[PATCH v3] dt-bindings: spi: tegra: Document IOMMU property for Tegra234 QSPI

[PATCH v3] dt-bindings: spi: tegra: Document IOMMU property for Tegra234 QSPI

[Vishwaroop A]

Add the 'iommus' property to the Tegra QSPI device tree binding.
The property is needed for Tegra234 when using the internal DMA
controller, and is not supported on other Tegra chips, as DMA is
handled by an external controller.

Signed-off-by: Vishwaroop A <va@nvidia.com>
---
 .../bindings/spi/nvidia,tegra210-quad.yaml    | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
index 48e97e240265..04d3b1a47392 100644
--- a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
+++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
@@ -10,9 +10,6 @@ maintainers:
   - Thierry Reding <thierry.reding@gmail.com>
   - Jonathan Hunter <jonathanh@nvidia.com>
 
-allOf:
-  - $ref: spi-controller.yaml#
-
 properties:
   compatible:
     enum:
@@ -47,6 +44,9 @@ properties:
       - const: rx
       - const: tx
 
+  iommus:
+    maxItems: 1
+
 patternProperties:
   "@[0-9a-f]+$":
     type: object
@@ -69,6 +69,19 @@ required:
 
 unevaluatedProperties: false
 
+allOf:
+  - $ref: spi-controller.yaml#
+  - if:
+      properties:
+        compatible:
+          const: nvidia,tegra234-qspi
+    then:
+      properties:
+        iommus: true
+    else:
+      properties:
+        iommus: false
+
 examples:
   - |
     #include <dt-bindings/clock/tegra210-car.h>
-- 
2.17.1

[PATCH v2] spi: tegra210-quad: Add support for internal DMA

[Vishwaroop A]

Previous generations of Tegra supported DMA operations by an external
DMA controller, but the QSPI on Tegra234 devices now have an internal
DMA controller.

Introduce routines to initialize and configure internal DMA channels
for both transmit and receive paths. Set up DMA mapping functions to
manage buffer addresses effectively.

The variable err is changed to num_errors to more accurately represent
its purpose in the code. The updated name clarifies that the variable
tracks the number of errors encountered during execution, rather than
serving as a generic error flag or code.

Tegra241 device supports DMA via an external DMA controller (GPCDMA), so
enable this.

Signed-off-by: Vishwaroop A <va@nvidia.com>
---
 drivers/spi/spi-tegra210-quad.c | 223 +++++++++++++++++++-------------
 1 file changed, 130 insertions(+), 93 deletions(-)

diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
index a93e19911ef1..953a4a74afeb 100644
--- a/drivers/spi/spi-tegra210-quad.c
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -111,6 +111,9 @@
 #define QSPI_DMA_BLK				0x024
 #define QSPI_DMA_BLK_SET(x)			(((x) & 0xffff) << 0)
 
+#define QSPI_DMA_MEM_ADDRESS			0x028
+#define QSPI_DMA_HI_ADDRESS			0x02c
+
 #define QSPI_TX_FIFO				0x108
 #define QSPI_RX_FIFO				0x188
 
@@ -167,9 +170,9 @@ enum tegra_qspi_transfer_type {
 };
 
 struct tegra_qspi_soc_data {
-	bool has_dma;
 	bool cmb_xfer_capable;
 	bool supports_tpm;
+	bool has_ext_dma;
 	unsigned int cs_count;
 };
 
@@ -605,13 +608,16 @@ static void tegra_qspi_dma_unmap_xfer(struct tegra_qspi *tqspi, struct spi_trans
 
 	len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
 
-	dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
-	dma_unmap_single(tqspi->dev, t->rx_dma, len, DMA_FROM_DEVICE);
+	if (t->tx_buf)
+		dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
+	if (t->rx_buf)
+		dma_unmap_single(tqspi->dev, t->rx_dma, len, DMA_FROM_DEVICE);
 }
 
 static int tegra_qspi_start_dma_based_transfer(struct tegra_qspi *tqspi, struct spi_transfer *t)
 {
 	struct dma_slave_config dma_sconfig = { 0 };
+	dma_addr_t rx_dma_phys, tx_dma_phys;
 	unsigned int len;
 	u8 dma_burst;
 	int ret = 0;
@@ -634,60 +640,88 @@ static int tegra_qspi_start_dma_based_transfer(struct tegra_qspi *tqspi, struct
 		len = tqspi->curr_dma_words * 4;
 
 	/* set attention level based on length of transfer */
-	val = 0;
-	if (len & 0xf) {
-		val |= QSPI_TX_TRIG_1 | QSPI_RX_TRIG_1;
-		dma_burst = 1;
-	} else if (((len) >> 4) & 0x1) {
-		val |= QSPI_TX_TRIG_4 | QSPI_RX_TRIG_4;
-		dma_burst = 4;
-	} else {
-		val |= QSPI_TX_TRIG_8 | QSPI_RX_TRIG_8;
-		dma_burst = 8;
+	if (tqspi->soc_data->has_ext_dma) {
+		val = 0;
+		if (len & 0xf) {
+			val |= QSPI_TX_TRIG_1 | QSPI_RX_TRIG_1;
+			dma_burst = 1;
+		} else if (((len) >> 4) & 0x1) {
+			val |= QSPI_TX_TRIG_4 | QSPI_RX_TRIG_4;
+			dma_burst = 4;
+		} else {
+			val |= QSPI_TX_TRIG_8 | QSPI_RX_TRIG_8;
+			dma_burst = 8;
+		}
+
+		tegra_qspi_writel(tqspi, val, QSPI_DMA_CTL);
 	}
 
-	tegra_qspi_writel(tqspi, val, QSPI_DMA_CTL);
 	tqspi->dma_control_reg = val;
 
 	dma_sconfig.device_fc = true;
+
 	if (tqspi->cur_direction & DATA_DIR_TX) {
-		dma_sconfig.dst_addr = tqspi->phys + QSPI_TX_FIFO;
-		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-		dma_sconfig.dst_maxburst = dma_burst;
-		ret = dmaengine_slave_config(tqspi->tx_dma_chan, &dma_sconfig);
-		if (ret < 0) {
-			dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
-			return ret;
-		}
+		if (tqspi->tx_dma_chan) {
+			dma_sconfig.dst_addr = tqspi->phys + QSPI_TX_FIFO;
+			dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+			dma_sconfig.dst_maxburst = dma_burst;
+			ret = dmaengine_slave_config(tqspi->tx_dma_chan, &dma_sconfig);
+			if (ret < 0) {
+				dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
+				return ret;
+			}
 
-		tegra_qspi_copy_client_txbuf_to_qspi_txbuf(tqspi, t);
-		ret = tegra_qspi_start_tx_dma(tqspi, t, len);
-		if (ret < 0) {
-			dev_err(tqspi->dev, "failed to starting TX DMA: %d\n", ret);
-			return ret;
+			tegra_qspi_copy_client_txbuf_to_qspi_txbuf(tqspi, t);
+			ret = tegra_qspi_start_tx_dma(tqspi, t, len);
+			if (ret < 0) {
+				dev_err(tqspi->dev, "failed to starting TX DMA: %d\n", ret);
+				return ret;
+			}
+		} else {
+			if (tqspi->is_packed)
+				tx_dma_phys = t->tx_dma;
+			else
+				tx_dma_phys = tqspi->tx_dma_phys;
+			tegra_qspi_copy_client_txbuf_to_qspi_txbuf(tqspi, t);
+			tegra_qspi_writel(tqspi, lower_32_bits(tx_dma_phys),
+					  QSPI_DMA_MEM_ADDRESS);
+			tegra_qspi_writel(tqspi, (upper_32_bits(tx_dma_phys) & 0xff),
+					  QSPI_DMA_HI_ADDRESS);
 		}
 	}
 
 	if (tqspi->cur_direction & DATA_DIR_RX) {
-		dma_sconfig.src_addr = tqspi->phys + QSPI_RX_FIFO;
-		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-		dma_sconfig.src_maxburst = dma_burst;
-		ret = dmaengine_slave_config(tqspi->rx_dma_chan, &dma_sconfig);
-		if (ret < 0) {
-			dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
-			return ret;
-		}
+		if (tqspi->rx_dma_chan) {
+			dma_sconfig.src_addr = tqspi->phys + QSPI_RX_FIFO;
+			dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+			dma_sconfig.src_maxburst = dma_burst;
+			ret = dmaengine_slave_config(tqspi->rx_dma_chan, &dma_sconfig);
+			if (ret < 0) {
+				dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
+				return ret;
+			}
 
-		dma_sync_single_for_device(tqspi->dev, tqspi->rx_dma_phys,
-					   tqspi->dma_buf_size,
-					   DMA_FROM_DEVICE);
+			dma_sync_single_for_device(tqspi->dev, tqspi->rx_dma_phys,
+						   tqspi->dma_buf_size, DMA_FROM_DEVICE);
 
-		ret = tegra_qspi_start_rx_dma(tqspi, t, len);
-		if (ret < 0) {
-			dev_err(tqspi->dev, "failed to start RX DMA: %d\n", ret);
-			if (tqspi->cur_direction & DATA_DIR_TX)
-				dmaengine_terminate_all(tqspi->tx_dma_chan);
-			return ret;
+			ret = tegra_qspi_start_rx_dma(tqspi, t, len);
+			if (ret < 0) {
+				dev_err(tqspi->dev, "failed to start RX DMA: %d\n", ret);
+				if (tqspi->cur_direction & DATA_DIR_TX)
+					dmaengine_terminate_all(tqspi->tx_dma_chan);
+				return ret;
+			}
+
+		} else {
+			if (tqspi->is_packed)
+				rx_dma_phys = t->rx_dma;
+			else
+				rx_dma_phys = tqspi->rx_dma_phys;
+
+			tegra_qspi_writel(tqspi, lower_32_bits(rx_dma_phys),
+					  QSPI_DMA_MEM_ADDRESS);
+			tegra_qspi_writel(tqspi, (upper_32_bits(rx_dma_phys) & 0xff),
+					  QSPI_DMA_HI_ADDRESS);
 		}
 	}
 
@@ -726,9 +760,6 @@ static int tegra_qspi_start_cpu_based_transfer(struct tegra_qspi *qspi, struct s
 
 static void tegra_qspi_deinit_dma(struct tegra_qspi *tqspi)
 {
-	if (!tqspi->soc_data->has_dma)
-		return;
-
 	if (tqspi->tx_dma_buf) {
 		dma_free_coherent(tqspi->dev, tqspi->dma_buf_size,
 				  tqspi->tx_dma_buf, tqspi->tx_dma_phys);
@@ -759,16 +790,29 @@ static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
 	u32 *dma_buf;
 	int err;
 
-	if (!tqspi->soc_data->has_dma)
-		return 0;
+	if (tqspi->soc_data->has_ext_dma) {
+		dma_chan = dma_request_chan(tqspi->dev, "rx");
+		if (IS_ERR(dma_chan)) {
+			err = PTR_ERR(dma_chan);
+			goto err_out;
+		}
 
-	dma_chan = dma_request_chan(tqspi->dev, "rx");
-	if (IS_ERR(dma_chan)) {
-		err = PTR_ERR(dma_chan);
-		goto err_out;
-	}
+		tqspi->rx_dma_chan = dma_chan;
 
-	tqspi->rx_dma_chan = dma_chan;
+		dma_chan = dma_request_chan(tqspi->dev, "tx");
+		if (IS_ERR(dma_chan)) {
+			err = PTR_ERR(dma_chan);
+			goto err_out;
+		}
+
+		tqspi->tx_dma_chan = dma_chan;
+	} else {
+		if (!device_iommu_mapped(tqspi->dev)) {
+			dev_warn(tqspi->dev,
+				 "IOMMU not enabled in device-tree, falling back to PIO mode\n");
+			return 0;
+		}
+	}
 
 	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
 	if (!dma_buf) {
@@ -779,14 +823,6 @@ static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
 	tqspi->rx_dma_buf = dma_buf;
 	tqspi->rx_dma_phys = dma_phys;
 
-	dma_chan = dma_request_chan(tqspi->dev, "tx");
-	if (IS_ERR(dma_chan)) {
-		err = PTR_ERR(dma_chan);
-		goto err_out;
-	}
-
-	tqspi->tx_dma_chan = dma_chan;
-
 	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
 	if (!dma_buf) {
 		err = -ENOMEM;
@@ -1128,15 +1164,12 @@ static int tegra_qspi_combined_seq_xfer(struct tegra_qspi *tqspi,
 			if (WARN_ON_ONCE(ret == 0)) {
 				dev_err_ratelimited(tqspi->dev,
 						    "QSPI Transfer failed with timeout\n");
-				if (tqspi->is_curr_dma_xfer &&
-				    (tqspi->cur_direction & DATA_DIR_TX))
-					dmaengine_terminate_all
-						(tqspi->tx_dma_chan);
-
-				if (tqspi->is_curr_dma_xfer &&
-				    (tqspi->cur_direction & DATA_DIR_RX))
-					dmaengine_terminate_all
-						(tqspi->rx_dma_chan);
+				if (tqspi->is_curr_dma_xfer) {
+					if ((tqspi->cur_direction & DATA_DIR_TX) && tqspi->tx_dma_chan)
+						dmaengine_terminate_all(tqspi->tx_dma_chan);
+					if ((tqspi->cur_direction & DATA_DIR_RX) && tqspi->rx_dma_chan)
+						dmaengine_terminate_all(tqspi->rx_dma_chan);
+				}
 
 				/* Abort transfer by resetting pio/dma bit */
 				if (!tqspi->is_curr_dma_xfer) {
@@ -1251,10 +1284,12 @@ static int tegra_qspi_non_combined_seq_xfer(struct tegra_qspi *tqspi,
 						  QSPI_DMA_TIMEOUT);
 		if (WARN_ON(ret == 0)) {
 			dev_err(tqspi->dev, "transfer timeout\n");
-			if (tqspi->is_curr_dma_xfer && (tqspi->cur_direction & DATA_DIR_TX))
-				dmaengine_terminate_all(tqspi->tx_dma_chan);
-			if (tqspi->is_curr_dma_xfer && (tqspi->cur_direction & DATA_DIR_RX))
-				dmaengine_terminate_all(tqspi->rx_dma_chan);
+			if (tqspi->is_curr_dma_xfer) {
+				if ((tqspi->cur_direction & DATA_DIR_TX) && tqspi->tx_dma_chan)
+					dmaengine_terminate_all(tqspi->tx_dma_chan);
+				if ((tqspi->cur_direction & DATA_DIR_RX) && tqspi->rx_dma_chan)
+					dmaengine_terminate_all(tqspi->rx_dma_chan);
+			}
 			tegra_qspi_handle_error(tqspi);
 			ret = -EIO;
 			goto complete_xfer;
@@ -1323,7 +1358,7 @@ static bool tegra_qspi_validate_cmb_seq(struct tegra_qspi *tqspi,
 			return false;
 		xfer = list_next_entry(xfer, transfer_list);
 	}
-	if (!tqspi->soc_data->has_dma && xfer->len > (QSPI_FIFO_DEPTH << 2))
+	if (!tqspi->soc_data->has_ext_dma && xfer->len > (QSPI_FIFO_DEPTH << 2))
 		return false;
 
 	return true;
@@ -1384,41 +1419,43 @@ static irqreturn_t handle_dma_based_xfer(struct tegra_qspi *tqspi)
 	unsigned int total_fifo_words;
 	unsigned long flags;
 	long wait_status;
-	int err = 0;
+	int num_errors = 0;
 
 	if (tqspi->cur_direction & DATA_DIR_TX) {
 		if (tqspi->tx_status) {
-			dmaengine_terminate_all(tqspi->tx_dma_chan);
-			err += 1;
-		} else {
+			if (tqspi->tx_dma_chan)
+				dmaengine_terminate_all(tqspi->tx_dma_chan);
+			num_errors++;
+		} else if (tqspi->tx_dma_chan) {
 			wait_status = wait_for_completion_interruptible_timeout(
 				&tqspi->tx_dma_complete, QSPI_DMA_TIMEOUT);
 			if (wait_status <= 0) {
 				dmaengine_terminate_all(tqspi->tx_dma_chan);
 				dev_err(tqspi->dev, "failed TX DMA transfer\n");
-				err += 1;
+				num_errors++;
 			}
 		}
 	}
 
 	if (tqspi->cur_direction & DATA_DIR_RX) {
 		if (tqspi->rx_status) {
-			dmaengine_terminate_all(tqspi->rx_dma_chan);
-			err += 2;
-		} else {
+			if (tqspi->rx_dma_chan)
+				dmaengine_terminate_all(tqspi->rx_dma_chan);
+			num_errors++;
+		} else if (tqspi->rx_dma_chan) {
 			wait_status = wait_for_completion_interruptible_timeout(
 				&tqspi->rx_dma_complete, QSPI_DMA_TIMEOUT);
 			if (wait_status <= 0) {
 				dmaengine_terminate_all(tqspi->rx_dma_chan);
 				dev_err(tqspi->dev, "failed RX DMA transfer\n");
-				err += 2;
+				num_errors++;
 			}
 		}
 	}
 
 	spin_lock_irqsave(&tqspi->lock, flags);
 
-	if (err) {
+	if (num_errors) {
 		tegra_qspi_dma_unmap_xfer(tqspi, t);
 		tegra_qspi_handle_error(tqspi);
 		complete(&tqspi->xfer_completion);
@@ -1444,9 +1481,9 @@ static irqreturn_t handle_dma_based_xfer(struct tegra_qspi *tqspi)
 	/* continue transfer in current message */
 	total_fifo_words = tegra_qspi_calculate_curr_xfer_param(tqspi, t);
 	if (total_fifo_words > QSPI_FIFO_DEPTH)
-		err = tegra_qspi_start_dma_based_transfer(tqspi, t);
+		num_errors = tegra_qspi_start_dma_based_transfer(tqspi, t);
 	else
-		err = tegra_qspi_start_cpu_based_transfer(tqspi, t);
+		num_errors = tegra_qspi_start_cpu_based_transfer(tqspi, t);
 
 exit:
 	spin_unlock_irqrestore(&tqspi->lock, flags);
@@ -1474,28 +1511,28 @@ static irqreturn_t tegra_qspi_isr_thread(int irq, void *context_data)
 }
 
 static struct tegra_qspi_soc_data tegra210_qspi_soc_data = {
-	.has_dma = true,
+	.has_ext_dma = true,
 	.cmb_xfer_capable = false,
 	.supports_tpm = false,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra186_qspi_soc_data = {
-	.has_dma = true,
+	.has_ext_dma = true,
 	.cmb_xfer_capable = true,
 	.supports_tpm = false,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra234_qspi_soc_data = {
-	.has_dma = false,
+	.has_ext_dma = false,
 	.cmb_xfer_capable = true,
 	.supports_tpm = true,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra241_qspi_soc_data = {
-	.has_dma = false,
+	.has_ext_dma = true,
 	.cmb_xfer_capable = true,
 	.supports_tpm = true,
 	.cs_count = 4,
-- 
2.17.1

Re: [PATCH v3] dt-bindings: spi: tegra: Document IOMMU property for Tegra234 QSPI

[Jon Hunter]

Hi all,

On 09/05/2025 13:35, Vishwaroop A wrote:
> Add the 'iommus' property to the Tegra QSPI device tree binding.
> The property is needed for Tegra234 when using the internal DMA
> controller, and is not supported on other Tegra chips, as DMA is
> handled by an external controller.
> 
> Signed-off-by: Vishwaroop A<va@nvidia.com>
> ---
>   .../bindings/spi/nvidia,tegra210-quad.yaml    | 19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)


Please ignore this revision. This is not versioned correctly, it is 
missing info on what changed since the last version. We will correct this.

Jon

-- 
nvpublic