board: rockchip: Add Radxa ROCK S0

Radxa ROCK S0 is a single-board computer based on the Rockchip RK3308B
SoC in an ultra-compact form factor. Add a board target for the board.

Features tested on a ROCK S0 v1.2 with 512 MiB RAM and 8 GiB eMMC:
- SD-card boot
- eMMC boot
- Ethernet
- USB gadget
- USB host

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

arch/arm/dts/rk3308-rock-s0-u-boot.dtsi

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include "rk3308-u-boot.dtsi"
+
+&emmc_pwren {
+	bootph-pre-ram;
+	bootph-some-ram;
+};
+
+&uart0 {
+	bootph-all;
+	clock-frequency = <24000000>;
+};
+
+&uart0_xfer {
+	bootph-all;
+};
+
+&vdd_core {
+	regulator-init-microvolt = <1015000>;
+};

board/rockchip/evb_rk3308/MAINTAINERS

@@ -12,3 +12,9 @@ R:      Jonas Karlman <jonas@kwiboo.se>
 S:      Maintained
 F:      configs/rock-pi-s-rk3308_defconfig
 F:      arch/arm/dts/rk3308-rock-pi-s*
+
+ROCK-S0
+M:      Jonas Karlman <jonas@kwiboo.se>
+S:      Maintained
+F:      configs/rock-s0-rk3308_defconfig
+F:      arch/arm/dts/rk3308-rock-s0*

configs/rock-s0-rk3308_defconfig

@@ -0,0 +1,72 @@
+CONFIG_ARM=y
+CONFIG_SKIP_LOWLEVEL_INIT=y
+CONFIG_COUNTER_FREQUENCY=24000000
+CONFIG_ARCH_ROCKCHIP=y
+CONFIG_DEFAULT_DEVICE_TREE="rockchip/rk3308-rock-s0"
+CONFIG_DM_RESET=y
+CONFIG_ROCKCHIP_RK3308=y
+CONFIG_TARGET_EVB_RK3308=y
+CONFIG_DEBUG_UART_BASE=0xFF0A0000
+CONFIG_DEBUG_UART_CLOCK=24000000
+# CONFIG_DEBUG_UART_BOARD_INIT is not set
+CONFIG_SYS_LOAD_ADDR=0xc00800
+CONFIG_DEBUG_UART=y
+CONFIG_ANDROID_BOOT_IMAGE=y
+CONFIG_FIT=y
+CONFIG_FIT_VERBOSE=y
+CONFIG_DEFAULT_FDT_FILE="rockchip/rk3308-rock-s0.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_GPIO=y
+CONFIG_CMD_GPT=y
+CONFIG_CMD_MMC=y
+CONFIG_CMD_USB=y
+CONFIG_CMD_ROCKUSB=y
+CONFIG_CMD_USB_MASS_STORAGE=y
+CONFIG_CMD_RNG=y
+CONFIG_CMD_KASLRSEED=y
+CONFIG_CMD_REGULATOR=y
+CONFIG_SPL_OF_CONTROL=y
+CONFIG_OF_LIVE=y
+CONFIG_OF_SPL_REMOVE_PROPS="clock-names interrupt-parent assigned-clocks assigned-clock-rates assigned-clock-parents"
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_REGMAP=y
+CONFIG_SYSCON=y
+CONFIG_CLK=y
+# CONFIG_USB_FUNCTION_FASTBOOT is not set
+CONFIG_ROCKCHIP_GPIO=y
+CONFIG_SYS_I2C_ROCKCHIP=y
+CONFIG_LED=y
+CONFIG_LED_GPIO=y
+CONFIG_ROCKCHIP_IODOMAIN=y
+CONFIG_SUPPORT_EMMC_RPMB=y
+CONFIG_MMC_DW=y
+CONFIG_MMC_DW_ROCKCHIP=y
+CONFIG_PHY_REALTEK=y
+CONFIG_DM_MDIO=y
+CONFIG_DM_ETH_PHY=y
+CONFIG_ETH_DESIGNWARE=y
+CONFIG_GMAC_ROCKCHIP=y
+CONFIG_PHY_ROCKCHIP_INNO_USB2=y
+CONFIG_PINCTRL=y
+CONFIG_REGULATOR_PWM=y
+CONFIG_DM_REGULATOR_FIXED=y
+CONFIG_PWM_ROCKCHIP=y
+CONFIG_RAM=y
+CONFIG_BAUDRATE=1500000
+CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_SYS_NS16550_MEM32=y
+CONFIG_SYSINFO=y
+CONFIG_SYSRESET=y
+CONFIG_USB=y
+CONFIG_DM_USB_GADGET=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_GENERIC=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_GADGET_DWC2_OTG=y
+CONFIG_USB_GADGET_DOWNLOAD=y
+CONFIG_USB_FUNCTION_ROCKUSB=y
+CONFIG_LZO=y
+CONFIG_ERRNO_STR=y

doc/board/rockchip/rockchip.rst

@@ -54,6 +54,7 @@ List of mainline supported Rockchip boards:
      - Amarula Vyasa-RK3288 (vyasa-rk3288)
 * rk3308
      - Radxa ROCK Pi S (rock-pi-s-rk3308)
+     - Radxa ROCK S0 (rock-s0-rk3308)
      - Rockchip Evb-RK3308 (evb-rk3308)
      - Roc-cc-RK3308 (roc-cc-rk3308)
 * rk3326