Boot EMMC¶

• Table of contents
• Boot EMMC
  • • EMMC Layout
    • Steps
  • Hardware Reset setting
    • From linux
    • From U-Boot
  • Enabling boot partitions from u-boot

NOTE: The AM62x has multiple MMC interfaces. The EMMC is configured on MMC1

To boot the Dev Kit from EMMC using a CL supplied image, set the boot pins as follows:
Reference: TRM Section 5.3 "Boot Mode Pins"

B9	B8	B7	B6	B5	B4	B3
Reserved (X)	Reserved (X)	Reserved (X)	1	0	0	1

Based on the TI wiki procedure ( https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/08_03_00_19/exports/docs/linux/Foundational_Components/U-Boot/UG-Memory.html )

EMMC Layout¶

             boot0 partition (4 MB)                        user partition
     0x0+----------------------------------+      0x0+-------------------------+
        |      tiboot3.bin (512 KB)        |         |                         |
  0x8000+----------------------------------+         |                         |
        |        tispl.bin (2 MB)          |         |                         |
0x280000+----------------------------------+         |        rootfs           |
        |      u-boot.img (1.412 MB)       |         |                         |
0x3E1000+----------------------------------+         |                         |
        |      environment (124 KB)        |         |                         |
0x400000+----------------------------------+         +-------------------------+

Steps¶

• Optional: Run through Clearing_the_eMMC if you want to test flashing a clean eMMC
• Boot to linux using a valid sd card image
• Make the partition label
  

  root@mitysom-am62x:~# parted /dev/mmcblk0 mklabel gpt
  

• Make the partiton
  

  root@mitysom-am62x:~# parted /dev/mmcblk0 mkpart primary ext4 0% 100%
  

• Print the newly created partition
  

  root@mitysom-am62x:~# parted /dev/mmcblk0 print
  Model: MMC KC3032 (sd/mmc)
  Disk /dev/mmcblk0: 31.3GB
  Sector size (logical/physical): 512B/512B
  Partition Table: gpt
  Disk Flags:
  
  Number  Start   End     Size    File system  Name     Flags
   1      1049kB  31.3GB  31.3GB               primary
  
  

• Manually mount the partition or Reboot
  

  root@mitysom-am62x:~# mkfs.ext4 /dev/mmcblk0p1
  root@mitysom-am62x:~# mkdir /run/media/mmcblk0p1
  root@mitysom-am62x:~# mount /dev/mmcblk0p1 /run/media/mmcblk0p1
  
  or
  
  root@mitysom-am62x:~# reboot
  

• Check the partition table
  

  *root@mitysom-am62x:~# lsblk
  NAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
  mmcblk0      179:0    0 58.3G  0 disk
  `-mmcblk0p1  179:1    0 58.3G  0 part /run/media/mmcblk0p1
  mmcblk0boot0 179:32   0    4M  1 disk
  mmcblk0boot1 179:64   0    4M  1 disk
  mmcblk1      179:96   0 29.8G  0 disk
  |-mmcblk1p1  179:97   0  128M  0 part /run/media/boot-mmcblk1p1
  `-mmcblk1p2  179:98   0 29.7G  0 part /*
  

• enable writing to the mmcblk0boot0 partition
  

  root@mitysom-am62x:~# echo 0 > /sys/block/mmcblk0boot0/force_ro
  

• Copy the needed images from the SD card to the eMMC boot partition
  

  root@mitysom-am62x:~# cd /run/media/boot-mmcblk1p1
  root@mitysom-am62x:~# dd if=tiboot3.bin of=/dev/mmcblk0boot0 bs=512 seek=0
  root@mitysom-am62x:~# dd if=tispl.bin of=/dev/mmcblk0boot0 bs=512 seek=1024
  root@mitysom-am62x:~# dd if=u-boot.img  of=/dev/mmcblk0boot0 bs=512 seek=5120
  

• Enable the boot partition of the eMMC device
  

  root@mitysom-am62x:~# mmc bootpart enable 1 1 /dev/mmcblk0
  root@mitysom-am62x:~# mmc bootbus set single_backward x1 x8 /dev/mmcblk0
  

• Copy the filesystem
  Note: Copying the tisdk-default image takes about 3 minutes
  

  root@mitysom-am62x:~# mkdir -p /mnt/sd-rootfs
  root@mitysom-am62x:~# mount /dev/mmcblk1p2 /mnt/sd-rootfs
  root@mitysom-am62x:~# cp -a /mnt/sd-rootfs/* /run/media/mmcblk0p1
  

  
  Note We do not recommend copying a live/booted filesystem as a way of imaging/copying a system. As written this provides an easy way to show the emmc works but it should be rewritten to program the emmc using outputs from yocto.

• Power off the board
  

  root@mitysom-am62x:~# poweroff
  

• Set the boot mode to boot from the eMMC and remove the SD card
  SW1 BM7-0 = x1001xxx
  SW2 BM15-8 = 000000xx

• Toggle S1 to power on the board, and you should successfully boot to the login prompt.
• Check to make sure we have booted from eMMC
  

  root@mitysom-am62x:~# lsblk
  NAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
  mmcblk0      179:0    0 58.3G  0 disk
  `-mmcblk0p1  179:1    0 58.3G  0 part /    <----- */ should be on eMMC partition*
  mmcblk0boot0 179:32   0    4M  1 disk
  mmcblk0boot1 179:64   0    4M  1 disk
  

• To test if eMMC fallback is functional, Toggle S1 to turn off the board, insert the SD card, power on and you should boot to linux.
• Run the following command
  

  root@mitysom-am62x:~# lsblk
  NAME         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
  mmcblk0      179:0    0 58.3G  0 disk
  `-mmcblk0p1  179:1    0 58.3G  0 part /run/media/mmcblk0p1
  mmcblk0boot0 179:32   0    4M  1 disk
  mmcblk0boot1 179:64   0    4M  1 disk
  mmcblk1      179:96   0 29.8G  0 disk
  |-mmcblk1p1  179:97   0  128M  0 part /run/media/boot-mmcblk1p1
  `-mmcblk1p2  179:98   0 29.7G  0 part /    <----- */ should be on MMC partition*
  

For regular development and potentially production programming, the eMMC can be programmed over USB. See Snagboot Boot and Flash eMMC Instructions

Hardware Reset setting¶

NOTE: We enable hw reset in our factory test environment, setting this yourself should not be necessary.

The eMMC part ships with hardware reset disabled. This caused reset/reboot to hang when booting from the eMMC.
To fix this, the HW reset needs to be enabled in the part. This is done by writing a 1 to the RST_N_FUNCTION CSD register in the part.
THIS IS A ONE-TIME-PROGRAMMABLE VALUE
If you write a 2 to this register, you will permanently DISABLE reset and effectively prevent using the eMMC as a boot device.

From linux¶

root@mitysom-am62x:~# mmc hwreset enable /dev/mmcblk0

The state of this register can be checked using the extcsd read command

root@mitysom-am62x:~# mmc extcsd read /dev/mmcblk0 | grep RST
H/W reset function [RST_N_FUNCTION]: 0x01

From U-Boot¶

mmc rst-function 0 1

Enabling boot partitions from u-boot¶

In addition, the emmc boot partitions can also be enabled from u-boot

mmc partconf 0 1 1 1
mmc bootbus 0 2 0 0