eMMC V5.1

Terms and definition

Address Space：

Mapped Host Address Space： 主机能够通过read command访问的设备内区域

CID:Device Identification register

MSB, LSB: Most Significant Bit or Least Significant Bit
OCR: Operation Conditions Register
open-drain: A logical interface operation mode. An external resistor or current source is used to pull the interface level to HIGH, the internal transistor pushes it to LOW
payload: Net data
push-pull: A logical interface operation mode, a complementary pair of transistors is used to push the interface level to HIGH or LOW.

UI: Unit Interval; It is one bit nominal time. For example, UI=5 ns at 200 MHz SDR, UI = 2.5 ns for 200MHz DDR.
UTC: Universal time coordinated
VDD: represents the common supply in case of a single supply device (VCC=VCCQ) or when related to consumed currents it represents the total consumed current for VCC and VCCQ.
VSS: Positive supply voltage ground for Core Device
VCC: Positive supply voltage for Core
VCCQ: Positive supply voltage for I/O
VSSQ: Positive supply voltage ground for I/O
Write Protection, Permanent: Write and erase prevention scheme, that once enabled, cannot be reversed.
Write Protection, Power-on: Write and erase prevention scheme, that once enabled, can only be reversed when a power failure event, that causes the device to reboot occurs, or the device is reset using the reset pin.
Write protection, Temporary: Write and erase prevention scheme that can be enabled and disabled.

 

6.6.18 Field Firmware Update

Field Firmware Update(FFU), 主机可以利用FFU来下载新版本的固件到eMMC device，下载完成后，指示eMMC安装新下载的固件。

开始FFU进程之前，host应检查SUPPORTED_MODE和FW_CONFIG field位于ext_csd.

SUPPORTED_MODES [493]
Bit [0]: ‘0’ FFU is not supported by the device. ‘1’ FFU is supported by the device.
Bit [1]: ‘0’ Vendor Specific Mode (VSM) is not supported by the device. ‘1’ Vendor Specific mode is supported by the device.

FW_CONFIG [169]

Bit[0]: Update_Disable
0x0: FW updates enabled.
0x1: FW update disabled permanently

如果device支持FFU，host通过切换ext_csd MODE CONFIG字段到FFU_MODE，来使能FFU。

在FFU_MODE下，host应该使用(cmd17/18/24/25)来下载新固件和读取vendor proprietary data。在这种模式下，

host应该使用定义在FFU_ARG字段的参数作为这些command的参数。否则，参数不对的话，download会失败。

7.4.16 FFU_ARG [490-487]
Using this field the device reports to the host the value that the host should set as an argument for the read and write commands in FFU mode.

主机可以通过将 EXT_CSD 中的 MODE_CONFIG 字段设置回正常状态来恢复写入和读取命令的常规功能。离开FFU会放弃固件下载操作。当重新回到固件下载时，应检查NUMBER_OF_FW_SECTORS_CORRECTLY_PROGRAMMED in the extended CSD，如果为0则重新下载，如果为正，则从下一个sector继续下载。

如果device支持MODE_OPERATION_CODES，host可以通过设置MODE_OPERATION_CODES为FFU_ABORT来放弃固件下载进程。

device会给host返回一个NUMBER...PROGRAMMED=0并且准备接受一个新的固件。