tools/env: kernel-doc for fw_printenv, fw_getenv and fw_parse_script

there are two groups of functions:
- application ready tools: fw_setenv/fw_getenv/fw_parse_script
these are used, when creating a single binary containing multiple
tools (busybox like)
- file access like: open/read/write/close
above functions are implemented on top of these. applications
can use those to modify several variables without creating a
temporary batch script file
tested with "./scripts/kernel-doc -html -v tools/env/fw_env.h"

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Andreas Fenkart <andreas.fenkart@digitalstrom.com>

tools/env/fw_env.c

@@ -484,7 +484,7 @@ int fw_setenv(int argc, char *argv[], struct env_opts *opts)
 	valc = argc - 1;
 
 	if (env_flags_validate_env_set_params(name, valv, valc) < 0)
-		return 1;
+		return -1;
 
 	len = 0;
 	for (i = 0; i < valc; ++i) {

tools/env/fw_env.h

@@ -67,12 +67,125 @@ struct env_opts {
 
 int parse_aes_key(char *key, uint8_t *bin_key);
 
+/**
+ * fw_printenv() - print one or several environment variables
+ *
+ * @argc: number of variables names to be printed, prints all if 0
+ * @argv: array of variable names to be printed, if argc != 0
+ * @value_only: do not repeat the variable name, print the bare value,
+ *          only one variable allowed with this option, argc must be 1
+ * @opts: encryption key, configuration file, defaults are used if NULL
+ *
+ * Description:
+ *  Uses fw_env_open, fw_getenv
+ *
+ * Return:
+ *  0 on success, -1 on failure (modifies errno)
+ */
 int fw_printenv(int argc, char *argv[], int value_only, struct env_opts *opts);
-char *fw_getenv(char *name);
+
+/**
+ * fw_setenv() - adds or removes one variable to the environment
+ *
+ * @argc: number of strings in argv, argv[0] is variable name,
+ *          argc==1 means erase variable, argc > 1 means add a variable
+ * @argv: argv[0] is variable name, argv[1..argc-1] are concatenated separated
+ *           by single blank and set as the new value of the variable
+ * @opts: how to retrieve environment from flash, defaults are used if NULL
+ *
+ * Description:
+ *  Uses fw_env_open, fw_env_write, fw_env_close
+ *
+ * Return:
+ *  0 on success, -1 on failure (modifies errno)
+ *
+ * ERRORS:
+ *  EROFS - some variables ("ethaddr", "serial#") cannot be modified
+ */
 int fw_setenv(int argc, char *argv[], struct env_opts *opts);
+
+/**
+ * fw_parse_script() - adds or removes multiple variables with a batch script
+ *
+ * @fname: batch script file name
+ * @opts: encryption key, configuration file, defaults are used if NULL
+ *
+ * Description:
+ *  Uses fw_env_open, fw_env_write, fw_env_close
+ *
+ * Return:
+ *  0 success, -1 on failure (modifies errno)
+ *
+ * Script Syntax:
+ *
+ *  key [ [space]+ value]
+ *
+ *  lines starting with '#' treated as comment
+ *
+ *  A variable without value will be deleted. Any number of spaces are allowed
+ *  between key and value. The value starts with the first non-space character
+ *  and ends with newline. No comments allowed on these lines.  Spaces inside
+ *  the value are preserved verbatim.
+ *
+ * Script Example:
+ *
+ *  netdev         eth0
+ *
+ *  kernel_addr    400000
+ *
+ *  foo            spaces           are copied verbatim
+ *
+ *  # delete variable bar
+ *
+ *  bar
+ */
 int fw_parse_script(char *fname, struct env_opts *opts);
+
+
+/**
+ * fw_env_open() - read enviroment from flash into RAM cache
+ *
+ * @opts: encryption key, configuration file, defaults are used if NULL
+ *
+ * Return:
+ *  0 on success, -1 on failure (modifies errno)
+ */
 int fw_env_open(struct env_opts *opts);
+
+/**
+ * fw_getenv() - lookup variable in the RAM cache
+ *
+ * @name: variable to be searched
+ * Return:
+ *  pointer to start of value, NULL if not found
+ */
+char *fw_getenv(char *name);
+
+/**
+ * fw_env_write() - modify a variable held in the RAM cache
+ *
+ * @name: variable
+ * @value: delete variable if NULL, otherwise create or overwrite the variable
+ *
+ * This is called in sequence to update the environment in RAM without updating
+ * the copy in flash after each set
+ *
+ * Return:
+ *  0 on success, -1 on failure (modifies errno)
+ *
+ * ERRORS:
+ *  EROFS - some variables ("ethaddr", "serial#") cannot be modified
+ */
 int fw_env_write(char *name, char *value);
+
+/**
+ * fw_env_close - write the environment from RAM cache back to flash
+ *
+ * @opts: encryption key, configuration file, defaults are used if NULL
+ *
+ * Return:
+ *  0 on success, -1 on failure (modifies errno)
+ */
 int fw_env_close(struct env_opts *opts);
 
 unsigned long crc32(unsigned long, const unsigned char *, unsigned);