common/hwconfig.c

/*
 * An inteface for configuring a hardware via u-boot environment.
 *
 * Copyright (c) 2009  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 */

#include <config.h>
#include <common.h>
#include <exports.h>
#include <hwconfig.h>
#include <linux/types.h>
#include <linux/string.h>

static const char *hwconfig_parse(const char *opts, size_t maxlen,
				  const char *opt, char stopch, char eqch,
				  size_t *arglen)
{
	size_t optlen = strlen(opt);
	char *str;
	const char *start = opts;
	const char *end;

next:
	str = strstr(opts, opt);
	end = str + optlen;
	if (end - start > maxlen)
		return NULL;

	if (str && (str == opts || str[-1] == stopch) &&
			(*end == stopch || *end == eqch || *end == '\0')) {
		const char *arg_end;

		if (!arglen)
			return str;

		if (*end != eqch)
			return NULL;

		arg_end = strchr(str, stopch);
		if (!arg_end)
			*arglen = min(maxlen, strlen(str)) - optlen - 1;
		else
			*arglen = arg_end - end - 1;

		return end + 1;
	} else if (str) {
		opts = end;
		goto next;
	}
	return NULL;
}

const char *cpu_hwconfig __attribute__((weak));
const char *board_hwconfig __attribute__((weak));

static const char *__hwconfig(const char *opt, size_t *arglen)
{
	const char *env_hwconfig = getenv("hwconfig");

	if (env_hwconfig)
		return hwconfig_parse(env_hwconfig, strlen(env_hwconfig),
				      opt, ';', ':', arglen);

	if (board_hwconfig)
		return hwconfig_parse(board_hwconfig, strlen(board_hwconfig),
				      opt, ';', ':', arglen);

	if (cpu_hwconfig)
		return hwconfig_parse(cpu_hwconfig, strlen(cpu_hwconfig),
				      opt, ';', ':', arglen);

	return NULL;
}

/*
 * hwconfig - query if a particular hwconfig option is specified
 * @opt:	a string representing an option
 *
 * This call can be used to find out whether U-Boot should configure
 * a particular hardware option.
 *
 * Returns non-zero value if the hardware option can be used and thus
 * should be configured, 0 otherwise.
 *
 * This function also returns non-zero value if CONFIG_HWCONFIG is
 * undefined.
 *
 * Returning non-zero value without CONFIG_HWCONFIG has its crucial
 * purpose: the hwconfig() call should be a "transparent" interface,
 * e.g. if a board doesn't need hwconfig facility, then we assume
 * that the board file only calls things that are actually used, so
 * hwconfig() will always return true result.
 */
int hwconfig(const char *opt)
{
	return !!__hwconfig(opt, NULL);
}

/*
 * hwconfig_arg - get hwconfig option's argument
 * @opt:	a string representing an option
 * @arglen:	a pointer to an allocated size_t variable
 *
 * Unlike hwconfig() function, this function returns a pointer to the
 * start of the hwconfig arguments, if option is not found or it has
 * no specified arguments, the function returns NULL pointer.
 *
 * If CONFIG_HWCONFIG is undefined, the function returns "", and
 * arglen is set to 0.
 */
const char *hwconfig_arg(const char *opt, size_t *arglen)
{
	return __hwconfig(opt, arglen);
}

/*
 * hwconfig_arg_cmp - compare hwconfig option's argument
 * @opt:	a string representing an option
 * @arg:	a string for comparing an option's argument
 *
 * This call is similar to hwconfig_arg, but instead of returning
 * hwconfig argument and its length, it is comparing it to @arg.
 *
 * Returns non-zero value if @arg matches, 0 otherwise.
 *
 * If CONFIG_HWCONFIG is undefined, the function returns a non-zero
 * value, i.e. the argument matches.
 */
int hwconfig_arg_cmp(const char *opt, const char *arg)
{
	const char *argstr;
	size_t arglen;

	argstr = hwconfig_arg(opt, &arglen);
	if (!argstr || arglen != strlen(arg))
		return 0;

	return !strncmp(argstr, arg, arglen);
}

/*
 * hwconfig_sub - query if a particular hwconfig sub-option is specified
 * @opt:	a string representing an option
 * @subopt:	a string representing a sub-option
 *
 * This call is similar to hwconfig(), except that it takes additional
 * argument @subopt. In this example:
 * 	"dr_usb:mode=peripheral"
 * "dr_usb" is an option, "mode" is a sub-option, and "peripheral" is its
 * argument.
 */
int hwconfig_sub(const char *opt, const char *subopt)
{
	size_t arglen;
	const char *arg;

	arg = __hwconfig(opt, &arglen);
	if (!arg)
		return 0;
	return !!hwconfig_parse(arg, arglen, subopt, ',', '=', NULL);
}

/*
 * hwconfig_subarg - get hwconfig sub-option's argument
 * @opt:	a string representing an option
 * @subopt:	a string representing a sub-option
 * @subarglen:	a pointer to an allocated size_t variable
 *
 * This call is similar to hwconfig_arg(), except that it takes an additional
 * argument @subopt, and so works with sub-options.
 */
const char *hwconfig_subarg(const char *opt, const char *subopt,
			    size_t *subarglen)
{
	size_t arglen;
	const char *arg;

	arg = __hwconfig(opt, &arglen);
	if (!arg)
		return NULL;
	return hwconfig_parse(arg, arglen, subopt, ',', '=', subarglen);
}

/*
 * hwconfig_arg_cmp - compare hwconfig sub-option's argument
 * @opt:	a string representing an option
 * @subopt:	a string representing a sub-option
 * @subarg:	a string for comparing an sub-option's argument
 *
 * This call is similar to hwconfig_arg_cmp, except that it takes an additional
 * argument @subopt, and so works with sub-options.
 */
int hwconfig_subarg_cmp(const char *opt, const char *subopt, const char *subarg)
{
	const char *argstr;
	size_t arglen;

	argstr = hwconfig_subarg(opt, subopt, &arglen);
	if (!argstr || arglen != strlen(subarg))
		return 0;

	return !strncmp(argstr, subarg, arglen);
}