board: intel: Add new slimbootloader board

Add slimbootloader board to run U-boot as a Slim Bootloader payload
- Add new board/intel/slimbootloader directory with minimum codes
- Add slimbootloader configuration files
- Add doc/board/intel/slimbootloader.rst

Signed-off-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: add slimbootloader board MAINTAINERS file]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

board/intel/Kconfig

@@ -73,6 +73,19 @@ config TARGET_MINNOWMAX
 	  Note that PCIE_ECAM_BASE is set up by the FSP so the value used
 	  by U-Boot matches that value.
 
+config TARGET_SLIMBOOTLOADER
+	bool "slimbootloader"
+	help
+	  This target is used for running U-Boot on top of Slim Bootloader
+	  boot firmware as a payload. Slim Bootloader does memory initialization
+	  and silicon initialization, and it passes necessary information in
+	  HOB (Hand Off Block) to a payload. The payload consumes HOB data
+	  which is generated by Slim Bootloader for its driver initialization.
+	  Slim Bootloader consumes FSP and its HOB, but FSP HOB is cleared
+	  Before launching a payload. Instead, Slim Bootloader generates its
+	  HOB data such as memory info, serial port info and so on.
+	  Refer to doc/board/intel/slimbootloader.rst for the details.
+
 endchoice
 
 source "board/intel/bayleybay/Kconfig"
@@ -82,5 +95,6 @@ source "board/intel/crownbay/Kconfig"
 source "board/intel/edison/Kconfig"
 source "board/intel/galileo/Kconfig"
 source "board/intel/minnowmax/Kconfig"
+source "board/intel/slimbootloader/Kconfig"
 
 endif

board/intel/slimbootloader/Kconfig

@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2019 Intel Corporation <www.intel.com>
+
+if TARGET_SLIMBOOTLOADER
+
+config SYS_BOARD
+	default "slimbootloader"
+
+config SYS_VENDOR
+	default "intel"
+
+config SYS_SOC
+	default "slimbootloader"
+
+config SYS_CONFIG_NAME
+	default "slimbootloader"
+
+config SYS_TEXT_BASE
+	default 0x00100000
+
+config BOARD_SPECIFIC_OPTIONS
+	def_bool y
+	select SYS_SLIMBOOTLOADER
+	select USB_STORAGE
+	select USB_KEYBOARD
+
+endif

board/intel/slimbootloader/MAINTAINERS

@@ -0,0 +1,6 @@
+Intel Slim Bootloader Payload
+M:	Aiden Park <aiden.park@intel.com>
+S:	Maintained
+F:	board/intel/slimbootloader
+F:	include/configs/slimbootloader.h
+F:	configs/slimbootloader_defconfig

board/intel/slimbootloader/Makefile

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2019 Intel Corporation <www.intel.com>
+
+obj-y	+= start.o slimbootloader.o

board/intel/slimbootloader/slimbootloader.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Intel Corporation <www.intel.com>
+ */
+
+#include <common.h>
+
+int board_early_init_r(void)
+{
+	/*
+	 * Make sure PCI bus is enumerated so that peripherals on the PCI bus
+	 * can be discovered by their drivers.
+	 *
+	 * Slim Bootloader has already done PCI bus enumeration before loading
+	 * U-Boot, so U-Boot needs to preserve PCI configuration.
+	 * Therefore, '# CONFIG_PCI_PNP is not set' is included in defconfig.
+	 */
+	pci_init();
+
+	return 0;
+}

board/intel/slimbootloader/start.S

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2019 Intel Corporation <www.intel.com>
+ */
+
+/* board early initialization */
+.globl early_board_init
+early_board_init:
+	jmp	early_board_init_ret