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From: Dave Stevenson <dave.stevenson@raspberrypi.com>
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Cc: devicetree@vger.kernel.org,
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	Dave Stevenson <dave.stevenson@raspberrypi.com>
Subject: [PATCH 11/18] dmaengine: bcm2835: Use dma_map_resource to map addresses
Date: Fri, 24 May 2024 19:26:55 +0100
Message-Id: <20240524182702.1317935-12-dave.stevenson@raspberrypi.com>
In-Reply-To: <20240524182702.1317935-1-dave.stevenson@raspberrypi.com>
References: <20240524182702.1317935-1-dave.stevenson@raspberrypi.com>
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There is a need to account for dma-ranges and iommus in the
dma mapping process, and the public API for handling that is
dma_map_resource.

Add support for mapping addresses to the DMA driver.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/dma/bcm2835-dma.c | 46 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 9531c0b82071..e48008b06716 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -67,6 +67,10 @@ struct bcm2835_cb_entry {
 
 struct bcm2835_dma_chan_map {
 	dma_addr_t addr;
+	enum dma_data_direction dir;
+
+	phys_addr_t slave_addr;
+	unsigned int xfer_size;
 };
 
 struct bcm2835_chan {
@@ -294,12 +298,44 @@ static int bcm2835_dma_map_slave_addr(struct dma_chan *chan,
 		return 0;
 	}
 
-	/*
-	 * This path will be updated to handle new clients, but currently should
-	 * never be used.
-	 */
+	if (dev_size != DMA_SLAVE_BUSWIDTH_4_BYTES)
+		return -EIO;
+
+	/* Reuse current map if possible. */
+	if (dev_addr == map->slave_addr &&
+	    dev_size == map->xfer_size &&
+	    dev_dir == map->dir)
+		return 0;
+
+	/* Remove old mapping if present. */
+	if (map->xfer_size) {
+		dev_dbg(chan->device->dev, "chan: unmap %zx@%pap to %pad dir: %s\n",
+			dev_size, &dev_addr, &map->addr,
+			dev_dir == DMA_TO_DEVICE ? "DMA_TO_DEVICE" : "DMA_FROM_DEVICE");
+		dma_unmap_resource(chan->device->dev, map->addr,
+				   map->xfer_size, map->dir, 0);
+	}
+	map->xfer_size = 0;
 
-	return -EINVAL;
+	/* Create new slave address map. */
+	map->addr = dma_map_resource(chan->device->dev, dev_addr, dev_size,
+				     dev_dir, 0);
+
+	if (dma_mapping_error(chan->device->dev, map->addr)) {
+		dev_err(chan->device->dev, "chan: failed to map %zx@%pap",
+			dev_size, &dev_addr);
+		return -EIO;
+	}
+
+	dev_dbg(chan->device->dev, "chan: map %zx@%pap to %pad dir: %s\n",
+		dev_size, &dev_addr, &map->addr,
+		dev_dir == DMA_TO_DEVICE ? "DMA_TO_DEVICE" : "DMA_FROM_DEVICE");
+
+	map->slave_addr = dev_addr;
+	map->xfer_size = dev_size;
+	map->dir = dev_dir;
+
+	return 0;
 }
 
 static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc)
-- 
2.34.1