dma-mapping: MMIO mappings still need phys_to_dma

The new concept of MMIO DMA addresses is used to indicate things with
fixed addresses - hardware registers, not movable pages. As such it is
reasonable to bypass the SWIOTLB mapping logic, but not any CPU<->DMA
address translation that has been configured by Device Tree. Doing so
will break any drives using (possibly indirectly) dma_map_resource
for register addresses where ther is a non-identity mapping between
CPU and DMA addresses. A good example of this is the SDHOST MMC
interface on BCM283x SoCs.

Fix the bug by reinstating the phys_to_dma call in the MMIO code path.

N.B. The upstream SDHOST driver (drivers/mmc/host/bcm2835.c) is not
affected by this bug because it pulls bus/DMA addresses directly out
of Device Tree.

See: #7136
Fixes: e53d29f ("dma-mapping: convert dma_direct_*map_page to be phys_addr_t based")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Author: pelwell

kernel/dma/direct.h

@@ -94,7 +94,7 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev,
 	}
 
 	if (attrs & DMA_ATTR_MMIO) {
-		dma_addr = phys;
+		dma_addr = phys_to_dma(dev, phys);
 		if (unlikely(!dma_capable(dev, dma_addr, size, false)))
 			goto err_overflow;
 	} else {