[PATCH] arch: riscv: thead: implement basic spi

[Kanak Shilledar <kanakshilledar@xxxxxxxxx>]

implemented basic spi support for TH1520 SoC.
created a fixed clock and a simple spi0 node.
updated the matching binding to include thead,th1520-spi as compatible.
added a spidev device in devicetree which will utilise the spi0 node.
this is usually reserved for a SPI NOR flash which is left unpopulated
underneath the carrier board. I performed a SPI self loop test using
tools/spi/spidev_test.c and tried sending `\xDE\xAD\xBE\xEF` and verified
it is being received correctly. i updated the of_device_id struct in
drivers/spi/spi-dw-mmio.c to include "thead,th1520-spi" as the compatible.
this patch also adds basic spi support on beaglev ahead which shares the
same TH1520 SoC. i have only tested on LicheePi 4A.

Signed-off-by: Kanak Shilledar <kanakshilledar@xxxxxxxxx>
---
 .../devicetree/bindings/spi/snps,dw-apb-ssi.yaml |  4 ++++
 .../boot/dts/thead/th1520-beaglev-ahead.dts      |  9 +++++++++
 .../boot/dts/thead/th1520-lichee-module-4a.dtsi  |  4 ++++
 .../riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 10 ++++++++++
 arch/riscv/boot/dts/thead/th1520.dtsi            | 16 ++++++++++++++++
 drivers/spi/spi-dw-mmio.c                        |  1 +
 6 files changed, 44 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
index fde3776a558b..bccd00a1ddd0 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
@@ -88,6 +88,10 @@ properties:
               - renesas,r9a06g032-spi # RZ/N1D
               - renesas,r9a06g033-spi # RZ/N1S
           - const: renesas,rzn1-spi   # RZ/N1
+      - description: T-HEAD TH1520 SoC SPI Controller
+        items:
+          - const: thead,th1520-spi
+          - const: snps,dw-apb-ssi
 
   reg:
     minItems: 1
diff --git a/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts b/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
index d9b4de9e4757..3103b74e0288 100644
--- a/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
+++ b/arch/riscv/boot/dts/thead/th1520-beaglev-ahead.dts
@@ -17,6 +17,7 @@ aliases {
 		gpio1 = &gpio1;
 		gpio2 = &gpio2;
 		gpio3 = &gpio3;
+		spi0 = &spi0;
 		serial0 = &uart0;
 		serial1 = &uart1;
 		serial2 = &uart2;
@@ -52,6 +53,10 @@ &sdhci_clk {
 	clock-frequency = <198000000>;
 };
 
+&spi_clk {
+	clock-frequency = <396000000>;
+};
+
 &uart_sclk {
 	clock-frequency = <100000000>;
 };
@@ -79,3 +84,7 @@ &sdio0 {
 &uart0 {
 	status = "okay";
 };
+
+&spi0 {
+	status = "okay";
+};
diff --git a/arch/riscv/boot/dts/thead/th1520-lichee-module-4a.dtsi b/arch/riscv/boot/dts/thead/th1520-lichee-module-4a.dtsi
index 1365d3a512a3..6939bd36560c 100644
--- a/arch/riscv/boot/dts/thead/th1520-lichee-module-4a.dtsi
+++ b/arch/riscv/boot/dts/thead/th1520-lichee-module-4a.dtsi
@@ -33,6 +33,10 @@ &sdhci_clk {
 	clock-frequency = <198000000>;
 };
 
+&spi_clk {
+	clock-frequency = <396000000>;
+};
+
 &uart_sclk {
 	clock-frequency = <100000000>;
 };
diff --git a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
index 9a3884a73e13..26f82fe91489 100644
--- a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
+++ b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
@@ -14,6 +14,7 @@ aliases {
 		gpio1 = &gpio1;
 		gpio2 = &gpio2;
 		gpio3 = &gpio3;
+		spi0 = &spi0;
 		serial0 = &uart0;
 		serial1 = &uart1;
 		serial2 = &uart2;
@@ -30,3 +31,12 @@ chosen {
 &uart0 {
 	status = "okay";
 };
+
+&spi0 {
+	status = "okay";
+	spidev@0 {
+		compatible = "rohm,dh2228fv";
+		reg = <0>;
+		spi-max-frequency = <500000>;
+	};
+};
diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
index d2fa25839012..f962de663e7e 100644
--- a/arch/riscv/boot/dts/thead/th1520.dtsi
+++ b/arch/riscv/boot/dts/thead/th1520.dtsi
@@ -140,6 +140,12 @@ apb_clk: apb-clk-clock {
 		#clock-cells = <0>;
 	};
 
+	spi_clk: spi-clock {
+		compatible = "fixed-clock";
+		clock-output-names = "spi_clk";
+		#clock-cells = <0>;
+	};
+
 	uart_sclk: uart-sclk-clock {
 		compatible = "fixed-clock";
 		clock-output-names = "uart_sclk";
@@ -183,6 +189,16 @@ clint: timer@ffdc000000 {
 					      <&cpu3_intc 3>, <&cpu3_intc 7>;
 		};
 
+		spi0: spi@ffe700c000 {
+			compatible = "thead,th1520-spi", "snps,dw-apb-ssi";
+			reg = <0xff 0xe700c000 0x0 0x1000>;
+			interrupts = <54 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&spi_clk>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "disabled";
+		};
+
 		uart0: serial@ffe7014000 {
 			compatible = "snps,dw-apb-uart";
 			reg = <0xff 0xe7014000 0x0 0x100>;
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 819907e332c4..39e3d46ebf5d 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -419,6 +419,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
 	{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
 	{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
 	{ .compatible = "amd,pensando-elba-spi", .data = dw_spi_elba_init},
+	{ .compatible = "thead,th1520-spi", .data = dw_spi_pssi_init},
 	{ /* end of table */}
 };
 MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
-- 
2.45.2