[RESEND PATCH v3 6/6] dmaengine: stm32-mdma: add support to be triggered by STM32 DMA

Amelie Delaunay
2022-08-29T15:48:34Z

STM32 MDMA can be triggered by STM32 DMA channels transfer complete.

In case of non-null struct dma_slave_config .peripheral_size, it means the
DMA client wants the DMA to trigger the MDMA.

stm32-mdma driver gets the request id, the mask_addr, and the mask_data in
struct stm32_mdma_dma_config passed by DMA with struct dma_slave_config
.peripheral_config/.peripheral_size.

Then, as DMA is configured in Double-Buffer mode, and MDMA channel will
transfer data from/to SRAM to/from DDR, then bursts are optimized.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
---
drivers/dma/stm32-mdma.c | 70 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 69 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index b11927ed4367..e28acbcb53f4 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -199,6 +199,7 @@ struct stm32_mdma_chan_config {
u32 transfer_config;
u32 mask_addr;
u32 mask_data;
+ bool m2m_hw; /* True when MDMA is triggered by STM32 DMA */
};

struct stm32_mdma_hwdesc {
@@ -227,6 +228,12 @@ struct stm32_mdma_desc {
struct stm32_mdma_desc_node node[];
};

+struct stm32_mdma_dma_config {
+ u32 request; /* STM32 DMA channel stream id, triggering MDMA */
+ u32 cmar; /* STM32 DMA interrupt flag clear register address */
+ u32 cmdr; /* STM32 DMA Transfer Complete flag */
+};
+
struct stm32_mdma_chan {
struct virt_dma_chan vchan;
struct dma_pool *desc_pool;
@@ -539,13 +546,23 @@ static int stm32_mdma_set_xfer_param(struct stm32_mdma_chan *chan,
dst_addr = chan->dma_config.dst_addr;

/* Set device data size */
+ if (chan_config->m2m_hw)
+ dst_addr_width = stm32_mdma_get_max_width(dst_addr, buf_len,
+ STM32_MDMA_MAX_BUF_LEN);
dst_bus_width = stm32_mdma_get_width(chan, dst_addr_width);
if (dst_bus_width < 0)
return dst_bus_width;
ctcr &= ~STM32_MDMA_CTCR_DSIZE_MASK;
ctcr |= STM32_MDMA_CTCR_DSIZE(dst_bus_width);
+ if (chan_config->m2m_hw) {
+ ctcr &= ~STM32_MDMA_CTCR_DINCOS_MASK;
+ ctcr |= STM32_MDMA_CTCR_DINCOS(dst_bus_width);
+ }

/* Set device burst value */
+ if (chan_config->m2m_hw)
+ dst_maxburst = STM32_MDMA_MAX_BUF_LEN / dst_addr_width;
+
dst_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
dst_maxburst,
dst_addr_width);
@@ -588,13 +605,24 @@ static int stm32_mdma_set_xfer_param(struct stm32_mdma_chan *chan,
src_addr = chan->dma_config.src_addr;

/* Set device data size */
+ if (chan_config->m2m_hw)
+ src_addr_width = stm32_mdma_get_max_width(src_addr, buf_len,
+ STM32_MDMA_MAX_BUF_LEN);
+
src_bus_width = stm32_mdma_get_width(chan, src_addr_width);
if (src_bus_width < 0)
return src_bus_width;
ctcr &= ~STM32_MDMA_CTCR_SSIZE_MASK;
ctcr |= STM32_MDMA_CTCR_SSIZE(src_bus_width);
+ if (chan_config->m2m_hw) {
+ ctcr &= ~STM32_MDMA_CTCR_SINCOS_MASK;
+ ctcr |= STM32_MDMA_CTCR_SINCOS(src_bus_width);
+ }

/* Set device burst value */
+ if (chan_config->m2m_hw)
+ src_maxburst = STM32_MDMA_MAX_BUF_LEN / src_addr_width;
+
src_best_burst = stm32_mdma_get_best_burst(buf_len, tlen,
src_maxburst,
src_addr_width);
@@ -702,11 +730,15 @@ static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
{
struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
struct dma_slave_config *dma_config = &chan->dma_config;
+ struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
struct scatterlist *sg;
dma_addr_t src_addr, dst_addr;
- u32 ccr, ctcr, ctbr;
+ u32 m2m_hw_period, ccr, ctcr, ctbr;
int i, ret = 0;

+ if (chan_config->m2m_hw)
+ m2m_hw_period = sg_dma_len(sgl);
+
for_each_sg(sgl, sg, sg_len, i) {
if (sg_dma_len(sg) > STM32_MDMA_MAX_BLOCK_LEN) {
dev_err(chan2dev(chan), "Invalid block len\n");
@@ -716,6 +748,8 @@ static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
if (direction == DMA_MEM_TO_DEV) {
src_addr = sg_dma_address(sg);
dst_addr = dma_config->dst_addr;
+ if (chan_config->m2m_hw && (i & 1))
+ dst_addr += m2m_hw_period;
ret = stm32_mdma_set_xfer_param(chan, direction, &ccr,
&ctcr, &ctbr, src_addr,
sg_dma_len(sg));
@@ -723,6 +757,8 @@ static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
src_addr);
} else {
src_addr = dma_config->src_addr;
+ if (chan_config->m2m_hw && (i & 1))
+ src_addr += m2m_hw_period;
dst_addr = sg_dma_address(sg);
ret = stm32_mdma_set_xfer_param(chan, direction, &ccr,
&ctcr, &ctbr, dst_addr,
@@ -755,6 +791,7 @@ stm32_mdma_prep_slave_sg(struct dma_chan *c, struct scatterlist *sgl,
unsigned long flags, void *context)
{
struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+ struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
struct stm32_mdma_desc *desc;
int i, ret;

@@ -777,6 +814,21 @@ stm32_mdma_prep_slave_sg(struct dma_chan *c, struct scatterlist *sgl,
if (ret < 0)
goto xfer_setup_err;

+ /*
+ * In case of M2M HW transfer triggered by STM32 DMA, we do not have to clear the
+ * transfer complete flag by hardware in order to let the CPU rearm the STM32 DMA
+ * with the next sg element and update some data in dmaengine framework.
+ */
+ if (chan_config->m2m_hw && direction == DMA_MEM_TO_DEV) {
+ struct stm32_mdma_hwdesc *hwdesc;
+
+ for (i = 0; i < sg_len; i++) {
+ hwdesc = desc->node[i].hwdesc;
+ hwdesc->cmar = 0;
+ hwdesc->cmdr = 0;
+ }
+ }
+
desc->cyclic = false;

return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
@@ -798,6 +850,7 @@ stm32_mdma_prep_dma_cyclic(struct dma_chan *c, dma_addr_t buf_addr,
struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
struct dma_slave_config *dma_config = &chan->dma_config;
+ struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
struct stm32_mdma_desc *desc;
dma_addr_t src_addr, dst_addr;
u32 ccr, ctcr, ctbr, count;
@@ -858,8 +911,12 @@ stm32_mdma_prep_dma_cyclic(struct dma_chan *c, dma_addr_t buf_addr,
if (direction == DMA_MEM_TO_DEV) {
src_addr = buf_addr + i * period_len;
dst_addr = dma_config->dst_addr;
+ if (chan_config->m2m_hw && (i & 1))
+ dst_addr += period_len;
} else {
src_addr = dma_config->src_addr;
+ if (chan_config->m2m_hw && (i & 1))
+ src_addr += period_len;
dst_addr = buf_addr + i * period_len;
}

@@ -1244,6 +1301,17 @@ static int stm32_mdma_slave_config(struct dma_chan *c,

memcpy(&chan->dma_config, config, sizeof(*config));

+ /* Check if user is requesting STM32 DMA to trigger MDMA */
+ if (config->peripheral_size) {
+ struct stm32_mdma_dma_config *mdma_config;
+
+ mdma_config = (struct stm32_mdma_dma_config *)chan->dma_config.peripheral_config;
+ chan->chan_config.request = mdma_config->request;
+ chan->chan_config.mask_addr = mdma_config->cmar;
+ chan->chan_config.mask_data = mdma_config->cmdr;
+ chan->chan_config.m2m_hw = true;
+ }
+
return 0;
}

--
2.25.1