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

Dave Stevenson
2024-05-24T18:27:59Z

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.stevenson@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