[PATCH] arm64: dts: rockchip: Add DT overlay to use Sige5 SD slot for SPI flashing

[Alexey Charkov]

ArmSoM Sige5, just as most RK3576 based boards, has its SD card pins
multiplexed with the FSPI1 controller, allowing for high-speed SPI access
to flash chips. If one has a microSD breakout board, a voltage regulator
to provide the necessary 1.8V power, a 6x5mm flash socket, and some jumper
wires, it's possible to use this to flash SPI chips directly from the
Sige5 with full hardware acceleration.

Add a DT overlay to set up the necessary pinmux and enable the FSPI1
controller for this purpose. This is specifically targeted at 1.8V flash
chips, and relies on an external regulator or power supply to provide the
necessary 1.8V power to the flash chip.

Signed-off-by: Alexey Charkov <alchark at flipper.net>
---
 arch/arm64/boot/dts/rockchip/Makefile              |  5 ++
 .../rk3576-armsom-sige5-fspi1-flasher.dtso         | 80 ++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/Makefile b/arch/arm64/boot/dts/rockchip/Makefile
index cb55c6b70d0e..ece5bdb387bc 100644
--- a/arch/arm64/boot/dts/rockchip/Makefile
+++ b/arch/arm64/boot/dts/rockchip/Makefile
@@ -166,6 +166,7 @@ dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3568-wolfvision-pf5-display-vz.dtbo
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3568-wolfvision-pf5-io-expander.dtbo
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-100ask-dshanpi-a1.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-armsom-sige5.dtb
+dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-armsom-sige5-fspi1-flasher.dtbo
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-armsom-sige5-v1.2-wifibt.dtbo
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-evb1-v10.dtb
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-evb1-v10-pcie1.dtbo
@@ -289,6 +290,10 @@ rk3568-wolfvision-pf5-vz-2-uhd-dtbs := rk3568-wolfvision-pf5.dtb \
 	rk3568-wolfvision-pf5-display-vz.dtbo \
 	rk3568-wolfvision-pf5-io-expander.dtbo
 
+dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-armsom-sige5-fspi1-flasher.dtb
+rk3576-armsom-sige5-fspi1-flasher-dtbs := rk3576-armsom-sige5.dtb \
+	rk3576-armsom-sige5-fspi1-flasher.dtbo
+
 dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3576-armsom-sige5-v1.2-wifibt.dtb
 rk3576-armsom-sige5-v1.2-wifibt-dtbs := rk3576-armsom-sige5.dtb \
 	rk3576-armsom-sige5-v1.2-wifibt.dtbo
diff --git a/arch/arm64/boot/dts/rockchip/rk3576-armsom-sige5-fspi1-flasher.dtso b/arch/arm64/boot/dts/rockchip/rk3576-armsom-sige5-fspi1-flasher.dtso
new file mode 100644
index 000000000000..b2ed735a43fc
--- /dev/null
+++ b/arch/arm64/boot/dts/rockchip/rk3576-armsom-sige5-fspi1-flasher.dtso
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * DT-overlay to use the SD card slot on the Sige5 for flashing SPI chips via
+ * the hardware FSPI1 controller.
+ *
+ * This is specifically targeted at 1.8V SPI flash chips, and requires an
+ * external regulator or power supply to provide the power to the flash chip,
+ * as the one on Sige5 is fixed at 3.3V.
+ *
+ * Here's an example circuit:
+ * -----------------------------------------------------------------
+ * SD card slot                    SPI flash chip (e.g. MX25U12832F)
+ * (Pin 1)    DAT2 <----------------------------> WP/SIO2    (Pin 3)
+ * (Pin 2) CD/DAT3 <----------------------------> RESET/SIO3 (Pin 7)
+ * (Pin 3)     CMD <----------------------------> CS#        (Pin 1)
+ * (Pin 5)     CLK <----------------------------> SCLK       (Pin 6)
+ * (Pin 7)    DAT0 <----------------------------> SI/SIO0    (Pin 5)
+ * (Pin 8)    DAT1 <----------------------------> SO/SIO1    (Pin 2)
+ *                           +-------+
+ * (Pin 4) 3V3 VDD <-> VIN 3 |MCP1700| 2 VOUT <-> 1V8 VCC    (Pin 8)
+ *                           +-------+
+ *                             1 GND
+ *                               |
+ * (Pin 6)     VSS <-------------+--------------> GND        (Pin 4)
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/pinctrl/rockchip.h>
+
+&{/} {
+	vcc3v3_sd_s0: regulator-vcc-3v3-sd {
+		compatible = "regulator-fixed";
+		pinctrl-0 = <&sdmmc0_pwren>;
+		pinctrl-names = "default";
+		regulator-name = "vcc3v3_sd_s0";
+		regulator-always-on;
+		regulator-boot-on;
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		enable-active-high;
+		gpios = <&gpio0 RK_PB6 GPIO_ACTIVE_HIGH>;
+		vin-supply = <&vcc_3v3_s3>;
+	};
+};
+
+&pinctrl {
+	sd {
+		sdmmc0_pwren: sdmmc0-pwren {
+			rockchip,pins = <0 RK_PB6 RK_FUNC_GPIO &pcfg_pull_none>;
+		};
+	};
+};
+
+&sfc1 {
+	pinctrl-0 = <&fspi1m0_csn0>, <&fspi1m0_pins>;
+	pinctrl-names = "default";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "okay";
+
+	flash at 0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <50000000>;
+		spi-rx-bus-width = <4>;
+		spi-tx-bus-width = <1>;
+		vcc-supply = <&vcc3v3_sd_s0>; /* Need a discrete LDO!!! */
+	};
+};
+
+&sdmmc {
+	status = "disabled";
+};
+
+&vccio_sd_s0 {
+	regulator-max-microvolt = <1800000>;
+};

---
base-commit: 7080e32d3f09d8688c4a87d81bdcc71f7f606b16
change-id: 20260424-sige5-flasher-e745282292bd

Best regards,
-- 
Alexey Charkov <alchark at flipper.net>