1# 2# Copyright (C) 2015 Google. Inc 3# Written by Simon Glass <sjg@chromium.org> 4# 5# SPDX-License-Identifier: GPL-2.0+ 6# 7 8U-Boot on Rockchip 9================== 10 11There are several repositories available with versions of U-Boot that support 12many Rockchip devices [1] [2]. 13 14The current mainline support is experimental only and is not useful for 15anything. It should provide a base on which to build. 16 17So far only support for the RK3288 and RK3036 is provided. 18 19 20Prerequisites 21============= 22 23You will need: 24 25 - Firefly RK3288 board or something else with a supported RockChip SoC 26 - Power connection to 5V using the supplied micro-USB power cable 27 - Separate USB serial cable attached to your computer and the Firefly 28 (connect to the micro-USB connector below the logo) 29 - rkflashtool [3] 30 - openssl (sudo apt-get install openssl) 31 - Serial UART connection [4] 32 - Suitable ARM cross compiler, e.g.: 33 sudo apt-get install gcc-4.7-arm-linux-gnueabi 34 35 36Building 37======== 38 39At present four RK3288 boards are supported: 40 41 - Firefly RK3288 - use firefly-rk3288 configuration 42 - Radxa Rock 2 - use rock2 configuration 43 - Hisense Chromebook - use chromebook_jerry configuration 44 - EVB RK3288 - use evb-rk3288 configuration 45 46Two RK3036 board are supported: 47 48 - EVB RK3036 - use evb-rk3036 configuration 49 - Kylin - use kylin_rk3036 configuration 50 51For example: 52 53 CROSS_COMPILE=arm-linux-gnueabi- make O=firefly firefly-rk3288_defconfig all 54 55(or you can use another cross compiler if you prefer) 56 57 58Writing to the board with USB 59============================= 60 61For USB to work you must get your board into ROM boot mode, either by erasing 62your MMC or (perhaps) holding the recovery button when you boot the board. 63To erase your MMC, you can boot into Linux and type (as root) 64 65 dd if=/dev/zero of=/dev/mmcblk0 bs=1M 66 67Connect your board's OTG port to your computer. 68 69To create a suitable image and write it to the board: 70 71 ./firefly-rk3288/tools/mkimage -n rk3288 -T rkimage -d \ 72 ./firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 73 cat out | openssl rc4 -K 7c4e0304550509072d2c7b38170d1711 | rkflashtool l 74 75If all goes well you should something like: 76 77 U-Boot SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 10:06:49) 78 Card did not respond to voltage select! 79 spl: mmc init failed with error: -17 80 ### ERROR ### Please RESET the board ### 81 82You will need to reset the board before each time you try. Yes, that's all 83it does so far. If support for the Rockchip USB protocol or DFU were added 84in SPL then we could in principle load U-Boot and boot to a prompt from USB 85as several other platforms do. However it does not seem to be possible to 86use the existing boot ROM code from SPL. 87 88 89Booting from an SD card 90======================= 91 92To write an image that boots from an SD card (assumed to be /dev/sdc): 93 94 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 95 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 96 sudo dd if=out of=/dev/sdc seek=64 && \ 97 sudo dd if=firefly-rk3288/u-boot-dtb.img of=/dev/sdc seek=256 98 99This puts the Rockchip header and SPL image first and then places the U-Boot 100image at block 256 (i.e. 128KB from the start of the SD card). This 101corresponds with this setting in U-Boot: 102 103 #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR 256 104 105Put this SD (or micro-SD) card into your board and reset it. You should see 106something like: 107 108 U-Boot 2016.01-rc2-00309-ge5bad3b-dirty (Jan 02 2016 - 23:41:59 -0700) 109 110 Model: Radxa Rock 2 Square 111 DRAM: 2 GiB 112 MMC: dwmmc@ff0f0000: 0, dwmmc@ff0c0000: 1 113 *** Warning - bad CRC, using default environment 114 115 In: serial 116 Out: vop@ff940000.vidconsole 117 Err: serial 118 Net: Net Initialization Skipped 119 No ethernet found. 120 Hit any key to stop autoboot: 0 121 => 122 123The rockchip bootrom can load and boot an initial spl, then continue to 124load a second-level bootloader(ie. U-BOOT) as soon as it returns to bootrom. 125Therefore RK3288 has another loading sequence like RK3036. The option of 126U-Boot is controlled with this setting in U-Boot: 127 128 #define CONFIG_ROCKCHIP_SPL_BACK_TO_BROM 129 130You can create the image via the following operations: 131 132 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 133 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 134 cat firefly-rk3288/u-boot-dtb.bin >> out && \ 135 sudo dd if=out of=/dev/sdc seek=64 136 137If you have an HDMI cable attached you should see a video console. 138 139For evb_rk3036 board: 140 ./evb-rk3036/tools/mkimage -n rk3036 -T rksd -d evb-rk3036/spl/u-boot-spl.bin out && \ 141 cat evb-rk3036/u-boot-dtb.bin >> out && \ 142 sudo dd if=out of=/dev/sdc seek=64 143 144Note: rk3036 SDMMC and debug uart use the same iomux, so if you boot from SD, the 145 debug uart must be disabled 146 147Booting from SPI 148================ 149 150To write an image that boots from SPI flash (e.g. for the Haier Chromebook): 151 152 ./chromebook_jerry/tools/mkimage -n rk3288 -T rkspi \ 153 -d chromebook_jerry/spl/u-boot-spl-dtb.bin spl.bin && \ 154 dd if=spl.bin of=spl-out.bin bs=128K conv=sync && \ 155 cat spl-out.bin chromebook_jerry/u-boot-dtb.img >out.bin && \ 156 dd if=out.bin of=out.bin.pad bs=4M conv=sync 157 158This converts the SPL image to the required SPI format by adding the Rockchip 159header and skipping every 2KB block. Then the U-Boot image is written at 160offset 128KB and the whole image is padded to 4MB which is the SPI flash size. 161The position of U-Boot is controlled with this setting in U-Boot: 162 163 #define CONFIG_SYS_SPI_U_BOOT_OFFS (128 << 10) 164 165If you have a Dediprog em100pro connected then you can write the image with: 166 167 sudo em100 -s -c GD25LQ32 -d out.bin.pad -r 168 169When booting you should see something like: 170 171 U-Boot SPL 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32) 172 173 174 U-Boot 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32 -0600) 175 176 Model: Google Jerry 177 DRAM: 2 GiB 178 MMC: 179 Using default environment 180 181 In: serial@ff690000 182 Out: serial@ff690000 183 Err: serial@ff690000 184 => 185 186 187Future work 188=========== 189 190Immediate priorities are: 191 192- USB host 193- USB device 194- Run CPU at full speed (code exists but we only see ~60 DMIPS maximum) 195- Ethernet 196- NAND flash 197- Support for other Rockchip parts 198- Boot U-Boot proper over USB OTG (at present only SPL works) 199 200 201Development Notes 202================= 203 204There are plenty of patches in the links below to help with this work. 205 206[1] https://github.com/rkchrome/uboot.git 207[2] https://github.com/linux-rockchip/u-boot-rockchip.git branch u-boot-rk3288 208[3] https://github.com/linux-rockchip/rkflashtool.git 209[4] http://wiki.t-firefly.com/index.php/Firefly-RK3288/Serial_debug/en 210 211rkimage 212------- 213 214rkimage.c produces an SPL image suitable for sending directly to the boot ROM 215over USB OTG. This is a very simple format - just the string RK32 (as 4 bytes) 216followed by u-boot-spl-dtb.bin. 217 218The boot ROM loads image to 0xff704000 which is in the internal SRAM. The SRAM 219starts at 0xff700000 and extends to 0xff718000 where we put the stack. 220 221rksd 222---- 223 224rksd.c produces an image consisting of 32KB of empty space, a header and 225u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although 226most of the fields are unused by U-Boot. We just need to specify the 227signature, a flag and the block offset and size of the SPL image. 228 229The header occupies a single block but we pad it out to 4 blocks. The header 230is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL 231image can be encoded too but we don't do that. 232 233The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB, 234or 0x40 blocks. This is a severe and annoying limitation. There may be a way 235around this limitation, since there is plenty of SRAM, but at present the 236board refuses to boot if this limit is exceeded. 237 238The image produced is padded up to a block boundary (512 bytes). It should be 239written to the start of an SD card using dd. 240 241Since this image is set to load U-Boot from the SD card at block offset, 242CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write 243u-boot-dtb.img to the SD card at that offset. See above for instructions. 244 245rkspi 246----- 247 248rkspi.c produces an image consisting of a header and u-boot-spl-dtb.bin. The 249resulting image is then spread out so that only the first 2KB of each 4KB 250sector is used. The header is the same as with rksd and the maximum size is 251also 32KB (before spreading). The image should be written to the start of 252SPI flash. 253 254See above for instructions on how to write a SPI image. 255 256rkmux.py 257-------- 258 259You can use this script to create #defines for SoC register access. See the 260script for usage. 261 262 263Device tree and driver model 264---------------------------- 265 266Where possible driver model is used to provide a structure to the 267functionality. Device tree is used for configuration. However these have an 268overhead and in SPL with a 32KB size limit some shortcuts have been taken. 269In general all Rockchip drivers should use these features, with SPL-specific 270modifications where required. 271 272 273-- 274Simon Glass <sjg@chromium.org> 27524 June 2015 276