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

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Date: Fri, 24 May 2024 19:26:53 +0100
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Vinod Koul <vkoul@...nel.org>,
	Maxime Ripard <mripard@...nel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Mark Brown <broonie@...nel.org>,
	Christoph Hellwig <hch@....de>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Robin Murphy <robin.murphy@....com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Vladimir Murzin <vladimir.murzin@....com>,
	Phil Elwell <phil@...pberrypi.com>,
	Stefan Wahren <wahrenst@....net>,
	Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc: devicetree@...r.kernel.org,
	linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-mmc@...r.kernel.org,
	linux-spi@...r.kernel.org,
	iommu@...ts.linux.dev,
	linux-sound@...r.kernel.org,
	Dave Stevenson <dave.stevenson@...pberrypi.com>
Subject: [PATCH 09/18] dmaengine: bcm2835: Add function to handle DMA mapping

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@...pberrypi.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