;
		}
	}

	return 0;

err_unregister_sha1:
	if (sdcp->caps & MXS_DCP_CAPABILITY1_SHA1)
		crypto_unregister_ahash(&dcp_sha1_alg);

err_unregister_aes:
	if (sdcp->caps & MXS_DCP_CAPABILITY1_AES128)
		crypto_unregister_skciphers(dcp_aes_algs, ARRAY_SIZE(dcp_aes_algs));

err_destroy_aes_thread:
	kthread_stop(sdcp->thread[DCP_CHAN_CRYPTO]);

err_destroy_sha_thread:
	kthread_stop(sdcp->thread[DCP_CHAN_HASH_SHA]);

	return ret;
}

static void mxs_dcp_remove(struct platform_device *pdev)
{
	struct dcp *sdcp = platform_get_drvdata(pdev);

	if (sdcp->caps & MXS_DCP_CAPABILITY1_SHA256)
		crypto_unregister_ahash(&dcp_sha256_alg);

	if (sdcp->caps & MXS_DCP_CAPABILITY1_SHA1)
		crypto_unregister_ahash(&dcp_sha1_alg);

	if (sdcp->caps & MXS_DCP_CAPABILITY1_AES128)
		crypto_unregister_skciphers(dcp_aes_algs, ARRAY_SIZE(dcp_aes_algs));

	kthread_stop(sdcp->thread[DCP_CHAN_HASH_SHA]);
	kthread_stop(sdcp->thread[DCP_CHAN_CRYPTO]);

	platform_set_drvdata(pdev, NULL);

	global_sdcp = NULL;
}

static const struct of_device_id mxs_dcp_dt_ids[] = {
	{ .compatible = "fsl,imx23-dcp", .data = NULL, },
	{ .compatible = "fsl,imx28-dcp", .data = NULL, },
	{ /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, mxs_dcp_dt_ids);

static struct platform_driver mxs_dcp_driver = {
	.probe	= mxs_dcp_probe,
	.remove_new = mxs_dcp_remove,
	.driver	= {
		.name		= "mxs-dcp",
		.of_match_table	= mxs_dcp_dt_ids,
	},
};

module_platform_driver(mxs_dcp_driver);

MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
MODULE_DESCRIPTION("Freescale MXS DCP Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:mxs-dcp");