drivers: dma: siwx91x: Use DT to declare descriptors

Silabs siwx91x hardware use specific memory areas to store descriptors
for DMA requests. These areas are tightly coupled between the CPU and
the hardware. This helps in reducing the wait cycles.

Until now these addresses was also hard coded in the DT and in the
linker script. This patch leverage the zephyr,memory-region driver to
centralize the information in the DT.

Then, with this new implementation, the memory mapping is easier to
understand for the reader.

Signed-off-by: Jérôme Pouiller <[email protected]>

Author: jerome-pouiller

drivers/dma/dma_silabs_siwx91x.c

@@ -670,7 +670,7 @@ static DEVICE_API(dma, siwx91x_dma_api) = {
 		.clock_subsys = (clock_control_subsys_t)DT_INST_PHA(inst, clocks, clkid),          \
 		.reg = (UDMA0_Type *)DT_INST_REG_ADDR(inst),                                       \
 		.irq_number = DT_INST_PROP_BY_IDX(inst, interrupts, 0),                            \
-		.sram_desc_addr = (RSI_UDMA_DESC_T *)DT_INST_PROP(inst, silabs_sram_desc_addr),    \
+		.sram_desc_addr = DT_REG_ADDR(DT_INST_PHANDLE(inst, silabs_sram_region)),          \
 		.irq_configure = siwx91x_dma_irq_configure_##inst,                                 \
 	};                                                                                         \
 	DEVICE_DT_INST_DEFINE(inst, &siwx91x_dma_init, NULL, &dma_data_##inst, &dma_cfg_##inst,    \

dts/arm/silabs/siwg917.dtsi

@@ -6,6 +6,7 @@
 
 #include <arm/armv7-m.dtsi>
 #include <zephyr/dt-bindings/clock/silabs/siwx91x-clock.h>
+#include <zephyr/dt-bindings/memory-attr/memory-attr-arm.h>
 #include <freq.h>
 
 / {
@@ -27,9 +28,24 @@
 
 	sram0: memory@0 {
 		compatible = "mmio-sram";
+		/* remove sram_dma0 region at the end of the sram */
 		reg = <0x00000000 DT_SIZE_K(191)>;
 	};
 
+	sram_dma0: memory-dma@2fc00 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x0002fc00 DT_SIZE_K(1)>;
+		zephyr,memory-region = "dma0";
+		zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
+	};
+
+	sram_dma1: memory-dma@24061c00 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x24061c00 DT_SIZE_K(1)>;
+		zephyr,memory-region = "dma1";
+		zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
+	};
+
 	bt_hci0: bt_hci {
 		compatible = "silabs,siwx91x-bt-hci";
 		status = "disabled";
@@ -243,7 +259,7 @@
 			interrupts = <33 0>;
 			interrupt-names = "dma0";
 			clocks = <&clock0 SIWX91X_CLK_DMA0>;
-			silabs,sram-desc-addr = <0x2fc00>;
+			silabs,sram-region = <&sram_dma0>;
 			#dma-cells = < 1>;
 			dma-channels = <32>;
 			status = "disabled";
@@ -257,7 +273,7 @@
 			interrupts = <10 0>;
 			interrupt-names = "ulpdma";
 			clocks = <&clock0 SIWX91X_CLK_ULP_DMA>;
-			silabs,sram-desc-addr = <0x24061c00>;
+			silabs,sram-region = <&sram_dma1>;
 			#dma-cells = < 1>;
 			dma-channels = <12>;
 			status = "disabled";

dts/bindings/dma/silabs,siwx91x-dma.yaml

@@ -8,15 +8,12 @@ properties:
   reg:
     required: true
 
-  silabs,sram-desc-addr:
-    type: int
+  silabs,sram-region:
+    type: phandle
     required: true
     description: |
-        SRAM Address for UDMA Descriptor Storage. This address must correspond to the location
-        of the udma_addr0 section in the linker script for the dma0 node, and the udma_addr1
-        section for the ulpdma node. Ensure that the value specified for the SRAM address matches
-        the respective section defined in the linker file for each UDMA node, as this alignment
-        is critical for proper descriptor management and data transfer.
+        SRAM Address for UDMA Descriptor Storage. This address must match to the
+        location used by the hardware.
 
   "#dma-cells":
     const: 1

soc/silabs/silabs_siwx91x/siwg917/linker.ld

@@ -5,29 +5,10 @@
  */
 #include <zephyr/arch/arm/cortex_m/scripts/linker.ld>
 
-MEMORY
-{
-	udma0   (rwx)  : ORIGIN = 0x0002fc00, LENGTH = 0x00000400
-	udma1   (rwx)  : ORIGIN = 0x24061c00, LENGTH = 0x00000400
-}
-
 SECTIONS
 {
 	.common_tcm_code :
 	{
 		*(.common_tcm_code*)
 	} > FLASH
-
-	/* These regions of SRAM is where the UDMA descriptors are stored. The corresponding
-	   section must be properly declared in the linker script to ensure correct data transfer
-	   and proper functioning of the UDMA module */
-	.udma_addr0 :
-	{
-		*(.udma_addr0*)
-	} > udma0 AT> FLASH
-
-	.udma_addr1 :
-	{
-		*(.udma_addr1*)
-	} > udma1 AT> FLASH
 }