linux/drivers/crypto/bfin_crc.c

/*
 * Cryptographic API.
 *
 * Support Blackfin CRC HW acceleration.
 *
 * Copyright 2012 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/err.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/unaligned/access_ok.h>
#include <linux/crypto.h>
#include <linux/cryptohash.h>
#include <crypto/scatterwalk.h>
#include <crypto/algapi.h>
#include <crypto/hash.h>
#include <crypto/internal/hash.h>

#include <asm/blackfin.h>
#include <asm/bfin_crc.h>
#include <asm/dma.h>
#include <asm/portmux.h>

#define CRC_CCRYPTO_QUEUE_LENGTH	5

#define DRIVER_NAME "bfin-hmac-crc"
#define CHKSUM_DIGEST_SIZE      4
#define CHKSUM_BLOCK_SIZE       1

#define CRC_MAX_DMA_DESC	100

#define CRC_CRYPTO_STATE_UPDATE		1
#define CRC_CRYPTO_STATE_FINALUPDATE	2
#define CRC_CRYPTO_STATE_FINISH		3

struct bfin_crypto_crc {
	struct list_head	list;
	struct device		*dev;
	spinlock_t		lock;

	int			irq;
	int			dma_ch;
	u32			poly;
	volatile struct crc_register *regs;

	struct ahash_request	*req; /* current request in operation */
	struct dma_desc_array	*sg_cpu; /* virt addr of sg dma descriptors */
	dma_addr_t		sg_dma; /* phy addr of sg dma descriptors */
	u8			*sg_mid_buf;

	struct tasklet_struct	done_task;
	struct crypto_queue	queue; /* waiting requests */

	u8			busy:1; /* crc device in operation flag */
};

static struct bfin_crypto_crc_list {
	struct list_head	dev_list;
	spinlock_t		lock;
} crc_list;

struct bfin_crypto_crc_reqctx {
	struct bfin_crypto_crc	*crc;

	unsigned int		total;	/* total request bytes */
	size_t			sg_buflen; /* bytes for this update */
	unsigned int		sg_nents;
	struct scatterlist	*sg; /* sg list head for this update*/
	struct scatterlist	bufsl[2]; /* chained sg list */

	size_t			bufnext_len;
	size_t			buflast_len;
	u8			bufnext[CHKSUM_DIGEST_SIZE]; /* extra bytes for next udpate */
	u8			buflast[CHKSUM_DIGEST_SIZE]; /* extra bytes from last udpate */

	u8			flag;
};

struct bfin_crypto_crc_ctx {
	struct bfin_crypto_crc	*crc;
	u32			key;
};


/*
 * derive number of elements in scatterlist
 */
static int sg_count(struct scatterlist *sg_list)
{
	struct scatterlist *sg = sg_list;
	int sg_nents = 1;

	if (sg_list == NULL)
		return 0;

	while (!sg_is_last(sg)) {
		sg_nents++;
		sg = scatterwalk_sg_next(sg);
	}

	return sg_nents;
}

/*
 * get element in scatter list by given index
 */
static struct scatterlist *sg_get(struct scatterlist *sg_list, unsigned int nents,
				unsigned int index)
{
	struct scatterlist *sg = NULL;
	int i;

	for_each_sg(sg_list, sg, nents, i)
		if (i == index)
			break;

	return sg;
}

static int bfin_crypto_crc_init_hw(struct bfin_crypto_crc *crc, u32 key)
{
	crc->regs->datacntrld = 0;
	crc->regs->control = MODE_CALC_CRC << OPMODE_OFFSET;
	crc->regs->curresult = key;

	/* setup CRC interrupts */
	crc->regs->status = CMPERRI | DCNTEXPI;
	crc->regs->intrenset = CMPERRI | DCNTEXPI;

	return 0;
}

static int bfin_crypto_crc_init(struct ahash_request *req)
{
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct bfin_crypto_crc_ctx *crc_ctx = crypto_ahash_ctx(tfm);
	struct bfin_crypto_crc_reqctx *ctx = ahash_request_ctx(req);
	struct bfin_crypto_crc *crc;

	dev_dbg(ctx->crc->dev, "crc_init\n");
	spin_lock_bh(&crc_list.lock);
	list_for_each_entry(crc, &crc_list.dev_list, list) {
		crc_ctx->crc = crc;
		break;
	}
	spin_unlock_bh(&crc_list.lock);

	if (sg_count(req->src) > CRC_MAX_DMA_DESC) {
		dev_dbg(ctx->crc->dev, "init: requested sg list is too big > %d\n",
			CRC_MAX_DMA_DESC);
		return -EINVAL;
	}

	ctx->crc = crc;
	ctx->bufnext_len = 0;
	ctx->buflast_len = 0;
	ctx->sg_buflen = 0;
	ctx->total = 0;
	ctx->flag = 0;

	/* init crc results */
	put_unaligned_le32(crc_ctx->key, req->result);

	dev_dbg(ctx->crc->dev, "init: digest size: %d\n",
		crypto_ahash_digestsize(tfm));

	return bfin_crypto_crc_init_hw(crc, crc_ctx->key);
}

static void bfin_crypto_crc_config_dma(struct bfin_crypto_crc *crc)
{
	struct scatterlist *sg;
	struct bfin_crypto_crc_reqctx *ctx = ahash_request_ctx(crc->req);
	int i = 0, j = 0;
	unsigned long dma_config;
	unsigned int dma_count;
	unsigned int dma_addr;
	unsigned int mid_dma_count = 0;
	int dma_mod;

	dma_map_sg(crc->dev, ctx->sg, ctx->sg_nents, DMA_TO_DEVICE);

	for_each_sg(ctx->sg, sg, ctx->sg_nents, j) {
		dma_config = DMAFLOW_ARRAY | RESTART | NDSIZE_3 | DMAEN | PSIZE_32;
		dma_addr = sg_dma_address(sg);
		/* deduce extra bytes in last sg */
		if (sg_is_last(sg))
			dma_count = sg_dma_len(sg) - ctx->bufnext_len;
		else
			dma_count = sg_dma_len(sg);

		if (mid_dma_count) {
			/* Append last middle dma buffer to 4 bytes with first
			   bytes in current sg buffer. Move addr of current
			   sg and deduce the length of current sg.
			 */
			memcpy(crc->sg_mid_buf +((i-1) << 2) + mid_dma_count,
				(void *)dma_addr,
				CHKSUM_DIGEST_SIZE - mid_dma_count);
			dma_addr += CHKSUM_DIGEST_SIZE - mid_dma_count;
			dma_count -= CHKSUM_DIGEST_SIZE - mid_dma_count;
		}
		/* chop current sg dma len to multiple of 32 bits */
		mid_dma_count = dma_count % 4;
		dma_count &= ~0x3;

		if (dma_addr % 4 == 0) {
			dma_config |= WDSIZE_32;
			dma_count >>= 2;
			dma_mod = 4;
		} else if (dma_addr % 2 == 0) {
			dma_config |= WDSIZE_16;
			dma_count >>= 1;
			dma_mod = 2;
		} else {
			dma_config |= WDSIZE_8;
			dma_mod = 1;
		}

		crc->sg_cpu[i].start_addr = dma_addr;
		crc->sg_cpu[i].cfg = dma_config;
		crc->sg_cpu[i].x_count = dma_count;
		crc->sg_cpu[i].x_modify = dma_mod;
		dev_dbg(crc->dev, "%d: crc_dma: start_addr:0x%lx, "
			"cfg:0x%lx, x_count:0x%lx, x_modify:0x%lx\n",
			i, crc->sg_cpu[i].start_addr,
			crc->sg_cpu[i].cfg, crc->sg_cpu[i].x_count,
			crc->sg_cpu[i].x_modify);
		i++;

		if (mid_dma_count) {
			/* copy extra bytes to next middle dma buffer */
			dma_config = DMAFLOW_ARRAY | RESTART | NDSIZE_3 |
				DMAEN | PSIZE_32 | WDSIZE_32;
			memcpy(crc->sg_mid_buf + (i << 2),
				(void *)(dma_addr + (dma_count << 2)),
				mid_dma_count);
			/* setup new dma descriptor for next middle dma */
			crc->sg_cpu[i].start_addr = dma_map_single(crc->dev,
					crc->sg_mid_buf + (i << 2),
					CHKSUM_DIGEST_SIZE, DMA_TO_DEVICE);
			crc->sg_cpu[i].cfg = dma_config;
			crc->sg_cpu[i].x_count = 1;
			crc->sg_cpu[i].x_modify = CHKSUM_DIGEST_SIZE;
			dev_dbg(crc->dev, "%d: crc_dma: start_addr:0x%lx, "
				"cfg:0x%lx, x_count:0x%lx, x_modify:0x%lx\n",
				i, crc->sg_cpu[i].start_addr,
				crc->sg_cpu[i].cfg, crc->sg_cpu[i].x_count,
				crc->sg_cpu[i].x_modify);
			i++;
		}
	}

	dma_config = DMAFLOW_ARRAY | RESTART | NDSIZE_3 | DMAEN | PSIZE_32 | WDSIZE_32;
	/* For final update req, append the buffer for next update as well*/
	if (ctx->bufnext_len && (ctx->flag == CRC_CRYPTO_STATE_FINALUPDATE ||
		ctx->flag == CRC_CRYPTO_STATE_FINISH)) {
		crc->sg_cpu[i].start_addr = dma_map_single(crc->dev, ctx->bufnext,
						CHKSUM_DIGEST_SIZE, DMA_TO_DEVICE);
		crc->sg_cpu[i].cfg = dma_config;
		crc->sg_cpu[i].x_count = 1;
		crc->sg_cpu[i].x_modify = CHKSUM_DIGEST_SIZE;
		dev_dbg(crc->dev, "%d: crc_dma: start_addr:0x%lx, "
			"cfg:0x%lx, x_count:0x%lx, x_modify:0x%lx\n",
			i, crc->sg_cpu[i].start_addr,
			crc->sg_cpu[i].cfg, crc->sg_cpu[i].x_count,
			crc->sg_cpu[i].x_modify);
		i++;
	}

	if (i == 0)
		return;

	/* Set the last descriptor to stop mode */
	crc->sg_cpu[i - 1].cfg &= ~(DMAFLOW | NDSIZE);
	crc->sg_cpu[i - 1].cfg |= DI_EN;
	set_dma_curr_desc_addr(crc->dma_ch, (unsigned long *)crc->sg_dma);
	set_dma_x_count(crc->dma_ch, 0);
	set_dma_x_modify(crc->dma_ch, 0);
	set_dma_config(crc->dma_ch, dma_config);
}

static int bfin_crypto_crc_handle_queue(struct bfin_crypto_crc *crc,
				  struct ahash_request *req)
{
	struct crypto_async_request *async_req, *backlog;
	struct bfin_crypto_crc_reqctx *ctx;
	struct scatterlist *sg;
	int ret = 0;
	int nsg, i, j;
	unsigned int nextlen;
	unsigned long flags;

	spin_lock_irqsave(&crc->lock, flags);
	if (req)
		ret = ahash_enqueue_request(&crc->queue, req);
	if (crc->busy) {
		spin_unlock_irqrestore(&crc->lock, flags);
		return ret;
	}
	backlog = crypto_get_backlog(&crc->queue);
	async_req = crypto_dequeue_request(&crc->queue);
	if (async_req)
		crc->busy = 1;
	spin_unlock_irqrestore(&crc->lock, flags);

	if (!async_req)
		return ret;

	if (backlog)
		backlog->complete(backlog, -EINPROGRESS);

	req = ahash_request_cast(async_req);
	crc->req = req;
	ctx = ahash_request_ctx(req);
	ctx->sg = NULL;
	ctx->sg_buflen = 0;
	ctx->sg_nents = 0;

	dev_dbg(crc->dev, "handling new req, flag=%u, nbytes: %d\n",
						ctx->flag, req->nbytes);

	if (ctx->flag == CRC_CRYPTO_STATE_FINISH) {
		if (ctx->bufnext_len == 0) {
			crc->busy = 0;
			return 0;
		}

		/* Pack last crc update buffer to 32bit */
		memset(ctx->bufnext + ctx->bufnext_len, 0,
				CHKSUM_DIGEST_SIZE - ctx->bufnext_len);
	} else {
		/* Pack small data which is less than 32bit to buffer for next update. */
		if (ctx->bufnext_len + req->nbytes < CHKSUM_DIGEST_SIZE) {
			memcpy(ctx->bufnext + ctx->bufnext_len,
				sg_virt(req->src), req->nbytes);
			ctx->bufnext_len += req->nbytes;
			if (ctx->flag == CRC_CRYPTO_STATE_FINALUPDATE &&
				ctx->bufnext_len) {
				goto finish_update;
			} else {
				crc->busy = 0;
				return 0;
			}
		}

		if (ctx->bufnext_len) {
			/* Chain in extra bytes of last update */
			ctx->buflast_len = ctx->bufnext_len;
			memcpy(ctx->buflast, ctx->bufnext, ctx->buflast_len);

			nsg = ctx->sg_buflen ? 2 : 1;
			sg_init_table(ctx->bufsl, nsg);
			sg_set_buf(ctx->bufsl, ctx->buflast, ctx->buflast_len);
			if (nsg > 1)
				scatterwalk_sg_chain(ctx->bufsl, nsg,
						req->src);
			ctx->sg = ctx->bufsl;
		} else
			ctx->sg = req->src;

		/* Chop crc buffer size to multiple of 32 bit */
		nsg = ctx->sg_nents = sg_count(ctx->sg);
		ctx->sg_buflen = ctx->buflast_len + req->nbytes;
		ctx->bufnext_len = ctx->sg_buflen % 4;
		ctx->sg_buflen &= ~0x3;

		if (ctx->bufnext_len) {
			/* copy extra bytes to buffer for next update */
			memset(ctx->bufnext, 0, CHKSUM_DIGEST_SIZE);
			nextlen = ctx->bufnext_len;
			for (i = nsg - 1; i >= 0; i--) {
				sg = sg_get(ctx->sg, nsg, i);
				j = min(nextlen, sg_dma_len(sg));
				memcpy(ctx->bufnext + nextlen - j,
					sg_virt(sg) + sg_dma_len(sg) - j, j);
				if (j == sg_dma_len(sg))
					ctx->sg_nents--;
				nextlen -= j;
				if (nextlen == 0)
					break;
			}
		}
	}

finish_update:
	if (ctx->bufnext_len && (ctx->flag == CRC_CRYPTO_STATE_FINALUPDATE ||
		ctx->flag == CRC_CRYPTO_STATE_FINISH))
		ctx->sg_buflen += CHKSUM_DIGEST_SIZE;

	/* set CRC data count before start DMA */
	crc->regs->datacnt = ctx->sg_buflen >> 2;

	/* setup and enable CRC DMA */
	bfin_crypto_crc_config_dma(crc);

	/* finally kick off CRC operation */
	crc->regs->control |= BLKEN;

	return -EINPROGRESS;
}

static int bfin_crypto_crc_update(struct ahash_request *req)
{
	struct bfin_crypto_crc_reqctx *ctx = ahash_request_ctx(req);

	if (!req->nbytes)
		return 0;

	dev_dbg(ctx->crc->dev, "crc_update\n");
	ctx->total += req->nbytes;
	ctx->flag = CRC_CRYPTO_STATE_UPDATE;

	return bfin_crypto_crc_handle_queue(ctx->crc, req);
}

static int bfin_crypto_crc_final(struct ahash_request *req)
{
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct bfin_crypto_crc_ctx *crc_ctx = crypto_ahash_ctx(tfm);
	struct bfin_crypto_crc_reqctx *ctx = ahash_request_ctx(req);

	dev_dbg(ctx->crc->dev, "crc_final\n");
	ctx->flag = CRC_CRYPTO_STATE_FINISH;
	crc_ctx->key = 0;

	return bfin_crypto_crc_handle_queue(ctx->crc, req);
}

static int bfin_crypto_crc_finup(struct ahash_request *req)
{
	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
	struct bfin_crypto_crc_ctx *crc_ctx = crypto_ahash_ctx(tfm);
	struct bfin_crypto_crc_reqctx *ctx = ahash_request_ctx(req);

	dev_dbg(ctx->crc->dev, "crc_finishupdate\n");
	ctx->total += req->nbytes;
	ctx->flag = CRC_CRYPTO_STATE_FINALUPDATE;
	crc_ctx->key = 0;

	return bfin_crypto_crc_handle_queue(ctx->crc, req);
}

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

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

	return bfin_crypto_crc_finup(req);
}

static int bfin_crypto_crc_setkey(struct crypto_ahash *tfm, const u8 *key,
			unsigned int keylen)
{
	struct bfin_crypto_crc_ctx *crc_ctx = crypto_ahash_ctx(tfm);

	dev_dbg(crc_ctx->crc->dev, "crc_setkey\n");
	if (keylen != CHKSUM_DIGEST_SIZE) {
		crypto_ahash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}

	crc_ctx->key = get_unaligned_le32(key);

	return 0;
}

static int bfin_crypto_crc_cra_init(struct crypto_tfm *tfm)
{
	struct bfin_crypto_crc_ctx *crc_ctx = crypto_tfm_ctx(tfm);

	crc_ctx->key = 0;
	crypto_ahash_set_reqsize(__crypto_ahash_cast(tfm),
				 sizeof(struct bfin_crypto_crc_reqctx));

	return 0;
}

static void bfin_crypto_crc_cra_exit(struct crypto_tfm *tfm)
{
}

static struct ahash_alg algs = {
	.init		= bfin_crypto_crc_init,
	.update		= bfin_crypto_crc_update,
	.final		= bfin_crypto_crc_final,
	.finup		= bfin_crypto_crc_finup,
	.digest		= bfin_crypto_crc_digest,
	.setkey		= bfin_crypto_crc_setkey,
	.halg.digestsize	= CHKSUM_DIGEST_SIZE,
	.halg.base	= {
		.cra_name		= "hmac(crc32)",
		.cra_driver_name	= DRIVER_NAME,
		.cra_priority		= 100,
		.cra_flags		= CRYPTO_ALG_TYPE_AHASH |
						CRYPTO_ALG_ASYNC,
		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
		.cra_ctxsize		= sizeof(struct bfin_crypto_crc_ctx),
		.cra_alignmask		= 3,
		.cra_module		= THIS_MODULE,
		.cra_init		= bfin_crypto_crc_cra_init,
		.cra_exit		= bfin_crypto_crc_cra_exit,
	}
};

static void bfin_crypto_crc_done_task(unsigned long data)
{
	struct bfin_crypto_crc *crc = (struct bfin_crypto_crc *)data;

	bfin_crypto_crc_handle_queue(crc, NULL);
}

static irqreturn_t bfin_crypto_crc_handler(int irq, void *dev_id)
{
	struct bfin_crypto_crc *crc = dev_id;

	if (crc->regs->status & DCNTEXP) {
		crc->regs->status = DCNTEXP;

		/* prepare results */
		put_unaligned_le32(crc->regs->result, crc->req->result);

		crc->regs->control &= ~BLKEN;
		crc->busy = 0;

		if (crc->req->base.complete)
			crc->req->base.complete(&crc->req->base, 0);

		tasklet_schedule(&crc->done_task);

		return IRQ_HANDLED;
	} else
		return IRQ_NONE;
}

#ifdef CONFIG_PM
/**
 *	bfin_crypto_crc_suspend - suspend crc device
 *	@pdev: device being suspended
 *	@state: requested suspend state
 */
static int bfin_crypto_crc_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct bfin_crypto_crc *crc = platform_get_drvdata(pdev);
	int i = 100000;

	while ((crc->regs->control & BLKEN) && --i)
		cpu_relax();

	if (i == 0)
		return -EBUSY;

	return 0;
}
#else
# define bfin_crypto_crc_suspend NULL
#endif

#define bfin_crypto_crc_resume NULL

/**
 *	bfin_crypto_crc_probe - Initialize module
 *
 */
static int bfin_crypto_crc_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct bfin_crypto_crc *crc;
	unsigned int timeout = 100000;
	int ret;

	crc = devm_kzalloc(dev, sizeof(*crc), GFP_KERNEL);
	if (!crc) {
		dev_err(&pdev->dev, "fail to malloc bfin_crypto_crc\n");
		return -ENOMEM;
	}

	crc->dev = dev;

	INIT_LIST_HEAD(&crc->list);
	spin_lock_init(&crc->lock);
	tasklet_init(&crc->done_task, bfin_crypto_crc_done_task, (unsigned long)crc);
	crypto_init_queue(&crc->queue, CRC_CCRYPTO_QUEUE_LENGTH);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
		return -ENOENT;
	}

	crc->regs = devm_ioremap_resource(dev, res);
	if (IS_ERR((void *)crc->regs)) {
		dev_err(&pdev->dev, "Cannot map CRC IO\n");
		return PTR_ERR((void *)crc->regs);
	}

	crc->irq = platform_get_irq(pdev, 0);
	if (crc->irq < 0) {
		dev_err(&pdev->dev, "No CRC DCNTEXP IRQ specified\n");
		return -ENOENT;
	}

	ret = devm_request_irq(dev, crc->irq, bfin_crypto_crc_handler,
			IRQF_SHARED, dev_name(dev), crc);
	if (ret) {
		dev_err(&pdev->dev, "Unable to request blackfin crc irq\n");
		return ret;
	}

	res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "No CRC DMA channel specified\n");
		return -ENOENT;
	}
	crc->dma_ch = res->start;

	ret = request_dma(crc->dma_ch, dev_name(dev));
	if (ret) {
		dev_err(&pdev->dev, "Unable to attach Blackfin CRC DMA channel\n");
		return ret;
	}

	crc->sg_cpu = dma_alloc_coherent(&pdev->dev, PAGE_SIZE, &crc->sg_dma, GFP_KERNEL);
	if (crc->sg_cpu == NULL) {
		ret = -ENOMEM;
		goto out_error_dma;
	}
	/*
	 * need at most CRC_MAX_DMA_DESC sg + CRC_MAX_DMA_DESC middle  +
	 * 1 last + 1 next dma descriptors
	 */
	crc->sg_mid_buf = (u8 *)(crc->sg_cpu + ((CRC_MAX_DMA_DESC + 1) << 1));

	crc->regs->control = 0;
	crc->regs->poly = crc->poly = (u32)pdev->dev.platform_data;

	while (!(crc->regs->status & LUTDONE) && (--timeout) > 0)
		cpu_relax();

	if (timeout == 0)
		dev_info(&pdev->dev, "init crc poly timeout\n");

	spin_lock(&crc_list.lock);
	list_add(&crc->list, &crc_list.dev_list);
	spin_unlock(&crc_list.lock);

	platform_set_drvdata(pdev, crc);

	ret = crypto_register_ahash(&algs);
	if (ret) {
		spin_lock(&crc_list.lock);
		list_del(&crc->list);
		spin_unlock(&crc_list.lock);
		dev_err(&pdev->dev, "Cann't register crypto ahash device\n");
		goto out_error_dma;
	}

	dev_info(&pdev->dev, "initialized\n");

	return 0;

out_error_dma:
	if (crc->sg_cpu)
		dma_free_coherent(&pdev->dev, PAGE_SIZE, crc->sg_cpu, crc->sg_dma);
	free_dma(crc->dma_ch);

	return ret;
}

/**
 *	bfin_crypto_crc_remove - Initialize module
 *
 */
static int bfin_crypto_crc_remove(struct platform_device *pdev)
{
	struct bfin_crypto_crc *crc = platform_get_drvdata(pdev);

	if (!crc)
		return -ENODEV;

	spin_lock(&crc_list.lock);
	list_del(&crc->list);
	spin_unlock(&crc_list.lock);

	crypto_unregister_ahash(&algs);
	tasklet_kill(&crc->done_task);
	free_dma(crc->dma_ch);

	return 0;
}

static struct platform_driver bfin_crypto_crc_driver = {
	.probe     = bfin_crypto_crc_probe,
	.remove    = bfin_crypto_crc_remove,
	.suspend   = bfin_crypto_crc_suspend,
	.resume    = bfin_crypto_crc_resume,
	.driver    = {
		.name  = DRIVER_NAME,
		.owner = THIS_MODULE,
	},
};

/**
 *	bfin_crypto_crc_mod_init - Initialize module
 *
 *	Checks the module params and registers the platform driver.
 *	Real work is in the platform probe function.
 */
static int __init bfin_crypto_crc_mod_init(void)
{
	int ret;

	pr_info("Blackfin hardware CRC crypto driver\n");

	INIT_LIST_HEAD(&crc_list.dev_list);
	spin_lock_init(&crc_list.lock);

	ret = platform_driver_register(&bfin_crypto_crc_driver);
	if (ret) {
		pr_info(KERN_ERR "unable to register driver\n");
		return ret;
	}

	return 0;
}

/**
 *	bfin_crypto_crc_mod_exit - Deinitialize module
 */
static void __exit bfin_crypto_crc_mod_exit(void)
{
	platform_driver_unregister(&bfin_crypto_crc_driver);
}

module_init(bfin_crypto_crc_mod_init);
module_exit(bfin_crypto_crc_mod_exit);

MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
MODULE_DESCRIPTION("Blackfin CRC hardware crypto driver");
MODULE_LICENSE("GPL");