linux-kernel - [PATCH 03/12] bcm2835-dma: Add NO_WAIT_RESP, DMA_WIDE_SOURCE and DMA_WIDE

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Date: Sun,  4 Feb 2024 07:59:31 +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>,
	Andrea della Porta <andrea.porta@...e.com>
Subject: [PATCH 03/12] bcm2835-dma: Add NO_WAIT_RESP, DMA_WIDE_SOURCE and DMA_WIDE_DEST flag

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

Use bit 27 of the dreq value (the second cell of the DT DMA descriptor)
to request that the WAIT_RESP bit is not set.

Use (reserved) bits 24 and 25 of the dreq value
(the second cell of the DT DMA descriptor) to request
that wide source reads or wide dest writes are required

Cc: Dom Cobley <popcornmix@...il.com>
Cc: Phil Elwell <phil@...pberrypi.com>
Signed-off-by: Andrea della Porta <andrea.porta@...e.com>
---
 drivers/dma/bcm2835-dma.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 11c6bf7d8a4b..36bad198b655 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -163,6 +163,21 @@ struct bcm2835_desc {
 #define BCM2835_DMA_WAIT(x)	((x & 31) << 21) /* add DMA-wait cycles */
 #define BCM2835_DMA_NO_WIDE_BURSTS BIT(26) /* no 2 beat write bursts */
 
+/* A fake bit to request that the driver doesn't set the WAIT_RESP bit. */
+#define BCM2835_DMA_NO_WAIT_RESP BIT(27)
+#define WAIT_RESP(x) (((x) & BCM2835_DMA_NO_WAIT_RESP) ? \
+		      0 : BCM2835_DMA_WAIT_RESP)
+
+/* A fake bit to request that the driver requires wide reads */
+#define BCM2835_DMA_WIDE_SOURCE BIT(24)
+#define WIDE_SOURCE(x) (((x) & BCM2835_DMA_WIDE_SOURCE) ? \
+		      BCM2835_DMA_S_WIDTH : 0)
+
+/* A fake bit to request that the driver requires wide writes */
+#define BCM2835_DMA_WIDE_DEST BIT(25)
+#define WIDE_DEST(x) (((x) & BCM2835_DMA_WIDE_DEST) ? \
+		      BCM2835_DMA_D_WIDTH : 0)
+
 /* debug register bits */
 #define BCM2835_DMA_DEBUG_LAST_NOT_SET_ERR	BIT(0)
 #define BCM2835_DMA_DEBUG_FIFO_ERR		BIT(1)
@@ -913,8 +928,9 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_memcpy(
 {
 	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 	struct bcm2835_desc *d;
-	u32 info = BCM2835_DMA_D_INC | BCM2835_DMA_S_INC;
-	u32 extra = BCM2835_DMA_INT_EN | BCM2835_DMA_WAIT_RESP;
+	u32 info = BCM2835_DMA_D_INC | BCM2835_DMA_S_INC |
+		   WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
+	u32 extra = BCM2835_DMA_INT_EN;
 	size_t max_len = bcm2835_dma_max_frame_length(c);
 	size_t frames;
 
@@ -944,7 +960,8 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
 	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 	struct bcm2835_desc *d;
 	dma_addr_t src = 0, dst = 0;
-	u32 info = BCM2835_DMA_WAIT_RESP;
+	u32 info = WAIT_RESP(c->dreq) |
+		   WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
 	u32 extra = BCM2835_DMA_INT_EN;
 	size_t frames;
 
@@ -1006,7 +1023,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
 	struct bcm2835_desc *d;
 	dma_addr_t src, dst;
-	u32 info = BCM2835_DMA_WAIT_RESP;
+	u32 info = WAIT_RESP(c->dreq) | WIDE_SOURCE(c->dreq) | WIDE_DEST(c->dreq);
 	u32 extra = 0;
 	size_t max_len = bcm2835_dma_max_frame_length(c);
 	size_t frames;
-- 
2.41.0