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 three 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 45Two RK3036 board are supported: 46 47 - EVB RK3036 - use evb-rk3036 configuration 48 - Kylin - use kylin_rk3036 configuration 49 50For example: 51 52 CROSS_COMPILE=arm-linux-gnueabi- make O=firefly firefly-rk3288_defconfig all 53 54(or you can use another cross compiler if you prefer) 55 56 57Writing to the board with USB 58============================= 59 60For USB to work you must get your board into ROM boot mode, either by erasing 61your MMC or (perhaps) holding the recovery button when you boot the board. 62To erase your MMC, you can boot into Linux and type (as root) 63 64 dd if=/dev/zero of=/dev/mmcblk0 bs=1M 65 66Connect your board's OTG port to your computer. 67 68To create a suitable image and write it to the board: 69 70 ./firefly-rk3288/tools/mkimage -n rk3288 -T rkimage -d \ 71 ./firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 72 cat out | openssl rc4 -K 7c4e0304550509072d2c7b38170d1711 | rkflashtool l 73 74If all goes well you should something like: 75 76 U-Boot SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 10:06:49) 77 Card did not respond to voltage select! 78 spl: mmc init failed with error: -17 79 ### ERROR ### Please RESET the board ### 80 81You will need to reset the board before each time you try. Yes, that's all 82it does so far. If support for the Rockchip USB protocol or DFU were added 83in SPL then we could in principle load U-Boot and boot to a prompt from USB 84as several other platforms do. However it does not seem to be possible to 85use the existing boot ROM code from SPL. 86 87 88Booting from an SD card 89======================= 90 91To write an image that boots from an SD card (assumed to be /dev/sdc): 92 93 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 94 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 95 sudo dd if=out of=/dev/sdc seek=64 && \ 96 sudo dd if=firefly-rk3288/u-boot-dtb.img of=/dev/sdc seek=256 97 98This puts the Rockchip header and SPL image first and then places the U-Boot 99image at block 256 (i.e. 128KB from the start of the SD card). This 100corresponds with this setting in U-Boot: 101 102 #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR 256 103 104Put this SD (or micro-SD) card into your board and reset it. You should see 105something like: 106 107 U-Boot 2016.01-rc2-00309-ge5bad3b-dirty (Jan 02 2016 - 23:41:59 -0700) 108 109 Model: Radxa Rock 2 Square 110 DRAM: 2 GiB 111 MMC: dwmmc@ff0f0000: 0, dwmmc@ff0c0000: 1 112 *** Warning - bad CRC, using default environment 113 114 In: serial 115 Out: vop@ff940000.vidconsole 116 Err: serial 117 Net: Net Initialization Skipped 118 No ethernet found. 119 Hit any key to stop autoboot: 0 120 => 121 122The rockchip bootrom can load and boot an initial spl, then continue to 123load a second-level bootloader(ie. U-BOOT) as soon as it returns to bootrom. 124Therefore RK3288 has another loading sequence like RK3036. The option of 125U-Boot is controlled with this setting in U-Boot: 126 127 #define CONFIG_ROCKCHIP_SPL_BACK_TO_BROM 128 129You can create the image via the following operations: 130 131 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 132 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 133 cat firefly-rk3288/u-boot-dtb.bin >> out && \ 134 sudo dd if=out of=/dev/sdc seek=64 135 136If you have an HDMI cable attached you should see a video console. 137 138For evb_rk3036 board: 139 ./evb-rk3036/tools/mkimage -n rk3036 -T rksd -d evb-rk3036/spl/u-boot-spl.bin out && \ 140 cat evb-rk3036/u-boot-dtb.bin >> out && \ 141 sudo dd if=out of=/dev/sdc seek=64 142 143Note: rk3036 SDMMC and debug uart use the same iomux, so if you boot from SD, the 144 debug uart must be disabled 145 146Booting from SPI 147================ 148 149To write an image that boots from SPI flash (e.g. for the Haier Chromebook): 150 151 ./chromebook_jerry/tools/mkimage -n rk3288 -T rkspi \ 152 -d chromebook_jerry/spl/u-boot-spl-dtb.bin spl.bin && \ 153 dd if=spl.bin of=spl-out.bin bs=128K conv=sync && \ 154 cat spl-out.bin chromebook_jerry/u-boot-dtb.img >out.bin && \ 155 dd if=out.bin of=out.bin.pad bs=4M conv=sync 156 157This converts the SPL image to the required SPI format by adding the Rockchip 158header and skipping every 2KB block. Then the U-Boot image is written at 159offset 128KB and the whole image is padded to 4MB which is the SPI flash size. 160The position of U-Boot is controlled with this setting in U-Boot: 161 162 #define CONFIG_SYS_SPI_U_BOOT_OFFS (128 << 10) 163 164If you have a Dediprog em100pro connected then you can write the image with: 165 166 sudo em100 -s -c GD25LQ32 -d out.bin.pad -r 167 168When booting you should see something like: 169 170 U-Boot SPL 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32) 171 172 173 U-Boot 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32 -0600) 174 175 Model: Google Jerry 176 DRAM: 2 GiB 177 MMC: 178 Using default environment 179 180 In: serial@ff690000 181 Out: serial@ff690000 182 Err: serial@ff690000 183 => 184 185 186Future work 187=========== 188 189Immediate priorities are: 190 191- USB host 192- USB device 193- Run CPU at full speed (code exists but we only see ~60 DMIPS maximum) 194- Ethernet 195- NAND flash 196- Support for other Rockchip parts 197- Boot U-Boot proper over USB OTG (at present only SPL works) 198 199 200Development Notes 201================= 202 203There are plenty of patches in the links below to help with this work. 204 205[1] https://github.com/rkchrome/uboot.git 206[2] https://github.com/linux-rockchip/u-boot-rockchip.git branch u-boot-rk3288 207[3] https://github.com/linux-rockchip/rkflashtool.git 208[4] http://wiki.t-firefly.com/index.php/Firefly-RK3288/Serial_debug/en 209 210rkimage 211------- 212 213rkimage.c produces an SPL image suitable for sending directly to the boot ROM 214over USB OTG. This is a very simple format - just the string RK32 (as 4 bytes) 215followed by u-boot-spl-dtb.bin. 216 217The boot ROM loads image to 0xff704000 which is in the internal SRAM. The SRAM 218starts at 0xff700000 and extends to 0xff718000 where we put the stack. 219 220rksd 221---- 222 223rksd.c produces an image consisting of 32KB of empty space, a header and 224u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although 225most of the fields are unused by U-Boot. We just need to specify the 226signature, a flag and the block offset and size of the SPL image. 227 228The header occupies a single block but we pad it out to 4 blocks. The header 229is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL 230image can be encoded too but we don't do that. 231 232The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB, 233or 0x40 blocks. This is a severe and annoying limitation. There may be a way 234around this limitation, since there is plenty of SRAM, but at present the 235board refuses to boot if this limit is exceeded. 236 237The image produced is padded up to a block boundary (512 bytes). It should be 238written to the start of an SD card using dd. 239 240Since this image is set to load U-Boot from the SD card at block offset, 241CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write 242u-boot-dtb.img to the SD card at that offset. See above for instructions. 243 244rkspi 245----- 246 247rkspi.c produces an image consisting of a header and u-boot-spl-dtb.bin. The 248resulting image is then spread out so that only the first 2KB of each 4KB 249sector is used. The header is the same as with rksd and the maximum size is 250also 32KB (before spreading). The image should be written to the start of 251SPI flash. 252 253See above for instructions on how to write a SPI image. 254 255rkmux.py 256-------- 257 258You can use this script to create #defines for SoC register access. See the 259script for usage. 260 261 262Device tree and driver model 263---------------------------- 264 265Where possible driver model is used to provide a structure to the 266functionality. Device tree is used for configuration. However these have an 267overhead and in SPL with a 32KB size limit some shortcuts have been taken. 268In general all Rockchip drivers should use these features, with SPL-specific 269modifications where required. 270 271 272-- 273Simon Glass <sjg@chromium.org> 27424 June 2015 275