Add a few notes on how to try out the Rockchip support so far.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v4: - Tweak the cover letter a little, drop mention of patches already applied
Changes in v3: - Add various new patches to get RK3288 booting to a prompt - Update README to mention available drivers
Changes in v2: None
doc/README.rockchip | 246 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 246 insertions(+) create mode 100644 doc/README.rockchip
diff --git a/doc/README.rockchip b/doc/README.rockchip new file mode 100644 index 0000000..a34e198 --- /dev/null +++ b/doc/README.rockchip @@ -0,0 +1,246 @@ +# +# Copyright (C) 2015 Google. Inc +# Written by Simon Glass sjg@chromium.org +# +# SPDX-License-Identifier: GPL-2.0+ +# + +U-Boot on Rockchip +================== + +There are several repositories available with versions of U-Boot that support +many Rockchip devices [1] [2]. + +The current mainline support is experimental only and is not useful for +anything. It should provide a base on which to build. + +So far only support for the RK3288 is provided. + + +Prerequisites +============= + +You will need: + + - Firefly RK3288 baord + - Power connection to 5V using the supplied micro-USB power cable + - Separate USB serial cable attached to your computer and the Firefly + (connect to the micro-USB connector below the logo) + - rkflashtool [3] + - openssl (sudo apt-get install openssl) + - Serial UART connection [4] + - Suitable ARM cross compiler, e.g.: + sudo apt-get install gcc-4.7-arm-linux-gnueabi + + +Building +======== + +At present three RK3288 boards are supported: + + - Firefly RK3288 - use firefly-rk3288 configuration + - Radxa Rock Pro - also uses firefly-rk3288 configuration + - Haier Chromebook - use chromebook_jerry configuration + +For example: + + CROSS_COMPILE=arm-linux-gnueabi- make O=firefly firefly-rk3288_defconfig all + +(or you can use another cross compiler if you prefer) + +Note that the Radxa Rock Pro uses the Firefly configuration for now as +device tree files are not yet available for the Rock Pro. Clearly the two +have hardware differences, so this approach will break down as more drivers +are added. + + +Writing to the board with USB +============================= + +For USB to work you must get your board into ROM boot mode, either by erasing +your MMC or (perhaps) holding the recovery button when you boot the board. +To erase your MMC, you can boot into Linux and type (as root) + + dd if=/dev/zero of=/dev/mmcblk0 bs=1M + +Connect your board's OTG port to your computer. + +To create a suitable image and write it to the board: + + ./firefly-rk3288/tools/mkimage -T rkimage -d ./firefly-rk3288/spl/u-boot-spl-dtb.bin out + cat out | openssl rc4 -K 7c4e0304550509072d2c7b38170d1711 | rkflashtool l + +If all goes well you should something like: + + U-Boot SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 10:06:49) + Card did not respond to voltage select! + spl: mmc init failed with error: -17 + ### ERROR ### Please RESET the board ### + +You will need to reset the board before each time you try. Yes, that's all +it does so far. If support for the Rockchip USB protocol or DFU were added +in SPL then we could in principle load U-Boot and boot to a prompt from USB +as several other platforms do. However it does not seem to be possible to +use the existing boot ROM code from SPL. + + +Booting from an SD card +======================= + +To write an image that boots from an SD card (assumed to be /dev/sdc): + + ./firefly-rk3288/tools/mkimage -T rksd -d firefly-rk3288/spl/u-boot-spl-dtb.bin out + sudo dd if=out of=/dev/sdc + sudo dd if=firefly-rk3288/u-boot-dtb.img of=/dev/sdc seek=256 + +This puts the Rockchip header and SPL image first and then places the U-Boot +image at block 256 (i.e. 128KB from the start of the SD card). This +corresponds with this setting in U-Boot: + + #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR 256 + +Put this SD (or micro-SD) card into your board and reset it. You should see +something like: + + U-Boot SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 11:04:40) + + + U-Boot 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 11:04:40) + + DRAM: 2 GiB + MMC: + Using default environment + + In: serial@ff690000 + Out: serial@ff690000 + Err: serial@ff690000 + => + + +Booting from SPI +================ + +To write an image that boots from SPI flash (e.g. for the Haier Chromebook): + + ./chromebook_jerry/tools/mkimage -T rkspi -d chromebook_jerry/spl/u-boot-spl-dtb.bin out + dd if=spl.bin of=out.bin bs=128K conv=sync + cat chromebook_jerry/u-boot-dtb.img out.bin + dd if=out.bin of=out.bin.pad bs=4M conv=sync + +This converts the SPL image to the required SPI format by adding the Rockchip +header and skipping every 2KB block. Then the U-Boot image is written at +offset 128KB and the whole image is padded to 4MB which is the SPI flash size. +The position of U-Boot is controlled with this setting in U-Boot: + + #define CONFIG_SYS_SPI_U_BOOT_OFFS (128 << 10) + +If you have a Dediprog em100pro connected then you can write the image with: + + sudo em100 -s -c GD25LQ32 -d out.bin.pad -r + +When booting you should see something like: + + U-Boot SPL 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32) + + + U-Boot 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32 -0600) + + Model: Google Jerry + DRAM: 2 GiB + MMC: + Using default environment + + In: serial@ff690000 + Out: serial@ff690000 + Err: serial@ff690000 + => + + +Future work +=========== + +Immediate priorities are: + +- MMC support (in U-Boot itself) +- GPIO (driver exists but is lightly tested) +- I2C (driver exists but is non-functional) +- USB host +- USB device +- PMIC and regulators (only ACT8846 is supported at present) +- LCD and HDMI +- Run CPU at full speed +- Ethernet +- NAND flash +- Support for other Rockchip parts +- Boot U-Boot proper over USB OTG (at present only SPL works) + + +Development Notes +================= + +There are plenty of patches in the links below to help with this work. + +[1] https://github.com/rkchrome/uboot.git +[2] https://github.com/linux-rockchip/u-boot-rockchip.git branch u-boot-rk3288 +[3] https://github.com/linux-rockchip/rkflashtool.git +[4] http://wiki.t-firefly.com/index.php/Firefly-RK3288/Serial_debug/en + +rkimage +------- + +rkimage.c produces an SPL image suitable for sending directly to the boot ROM +over USB OTG. This is a very simple format - just the string RK32 (as 4 bytes) +followed by u-boot-spl-dtb.bin. + +The boot ROM loads image to 0xff704000 which is in the internal SRAM. The SRAM +starts at 0xff700000 and extends to 0xff718000 where we put the stack. + +rksd +---- + +rksd.c produces an image consisting of 32KB of empty space, a header and +u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although +most of the fields are unused by U-Boot. We just need to specify the +signature, a flag and the block offset and size of the SPL image. + +The header occupies a single block but we pad it out to 4 blocks. The header +is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL +image can be encoded too but we don't do that. + +The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB, +or 0x40 blocks. This is a severe and annoying limitation. There may be a way +around this limitation, since there is plenty of SRAM, but at present the +board refuses to boot if this limit is exceeded. + +The image produced is padded up to a block boundary (512 bytes). It should be +written to the start of an SD card using dd. + +Since this image is set to load U-Boot from the SD card at block offset, +CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write +u-boot-dtb.img to the SD card at that offset. See above for instructions. + +rkspi +----- + +rkspi.c produces an image consisting of a header and u-boot-spl-dtb.bin. The +resulting image is then spread out so that only the first 2KB of each 4KB +sector is used. The header is the same as with rksd and the maximum size is +also 32KB (before spreading). The image should be written to the start of +SPI flash. + +See above for instructions on how to write a SPI image. + + +Device tree and driver model +---------------------------- + +Where possible driver model is used to provide a structure to the +functionality. Device tree is used for configuration. However these have an +overhead and in SPL with a 32KB size limit some shortcuts have been taken. +In general all Rockchip drivers should use these features, with SPL-specific +modifications where required. + + +-- +Simon Glass sjg@chromium.org +24 June 2015