env: restore old env_get_char() behaviour

With multiple environments, the 'get_char' callback for env
drivers does not really make sense any more because it is
only supported by two drivers (eeprom and nvram).

To restore single character loading for these drivers,
override 'env_get_char_spec'.

Signed-off-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>

env/eeprom.c

@@ -61,7 +61,10 @@ static int eeprom_bus_write(unsigned dev_addr, unsigned offset,
 	return rcode;
 }
 
-static int env_eeprom_get_char(int index)
+/** Call this function from overridden env_get_char_spec() if you need
+ * this functionality.
+ */
+int env_eeprom_get_char(int index)
 {
 	uchar c;
 	unsigned int off = CONFIG_ENV_OFFSET;
@@ -228,7 +231,6 @@ static int env_eeprom_save(void)
 U_BOOT_ENV_LOCATION(eeprom) = {
 	.location	= ENVL_EEPROM,
 	ENV_NAME("EEPROM")
-	.get_char	= env_eeprom_get_char,
 	.load		= env_eeprom_load,
 	.save		= env_save_ptr(env_eeprom_save),
 };

env/env.c

@@ -147,32 +147,17 @@ static struct env_driver *env_driver_lookup(enum env_operation op, int prio)
 	return drv;
 }
 
+__weak int env_get_char_spec(int index)
+{
+	return *(uchar *)(gd->env_addr + index);
+}
+
 int env_get_char(int index)
 {
-	struct env_driver *drv;
-	int prio;
-
 	if (gd->env_valid == ENV_INVALID)
 		return default_environment[index];
-
-	for (prio = 0; (drv = env_driver_lookup(ENVOP_GET_CHAR, prio)); prio++) {
-		int ret;
-
-		if (!drv->get_char)
-			continue;
-
-		if (!env_has_inited(drv->location))
-			continue;
-
-		ret = drv->get_char(index);
-		if (!ret)
-			return 0;
-
-		debug("%s: Environment %s failed to load (err=%d)\n", __func__,
-		      drv->name, ret);
-	}
-
-	return -ENODEV;
+	else
+		return env_get_char_spec(index);
 }
 
 int env_load(void)

env/nvram.c

@@ -41,7 +41,10 @@ env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
 #endif
 
 #ifdef CONFIG_SYS_NVRAM_ACCESS_ROUTINE
-static int env_nvram_get_char(int index)
+/** Call this function from overridden env_get_char_spec() if you need
+ * this functionality.
+ */
+int env_nvram_get_char(int index)
 {
 	uchar c;
 
@@ -113,9 +116,6 @@ static int env_nvram_init(void)
 U_BOOT_ENV_LOCATION(nvram) = {
 	.location	= ENVL_NVRAM,
 	ENV_NAME("NVRAM")
-#ifdef CONFIG_SYS_NVRAM_ACCESS_ROUTINE
-	.get_char	= env_nvram_get_char,
-#endif
 	.load		= env_nvram_load,
 	.save		= env_save_ptr(env_nvram_save),
 	.init		= env_nvram_init,

include/environment.h

@@ -217,17 +217,6 @@ struct env_driver {
 	const char *name;
 	enum env_location location;
 
-	/**
-	 * get_char() - Read a character from the environment
-	 *
-	 * This method is optional. If not provided, a default implementation
-	 * will read from gd->env_addr.
-	 *
-	 * @index: Index of character to read (0=first)
-	 * @return character read, or -ve on error
-	 */
-	int (*get_char)(int index);
-
 	/**
 	 * load() - Load the environment from storage
 	 *