spi: Move 16MiB partitioning up into spi_chip_read()

We enforced a 16MiB limit in spi_read_chunked() for multi-die flash
chips that can't be fully read at once. The same limit can be useful
for dediprog programmers. So move it into a more generic place.

Change-Id: Iab1fd5b2ea550b4b3ef3e8402e0b6ca218485a51
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/33613
Reviewed-by: Ryan O'Leary
Reviewed-by: ron minnich <rminnich@gmail.com>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/spi.c b/spi.c
index a4dba1973..489baf306 100644
--- a/spi.c
+++ b/spi.c
@@ -99,7 +99,19 @@ int default_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned i
 int spi_chip_read(struct flashctx *flash, uint8_t *buf, unsigned int start,
 		  unsigned int len)
 {
-	return flash->mst->spi.read(flash, buf, start, len);
+	int ret;
+	size_t to_read;
+	for (; len; len -= to_read, buf += to_read, start += to_read) {
+		/* Do not cross 16MiB boundaries in a single transfer.
+		   This helps with
+		   o multi-die 4-byte-addressing chips,
+		   o dediprog that has a protocol limit of 32MiB-512B. */
+		to_read = min(ALIGN_DOWN(start + 16*MiB, 16*MiB) - start, len);
+		ret = flash->mst->spi.read(flash, buf, start, to_read);
+		if (ret)
+			return ret;
+	}
+	return 0;
 }
 
 /*