spi: Get rid of SPI_ATOMIC_SEQUENCING

SPI_ATOMIC_SEQUENCING was added to accomodate spi flash controllers with
the ability to perform tx and rx of flash command and response at the
same time. Instead of introducing this notion at SPI flash driver layer,
clean up the interface to SPI used by flash.

Flash uses a command-response kind of communication. Thus, even though
SPI is duplex, flash command needs to be sent out on SPI bus and then
flash response should be received on the bus. Some specialized x86
flash controllers are capable of handling command and response in a
single transaction.

In order to support all the varied cases:
1. Add spi_xfer_vector that takes as input a vector of SPI operations
and calls back into SPI controller driver to process these operations.
2. In order to accomodate flash command-response model, use two vectors
while calling into spi_xfer_vector -- one with dout set to
non-NULL(command) and other with din set to non-NULL(response).
3. For specialized SPI flash controllers combine two successive vectors
if the transactions look like a command-response pair.
4. Provide helper functions for common cases like supporting only 2
vectors at a time, supporting n vectors at a time, default vector
operation to cycle through all SPI op vectors one by one.

BUG=chrome-os-partner:59832
BRANCH=None
TEST=Compiles successfully

Change-Id: I4c9e78c585ad95c40c0d5af078ff8251da286236
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17681
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/src/soc/qualcomm/ipq40xx/Kconfig b/src/soc/qualcomm/ipq40xx/Kconfig
index f7386227d0..05f29e4be9 100644
--- a/src/soc/qualcomm/ipq40xx/Kconfig
+++ b/src/soc/qualcomm/ipq40xx/Kconfig
@@ -7,7 +7,6 @@ config SOC_QC_IPQ40XX
 	select ARCH_RAMSTAGE_ARMV7
 	select BOOTBLOCK_CONSOLE
 	select HAVE_UART_SPECIAL
-	select SPI_ATOMIC_SEQUENCING
 	select GENERIC_GPIO_LIB
 	select HAVE_MONOTONIC_TIMER