firmware: qcom_scm: fix bogous abuse of dma-direct internals

As far as the device is concerned the dma address is the physical
address.  There is no need to convert it to a physical address,
especially not using dma-direct internals that are not available
to drivers and which will interact badly with IOMMUs.  Last but not
least the commit introducing it claimed to just fix a type issue,
but actually changed behavior.

Fixes: 6e37ccf ("firmware: qcom_scm: Use proper types for dma mappings")
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20200414123136.441454-1-hch@lst.de
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/firmware/qcom_scm.c

@@ -6,7 +6,6 @@
 #include <linux/init.h>
 #include <linux/cpumask.h>
 #include <linux/export.h>
-#include <linux/dma-direct.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <linux/types.h>
@@ -806,8 +805,7 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
 	struct qcom_scm_mem_map_info *mem_to_map;
 	phys_addr_t mem_to_map_phys;
 	phys_addr_t dest_phys;
-	phys_addr_t ptr_phys;
-	dma_addr_t ptr_dma;
+	dma_addr_t ptr_phys;
 	size_t mem_to_map_sz;
 	size_t dest_sz;
 	size_t src_sz;
@@ -824,10 +822,9 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
 	ptr_sz = ALIGN(src_sz, SZ_64) + ALIGN(mem_to_map_sz, SZ_64) +
 			ALIGN(dest_sz, SZ_64);
 
-	ptr = dma_alloc_coherent(__scm->dev, ptr_sz, &ptr_dma, GFP_KERNEL);
+	ptr = dma_alloc_coherent(__scm->dev, ptr_sz, &ptr_phys, GFP_KERNEL);
 	if (!ptr)
 		return -ENOMEM;
-	ptr_phys = dma_to_phys(__scm->dev, ptr_dma);
 
 	/* Fill source vmid detail */
 	src = ptr;
@@ -855,7 +852,7 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
 
 	ret = __qcom_scm_assign_mem(__scm->dev, mem_to_map_phys, mem_to_map_sz,
 				    ptr_phys, src_sz, dest_phys, dest_sz);
-	dma_free_coherent(__scm->dev, ptr_sz, ptr, ptr_dma);
+	dma_free_coherent(__scm->dev, ptr_sz, ptr, ptr_phys);
 	if (ret) {
 		dev_err(__scm->dev,
 			"Assign memory protection call failed %d\n", ret);