TS-7180 FRAM

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This platform supports a soldered-down, non-volatile Ferroelectric RAM (FRAM) device. The Cypress FM25L16B is a 2 KiB FRAM device in a configuration not unlike an SPI EEPROM. The nature of FRAM means it is non-volatile, incredibly fast to write, and is specified with 100 trillion read/write cycles (per each of the 256 sequential 8 byte rows) with a 150 year data retention at temperatures below 65 °C. The device is connected to Linux and presents itself as a flat file that can be read and written like any standard Linux file.


The FRAM can be accessed as a flat file from Linux: 

# xxd -a /sys/class/spi_master/spi2/spi2.2/eeprom | head
00000000: 0000 0000 0000 0000 0000 0000 0000 0000  ................
*
000007f0: 0000 0000 0000 0000 0000 0000 0000 0030  ...............0

If U-Boot's bootcount tracking environment variable is enabled, the last byte of FRAM is reserved for storing the boot count, and care should be taken to not overwrite it inadvertently. In U-Boot, the boot count can be accessed with the fram command.

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