mmi_info: export API for dynamically match mmi device

After flashing GKI, https://gerrit.mot.com/#/c/1439246/ is not available.
Export API to match "mmi,status" rules, the other modules can use this
API to check if driver is available at the begining of probe() function.

Change-Id: I58413e071e32b82037c72c688a7bbbadce28007c
Reviewed-on: https://gerrit.mot.com/1772580
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Konstantin Makariev <kmakariev@motorola.com>
Submit-Approved: Jira Key

drivers/mmi_info/mmi_info_main.c

@@ -16,11 +16,83 @@
 #include <linux/of_platform.h>
 #include <linux/ctype.h>
 #include <linux/slab.h>
+#include <linux/mmi_device.h>
 #include "mmi_info.h"
 
 struct mmi_chosen_info mmi_chosen_data;
 static char *bootargs_str;
 
+/**
+ *  mmi_device_is_available - check if a device is available for use
+ *
+ *  @device: Node to check for availability, with locks already held
+ *
+ *  Returns true if the status property
+ *  -- is absent,
+ *  -- refers to another property using string list as following
+ *     mmi,status = <path>, <okay property>, [<contains>,] <value1>[, <value2>...];
+ *     and at least one <value> in the list of values matches
+ *     value of /<path>/<okay property>.
+ *     Partial matches accepted when "contains" provided.
+ *  false otherwise
+ */
+bool mmi_device_is_available(struct device_node *np)
+{
+	bool found;
+	int len, operation;
+	const char *path, *mmi_dts;
+	const char *mmi_dts_val, *val;
+	struct property *prop;
+	struct device_node *mmi_np;
+
+	if (np == NULL)
+		return true;
+
+	prop = of_find_property(np, "mmi,status", &len);
+	if (prop == NULL || len < 0) {
+		return true;
+	}
+	path = prop->value;
+
+	mmi_np = of_find_node_by_path(path);
+	if (mmi_np == NULL)
+		return false;
+
+	mmi_dts = of_prop_next_string(prop, path);
+	if (mmi_dts == NULL)
+		return false;
+
+	mmi_dts_val = of_get_property(mmi_np, mmi_dts, &len);
+	if (mmi_dts_val == NULL || len <= 0)
+		return false;
+
+	val = mmi_dts;
+	operation = 0;
+	found = false;
+	while ((val = of_prop_next_string(prop, val))) {
+		if (val == NULL)
+			return false;
+
+		if (!operation) {
+			operation++;
+			if (!strcmp(val, "contains")) {
+				operation++;
+				continue;
+			}
+		}
+		if (operation == 1) {
+			if (!strcmp(val, mmi_dts_val))
+				found = true;
+		} else if (strstr(mmi_dts_val, val)) {
+			found = true;
+		}
+		if (found)
+			return true;
+	}
+	return false;
+}
+EXPORT_SYMBOL(mmi_device_is_available);
+
 int mmi_get_bootarg(char *key, char **value)
 {
 	const char *bootargs_tmp = NULL;

include/linux/mmi_device.h

@@ -0,0 +1,18 @@
+/* Copyright (c) 2020-2021, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __MMI_DEVICE_H_INCLUDED
+#define __MMI_DEVICE_H_INCLUDED
+
+bool mmi_device_is_available(struct device_node *np);
+
+#endif		/* __MMI_DEVICE_H_INCLUDED */