Re: [PATCH 2/2] spi: Add Baikal-T1 System Boot SPI Controller driver

[Mark Brown]

On Tue, May 19, 2020 at 12:17:27AM +0300, Serge Semin wrote:

> Here is what we need to do to perform the EEPROM-read operation:
> 1) Enable EEPROM-read mode.
> 2) Initialize a corresponding registers with a number of SPI transfer words
>    (with bits-per-word taken into account) to read.
> 3) Push opcode + address + dummy bytes into the Tx FIFO. When it's done and
>    the Tx FIFO is empty, the controller will proceed with read operations by
>    pushing zeros (or ones, don't remember what level it's by default) to MOSI
>    and pulling data from MISO into the RX FIFO.
> 4) Keep up with getting data from the Rx FIFO so one wouldn't get overflown.

> Regarding programming write each time. Well, it's up to the driver implementation.
> If opcode, address, dummy bytes and number of words to read are the same as before,
> then re-programming isn't required.

Ah, nice.  This should be useful for far more than just flash - most
register reads will also be able to take advantage of this, they follow
a similar write then read pattern.

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