of: conditional status property

Add dynamic aspect to the status property. Conditional status
references another property and changes availability of the device
node based on the value of the referenced property. This allows
to manipulate the device tree at boot. For example, change availability
of certain devices based on a property set by the bootloader under
"/chosen" node. Syntax allows partial match of specified property
value by adding keyword "contains" in front of values list.

Propagation of (CR).

Change-Id: I3a69fe1b95c2e140feff54edb7048a5610a94d0c
Signed-off-by: Konstantin Makariev <hcv867@motorola.com>
Reviewed-on: https://gerrit.mot.com/1439246
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Konstantin Makariev <kmakariev@motorola.com>
Submit-Approved: Jira Key
Reviewed-on: https://gerrit.mot.com/1509716
Reviewed-by: Wang Wang <wangwang1@lenovo.com>

drivers/of/base.c

@@ -599,24 +599,71 @@ EXPORT_SYMBOL(of_machine_is_compatible);
  *
  *  @device: Node to check for availability, with locks already held
  *
- *  Returns true if the status property is absent or set to "okay" or "ok",
+ *  Returns true if the status property
+ *  -- is absent or set to "okay" or "ok",
+ *  -- refers to another property using string list as following
+ *     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
  */
 static bool __of_device_is_available(const struct device_node *device)
 {
-	const char *status;
-	int statlen;
+	struct property *pp;
+	struct device_node *np;
+	const char *val, *status;
+	const char *okay_prop_name, *okay_val;
+	bool found;
+	int len, operation;
 
 	if (!device)
 		return false;
 
-	status = __of_get_property(device, "status", &statlen);
-	if (status == NULL)
+	pp = __of_find_property(device, "status", &len);
+	if (pp == NULL)
 		return true;
 
-	if (statlen > 0) {
-		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
+	status = pp->value;
+
+	if (len > 0) {
+		if (!strncmp(status, "ok", 2))
 			return true;
+
+		if (!strncmp(status, "disable", 7))
+			return false;
+
+		np = __of_find_node_by_full_path(of_root, status);
+		if (!np)
+			return false;
+
+		okay_prop_name = of_prop_next_string(pp, status);
+		if (!okay_prop_name)
+			return false;
+
+		okay_val = __of_get_property(np, okay_prop_name, &len);
+		if (okay_val == NULL || len <= 0)
+			return false;
+
+		val = okay_prop_name;
+		operation = 0;
+		found = false;
+		while ((val = of_prop_next_string(pp, val))) {
+			if (!operation) {
+				operation++;
+				if (!strcmp(val, "contains")) {
+					operation++;
+					continue;
+				}
+			}
+			if (operation == 1) {
+				if (!strcmp(val, okay_val))
+						found = true;
+			} else if (strstr(okay_val, val))
+						found = true;
+			if (found)
+				return true;
+		}
 	}
 
 	return false;