crypto: ccp - Add a module parameter to control registration for DMA

The CCP driver is able to act as a DMA engine. Add a module parameter that
allows this feature to be enabled/disabled.
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/ccp/ccp-dmaengine.c

@@ -2,7 +2,7 @@
 /*
  * AMD Cryptographic Coprocessor (CCP) driver
  *
- * Copyright (C) 2016,2017 Advanced Micro Devices, Inc.
+ * Copyright (C) 2016,2019 Advanced Micro Devices, Inc.
  *
  * Author: Gary R Hook <gary.hook@amd.com>
  */
@@ -35,6 +35,10 @@ static unsigned int dma_chan_attr = CCP_DMA_DFLT;
 module_param(dma_chan_attr, uint, 0444);
 MODULE_PARM_DESC(dma_chan_attr, "Set DMA channel visibility: 0 (default) = device defaults, 1 = make private, 2 = make public");
 
+static unsigned int dmaengine = 1;
+module_param(dmaengine, uint, 0444);
+MODULE_PARM_DESC(dmaengine, "Register services with the DMA subsystem (any non-zero value, default: 1)");
+
 static unsigned int ccp_get_dma_chan_attr(struct ccp_device *ccp)
 {
 	switch (dma_chan_attr) {
@@ -637,6 +641,9 @@ int ccp_dmaengine_register(struct ccp_device *ccp)
 	unsigned int i;
 	int ret;
 
+	if (!dmaengine)
+		return 0;
+
 	ccp->ccp_dma_chan = devm_kcalloc(ccp->dev, ccp->cmd_q_count,
 					 sizeof(*(ccp->ccp_dma_chan)),
 					 GFP_KERNEL);
@@ -740,6 +747,9 @@ void ccp_dmaengine_unregister(struct ccp_device *ccp)
 {
 	struct dma_device *dma_dev = &ccp->dma_dev;
 
+	if (!dmaengine)
+		return;
+
 	dma_async_device_unregister(dma_dev);
 
 	kmem_cache_destroy(ccp->dma_desc_cache);