[Skiboot] [RFC PATCH 1/2] libflash: don't use the low level interface if it doesn't exist

[Cyril Bur]

During init libflash calls low level functions without checking.

libflash states to backends that if they implement all the higher level
functions the lower level functions are optional (from libflash-priv.h):
  If all functions of the high level interface are
  implemented then the low level one is optional. A
  controller can implement some of the high level one
  in which case the missing ones will be handled by
  libflash using the low level interface.

Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 libflash/libflash.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/libflash/libflash.c b/libflash/libflash.c
index a229668..ce6a899 100644
--- a/libflash/libflash.c
+++ b/libflash/libflash.c
@@ -91,6 +91,10 @@ int fl_wren(struct spi_flash_ctrl *ct)
 	int i, rc;
 	uint8_t stat;
 
+	/* If lower level interface not implmented, just return */
+	if (!ct->cmd_wr)
+		return 0;
+
 	/* Some flashes need it to be hammered */
 	for (i = 0; i < 1000; i++) {
 		rc = ct->cmd_wr(ct, CMD_WREN, false, 0, NULL, 0);
@@ -674,6 +678,11 @@ static int flash_set_4b(struct flash_chip *c, bool enable)
 		/* Ignore the error & move on (could be wrprotect chip) */
 	}
 
+	/* Don't have low level interface, assume all is well */
+	if (!ct->cmd_wr)
+		return 0;
+
+
 	/* Ignore error in case chip is write protected */
 
 	return ct->cmd_wr(ct, enable ? CMD_EN4B : CMD_EX4B, false, 0, NULL, 0);
@@ -757,7 +766,6 @@ static int flash_configure(struct flash_chip *c)
 				return rc;
 			}
 		}
-
 		/* Set controller to 3b mode if mode switch is supported */
 		if (ct->set_4b) {
 			FL_DBG("LIBFLASH: Disabling controller 4B mode...\n");
-- 
1.9.1