Device tree customization

Step 1: OEMs can create their own device tree by adding "qcom,msm-id/qcom,board-id" entry at the top of their file. The hardware variant ID has to be unique and created by the OEMs. Please refer to slides 10-13 in doc # 80-ND928-80. 

,
  DALCHIPINFO_ID_MSM8226    = 158,

boot_images\core\api\systemdrivers\DDIPlatformInfo.h
  ...
  DALPLATFORMINFO_TYPE_CDP          = 0x01, /**< Target is a MSM CDP/SURF device. */
  DALPLATFORMINFO_TYPE_MTP_MSM      = 0x08,  /**< Target is a MSM MTP device. */
  DALPLATFORMINFO_TYPE_QRD          = 0x0B,  /**< Target is a QRD device. */

DT Header

About dt.img format, please refer to dtbtool.txt and bootable\bootloader\lk\platform\msm_shared\smem.h
kernel\arch\arm\boot\dts\msm8226-cdp.dts
    model = "Qualcomm MSM 8226 CDP";
    compatible = "qcom,msm8226-cdp", "qcom,msm8226", "qcom,cdp";
    qcom,msm-id = <145 1 0>;
kernel\arch\arm\boot\dts\msm8226-mtp.dts
    model = "Qualcomm MSM 8226 MTP";
    compatible = "qcom,msm8226-mtp", "qcom,msm8226", "qcom,mtp";
    qcom,msm-id = <145 8 0>;
kernel\arch\arm\boot\dts\msm8226-qrd.dts
    model = "Qualcomm MSM 8226 QRD";
    compatible = "qcom,msm8226-qrd", "qcom,msm8226", "qcom,qrd";
    qcom,msm-id = <145 11 0>;

kernel\arch\arm\boot\dts\msm8916-qrd-skuh.dts
    model = "Qualcomm Technologies, Inc. MSM 8916 QRD SKUH";
    compatible = "qcom,msm8916-qrd-skuh", "qcom,msm8916-qrd", "qcom,msm8916", "qcom,qrd";
    qcom,board-id = <0x1000b 0> , <0x1000b 4>;
    
    Notes: Here subtype = 0/4; major version= 01 minor version = 00, platform type = 0b

CDT Description XML

boot_images\core\boot\secboot3\scripts\jedec_lpddr2_single_channel.xml
      <device id="cdb0">
        <props name="platform_id" type="DALPROP_ATTR_TYPE_BYTE_SEQ">
         
          0x03, 0x00, 0x00, 0x00, 0x00, 0x00, end
       
        </props>
      </device>

Example of 8x26 device
CDP:
0x03, 0x01, 0x01, 0x00, 0x00, 0x00, end
MTP:
0x03, 0x08, 0x01, 0x00, 0x00, 0x00, end
QRD:
0x03, 0x0B, 0x01, 0x00, 0x00, 0x00, end

Example of 8916 device
QRD SKUH:
0x03, 0x0B, 0x01, 0x00, 0x04, 0x00, end

Byte 0: platform_id Version
Byte 1: platform_id type:
           0x01: Target is a SURF device
           0x08: Target is a MTP device
           0x0B: Target is a QRD device
Byte 2: platform_id major platform version
Byte 3: platform_id minor platform version
Byte 4: platform_id subtype

What's you need do?

Generate CDT image and boot_cdt_array.c

• cd boot_images\core\boot\secboot3\scripts
• modify <jedec_lpddr2_single_channel.xml>
• python cdt_generator.py jedec_lpddr2_single_channel.xml  <cdt image>.bin

Program CDT image on device

cd boot_images/core/boot/secboot3/scripts/emmc_cdt_program_scripts
python ../../../../storage/tools/ptool/ptool.py  -x partition.xml -p 2
modify <jedec_lpddr2_single_channel.xml>

QRD HW V2:
0x03, 0x0B, 0x02, 0x00, 0x00, 0x00, end

python cdt_generator.py jedec_lpddr2_single_channel.xml  platform_ddr.bin
cp platform_ddr.bin emmc_cdt_program_scripts

T32
run platform_ddr_emmc_cdt_program.cmm
QPST
platform_ddr_prog_cfg.xml

Change default CDT in sbl1 image

• copy boot_cdt_array.c to boot_images\core\boot\secboot3\hw\msm8x26
• modify config_data_table[] in boot_cdt_array.c
• rebuild sbl1
• program sbl1 image

> fastboot flash sbl1 sb1.mbn or use QPST emmcdownload.exe

Generate DT Binary

• <modify dts>
• dtc -p 1024 -O dtb -o msm8626.dtb msm8626.dts
• cat zImage msm8626.dtb > boot.img
• program boot image

> fastboot flash boot boot.img

Temp workaround

After previous step, if the device still stop at LK(usb port fastboot),  you can try this temp workaround

bootable\bootloader\lk\platform\msm_shared\dev_tree.c
struct dt_entry * dev_tree_get_entry_ptr(struct dt_table *table)
{
<snip>                              
//workaround:  find out the DTB entry index from boot.img(or dt.img)

//                   change below code, force return expected expected dt_entry_ptr,

                               if((dt_entry_ptr->platform_id == board_platform_id()) /* &&

                               (dt_entry_ptr->variant_id == 1) &&

                               (dt_entry_ptr->soc_rev == 0)*/  )

                                               {

                                                                return dt_entry_ptr ++;

How to debug

When mismatch issue happens, lk normally will print error log with below format: 
ERROR: Unable to find suitable device tree for device ( [ chipset id ] [ soc version ] [ platform id type] [ platform subtype] ) 

for example as below 
ERROR: Unable to find suitable device tree for device (164/0x00010001/11/0) 

Match Procedure 
1. SBL will get chipset id, soc version from H/W regiser 
2. SBL fetch platform id type and platform subtype from CDT partitioin 
3. SBL write those information into share memory 
4. LK get those information and try to find suitable DTS entry. 

[chipset id] and [soc version]: 
For device: 
read from H/W register, can not modify 
For DTS: 
qcom,msm-id = <chipset_id, soc version> 

[Platform id type] and [platform subtype]: 
For device, defined in CDT xml file with below format: 
boot_images\core\boot\secboot3\scripts\jedec_lpddr2_single_channel.xml 
<device id="cdb0"> 
<props name="platform_id" type="DALPROP_ATTR_TYPE_BYTE_SEQ"> 

0x03, 0x0B, 0x01, 0x00, 0x04, 0x00, end 

</props> 
</device> 
Byte 0: platform_id Version 
Byte 1: platform_id type: 
0x01: Target is a SURF device 
0x08: Target is a MTP device 
0x0B: Target is a QRD device 
Byte 2: platform_id major platform version 
Byte 3: platform_id minor platform version 
Byte 4: platform_id subtype 
So what you need is to care about Byte 1 and Byte 4 
For DTS: 
qcom,board-id = <platform_id, subtype_id>