Determine the number of DMA channels by 'dma-channels' property

The PDMA driver currently assumes there are four channels by default, it might cause the error if there is actually less than four channels. Change that by getting number of channel dynamically from device tree. For backwards-compatible, it uses the default value (i.e. 4) when there is no 'dma-channels' information in dts.

This patch set contains the dts and dt-bindings change.

Changed in v7:
- Rebase on tag v5.17-rc7
- Modify the subject of patch

Changed in v6:
- Rebase on tag v5.17-rc6
- Change sf_pdma.chans[] to a flexible array member.

Changed in v5:
- Rebase on tag v5.17-rc3
- Fix typo in dt-bindings and commit message
- Add PDMA versioning scheme for compatible

Changed in v4:
- Remove cflags of debug use reported-by: kernel test robot <[email protected]>

Changed in v3:
- Fix allocating wrong size
- Return error if 'dma-channels' is larger than maximum

Changed in v2:
- Rebase on tag v5.16
- Use 4 as default value of dma-channels

Zong Li (3):
dt-bindings: dma-engine: sifive,fu540: Add dma-channels property and
modify compatible
riscv: dts: Add dma-channels property and modify compatible
dmaengine: sf-pdma: Get number of channel by device tree

 .../bindings/dma/sifive,fu540-c000-pdma.yaml  | 19 +++++++++++++--
 .../boot/dts/microchip/microchip-mpfs.dtsi    |  3 ++-
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi    |  3 ++-
 drivers/dma/sf-pdma/sf-pdma.c                 | 24 ++++++++++++-------
 drivers/dma/sf-pdma/sf-pdma.h                 |  8 ++-----
 5 files changed, 39 insertions(+), 18 deletions(-)

2.31.1

Add dma-channels property, then we can determine how many channels there by device tree, rather than statically defining it in PDMA driver. In addition, we also modify the compatible for PDMA versioning scheme.

---
 .../bindings/dma/sifive,fu540-c000-pdma.yaml  | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

index 75ad898c59bc..92f410f54d72 100644
@@ -25,7 +25,15 @@ description: |
 properties:
   compatible:
     items:
-      - const: sifive,fu540-c000-pdma
+      - enum:
+          - sifive,fu540-c000-pdma
+      - const: sifive,pdma0
+    description:
+      Should be "sifive,<chip>-pdma" and "sifive,pdma<version>".
+      Supported compatible strings are -
+      "sifive,fu540-c000-pdma" for the SiFive PDMA v0 as integrated onto the
+      SiFive FU540 chip resp and "sifive,pdma0" for the SiFive PDMA v0 IP block
+      with no chip integration tweaks.
 
   reg:
     maxItems: 1

@@ -34,6 +42,12 @@ properties:
     minItems: 1
     maxItems: 8
 
+  dma-channels:
+    description: For backwards-compatibility, the default value is 4
+    minimum: 1
+    maximum: 4
+    default: 4
+
   '#dma-cells':
     const: 1
 

@@ -48,8 +62,9 @@ additionalProperties: false
 examples:
   - |
     dma@3000000 {
-      compatible = "sifive,fu540-c000-pdma";
+      compatible = "sifive,fu540-c000-pdma", "sifive,pdma0";
       reg = <0x3000000 0x8000>;
+      dma-channels = <4>;
       interrupts = <23>, <24>, <25>, <26>, <27>, <28>, <29>, <30>;
       #dma-cells = <1>;
     };

2.31.1

Best regards,
Krzysztof

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Add dma-channels property, then we can determine how many channels there by device tree, in addition, we add the pdma versioning scheme for compatible.

---
 arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi | 3 ++-
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi        | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

index 869aaf0d5c06..d8869ec99945 100644
@@ -187,11 +187,12 @@ plic: interrupt-controller@c000000 {
 		};
 
 		dma@3000000 {
-			compatible = "sifive,fu540-c000-pdma";
+			compatible = "sifive,fu540-c000-pdma", "sifive,pdma0";
 			reg = <0x0 0x3000000 0x0 0x8000>;
 			interrupt-parent = <&plic>;
 			interrupts = <23>, <24>, <25>, <26>, <27>, <28>, <29>,
 				     <30>;
+			dma-channels = <4>;
 			#dma-cells = <1>;
 		};
 

index 3eef52b1a59b..6a3011180846 100644
@@ -168,11 +168,12 @@ uart0: serial@10010000 {
 			status = "disabled";
 		};
 		dma: dma@3000000 {
-			compatible = "sifive,fu540-c000-pdma";
+			compatible = "sifive,fu540-c000-pdma", "sifive,pdma0";
 			reg = <0x0 0x3000000 0x0 0x8000>;
 			interrupt-parent = <&plic0>;
 			interrupts = <23>, <24>, <25>, <26>, <27>, <28>, <29>,
 				     <30>;
+			dma-channels = <4>;
 			#dma-cells = <1>;
 		};
 		uart1: serial@10011000 {

2.31.1

It currently assumes that there are always four channels, it would cause the error if there is actually less than four channels. Change that by getting number of channel from device tree.

For backwards-compatibility, it uses the default value (i.e. 4) when there is no 'dma-channels' information in dts.

---
 drivers/dma/sf-pdma/sf-pdma.c | 24 ++++++++++++++++--------
 drivers/dma/sf-pdma/sf-pdma.h |  8 ++------
 2 files changed, 18 insertions(+), 14 deletions(-)

index f12606aeff87..db5a4ef76077 100644
@@ -482,23 +482,30 @@ static void sf_pdma_setup_chans(struct sf_pdma *pdma)
 static int sf_pdma_probe(struct platform_device *pdev)
 {
 	struct sf_pdma *pdma;
-	struct sf_pdma_chan *chan;
 	struct resource *res;
-	int len, chans;
-	int ret;
+	int ret, n_chans;
 	const enum dma_slave_buswidth widths =
 		DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
 		DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
 		DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
 		DMA_SLAVE_BUSWIDTH_64_BYTES;
 
-	chans = PDMA_NR_CH;
-	len = sizeof(*pdma) + sizeof(*chan) * chans;
-	pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
+	ret = of_property_read_u32(pdev->dev.of_node, "dma-channels", &n_chans);
+	if (ret) {
+		/* backwards-compatibility for no dma-channels property */
+		dev_dbg(&pdev->dev, "set number of channels to default value: 4\n");
+		n_chans = PDMA_MAX_NR_CH;
+	} else if (n_chans > PDMA_MAX_NR_CH) {
+		dev_err(&pdev->dev, "the number of channels exceeds the maximum\n");
+		return -EINVAL;
+	}
+
+	pdma = devm_kzalloc(&pdev->dev, struct_size(pdma, chans, n_chans),
+			    GFP_KERNEL);
 	if (!pdma)
 		return -ENOMEM;
 
-	pdma->n_chans = chans;
+	pdma->n_chans = n_chans;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pdma->membase = devm_ioremap_resource(&pdev->dev, res);

@@ -556,7 +563,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
 	struct sf_pdma_chan *ch;
 	int i;
 
-	for (i = 0; i < PDMA_NR_CH; i++) {
+	for (i = 0; i < pdma->n_chans; i++) {
 		ch = &pdma->chans[i];
 
 		devm_free_irq(&pdev->dev, ch->txirq, ch);

@@ -574,6 +581,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
 
 static const struct of_device_id sf_pdma_dt_ids[] = {
 	{ .compatible = "sifive,fu540-c000-pdma" },
+	{ .compatible = "sifive,pdma0" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, sf_pdma_dt_ids);

index 0c20167b097d..dcb3687bd5da 100644
@@ -22,11 +22,7 @@
 #include "../dmaengine.h"
 #include "../virt-dma.h"
 
-#define PDMA_NR_CH					4
-
-#if (PDMA_NR_CH != 4)
-#error "Please define PDMA_NR_CH to 4"
-#endif
+#define PDMA_MAX_NR_CH					4
 
 #define PDMA_BASE_ADDR					0x3000000
 #define PDMA_CHAN_OFFSET				0x1000

@@ -118,7 +114,7 @@ struct sf_pdma {
 	void __iomem            *membase;
 	void __iomem            *mappedbase;
 	u32			n_chans;
-	struct sf_pdma_chan	chans[PDMA_NR_CH];
+	struct sf_pdma_chan	chans[];
 };
 
 #endif /* _SF_PDMA_H */

2.31.1


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