[RESEND PATCH v3 5/6] dmaengine: stm32-dma: add support to trigger STM32 MDMA

Amelie Delaunay
2022-08-29T15:48:36Z

STM32 MDMA can be triggered by STM32 DMA channels transfer complete.
The "request line number" triggering STM32 MDMA is the STM32 DMAMUX channel
id set by stm32-dmamux driver in dma_spec->args[3].

stm32-dma driver fills the struct stm32_dma_mdma_config used to configure
the MDMA with struct dma_slave_config .peripheral_config/.peripheral_size.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
---
drivers/dma/stm32-dma.c | 47 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 6aa281561f38..4891a1767e5a 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -140,6 +140,7 @@
#define STM32_DMA_THRESHOLD_FTR_MASK GENMASK(1, 0)
#define STM32_DMA_DIRECT_MODE_MASK BIT(2)
#define STM32_DMA_ALT_ACK_MODE_MASK BIT(4)
+#define STM32_DMA_MDMA_STREAM_ID_MASK GENMASK(19, 16)

enum stm32_dma_width {
STM32_DMA_BYTE,
@@ -193,6 +194,19 @@ struct stm32_dma_desc {
struct stm32_dma_sg_req sg_req[];
};

+/**
+ * struct stm32_dma_mdma_config - STM32 DMA MDMA configuration
+ * @stream_id: DMA request to trigger STM32 MDMA transfer
+ * @ifcr: DMA interrupt flag clear register address,
+ * used by STM32 MDMA to clear DMA Transfer Complete flag
+ * @tcf: DMA Transfer Complete flag
+ */
+struct stm32_dma_mdma_config {
+ u32 stream_id;
+ u32 ifcr;
+ u32 tcf;
+};
+
struct stm32_dma_chan {
struct virt_dma_chan vchan;
bool config_init;
@@ -207,6 +221,8 @@ struct stm32_dma_chan {
u32 mem_burst;
u32 mem_width;
enum dma_status status;
+ bool trig_mdma;
+ struct stm32_dma_mdma_config mdma_config;
};

struct stm32_dma_device {
@@ -386,6 +402,13 @@ static int stm32_dma_slave_config(struct dma_chan *c,

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

+ /* Check if user is requesting DMA to trigger STM32 MDMA */
+ if (config->peripheral_size) {
+ config->peripheral_config = &chan->mdma_config;
+ config->peripheral_size = sizeof(chan->mdma_config);
+ chan->trig_mdma = true;
+ }
+
chan->config_init = true;

return 0;
@@ -561,6 +584,10 @@ static void stm32_dma_start_transfer(struct stm32_dma_chan *chan)
sg_req = &chan->desc->sg_req[chan->next_sg];
reg = &sg_req->chan_reg;

+ /* When DMA triggers STM32 MDMA, DMA Transfer Complete is managed by STM32 MDMA */
+ if (chan->trig_mdma && chan->dma_sconfig.direction != DMA_MEM_TO_DEV)
+ reg->dma_scr &= ~STM32_DMA_SCR_TCIE;
+
reg->dma_scr &= ~STM32_DMA_SCR_EN;
stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
stm32_dma_write(dmadev, STM32_DMA_SPAR(chan->id), reg->dma_spar);
@@ -710,6 +737,8 @@ static void stm32_dma_handle_chan_done(struct stm32_dma_chan *chan, u32 scr)

if (chan->desc->cyclic) {
vchan_cyclic_callback(&chan->desc->vdesc);
+ if (chan->trig_mdma)
+ return;
stm32_dma_sg_inc(chan);
/* cyclic while CIRC/DBM disable => post resume reconfiguration needed */
if (!(scr & (STM32_DMA_SCR_CIRC | STM32_DMA_SCR_DBM)))
@@ -1085,6 +1114,10 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
else
chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;

+ /* Activate Double Buffer Mode if DMA triggers STM32 MDMA and more than 1 sg */
+ if (chan->trig_mdma && sg_len > 1)
+ chan->chan_reg.dma_scr |= STM32_DMA_SCR_DBM;
+
for_each_sg(sgl, sg, sg_len, i) {
ret = stm32_dma_set_xfer_param(chan, direction, &buswidth,
sg_dma_len(sg),
@@ -1106,6 +1139,8 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
desc->sg_req[i].chan_reg.dma_sm0ar = sg_dma_address(sg);
desc->sg_req[i].chan_reg.dma_sm1ar = sg_dma_address(sg);
+ if (chan->trig_mdma)
+ desc->sg_req[i].chan_reg.dma_sm1ar += sg_dma_len(sg);
desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
}

@@ -1193,8 +1228,11 @@ static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
desc->sg_req[i].chan_reg.dma_sm0ar = buf_addr;
desc->sg_req[i].chan_reg.dma_sm1ar = buf_addr;
+ if (chan->trig_mdma)
+ desc->sg_req[i].chan_reg.dma_sm1ar += period_len;
desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
- buf_addr += period_len;
+ if (!chan->trig_mdma)
+ buf_addr += period_len;
}

desc->num_sgs = num_periods;
@@ -1476,6 +1514,7 @@ static void stm32_dma_set_config(struct stm32_dma_chan *chan,
chan->threshold = STM32_DMA_FIFO_THRESHOLD_NONE;
if (FIELD_GET(STM32_DMA_ALT_ACK_MODE_MASK, cfg->features))
chan->chan_reg.dma_scr |= STM32_DMA_SCR_TRBUFF;
+ chan->mdma_config.stream_id = FIELD_GET(STM32_DMA_MDMA_STREAM_ID_MASK, cfg->features);
}

static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
@@ -1615,6 +1654,12 @@ static int stm32_dma_probe(struct platform_device *pdev)
chan->id = i;
chan->vchan.desc_free = stm32_dma_desc_free;
vchan_init(&chan->vchan, dd);
+
+ chan->mdma_config.ifcr = res->start;
+ chan->mdma_config.ifcr += STM32_DMA_IFCR(chan->id);
+
+ chan->mdma_config.tcf = STM32_DMA_TCI;
+ chan->mdma_config.tcf <<= STM32_DMA_FLAGS_SHIFT(chan->id);
}

ret = dma_async_device_register(dd);
--
2.25.1