Booting from SPI flash

[veerendranathj]

Hi,

when we select booting from eSPI flash using configuration buttons... pre-boot loader (PBL) will initialize the communication between the booting medium(eSPI/eLBC/I2C/SD) to load RCW but according to following doc we are defining eSPI controller initialization in PBI commands... But how this is possible to load RCW before initializing eSPI...

Doc: http://www.nxp.com/files/training/doc/dwf/DWF13_APF_ENT_T0881.pdf

Thanks and Regards,

Veerendranath

[r8070z · Accepted solution]

Have a great day,

After reset the PBL uses eSPI interface with hardware wired settings. This only way to load RCW from the eSPI interface and start pre-boot initialization (PBI) from the eSPI interface. However during PBI from the eSPI interface the PBL can change the eSPI registers. Of course it is should be done carefully. So if you skip section:

#Initialize eSPI controller

09110000 80000403

09110020 2d170008

09110024 00100008

09110028 00100008

0911002c 00100008

the BPL still can load u-boot. I guess that main goal of the author was PBL command

09110020 2d17000

i.e. changing the SPMODE0 register in order to speed-up eSPI interface.

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[dbevans42]

What are the hardware wired settings used to load the RCW from eSPI interface?  Are these the default/reset values for the SPMODE0 register?  Specifically I am wondering does the data needs to be MSB or LSB first?  What is the clock speed used?

[veerendranathj]

Thanks.. :smileyhappy: