path: root/drivers/crypto/aspeed/aspeed-acry.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2021 Aspeed Technology Inc.
 */
#include <crypto/engine.h>
#include <crypto/internal/akcipher.h>
#include <crypto/internal/rsa.h>
#include <crypto/scatterwalk.h>
#include <linux/clk.h>
#include <linux/count_zeros.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/string.h>

#ifdef CONFIG_CRYPTO_DEV_ASPEED_DEBUG
#define ACRY_DBG(d, fmt, ...)	\
	dev_info((d)->dev, "%s() " fmt, __func__, ##__VA_ARGS__)
#else
#define ACRY_DBG(d, fmt, ...)	\
	dev_dbg((d)->dev, "%s() " fmt, __func__, ##__VA_ARGS__)
#endif

/*****************************
 *                           *
 * ACRY register definitions *
 *                           *
 * ***************************/
#define ASPEED_ACRY_TRIGGER		0x000	/* ACRY Engine Control: trigger */
#define ASPEED_ACRY_DMA_CMD		0x048	/* ACRY Engine Control: Command */
#define ASPEED_ACRY_DMA_SRC_BASE	0x04C	/* ACRY DRAM base address for DMA */
#define ASPEED_ACRY_DMA_LEN		0x050	/* ACRY Data Length of DMA */
#define ASPEED_ACRY_RSA_KEY_LEN		0x058	/* ACRY RSA Exp/Mod Key Length (Bits) */
#define ASPEED_ACRY_INT_MASK		0x3F8	/* ACRY Interrupt Mask */
#define ASPEED_ACRY_STATUS		0x3FC	/* ACRY Interrupt Status */

/* rsa trigger */
#define  ACRY_CMD_RSA_TRIGGER		BIT(0)
#define  ACRY_CMD_DMA_RSA_TRIGGER	BIT(1)

/* rsa dma cmd */
#define  ACRY_CMD_DMA_SRAM_MODE_RSA	(0x3 << 4)
#define  ACRY_CMD_DMEM_AHB		BIT(8)
#define  ACRY_CMD_DMA_SRAM_AHB_ENGINE	0

/* rsa key len */
#define  RSA_E_BITS_LEN(x)		((x) << 16)
#define  RSA_M_BITS_LEN(x)		(x)

/* acry isr */
#define  ACRY_RSA_ISR			BIT(1)

#define ASPEED_ACRY_BUFF_SIZE		0x1800	/* DMA buffer size */
#define ASPEED_ACRY_SRAM_MAX_LEN	2048	/* ACRY SRAM maximum length (Bytes) */
#define ASPEED_ACRY_RSA_MAX_KEY_LEN	512	/* ACRY RSA maximum key length (Bytes) */

#define CRYPTO_FLAGS_BUSY		BIT(1)
#define BYTES_PER_DWORD			4

/*****************************
 *                           *
 * AHBC register definitions *
 *                           *
 * ***************************/
#define AHBC_REGION_PROT		0x240
#define REGION_ACRYM			BIT(23)

#define ast_acry_write(acry, val, offset)	\
	writel((val), (acry)->regs + (offset))

#define ast_acry_read(acry, offset)		\
	readl((acry)->regs + (offset))

struct aspeed_acry_dev;

typedef int (*aspeed_acry_fn_t)(struct aspeed_acry_dev *);

struct aspeed_acry_dev {
	void __iomem			*regs;
	struct device			*dev;
	int				irq;
	struct clk			*clk;
	struct regmap			*ahbc;

	struct akcipher_request		*req;
	struct tasklet_struct		done_task;
	aspeed_acry_fn_t		resume;
	unsigned long			flags;

	/* ACRY output SRAM buffer */
	void __iomem			*acry_sram;

	/* ACRY input DMA buffer */
	void				*buf_addr;
	dma_addr_t			buf_dma_addr;

	struct crypto_engine		*crypt_engine_rsa;

	/* ACRY SRAM memory mapped */
	int				exp_dw_mapping[ASPEED_ACRY_RSA_MAX_KEY_LEN];
	int				mod_dw_mapping[ASPEED_ACRY_RSA_MAX_KEY_LEN];
	int				data_byte_mapping[ASPEED_ACRY_SRAM_MAX_LEN];
};

struct aspeed_acry_ctx {
	struct aspeed_acry_dev		*acry_dev;

	struct rsa_key			key;
	int				enc;
	u8				*n;
	u8				*e;
	u8				*d;
	size_t				n_sz;
	size_t				e_sz;
	size_t				d_sz;

	aspeed_acry_fn_t		trigger;

	struct crypto_akcipher          *fallback_tfm;
};

struct aspeed_acry_alg {
	struct aspeed_acry_dev		*acry_dev;
	struct akcipher_engine_alg	akcipher;
};

enum aspeed_rsa_key_mode {
	ASPEED_RSA_EXP_MODE = 0,
	ASPEED_RSA_MOD_MODE,
	ASPEED_RSA_DATA_MODE,
};

static inline struct akcipher_request *
	akcipher_request_cast(struct crypto_async_request *req)
{
	return container_of(req, struct akcipher_request, base);
}

static int aspeed_acry_do_fallback(struct akcipher_request *req)
{
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);
	int err;

	akcipher_request_set_tfm(req, ctx->fallback_tfm);

	if (ctx->enc)
		err = crypto_akcipher_encrypt(req);
	else
		err = crypto_akcipher_decrypt(req);

	akcipher_request_set_tfm(req, cipher);

	return err;
}

static bool aspeed_acry_need_fallback(struct akcipher_request *req)
{
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);

	return ctx->key.n_sz > ASPEED_ACRY_RSA_MAX_KEY_LEN;
}

static int aspeed_acry_handle_queue(struct aspeed_acry_dev *acry_dev,
				    struct akcipher_request *req)
{
	if (aspeed_acry_need_fallback(req)) {
		ACRY_DBG(acry_dev, "SW fallback\n");
		return aspeed_acry_do_fallback(req);
	}

	return crypto_transfer_akcipher_request_to_engine(acry_dev->crypt_engine_rsa, req);
}

static int aspeed_acry_do_request(struct crypto_engine *engine, void *areq)
{
	struct akcipher_request *req = akcipher_request_cast(areq);
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);
	struct aspeed_acry_dev *acry_dev = ctx->acry_dev;

	acry_dev->req = req;
	acry_dev->flags |= CRYPTO_FLAGS_BUSY;

	return ctx->trigger(acry_dev);
}

static int aspeed_acry_complete(struct aspeed_acry_dev *acry_dev, int err)
{
	struct akcipher_request *req = acry_dev->req;

	acry_dev->flags &= ~CRYPTO_FLAGS_BUSY;

	crypto_finalize_akcipher_request(acry_dev->crypt_engine_rsa, req, err);

	return err;
}

/*
 * Copy Data to DMA buffer for engine used.
 */
static void aspeed_acry_rsa_sg_copy_to_buffer(struct aspeed_acry_dev *acry_dev,
					      u8 *buf, struct scatterlist *src,
					      size_t nbytes)
{
	static u8 dram_buffer[ASPEED_ACRY_SRAM_MAX_LEN];
	int i = 0, j;
	int data_idx;

	ACRY_DBG(acry_dev, "\n");

	scatterwalk_map_and_copy(dram_buffer, src, 0, nbytes, 0);

	for (j = nbytes - 1; j >= 0; j--) {
		data_idx = acry_dev->data_byte_mapping[i];
		buf[data_idx] =  dram_buffer[j];
		i++;
	}

	for (; i < ASPEED_ACRY_SRAM_MAX_LEN; i++) {
		data_idx = acry_dev->data_byte_mapping[i];
		buf[data_idx] = 0;
	}
}

/*
 * Copy Exp/Mod to DMA buffer for engine used.
 *
 * Params:
 * - mode 0 : Exponential
 * - mode 1 : Modulus
 *
 * Example:
 * - DRAM memory layout:
 *	D[0], D[4], D[8], D[12]
 * - ACRY SRAM memory layout should reverse the order of source data:
 *	D[12], D[8], D[4], D[0]
 */
static int aspeed_acry_rsa_ctx_copy(struct aspeed_acry_dev *acry_dev, void *buf,
				    const void *xbuf, size_t nbytes,
				    enum aspeed_rsa_key_mode mode)
{
	const u8 *src = xbuf;
	__le32 *dw_buf = buf;
	int nbits, ndw;
	int i, j, idx;
	u32 data = 0;

	ACRY_DBG(acry_dev, "nbytes:%zu, mode:%d\n", nbytes, mode);

	if (nbytes > ASPEED_ACRY_RSA_MAX_KEY_LEN)
		return -ENOMEM;

	/* Remove the leading zeros */
	while (nbytes > 0 && src[0] == 0) {
		src++;
		nbytes--;
	}

	nbits = nbytes * 8;
	if (nbytes > 0)
		nbits -= count_leading_zeros(src[0]) - (BITS_PER_LONG - 8);

	/* double-world alignment */
	ndw = DIV_ROUND_UP(nbytes, BYTES_PER_DWORD);

	if (nbytes > 0) {
		i = BYTES_PER_DWORD - nbytes % BYTES_PER_DWORD;
		i %= BYTES_PER_DWORD;

		for (j = ndw; j > 0; j--) {
			for (; i < BYTES_PER_DWORD; i++) {
				data <<= 8;
				data |= *src++;
			}

			i = 0;

			if (mode == ASPEED_RSA_EXP_MODE)
				idx = acry_dev->exp_dw_mapping[j - 1];
			else /* mode == ASPEED_RSA_MOD_MODE */
				idx = acry_dev->mod_dw_mapping[j - 1];

			dw_buf[idx] = cpu_to_le32(data);
		}
	}

	return nbits;
}

static int aspeed_acry_rsa_transfer(struct aspeed_acry_dev *acry_dev)
{
	struct akcipher_request *req = acry_dev->req;
	u8 __iomem *sram_buffer = acry_dev->acry_sram;
	struct scatterlist *out_sg = req->dst;
	static u8 dram_buffer[ASPEED_ACRY_SRAM_MAX_LEN];
	int leading_zero = 1;
	int result_nbytes;
	int i = 0, j;
	int data_idx;

	/* Set Data Memory to AHB(CPU) Access Mode */
	ast_acry_write(acry_dev, ACRY_CMD_DMEM_AHB, ASPEED_ACRY_DMA_CMD);

	/* Disable ACRY SRAM protection */
	regmap_update_bits(acry_dev->ahbc, AHBC_REGION_PROT,
			   REGION_ACRYM, 0);

	result_nbytes = ASPEED_ACRY_SRAM_MAX_LEN;

	for (j = ASPEED_ACRY_SRAM_MAX_LEN - 1; j >= 0; j--) {
		data_idx = acry_dev->data_byte_mapping[j];
		if (readb(sram_buffer + data_idx) == 0 && leading_zero) {
			result_nbytes--;
		} else {
			leading_zero = 0;
			dram_buffer[i] = readb(sram_buffer + data_idx);
			i++;
		}
	}

	ACRY_DBG(acry_dev, "result_nbytes:%d, req->dst_len:%d\n",
		 result_nbytes, req->dst_len);

	if (result_nbytes <= req->dst_len) {
		scatterwalk_map_and_copy(dram_buffer, out_sg, 0, result_nbytes,
					 1);
		req->dst_len = result_nbytes;

	} else {
		dev_err(acry_dev->dev, "RSA engine error!\n");
	}

	memzero_explicit(acry_dev->buf_addr, ASPEED_ACRY_BUFF_SIZE);

	return aspeed_acry_complete(acry_dev, 0);
}

static int aspeed_acry_rsa_trigger(struct aspeed_acry_dev *acry_dev)
{
	struct akcipher_request *req = acry_dev->req;
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);
	int ne, nm;

	if (!ctx->n || !ctx->n_sz) {
		dev_err(acry_dev->dev, "%s: key n is not set\n", __func__);
		return -EINVAL;
	}

	memzero_explicit(acry_dev->buf_addr, ASPEED_ACRY_BUFF_SIZE);

	/* Copy source data to DMA buffer */
	aspeed_acry_rsa_sg_copy_to_buffer(acry_dev, acry_dev->buf_addr,
					  req->src, req->src_len);

	nm = aspeed_acry_rsa_ctx_copy(acry_dev, acry_dev->buf_addr, ctx->n,
				      ctx->n_sz, ASPEED_RSA_MOD_MODE);
	if (ctx->enc) {
		if (!ctx->e || !ctx->e_sz) {
			dev_err(acry_dev->dev, "%s: key e is not set\n",
				__func__);
			return -EINVAL;
		}
		/* Copy key e to DMA buffer */
		ne = aspeed_acry_rsa_ctx_copy(acry_dev, acry_dev->buf_addr,
					      ctx->e, ctx->e_sz,
					      ASPEED_RSA_EXP_MODE);
	} else {
		if (!ctx->d || !ctx->d_sz) {
			dev_err(acry_dev->dev, "%s: key d is not set\n",
				__func__);
			return -EINVAL;
		}
		/* Copy key d to DMA buffer */
		ne = aspeed_acry_rsa_ctx_copy(acry_dev, acry_dev->buf_addr,
					      ctx->key.d, ctx->key.d_sz,
					      ASPEED_RSA_EXP_MODE);
	}

	ast_acry_write(acry_dev, acry_dev->buf_dma_addr,
		       ASPEED_ACRY_DMA_SRC_BASE);
	ast_acry_write(acry_dev, (ne << 16) + nm,
		       ASPEED_ACRY_RSA_KEY_LEN);
	ast_acry_write(acry_dev, ASPEED_ACRY_BUFF_SIZE,
		       ASPEED_ACRY_DMA_LEN);

	acry_dev->resume = aspeed_acry_rsa_transfer;

	/* Enable ACRY SRAM protection */
	regmap_update_bits(acry_dev->ahbc, AHBC_REGION_PROT,
			   REGION_ACRYM, REGION_ACRYM);

	ast_acry_write(acry_dev, ACRY_RSA_ISR, ASPEED_ACRY_INT_MASK);
	ast_acry_write(acry_dev, ACRY_CMD_DMA_SRAM_MODE_RSA |
			  ACRY_CMD_DMA_SRAM_AHB_ENGINE, ASPEED_ACRY_DMA_CMD);

	/* Trigger RSA engines */
	ast_acry_write(acry_dev, ACRY_CMD_RSA_TRIGGER |
			  ACRY_CMD_DMA_RSA_TRIGGER, ASPEED_ACRY_TRIGGER);

	return 0;
}

static int aspeed_acry_rsa_enc(struct akcipher_request *req)
{
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);
	struct aspeed_acry_dev *acry_dev = ctx->acry_dev;

	ctx->trigger = aspeed_acry_rsa_trigger;
	ctx->enc = 1;

	return aspeed_acry_handle_queue(acry_dev, req);
}

static int aspeed_acry_rsa_dec(struct akcipher_request *req)
{
	struct crypto_akcipher *cipher = crypto_akcipher_reqtfm(req);
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(cipher);
	struct aspeed_acry_dev *acry_dev = ctx->acry_dev;

	ctx->trigger = aspeed_acry_rsa_trigger;
	ctx->enc = 0;

	return aspeed_acry_handle_queue(acry_dev, req);
}

static u8 *aspeed_rsa_key_copy(u8 *src, size_t len)
{
	return kmemdup(src, len, GFP_KERNEL);
}

static int aspeed_rsa_set_n(struct aspeed_acry_ctx *ctx, u8 *value,
			    size_t len)
{
	ctx->n_sz = len;
	ctx->n = aspeed_rsa_key_copy(value, len);
	if (!ctx->n)
		return -ENOMEM;

	return 0;
}

static int aspeed_rsa_set_e(struct aspeed_acry_ctx *ctx, u8 *value,
			    size_t len)
{
	ctx->e_sz = len;
	ctx->e = aspeed_rsa_key_copy(value, len);
	if (!ctx->e)
		return -ENOMEM;

	return 0;
}

static int aspeed_rsa_set_d(struct aspeed_acry_ctx *ctx, u8 *value,
			    size_t len)
{
	ctx->d_sz = len;
	ctx->d = aspeed_rsa_key_copy(value, len);
	if (!ctx->d)
		return -ENOMEM;

	return 0;
}

static void aspeed_rsa_key_free(struct aspeed_acry_ctx *ctx)
{
	kfree_sensitive(ctx->n);
	kfree_sensitive(ctx->e);
	kfree_sensitive(ctx->d);
	ctx->n_sz = 0;
	ctx->e_sz = 0;
	ctx->d_sz = 0;
}

static int aspeed_acry_rsa_setkey(struct crypto_akcipher *tfm, const void *key,
				  unsigned int keylen, int priv)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct aspeed_acry_dev *acry_dev = ctx->acry_dev;
	int ret;

	if (priv)
		ret = rsa_parse_priv_key(&ctx->key, key, keylen);
	else
		ret = rsa_parse_pub_key(&ctx->key, key, keylen);

	if (ret) {
		dev_err(acry_dev->dev, "rsa parse key failed, ret:0x%x\n",
			ret);
		return ret;
	}

	/* Aspeed engine supports up to 4096 bits,
	 * Use software fallback instead.
	 */
	if (ctx->key.n_sz > ASPEED_ACRY_RSA_MAX_KEY_LEN)
		return 0;

	ret = aspeed_rsa_set_n(ctx, (u8 *)ctx->key.n, ctx->key.n_sz);
	if (ret)
		goto err;

	ret = aspeed_rsa_set_e(ctx, (u8 *)ctx->key.e, ctx->key.e_sz);
	if (ret)
		goto err;

	if (priv) {
		ret = aspeed_rsa_set_d(ctx, (u8 *)ctx->key.d, ctx->key.d_sz);
		if (ret)
			goto err;
	}

	return 0;

err:
	dev_err(acry_dev->dev, "rsa set key failed\n");
	aspeed_rsa_key_free(ctx);

	return ret;
}

static int aspeed_acry_rsa_set_pub_key(struct crypto_akcipher *tfm,
				       const void *key,
				       unsigned int keylen)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);
	int ret;

	ret = crypto_akcipher_set_pub_key(ctx->fallback_tfm, key, keylen);
	if (ret)
		return ret;

	return aspeed_acry_rsa_setkey(tfm, key, keylen, 0);
}

static int aspeed_acry_rsa_set_priv_key(struct crypto_akcipher *tfm,
					const void *key,
					unsigned int keylen)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);
	int ret;

	ret = crypto_akcipher_set_priv_key(ctx->fallback_tfm, key, keylen);
	if (ret)
		return ret;

	return aspeed_acry_rsa_setkey(tfm, key, keylen, 1);
}

static unsigned int aspeed_acry_rsa_max_size(struct crypto_akcipher *tfm)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);

	if (ctx->key.n_sz > ASPEED_ACRY_RSA_MAX_KEY_LEN)
		return crypto_akcipher_maxsize(ctx->fallback_tfm);

	return ctx->n_sz;
}

static int aspeed_acry_rsa_init_tfm(struct crypto_akcipher *tfm)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
	const char *name = crypto_tfm_alg_name(&tfm->base);
	struct aspeed_acry_alg *acry_alg;

	acry_alg = container_of(alg, struct aspeed_acry_alg, akcipher.base);

	ctx->acry_dev = acry_alg->acry_dev;

	ctx->fallback_tfm = crypto_alloc_akcipher(name, 0, CRYPTO_ALG_ASYNC |
						  CRYPTO_ALG_NEED_FALLBACK);
	if (IS_ERR(ctx->fallback_tfm)) {
		dev_err(ctx->acry_dev->dev, "ERROR: Cannot allocate fallback for %s %ld\n",
			name, PTR_ERR(ctx->fallback_tfm));
		return PTR_ERR(ctx->fallback_tfm);
	}

	return 0;
}

static void aspeed_acry_rsa_exit_tfm(struct crypto_akcipher *tfm)
{
	struct aspeed_acry_ctx *ctx = akcipher_tfm_ctx(tfm);

	crypto_free_akcipher(ctx->fallback_tfm);
}

static struct aspeed_acry_alg aspeed_acry_akcipher_algs[] = {
	{
		.akcipher.base = {
			.encrypt = aspeed_acry_rsa_enc,
			.decrypt = aspeed_acry_rsa_dec,
			.sign = aspeed_acry_rsa_dec,
			.verify = aspeed_acry_rsa_enc,
			.set_pub_key = aspeed_acry_rsa_set_pub_key,
			.set_priv_key = aspeed_acry_rsa_set_priv_key,
			.max_size = aspeed_acry_rsa_max_size,
			.init = aspeed_acry_rsa_init_tfm,
			.exit = aspeed_acry_rsa_exit_tfm,
			.base = {
				.cra_name = "rsa",
				.cra_driver_name = "aspeed-rsa",
				.cra_priority = 300,
				.cra_flags = CRYPTO_ALG_TYPE_AKCIPHER |
					     CRYPTO_ALG_ASYNC |
					     CRYPTO_ALG_KERN_DRIVER_ONLY |
					     CRYPTO_ALG_NEED_FALLBACK,
				.cra_module = THIS_MODULE,
				.cra_ctxsize = sizeof(struct aspeed_acry_ctx),
			},
		},
		.akcipher.op = {
			.do_one_request = aspeed_acry_do_request,
		},
	},
};

static void aspeed_acry_register(struct aspeed_acry_dev *acry_dev)
{
	int i, rc;

	for (i = 0; i < ARRAY_SIZE(aspeed_acry_akcipher_algs); i++) {
		aspeed_acry_akcipher_algs[i].acry_dev = acry_dev;
		rc = crypto_engine_register_akcipher(&aspeed_acry_akcipher_algs[i].akcipher);
		if (rc) {
			ACRY_DBG(acry_dev, "Failed to register %s\n",
				 aspeed_acry_akcipher_algs[i].akcipher.base.base.cra_name);
		}
	}
}

static void aspeed_acry_unregister(struct aspeed_acry_dev *acry_dev)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(aspeed_acry_akcipher_algs); i++)
		crypto_engine_unregister_akcipher(&aspeed_acry_akcipher_algs[i].akcipher);
}

/* ACRY interrupt service routine. */
static irqreturn_t aspeed_acry_irq(int irq, void *dev)
{
	struct aspeed_acry_dev *acry_dev = (struct aspeed_acry_dev *)dev;
	u32 sts;

	sts = ast_acry_read(acry_dev, ASPEED_ACRY_STATUS);
	ast_acry_write(acry_dev, sts, ASPEED_ACRY_STATUS);

	ACRY_DBG(acry_dev, "irq sts:0x%x\n", sts);

	if (sts & ACRY_RSA_ISR) {
		/* Stop RSA engine */
		ast_acry_write(acry_dev, 0, ASPEED_ACRY_TRIGGER);

		if (acry_dev->flags & CRYPTO_FLAGS_BUSY)
			tasklet_schedule(&acry_dev->done_task);
		else
			dev_err(acry_dev->dev, "RSA no active requests.\n");
	}

	return IRQ_HANDLED;
}

/*
 * ACRY SRAM has its own memory layout.
 * Set the DRAM to SRAM indexing for future used.
 */
static void aspeed_acry_sram_mapping(struct aspeed_acry_dev *acry_dev)
{
	int i, j = 0;

	for (i = 0; i < (ASPEED_ACRY_SRAM_MAX_LEN / BYTES_PER_DWORD); i++) {
		acry_dev->exp_dw_mapping[i] = j;
		acry_dev->mod_dw_mapping[i] = j + 4;
		acry_dev->data_byte_mapping[(i * 4)] = (j + 8) * 4;
		acry_dev->data_byte_mapping[(i * 4) + 1] = (j + 8) * 4 + 1;
		acry_dev->data_byte_mapping[(i * 4) + 2] = (j + 8) * 4 + 2;
		acry_dev->data_byte_mapping[(i * 4) + 3] = (j + 8) * 4 + 3;
		j++;
		j = j % 4 ? j : j + 8;
	}
}

static void aspeed_acry_done_task(unsigned long data)
{
	struct aspeed_acry_dev *acry_dev = (struct aspeed_acry_dev *)data;

	(void)acry_dev->resume(acry_dev);
}

static const struct of_device_id aspeed_acry_of_matches[] = {
	{ .compatible = "aspeed,ast2600-acry", },
	{},
};

static int aspeed_acry_probe(struct platform_device *pdev)
{
	struct aspeed_acry_dev *acry_dev;
	struct device *dev = &pdev->dev;
	int rc;

	acry_dev = devm_kzalloc(dev, sizeof(struct aspeed_acry_dev),
				GFP_KERNEL);
	if (!acry_dev)
		return -ENOMEM;

	acry_dev->dev = dev;

	platform_set_drvdata(pdev, acry_dev);

	acry_dev->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(acry_dev->regs))
		return PTR_ERR(acry_dev->regs);

	acry_dev->acry_sram = devm_platform_ioremap_resource(pdev, 1);
	if (IS_ERR(acry_dev->acry_sram))
		return PTR_ERR(acry_dev->acry_sram);

	/* Get irq number and register it */
	acry_dev->irq = platform_get_irq(pdev, 0);
	if (acry_dev->irq < 0)
		return -ENXIO;

	rc = devm_request_irq(dev, acry_dev->irq, aspeed_acry_irq, 0,
			      dev_name(dev), acry_dev);
	if (rc) {
		dev_err(dev, "Failed to request irq.\n");
		return rc;
	}

	acry_dev->clk = devm_clk_get_enabled(dev, NULL);
	if (IS_ERR(acry_dev->clk)) {
		dev_err(dev, "Failed to get acry clk\n");
		return PTR_ERR(acry_dev->clk);
	}

	acry_dev->ahbc = syscon_regmap_lookup_by_phandle(dev->of_node,
							 "aspeed,ahbc");
	if (IS_ERR(acry_dev->ahbc)) {
		dev_err(dev, "Failed to get AHBC regmap\n");
		return -ENODEV;
	}

	/* Initialize crypto hardware engine structure for RSA */
	acry_dev->crypt_engine_rsa = crypto_engine_alloc_init(dev, true);
	if (!acry_dev->crypt_engine_rsa) {
		rc = -ENOMEM;
		goto clk_exit;
	}

	rc = crypto_engine_start(acry_dev->crypt_engine_rsa);
	if (rc)
		goto err_engine_rsa_start;

	tasklet_init(&acry_dev->done_task, aspeed_acry_done_task,
		     (unsigned long)acry_dev);

	/* Set Data Memory to AHB(CPU) Access Mode */
	ast_acry_write(acry_dev, ACRY_CMD_DMEM_AHB, ASPEED_ACRY_DMA_CMD);

	/* Initialize ACRY SRAM index */
	aspeed_acry_sram_mapping(acry_dev);

	acry_dev->buf_addr = dmam_alloc_coherent(dev, ASPEED_ACRY_BUFF_SIZE,
						 &acry_dev->buf_dma_addr,
						 GFP_KERNEL);
	if (!acry_dev->buf_addr) {
		rc = -ENOMEM;
		goto err_engine_rsa_start;
	}

	aspeed_acry_register(acry_dev);

	dev_info(dev, "Aspeed ACRY Accelerator successfully registered\n");

	return 0;

err_engine_rsa_start:
	crypto_engine_exit(acry_dev->crypt_engine_rsa);
clk_exit:
	clk_disable_unprepare(acry_dev->clk);

	return rc;
}

static void aspeed_acry_remove(struct platform_device *pdev)
{
	struct aspeed_acry_dev *acry_dev = platform_get_drvdata(pdev);

	aspeed_acry_unregister(acry_dev);
	crypto_engine_exit(acry_dev->crypt_engine_rsa);
	tasklet_kill(&acry_dev->done_task);
	clk_disable_unprepare(acry_dev->clk);
}

MODULE_DEVICE_TABLE(of, aspeed_acry_of_matches);

static struct platform_driver aspeed_acry_driver = {
	.probe		= aspeed_acry_probe,
	.remove_new	= aspeed_acry_remove,
	.driver		= {
		.name   = KBUILD_MODNAME,
		.of_match_table = aspeed_acry_of_matches,
	},
};

module_platform_driver(aspeed_acry_driver);

MODULE_AUTHOR("Neal Liu <neal_liu@aspeedtech.com>");
MODULE_DESCRIPTION("ASPEED ACRY driver for hardware RSA Engine");
MODULE_LICENSE("GPL");