board: rockchip: Add minimal generic RK3528 board

Add a minimal generic RK3528 board that only have eMMC and SD-card
enabled. This defconfig can be used to boot from eMMC or SD-card on most
RK3528 boards that follow reference board design.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

arch/arm/dts/rk3528-generic-u-boot.dtsi

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+#include "rk3528-u-boot.dtsi"
+
+&sdmmc {
+	bus-width = <4>;
+	cap-sd-highspeed;
+	disable-wp;
+	no-mmc;
+	no-sdio;
+	status = "okay";
+};

arch/arm/dts/rk3528-generic.dts

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Minimal generic DT for RK3528 with eMMC enabled
+ */
+
+/dts-v1/;
+#include "rk3528.dtsi"
+
+/ {
+	model = "Generic RK3528";
+	compatible = "rockchip,rk3528";
+
+	chosen {
+		stdout-path = "serial0:1500000n8";
+	};
+};
+
+&sdhci {
+	bus-width = <8>;
+	cap-mmc-highspeed;
+	no-sd;
+	no-sdio;
+	non-removable;
+	status = "okay";
+};
+
+&uart0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&uart0m0_xfer>;
+	status = "okay";
+};

arch/arm/mach-rockchip/rk3528/MAINTAINERS

@@ -0,0 +1,5 @@
+GENERIC-RK3528
+M:	Jonas Karlman <jonas@kwiboo.se>
+S:	Maintained
+F:	arch/arm/dts/rk3528-generic*
+F:	configs/generic-rk3528_defconfig

configs/generic-rk3528_defconfig

@@ -0,0 +1,40 @@
+CONFIG_ARM=y
+CONFIG_SKIP_LOWLEVEL_INIT=y
+CONFIG_COUNTER_FREQUENCY=24000000
+CONFIG_ARCH_ROCKCHIP=y
+CONFIG_DEFAULT_DEVICE_TREE="rk3528-generic"
+CONFIG_ROCKCHIP_RK3528=y
+CONFIG_SYS_LOAD_ADDR=0xc00800
+CONFIG_DEBUG_UART_BASE=0xFF9F0000
+CONFIG_DEBUG_UART_CLOCK=24000000
+CONFIG_DEBUG_UART=y
+# CONFIG_BOOTMETH_VBE is not set
+CONFIG_DEFAULT_FDT_FILE="rockchip/rk3528-generic.dtb"
+# CONFIG_DISPLAY_CPUINFO is not set
+CONFIG_SPL_MAX_SIZE=0x40000
+CONFIG_SPL_PAD_TO=0x7f8000
+# CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
+CONFIG_CMD_MEMINFO=y
+CONFIG_CMD_MEMINFO_MAP=y
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_GPT=y
+CONFIG_CMD_MISC=y
+CONFIG_CMD_MMC=y
+# CONFIG_CMD_SETEXPR is not set
+CONFIG_CMD_RNG=y
+# CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_OF_UPSTREAM is not set
+CONFIG_OF_SPL_REMOVE_PROPS="clock-names interrupt-parent assigned-clocks assigned-clock-rates assigned-clock-parents"
+CONFIG_NO_NET=y
+# CONFIG_ADC is not set
+CONFIG_ROCKCHIP_GPIO=y
+CONFIG_SUPPORT_EMMC_RPMB=y
+CONFIG_MMC_DW=y
+CONFIG_MMC_DW_ROCKCHIP=y
+CONFIG_MMC_SDHCI=y
+CONFIG_MMC_SDHCI_SDMA=y
+CONFIG_MMC_SDHCI_ROCKCHIP=y
+CONFIG_BAUDRATE=1500000
+CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_SYS_NS16550_MEM32=y
+CONFIG_ERRNO_STR=y

doc/board/rockchip/rockchip.rst

@@ -97,6 +97,9 @@ List of mainline supported Rockchip boards:
      - Rockchip Evb-RK3399 (evb_rk3399)
      - Theobroma Systems RK3399-Q7 SoM - Puma (puma_rk3399)
 
+* rk3528
+     - Generic RK3528 (generic-rk3528)
+
 * rk3566
      - Anbernic RGxx3 (anbernic-rgxx3-rk3566)
      - FriendlyElec NanoPi R3S (nanopi-r3s-rk3566)
@@ -258,6 +261,15 @@ To build rk3399 boards:
         make evb-rk3399_defconfig
         make CROSS_COMPILE=aarch64-linux-gnu-
 
+To build rk3528 boards:
+
+.. code-block:: bash
+
+        export BL31=../rkbin/bin/rk35/rk3528_bl31_v1.18.elf
+        export ROCKCHIP_TPL=../rkbin/bin/rk35/rk3528_ddr_1056MHz_v1.10.bin
+        make generic-rk3528_defconfig
+        make CROSS_COMPILE=aarch64-linux-gnu-
+
 To build rk3568 boards:
 
 .. code-block:: bash