crypto: omap-aes - Simplify DMA usage by using direct SGs

In early version of this driver, assumptions were made such as DMA layer
requires contiguous buffers etc. Due to this, new buffers were allocated,
mapped and used for DMA. These assumptions are no longer true and DMAEngine
scatter-gather DMA doesn't have such requirements. We simply the DMA operations
by directly using the scatter-gather buffers provided by the crypto layer
instead of creating our own.

Lot of logic that handled DMA'ing only X number of bytes of the total, or as
much as fitted into a 3rd party buffer is removed and is no longer required.

Also, good performance improvement of atleast ~20% seen with encrypting a
buffer size of 8K (1800 ops/sec vs 1400 ops/sec).  Improvement will be higher
for much larger blocks though such benchmarking is left as an exercise for the
reader.  Also DMA usage is much more simplified and coherent with rest of the
code.
Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-aes.c

@@ -475,22 +475,14 @@ static int sg_copy(struct scatterlist **sg, size_t *offset, void *buf,
 }
 
 static int omap_aes_crypt_dma(struct crypto_tfm *tfm,
-		struct scatterlist *in_sg, struct scatterlist *out_sg)
+		struct scatterlist *in_sg, struct scatterlist *out_sg,
+		int in_sg_len, int out_sg_len)
 {
 	struct omap_aes_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct omap_aes_dev *dd = ctx->dd;
 	struct dma_async_tx_descriptor *tx_in, *tx_out;
 	struct dma_slave_config cfg;
-	dma_addr_t dma_addr_in = sg_dma_address(in_sg);
-	int ret, length = sg_dma_len(in_sg);
-
-	pr_debug("len: %d\n", length);
-
-	dd->dma_size = length;
-
-	if (!(dd->flags & FLAGS_FAST))
-		dma_sync_single_for_device(dd->dev, dma_addr_in, length,
-					   DMA_TO_DEVICE);
+	int ret;
 
 	memset(&cfg, 0, sizeof(cfg));
 
@@ -509,7 +501,7 @@ static int omap_aes_crypt_dma(struct crypto_tfm *tfm,
 		return ret;
 	}
 
-	tx_in = dmaengine_prep_slave_sg(dd->dma_lch_in, in_sg, 1,
+	tx_in = dmaengine_prep_slave_sg(dd->dma_lch_in, in_sg, in_sg_len,
 					DMA_MEM_TO_DEV,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!tx_in) {
@@ -528,7 +520,7 @@ static int omap_aes_crypt_dma(struct crypto_tfm *tfm,
 		return ret;
 	}
 
-	tx_out = dmaengine_prep_slave_sg(dd->dma_lch_out, out_sg, 1,
+	tx_out = dmaengine_prep_slave_sg(dd->dma_lch_out, out_sg, out_sg_len,
 					DMA_DEV_TO_MEM,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!tx_out) {
@@ -546,7 +538,7 @@ static int omap_aes_crypt_dma(struct crypto_tfm *tfm,
 	dma_async_issue_pending(dd->dma_lch_out);
 
 	/* start DMA */
-	dd->pdata->trigger(dd, length);
+	dd->pdata->trigger(dd, dd->total);
 
 	return 0;
 }
@@ -555,93 +547,28 @@ static int omap_aes_crypt_dma_start(struct omap_aes_dev *dd)
 {
 	struct crypto_tfm *tfm = crypto_ablkcipher_tfm(
 					crypto_ablkcipher_reqtfm(dd->req));
-	int err, fast = 0, in, out;
-	size_t count;
-	dma_addr_t addr_in, addr_out;
-	struct scatterlist *in_sg, *out_sg;
-	int len32;
+	int err;
 
 	pr_debug("total: %d\n", dd->total);
 
-	if (sg_is_last(dd->in_sg) && sg_is_last(dd->out_sg)) {
-		/* check for alignment */
-		in = IS_ALIGNED((u32)dd->in_sg->offset, sizeof(u32));
-		out = IS_ALIGNED((u32)dd->out_sg->offset, sizeof(u32));
-
-		fast = in && out;
-	}
-
-	if (fast)  {
-		count = min(dd->total, sg_dma_len(dd->in_sg));
-		count = min(count, sg_dma_len(dd->out_sg));
-
-		if (count != dd->total) {
-			pr_err("request length != buffer length\n");
-			return -EINVAL;
-		}
-
-		pr_debug("fast\n");
-
-		err = dma_map_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE);
+	err = dma_map_sg(dd->dev, dd->in_sg, dd->in_sg_len, DMA_TO_DEVICE);
 	if (!err) {
 		dev_err(dd->dev, "dma_map_sg() error\n");
 		return -EINVAL;
 	}
 
-		err = dma_map_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE);
+	err = dma_map_sg(dd->dev, dd->out_sg, dd->out_sg_len, DMA_FROM_DEVICE);
 	if (!err) {
 		dev_err(dd->dev, "dma_map_sg() error\n");
-			dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE);
 		return -EINVAL;
 	}
 
-		addr_in = sg_dma_address(dd->in_sg);
-		addr_out = sg_dma_address(dd->out_sg);
-
-		in_sg = dd->in_sg;
-		out_sg = dd->out_sg;
-
-		dd->flags |= FLAGS_FAST;
-
-	} else {
-		/* use cache buffers */
-		count = sg_copy(&dd->in_sg, &dd->in_offset, dd->buf_in,
-				 dd->buflen, dd->total, 0);
-
-		len32 = DIV_ROUND_UP(count, DMA_MIN) * DMA_MIN;
-
-		/*
-		 * The data going into the AES module has been copied
-		 * to a local buffer and the data coming out will go
-		 * into a local buffer so set up local SG entries for
-		 * both.
-		 */
-		sg_init_table(&dd->in_sgl, 1);
-		dd->in_sgl.offset = dd->in_offset;
-		sg_dma_len(&dd->in_sgl) = len32;
-		sg_dma_address(&dd->in_sgl) = dd->dma_addr_in;
-
-		sg_init_table(&dd->out_sgl, 1);
-		dd->out_sgl.offset = dd->out_offset;
-		sg_dma_len(&dd->out_sgl) = len32;
-		sg_dma_address(&dd->out_sgl) = dd->dma_addr_out;
-
-		in_sg = &dd->in_sgl;
-		out_sg = &dd->out_sgl;
-
-		addr_in = dd->dma_addr_in;
-		addr_out = dd->dma_addr_out;
-
-		dd->flags &= ~FLAGS_FAST;
-
-	}
-
-	dd->total -= count;
-
-	err = omap_aes_crypt_dma(tfm, in_sg, out_sg);
+	err = omap_aes_crypt_dma(tfm, dd->in_sg, dd->out_sg, dd->in_sg_len,
+				 dd->out_sg_len);
 	if (err) {
-		dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE);
-		dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_TO_DEVICE);
+		dma_unmap_sg(dd->dev, dd->in_sg, dd->in_sg_len, DMA_TO_DEVICE);
+		dma_unmap_sg(dd->dev, dd->out_sg, dd->out_sg_len,
+			     DMA_FROM_DEVICE);
 	}
 
 	return err;
@@ -661,7 +588,6 @@ static void omap_aes_finish_req(struct omap_aes_dev *dd, int err)
 static int omap_aes_crypt_dma_stop(struct omap_aes_dev *dd)
 {
 	int err = 0;
-	size_t count;
 
 	pr_debug("total: %d\n", dd->total);
 
@@ -670,21 +596,8 @@ static int omap_aes_crypt_dma_stop(struct omap_aes_dev *dd)
 	dmaengine_terminate_all(dd->dma_lch_in);
 	dmaengine_terminate_all(dd->dma_lch_out);
 
-	if (dd->flags & FLAGS_FAST) {
-		dma_unmap_sg(dd->dev, dd->out_sg, 1, DMA_FROM_DEVICE);
-		dma_unmap_sg(dd->dev, dd->in_sg, 1, DMA_TO_DEVICE);
-	} else {
-		dma_sync_single_for_device(dd->dev, dd->dma_addr_out,
-					   dd->dma_size, DMA_FROM_DEVICE);
-
-		/* copy data */
-		count = sg_copy(&dd->out_sg, &dd->out_offset, dd->buf_out,
-				 dd->buflen, dd->dma_size, 1);
-		if (count != dd->dma_size) {
-			err = -EINVAL;
-			pr_err("not all data converted: %u\n", count);
-		}
-	}
+	dma_unmap_sg(dd->dev, dd->in_sg, dd->in_sg_len, DMA_TO_DEVICE);
+	dma_unmap_sg(dd->dev, dd->out_sg, dd->out_sg_len, DMA_FROM_DEVICE);
 
 	return err;
 }
@@ -754,21 +667,11 @@ static int omap_aes_handle_queue(struct omap_aes_dev *dd,
 static void omap_aes_done_task(unsigned long data)
 {
 	struct omap_aes_dev *dd = (struct omap_aes_dev *)data;
-	int err;
-
-	pr_debug("enter\n");
-
-	err = omap_aes_crypt_dma_stop(dd);
 
-	err = dd->err ? : err;
+	pr_debug("enter done_task\n");
 
-	if (dd->total && !err) {
-		err = omap_aes_crypt_dma_start(dd);
-		if (!err)
-			return; /* DMA started. Not fininishing. */
-	}
-
-	omap_aes_finish_req(dd, err);
+	omap_aes_crypt_dma_stop(dd);
+	omap_aes_finish_req(dd, 0);
 	omap_aes_handle_queue(dd, NULL);
 
 	pr_debug("exit\n");