[PATCH 2/2] arm64: dts: rockchip: Enable SDIO Wi-Fi on NanoPi R2S Plus

[Deomid rojer Ryabkov <rojer@rojer.me>]

The NanoPi R2S Plus has an M.2 E-key slot wired to the sdmmc_ext
controller in 4-bit SDIO mode, where FriendlyElec fit an optional
Fn-Link 6222B-SRC (Realtek RTL8822CS) module:

  - SDIO signalling at a fixed 1.8V (VCC_18)
  - WIFI_REG_ON on GPIO3_B0, 32kHz sleep clock from the RK805 CLKOUT2

Enable the controller and add the power sequence. The SDIO pins need
8mA drive strength for SDR104 tuning to succeed, as in the vendor
device tree [1]; with the SoC default of 4mA no sample phase works.

On boards without the module the controller gives up after about 0.2s
("mmc2: Failed to initialize a non-removable card"); nothing else is
affected.

With the mmc core change for the module's CMD11 handling at a fixed
1.8V [2], the module is tuned to SDR104 at 150 MHz and works with the
rtw88_8822cs driver; without it, it runs in high-speed mode at 50 MHz.

[1] https://github.com/friendlyarm/kernel-rockchip/blob/9238df9d21e835bba35c8ba5248784387936cb2e/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2-rev24.dts#L144-L172
[2] https://lore.kernel.org/linux-mmc/20261023232813.2983368-1-rojer@rojer.me/
Signed-off-by: Deomid rojer Ryabkov <rojer@rojer.me>
---
 .../dts/rockchip/rk3328-nanopi-r2s-plus.dts   | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2s-plus.dts b/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2s-plus.dts
index 6ba4a74cb1f..db19a18ae45 100644
--- a/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2s-plus.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2s-plus.dts
@@ -17,6 +17,15 @@ / {
 	aliases {
 		mmc1 = &emmc;
 	};
+
+	sdio_pwrseq: sdio-pwrseq {
+		compatible = "mmc-pwrseq-simple";
+		clocks = <&rk805 1>;
+		clock-names = "ext_clock";
+		pinctrl-names = "default";
+		pinctrl-0 = <&wifi_reg_on_h>;
+		reset-gpios = <&gpio3 RK_PB0 GPIO_ACTIVE_LOW>;
+	};
 };
 
 &emmc {
@@ -34,3 +43,50 @@ &io_domains {
 	vccio4-supply = <&vcc_io_33>;
 	vccio6-supply = <&vcc_18>;
 };
+
+&pinctrl {
+	wifi {
+		wifi_reg_on_h: wifi-reg-on-h {
+			rockchip,pins = <3 RK_PB0 RK_FUNC_GPIO &pcfg_pull_none>;
+		};
+	};
+};
+
+/*
+ * SDR104 tuning fails with the default 4mA drive strength, use 8mA like the
+ * vendor device tree.
+ */
+&sdmmc0ext_bus4 {
+	rockchip,pins =
+		<3 RK_PA4 3 &pcfg_pull_up_8ma>,
+		<3 RK_PA5 3 &pcfg_pull_up_8ma>,
+		<3 RK_PA6 3 &pcfg_pull_up_8ma>,
+		<3 RK_PA7 3 &pcfg_pull_up_8ma>;
+};
+
+&sdmmc0ext_clk {
+	rockchip,pins = <3 RK_PA2 3 &pcfg_pull_none_8ma>;
+};
+
+&sdmmc0ext_cmd {
+	rockchip,pins = <3 RK_PA0 3 &pcfg_pull_up_8ma>;
+};
+
+/* Optional M.2 E-key SDIO Wi-Fi module (Fn-Link 6222B-SRC, RTL8822CS) */
+&sdmmc_ext {
+	bus-width = <4>;
+	cap-sd-highspeed;
+	cap-sdio-irq;
+	disable-wp;
+	keep-power-in-suspend;
+	mmc-pwrseq = <&sdio_pwrseq>;
+	no-mmc;
+	no-sd;
+	non-removable;
+	pinctrl-names = "default";
+	pinctrl-0 = <&sdmmc0ext_clk &sdmmc0ext_cmd &sdmmc0ext_bus4>;
+	sd-uhs-sdr104;
+	vmmc-supply = <&vcc_io_33>;
+	vqmmc-supply = <&vcc_18>;
+	status = "okay";
+};
-- 
2.53.0


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