c101ae306d
A typical SPI operation consists of two phases - command and data
transfers. Command transfer is always from the host to the chip (i.e.
is going in the 'write' direction), data transfer could be either read
or write.
We don't want the receive FIFO to be operating while the command phase
is in progress. A simple way to keep the receive FIFO shut down is to
not to enable it until the command phase is completed.
Selective control of the receive FIFO allows to consolidate the
receive and transmit functions in a single spi_xfer() function, as it
happens in other SPI controller drivers.
The FIFO FULL and FIFO NOT EMPTY conditions are used to decide if the
next byte can be written or received, respectively. While data is
being received the 0xFF bytes are transmitted per each received byte,
to keep the SPI bus clocking.
The data structure describing the three GSBI ports is moved from the
.h file into .c file. A version of the clrsetbits macro is added to
work with integer addresses instead of pointers.
BUG=chrome-os-partner:27784
TEST=not yet, but with the res of the changes the bootblock loads and
starts the rombase section successfully.
Change-Id: I78cd0054f1a8f5e1d7213f38ef8de31486238aba
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/197779
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
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| .. | ||
| arch | ||
| console | ||
| cpu | ||
| device | ||
| drivers | ||
| ec | ||
| include | ||
| lib | ||
| mainboard | ||
| northbridge | ||
| soc | ||
| southbridge | ||
| superio | ||
| vendorcode | ||
| Kconfig | ||