[PATCH 04/18] dmaengine: bcm2835: move CB info generation into separate function

Dave Stevenson
2024-05-24T18:27:54Z

From: Stefan Wahren <stefan.wahren@i2se.com>

Actually the generation of the Control Block info follows some simple
rules. So handle this with a separate function to avoid open coding
for every DMA operation. Another advantage is that we can easier
introduce other platforms with different info bits.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
drivers/dma/bcm2835-dma.c | 50 +++++++++++++++++++++++++--------------
1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 528c4593b45a..7cef7ff89575 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -201,6 +201,34 @@ static inline struct bcm2835_desc *to_bcm2835_dma_desc(
return container_of(t, struct bcm2835_desc, vd.tx);
}

+static u32 bcm2835_dma_prepare_cb_info(struct bcm2835_chan *c,
+ enum dma_transfer_direction direction,
+ bool zero_page)
+{
+ u32 result;
+
+ if (direction == DMA_MEM_TO_MEM)
+ return BCM2835_DMA_D_INC | BCM2835_DMA_S_INC;
+
+ result = BCM2835_DMA_WAIT_RESP;
+
+ /* Setup DREQ channel */
+ if (c->dreq != 0)
+ result |= BCM2835_DMA_PER_MAP(c->dreq);
+
+ if (direction == DMA_DEV_TO_MEM) {
+ result |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
+ } else {
+ result |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
+
+ /* non-lite channels can write zeroes w/o accessing memory */
+ if (zero_page && !c->is_lite_channel)
+ result |= BCM2835_DMA_S_IGNORE;
+ }
+
+ return result;
+}
+
static void bcm2835_dma_free_cb_chain(struct bcm2835_desc *desc)
{
size_t i;
@@ -615,7 +643,7 @@ 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 info = bcm2835_dma_prepare_cb_info(c, DMA_MEM_TO_MEM, false);
u32 extra = BCM2835_DMA_INT_EN | BCM2835_DMA_WAIT_RESP;
size_t max_len = bcm2835_dma_max_frame_length(c);
size_t frames;
@@ -646,7 +674,7 @@ 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 = bcm2835_dma_prepare_cb_info(c, direction, false);
u32 extra = BCM2835_DMA_INT_EN;
size_t frames;

@@ -656,19 +684,14 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
return NULL;
}

- if (c->dreq != 0)
- info |= BCM2835_DMA_PER_MAP(c->dreq);
-
if (direction == DMA_DEV_TO_MEM) {
if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
src = 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;
- info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
}

/* count frames in sg list */
@@ -698,7 +721,8 @@ 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 = bcm2835_dma_prepare_cb_info(c, direction,
+ buf_addr == od->zero_page);
u32 extra = 0;
size_t max_len = bcm2835_dma_max_frame_length(c);
size_t frames;
@@ -729,26 +753,16 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
"%s: buffer_length (%zd) is not a multiple of period_len (%zd)\n",
__func__, buf_len, period_len);

- /* Setup DREQ channel */
- if (c->dreq != 0)
- info |= BCM2835_DMA_PER_MAP(c->dreq);
-
if (direction == DMA_DEV_TO_MEM) {
if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
return NULL;
src = 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;
src = buf_addr;
- info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
-
- /* non-lite channels can write zeroes w/o accessing memory */
- if (buf_addr == od->zero_page && !c->is_lite_channel)
- info |= BCM2835_DMA_S_IGNORE;
}

/* calculate number of frames */
--
2.34.1