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 seven RK3288 boards are supported: 40 41 - EVB RK3288 - use evb-rk3288 configuration 42 - Fennec RK3288 - use fennec-rk3288 configuration 43 - Firefly RK3288 - use firefly-rk3288 configuration 44 - Hisense Chromebook - use chromebook_jerry configuration 45 - Tinker RK3288 - use tinker-rk3288 configuration 46 - PopMetal RK3288 - use popmetal-rk3288 configuration 47 - Radxa Rock 2 - use rock2 configuration 48 49Two RK3036 board are supported: 50 51 - EVB RK3036 - use evb-rk3036 configuration 52 - Kylin - use kylin_rk3036 configuration 53 54For example: 55 56 CROSS_COMPILE=arm-linux-gnueabi- make O=firefly firefly-rk3288_defconfig all 57 58(or you can use another cross compiler if you prefer) 59 60 61Writing to the board with USB 62============================= 63 64For USB to work you must get your board into ROM boot mode, either by erasing 65your MMC or (perhaps) holding the recovery button when you boot the board. 66To erase your MMC, you can boot into Linux and type (as root) 67 68 dd if=/dev/zero of=/dev/mmcblk0 bs=1M 69 70Connect your board's OTG port to your computer. 71 72To create a suitable image and write it to the board: 73 74 ./firefly-rk3288/tools/mkimage -n rk3288 -T rkimage -d \ 75 ./firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 76 cat out | openssl rc4 -K 7c4e0304550509072d2c7b38170d1711 | rkflashtool l 77 78If all goes well you should something like: 79 80 U-Boot SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 10:06:49) 81 Card did not respond to voltage select! 82 spl: mmc init failed with error: -17 83 ### ERROR ### Please RESET the board ### 84 85You will need to reset the board before each time you try. Yes, that's all 86it does so far. If support for the Rockchip USB protocol or DFU were added 87in SPL then we could in principle load U-Boot and boot to a prompt from USB 88as several other platforms do. However it does not seem to be possible to 89use the existing boot ROM code from SPL. 90 91 92Booting from an SD card 93======================= 94 95To write an image that boots from an SD card (assumed to be /dev/sdc): 96 97 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 98 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 99 sudo dd if=out of=/dev/sdc seek=64 && \ 100 sudo dd if=firefly-rk3288/u-boot-dtb.img of=/dev/sdc seek=256 101 102This puts the Rockchip header and SPL image first and then places the U-Boot 103image at block 256 (i.e. 128KB from the start of the SD card). This 104corresponds with this setting in U-Boot: 105 106 #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR 256 107 108Put this SD (or micro-SD) card into your board and reset it. You should see 109something like: 110 111 U-Boot 2016.01-rc2-00309-ge5bad3b-dirty (Jan 02 2016 - 23:41:59 -0700) 112 113 Model: Radxa Rock 2 Square 114 DRAM: 2 GiB 115 MMC: dwmmc@ff0f0000: 0, dwmmc@ff0c0000: 1 116 *** Warning - bad CRC, using default environment 117 118 In: serial 119 Out: vop@ff940000.vidconsole 120 Err: serial 121 Net: Net Initialization Skipped 122 No ethernet found. 123 Hit any key to stop autoboot: 0 124 => 125 126The rockchip bootrom can load and boot an initial spl, then continue to 127load a second-level bootloader(ie. U-BOOT) as soon as it returns to bootrom. 128Therefore RK3288 has another loading sequence like RK3036. The option of 129U-Boot is controlled with this setting in U-Boot: 130 131 #define CONFIG_ROCKCHIP_SPL_BACK_TO_BROM 132 133You can create the image via the following operations: 134 135 ./firefly-rk3288/tools/mkimage -n rk3288 -T rksd -d \ 136 firefly-rk3288/spl/u-boot-spl-dtb.bin out && \ 137 cat firefly-rk3288/u-boot-dtb.bin >> out && \ 138 sudo dd if=out of=/dev/sdc seek=64 139 140If you have an HDMI cable attached you should see a video console. 141 142For evb_rk3036 board: 143 ./evb-rk3036/tools/mkimage -n rk3036 -T rksd -d evb-rk3036/spl/u-boot-spl.bin out && \ 144 cat evb-rk3036/u-boot-dtb.bin >> out && \ 145 sudo dd if=out of=/dev/sdc seek=64 146 147Note: rk3036 SDMMC and debug uart use the same iomux, so if you boot from SD, the 148 debug uart must be disabled 149 150 151Booting from an SD card on RK3188 152================================= 153 154For rk3188 boards the general storage onto the card stays the same as 155described above, but the image creation needs a bit more care. 156 157The bootrom of rk3188 expects to find a small 1kb loader which returns 158control to the bootrom, after which it will load the real loader, which 159can then be up to 29kb in size and does the regular ddr init. 160 161Additionally the rk3188 requires everything the bootrom loads to be 162rc4-encrypted. Except for the very first stage the bootrom always reads 163and decodes 2kb pages, so files should be sized accordingly. 164 165# copy tpl, pad to 1020 bytes and append spl 166cat tpl/u-boot-tpl.bin > tplspl.bin 167truncate -s 1020 tplspl.bin 168cat spl/u-boot-spl.bin >> tplspl.bin 169tools/mkimage -n rk3188 -T rksd -d tplspl.bin out 170 171# truncate, encode and append u-boot.bin 172truncate -s %2048 u-boot.bin 173cat u-boot.bin | split -b 512 --filter='openssl rc4 -K 7C4E0304550509072D2C7B38170D1711' >> out 174 175 176Using fastboot on rk3288 177======================== 178- Write GPT partition layout to mmc device which fastboot want to use it to 179store the image 180 181 => gpt write mmc 1 $partitions 182 183- Invoke fastboot command to prepare 184 185 => fastboot 1 186 187- Start fastboot request on PC 188 189 fastboot -i 0x2207 flash loader evb-rk3288/spl/u-boot-spl-dtb.bin 190 191You should see something like: 192 193 => fastboot 1 194 WARNING: unknown variable: partition-type:loader 195 Starting download of 357796 bytes 196 .. 197 downloading of 357796 bytes finished 198 Flashing Raw Image 199 ........ wrote 357888 bytes to 'loader' 200 201Booting from SPI 202================ 203 204To write an image that boots from SPI flash (e.g. for the Haier Chromebook): 205 206 ./chromebook_jerry/tools/mkimage -n rk3288 -T rkspi \ 207 -d chromebook_jerry/spl/u-boot-spl-dtb.bin spl.bin && \ 208 dd if=spl.bin of=spl-out.bin bs=128K conv=sync && \ 209 cat spl-out.bin chromebook_jerry/u-boot-dtb.img >out.bin && \ 210 dd if=out.bin of=out.bin.pad bs=4M conv=sync 211 212This converts the SPL image to the required SPI format by adding the Rockchip 213header and skipping every 2KB block. Then the U-Boot image is written at 214offset 128KB and the whole image is padded to 4MB which is the SPI flash size. 215The position of U-Boot is controlled with this setting in U-Boot: 216 217 #define CONFIG_SYS_SPI_U_BOOT_OFFS (128 << 10) 218 219If you have a Dediprog em100pro connected then you can write the image with: 220 221 sudo em100 -s -c GD25LQ32 -d out.bin.pad -r 222 223When booting you should see something like: 224 225 U-Boot SPL 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32) 226 227 228 U-Boot 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32 -0600) 229 230 Model: Google Jerry 231 DRAM: 2 GiB 232 MMC: 233 Using default environment 234 235 In: serial@ff690000 236 Out: serial@ff690000 237 Err: serial@ff690000 238 => 239 240Future work 241=========== 242 243Immediate priorities are: 244 245- USB host 246- USB device 247- Run CPU at full speed (code exists but we only see ~60 DMIPS maximum) 248- NAND flash 249- Support for other Rockchip parts 250- Boot U-Boot proper over USB OTG (at present only SPL works) 251 252 253Development Notes 254================= 255 256There are plenty of patches in the links below to help with this work. 257 258[1] https://github.com/rkchrome/uboot.git 259[2] https://github.com/linux-rockchip/u-boot-rockchip.git branch u-boot-rk3288 260[3] https://github.com/linux-rockchip/rkflashtool.git 261[4] http://wiki.t-firefly.com/index.php/Firefly-RK3288/Serial_debug/en 262 263rkimage 264------- 265 266rkimage.c produces an SPL image suitable for sending directly to the boot ROM 267over USB OTG. This is a very simple format - just the string RK32 (as 4 bytes) 268followed by u-boot-spl-dtb.bin. 269 270The boot ROM loads image to 0xff704000 which is in the internal SRAM. The SRAM 271starts at 0xff700000 and extends to 0xff718000 where we put the stack. 272 273rksd 274---- 275 276rksd.c produces an image consisting of 32KB of empty space, a header and 277u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although 278most of the fields are unused by U-Boot. We just need to specify the 279signature, a flag and the block offset and size of the SPL image. 280 281The header occupies a single block but we pad it out to 4 blocks. The header 282is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL 283image can be encoded too but we don't do that. 284 285The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB, 286or 0x40 blocks. This is a severe and annoying limitation. There may be a way 287around this limitation, since there is plenty of SRAM, but at present the 288board refuses to boot if this limit is exceeded. 289 290The image produced is padded up to a block boundary (512 bytes). It should be 291written to the start of an SD card using dd. 292 293Since this image is set to load U-Boot from the SD card at block offset, 294CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write 295u-boot-dtb.img to the SD card at that offset. See above for instructions. 296 297rkspi 298----- 299 300rkspi.c produces an image consisting of a header and u-boot-spl-dtb.bin. The 301resulting image is then spread out so that only the first 2KB of each 4KB 302sector is used. The header is the same as with rksd and the maximum size is 303also 32KB (before spreading). The image should be written to the start of 304SPI flash. 305 306See above for instructions on how to write a SPI image. 307 308rkmux.py 309-------- 310 311You can use this script to create #defines for SoC register access. See the 312script for usage. 313 314 315Device tree and driver model 316---------------------------- 317 318Where possible driver model is used to provide a structure to the 319functionality. Device tree is used for configuration. However these have an 320overhead and in SPL with a 32KB size limit some shortcuts have been taken. 321In general all Rockchip drivers should use these features, with SPL-specific 322modifications where required. 323 324GPT partition layout 325---------------------------- 326 327Rockchip use a unified GPT partition layout in open source support. 328With this GPT partition layout, uboot can be compatilbe with other components, 329like miniloader, trusted-os, arm-trust-firmware. 330 331There are some documents about partitions in the links below. 332http://rockchip.wikidot.com/partitions 333 334-- 335Simon Glass <sjg@chromium.org> 33624 June 2015 337