[PATCH 2/2] dmaengine: stm32-dma: direct mode support through device tree
From: Amelie Delaunay
Date: Wed Apr 22 2020 - 06:31:03 EST
Direct mode or FIFO mode is computed by stm32-dma driver. Add a way for
the user to force direct mode, by setting bit 2 in the bitfield value
specifying DMA features in the device tree.
Signed-off-by: Amelie Delaunay <amelie.delaunay@xxxxxx>
---
drivers/dma/stm32-dma.c | 41 +++++++++++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 10 deletions(-)
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 0ddbaa4b4f0b..96ad1b3d24c6 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -117,6 +117,7 @@
#define STM32_DMA_FIFO_THRESHOLD_HALFFULL 0x01
#define STM32_DMA_FIFO_THRESHOLD_3QUARTERSFULL 0x02
#define STM32_DMA_FIFO_THRESHOLD_FULL 0x03
+#define STM32_DMA_FIFO_THRESHOLD_NONE 0x04
#define STM32_DMA_MAX_DATA_ITEMS 0xffff
/*
@@ -136,6 +137,9 @@
/* DMA Features */
#define STM32_DMA_THRESHOLD_FTR_MASK GENMASK(1, 0)
#define STM32_DMA_THRESHOLD_FTR_GET(n) ((n) & STM32_DMA_THRESHOLD_FTR_MASK)
+#define STM32_DMA_DIRECT_MODE_MASK BIT(2)
+#define STM32_DMA_DIRECT_MODE_GET(n) (((n) & STM32_DMA_DIRECT_MODE_MASK) \
+ >> 2)
enum stm32_dma_width {
STM32_DMA_BYTE,
@@ -281,6 +285,9 @@ static bool stm32_dma_fifo_threshold_is_allowed(u32 burst, u32 threshold,
{
u32 remaining;
+ if (threshold == STM32_DMA_FIFO_THRESHOLD_NONE)
+ return false;
+
if (width != DMA_SLAVE_BUSWIDTH_UNDEFINED) {
if (burst != 0) {
/*
@@ -302,6 +309,10 @@ static bool stm32_dma_fifo_threshold_is_allowed(u32 burst, u32 threshold,
static bool stm32_dma_is_burst_possible(u32 buf_len, u32 threshold)
{
+ /* If FIFO direct mode, burst is not possible */
+ if (threshold == STM32_DMA_FIFO_THRESHOLD_NONE)
+ return false;
+
/*
* Buffer or period length has to be aligned on FIFO depth.
* Otherwise bytes may be stuck within FIFO at buffer or period
@@ -657,6 +668,12 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
dev_dbg(chan2dev(chan), "FIFO over/underrun\n");
}
}
+ if (status & STM32_DMA_DMEI) {
+ stm32_dma_irq_clear(chan, STM32_DMA_DMEI);
+ status &= ~STM32_DMA_DMEI;
+ if (sfcr & STM32_DMA_SCR_DMEIE)
+ dev_dbg(chan2dev(chan), "Direct mode overrun\n");
+ }
if (status) {
stm32_dma_irq_clear(chan, status);
dev_err(chan2dev(chan), "DMA error: status=0x%08x\n", status);
@@ -692,13 +709,13 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
int src_bus_width, dst_bus_width;
int src_burst_size, dst_burst_size;
u32 src_maxburst, dst_maxburst, src_best_burst, dst_best_burst;
- u32 dma_scr, threshold;
+ u32 dma_scr, fifoth;
src_addr_width = chan->dma_sconfig.src_addr_width;
dst_addr_width = chan->dma_sconfig.dst_addr_width;
src_maxburst = chan->dma_sconfig.src_maxburst;
dst_maxburst = chan->dma_sconfig.dst_maxburst;
- threshold = chan->threshold;
+ fifoth = chan->threshold;
switch (direction) {
case DMA_MEM_TO_DEV:
@@ -710,7 +727,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
/* Set device burst size */
dst_best_burst = stm32_dma_get_best_burst(buf_len,
dst_maxburst,
- threshold,
+ fifoth,
dst_addr_width);
dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
@@ -718,7 +735,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
return dst_burst_size;
/* Set memory data size */
- src_addr_width = stm32_dma_get_max_width(buf_len, threshold);
+ src_addr_width = stm32_dma_get_max_width(buf_len, fifoth);
chan->mem_width = src_addr_width;
src_bus_width = stm32_dma_get_width(chan, src_addr_width);
if (src_bus_width < 0)
@@ -728,7 +745,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
src_maxburst = STM32_DMA_MAX_BURST;
src_best_burst = stm32_dma_get_best_burst(buf_len,
src_maxburst,
- threshold,
+ fifoth,
src_addr_width);
src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
if (src_burst_size < 0)
@@ -742,7 +759,8 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
/* Set FIFO threshold */
chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
- chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(threshold);
+ if (fifoth != STM32_DMA_FIFO_THRESHOLD_NONE)
+ chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(fifoth);
/* Set peripheral address */
chan->chan_reg.dma_spar = chan->dma_sconfig.dst_addr;
@@ -758,7 +776,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
/* Set device burst size */
src_best_burst = stm32_dma_get_best_burst(buf_len,
src_maxburst,
- threshold,
+ fifoth,
src_addr_width);
chan->mem_burst = src_best_burst;
src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
@@ -766,7 +784,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
return src_burst_size;
/* Set memory data size */
- dst_addr_width = stm32_dma_get_max_width(buf_len, threshold);
+ dst_addr_width = stm32_dma_get_max_width(buf_len, fifoth);
chan->mem_width = dst_addr_width;
dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
if (dst_bus_width < 0)
@@ -776,7 +794,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
dst_maxburst = STM32_DMA_MAX_BURST;
dst_best_burst = stm32_dma_get_best_burst(buf_len,
dst_maxburst,
- threshold,
+ fifoth,
dst_addr_width);
chan->mem_burst = dst_best_burst;
dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
@@ -791,7 +809,8 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
/* Set FIFO threshold */
chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
- chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(threshold);
+ if (fifoth != STM32_DMA_FIFO_THRESHOLD_NONE)
+ chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(fifoth);
/* Set peripheral address */
chan->chan_reg.dma_spar = chan->dma_sconfig.src_addr;
@@ -1216,6 +1235,8 @@ static void stm32_dma_set_config(struct stm32_dma_chan *chan,
chan->chan_reg.dma_scr |= STM32_DMA_SCR_TEIE | STM32_DMA_SCR_TCIE;
chan->threshold = STM32_DMA_THRESHOLD_FTR_GET(cfg->features);
+ if (STM32_DMA_DIRECT_MODE_GET(cfg->features))
+ chan->threshold = STM32_DMA_FIFO_THRESHOLD_NONE;
}
static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
--
2.17.1