board: asus: transformer: add ASUS Transformer T20 family support

The Asus Eee Pad Transformer family are 2-in-1 detachable/slider
tablets developed by Asus that run the Android operating system.
The Eee Pad Transformers feature a 10.1-inch (260 mm) display,
an Nvidia Tegra 2 dual-core chip, 1 GB of RAM, and 16/32 GB of storage.
Transformers board derives from Nvidia Ventana development board.

This patch brings support for all 3 known T20 Transformers:
- Asus Eee Pad Transformer TF101
- Asus Eee Pad Transformer TF101G
- Asus Eee Pad Slider SL101

Tested-by: Robert Eckelmann <longnoserob@gmail.com> # ASUS TF101
Tested-by: Antoni Aloy Torrens <aaloytorrens@gmail.com> # ASUS TF101
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
diff --git a/configs/transformer_t20_defconfig b/configs/transformer_t20_defconfig
new file mode 100644
index 0000000..13bb269
--- /dev/null
+++ b/configs/transformer_t20_defconfig
@@ -0,0 +1,82 @@
+CONFIG_ARM=y
+CONFIG_ARCH_TEGRA=y
+CONFIG_SUPPORT_PASSING_ATAGS=y
+CONFIG_CMDLINE_TAG=y
+CONFIG_INITRD_TAG=y
+CONFIG_TEXT_BASE=0x00110000
+CONFIG_NR_DRAM_BANKS=2
+CONFIG_ENV_SIZE=0x3000
+CONFIG_ENV_OFFSET=0xFFFFD000
+CONFIG_DEFAULT_DEVICE_TREE="tegra20-asus-tf101"
+CONFIG_SPL_TEXT_BASE=0x00108000
+CONFIG_SPL_STACK=0xffffc
+CONFIG_TEGRA20=y
+CONFIG_TARGET_TRANSFORMER_T20=y
+CONFIG_TEGRA_ENABLE_UARTD=y
+CONFIG_CMD_EBTUPDATE=y
+CONFIG_SYS_LOAD_ADDR=0x2000000
+CONFIG_BUTTON_CMD=y
+CONFIG_BOOTDELAY=0
+CONFIG_AUTOBOOT_KEYED=y
+CONFIG_AUTOBOOT_KEYED_CTRLC=y
+CONFIG_OF_SYSTEM_SETUP=y
+CONFIG_BOOTCOMMAND="bootflow scan; poweroff"
+CONFIG_SYS_PBSIZE=2085
+CONFIG_SPL_FOOTPRINT_LIMIT=y
+CONFIG_SPL_MAX_FOOTPRINT=0x8000
+# CONFIG_SPL_SHARES_INIT_SP_ADDR is not set
+CONFIG_SPL_SYS_MALLOC=y
+CONFIG_SPL_HAS_CUSTOM_MALLOC_START=y
+CONFIG_SPL_CUSTOM_SYS_MALLOC_ADDR=0x90000
+CONFIG_SPL_SYS_MALLOC_SIZE=0x10000
+CONFIG_SYS_PROMPT="Tegra20 (Transformer) # "
+# CONFIG_CMD_BOOTEFI_BOOTMGR is not set
+CONFIG_CMD_BOOTMENU=y
+# CONFIG_CMD_IMI is not set
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_GPT=y
+CONFIG_CMD_GPT_RENAME=y
+CONFIG_CMD_I2C=y
+CONFIG_CMD_MMC=y
+CONFIG_CMD_POWEROFF=y
+CONFIG_CMD_USB=y
+CONFIG_CMD_USB_MASS_STORAGE=y
+CONFIG_CMD_UMS_ABORT_KEYED=y
+# CONFIG_CMD_SETEXPR is not set
+CONFIG_CMD_PAUSE=y
+CONFIG_CMD_EXT4_WRITE=y
+# CONFIG_SPL_DOS_PARTITION is not set
+# CONFIG_SPL_EFI_PARTITION is not set
+CONFIG_ENV_OVERWRITE=y
+CONFIG_ENV_IS_IN_MMC=y
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_SYS_MMC_ENV_PART=2
+CONFIG_BUTTON=y
+CONFIG_USB_FUNCTION_FASTBOOT=y
+CONFIG_FASTBOOT_BUF_ADDR=0x11000000
+CONFIG_FASTBOOT_BUF_SIZE=0x10000000
+CONFIG_FASTBOOT_FLASH=y
+CONFIG_FASTBOOT_FLASH_MMC_DEV=0
+CONFIG_FASTBOOT_CMD_OEM_FORMAT=y
+CONFIG_SYS_I2C_TEGRA=y
+CONFIG_BUTTON_KEYBOARD=y
+CONFIG_DM_PMIC=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_FIXED=y
+CONFIG_PWM_TEGRA=y
+CONFIG_SYS_NS16550=y
+CONFIG_USB=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_TEGRA=y
+CONFIG_USB_ULPI_VIEWPORT=y
+CONFIG_USB_ULPI=y
+CONFIG_USB_KEYBOARD=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_GADGET_MANUFACTURER="ASUS"
+CONFIG_USB_GADGET_VENDOR_NUM=0x0b05
+CONFIG_USB_GADGET_PRODUCT_NUM=0x4e0f
+CONFIG_CI_UDC=y
+CONFIG_VIDEO=y
+# CONFIG_VIDEO_LOGO is not set
+# CONFIG_VIDEO_BPP8 is not set
+CONFIG_VIDEO_TEGRA20=y