crypto: omap-sham - add support functions for sg based data handling

Currently omap-sham uses a huge internal buffer for caching data, and
pushing this out to the DMA as large chunks. This, unfortunately,
doesn't work too well with the export/import functionality required
for ahash algorithms, and must be changed towards more scatterlist
centric approach.

This patch adds support functions for (mostly) scatterlist based data
handling. omap_sham_prepare_request() prepares a scatterlist for DMA
transfer to SHA crypto accelerator. This requires checking the data /
offset / length alignment of the data, splitting the data to SHA block
size granularity, and adding any remaining data back to the buffer.
With this patch, the code doesn't actually go live yet, the support code
will be taken properly into use with additional patches that modify the
SHA driver functionality itself.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-sham.c

@@ -112,6 +112,8 @@
 #define FLAGS_DMA_READY		6
 #define FLAGS_AUTO_XOR		7
 #define FLAGS_BE32_SHA1		8
+#define FLAGS_SGS_COPIED	9
+#define FLAGS_SGS_ALLOCED	10
 /* context flags */
 #define FLAGS_FINUP		16
 #define FLAGS_SG		17
@@ -151,8 +153,10 @@ struct omap_sham_reqctx {
 
 	/* walk state */
 	struct scatterlist	*sg;
+	struct scatterlist	sgl[2];
 	struct scatterlist	sgl_tmp;
 	unsigned int		offset;	/* offset in current sg */
+	int			sg_len;
 	unsigned int		total;	/* total request */
 
 	u8			buffer[0] OMAP_ALIGNED;
@@ -223,6 +227,7 @@ struct omap_sham_dev {
 	struct dma_chan		*dma_lch;
 	struct tasklet_struct	done_task;
 	u8			polling_mode;
+	u8			xmit_buf[BUFLEN];
 
 	unsigned long		flags;
 	struct crypto_queue	queue;
@@ -626,6 +631,260 @@ static int omap_sham_xmit_dma(struct omap_sham_dev *dd, dma_addr_t dma_addr,
 	return -EINPROGRESS;
 }
 
+static int omap_sham_copy_sg_lists(struct omap_sham_reqctx *ctx,
+				   struct scatterlist *sg, int bs, int new_len)
+{
+	int n = sg_nents(sg);
+	struct scatterlist *tmp;
+	int offset = ctx->offset;
+
+	if (ctx->bufcnt)
+		n++;
+
+	ctx->sg = kmalloc_array(n, sizeof(*sg), GFP_KERNEL);
+	if (!ctx->sg)
+		return -ENOMEM;
+
+	sg_init_table(ctx->sg, n);
+
+	tmp = ctx->sg;
+
+	ctx->sg_len = 0;
+
+	if (ctx->bufcnt) {
+		sg_set_buf(tmp, ctx->dd->xmit_buf, ctx->bufcnt);
+		tmp = sg_next(tmp);
+		ctx->sg_len++;
+	}
+
+	while (sg && new_len) {
+		int len = sg->length - offset;
+
+		if (offset) {
+			offset -= sg->length;
+			if (offset < 0)
+				offset = 0;
+		}
+
+		if (new_len < len)
+			len = new_len;
+
+		if (len > 0) {
+			new_len -= len;
+			sg_set_page(tmp, sg_page(sg), len, sg->offset);
+			if (new_len <= 0)
+				sg_mark_end(tmp);
+			tmp = sg_next(tmp);
+			ctx->sg_len++;
+		}
+
+		sg = sg_next(sg);
+	}
+
+	set_bit(FLAGS_SGS_ALLOCED, &ctx->dd->flags);
+
+	ctx->bufcnt = 0;
+
+	return 0;
+}
+
+static int omap_sham_copy_sgs(struct omap_sham_reqctx *ctx,
+			      struct scatterlist *sg, int bs, int new_len)
+{
+	int pages;
+	void *buf;
+	int len;
+
+	len = new_len + ctx->bufcnt;
+
+	pages = get_order(ctx->total);
+
+	buf = (void *)__get_free_pages(GFP_ATOMIC, pages);
+	if (!buf) {
+		pr_err("Couldn't allocate pages for unaligned cases.\n");
+		return -ENOMEM;
+	}
+
+	if (ctx->bufcnt)
+		memcpy(buf, ctx->dd->xmit_buf, ctx->bufcnt);
+
+	scatterwalk_map_and_copy(buf + ctx->bufcnt, sg, ctx->offset,
+				 ctx->total - ctx->bufcnt, 0);
+	sg_init_table(ctx->sgl, 1);
+	sg_set_buf(ctx->sgl, buf, len);
+	ctx->sg = ctx->sgl;
+	set_bit(FLAGS_SGS_COPIED, &ctx->dd->flags);
+	ctx->sg_len = 1;
+	ctx->bufcnt = 0;
+	ctx->offset = 0;
+
+	return 0;
+}
+
+static int omap_sham_align_sgs(struct scatterlist *sg,
+			       int nbytes, int bs, bool final,
+			       struct omap_sham_reqctx *rctx)
+{
+	int n = 0;
+	bool aligned = true;
+	bool list_ok = true;
+	struct scatterlist *sg_tmp = sg;
+	int new_len;
+	int offset = rctx->offset;
+
+	if (!sg || !sg->length || !nbytes)
+		return 0;
+
+	new_len = nbytes;
+
+	if (offset)
+		list_ok = false;
+
+	if (final)
+		new_len = DIV_ROUND_UP(new_len, bs) * bs;
+	else
+		new_len = new_len / bs * bs;
+
+	while (nbytes > 0 && sg_tmp) {
+		n++;
+
+		if (offset < sg_tmp->length) {
+			if (!IS_ALIGNED(offset + sg_tmp->offset, 4)) {
+				aligned = false;
+				break;
+			}
+
+			if (!IS_ALIGNED(sg_tmp->length - offset, bs)) {
+				aligned = false;
+				break;
+			}
+		}
+
+		if (offset) {
+			offset -= sg_tmp->length;
+			if (offset < 0) {
+				nbytes += offset;
+				offset = 0;
+			}
+		} else {
+			nbytes -= sg_tmp->length;
+		}
+
+		sg_tmp = sg_next(sg_tmp);
+
+		if (nbytes < 0) {
+			list_ok = false;
+			break;
+		}
+	}
+
+	if (!aligned)
+		return omap_sham_copy_sgs(rctx, sg, bs, new_len);
+	else if (!list_ok)
+		return omap_sham_copy_sg_lists(rctx, sg, bs, new_len);
+
+	rctx->sg_len = n;
+	rctx->sg = sg;
+
+	return 0;
+}
+
+static int omap_sham_prepare_request(struct ahash_request *req, bool update)
+{
+	struct omap_sham_reqctx *rctx = ahash_request_ctx(req);
+	int bs;
+	int ret;
+	int nbytes;
+	bool final = rctx->flags & BIT(FLAGS_FINUP);
+	int xmit_len, hash_later;
+
+	if (!req)
+		return 0;
+
+	bs = get_block_size(rctx);
+
+	if (update)
+		nbytes = req->nbytes;
+	else
+		nbytes = 0;
+
+	rctx->total = nbytes + rctx->bufcnt;
+
+	if (!rctx->total)
+		return 0;
+
+	if (nbytes && (!IS_ALIGNED(rctx->bufcnt, bs))) {
+		int len = bs - rctx->bufcnt % bs;
+
+		if (len > nbytes)
+			len = nbytes;
+		scatterwalk_map_and_copy(rctx->buffer + rctx->bufcnt, req->src,
+					 0, len, 0);
+		rctx->bufcnt += len;
+		nbytes -= len;
+		rctx->offset = len;
+	}
+
+	if (rctx->bufcnt)
+		memcpy(rctx->dd->xmit_buf, rctx->buffer, rctx->bufcnt);
+
+	ret = omap_sham_align_sgs(req->src, nbytes, bs, final, rctx);
+	if (ret)
+		return ret;
+
+	xmit_len = rctx->total;
+
+	if (!IS_ALIGNED(xmit_len, bs)) {
+		if (final)
+			xmit_len = DIV_ROUND_UP(xmit_len, bs) * bs;
+		else
+			xmit_len = xmit_len / bs * bs;
+	}
+
+	hash_later = rctx->total - xmit_len;
+	if (hash_later < 0)
+		hash_later = 0;
+
+	if (rctx->bufcnt && nbytes) {
+		/* have data from previous operation and current */
+		sg_init_table(rctx->sgl, 2);
+		sg_set_buf(rctx->sgl, rctx->dd->xmit_buf, rctx->bufcnt);
+
+		sg_chain(rctx->sgl, 2, req->src);
+
+		rctx->sg = rctx->sgl;
+
+		rctx->sg_len++;
+	} else if (rctx->bufcnt) {
+		/* have buffered data only */
+		sg_init_table(rctx->sgl, 1);
+		sg_set_buf(rctx->sgl, rctx->dd->xmit_buf, xmit_len);
+
+		rctx->sg = rctx->sgl;
+
+		rctx->sg_len = 1;
+	}
+
+	if (hash_later) {
+		if (req->nbytes) {
+			scatterwalk_map_and_copy(rctx->buffer, req->src,
+						 req->nbytes - hash_later,
+						 hash_later, 0);
+		} else {
+			memcpy(rctx->buffer, rctx->buffer + xmit_len,
+			       hash_later);
+		}
+		rctx->bufcnt = hash_later;
+	} else {
+		rctx->bufcnt = 0;
+	}
+
+	if (!final)
+		rctx->total = xmit_len;
+
+	return 0;
+}
+
 static size_t omap_sham_append_buffer(struct omap_sham_reqctx *ctx,
 				const u8 *data, size_t length)
 {
@@ -1040,6 +1299,10 @@ retry:
 	dd->req = req;
 	ctx = ahash_request_ctx(req);
 
+	err = omap_sham_prepare_request(NULL, ctx->op == OP_UPDATE);
+	if (err)
+		goto err1;
+
 	dev_dbg(dd->dev, "handling new req, op: %lu, nbytes: %d\n",
 						ctx->op, req->nbytes);