crypto: omap-aes-gcm - fix failure with assocdata only

If we only have assocdata with an omap-aes-gcm, it currently just
completes it directly without passing it over to the crypto HW. This
produces wrong results.

Fix by passing the request down to the crypto HW, and fix the DMA
support code to accept a case where we don't expect any output data.
In the case where only assocdata is provided, it just passes through
the accelerator and provides authentication results, without any
encrypted/decrypted buffer via DMA.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-aes-gcm.c

@@ -244,7 +244,7 @@ static int omap_aes_gcm_handle_queue(struct omap_aes_dev *dd,
 
 	err = omap_aes_write_ctrl(dd);
 	if (!err) {
-		if (dd->in_sg_len && dd->out_sg_len)
+		if (dd->in_sg_len)
 			err = omap_aes_crypt_dma_start(dd);
 		else
 			omap_aes_gcm_dma_out_callback(dd);

drivers/crypto/omap-aes.c

@@ -269,12 +269,13 @@ static int omap_aes_crypt_dma(struct omap_aes_dev *dd,
 			      struct scatterlist *out_sg,
 			      int in_sg_len, int out_sg_len)
 {
-	struct dma_async_tx_descriptor *tx_in, *tx_out;
+	struct dma_async_tx_descriptor *tx_in, *tx_out = NULL, *cb_desc;
 	struct dma_slave_config cfg;
 	int ret;
 
 	if (dd->pio_only) {
 		scatterwalk_start(&dd->in_walk, dd->in_sg);
+		if (out_sg_len)
 			scatterwalk_start(&dd->out_walk, dd->out_sg);
 
 		/* Enable DATAIN interrupt and let it take
@@ -312,8 +313,10 @@ static int omap_aes_crypt_dma(struct omap_aes_dev *dd,
 
 	/* No callback necessary */
 	tx_in->callback_param = dd;
+	tx_in->callback = NULL;
 
 	/* OUT */
+	if (out_sg_len) {
 		ret = dmaengine_slave_config(dd->dma_lch_out, &cfg);
 		if (ret) {
 			dev_err(dd->dev, "can't configure OUT dmaengine slave: %d\n",
@@ -321,7 +324,8 @@ static int omap_aes_crypt_dma(struct omap_aes_dev *dd,
 			return ret;
 		}
 
-	tx_out = dmaengine_prep_slave_sg(dd->dma_lch_out, out_sg, out_sg_len,
+		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) {
@@ -329,16 +333,24 @@ static int omap_aes_crypt_dma(struct omap_aes_dev *dd,
 			return -EINVAL;
 		}
 
+		cb_desc = tx_out;
+	} else {
+		cb_desc = tx_in;
+	}
+
 	if (dd->flags & FLAGS_GCM)
-		tx_out->callback = omap_aes_gcm_dma_out_callback;
+		cb_desc->callback = omap_aes_gcm_dma_out_callback;
 	else
-		tx_out->callback = omap_aes_dma_out_callback;
-	tx_out->callback_param = dd;
+		cb_desc->callback = omap_aes_dma_out_callback;
+	cb_desc->callback_param = dd;
+
 
 	dmaengine_submit(tx_in);
+	if (tx_out)
 		dmaengine_submit(tx_out);
 
 	dma_async_issue_pending(dd->dma_lch_in);
+	if (out_sg_len)
 		dma_async_issue_pending(dd->dma_lch_out);
 
 	/* start DMA */
@@ -361,6 +373,7 @@ int omap_aes_crypt_dma_start(struct omap_aes_dev *dd)
 			return -EINVAL;
 		}
 
+		if (dd->out_sg_len) {
 			err = dma_map_sg(dd->dev, dd->out_sg, dd->out_sg_len,
 					 DMA_FROM_DEVICE);
 			if (!err) {
@@ -368,11 +381,13 @@ int omap_aes_crypt_dma_start(struct omap_aes_dev *dd)
 				return -EINVAL;
 			}
 		}
+	}
 
 	err = omap_aes_crypt_dma(dd, dd->in_sg, dd->out_sg, dd->in_sg_len,
 				 dd->out_sg_len);
 	if (err && !dd->pio_only) {
 		dma_unmap_sg(dd->dev, dd->in_sg, dd->in_sg_len, DMA_TO_DEVICE);
+		if (dd->out_sg_len)
 			dma_unmap_sg(dd->dev, dd->out_sg, dd->out_sg_len,
 				     DMA_FROM_DEVICE);
 	}