of: Move of_modalias() to module.c

Create a specific .c file for OF related module handling.
Move of_modalias() inside as a first step.

The helper is exposed through of.h even though it is only used by core
files because the users from device.c will soon be split into an OF-only
helper in module.c as well as a device-oriented inline helper in
of_device.h. Putting this helper in of_private.h would require to
include of_private.h from of_device.h, which is not acceptable.

Suggested-by: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230404172148.82422-10-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/of/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-y = base.o device.o platform.o property.o
+obj-y = base.o device.o module.o platform.o property.o
 obj-$(CONFIG_OF_KOBJ) += kobj.o
 obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
 obj-$(CONFIG_OF_FLATTREE) += fdt.o

drivers/of/device.c

@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -248,42 +247,6 @@ const void *of_device_get_match_data(const struct device *dev)
 }
 EXPORT_SYMBOL(of_device_get_match_data);
 
-static ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len)
-{
-	const char *compat;
-	char *c;
-	struct property *p;
-	ssize_t csize;
-	ssize_t tsize;
-
-	/* Name & Type */
-	/* %p eats all alphanum characters, so %c must be used here */
-	csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T',
-			 of_node_get_device_type(np));
-	tsize = csize;
-	len -= csize;
-	if (str)
-		str += csize;
-
-	of_property_for_each_string(np, "compatible", p, compat) {
-		csize = strlen(compat) + 1;
-		tsize += csize;
-		if (csize > len)
-			continue;
-
-		csize = snprintf(str, len, "C%s", compat);
-		for (c = str; c; ) {
-			c = strchr(c, ' ');
-			if (c)
-				*c++ = '_';
-		}
-		len -= csize;
-		str += csize;
-	}
-
-	return tsize;
-}
-
 int of_device_request_module(struct device *dev)
 {
 	char *str;

drivers/of/module.c

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Linux kernel module helpers.
+ */
+
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len)
+{
+	const char *compat;
+	char *c;
+	struct property *p;
+	ssize_t csize;
+	ssize_t tsize;
+
+	/* Name & Type */
+	/* %p eats all alphanum characters, so %c must be used here */
+	csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T',
+			 of_node_get_device_type(np));
+	tsize = csize;
+	len -= csize;
+	if (str)
+		str += csize;
+
+	of_property_for_each_string(np, "compatible", p, compat) {
+		csize = strlen(compat) + 1;
+		tsize += csize;
+		if (csize > len)
+			continue;
+
+		csize = snprintf(str, len, "C%s", compat);
+		for (c = str; c; ) {
+			c = strchr(c, ' ');
+			if (c)
+				*c++ = '_';
+		}
+		len -= csize;
+		str += csize;
+	}
+
+	return tsize;
+}

include/linux/of.h

@@ -385,6 +385,9 @@ extern int of_parse_phandle_with_args_map(const struct device_node *np,
 extern int of_count_phandle_with_args(const struct device_node *np,
 	const char *list_name, const char *cells_name);
 
+/* module functions */
+extern ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len);
+
 /* phandle iterator functions */
 extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
 				    const struct device_node *np,
@@ -742,6 +745,12 @@ static inline int of_count_phandle_with_args(const struct device_node *np,
 	return -ENOSYS;
 }
 
+static inline ssize_t of_modalias(const struct device_node *np, char *str,
+				  ssize_t len)
+{
+	return -ENODEV;
+}
+
 static inline int of_phandle_iterator_init(struct of_phandle_iterator *it,
 					   const struct device_node *np,
 					   const char *list_name,