ti: common: board_detect: Return a valid empty string for un-initialized eeprom

Current logic for query of revision, board_name, config returns
NULL. Users of these functions do a direct strncmp to compare.
Unfortunately, as per conventions require two valid strings to compare
against and the current implementation causes a crash when compared
with NULL.

We'd still like to maintain the simplistic usage of these APIs instead
of redundant if (string) res=strncmp(fn(),"cmp",n); flowing all over
the place.

Hence, since the version, name and config is already pre-initialized
with empty string, just dont check for invalid header in the first
place and return the empty string to the caller.

Reported-by: Brad Griffis <bgriffis@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
[trini: Correct was'nt -> wasn't typo]
Signed-off-by: Tom Rini <trini@konsulko.com>

board/ti/common/board_detect.c

@@ -231,9 +231,7 @@ char * __maybe_unused board_ti_get_rev(void)
 {
 	struct ti_common_eeprom *ep = TI_EEPROM_DATA;
 
-	if (ep->header == TI_DEAD_EEPROM_MAGIC)
-		return NULL;
-
+	/* if ep->header == TI_DEAD_EEPROM_MAGIC, this is empty already */
 	return ep->version;
 }
 
@@ -241,9 +239,7 @@ char * __maybe_unused board_ti_get_config(void)
 {
 	struct ti_common_eeprom *ep = TI_EEPROM_DATA;
 
-	if (ep->header == TI_DEAD_EEPROM_MAGIC)
-		return NULL;
-
+	/* if ep->header == TI_DEAD_EEPROM_MAGIC, this is empty already */
 	return ep->config;
 }
 
@@ -251,9 +247,7 @@ char * __maybe_unused board_ti_get_name(void)
 {
 	struct ti_common_eeprom *ep = TI_EEPROM_DATA;
 
-	if (ep->header == TI_DEAD_EEPROM_MAGIC)
-		return NULL;
-
+	/* if ep->header == TI_DEAD_EEPROM_MAGIC, this is empty already */
 	return ep->name;
 }
 

board/ti/common/board_detect.h

@@ -133,7 +133,7 @@ bool board_ti_is(char *name_tag);
  *
  * NOTE: revision information is often messed up (hence the str len match) :(
  *
- * Return: false if board information does not match OR eeprom was'nt read.
+ * Return: false if board information does not match OR eeprom wasn't read.
  *	   true otherwise
  */
 bool board_ti_rev_is(char *rev_tag, int cmp_len);
@@ -141,7 +141,7 @@ bool board_ti_rev_is(char *rev_tag, int cmp_len);
 /**
  * board_ti_get_rev() - Get board revision for TI EVMs
  *
- * Return: NULL if eeprom was'nt read.
+ * Return: Empty string if eeprom wasn't read.
  *	   Board revision otherwise
  */
 char *board_ti_get_rev(void);
@@ -149,7 +149,7 @@ char *board_ti_get_rev(void);
 /**
  * board_ti_get_config() - Get board config for TI EVMs
  *
- * Return: NULL if eeprom was'nt read.
+ * Return: Empty string if eeprom wasn't read.
  *	   Board config otherwise
  */
 char *board_ti_get_config(void);
@@ -157,7 +157,7 @@ char *board_ti_get_config(void);
 /**
  * board_ti_get_name() - Get board name for TI EVMs
  *
- * Return: NULL if eeprom was'nt read.
+ * Return: Empty string if eeprom wasn't read.
  *	   Board name otherwise
  */
 char *board_ti_get_name(void);
@@ -174,14 +174,14 @@ void board_ti_get_eth_mac_addr(int index, u8 mac_addr[TI_EEPROM_HDR_ETH_ALEN]);
 /**
  * board_ti_get_emif1_size() - Get size of the DDR on emif1 for TI EVMs
  *
- * Return: NULL if eeprom was'nt read or emif1_size is not available.
+ * Return: NULL if eeprom wasn't read or emif1_size is not available.
  */
 u64 board_ti_get_emif1_size(void);
 
 /**
  * board_ti_get_emif2_size() - Get size of the DDR on emif2 for TI EVMs
  *
- * Return: NULL if eeprom was'nt read or emif2_size is not available.
+ * Return: NULL if eeprom wasn't read or emif2_size is not available.
  */
 u64 board_ti_get_emif2_size(void);