Project

General

Profile

SciphoneDreamG2 » History » Version 15

Anonymous, 02/19/2016 10:49 PM

1 1 laforge
= Sciphone Dream G2 =
2
3
The Sciphone Dream G2 is a [wiki:MT6235] based phone running UI software to mimic the look+feel of Android.
4
5
There is currently an u-boot and Linux port for the MT6235 underway, the primary development platform is the Sciphone G2.
6
7
OsmocomBB does not yet support any Mediatek chipsets, so this phone is not supported by OsmocomBB.  Nonetheless, we
8
expect to have support for it at some point in the future.
9
10 3 laforge
More information on the hardware of the device can be found at [http://en.qi-hardware.com/wiki/Sciphone_Dream_G2]
11 2 steve-m
== Serial Cable ==
12
13
You can make a serial cable by sacrificing the headset that comes with the phone, by swapping the pins inside the connector.
14
15
Serial pinout:
16
17 9 laforge
||Pin||signal||comment||
18 2 steve-m
||1||GND||
19
||2||GND||
20 9 laforge
||5||Rx||(From PC to Phone)||
21
||7||Tx||(From Phone to PC)||
22 2 steve-m
23
[[Image(sciphone_serial.jpg,20%)]]
24
25 1 laforge
== JTAG ==
26
27
The JTAG port of the MT6235 is accessible on the phone PCB, see the attached picture.
28 5 steve-m
You can use [http://openocd.berlios.de/web/ OpenOCD] along with the attached configuration file ([raw-attachment:openocd_mt6235.cfg]) for debugging.
29 4 steve-m
30 6 laforge
[[Image(scig2_front.JPG,20%)]]
31
[[Image(scig2_jtag.jpg,20%)]]
32
33 4 steve-m
== Serial Bootloader == 
34
35 5 steve-m
Like all Mediatek MT62xx !SoCs, the phone uses the [wiki:MTKRomloader].
36 6 laforge
37 10 steve-m
For executing U-Boot and Linux using the MTK romloader, proceed as follows:
38
39 11 steve-m
 * clone osmocom-bb.git and checkout the branch 'steve-m/loader_sciphone'
40 10 steve-m
 * compile the code, connect the phone and run osmocon:
41
   {{{
42 12 steve-m
$ ./osmocon -p /dev/ttyUSB0 -m mtk ../../target/firmware/board/mt62xx/loader.mtkram.bin
43 10 steve-m
   }}}
44
 * press and '''hold''' the powerbutton of the phone, until the loading has finished and you see the following:
45
   {{{
46
[...]
47
Received branch address ack, code should run now
48
49
Running on mt62xx in environment mtkram
50
HW_CODE = 0x6235
51
   }}}
52
53
'''Uploading U-Boot'''
54
 * '''don't''' terminate osmocon and execute:
55
 {{{
56
$ ./osmoload memload 0x500000 u-boot.bin
57
$ ./osmoload jump 0x500000
58
 }}}
59
60
 * now terminate osmocon and open a serial terminal of your choice (115200-8N1)
61
 * see below for loading Linux with U-Boot
62
63 13 laforge
== MTK boot process ==
64
65 15 laforge
[[Image(mt62xx_boot.jpg,20%)]]
66
67 14 laforge
MT62xx chips have IPL (Initial Program Loader) saved in ROM.[[BR]]
68 13 laforge
69
This is first code executed after power up.[[BR]]
70
71
It configures basic functionality of CPU (serial port 19200n8) and waits on 0xA beacon.[[BR]]
72
73
If beacon won't be received, it jumps to NAND memory read procedure.[[BR]]
74 1 laforge
75 15 laforge
At NAND 0x0 address Boot Header is placed which holds informations about NAND memory and parameters of image which is going to be loaded.[[BR]]
76 13 laforge
77
NAND memory read procedure tries to read NAND memory from 0x0 address with following NFI controller settings:
78
79
||Bus width||Address bytes||Page size||Column shift||Used in Sciphone G2||
80
||1||3||512||8||||
81
||0||3||512||8||||
82
||1||4||512||8||||
83
||0||4||512||8||yes||
84
||1||4||2048||16||||
85
||0||4||2048||16||yes||
86
||1||5||2048||16||||
87
||0||4||2048||16||||
88
89
If Boot Header read from NAND memory will match to currently used NFI configuration, bootloader will start to read data from NAND to internal SRAM. Internal SRAM size is 64kB, which means that code loaded by IPL can't be bigger than that.[[BR]]
90
91 14 laforge
'''Note:''' IPL doesn't configure PLL and SDRAM controller, so there is no possibility to load code to external RAM. Here is where SPL (Secondary Program Loader) comes into the game.
92 13 laforge
93
== SPL - Runing U-Boot from NAND ==
94
95 1 laforge
SPL (Second Program Loader) is just small U-Boot loader which includes low level CPU initialization (PLL, SDRAM) and NAND driver.[[BR]]
96 13 laforge
97 15 laforge
Using default build it occupies less than 4kB, but it lacks NAND memory detection. All the NAND memory types can be specified using preprocessor which is not comfortable. We already identified three different NAND memories and that would be bad to create seperate builds for them.[[BR]]
98 13 laforge
99
Fortunatelly there is no need to strip down SPL size to 4kB, so SPL code has been reworked and new functionalities are added. It detects NAND memory at startup and configures NFI controller automatically. New implementation can be found at "nand_spl/nand_boot_detect.c".[[BR]]
100
101
SPL also automatically configures SDRAM controler according to RAM you have on your device (currently it tries two configurations).[[BR]]
102 1 laforge
103
SPL is generated on every U-Boot build and binary can be found at "nand_spl/u-boot-spl.bin".[[BR]]
104 13 laforge
105 15 laforge
SPL will be loaded and executed by IPL only if Boot Header will contain valid data (in this case checksum and length is most important).[[BR]]
106 13 laforge
107 15 laforge
To generate Boot Header and place it at the begining of binary you should use mtk_image tool. MTK Boot Header generator can be found at "tools/mtk_image.c".
108 13 laforge
109
{{{
110
Usage ./mtk_image [ -s size ] [ -o file ] mtk_dump.bin image.bin
111
	[ -s size ]	- size of image, if not specified file size will be taken
112
	[ -o file ]	- name of output file
113 1 laforge
	mtk_dump.bin	- dump of NAND memory from address 0 (at least 64 bytes)
114 13 laforge
	image.bin	- image to be loaded by MTK bootloader
115 1 laforge
}}}
116
117 14 laforge
mtk_image tool needs dump file from your device (at least 64 bytes read from NAND 0x0 address) as there are different NAND memory configurations. Thanks to that Boot Header will be properly generated for your device.[[BR]]
118 13 laforge
119 14 laforge
'''Note! Before flashing U-Boot to NAND, create full dump of your NAND, otherwise you'll be not able to restore phone's original software.'''
120
121 6 laforge
== U-Boot ==
122
123
Port of U-Boot for Sciphone G2 can be found at [http://git.osmocom.org/gitweb?p=uboot-mt623x.git;a=summary U-Boot]
124
125
Building U-Boot:
126
127
{{{
128
export CROSS_COMPILE=arm-linux-gnueabi-
129
make sciphone_g2_config
130
make
131
}}}
132
133
== Linux kernel ==
134
135
Port of Linux kernel for Sciphone G2 can be found at [http://git.osmocom.org/gitweb?p=linux-mt623x.git;a=summary Linux kernel]
136
137
Building Linux:
138
139
{{{
140
export CROSS_COMPILE=arm-linux-gnueabi-
141 7 laforge
make ARCH=arm sciphone_g2_defconfig
142 6 laforge
make ARCH=arm uImage
143
}}}
144
145 8 laforge
== Building initramfs file system ==
146
147
The easiest way to have file system in Linux kernel is to build [http://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt Initramfs image].[[BR]]
148
149
You need to download [http://www.busybox.net/ Busybox], configure it and build it.
150
151
{{{
152
export CROSS_COMPILE=arm-linux-gnueabi-
153
make menuconfig
154
make
155 13 laforge
make install
156 8 laforge
}}}
157
158 13 laforge
Generated file system by default installs in _install directory.[[BR]]
159
160 8 laforge
Additional to that you'll need to create console device in already built filesystem.
161
162
{{{
163
sudo mknod dev/console c 5 1
164
}}}
165
166
Now you can create CPIO archive:
167
168
{{{
169
find . | cpio -o -H newc > rootfs.cpio
170
}}}
171
172
Next step is to point to Linux kernel where initramfs image is located.[[BR]]
173
174
In menuconfig of Linux kernel you should modify following option:
175
176
{{{
177
CONFIG_INITRAMFS_SOURCE=<path_to_cpio>
178
General setup -> Initial RAM filesystem and RAM disk -> Initramfs source file(s)
179
}}}
180
181
After these steps Linux kernel image will have initramfs built in.[[BR]]
182
183
'''Important note:''' Initramfs ignores 'init=' variable given in kernel boot parameters list. It always executes /init command at startup and you can't change it. Check if you have /init in your file system (BusyBox has /linuxrc by default, so just change its name to init).
184
Every time you change initramfs file system you have to rebuild also Linux kernel.[[BR]]
185
186
To unpack CPIO archive you can use following command:
187
188
{{{
189
cpio -i -d -H newc -F <path_to_cpio_archive> --no-absolute-filenames
190
}}}
191
192 6 laforge
== Reading data files in U-Boot ==
193
194
'''NAND'''
195
196 7 laforge
Following command will read 256 bytes from NAND address 0 at address 0x800000.
197 6 laforge
198
{{{
199 7 laforge
nand read 0x800000 0 0x100
200 6 laforge
}}}
201
202
'''Serial'''
203
204 7 laforge
Following command will read data at address 0x800000 from serial at baudrate 115200 (using kermit protocol).
205 6 laforge
206
{{{
207 7 laforge
loadb 0x800000 115200
208 6 laforge
}}}
209
210
'''SD/MMC'''
211 1 laforge
212 6 laforge
Following command will read uImage file at address 0x800000 from MMC card.
213 7 laforge
214 6 laforge
{{{
215 14 laforge
mmcinfo
216 7 laforge
fatload mmc 0 0x800000 uImage
217 13 laforge
}}}
218
219
== NAND memory ==
220
221
So far three types of NAND memories has been identified:
222
223
||Chip||Size||
224
||HY27XS08121M||512Mb (64MB) NAND||
225
||HY27XA081G1M||1Gb (128MB) NAND||
226
||TC58NVG0S3AFT||1Gb (128MB) NAND||
227
228
All of them are supported by "mt62xx_nand.c" NAND driver in U-Boot.[[BR]]
229
230
This driver has also support for ECC hardware decoding and encoding.[[BR]]
231
232
ECC layout which is used by MTK looks as follows:
233
234
{{{
235
/*
236
 * For small and large page NAND devices ecc block size is the same:
237
 *
238
 *      ecc_block_size = 256
239
 *
240
 * Placement of ecc bytes in spare area is as follows:
241
 *
242
 * --------------------------------------------------------------
243
 * |                            SPARE                           |
244
 * --------------------------------------------------------------
245
 * |    | ECC0  |       | ECC1  |       | ECC2  |       | ECC3  |
246
 * --------------------------------------------------------------
247
 * 0    8       16      24      32      40      48      56      64
248
 *
249
 * ECC0 = 12 bits (from 1st ECC block) + 12 bits (from 2nd ECC block)
250
 * ECC1 = 12 bits (from 3rd ECC block) + 12 bits (from 4th ECC block)
251
 * ECC2 = 12 bits (from 5th ECC block) + 12 bits (from 6th ECC block)
252
 * ECC2 = 12 bits (from 7th ECC block) + 12 bits (from 8th ECC block)
253
 */
254
255
}}}
256
257
ECC layout information is pretty important as built-in bootloader in MT62xx chips
258
has hardware ECC enabled and it won't load code from NAND if ECC layout will
259
not match.[[BR]]
260
261
This layout is also important to properly dump or restore existing firmware.[[BR]]
262
263
NAND driver for Linux is under development.
264
265
== LCD ==
266
Sciphone G2 has LCD with 240x320 resolution.[[BR]]
267
268
Currently two different LCD controllers has been identified (on Sciphone G2):
269
 * ILI9331
270
 * ILI9325
271
These controllers are already supported in U-Boot.[[BR]]
272
273
To identify what kind of controller is in your device, just check U-Boot prints.
274
275
{{{
276
DRAM:  32 MiB
277
NAND:  64 MiB
278
MMC:   msdc_mmc: 0
279
mtk_lcd INFO: Read LCD device code: 9331.
280
}}}
281
282
U-Boot supports displaying bitmap on the screen, you just have to create bitmap in proper format.[[BR]]
283
284
By default U-Boot will build osmocomBB bitmap.[[BR]]
285
286
To convert your customized bitmap change type of bitmap to indexed.[[BR]]
287
288
Using GIMP, select "Image -> Mode -> Indexed...". Maximum number of colours is 240 (16 is used by internal U-Boot CMAP).[[BR]]
289
290
In existing U-Boot bmp logo converting tool (tools/bmp_logo.c) there are two issues:
291
 * width of bitmap has to be aligned to 4 (otherwise padding bytes will be added and bitmap will be not properly displayed)
292
 * size of bitmap can't be bigger than 65535 (LCD on Sciphone G2 is 240x320 = 76800)
293
Both issues are fixed on [http://git.osmocom.org/gitweb?p=uboot-mt623x.git;a=summary uboot-mt623x].[[BR]]
294 1 laforge
295 13 laforge
MT6235 LCD controller shares data lines with NFI (NAND) controller. Currently there is no possibility to use NAND when LCD is used.[[BR]]
296
297
Frame buffer driver for Linux is under development.
298
299 14 laforge
== BBT handling ==
300 13 laforge
301
Comment from "sciphone_g2.h" configuration file explains how BBT is handled.
302
303
{{{
304
/*
305
 * Below option allows U-Boot to save BBT table in NAND.
306
 * Without this option BBT table is created everytime when first nand
307
 * command is executed (except "nand dump"). Full scanning of NAND
308
 * takes long time and unnecessarily delays first command execution.
309
 *
310
 * NOTE! This option is disabled by defaut as at startup it deletes last
311
 * two blocks of NAND. Most of people run code from RAM and don't have
312
 * NAND memory dumped yet. If you don't like to wait on first nand
313
 * command, you should enable below option.
314
 */
315
#define MT62XX_NAND_BBT_IN_NAND
316
}}}
317
318
== MTD partitions ==
319
320
Layout of MTD partitions is following:
321
322
{{{
323
device nand0 <mt62xx_nand.0>, # parts = 5
324
 #: name                size            offset          mask_flags
325
 0: sbl                 0x00020000      0x00000000      0
326
 1: env                 0x00020000      0x00020000      0
327
 2: u-boot              0x00200000      0x00040000      0
328
 3: kernel              0x00200000      0x00240000      0
329
 4: root                0x03bc0000      0x00440000      0
330 6 laforge
}}}
Add picture from clipboard (Maximum size: 48.8 MB)