board: add support for Minnowboard MAX

Very similar to the older Minnowboard, except that it works with mainline
Linux, uses 64bit firmware and a realtek NIC needing firmware.

The Linux configuration is based on the configuration fragment on elinux:
http://elinux.org/Minnowboard:MinnowMaxLinuxKernel

Many thanks to Circuitco for sponsoring a board.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/minnowboard-max/grub.cfg

@@ -0,0 +1,6 @@
+set default="0"
+set timeout="5"
+
+menuentry "Buildroot" {
+	linux /bzImage root=/dev/mmcblk0p2 rootwait console=tty0 console=ttyS0,115200
+}

board/minnowboard-max/linux-3.17.config

@@ -0,0 +1,47 @@
+CONFIG_NO_HZ=y
+CONFIG_SMP=y
+CONFIG_X86_INTEL_LPSS=y
+CONFIG_MATOM=y
+CONFIG_EFI=y
+CONFIG_PM_RUNTIME=y
+CONFIG_CPU_FREQ=y
+CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
+CONFIG_X86_INTEL_PSTATE=y
+CONFIG_X86_ACPI_CPUFREQ=y
+CONFIG_INTEL_IDLE=y
+CONFIG_IA32_EMULATION=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_CHR_DEV_SG=y
+CONFIG_ATA=y
+CONFIG_SATA_AHCI=y
+CONFIG_ATA_PIIX=y
+CONFIG_NETDEVICES=y
+CONFIG_R8169=y
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_8250_DW=y
+CONFIG_I2C_I801=y
+CONFIG_I2C_DESIGNWARE_PLATFORM=y
+CONFIG_I2C_DESIGNWARE_PCI=y
+CONFIG_SPI=y
+CONFIG_SPI_PXA2XX=y
+CONFIG_SPI_DESIGNWARE=y
+CONFIG_PINCTRL_BAYTRAIL=y
+CONFIG_GPIOLIB=y
+CONFIG_GPIO_SYSFS=y
+CONFIG_AGP=y
+CONFIG_DRM=y
+CONFIG_DRM_I915=y
+CONFIG_USB=y
+CONFIG_USB_XHCI_HCD=y
+CONFIG_NOP_USB_XCEIV=y
+CONFIG_MMC=y
+CONFIG_MMC_SDHCI=y
+CONFIG_MMC_SDHCI_PCI=y
+CONFIG_MMC_SDHCI_ACPI=y
+CONFIG_PWM=y
+CONFIG_PWM_LPSS=y
+CONFIG_EXT4_FS=y

board/minnowboard-max/post-build.sh

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+#!/bin/sh
+cp board/minnowboard-max/grub.cfg ${BINARIES_DIR}/efi-part/EFI/BOOT/grub.cfg

board/minnowboard-max/readme.txt

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+Prepare the SD card for the Minnow Board MAX
+============================================
+
+ 1. Partition the SD card with a GPT partition table
+
+    sudo cgdisk /dev/mmcblk0
+
+    Create two partitions:
+
+     a) First partition of a few dozens of megabytes, which will be
+        used to store the bootloader and the kernel image. Type must
+        be EF00 (EFI partition).
+
+     b) Second partition of any size, which will be used to store the
+        root filesystem. Type must be 8300 (Linux filesystem)
+
+ 2. Prepare the boot partition
+
+    We will format it, mount it, copy the EFI data generated by
+    Buildroot, and the kernel image.
+
+    sudo mkfs.vfat -F 32 -n boot /dev/mmcblk0p1
+    sudo mount /dev/mmcblk0p1 /mnt
+    sudo cp -a output/images/efi-part/* /mnt/
+    sudo cp output/images/bzImage /mnt/
+    sudo umount /mnt
+
+ 3. Prepare the root partition
+
+    We will format it, mount it, and extract the root filesystem.
+
+    sudo mkfs.ext4 -L root /dev/mmcblk0p2
+    sudo mount /dev/mmcblk0p2 /mnt
+    sudo tar -C /mnt -xf output/images/rootfs.tar
+    sudo umount /mnt
+
+ 4. Enjoy
+
+Additional information about this board can be found at
+http://www.minnowboard.org/ or http://elinux.org/Minnowboard:MinnowMax.

configs/minnowboard_max_defconfig

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+# Architecture
+BR2_x86_64=y
+BR2_x86_atom=y
+
+# Misc
+BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/minnowboard-max/post-build.sh"
+
+# Lock to 3.17 headers to avoid breaking with newer kernels
+BR2_KERNEL_HEADERS_VERSION=y
+BR2_DEFAULT_KERNEL_VERSION="3.17.2"
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_17=y
+
+# Needed for ethernet
+BR2_PACKAGE_LINUX_FIRMWARE=y
+BR2_PACKAGE_LINUX_FIRMWARE_RTL_8169=y
+
+# Linux kernel
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.17.2"
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/minnowboard-max/linux-3.17.config"
+
+# Bootloader
+BR2_TARGET_GRUB2=y
+BR2_TARGET_GRUB2_X86_64_EFI=y