package: mmc-utils: Initial commit

[alistair23]

Add support for the mmc-utils package. This can be used to determine the life of the MMC, for example as described here: https://www.cnx-software.com/2019/08/16/wear-estimation-emmc-flash-memory/

This also completes part of: #9

[Eeems]

Installs and works for me on my rM1. Did you test on a rM2?

We probably should add some sort of helper script to parse the output and provide better health information. Most of it is vendor specific fields or just an overload of information to wrap your head around.

[Eeems]

The good news is, my device is still between 0-10% usage:

reMarkable: ~/packages/ mmc extcsd read /dev/mmcblk1 | grep -i LIFE
eMMC Life Time Estimation A [EXT_CSD_DEVICE_LIFE_TIME_EST_TYP_A]: 0x01
eMMC Life Time Estimation B [EXT_CSD_DEVICE_LIFE_TIME_EST_TYP_B]: 0x01
reMarkable: ~/packages/ mmc extcsd read /dev/mmcblk1 | grep -i EOL
eMMC Pre EOL information [EXT_CSD_PRE_EOL_INFO]: 0x01

Maybe some patches to add the vendor specific field handling would also be in order.

[alistair23]

I tested this on my rM2, so it works there.

I don't have plans to add scripts or vendor specific patches. Someone is welcome to add a script though. For vendor patches it's probably worth trying to send them upstream first.

I also see between 0-10% usage for my flash which is good :)