Add getenv_ulong() to read an integer from an environment variable

This is not an uncommon operation in U-Boot, so let's put it in a common
function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>

common/cmd_nvedit.c

@@ -540,6 +540,26 @@ int getenv_f(const char *name, char *buf, unsigned len)
 	return -1;
 }
 
+/**
+ * Decode the integer value of an environment variable and return it.
+ *
+ * @param name		Name of environemnt variable
+ * @param base		Number base to use (normally 10, or 16 for hex)
+ * @param default_val	Default value to return if the variable is not
+ *			found
+ * @return the decoded value, or default_val if not found
+ */
+ulong getenv_ulong(const char *name, int base, ulong default_val)
+{
+	/*
+	 * We can use getenv() here, even before relocation, since the
+	 * environment variable value is an integer and thus short.
+	 */
+	const char *str = getenv(name);
+
+	return str ? simple_strtoul(str, NULL, base) : default_val;
+}
+
 #if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
 
 int do_env_save(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])

include/common.h

@@ -297,6 +297,7 @@ void	env_relocate (void);
 int	envmatch     (uchar *, int);
 char	*getenv	     (const char *);
 int	getenv_f     (const char *name, char *buf, unsigned len);
+ulong getenv_ulong(const char *name, int base, ulong default_val);
 int	saveenv	     (void);
 #ifdef CONFIG_PPC		/* ARM version to be fixed! */
 int inline setenv    (const char *, const char *);