[PATCH 0/6] Add few updates to the STM32 SPI driver

[PATCH 0/6] Add few updates to the STM32 SPI driver

[Clément Le Goffic]

This series aims to improve the STM32 SPI driver in different areas.
It adds SPI_READY mode, fixes an issue raised by a kernel bot,
add the ability to use DMA-MDMA chaining for RX and deprecate an ST bindings
vendor property.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
Clément Le Goffic (6):
      spi: stm32: Add SPI_READY mode to spi controller
      spi: stm32: Check for cfg availability in stm32_spi_probe
      dt-bindings: spi: stm32: update bindings with SPI Rx DMA-MDMA chaining
      spi: stm32: use STM32 DMA with STM32 MDMA to enhance DDR use
      spi: stm32: deprecate `st,spi-midi-ns` property
      dt-bindings: spi: stm32: deprecate `st,spi-midi-ns` property

 .../bindings/spi/spi-peripheral-props.yaml         |   1 +
 .../devicetree/bindings/spi/st,stm32-spi.yaml      |  48 +++-
 drivers/spi/spi-stm32.c                            | 310 ++++++++++++++++++---
 3 files changed, 325 insertions(+), 34 deletions(-)
---
base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e
change-id: 20250527-spi-upstream-1ba488d814e7

Best regards,
-- 
Clément Le Goffic <clement.legoffic@foss.st.com>

[PATCH 1/6] spi: stm32: Add SPI_READY mode to spi controller

[Clément Le Goffic]

The spi ready functionality is supported by our peripheral in host and
target modes on STM32MP2x SoCs.
Update our spi controller driver to allow devices to use this
functionality.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/spi/spi-stm32.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index da3517d7102d..2bcd4a43676d 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -154,6 +154,9 @@
 /* STM32H7_SPI_I2SCFGR bit fields */
 #define STM32H7_SPI_I2SCFGR_I2SMOD	BIT(0)
 
+/* STM32MP25_SPICFG2 bit fields */
+#define STM32MP25_SPI_CFG2_RDIOM	BIT(13)
+
 /* STM32MP25 SPI registers bit fields */
 #define STM32MP25_SPI_HWCFGR1			0x3F0
 
@@ -222,6 +225,7 @@ struct stm32_spi_reg {
  * @rx: SPI RX data register
  * @tx: SPI TX data register
  * @fullcfg: SPI full or limited feature set register
+ * @rdy_en: SPI ready feature register
  */
 struct stm32_spi_regspec {
 	const struct stm32_spi_reg en;
@@ -235,6 +239,7 @@ struct stm32_spi_regspec {
 	const struct stm32_spi_reg rx;
 	const struct stm32_spi_reg tx;
 	const struct stm32_spi_reg fullcfg;
+	const struct stm32_spi_reg rdy_en;
 };
 
 struct stm32_spi;
@@ -415,6 +420,8 @@ static const struct stm32_spi_regspec stm32mp25_spi_regspec = {
 	.tx = { STM32H7_SPI_TXDR },
 
 	.fullcfg = { STM32MP25_SPI_HWCFGR1, STM32MP25_SPI_HWCFGR1_FULLCFG },
+
+	.rdy_en = { STM32H7_SPI_CFG2, STM32MP25_SPI_CFG2_RDIOM },
 };
 
 static inline void stm32_spi_set_bits(struct stm32_spi *spi,
@@ -1172,15 +1179,21 @@ static int stm32_spi_prepare_msg(struct spi_controller *ctrl,
 	else
 		clrb |= spi->cfg->regs->cs_high.mask;
 
-	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d\n",
+	if (spi_dev->mode & SPI_READY)
+		setb |= spi->cfg->regs->rdy_en.mask;
+	else
+		clrb |= spi->cfg->regs->rdy_en.mask;
+
+	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d rdy=%d\n",
 		!!(spi_dev->mode & SPI_CPOL),
 		!!(spi_dev->mode & SPI_CPHA),
 		!!(spi_dev->mode & SPI_LSB_FIRST),
-		!!(spi_dev->mode & SPI_CS_HIGH));
+		!!(spi_dev->mode & SPI_CS_HIGH),
+		!!(spi_dev->mode & SPI_READY));
 
 	spin_lock_irqsave(&spi->lock, flags);
 
-	/* CPOL, CPHA and LSB FIRST bits have common register */
+	/* CPOL, CPHA, LSB FIRST, CS_HIGH and RDY_EN bits have common register */
 	if (clrb || setb)
 		writel_relaxed(
 			(readl_relaxed(spi->base + spi->cfg->regs->cpol.reg) &
@@ -1768,6 +1781,13 @@ static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
 	spi->cur_bpw = transfer->bits_per_word;
 	spi->cfg->set_bpw(spi);
 
+	if (spi_dev->mode & SPI_READY && spi->cur_bpw < 8) {
+		writel_relaxed(readl_relaxed(spi->base + spi->cfg->regs->rdy_en.reg) &
+				~spi->cfg->regs->rdy_en.mask,
+					spi->base + spi->cfg->regs->rdy_en.reg);
+		dev_dbg(spi->dev, "RDY logic disabled as bits per word < 8\n");
+	}
+
 	/* Update spi->cur_speed with real clock speed */
 	if (STM32_SPI_HOST_MODE(spi)) {
 		mbr = stm32_spi_prepare_mbr(spi, transfer->speed_hz,
@@ -2179,7 +2199,7 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	ctrl->auto_runtime_pm = true;
 	ctrl->bus_num = pdev->id;
 	ctrl->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST |
-			  SPI_3WIRE;
+			  SPI_3WIRE | SPI_READY;
 	ctrl->bits_per_word_mask = spi->cfg->get_bpw_mask(spi);
 	ctrl->max_speed_hz = spi->clk_rate / spi->cfg->baud_rate_div_min;
 	ctrl->min_speed_hz = spi->clk_rate / spi->cfg->baud_rate_div_max;

-- 
2.43.0

[PATCH 2/6] spi: stm32: Check for cfg availability in stm32_spi_probe

[Clément Le Goffic]

The stm32_spi_probe function now includes a check to ensure that the
pointer returned by of_device_get_match_data is not NULL before
accessing its members. This resolves a warning where a potential NULL
pointer dereference could occur when accessing cfg->has_device_mode.

Before accessing the 'has_device_mode' member, we verify that 'cfg' is
not NULL. If 'cfg' is NULL, an error message is logged.

This change ensures that the driver does not attempt to access
configuration data if it is not available, thus preventing a potential
system crash due to a NULL pointer dereference.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310191831.MLwx1c6x-lkp@intel.com/
Fixes: fee681646fc8 ("spi: stm32: disable device mode with st,stm32f4-spi compatible")
---
 drivers/spi/spi-stm32.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 2bcd4a43676d..8b61caf770a2 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -2089,9 +2089,15 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	struct resource *res;
 	struct reset_control *rst;
 	struct device_node *np = pdev->dev.of_node;
+	const struct stm32_spi_cfg *cfg;
 	bool device_mode;
 	int ret;
-	const struct stm32_spi_cfg *cfg = of_device_get_match_data(&pdev->dev);
+
+	cfg = of_device_get_match_data(&pdev->dev);
+	if (!cfg) {
+		dev_err(&pdev->dev, "Failed to get match data for platform\n");
+		return -ENODEV;
+	}
 
 	device_mode = of_property_read_bool(np, "spi-slave");
 	if (!cfg->has_device_mode && device_mode) {

-- 
2.43.0

[PATCH 3/6] dt-bindings: spi: stm32: update bindings with SPI Rx DMA-MDMA chaining

[Clément Le Goffic]

Add MDMA channel, and new sram property which are mandatory to enable
SPI Rx DMA-MDMA chaining.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 .../devicetree/bindings/spi/st,stm32-spi.yaml      | 48 +++++++++++++++++++++-
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
index 76e43c0ce36c..ca880a226afa 100644
--- a/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
+++ b/Documentation/devicetree/bindings/spi/st,stm32-spi.yaml
@@ -18,6 +18,38 @@ maintainers:
 
 allOf:
   - $ref: spi-controller.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: st,stm32f4-spi
+
+    then:
+      properties:
+        st,spi-midi-ns: false
+        sram: false
+        dmas:
+          maxItems: 2
+        dma-names:
+          items:
+            - const: rx
+            - const: tx
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: st,stm32mp25-spi
+
+    then:
+      properties:
+        sram: false
+        dmas:
+          maxItems: 2
+        dma-names:
+          items:
+            - const: rx
+            - const: tx
 
 properties:
   compatible:
@@ -41,16 +73,28 @@ properties:
 
   dmas:
     description: |
-      DMA specifiers for tx and rx dma. DMA fifo mode must be used. See
-      the STM32 DMA controllers bindings Documentation/devicetree/bindings/dma/stm32/*.yaml.
+      DMA specifiers for tx and rx channels. DMA fifo mode must be used. See
+      the STM32 DMA bindings Documentation/devicetree/bindings/dma/stm32/st,*dma.yaml
+    minItems: 2
     items:
       - description: rx DMA channel
       - description: tx DMA channel
+      - description: rxm2m MDMA channel
 
   dma-names:
+    minItems: 2
     items:
       - const: rx
       - const: tx
+      - const: rxm2m
+
+  sram:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: |
+      Phandles to a reserved SRAM region which is used as temporary
+      storage memory between DMA and MDMA engines.
+      The region should be defined as child node of the AHB SRAM node
+      as per the generic bindings in Documentation/devicetree/bindings/sram/sram.yaml
 
   access-controllers:
     minItems: 1

-- 
2.43.0

[PATCH 4/6] spi: stm32: use STM32 DMA with STM32 MDMA to enhance DDR use

[Clément Le Goffic]

The STM32 DMA doesn't have the ability to generate convenient burst
transfer on the DDR, ensuring the best load of the AXI & DDR.
To avoid this bad load of the AXI & DDR, STM32 MDMA can be used to transfer
data to the DDR, being triggered by STM32 DMA channel transfer
completion.
An SRAM buffer is used between DMA and MDMA. So the MDMA always does
MEM_TO_MEM transfers (from/to SRAM to/from DDR), and the DMA uses SRAM
instead of DDR with DEV_TO_MEM transfers.
SPI RX DMA (DEV_TO_MEM) becomes:
SPI RX FIFO ==DMA==> SRAM ==MDMA==> DDR

In RX (DEV_TO_MEM), EOT interrupt is used to pause the DMA channel (which
will raise a transfer complete) to trigger the MDMA to flush the SRAM (when
transfer length is not aligned on SRAM period).
TX remains on the former implementation.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/spi/spi-stm32.c | 251 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 228 insertions(+), 23 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 8b61caf770a2..8581f24c111f 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -9,7 +9,9 @@
 #include <linux/debugfs.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
+#include <linux/genalloc.h>
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
@@ -328,6 +330,11 @@ struct stm32_spi_cfg {
  * @dma_rx: dma channel for RX transfer
  * @phys_addr: SPI registers physical base address
  * @device_mode: the controller is configured as SPI device
+ * @sram_pool: SRAM pool for DMA transfers
+ * @sram_rx_buf_size: size of SRAM buffer for RX transfer
+ * @sram_rx_buf: SRAM buffer for RX transfer
+ * @sram_dma_rx_buf: SRAM buffer physical address for RX transfer
+ * @mdma_rx: MDMA channel for RX transfer
  */
 struct stm32_spi {
 	struct device *dev;
@@ -362,6 +369,12 @@ struct stm32_spi {
 	dma_addr_t phys_addr;
 
 	bool device_mode;
+
+	struct gen_pool *sram_pool;
+	size_t sram_rx_buf_size;
+	void *sram_rx_buf;
+	dma_addr_t sram_dma_rx_buf;
+	struct dma_chan *mdma_rx;
 };
 
 static const struct stm32_spi_regspec stm32fx_spi_regspec = {
@@ -885,8 +898,11 @@ static void stm32h7_spi_disable(struct stm32_spi *spi)
 
 	if (spi->cur_usedma && spi->dma_tx)
 		dmaengine_terminate_async(spi->dma_tx);
-	if (spi->cur_usedma && spi->dma_rx)
+	if (spi->cur_usedma && spi->dma_rx) {
 		dmaengine_terminate_async(spi->dma_rx);
+		if (spi->mdma_rx)
+			dmaengine_terminate_async(spi->mdma_rx);
+	}
 
 	stm32_spi_clr_bits(spi, STM32H7_SPI_CR1, STM32H7_SPI_CR1_SPE);
 
@@ -1098,10 +1114,13 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 	}
 
 	if (sr & STM32H7_SPI_SR_EOT) {
+		dev_dbg(spi->dev, "End of transfer\n");
 		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
 			stm32h7_spi_read_rxfifo(spi);
 		if (!spi->cur_usedma ||
-		    (spi->cur_comm == SPI_SIMPLEX_TX || spi->cur_comm == SPI_3WIRE_TX))
+		    (spi->cur_comm == SPI_SIMPLEX_TX || spi->cur_comm == SPI_3WIRE_TX) ||
+		    (spi->mdma_rx && (spi->cur_comm == SPI_SIMPLEX_RX ||
+		     spi->cur_comm == SPI_FULL_DUPLEX)))
 			end = true;
 	}
 
@@ -1118,6 +1137,11 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 	spin_unlock_irqrestore(&spi->lock, flags);
 
 	if (end) {
+		if (spi->cur_usedma && spi->mdma_rx) {
+			dmaengine_pause(spi->dma_rx);
+			/* Wait for callback */
+			return IRQ_HANDLED;
+		}
 		stm32h7_spi_disable(spi);
 		spi_finalize_current_transfer(ctrl);
 	}
@@ -1423,6 +1447,8 @@ static void stm32h7_spi_transfer_one_dma_start(struct stm32_spi *spi)
 	/* Enable the interrupts */
 	if (spi->cur_comm == SPI_SIMPLEX_TX || spi->cur_comm == SPI_3WIRE_TX)
 		ier |= STM32H7_SPI_IER_EOTIE | STM32H7_SPI_IER_TXTFIE;
+	if (spi->mdma_rx && (spi->cur_comm == SPI_SIMPLEX_RX || spi->cur_comm == SPI_FULL_DUPLEX))
+		ier |= STM32H7_SPI_IER_EOTIE;
 
 	stm32_spi_set_bits(spi, STM32H7_SPI_IER, ier);
 
@@ -1432,6 +1458,119 @@ static void stm32h7_spi_transfer_one_dma_start(struct stm32_spi *spi)
 		stm32_spi_set_bits(spi, STM32H7_SPI_CR1, STM32H7_SPI_CR1_CSTART);
 }
 
+/**
+ * stm32_spi_prepare_rx_dma_mdma_chaining - Prepare RX DMA and MDMA chaining
+ * @spi: pointer to the spi controller data structure
+ * @xfer: pointer to the spi transfer
+ * @rx_dma_conf: pointer to the DMA configuration for RX channel
+ * @rx_dma_desc: pointer to the RX DMA descriptor
+ * @rx_mdma_desc: pointer to the RX MDMA descriptor
+ *
+ * It must return 0 if the chaining is possible or an error code if not.
+ */
+static int stm32_spi_prepare_rx_dma_mdma_chaining(struct stm32_spi *spi,
+						  struct spi_transfer *xfer,
+						  struct dma_slave_config *rx_dma_conf,
+						  struct dma_async_tx_descriptor **rx_dma_desc,
+						  struct dma_async_tx_descriptor **rx_mdma_desc)
+{
+	struct dma_slave_config rx_mdma_conf = {0};
+	u32 sram_period, nents = 0, spi_s_len;
+	struct sg_table dma_sgt, mdma_sgt;
+	struct scatterlist *spi_s, *s;
+	dma_addr_t dma_buf;
+	int i, ret;
+
+	sram_period = spi->sram_rx_buf_size / 2;
+
+	/* Configure MDMA RX channel */
+	rx_mdma_conf.direction = rx_dma_conf->direction;
+	rx_mdma_conf.src_addr = spi->sram_dma_rx_buf;
+	rx_mdma_conf.peripheral_config = rx_dma_conf->peripheral_config;
+	rx_mdma_conf.peripheral_size = rx_dma_conf->peripheral_size;
+	dmaengine_slave_config(spi->mdma_rx, &rx_mdma_conf);
+
+	/* Count the number of entries needed */
+	for_each_sg(xfer->rx_sg.sgl, spi_s, xfer->rx_sg.nents, i)
+		if (sg_dma_len(spi_s) > sram_period)
+			nents += DIV_ROUND_UP(sg_dma_len(spi_s), sram_period);
+		else
+			nents++;
+
+	/* Prepare DMA slave_sg DBM transfer DEV_TO_MEM (RX>MEM=SRAM) */
+	ret = sg_alloc_table(&dma_sgt, nents, GFP_ATOMIC);
+	if (ret)
+		return ret;
+
+	spi_s = xfer->rx_sg.sgl;
+	spi_s_len = sg_dma_len(spi_s);
+	dma_buf = spi->sram_dma_rx_buf;
+	for_each_sg(dma_sgt.sgl, s, dma_sgt.nents, i) {
+		size_t bytes = min_t(size_t, spi_s_len, sram_period);
+
+		sg_dma_len(s) = bytes;
+		sg_dma_address(s) = dma_buf;
+		spi_s_len -= bytes;
+
+		if (!spi_s_len && sg_next(spi_s)) {
+			spi_s = sg_next(spi_s);
+			spi_s_len = sg_dma_len(spi_s);
+			dma_buf = spi->sram_dma_rx_buf;
+		} else { /* DMA configured in DBM: it will swap between the SRAM periods */
+			if (i & 1)
+				dma_buf += sram_period;
+			else
+				dma_buf = spi->sram_dma_rx_buf;
+		}
+	}
+
+	*rx_dma_desc = dmaengine_prep_slave_sg(spi->dma_rx, dma_sgt.sgl,
+					       dma_sgt.nents, rx_dma_conf->direction,
+					       DMA_PREP_INTERRUPT);
+	sg_free_table(&dma_sgt);
+
+	if (!rx_dma_desc)
+		return -EINVAL;
+
+	/* Prepare MDMA slave_sg transfer MEM_TO_MEM (SRAM>DDR) */
+	ret = sg_alloc_table(&mdma_sgt, nents, GFP_ATOMIC);
+	if (ret) {
+		rx_dma_desc = NULL;
+		return ret;
+	}
+
+	spi_s = xfer->rx_sg.sgl;
+	spi_s_len = sg_dma_len(spi_s);
+	dma_buf = sg_dma_address(spi_s);
+	for_each_sg(mdma_sgt.sgl, s, mdma_sgt.nents, i) {
+		size_t bytes = min_t(size_t, spi_s_len, sram_period);
+
+		sg_dma_len(s) = bytes;
+		sg_dma_address(s) = dma_buf;
+		spi_s_len -= bytes;
+
+		if (!spi_s_len && sg_next(spi_s)) {
+			spi_s = sg_next(spi_s);
+			spi_s_len = sg_dma_len(spi_s);
+			dma_buf = sg_dma_address(spi_s);
+		} else {
+			dma_buf += bytes;
+		}
+	}
+
+	*rx_mdma_desc = dmaengine_prep_slave_sg(spi->mdma_rx, mdma_sgt.sgl,
+						mdma_sgt.nents, rx_mdma_conf.direction,
+						DMA_PREP_INTERRUPT);
+	sg_free_table(&mdma_sgt);
+
+	if (!rx_mdma_desc) {
+		rx_dma_desc = NULL;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * stm32_spi_transfer_one_dma - transfer a single spi_transfer using DMA
  * @spi: pointer to the spi controller data structure
@@ -1443,38 +1582,43 @@ static void stm32h7_spi_transfer_one_dma_start(struct stm32_spi *spi)
 static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
 				      struct spi_transfer *xfer)
 {
+	struct dma_async_tx_descriptor *rx_mdma_desc = NULL, *rx_dma_desc = NULL;
+	struct dma_async_tx_descriptor *tx_dma_desc = NULL;
 	struct dma_slave_config tx_dma_conf, rx_dma_conf;
-	struct dma_async_tx_descriptor *tx_dma_desc, *rx_dma_desc;
 	unsigned long flags;
+	int ret = 0;
 
 	spin_lock_irqsave(&spi->lock, flags);
 
-	rx_dma_desc = NULL;
 	if (spi->rx_buf && spi->dma_rx) {
 		stm32_spi_dma_config(spi, spi->dma_rx, &rx_dma_conf, DMA_DEV_TO_MEM);
-		dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
+		if (spi->mdma_rx) {
+			rx_dma_conf.peripheral_size = 1;
+			dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
 
-		/* Enable Rx DMA request */
-		stm32_spi_set_bits(spi, spi->cfg->regs->dma_rx_en.reg,
-				   spi->cfg->regs->dma_rx_en.mask);
-
-		rx_dma_desc = dmaengine_prep_slave_sg(
-					spi->dma_rx, xfer->rx_sg.sgl,
-					xfer->rx_sg.nents,
-					rx_dma_conf.direction,
-					DMA_PREP_INTERRUPT);
+			ret = stm32_spi_prepare_rx_dma_mdma_chaining(spi, xfer, &rx_dma_conf,
+								     &rx_dma_desc, &rx_mdma_desc);
+			if (ret) { /* RX DMA MDMA chaining not possible, fallback to DMA only */
+				rx_dma_conf.peripheral_config = 0;
+				rx_dma_desc = NULL;
+			}
+		}
+		if (!rx_dma_desc) {
+			dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
+			rx_dma_desc = dmaengine_prep_slave_sg(spi->dma_rx, xfer->rx_sg.sgl,
+							      xfer->rx_sg.nents,
+							      rx_dma_conf.direction,
+							      DMA_PREP_INTERRUPT);
+		}
 	}
 
-	tx_dma_desc = NULL;
 	if (spi->tx_buf && spi->dma_tx) {
 		stm32_spi_dma_config(spi, spi->dma_tx, &tx_dma_conf, DMA_MEM_TO_DEV);
 		dmaengine_slave_config(spi->dma_tx, &tx_dma_conf);
-
-		tx_dma_desc = dmaengine_prep_slave_sg(
-					spi->dma_tx, xfer->tx_sg.sgl,
-					xfer->tx_sg.nents,
-					tx_dma_conf.direction,
-					DMA_PREP_INTERRUPT);
+		tx_dma_desc = dmaengine_prep_slave_sg(spi->dma_tx, xfer->tx_sg.sgl,
+						      xfer->tx_sg.nents,
+						      tx_dma_conf.direction,
+						      DMA_PREP_INTERRUPT);
 	}
 
 	if ((spi->tx_buf && spi->dma_tx && !tx_dma_desc) ||
@@ -1485,9 +1629,25 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
 		goto dma_desc_error;
 
 	if (rx_dma_desc) {
-		rx_dma_desc->callback = spi->cfg->dma_rx_cb;
-		rx_dma_desc->callback_param = spi;
+		if (rx_mdma_desc) {
+			rx_mdma_desc->callback = spi->cfg->dma_rx_cb;
+			rx_mdma_desc->callback_param = spi;
+		} else {
+			rx_dma_desc->callback = spi->cfg->dma_rx_cb;
+			rx_dma_desc->callback_param = spi;
+		}
 
+		/* Enable Rx DMA request */
+		stm32_spi_set_bits(spi, spi->cfg->regs->dma_rx_en.reg,
+				   spi->cfg->regs->dma_rx_en.mask);
+		if (rx_mdma_desc) {
+			if (dma_submit_error(dmaengine_submit(rx_mdma_desc))) {
+				dev_err(spi->dev, "Rx MDMA submit failed\n");
+				goto dma_desc_error;
+			}
+			/* Enable Rx MDMA channel */
+			dma_async_issue_pending(spi->mdma_rx);
+		}
 		if (dma_submit_error(dmaengine_submit(rx_dma_desc))) {
 			dev_err(spi->dev, "Rx DMA submit failed\n");
 			goto dma_desc_error;
@@ -1522,6 +1682,8 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
 	return 1;
 
 dma_submit_error:
+	if (spi->mdma_rx)
+		dmaengine_terminate_sync(spi->mdma_rx);
 	if (spi->dma_rx)
 		dmaengine_terminate_sync(spi->dma_rx);
 
@@ -1533,6 +1695,9 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
 
 	dev_info(spi->dev, "DMA issue: fall back to irq transfer\n");
 
+	if (spi->sram_rx_buf)
+		memset(spi->sram_rx_buf, 0, spi->sram_rx_buf_size);
+
 	spi->cur_usedma = false;
 	return spi->cfg->transfer_one_irq(spi);
 }
@@ -1891,6 +2056,9 @@ static int stm32_spi_unprepare_msg(struct spi_controller *ctrl,
 
 	spi->cfg->disable(spi);
 
+	if (spi->sram_rx_buf)
+		memset(spi->sram_rx_buf, 0, spi->sram_rx_buf_size);
+
 	return 0;
 }
 
@@ -2245,6 +2413,33 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	if (spi->dma_tx || spi->dma_rx)
 		ctrl->can_dma = stm32_spi_can_dma;
 
+	spi->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
+	if (spi->sram_pool) {
+		spi->sram_rx_buf_size = gen_pool_size(spi->sram_pool);
+		dev_info(&pdev->dev, "SRAM pool: %zu KiB for RX DMA/MDMA chaining\n",
+			 spi->sram_rx_buf_size / 1024);
+		spi->sram_rx_buf = gen_pool_dma_zalloc(spi->sram_pool, spi->sram_rx_buf_size,
+						       &spi->sram_dma_rx_buf);
+		if (!spi->sram_rx_buf) {
+			dev_err(&pdev->dev, "failed to allocate SRAM buffer\n");
+		} else {
+			spi->mdma_rx = dma_request_chan(spi->dev, "rxm2m");
+			if (IS_ERR(spi->mdma_rx)) {
+				ret = PTR_ERR(spi->mdma_rx);
+				spi->mdma_rx = NULL;
+				if (ret == -EPROBE_DEFER) {
+					goto err_pool_free;
+				} else {
+					gen_pool_free(spi->sram_pool,
+						      (unsigned long)spi->sram_rx_buf,
+						      spi->sram_rx_buf_size);
+					dev_warn(&pdev->dev,
+						 "failed to request rx mdma channel, DMA only\n");
+				}
+			}
+		}
+	}
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev,
 					 STM32_SPI_AUTOSUSPEND_DELAY);
 	pm_runtime_use_autosuspend(&pdev->dev);
@@ -2272,6 +2467,11 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_set_suspended(&pdev->dev);
 	pm_runtime_dont_use_autosuspend(&pdev->dev);
+
+	if (spi->mdma_rx)
+		dma_release_channel(spi->mdma_rx);
+err_pool_free:
+	gen_pool_free(spi->sram_pool, (unsigned long)spi->sram_rx_buf, spi->sram_rx_buf_size);
 err_dma_release:
 	if (spi->dma_tx)
 		dma_release_channel(spi->dma_tx);
@@ -2302,6 +2502,11 @@ static void stm32_spi_remove(struct platform_device *pdev)
 		dma_release_channel(ctrl->dma_tx);
 	if (ctrl->dma_rx)
 		dma_release_channel(ctrl->dma_rx);
+	if (spi->mdma_rx)
+		dma_release_channel(spi->mdma_rx);
+	if (spi->sram_rx_buf)
+		gen_pool_free(spi->sram_pool, (unsigned long)spi->sram_rx_buf,
+			      spi->sram_rx_buf_size);
 
 	clk_disable_unprepare(spi->clk);
 

-- 
2.43.0

[PATCH 5/6] spi: stm32: deprecate `st,spi-midi-ns` property

[Clément Le Goffic]

The `st,spi-midi-ns` property, which was used to set a nanosecond delay
between transferred words, is now deprecated.
This functionality is now supported by the SPI framework through the
`spi_transfer` struct's `word_delay` variable.
Therefore, the private `st,spi-midi-ns` property is no longer needed and
has been deprecated in favor of the generic solution.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/spi/spi-stm32.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 8581f24c111f..3d20f09f1ae7 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -283,7 +283,7 @@ struct stm32_spi_cfg {
 	int (*config)(struct stm32_spi *spi);
 	void (*set_bpw)(struct stm32_spi *spi);
 	int (*set_mode)(struct stm32_spi *spi, unsigned int comm_type);
-	void (*set_data_idleness)(struct stm32_spi *spi, u32 length);
+	void (*set_data_idleness)(struct stm32_spi *spi, struct spi_transfer *xfer);
 	int (*set_number_of_data)(struct stm32_spi *spi, u32 length);
 	void (*write_tx)(struct stm32_spi *spi);
 	void (*read_rx)(struct stm32_spi *spi);
@@ -1880,11 +1880,26 @@ static int stm32h7_spi_set_mode(struct stm32_spi *spi, unsigned int comm_type)
  * stm32h7_spi_data_idleness - configure minimum time delay inserted between two
  *			       consecutive data frames in host mode
  * @spi: pointer to the spi controller data structure
- * @len: transfer len
+ * @xfer: pointer to spi transfer
  */
-static void stm32h7_spi_data_idleness(struct stm32_spi *spi, u32 len)
+static void stm32h7_spi_data_idleness(struct stm32_spi *spi, struct spi_transfer *xfer)
 {
 	u32 cfg2_clrb = 0, cfg2_setb = 0;
+	u32 len = xfer->len;
+	u32 spi_delay_ns;
+
+	spi_delay_ns = spi_delay_to_ns(&xfer->word_delay, xfer);
+
+	if (spi->cur_midi != 0) {
+		dev_warn(spi->dev, "st,spi-midi-ns DT property is deprecated\n");
+		if (spi_delay_ns) {
+			dev_warn(spi->dev, "Overriding st,spi-midi-ns with word_delay_ns %d\n",
+				 spi_delay_ns);
+				spi->cur_midi = spi_delay_ns;
+			}
+	} else {
+		spi->cur_midi = spi_delay_ns;
+	}
 
 	cfg2_clrb |= STM32H7_SPI_CFG2_MIDI;
 	if ((len > 1) && (spi->cur_midi > 0)) {
@@ -1975,7 +1990,7 @@ static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
 	spi->cur_comm = comm_type;
 
 	if (STM32_SPI_HOST_MODE(spi) && spi->cfg->set_data_idleness)
-		spi->cfg->set_data_idleness(spi, transfer->len);
+		spi->cfg->set_data_idleness(spi, transfer);
 
 	if (spi->cur_bpw <= 8)
 		nb_words = transfer->len;

-- 
2.43.0

[PATCH 6/6] dt-bindings: spi: stm32: deprecate `st,spi-midi-ns` property

[Clément Le Goffic]

The vendor `st,spi-midi-ns` property is no longer needed and
has been deprecated in favor of a generic solution.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 8fc17e16efb2..8b6e8fc009db 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -115,6 +115,7 @@ properties:
     maxItems: 4
 
   st,spi-midi-ns:
+    deprecated: true
     description: |
       Only for STM32H7, (Master Inter-Data Idleness) minimum time
       delay in nanoseconds inserted between two consecutive data frames.

-- 
2.43.0

Re: [PATCH 0/6] Add few updates to the STM32 SPI driver

[Mark Brown]

On Mon, 16 Jun 2025 11:21:01 +0200, Clément Le Goffic wrote:
> This series aims to improve the STM32 SPI driver in different areas.
> It adds SPI_READY mode, fixes an issue raised by a kernel bot,
> add the ability to use DMA-MDMA chaining for RX and deprecate an ST bindings
> vendor property.
> 
> 

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/6] spi: stm32: Add SPI_READY mode to spi controller
      commit: e4feefa5c71912ebfcb97a3dbe2b021fd1cea9d1
[2/6] spi: stm32: Check for cfg availability in stm32_spi_probe
      commit: 21f1c800f6620e43f31dfd76709dbac8ebaa5a16
[3/6] dt-bindings: spi: stm32: update bindings with SPI Rx DMA-MDMA chaining
      commit: bd60f94a3eb4f80cb66c9687d640554fd0c579d0
[4/6] spi: stm32: use STM32 DMA with STM32 MDMA to enhance DDR use
      commit: d17dd2f1d8a1d919e39c6302b024f135a2f90773
[5/6] spi: stm32: deprecate `st,spi-midi-ns` property
      commit: 4956bf44524394211ca80aa04d0c9e1e9bb0219d
[6/6] dt-bindings: spi: stm32: deprecate `st,spi-midi-ns` property
      commit: 9a944494c299fabf3cc781798eb7c02a0bece364

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark