diff --git a/Makefile b/Makefile
index 78090c6..5f803f9 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ CFLAGS := -Wall -g -O2
 LDFLAGS := -lqrtr
 
 SRCS := pd-mapper.c \
+        json.c \
 	servreg_loc.c
 
 OBJS := $(SRCS:.c=.o)
diff --git a/json.c b/json.c
new file mode 100644
index 0000000..930fea4
--- /dev/null
+++ b/json.c
@@ -0,0 +1,451 @@
+/*
+ * Copyright (c) 2018-2019, Linaro Ltd.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <sys/stat.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "json.h"
+
+static const char *input_buf;
+static int input_pos;
+static int input_len;
+
+static int json_parse_array(struct json_value *array);
+static int json_parse_object(struct json_value *object);
+static int json_parse_property(struct json_value *value);
+
+static int input(void)
+{
+	if (input_pos >= input_len)
+		return 0;
+
+	return input_buf[input_pos++];
+}
+
+static void unput(void)
+{
+	input_pos--;
+}
+
+static void json_skip_whitespace(void)
+{
+	int ch;
+
+	while ((ch = input()) && isspace(ch))
+		;
+	unput();
+}
+
+static int json_parse_string(struct json_value *value)
+{
+	char buf[128];
+	char *b = buf;
+	int ch;
+
+	ch = input();
+	if (ch != '"') {
+		unput();
+		return 0;
+	}
+
+	while ((ch = input()) && ch != '"')
+		*b++ = ch;
+	*b = '\0';
+
+	if (!ch)
+		return -1;
+
+	value->type = JSON_TYPE_STRING;
+	value->u.string = strdup(buf);
+
+	return 1;
+}
+
+static int json_parse_number(struct json_value *value)
+{
+	char buf[20];
+	char *b = buf;
+	int ch;
+
+	while ((ch = input()) && isdigit(ch) && b - buf < sizeof(buf) - 1)
+		*b++ = ch;
+	*b = '\0';
+	unput();
+
+	if (b == buf)
+		return 0;
+
+	value->type = JSON_TYPE_NUMBER;
+	value->u.number = strtod(buf, NULL);
+
+	return 1;
+}
+
+static int json_parse_keyword(struct json_value *value)
+{
+	const char *match;
+	const char *m;
+	int ch;
+
+	ch = input();
+	switch (ch) {
+	case 't':
+		match = "true";
+		value->type = JSON_TYPE_TRUE;
+		break;
+	case 'f':
+		match = "false";
+		value->type = JSON_TYPE_FALSE;
+		break;
+	case 'n':
+		match = "null";
+		value->type = JSON_TYPE_NULL;
+		break;
+	default:
+		unput();
+		return 0;
+	}
+
+	m = match;
+	while (*m && *m++ == ch)
+		ch = input();
+	unput();
+
+	return *m == '\0' ? 1 : -1;
+}
+
+static int json_parse_value(struct json_value *value)
+{
+	int ret;
+
+	json_skip_whitespace();
+
+	ret = json_parse_object(value);
+	if (ret)
+		goto out;
+
+	ret = json_parse_array(value);
+	if (ret)
+		goto out;
+
+	ret = json_parse_string(value);
+	if (ret)
+		goto out;
+
+	ret = json_parse_number(value);
+	if (ret)
+		goto out;
+
+	ret = json_parse_keyword(value);
+	if (ret)
+		goto out;
+
+	fprintf(stderr, "unable to match a value\n");
+	return -1;
+
+out:
+	json_skip_whitespace();
+	return ret;
+}
+
+static int json_parse_array(struct json_value *array)
+{
+	struct json_value *value;
+	struct json_value *last = NULL;
+	int ret;
+	int ch;
+
+	ch = input();
+	if (ch != '[') {
+		unput();
+		return 0;
+	}
+
+	array->type = JSON_TYPE_ARRAY;
+	do {
+		value = calloc(1, sizeof(*value));
+		if (!value)
+			return -1;
+
+		ret = json_parse_value(value);
+		if (ret <= 0) {
+			free(value);
+			return -1;
+		}
+
+		if (!array->u.value)
+			array->u.value = value;
+		if (last)
+			last->next = value;
+		last = value;
+
+		ch = input();
+		if (ch == ']') {
+			return 1;
+		}
+
+	} while (ch == ',');
+
+	fprintf(stderr, "expected ',' got '%c'\n", ch);
+
+	return -1;
+}
+
+static int json_parse_object(struct json_value *object)
+{
+	struct json_value *value;
+	struct json_value *last = NULL;
+	int ret;
+	int ch;
+
+	ch = input();
+	if (ch != '{') {
+		unput();
+		return 0;
+	}
+
+	object->type = JSON_TYPE_OBJECT;
+
+	do {
+		value = calloc(1, sizeof(*value));
+		if (!value)
+			return -1;
+
+		ret = json_parse_property(value);
+		if (ret <= 0) {
+			free(value);
+			return -1;
+		}
+
+		if (!object->u.value)
+			object->u.value = value;
+		if (last)
+			last->next = value;
+		last = value;
+
+		ch = input();
+		if (ch == '}') {
+			return 1;
+		}
+	} while (ch == ',');
+
+	return -1;
+}
+
+static int json_parse_property(struct json_value *value)
+{
+	struct json_value key;
+	int ret;
+	int ch;
+
+	json_skip_whitespace();
+
+	ret = json_parse_string(&key);
+	if (ret <= 0)
+		return -1;
+
+	value->key = key.u.string;
+
+	json_skip_whitespace();
+
+	ch = input();
+	if (ch != ':')
+		return -1;
+
+	ret = json_parse_value(value);
+	if (ret <= 0)
+		return -1;
+
+	return 1;
+}
+
+struct json_value *json_parse(const char *json)
+{
+	struct json_value *root;
+	int ret;
+
+	input_buf = json;
+	input_pos = 0;
+	input_len = strlen(input_buf);
+
+	root = calloc(1, sizeof(*root));
+	if (!root)
+		return NULL;
+
+	ret = json_parse_value(root);
+	if (ret != 1) {
+		free(root);
+		return NULL;
+	}
+
+	return root;
+}
+
+struct json_value *json_parse_file(const char *file)
+{
+	struct json_value *root;
+	struct stat sb;
+	int ret;
+	int fd;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "failed to open %s: %s\n", file, strerror(errno));
+		return NULL;
+	}
+
+	ret = fstat(fd, &sb);
+	if (ret < 0)
+		return NULL;
+
+	input_pos = 0;
+	input_len = sb.st_size;
+	input_buf = malloc(sb.st_size);
+
+	ret = read(fd, (char *)input_buf, input_len);
+
+	close(fd);
+
+	if (ret != input_len) {
+		fprintf(stderr, "failed to read %d bytes form %s\n", input_len, file);
+		return NULL;
+	}
+
+	root = calloc(1, sizeof(*root));
+	if (!root)
+		return NULL;
+
+	ret = json_parse_value(root);
+	if (ret != 1) {
+		free(root);
+		return NULL;
+	}
+
+	return root;
+}
+
+struct json_value *json_get_child(struct json_value *object, const char *key)
+{
+	struct json_value *it;
+
+	if(object->type != JSON_TYPE_OBJECT)
+		return NULL;
+
+	for (it = object->u.value; it; it = it->next) {
+		if (!strcmp(it->key, key))
+			return it;
+	}
+
+	return NULL;
+}
+
+int json_count_children(struct json_value *array)
+{
+	struct json_value *it;
+	int count = 0;
+
+	if (!array || array->type != JSON_TYPE_ARRAY)
+		return -1;
+
+	for (it = array->u.value; it; it = it->next)
+		count++;
+
+	return count;
+}
+
+int json_get_number(struct json_value *object, const char *key, double *number)
+{
+	struct json_value *it;
+
+	if (!object || object->type != JSON_TYPE_OBJECT)
+		return -1;
+
+	for (it = object->u.value; it; it = it->next) {
+		if (!strcmp(it->key, key)) {
+			if (it->type != JSON_TYPE_NUMBER)
+				return -1;
+
+			*number = it->u.number;
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+const char *json_get_string(struct json_value *object, const char *key)
+{
+	struct json_value *it;
+
+	if (!object || object->type != JSON_TYPE_OBJECT)
+		return NULL;
+
+	for (it = object->u.value; it; it = it->next) {
+		if (!strcmp(it->key, key)) {
+			if (it->type != JSON_TYPE_STRING)
+				return NULL;
+
+			return it->u.string;
+		}
+	}
+
+	return NULL;
+}
+
+void json_free(struct json_value *value)
+{
+	struct json_value *next;
+	struct json_value *it;
+
+	free((char *)value->key);
+
+	switch (value->type) {
+	case JSON_TYPE_OBJECT:
+	case JSON_TYPE_ARRAY:
+		it = value->u.value;
+		while (it) {
+			next = it->next;
+			json_free(it);
+			it = next;
+		}
+		break;
+	case JSON_TYPE_STRING:
+		free((char *)value->u.string);
+		break;
+	}
+
+	free(value);
+}
diff --git a/json.h b/json.h
new file mode 100644
index 0000000..91790a0
--- /dev/null
+++ b/json.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2019, Linaro Ltd.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef __JSON_H__
+#define __JSON_H__
+
+
+enum {
+	JSON_TYPE_UNKNOWN,
+	JSON_TYPE_TRUE,
+	JSON_TYPE_FALSE,
+	JSON_TYPE_NULL,
+	JSON_TYPE_NUMBER,
+	JSON_TYPE_STRING,
+	JSON_TYPE_ARRAY,
+	JSON_TYPE_OBJECT,
+};
+
+struct json_value {
+	const char *key;
+
+	int type;
+	union {
+		double number;
+		const char *string;
+		struct json_value *value;
+	} u;
+
+	struct json_value *next;
+};
+
+struct json_value *json_parse(const char *json);
+struct json_value *json_parse_file(const char *file);
+int json_count_children(struct json_value *array);
+struct json_value *json_get_child(struct json_value *object, const char *key);
+int json_get_number(struct json_value *object, const char *key, double *number);
+const char *json_get_string(struct json_value *object, const char *key);
+void json_free(struct json_value *value);
+
+#endif