spi: Clean up SPI flash driver interface

RW flag was added to spi_slave structure to get around a requirement on
some AMD flash controllers that need to group together all spi volatile
operations (write/erase). This rw flag is not a property or attribute of
the SPI slave or controller. Thus, instead of saving it in spi_slave
structure, clean up the SPI flash driver interface. This allows
chipsets/mainboards (that require volatile operations to be grouped) to
indicate beginning and end of such grouped operations.

New user APIs are added to allow users to perform probe, read, write,
erase, volatile group begin and end operations. Callbacks defined in
spi_flash structure are expected to be used only by the SPI flash
driver. Any chipset that requires grouping of volatile operations can
select the newly added Kconfig option SPI_FLASH_HAS_VOLATILE_GROUP and
define callbacks for chipset_volatile_group_{begin,end}.

spi_claim_bus/spi_release_bus calls have been removed from the SPI flash
chip drivers which end up calling do_spi_flash_cmd since it already has
required calls for claiming and releasing SPI bus before performing a
read/write operation.

BUG=None
BRANCH=None
TEST=Compiles successfully.

Change-Id: Idfc052e82ec15b6c9fa874cee7a61bd06e923fbf
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17462
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

3 files changed, 14 insertions, 18 deletions

diff --git a/src/northbridge/amd/agesa/oem_s3.c b/src/northbridge/amd/agesa/oem_s3.c
index fcf8ada4c5..c7d23ff346 100644
--- a/src/northbridge/amd/agesa/oem_s3.c
+++ b/src/northbridge/amd/agesa/oem_s3.c
@@ -97,15 +97,13 @@ static int spi_SaveS3info(u32 pos, u32 size, u8 *buf, u32 len)
 	if (!flash)
 		return -1;
 
-	flash->spi->rw = SPI_WRITE_FLAG;
-	spi_claim_bus(flash->spi);
+	spi_flash_volatile_group_begin(flash);
 
-	flash->erase(flash, pos, size);
-	flash->write(flash, pos, sizeof(len), &len);
-	flash->write(flash, pos + sizeof(len), len, buf);
+	spi_flash_erase(flash, pos, size);
+	spi_flash_write(flash, pos, sizeof(len), &len);
+	spi_flash_write(flash, pos + sizeof(len), len, buf);
 
-	flash->spi->rw = SPI_WRITE_FLAG;
-	spi_release_bus(flash->spi);
+	spi_flash_volatile_group_end(flash);
 	return 0;
 #else
 	return -1;
diff --git a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
index 97cadcb828..d3fc53b12f 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
+++ b/src/northbridge/amd/amdmct/mct_ddr3/s3utils.c
@@ -1140,20 +1140,17 @@ int8_t save_mct_information_to_nvram(void)
 		return -1;
 	}
 
-	/* Set up SPI flash access */
-	flash->spi->rw = SPI_WRITE_FLAG;
-	spi_claim_bus(flash->spi);
+	spi_flash_volatile_group_begin(flash);
 
 	/* Erase and write data structure */
-	flash->erase(flash, s3nv_offset, CONFIG_S3_DATA_SIZE);
-	flash->write(flash, s3nv_offset, sizeof(struct amd_s3_persistent_data), persistent_data);
+	spi_flash_erase(flash, s3nv_offset, CONFIG_S3_DATA_SIZE);
+	spi_flash_write(flash, s3nv_offset,
+			sizeof(struct amd_s3_persistent_data), persistent_data);
 
 	/* Deallocate temporary data structures */
 	free(persistent_data);
 
-	/* Tear down SPI flash access */
-	flash->spi->rw = SPI_WRITE_FLAG;
-	spi_release_bus(flash->spi);
+	spi_flash_volatile_group_end(flash);
 
 	/* Allow training bypass if DIMM configuration is unchanged on next boot */
 	nvram = 1;
diff --git a/src/northbridge/intel/common/mrc_cache.c b/src/northbridge/intel/common/mrc_cache.c
index 4c3ee5d43c..a15812311b 100644
--- a/src/northbridge/intel/common/mrc_cache.c
+++ b/src/northbridge/intel/common/mrc_cache.c
@@ -212,7 +212,8 @@ static void update_mrc_cache(void *unused)
 		       "Need to erase the MRC cache region of %d bytes at %p\n",
 		       cache_size, cache_base);
 
-		flash->erase(flash, to_flash_offset(flash, cache_base), cache_size);
+		spi_flash_erase(flash, to_flash_offset(flash, cache_base),
+				cache_size);
 
 		/* we will start at the beginning again */
 		cache = cache_base;
@@ -220,8 +221,8 @@ static void update_mrc_cache(void *unused)
 	//  4. write mrc data with flash->write()
 	printk(BIOS_DEBUG, "Finally: write MRC cache update to flash at %p\n",
 	       cache);
-	ret = flash->write(flash, to_flash_offset(flash, cache),
-		     current->mrc_data_size + sizeof(*current), current);
+	ret = spi_flash_write(flash, to_flash_offset(flash, cache),
+			current->mrc_data_size + sizeof(*current), current);
 
 	if (ret)
 		printk(BIOS_WARNING, "Writing the MRC cache failed with ret %d\n",