[PATCH 09/18] dmaengine: bcm2835: Add function to handle DMA mapping

[Dave Stevenson]

The code handling DMA mapping is currently incorrect and
needs a sequence of fixups.
Move the mapping out into a separate function and structure
to allow for those fixes to be applied more cleanly.

Signed-off-by: Dave Stevenson <dave.steven...@raspberrypi.com>
---
 drivers/dma/bcm2835-dma.c | 46 ++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index aefaa1f01d7f..ef1d95bae84e 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -65,6 +65,10 @@ struct bcm2835_cb_entry {
        dma_addr_t paddr;
 };
 
+struct bcm2835_dma_chan_map {
+       dma_addr_t addr;
+};
+
 struct bcm2835_chan {
        struct virt_dma_chan vc;
 
@@ -74,6 +78,7 @@ struct bcm2835_chan {
        int ch;
        struct bcm2835_desc *desc;
        struct dma_pool *cb_pool;
+       struct bcm2835_dma_chan_map map;
 
        void __iomem *chan_base;
        int irq_number;
@@ -268,6 +273,19 @@ static inline bool need_dst_incr(enum 
dma_transfer_direction direction)
        }
 
        return false;
+};
+
+static int bcm2835_dma_map_slave_addr(struct dma_chan *chan,
+                                     phys_addr_t dev_addr,
+                                     size_t dev_size,
+                                     enum dma_data_direction dev_dir)
+{
+       struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+       struct bcm2835_dma_chan_map *map = &c->map;
+
+       map->addr = dev_addr;
+
+       return 0;
 }
 
 static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc)
@@ -734,13 +752,19 @@ static struct dma_async_tx_descriptor 
*bcm2835_dma_prep_slave_sg(
        }
 
        if (direction == DMA_DEV_TO_MEM) {
-               if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+               if (bcm2835_dma_map_slave_addr(chan, c->cfg.src_addr,
+                                              c->cfg.src_addr_width,
+                                              DMA_TO_DEVICE))
                        return NULL;
-               src = c->cfg.src_addr;
+
+               src = c->map.addr;
        } else {
-               if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+               if (bcm2835_dma_map_slave_addr(chan, c->cfg.dst_addr,
+                                              c->cfg.dst_addr_width,
+                                              DMA_FROM_DEVICE))
                        return NULL;
-               dst = c->cfg.dst_addr;
+
+               dst = c->map.addr;
        }
 
        /* count frames in sg list */
@@ -795,14 +819,20 @@ static struct dma_async_tx_descriptor 
*bcm2835_dma_prep_dma_cyclic(
                              __func__, buf_len, period_len);
 
        if (direction == DMA_DEV_TO_MEM) {
-               if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+               if (bcm2835_dma_map_slave_addr(chan, c->cfg.src_addr,
+                                              c->cfg.src_addr_width,
+                                              DMA_TO_DEVICE))
                        return NULL;
-               src = c->cfg.src_addr;
+
+               src = c->map.addr;
                dst = buf_addr;
        } else {
-               if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+               if (bcm2835_dma_map_slave_addr(chan, c->cfg.dst_addr,
+                                              c->cfg.dst_addr_width,
+                                              DMA_FROM_DEVICE))
                        return NULL;
-               dst = c->cfg.dst_addr;
+
+               dst = c->map.addr;
                src = buf_addr;
        }
 
-- 
2.34.1