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 <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/omap-aes-gcm.c

···
 
 	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

···
 			      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);
-		scatterwalk_start(&dd->out_walk, dd->out_sg);
+		if (out_sg_len)
+			scatterwalk_start(&dd->out_walk, dd->out_sg);
 
 		/* Enable DATAIN interrupt and let it take
 		   care of the rest */
···
 
 	/* No callback necessary */
 	tx_in->callback_param = dd;
+	tx_in->callback = NULL;
 
 	/* OUT */
-	ret = dmaengine_slave_config(dd->dma_lch_out, &cfg);
-	if (ret) {
-		dev_err(dd->dev, "can't configure OUT dmaengine slave: %d\n",
-			ret);
-		return ret;
-	}
+	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",
+				ret);
+			return ret;
+		}
 
-	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) {
-		dev_err(dd->dev, "OUT prep_slave_sg() failed\n");
-		return -EINVAL;
+		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) {
+			dev_err(dd->dev, "OUT prep_slave_sg() failed\n");
+			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);
-	dmaengine_submit(tx_out);
+	if (tx_out)
+		dmaengine_submit(tx_out);
 
 	dma_async_issue_pending(dd->dma_lch_in);
-	dma_async_issue_pending(dd->dma_lch_out);
+	if (out_sg_len)
+		dma_async_issue_pending(dd->dma_lch_out);
 
 	/* start DMA */
 	dd->pdata->trigger(dd, dd->total);
···
 			return -EINVAL;
 		}
 
-		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");
-			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) {
+				dev_err(dd->dev, "dma_map_sg() error\n");
+				return -EINVAL;
+			}
 		}
 	}
 
···
 				 dd->out_sg_len);
 	if (err && !dd->pio_only) {
 		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);
+		if (dd->out_sg_len)
+			dma_unmap_sg(dd->dev, dd->out_sg, dd->out_sg_len,
+				     DMA_FROM_DEVICE);
 	}
 
 	return err;