linux-kernel - [PATCH 05/12] bcm2835-dma: Derive slave DMA addresses correctly

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Date: Sun,  4 Feb 2024 07:59:33 +0100
From: Andrea della Porta <andrea.porta@...e.com>
To: Vinod Koul <vkoul@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	dmaengine@...r.kernel.org,
	linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Maxime Ripard <maxime@...no.tech>,
	Dom Cobley <popcornmix@...il.com>,
	Phil Elwell <phil@...pberrypi.com>
Subject: [PATCH 05/12] bcm2835-dma: Derive slave DMA addresses correctly

From: Phil Elwell <phil@...pberrypi.com>

Slave addresses for DMA are meant to be supplied as physical addresses
(contrary to what struct snd_dmaengine_dai_dma_data does). It is up to
the DMA controller driver to perform the translation based on its own
view of the world, as described in Device Tree.

Now that the Pi Device Trees have the correct peripheral mappings,
replace the hacky address munging with phys_to_dma().

Signed-off-by: Phil Elwell <phil@...pberrypi.com>
---
 drivers/dma/bcm2835-dma.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 237dcdb8d726..077812eda609 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -18,6 +18,7 @@
  *	Copyright 2012 Marvell International Ltd.
  */
 #include <linux/dmaengine.h>
+#include <linux/dma-direct.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
 #include <linux/err.h>
@@ -980,22 +981,12 @@ 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)
 			return NULL;
-		src = c->cfg.src_addr;
-		/*
-		 * One would think it ought to be possible to get the physical
-		 * to dma address mapping information from the dma-ranges DT
-		 * property, but I've not found a way yet that doesn't involve
-		 * open-coding the whole thing.
-		 */
-		if (c->is_40bit_channel)
-			src |= 0x400000000ull;
+		src = phys_to_dma(chan->device->dev, c->cfg.src_addr);
 		info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
 	} else {
 		if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
 			return NULL;
-		dst = c->cfg.dst_addr;
-		if (c->is_40bit_channel)
-			dst |= 0x400000000ull;
+		dst = phys_to_dma(chan->device->dev, c->cfg.dst_addr);
 		info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
 	}
 
@@ -1064,17 +1055,13 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 	if (direction == DMA_DEV_TO_MEM) {
 		if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
 			return NULL;
-		src = c->cfg.src_addr;
-		if (c->is_40bit_channel)
-			src |= 0x400000000ull;
+		src = phys_to_dma(chan->device->dev, c->cfg.src_addr);
 		dst = buf_addr;
 		info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
 	} else {
 		if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
 			return NULL;
-		dst = c->cfg.dst_addr;
-		if (c->is_40bit_channel)
-			dst |= 0x400000000ull;
+		dst = phys_to_dma(chan->device->dev, c->cfg.dst_addr);
 		src = buf_addr;
 		info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
 
-- 
2.41.0