[3/3] crypto: add basic driver for the MXC SCC

Commit Message

Steffen Trumtrar Feb. 11, 2016, 2:04 p.m. UTC

According to the Freescale GPL driver code, there are two different
Security Controller (SCC) versions: SCC and SCC2.

The SCC is found on older i.MX SoCs, e.g. the i.MX25. This is the
version implemented and tested here.

As there is no publicly available documentation for this IP core,
all information about this unit is gathered from the GPL'ed driver
from Freescale.

Signed-off-by: Steffen Trumtrar <[e-mail]>
---
 drivers/crypto/Kconfig   |   9 +
 drivers/crypto/Makefile  |   1 +
 drivers/crypto/mxc-scc.c | 756 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 766 insertions(+)
 create mode 100644 drivers/crypto/mxc-scc.c

Comments

Lothar Waßmann Feb. 11, 2016, 3:45 p.m. UTC | #1

Hi,

On Thu, 11 Feb 2016 15:04:45 +0100 Steffen Trumtrar wrote:
> According to the Freescale GPL driver code, there are two different
> Security Controller (SCC) versions: SCC and SCC2.
> 
> The SCC is found on older i.MX SoCs, e.g. the i.MX25. This is the
> version implemented and tested here.
> 
> As there is no publicly available documentation for this IP core,
> all information about this unit is gathered from the GPL'ed driver
> from Freescale.
> 
> Signed-off-by: Steffen Trumtrar <[e-mail]>
> ---
>  drivers/crypto/Kconfig   |   9 +
>  drivers/crypto/Makefile  |   1 +
>  drivers/crypto/mxc-scc.c | 756 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 766 insertions(+)
>  create mode 100644 drivers/crypto/mxc-scc.c
> 
> diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
> index 07d494276aad..ece3e231ee4d 100644
> --- a/drivers/crypto/Kconfig
> +++ b/drivers/crypto/Kconfig
> @@ -339,6 +339,15 @@ config CRYPTO_DEV_SAHARA
>  	  This option enables support for the SAHARA HW crypto accelerator
>  	  found in some Freescale i.MX chips.
>  
> +config CRYPTO_DEV_MXC_SCC
> +	tristate "Support for Freescale Security Controller (SCC)"
> +	depends on ARCH_MXC && OF
> +	select CRYPTO_BLKCIPHER
> +	select CRYPTO_DES
> +	help
> +	  This option enables support for the Security Controller (SCC)
> +	  found in Freescale i.MX25 chips.
> +
>  config CRYPTO_DEV_S5P
>  	tristate "Support for Samsung S5PV210/Exynos crypto accelerator"
>  	depends on ARCH_S5PV210 || ARCH_EXYNOS
> diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
> index 713de9d11148..3c6432dd09d9 100644
> --- a/drivers/crypto/Makefile
> +++ b/drivers/crypto/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_CRYPTO_DEV_PICOXCELL) += picoxcell_crypto.o
>  obj-$(CONFIG_CRYPTO_DEV_PPC4XX) += amcc/
>  obj-$(CONFIG_CRYPTO_DEV_S5P) += s5p-sss.o
>  obj-$(CONFIG_CRYPTO_DEV_SAHARA) += sahara.o
> +obj-$(CONFIG_CRYPTO_DEV_MXC_SCC) += mxc-scc.o
>  obj-$(CONFIG_CRYPTO_DEV_TALITOS) += talitos.o
>  obj-$(CONFIG_CRYPTO_DEV_UX500) += ux500/
>  obj-$(CONFIG_CRYPTO_DEV_QAT) += qat/
> diff --git a/drivers/crypto/mxc-scc.c b/drivers/crypto/mxc-scc.c
> new file mode 100644
> index 000000000000..f8cc00d1d92e
> --- /dev/null
> +++ b/drivers/crypto/mxc-scc.c
> @@ -0,0 +1,756 @@
> +/*
> + * Copyright (C) 2016 Pengutronix, Steffen Trumtrar <[e-mail]>
> + *
> + * The driver is based on information gathered from
> + * drivers/mxc/security/mxc_scc.c which can be found in
> + * the Freescale linux-2.6-imx.git in the imx_2.6.35_maintain branch.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +#include <linux/clk.h>
> +#include <linux/crypto.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +
> +#include <crypto/algapi.h>
> +#include <crypto/des.h>
> +
> +/* Secure Memory (SCM) registers */
> +#define SCC_SCM_RED_START		0x0000
> +#define SCC_SCM_BLACK_START		0x0004
> +#define SCC_SCM_LENGTH			0x0008
> +#define SCC_SCM_CTRL			0x000C
> +#define SCC_SCM_STATUS			0x0010
> +#define SCC_SCM_ERROR_STATUS		0x0014
> +#define SCC_SCM_INTR_CTRL		0x0018
> +#define SCC_SCM_CFG			0x001C
> +#define SCC_SCM_INIT_VECTOR_0		0x0020
> +#define SCC_SCM_INIT_VECTOR_1		0x0024
> +#define SCC_SCM_RED_MEMORY		0x0400
> +#define SCC_SCM_BLACK_MEMORY		0x0800
> +
> +/* Security Monitor (SMN) Registers */
> +#define SCC_SMN_STATUS			0x1000
> +#define SCC_SMN_COMMAND		0x1004
> +#define SCC_SMN_SEQ_START		0x1008
> +#define SCC_SMN_SEQ_END		0x100C
> +#define SCC_SMN_SEQ_CHECK		0x1010
> +#define SCC_SMN_BIT_COUNT		0x1014
> +#define SCC_SMN_BITBANK_INC_SIZE	0x1018
> +#define SCC_SMN_BITBANK_DECREMENT	0x101C
> +#define SCC_SMN_COMPARE_SIZE		0x1020
> +#define SCC_SMN_PLAINTEXT_CHECK	0x1024
> +#define SCC_SMN_CIPHERTEXT_CHECK	0x1028
> +#define SCC_SMN_TIMER_IV		0x102C
> +#define SCC_SMN_TIMER_CONTROL		0x1030
> +#define SCC_SMN_DEBUG_DETECT_STAT	0x1034
> +#define SCC_SMN_TIMER			0x1038
> +
> +#define SCC_SCM_CTRL_START_CIPHER	BIT(2)
> +#define SCC_SCM_CTRL_CBC_MODE		BIT(1)
> +#define SCC_SCM_CTRL_DECRYPT_MODE	BIT(0)
> +
> +#define SCC_SCM_STATUS_LEN_ERR		BIT(12)
> +#define SCC_SCM_STATUS_SMN_UNBLOCKED	BIT(11)
> +#define SCC_SCM_STATUS_CIPHERING_DONE	BIT(10)
> +#define SCC_SCM_STATUS_ZEROIZING_DONE	BIT(9)
> +#define SCC_SCM_STATUS_INTR_STATUS	BIT(8)
> +#define SCC_SCM_STATUS_SEC_KEY		BIT(7)
> +#define SCC_SCM_STATUS_INTERNAL_ERR	BIT(6)
> +#define SCC_SCM_STATUS_BAD_SEC_KEY	BIT(5)
> +#define SCC_SCM_STATUS_ZEROIZE_FAIL	BIT(4)
> +#define SCC_SCM_STATUS_SMN_BLOCKED	BIT(3)
> +#define SCC_SCM_STATUS_CIPHERING	BIT(2)
> +#define SCC_SCM_STATUS_ZEROIZING	BIT(1)
> +#define SCC_SCM_STATUS_BUSY		BIT(0)
> +
> +#define SCC_SMN_STATUS_STATE_MASK	0x0000001F
> +#define SCC_SMN_STATE_START		0x0
> +/* The SMN is zeroizing its RAM during reset */
> +#define SCC_SMN_STATE_ZEROIZE_RAM	0x5
> +/* SMN has passed internal checks */
> +#define SCC_SMN_STATE_HEALTH_CHECK	0x6
> +/* Fatal Security Violation. SMN is locked, SCM is inoperative. */
> +#define SCC_SMN_STATE_FAIL		0x9
> +/* SCC is in secure state. SCM is using secret key. */
> +#define SCC_SMN_STATE_SECURE		0xA
> +/* SCC is not secure. SCM is using default key. */
> +#define SCC_SMN_STATE_NON_SECURE	0xC
> +
> +#define SCC_SCM_INTR_CTRL_ZEROIZE_MEM	BIT(2)
> +#define SCC_SCM_INTR_CTRL_CLR_INTR	BIT(1)
> +#define SCC_SCM_INTR_CTRL_MASK_INTR	BIT(0)
> +
> +/* Size, in blocks, of Red memory. */
> +#define SCC_SCM_CFG_BLACK_SIZE_MASK	0x07fe0000
> +#define SCC_SCM_CFG_BLACK_SIZE_SHIFT	17
> +/* Size, in blocks, of Black memory. */
> +#define SCC_SCM_CFG_RED_SIZE_MASK	0x0001ff80
> +#define SCC_SCM_CFG_RED_SIZE_SHIFT	7
> +/* Number of bytes per block. */
> +#define SCC_SCM_CFG_BLOCK_SIZE_MASK	0x0000007f
> +
> +#define SCC_SMN_COMMAND_TAMPER_LOCK	BIT(4)
> +#define SCC_SMN_COMMAND_CLR_INTR	BIT(3)
> +#define SCC_SMN_COMMAND_CLR_BIT_BANK	BIT(2)
> +#define SCC_SMN_COMMAND_EN_INTR	BIT(1)
> +#define SCC_SMN_COMMAND_SET_SOFTWARE_ALARM  BIT(0)
> +
> +#define SCC_KEY_SLOTS			20
> +#define SCC_MAX_KEY_SIZE		32
> +#define SCC_KEY_SLOT_SIZE		32
> +
> +#define SCC_CRC_CCITT_START		0xFFFF
> +
> +/*
> + * Offset into each RAM of the base of the area which is not
> + * used for Stored Keys.
> + */
> +#define SCC_NON_RESERVED_OFFSET	(SCC_KEY_SLOTS * SCC_KEY_SLOT_SIZE)
> +
> +/* Fixed padding for appending to plaintext to fill out a block */
> +static char scc_block_padding[8] = { 0x80, 0, 0, 0, 0, 0, 0, 0 };
> +
> +enum mxc_scc_state {
> +	SCC_STATE_OK,
> +	SCC_STATE_UNIMPLEMENTED,
> +	SCC_STATE_FAILED
> +};
> +
> +struct mxc_scc {
> +	struct device		*dev;
> +	void __iomem		*base;
> +	struct clk		*clk;
> +	struct mutex		mutex;
> +	spinlock_t		lock;
> +	struct crypto_queue	queue;
> +	struct crypto_async_request *req;
> +	int			block_size_bytes;
> +	int			black_ram_size_blocks;
> +	int			memory_size_bytes;
> +	int			bytes_remaining;
> +
> +	void __iomem		*red_memory;
> +	void __iomem		*black_memory;
> +};
> +
> +struct mxc_scc_ctx {
> +	struct mxc_scc		*scc;
> +	struct scatterlist	*sg_src;
> +	size_t			src_nents;
> +	struct scatterlist	*sg_dst;
> +	size_t			dst_nents;
> +	unsigned int		offset;
> +	unsigned int		size;
> +	unsigned int		ctrl;
> +};
> +
> +struct mxc_scc_crypto_tmpl {
> +	struct mxc_scc *scc;
> +	struct crypto_alg alg;
> +};
> +
> +static int mxc_scc_get_data(struct mxc_scc_ctx *ctx,
> +			    struct crypto_async_request *req)
> +{
> +	struct ablkcipher_request *ablkreq = ablkcipher_request_cast(req);
> +	struct mxc_scc *scc = ctx->scc;
> +	size_t len;
> +	void __iomem *from;
> +
> +	if (ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE)
> +		from = scc->red_memory;
> +	else
> +		from = scc->black_memory;
> +
> +	dev_dbg(scc->dev, "pcopy: from 0x%p %d bytes\n", from,
> +		ctx->dst_nents * 8);
> +	len = sg_pcopy_from_buffer(ablkreq->dst, ctx->dst_nents,
> +				   from, ctx->size, ctx->offset);
> +	if (!len) {
> +		dev_err(scc->dev, "pcopy err from 0x%p (len=%d)\n", from, len);
> +		return -EINVAL;
> +	}
> +
> +#ifdef DEBUG
> +	print_hex_dump(KERN_ERR,
> +		       "red memory@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       scc->red_memory, ctx->size, 1);
> +	print_hex_dump(KERN_ERR,
> +		       "black memory@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       scc->black_memory, ctx->size, 1);
> +#endif
> +
> +	ctx->offset += len;
> +
> +	if (ctx->offset < ablkreq->nbytes)
> +		return -EINPROGRESS;
> +
> +	return 0;
> +}
> +
> +static int mxc_scc_ablkcipher_req_init(struct ablkcipher_request *req,
> +				       struct mxc_scc_ctx *ctx)
> +{
> +	struct mxc_scc *scc = ctx->scc;
> +
> +	ctx->src_nents = sg_nents_for_len(req->src, req->nbytes);
> +	if (ctx->src_nents < 0) {
> +		dev_err(scc->dev, "Invalid number of src SC");
> +		return ctx->src_nents;
> +	}
> +
> +	ctx->dst_nents = sg_nents_for_len(req->dst, req->nbytes);
> +	if (ctx->dst_nents < 0) {
> +		dev_err(scc->dev, "Invalid number of dst SC");
> +		return ctx->dst_nents;
> +	}
> +
> +	ctx->size = 0;
> +	ctx->offset = 0;
> +
> +	return 0;
> +}
> +
> +static int mxc_scc_put_data(struct mxc_scc_ctx *ctx,
> +			     struct ablkcipher_request *req)
> +{
> +	u8 padding_buffer[sizeof(u16) + sizeof(scc_block_padding)];
> +	size_t len = min_t(size_t, req->nbytes - ctx->offset,
> +			   ctx->scc->bytes_remaining);
> +	unsigned int padding_byte_count = 0;
> +	struct mxc_scc *scc = ctx->scc;
> +	void __iomem *to;
> +
> +	if (ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE)
> +		to = scc->black_memory;
> +	else
> +		to = scc->red_memory;
> +
> +	if (ctx->ctrl & SCC_SCM_CTRL_CBC_MODE && req->info)
> +		memcpy(scc->base + SCC_SCM_INIT_VECTOR_0, req->info,
> +		       scc->block_size_bytes);
> +
> +	len = sg_pcopy_to_buffer(req->src, ctx->src_nents,
> +				 to, len, ctx->offset);
> +	if (!len) {
> +		dev_err(scc->dev, "pcopy err to 0x%p (len=%d)\n", to, len);
> +		return -EINVAL;
> +	}
> +
> +	ctx->size = len;
> +
> +#ifdef DEBUG
> +	dev_dbg(scc->dev, "copied %d bytes to 0x%p\n", len, to);
> +	print_hex_dump(KERN_ERR,
> +		       "init vector0@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       scc->base + SCC_SCM_INIT_VECTOR_0, scc->block_size_bytes,
> +		       1);
> +	print_hex_dump(KERN_ERR,
> +		       "red memory@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       scc->red_memory, ctx->size, 1);
> +	print_hex_dump(KERN_ERR,
> +		       "black memory@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       scc->black_memory, ctx->size, 1);
> +#endif
> +
> +	scc->bytes_remaining -= len;
> +
> +	padding_byte_count = len % scc->block_size_bytes;
> +
> +	if (padding_byte_count) {
> +		memcpy(padding_buffer, scc_block_padding, padding_byte_count);
> +		memcpy(to + len, padding_buffer, padding_byte_count);
> +		ctx->size += padding_byte_count;
> +	}
> +
> +#ifdef DEBUG
> +	print_hex_dump(KERN_ERR,
> +		       "data to encrypt@"__stringify(__LINE__)": ",
> +		       DUMP_PREFIX_ADDRESS, 16, 4,
> +		       to, ctx->size, 1);
> +#endif
> +
> +	return 0;
> +}
> +
> +static void mxc_scc_ablkcipher_next(struct mxc_scc_ctx *ctx,
> +				    struct crypto_async_request *req)
> +{
> +	struct ablkcipher_request *ablkreq = ablkcipher_request_cast(req);
> +	struct mxc_scc *scc = ctx->scc;
> +	int err;
> +
> +	mutex_lock(&scc->mutex);
> +
> +	dev_dbg(scc->dev, "dispatch request (nbytes=%d, src=%p, dst=%p)\n",
> +		ablkreq->nbytes, ablkreq->src, ablkreq->dst);
> +
> +	writel(0, scc->base + SCC_SCM_ERROR_STATUS);
> +
> +	err = mxc_scc_put_data(ctx, ablkreq);
> +	if (err)
> +		mutex_unlock(&scc->mutex);
> +
Did you really intend to continue with the mutex unlocked in case of
error, or should the error condition be conveyed to the caller somehow?

> +	dev_dbg(scc->dev, "Start encryption (0x%p/0x%p)\n",
> +		(void *)readl(scc->base + SCC_SCM_RED_START),
> +		(void *)readl(scc->base + SCC_SCM_BLACK_START));
> +
> +	/* clear interrupt control registers */
> +	writel(SCC_SCM_INTR_CTRL_CLR_INTR,
> +	       scc->base + SCC_SCM_INTR_CTRL);
> +
> +	writel((ctx->size / ctx->scc->block_size_bytes) - 1,
> +	       scc->base + SCC_SCM_LENGTH);
> +
> +	dev_dbg(scc->dev, "Process %d block(s) in 0x%p\n",
> +		ctx->size / ctx->scc->block_size_bytes,
> +		(ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE) ? scc->black_memory :
> +		scc->red_memory);
> +
> +	writel(ctx->ctrl, scc->base + SCC_SCM_CTRL);
> +}
> +
> +static irqreturn_t mxc_scc_int(int irq, void *priv)
> +{
> +	struct crypto_async_request *req;
> +	struct mxc_scc_ctx *ctx;
> +	struct mxc_scc *scc = priv;
> +	int status;
> +	int ret;
> +
> +	status = readl(scc->base + SCC_SCM_STATUS);
> +
> +	/* clear interrupt control registers */
> +	writel(SCC_SCM_INTR_CTRL_CLR_INTR, scc->base + SCC_SCM_INTR_CTRL);
> +
> +	if (status & SCC_SCM_STATUS_BUSY)
> +		return IRQ_NONE;
> +
> +	spin_lock_bh(&scc->lock);
> +	req = scc->req;
> +	spin_unlock_bh(&scc->lock);
>
What is the purpos of this locking?

> +	if (req) {
> +		ctx = crypto_tfm_ctx(req->tfm);
> +		ret = mxc_scc_get_data(ctx, req);
> +		if (ret != -EINPROGRESS) {
> +			scc->req = NULL;
> +			scc->bytes_remaining = scc->memory_size_bytes;
> +			req->complete(req, ret);
> +			mutex_unlock(&scc->mutex);
> +		} else {
> +			mxc_scc_ablkcipher_next(ctx, req);
> +		}
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int mxc_scc_cra_init(struct crypto_tfm *tfm)
> +{
> +	struct mxc_scc_ctx *ctx = crypto_tfm_ctx(tfm);
> +	struct crypto_alg *alg = tfm->__crt_alg;
> +	struct mxc_scc_crypto_tmpl *algt;
> +
> +	algt = container_of(alg, struct mxc_scc_crypto_tmpl, alg);
> +
> +	ctx->scc = algt->scc;
> +	return 0;
> +}
> +
> +static void mxc_scc_dequeue_req_unlocked(struct mxc_scc_ctx *ctx)
> +{
> +	struct crypto_async_request *req, *backlog;
> +
> +	spin_lock_bh(&ctx->scc->lock);
> +	backlog = crypto_get_backlog(&ctx->scc->queue);
> +	req = crypto_dequeue_request(&ctx->scc->queue);
> +	ctx->scc->req = req;
> +	spin_unlock_bh(&ctx->scc->lock);
> +
> +	if (!req)
> +		return;
> +
> +	if (backlog)
> +		backlog->complete(backlog, -EINPROGRESS);
> +
> +	ctx = crypto_tfm_ctx(req->tfm);
> +	mxc_scc_ablkcipher_next(ctx, req);
> +}
> +
> +
One blank line is sufficient.
 
> +static int mxc_scc_queue_req(struct mxc_scc_ctx *ctx,
> +			     struct crypto_async_request *req)
> +{
> +	int ret;
> +
> +	spin_lock_bh(&ctx->scc->lock);
> +	ret = crypto_enqueue_request(&ctx->scc->queue, req);
> +	spin_unlock_bh(&ctx->scc->lock);
> +
> +	if (ret != -EINPROGRESS)
> +		return ret;
> +
> +	mxc_scc_dequeue_req_unlocked(ctx);
> +
> +	return -EINPROGRESS;
> +}
> +
> +
dto.

> +static int mxc_scc_des3_op(struct mxc_scc_ctx *ctx,
> +			   struct ablkcipher_request *req)
> +{
> +	int err;
> +
> +	err = mxc_scc_ablkcipher_req_init(req, ctx);
> +	if (err)
> +		return err;
> +
> +	return mxc_scc_queue_req(ctx, &req->base);
> +}
> +
> +static int mxc_scc_ecb_des_encrypt(struct ablkcipher_request *req)
> +{
> +	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
> +	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
> +
> +	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
> +
> +	return mxc_scc_des3_op(ctx, req);
> +}
> +
> +static int mxc_scc_ecb_des_decrypt(struct ablkcipher_request *req)
> +{
> +	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
> +	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
> +
> +	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
> +	ctx->ctrl |= SCC_SCM_CTRL_DECRYPT_MODE;
> +
> +	return mxc_scc_des3_op(ctx, req);
> +}
> +
> +static int mxc_scc_cbc_des_encrypt(struct ablkcipher_request *req)
> +{
> +	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
> +	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
> +
> +	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
> +	ctx->ctrl |= SCC_SCM_CTRL_CBC_MODE;
> +
> +	return mxc_scc_des3_op(ctx, req);
> +}
> +
> +static int mxc_scc_cbc_des_decrypt(struct ablkcipher_request *req)
> +{
> +	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
> +	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
> +
> +	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
> +	ctx->ctrl |= SCC_SCM_CTRL_CBC_MODE;
> +	ctx->ctrl |= SCC_SCM_CTRL_DECRYPT_MODE;
> +
> +	return mxc_scc_des3_op(ctx, req);
> +}
> +
> +static void mxc_scc_hw_init(struct mxc_scc *scc)
> +{
> +	int offset;
> +
> +	offset = SCC_NON_RESERVED_OFFSET / scc->block_size_bytes;
> +
> +	/* Fill the RED_START register */
> +	writel(offset, scc->base + SCC_SCM_RED_START);
> +
> +	/* Fill the BLACK_START register */
> +	writel(offset, scc->base + SCC_SCM_BLACK_START);
> +
> +	scc->red_memory = scc->base + SCC_SCM_RED_MEMORY +
> +			  SCC_NON_RESERVED_OFFSET;
> +
> +	scc->black_memory = scc->base + SCC_SCM_BLACK_MEMORY +
> +			    SCC_NON_RESERVED_OFFSET;
> +
> +	scc->bytes_remaining = scc->memory_size_bytes;
> +}
> +
> +static int mxc_scc_get_config(struct mxc_scc *scc)
> +{
> +	int config;
> +
> +	config = readl(scc->base + SCC_SCM_CFG);
> +
> +	scc->block_size_bytes = config & SCC_SCM_CFG_BLOCK_SIZE_MASK;
> +
> +	scc->black_ram_size_blocks = (config & SCC_SCM_CFG_BLACK_SIZE_MASK);
>
useless parens.

[...]
> +static int mxc_scc_crypto_register(struct mxc_scc *scc)
> +{
> +	unsigned int i, k;
> +	int err = 0;
> +
> +	for (i = 0; i < ARRAY_SIZE(scc_crypto_algs); i++) {
> +		scc_crypto_algs[i]->scc = scc;
> +		err = crypto_register_alg(&scc_crypto_algs[i]->alg);
> +		if (err)
> +			goto err_out;
> +	}
> +
> +	return 0;
> +err_out:
>
blank line before label?

> +	for (k = 0; k < i; k++)
> +		crypto_unregister_alg(&scc_crypto_algs[k]->alg);
>
You could decrement i back to zero instead of using another loop index.

[...]
> +static int mxc_scc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	struct mxc_scc *scc;
> +	enum mxc_scc_state state;
> +	int irq;
> +	int ret;
> +
> +	scc = devm_kzalloc(dev, sizeof(*scc), GFP_KERNEL);
> +	if (!scc)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENOENT;
>
No need for this check, devm_ioremap_resource() will take care of it.

> +	scc->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(scc->base))
> +		return PTR_ERR(scc->base);
> +
> +	scc->clk = devm_clk_get(&pdev->dev, "ipg");
> +	if (IS_ERR(scc->clk)) {
> +		dev_err(dev, "Could not get ipg clock\n");
> +		return PTR_ERR(scc->clk);
> +	}
> +
> +	clk_prepare_enable(scc->clk);
> +
> +	/* clear error status register */
> +	writel(0x0, scc->base + SCC_SCM_ERROR_STATUS);
> +
> +	/* clear interrupt control registers */
> +	writel(SCC_SCM_INTR_CTRL_CLR_INTR |
> +	       SCC_SCM_INTR_CTRL_MASK_INTR,
> +	       scc->base + SCC_SCM_INTR_CTRL);
> +
> +	writel(SCC_SMN_COMMAND_CLR_INTR |
> +	       SCC_SMN_COMMAND_EN_INTR,
> +	       scc->base + SCC_SMN_COMMAND);
> +
> +	scc->dev = dev;
> +	platform_set_drvdata(pdev, scc);
> +
> +	ret = mxc_scc_get_config(scc);
> +	if (ret)
> +		goto err_out;
> +
> +	state = mxc_scc_get_state(scc);
> +
> +	if (state != SCC_STATE_OK) {
> +		dev_err(dev, "SCC in unusable state %d\n", state);
> +		ret = -EINVAL;
> +		goto err_out;
> +	}
> +
> +	mxc_scc_hw_init(scc);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(dev, "failed to get irq resource\n");
> +		goto err_out;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, irq, NULL, mxc_scc_int,
> +					IRQF_ONESHOT, dev_name(dev), scc);
> +	if (ret)
> +		goto err_out;
> +
This should be removed, as it is done below again after initializing
all data structures that might be used by the interrupt handler.

> +	irq = platform_get_irq(pdev, 1);
> +	if (irq < 0) {
> +		dev_err(dev, "failed to get irq resource\n");
> +		goto err_out;
> +	}
> +
> +	mutex_init(&scc->mutex);
> +	spin_lock_init(&scc->lock);
> +	/* FIXME: calculate queue from RAM slots */
> +	crypto_init_queue(&scc->queue, 50);
> +
> +	ret = devm_request_threaded_irq(dev, irq, NULL, mxc_scc_int,
> +					IRQF_ONESHOT, dev_name(dev), scc);
> +	if (ret)
> +		goto err_out;
> +
> +	ret = mxc_scc_crypto_register(scc);
> +	if (ret) {
> +		dev_err(dev, "could not register algorithms");
> +		goto err_out;
> +	}
> +
> +	dev_info(dev, "registered successfully.\n");
> +
> +	return 0;
> +
> +err_out:
> +	clk_disable_unprepare(scc->clk);
> +
> +	return ret;
> +}
> +
> +static int mxc_scc_remove(struct platform_device *pdev)
> +{
> +	struct mxc_scc *scc = platform_get_drvdata(pdev);
> +
> +	mxc_scc_crypto_unregister();
> +
> +	clk_disable_unprepare(scc->clk);
> +
> +	return 0;
> +}


Lothar Waßmann
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Patch

diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 07d494276aad..ece3e231ee4d 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -339,6 +339,15 @@  config CRYPTO_DEV_SAHARA
 	  This option enables support for the SAHARA HW crypto accelerator
 	  found in some Freescale i.MX chips.
 
+config CRYPTO_DEV_MXC_SCC
+	tristate "Support for Freescale Security Controller (SCC)"
+	depends on ARCH_MXC && OF
+	select CRYPTO_BLKCIPHER
+	select CRYPTO_DES
+	help
+	  This option enables support for the Security Controller (SCC)
+	  found in Freescale i.MX25 chips.
+
 config CRYPTO_DEV_S5P
 	tristate "Support for Samsung S5PV210/Exynos crypto accelerator"
 	depends on ARCH_S5PV210 || ARCH_EXYNOS
diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
index 713de9d11148..3c6432dd09d9 100644
--- a/drivers/crypto/Makefile
+++ b/drivers/crypto/Makefile
@@ -23,6 +23,7 @@  obj-$(CONFIG_CRYPTO_DEV_PICOXCELL) += picoxcell_crypto.o
 obj-$(CONFIG_CRYPTO_DEV_PPC4XX) += amcc/
 obj-$(CONFIG_CRYPTO_DEV_S5P) += s5p-sss.o
 obj-$(CONFIG_CRYPTO_DEV_SAHARA) += sahara.o
+obj-$(CONFIG_CRYPTO_DEV_MXC_SCC) += mxc-scc.o
 obj-$(CONFIG_CRYPTO_DEV_TALITOS) += talitos.o
 obj-$(CONFIG_CRYPTO_DEV_UX500) += ux500/
 obj-$(CONFIG_CRYPTO_DEV_QAT) += qat/
diff --git a/drivers/crypto/mxc-scc.c b/drivers/crypto/mxc-scc.c
new file mode 100644
index 000000000000..f8cc00d1d92e
--- /dev/null
+++ b/drivers/crypto/mxc-scc.c
@@ -0,0 +1,756 @@ 
+/*
+ * Copyright (C) 2016 Pengutronix, Steffen Trumtrar <[e-mail]>
+ *
+ * The driver is based on information gathered from
+ * drivers/mxc/security/mxc_scc.c which can be found in
+ * the Freescale linux-2.6-imx.git in the imx_2.6.35_maintain branch.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <linux/clk.h>
+#include <linux/crypto.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#include <crypto/algapi.h>
+#include <crypto/des.h>
+
+/* Secure Memory (SCM) registers */
+#define SCC_SCM_RED_START		0x0000
+#define SCC_SCM_BLACK_START		0x0004
+#define SCC_SCM_LENGTH			0x0008
+#define SCC_SCM_CTRL			0x000C
+#define SCC_SCM_STATUS			0x0010
+#define SCC_SCM_ERROR_STATUS		0x0014
+#define SCC_SCM_INTR_CTRL		0x0018
+#define SCC_SCM_CFG			0x001C
+#define SCC_SCM_INIT_VECTOR_0		0x0020
+#define SCC_SCM_INIT_VECTOR_1		0x0024
+#define SCC_SCM_RED_MEMORY		0x0400
+#define SCC_SCM_BLACK_MEMORY		0x0800
+
+/* Security Monitor (SMN) Registers */
+#define SCC_SMN_STATUS			0x1000
+#define SCC_SMN_COMMAND		0x1004
+#define SCC_SMN_SEQ_START		0x1008
+#define SCC_SMN_SEQ_END		0x100C
+#define SCC_SMN_SEQ_CHECK		0x1010
+#define SCC_SMN_BIT_COUNT		0x1014
+#define SCC_SMN_BITBANK_INC_SIZE	0x1018
+#define SCC_SMN_BITBANK_DECREMENT	0x101C
+#define SCC_SMN_COMPARE_SIZE		0x1020
+#define SCC_SMN_PLAINTEXT_CHECK	0x1024
+#define SCC_SMN_CIPHERTEXT_CHECK	0x1028
+#define SCC_SMN_TIMER_IV		0x102C
+#define SCC_SMN_TIMER_CONTROL		0x1030
+#define SCC_SMN_DEBUG_DETECT_STAT	0x1034
+#define SCC_SMN_TIMER			0x1038
+
+#define SCC_SCM_CTRL_START_CIPHER	BIT(2)
+#define SCC_SCM_CTRL_CBC_MODE		BIT(1)
+#define SCC_SCM_CTRL_DECRYPT_MODE	BIT(0)
+
+#define SCC_SCM_STATUS_LEN_ERR		BIT(12)
+#define SCC_SCM_STATUS_SMN_UNBLOCKED	BIT(11)
+#define SCC_SCM_STATUS_CIPHERING_DONE	BIT(10)
+#define SCC_SCM_STATUS_ZEROIZING_DONE	BIT(9)
+#define SCC_SCM_STATUS_INTR_STATUS	BIT(8)
+#define SCC_SCM_STATUS_SEC_KEY		BIT(7)
+#define SCC_SCM_STATUS_INTERNAL_ERR	BIT(6)
+#define SCC_SCM_STATUS_BAD_SEC_KEY	BIT(5)
+#define SCC_SCM_STATUS_ZEROIZE_FAIL	BIT(4)
+#define SCC_SCM_STATUS_SMN_BLOCKED	BIT(3)
+#define SCC_SCM_STATUS_CIPHERING	BIT(2)
+#define SCC_SCM_STATUS_ZEROIZING	BIT(1)
+#define SCC_SCM_STATUS_BUSY		BIT(0)
+
+#define SCC_SMN_STATUS_STATE_MASK	0x0000001F
+#define SCC_SMN_STATE_START		0x0
+/* The SMN is zeroizing its RAM during reset */
+#define SCC_SMN_STATE_ZEROIZE_RAM	0x5
+/* SMN has passed internal checks */
+#define SCC_SMN_STATE_HEALTH_CHECK	0x6
+/* Fatal Security Violation. SMN is locked, SCM is inoperative. */
+#define SCC_SMN_STATE_FAIL		0x9
+/* SCC is in secure state. SCM is using secret key. */
+#define SCC_SMN_STATE_SECURE		0xA
+/* SCC is not secure. SCM is using default key. */
+#define SCC_SMN_STATE_NON_SECURE	0xC
+
+#define SCC_SCM_INTR_CTRL_ZEROIZE_MEM	BIT(2)
+#define SCC_SCM_INTR_CTRL_CLR_INTR	BIT(1)
+#define SCC_SCM_INTR_CTRL_MASK_INTR	BIT(0)
+
+/* Size, in blocks, of Red memory. */
+#define SCC_SCM_CFG_BLACK_SIZE_MASK	0x07fe0000
+#define SCC_SCM_CFG_BLACK_SIZE_SHIFT	17
+/* Size, in blocks, of Black memory. */
+#define SCC_SCM_CFG_RED_SIZE_MASK	0x0001ff80
+#define SCC_SCM_CFG_RED_SIZE_SHIFT	7
+/* Number of bytes per block. */
+#define SCC_SCM_CFG_BLOCK_SIZE_MASK	0x0000007f
+
+#define SCC_SMN_COMMAND_TAMPER_LOCK	BIT(4)
+#define SCC_SMN_COMMAND_CLR_INTR	BIT(3)
+#define SCC_SMN_COMMAND_CLR_BIT_BANK	BIT(2)
+#define SCC_SMN_COMMAND_EN_INTR	BIT(1)
+#define SCC_SMN_COMMAND_SET_SOFTWARE_ALARM  BIT(0)
+
+#define SCC_KEY_SLOTS			20
+#define SCC_MAX_KEY_SIZE		32
+#define SCC_KEY_SLOT_SIZE		32
+
+#define SCC_CRC_CCITT_START		0xFFFF
+
+/*
+ * Offset into each RAM of the base of the area which is not
+ * used for Stored Keys.
+ */
+#define SCC_NON_RESERVED_OFFSET	(SCC_KEY_SLOTS * SCC_KEY_SLOT_SIZE)
+
+/* Fixed padding for appending to plaintext to fill out a block */
+static char scc_block_padding[8] = { 0x80, 0, 0, 0, 0, 0, 0, 0 };
+
+enum mxc_scc_state {
+	SCC_STATE_OK,
+	SCC_STATE_UNIMPLEMENTED,
+	SCC_STATE_FAILED
+};
+
+struct mxc_scc {
+	struct device		*dev;
+	void __iomem		*base;
+	struct clk		*clk;
+	struct mutex		mutex;
+	spinlock_t		lock;
+	struct crypto_queue	queue;
+	struct crypto_async_request *req;
+	int			block_size_bytes;
+	int			black_ram_size_blocks;
+	int			memory_size_bytes;
+	int			bytes_remaining;
+
+	void __iomem		*red_memory;
+	void __iomem		*black_memory;
+};
+
+struct mxc_scc_ctx {
+	struct mxc_scc		*scc;
+	struct scatterlist	*sg_src;
+	size_t			src_nents;
+	struct scatterlist	*sg_dst;
+	size_t			dst_nents;
+	unsigned int		offset;
+	unsigned int		size;
+	unsigned int		ctrl;
+};
+
+struct mxc_scc_crypto_tmpl {
+	struct mxc_scc *scc;
+	struct crypto_alg alg;
+};
+
+static int mxc_scc_get_data(struct mxc_scc_ctx *ctx,
+			    struct crypto_async_request *req)
+{
+	struct ablkcipher_request *ablkreq = ablkcipher_request_cast(req);
+	struct mxc_scc *scc = ctx->scc;
+	size_t len;
+	void __iomem *from;
+
+	if (ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE)
+		from = scc->red_memory;
+	else
+		from = scc->black_memory;
+
+	dev_dbg(scc->dev, "pcopy: from 0x%p %d bytes\n", from,
+		ctx->dst_nents * 8);
+	len = sg_pcopy_from_buffer(ablkreq->dst, ctx->dst_nents,
+				   from, ctx->size, ctx->offset);
+	if (!len) {
+		dev_err(scc->dev, "pcopy err from 0x%p (len=%d)\n", from, len);
+		return -EINVAL;
+	}
+
+#ifdef DEBUG
+	print_hex_dump(KERN_ERR,
+		       "red memory@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       scc->red_memory, ctx->size, 1);
+	print_hex_dump(KERN_ERR,
+		       "black memory@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       scc->black_memory, ctx->size, 1);
+#endif
+
+	ctx->offset += len;
+
+	if (ctx->offset < ablkreq->nbytes)
+		return -EINPROGRESS;
+
+	return 0;
+}
+
+static int mxc_scc_ablkcipher_req_init(struct ablkcipher_request *req,
+				       struct mxc_scc_ctx *ctx)
+{
+	struct mxc_scc *scc = ctx->scc;
+
+	ctx->src_nents = sg_nents_for_len(req->src, req->nbytes);
+	if (ctx->src_nents < 0) {
+		dev_err(scc->dev, "Invalid number of src SC");
+		return ctx->src_nents;
+	}
+
+	ctx->dst_nents = sg_nents_for_len(req->dst, req->nbytes);
+	if (ctx->dst_nents < 0) {
+		dev_err(scc->dev, "Invalid number of dst SC");
+		return ctx->dst_nents;
+	}
+
+	ctx->size = 0;
+	ctx->offset = 0;
+
+	return 0;
+}
+
+static int mxc_scc_put_data(struct mxc_scc_ctx *ctx,
+			     struct ablkcipher_request *req)
+{
+	u8 padding_buffer[sizeof(u16) + sizeof(scc_block_padding)];
+	size_t len = min_t(size_t, req->nbytes - ctx->offset,
+			   ctx->scc->bytes_remaining);
+	unsigned int padding_byte_count = 0;
+	struct mxc_scc *scc = ctx->scc;
+	void __iomem *to;
+
+	if (ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE)
+		to = scc->black_memory;
+	else
+		to = scc->red_memory;
+
+	if (ctx->ctrl & SCC_SCM_CTRL_CBC_MODE && req->info)
+		memcpy(scc->base + SCC_SCM_INIT_VECTOR_0, req->info,
+		       scc->block_size_bytes);
+
+	len = sg_pcopy_to_buffer(req->src, ctx->src_nents,
+				 to, len, ctx->offset);
+	if (!len) {
+		dev_err(scc->dev, "pcopy err to 0x%p (len=%d)\n", to, len);
+		return -EINVAL;
+	}
+
+	ctx->size = len;
+
+#ifdef DEBUG
+	dev_dbg(scc->dev, "copied %d bytes to 0x%p\n", len, to);
+	print_hex_dump(KERN_ERR,
+		       "init vector0@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       scc->base + SCC_SCM_INIT_VECTOR_0, scc->block_size_bytes,
+		       1);
+	print_hex_dump(KERN_ERR,
+		       "red memory@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       scc->red_memory, ctx->size, 1);
+	print_hex_dump(KERN_ERR,
+		       "black memory@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       scc->black_memory, ctx->size, 1);
+#endif
+
+	scc->bytes_remaining -= len;
+
+	padding_byte_count = len % scc->block_size_bytes;
+
+	if (padding_byte_count) {
+		memcpy(padding_buffer, scc_block_padding, padding_byte_count);
+		memcpy(to + len, padding_buffer, padding_byte_count);
+		ctx->size += padding_byte_count;
+	}
+
+#ifdef DEBUG
+	print_hex_dump(KERN_ERR,
+		       "data to encrypt@"__stringify(__LINE__)": ",
+		       DUMP_PREFIX_ADDRESS, 16, 4,
+		       to, ctx->size, 1);
+#endif
+
+	return 0;
+}
+
+static void mxc_scc_ablkcipher_next(struct mxc_scc_ctx *ctx,
+				    struct crypto_async_request *req)
+{
+	struct ablkcipher_request *ablkreq = ablkcipher_request_cast(req);
+	struct mxc_scc *scc = ctx->scc;
+	int err;
+
+	mutex_lock(&scc->mutex);
+
+	dev_dbg(scc->dev, "dispatch request (nbytes=%d, src=%p, dst=%p)\n",
+		ablkreq->nbytes, ablkreq->src, ablkreq->dst);
+
+	writel(0, scc->base + SCC_SCM_ERROR_STATUS);
+
+	err = mxc_scc_put_data(ctx, ablkreq);
+	if (err)
+		mutex_unlock(&scc->mutex);
+
+	dev_dbg(scc->dev, "Start encryption (0x%p/0x%p)\n",
+		(void *)readl(scc->base + SCC_SCM_RED_START),
+		(void *)readl(scc->base + SCC_SCM_BLACK_START));
+
+	/* clear interrupt control registers */
+	writel(SCC_SCM_INTR_CTRL_CLR_INTR,
+	       scc->base + SCC_SCM_INTR_CTRL);
+
+	writel((ctx->size / ctx->scc->block_size_bytes) - 1,
+	       scc->base + SCC_SCM_LENGTH);
+
+	dev_dbg(scc->dev, "Process %d block(s) in 0x%p\n",
+		ctx->size / ctx->scc->block_size_bytes,
+		(ctx->ctrl & SCC_SCM_CTRL_DECRYPT_MODE) ? scc->black_memory :
+		scc->red_memory);
+
+	writel(ctx->ctrl, scc->base + SCC_SCM_CTRL);
+}
+
+static irqreturn_t mxc_scc_int(int irq, void *priv)
+{
+	struct crypto_async_request *req;
+	struct mxc_scc_ctx *ctx;
+	struct mxc_scc *scc = priv;
+	int status;
+	int ret;
+
+	status = readl(scc->base + SCC_SCM_STATUS);
+
+	/* clear interrupt control registers */
+	writel(SCC_SCM_INTR_CTRL_CLR_INTR, scc->base + SCC_SCM_INTR_CTRL);
+
+	if (status & SCC_SCM_STATUS_BUSY)
+		return IRQ_NONE;
+
+	spin_lock_bh(&scc->lock);
+	req = scc->req;
+	spin_unlock_bh(&scc->lock);
+	if (req) {
+		ctx = crypto_tfm_ctx(req->tfm);
+		ret = mxc_scc_get_data(ctx, req);
+		if (ret != -EINPROGRESS) {
+			scc->req = NULL;
+			scc->bytes_remaining = scc->memory_size_bytes;
+			req->complete(req, ret);
+			mutex_unlock(&scc->mutex);
+		} else {
+			mxc_scc_ablkcipher_next(ctx, req);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int mxc_scc_cra_init(struct crypto_tfm *tfm)
+{
+	struct mxc_scc_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_alg *alg = tfm->__crt_alg;
+	struct mxc_scc_crypto_tmpl *algt;
+
+	algt = container_of(alg, struct mxc_scc_crypto_tmpl, alg);
+
+	ctx->scc = algt->scc;
+	return 0;
+}
+
+static void mxc_scc_dequeue_req_unlocked(struct mxc_scc_ctx *ctx)
+{
+	struct crypto_async_request *req, *backlog;
+
+	spin_lock_bh(&ctx->scc->lock);
+	backlog = crypto_get_backlog(&ctx->scc->queue);
+	req = crypto_dequeue_request(&ctx->scc->queue);
+	ctx->scc->req = req;
+	spin_unlock_bh(&ctx->scc->lock);
+
+	if (!req)
+		return;
+
+	if (backlog)
+		backlog->complete(backlog, -EINPROGRESS);
+
+	ctx = crypto_tfm_ctx(req->tfm);
+	mxc_scc_ablkcipher_next(ctx, req);
+}
+
+
+static int mxc_scc_queue_req(struct mxc_scc_ctx *ctx,
+			     struct crypto_async_request *req)
+{
+	int ret;
+
+	spin_lock_bh(&ctx->scc->lock);
+	ret = crypto_enqueue_request(&ctx->scc->queue, req);
+	spin_unlock_bh(&ctx->scc->lock);
+
+	if (ret != -EINPROGRESS)
+		return ret;
+
+	mxc_scc_dequeue_req_unlocked(ctx);
+
+	return -EINPROGRESS;
+}
+
+
+static int mxc_scc_des3_op(struct mxc_scc_ctx *ctx,
+			   struct ablkcipher_request *req)
+{
+	int err;
+
+	err = mxc_scc_ablkcipher_req_init(req, ctx);
+	if (err)
+		return err;
+
+	return mxc_scc_queue_req(ctx, &req->base);
+}
+
+static int mxc_scc_ecb_des_encrypt(struct ablkcipher_request *req)
+{
+	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
+	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
+
+	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
+
+	return mxc_scc_des3_op(ctx, req);
+}
+
+static int mxc_scc_ecb_des_decrypt(struct ablkcipher_request *req)
+{
+	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
+	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
+
+	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
+	ctx->ctrl |= SCC_SCM_CTRL_DECRYPT_MODE;
+
+	return mxc_scc_des3_op(ctx, req);
+}
+
+static int mxc_scc_cbc_des_encrypt(struct ablkcipher_request *req)
+{
+	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
+	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
+
+	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
+	ctx->ctrl |= SCC_SCM_CTRL_CBC_MODE;
+
+	return mxc_scc_des3_op(ctx, req);
+}
+
+static int mxc_scc_cbc_des_decrypt(struct ablkcipher_request *req)
+{
+	struct crypto_ablkcipher *cipher = crypto_ablkcipher_reqtfm(req);
+	struct mxc_scc_ctx *ctx = crypto_ablkcipher_ctx(cipher);
+
+	ctx->ctrl = SCC_SCM_CTRL_START_CIPHER;
+	ctx->ctrl |= SCC_SCM_CTRL_CBC_MODE;
+	ctx->ctrl |= SCC_SCM_CTRL_DECRYPT_MODE;
+
+	return mxc_scc_des3_op(ctx, req);
+}
+
+static void mxc_scc_hw_init(struct mxc_scc *scc)
+{
+	int offset;
+
+	offset = SCC_NON_RESERVED_OFFSET / scc->block_size_bytes;
+
+	/* Fill the RED_START register */
+	writel(offset, scc->base + SCC_SCM_RED_START);
+
+	/* Fill the BLACK_START register */
+	writel(offset, scc->base + SCC_SCM_BLACK_START);
+
+	scc->red_memory = scc->base + SCC_SCM_RED_MEMORY +
+			  SCC_NON_RESERVED_OFFSET;
+
+	scc->black_memory = scc->base + SCC_SCM_BLACK_MEMORY +
+			    SCC_NON_RESERVED_OFFSET;
+
+	scc->bytes_remaining = scc->memory_size_bytes;
+}
+
+static int mxc_scc_get_config(struct mxc_scc *scc)
+{
+	int config;
+
+	config = readl(scc->base + SCC_SCM_CFG);
+
+	scc->block_size_bytes = config & SCC_SCM_CFG_BLOCK_SIZE_MASK;
+
+	scc->black_ram_size_blocks = (config & SCC_SCM_CFG_BLACK_SIZE_MASK);
+
+	scc->memory_size_bytes = (scc->block_size_bytes *
+				  scc->black_ram_size_blocks) -
+				  SCC_NON_RESERVED_OFFSET;
+
+	return 0;
+}
+
+static enum mxc_scc_state mxc_scc_get_state(struct mxc_scc *scc)
+{
+	enum mxc_scc_state state;
+	int status;
+
+	status = readl(scc->base + SCC_SMN_STATUS) &
+		       SCC_SMN_STATUS_STATE_MASK;
+
+	/* If in Health Check, try to bringup to secure state */
+	if (status & SCC_SMN_STATE_HEALTH_CHECK) {
+		/*
+		 * Write a simple algorithm to the Algorithm Sequence
+		 * Checker (ASC)
+		 */
+		writel(0xaaaa, scc->base + SCC_SMN_SEQ_START);
+		writel(0x5555, scc->base + SCC_SMN_SEQ_END);
+		writel(0x5555, scc->base + SCC_SMN_SEQ_CHECK);
+
+		status = readl(scc->base + SCC_SMN_STATUS) &
+			       SCC_SMN_STATUS_STATE_MASK;
+	}
+
+	switch (status) {
+	case SCC_SMN_STATE_NON_SECURE:
+	case SCC_SMN_STATE_SECURE:
+		state = SCC_STATE_OK;
+		break;
+	case SCC_SMN_STATE_FAIL:
+		state = SCC_STATE_FAILED;
+		break;
+	default:
+		state = SCC_STATE_UNIMPLEMENTED;
+		break;
+	}
+
+	return state;
+}
+
+static struct mxc_scc_crypto_tmpl scc_ecb_des = {
+	.alg = {
+		.cra_name = "ecb(des3_ede)",
+		.cra_driver_name = "ecb-des3-scc",
+		.cra_priority = 300,
+		.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER,
+		.cra_blocksize = DES3_EDE_BLOCK_SIZE,
+		.cra_ctxsize = sizeof(struct mxc_scc_ctx),
+		.cra_alignmask = 0,
+		.cra_type = &crypto_ablkcipher_type,
+		.cra_module = THIS_MODULE,
+		.cra_init = mxc_scc_cra_init,
+		.cra_u.ablkcipher = {
+			.min_keysize = DES3_EDE_KEY_SIZE,
+			.max_keysize = DES3_EDE_KEY_SIZE,
+			.encrypt = mxc_scc_ecb_des_encrypt,
+			.decrypt = mxc_scc_ecb_des_decrypt,
+		}
+	}
+};
+
+static struct mxc_scc_crypto_tmpl scc_cbc_des = {
+	.alg = {
+		.cra_name = "cbc(des3_ede)",
+		.cra_driver_name = "cbc-des3-scc",
+		.cra_priority = 300,
+		.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER,
+		.cra_blocksize = DES3_EDE_BLOCK_SIZE,
+		.cra_ctxsize = sizeof(struct mxc_scc_ctx),
+		.cra_alignmask = 0,
+		.cra_type = &crypto_ablkcipher_type,
+		.cra_module = THIS_MODULE,
+		.cra_init = mxc_scc_cra_init,
+		.cra_u.ablkcipher = {
+			.min_keysize = DES3_EDE_KEY_SIZE,
+			.max_keysize = DES3_EDE_KEY_SIZE,
+			.encrypt = mxc_scc_cbc_des_encrypt,
+			.decrypt = mxc_scc_cbc_des_decrypt,
+		}
+	}
+};
+
+static struct mxc_scc_crypto_tmpl *scc_crypto_algs[] = {
+	&scc_ecb_des,
+	&scc_cbc_des,
+};
+
+static int mxc_scc_crypto_register(struct mxc_scc *scc)
+{
+	unsigned int i, k;
+	int err = 0;
+
+	for (i = 0; i < ARRAY_SIZE(scc_crypto_algs); i++) {
+		scc_crypto_algs[i]->scc = scc;
+		err = crypto_register_alg(&scc_crypto_algs[i]->alg);
+		if (err)
+			goto err_out;
+	}
+
+	return 0;
+err_out:
+	for (k = 0; k < i; k++)
+		crypto_unregister_alg(&scc_crypto_algs[k]->alg);
+	return err;
+}
+
+static void mxc_scc_crypto_unregister(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(scc_crypto_algs); i++)
+		crypto_unregister_alg(&scc_crypto_algs[i]->alg);
+}
+
+static int mxc_scc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct mxc_scc *scc;
+	enum mxc_scc_state state;
+	int irq;
+	int ret;
+
+	scc = devm_kzalloc(dev, sizeof(*scc), GFP_KERNEL);
+	if (!scc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	scc->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(scc->base))
+		return PTR_ERR(scc->base);
+
+	scc->clk = devm_clk_get(&pdev->dev, "ipg");
+	if (IS_ERR(scc->clk)) {
+		dev_err(dev, "Could not get ipg clock\n");
+		return PTR_ERR(scc->clk);
+	}
+
+	clk_prepare_enable(scc->clk);
+
+	/* clear error status register */
+	writel(0x0, scc->base + SCC_SCM_ERROR_STATUS);
+
+	/* clear interrupt control registers */
+	writel(SCC_SCM_INTR_CTRL_CLR_INTR |
+	       SCC_SCM_INTR_CTRL_MASK_INTR,
+	       scc->base + SCC_SCM_INTR_CTRL);
+
+	writel(SCC_SMN_COMMAND_CLR_INTR |
+	       SCC_SMN_COMMAND_EN_INTR,
+	       scc->base + SCC_SMN_COMMAND);
+
+	scc->dev = dev;
+	platform_set_drvdata(pdev, scc);
+
+	ret = mxc_scc_get_config(scc);
+	if (ret)
+		goto err_out;
+
+	state = mxc_scc_get_state(scc);
+
+	if (state != SCC_STATE_OK) {
+		dev_err(dev, "SCC in unusable state %d\n", state);
+		ret = -EINVAL;
+		goto err_out;
+	}
+
+	mxc_scc_hw_init(scc);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev, "failed to get irq resource\n");
+		goto err_out;
+	}
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, mxc_scc_int,
+					IRQF_ONESHOT, dev_name(dev), scc);
+	if (ret)
+		goto err_out;
+
+	irq = platform_get_irq(pdev, 1);
+	if (irq < 0) {
+		dev_err(dev, "failed to get irq resource\n");
+		goto err_out;
+	}
+
+	mutex_init(&scc->mutex);
+	spin_lock_init(&scc->lock);
+	/* FIXME: calculate queue from RAM slots */
+	crypto_init_queue(&scc->queue, 50);
+
+	ret = devm_request_threaded_irq(dev, irq, NULL, mxc_scc_int,
+					IRQF_ONESHOT, dev_name(dev), scc);
+	if (ret)
+		goto err_out;
+
+	ret = mxc_scc_crypto_register(scc);
+	if (ret) {
+		dev_err(dev, "could not register algorithms");
+		goto err_out;
+	}
+
+	dev_info(dev, "registered successfully.\n");
+
+	return 0;
+
+err_out:
+	clk_disable_unprepare(scc->clk);
+
+	return ret;
+}
+
+static int mxc_scc_remove(struct platform_device *pdev)
+{
+	struct mxc_scc *scc = platform_get_drvdata(pdev);
+
+	mxc_scc_crypto_unregister();
+
+	clk_disable_unprepare(scc->clk);
+
+	return 0;
+}
+
+static const struct of_device_id mxc_scc_dt_ids[] = {
+	{ .compatible = "fsl,imx25-scc", .data = NULL, },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxc_scc_dt_ids);
+
+static struct platform_driver mxc_scc_driver = {
+	.probe	= mxc_scc_probe,
+	.remove	= mxc_scc_remove,
+	.driver	= {
+		.name		= "mxc-scc",
+		.of_match_table	= mxc_scc_dt_ids,
+	},
+};
+
+module_platform_driver(mxc_scc_driver);
+MODULE_AUTHOR("Steffen Trumtrar <[e-mail]>");
+MODULE_DESCRIPTION("Freescale i.MX25 SCC Crypto driver");
+MODULE_LICENSE("GPL v2");