xref: /openbmc/u-boot/doc/README.rockchip (revision c6e18144)
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 is provided.
18
19
20Prerequisites
21=============
22
23You will need:
24
25   - Firefly RK3288 baord
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 - also uses firefly-rk3288 configuration
43   - Haier Chromebook - use chromebook_jerry configuration
44
45one RK3036 board is support:
46
47   - EVB RK3036 - use evb-rk3036_defconfig configuration
48
49For example:
50
51   CROSS_COMPILE=arm-linux-gnueabi- make O=firefly firefly-rk3288_defconfig all
52
53(or you can use another cross compiler if you prefer)
54
55Note that the Radxa Rock 2 uses the Firefly configuration for now as
56device tree files are not yet available for the Rock 2. Clearly the two
57have hardware differences, so this approach will break down as more drivers
58are added.
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 SPL 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 11:04:40)
112
113
114   U-Boot 2015.07-rc1-00383-ge345740-dirty (Jun 03 2015 - 11:04:40)
115
116   DRAM:  2 GiB
117   MMC:
118   Using default environment
119
120   In:    serial@ff690000
121   Out:   serial@ff690000
122   Err:   serial@ff690000
123   =>
124
125For evb_rk3036 board:
126	./evb-rk3036/tools/mkimage -n rk3036 -T rksd  -d evb-rk3036/spl/u-boot-spl.bin out && \
127	cat evb-rk3036/u-boot-dtb.bin >> out && \
128	sudo dd if=out of=/dev/sdc seek=64
129
130Note: rk3036 SDMMC and debug uart use the same iomux, so if you boot from SD, the
131      debug uart must be disabled
132
133Booting from SPI
134================
135
136To write an image that boots from SPI flash (e.g. for the Haier Chromebook):
137
138   ./chromebook_jerry/tools/mkimage -n rk3288 -T rkspi \
139	-d chromebook_jerry/spl/u-boot-spl-dtb.bin spl.bin && \
140   dd if=spl.bin of=spl-out.bin bs=128K conv=sync && \
141   cat spl-out.bin chromebook_jerry/u-boot-dtb.img >out.bin && \
142   dd if=out.bin of=out.bin.pad bs=4M conv=sync
143
144This converts the SPL image to the required SPI format by adding the Rockchip
145header and skipping every 2KB block. Then the U-Boot image is written at
146offset 128KB and the whole image is padded to 4MB which is the SPI flash size.
147The position of U-Boot is controlled with this setting in U-Boot:
148
149   #define CONFIG_SYS_SPI_U_BOOT_OFFS	(128 << 10)
150
151If you have a Dediprog em100pro connected then you can write the image with:
152
153      sudo em100 -s -c GD25LQ32 -d out.bin.pad -r
154
155When booting you should see something like:
156
157   U-Boot SPL 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32)
158
159
160   U-Boot 2015.07-rc2-00215-g9a58220-dirty (Jun 23 2015 - 12:11:32 -0600)
161
162   Model: Google Jerry
163   DRAM:  2 GiB
164   MMC:
165   Using default environment
166
167   In:    serial@ff690000
168   Out:   serial@ff690000
169   Err:   serial@ff690000
170   =>
171
172
173Future work
174===========
175
176Immediate priorities are:
177
178- GPIO (driver exists but is lightly tested)
179- I2C (driver exists but is non-functional)
180- USB host
181- USB device
182- PMIC and regulators (only ACT8846 is supported at present)
183- LCD and HDMI
184- Run CPU at full speed
185- Ethernet
186- NAND flash
187- Support for other Rockchip parts
188- Boot U-Boot proper over USB OTG (at present only SPL works)
189
190
191Development Notes
192=================
193
194There are plenty of patches in the links below to help with this work.
195
196[1] https://github.com/rkchrome/uboot.git
197[2] https://github.com/linux-rockchip/u-boot-rockchip.git branch u-boot-rk3288
198[3] https://github.com/linux-rockchip/rkflashtool.git
199[4] http://wiki.t-firefly.com/index.php/Firefly-RK3288/Serial_debug/en
200
201rkimage
202-------
203
204rkimage.c produces an SPL image suitable for sending directly to the boot ROM
205over USB OTG. This is a very simple format - just the string RK32 (as 4 bytes)
206followed by u-boot-spl-dtb.bin.
207
208The boot ROM loads image to 0xff704000 which is in the internal SRAM. The SRAM
209starts at 0xff700000 and extends to 0xff718000 where we put the stack.
210
211rksd
212----
213
214rksd.c produces an image consisting of 32KB of empty space, a header and
215u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although
216most of the fields are unused by U-Boot. We just need to specify the
217signature, a flag and the block offset and size of the SPL image.
218
219The header occupies a single block but we pad it out to 4 blocks. The header
220is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL
221image can be encoded too but we don't do that.
222
223The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB,
224or 0x40 blocks. This is a severe and annoying limitation. There may be a way
225around this limitation, since there is plenty of SRAM, but at present the
226board refuses to boot if this limit is exceeded.
227
228The image produced is padded up to a block boundary (512 bytes). It should be
229written to the start of an SD card using dd.
230
231Since this image is set to load U-Boot from the SD card at block offset,
232CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write
233u-boot-dtb.img to the SD card at that offset. See above for instructions.
234
235rkspi
236-----
237
238rkspi.c produces an image consisting of a header and u-boot-spl-dtb.bin. The
239resulting image is then spread out so that only the first 2KB of each 4KB
240sector is used. The header is the same as with rksd and the maximum size is
241also 32KB (before spreading). The image should be written to the start of
242SPI flash.
243
244See above for instructions on how to write a SPI image.
245
246
247Device tree and driver model
248----------------------------
249
250Where possible driver model is used to provide a structure to the
251functionality. Device tree is used for configuration. However these have an
252overhead and in SPL with a 32KB size limit some shortcuts have been taken.
253In general all Rockchip drivers should use these features, with SPL-specific
254modifications where required.
255
256
257--
258Simon Glass <sjg@chromium.org>
25924 June 2015
260