[RFC] of: base: add support to get machine model name

diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
index b3347d32349f..846f40008752 100644
--- a/arch/arm/mach-imx/cpu.c
+++ b/arch/arm/mach-imx/cpu.c
@@ -85,9 +85,7 @@  struct device * __init imx_soc_device_init(void)

 	soc_dev_attr->family = "Freescale i.MX";

-	root = of_find_node_by_path("/");
-	ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
-	of_node_put(root);
+	ret = of_machine_get_model_name(&soc_dev_attr->machine);
 	if (ret)
 		goto free_soc;

diff --git a/arch/arm/mach-mxs/mach-mxs.c b/arch/arm/mach-mxs/mach-mxs.c
index e4f21086b42b..ed9af3a894f0 100644
--- a/arch/arm/mach-mxs/mach-mxs.c
+++ b/arch/arm/mach-mxs/mach-mxs.c
@@ -391,8 +391,7 @@  static void __init mxs_machine_init(void)
 	if (!soc_dev_attr)
 		return;

-	root = of_find_node_by_path("/");
-	ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
+	ret = of_machine_get_model_name(&soc_dev_attr->machine);
 	if (ret)
 		return;

diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index 9a2db1c013d9..2e2b1b5befa4 100644
--- a/arch/mips/cavium-octeon/setup.c
+++ b/arch/mips/cavium-octeon/setup.c
@@ -498,16 +498,8 @@  static void __init init_octeon_system_type(void)
 	char const *board_type;

 	board_type = cvmx_board_type_to_string(octeon_bootinfo->board_type);
-	if (board_type == NULL) {
-		struct device_node *root;
-		int ret;
-
-		root = of_find_node_by_path("/");
-		ret = of_property_read_string(root, "model", &board_type);
-		of_node_put(root);
-		if (ret)
-			board_type = "Unsupported Board";
-	}
+	if (!board_type && of_machine_get_model_name(&board_type))
+		board_type = "Unsupported Board";

 	snprintf(octeon_system_type, sizeof(octeon_system_type), "%s (%s)",
 		 board_type, octeon_model_get_string(read_c0_prid()));
diff --git a/arch/mips/generic/proc.c b/arch/mips/generic/proc.c
index 42b33250a4a2..f7fc067bf908 100644
--- a/arch/mips/generic/proc.c
+++ b/arch/mips/generic/proc.c
@@ -10,20 +10,11 @@ 

 #include <linux/of.h>

-#include <asm/bootinfo.h>
-
 const char *get_system_type(void)
 {
 	const char *str;
-	int err;
-
-	err = of_property_read_string(of_root, "model", &str);
-	if (!err)
-		return str;
-
-	err = of_property_read_string_index(of_root, "compatible", 0, &str);
-	if (!err)
-		return str;

-	return "Unknown";
+	if (of_machine_get_model_name(&str))
+		return "Unknown";
+	return str;
 }
diff --git a/arch/sh/boards/of-generic.c b/arch/sh/boards/of-generic.c
index 1fb6d5714bae..938a14499298 100644
--- a/arch/sh/boards/of-generic.c
+++ b/arch/sh/boards/of-generic.c
@@ -135,11 +135,7 @@  static void __init sh_of_setup(char **cmdline_p)
 	board_time_init = sh_of_time_init;

 	sh_mv.mv_name = "Unknown SH model";
-	root = of_find_node_by_path("/");
-	if (root) {
-		of_property_read_string(root, "model", &sh_mv.mv_name);
-		of_node_put(root);
-	}
+	of_machine_get_model_name(&sh_mv.mv_name);

 	sh_of_smp_probe();
 }
diff --git a/drivers/of/base.c b/drivers/of/base.c
index a0bccb54a9bd..752cb8eefd6e 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -546,6 +546,40 @@  int of_machine_is_compatible(const char *compat)
 EXPORT_SYMBOL(of_machine_is_compatible);

 /**
+ * of_machine_get_model_name - Find and read the model name or the compatible
+ *		value for the machine.
+ * @model:	pointer to null terminated return string, modified only if
+ *		return value is 0.
+ *
+ * Returns a string containing either the model name or the compatible value
+ * of the machine if found, else return error.
+ *
+ * Search for a machine model name or the compatible if model name is missing
+ * in a device tree node and retrieve a null terminated string value (pointer
+ * to data, not a copy). Returns 0 on success, -EINVAL if root of the device
+ * tree is not found and other error returned by of_property_read_string on
+ * failure.
+ */
+int of_machine_get_model_name(const char **model)
+{
+	int error;
+	struct device_node *root;
+
+	root = of_find_node_by_path("/");
+	if (!root)
+		return -EINVAL;
+
+	error = of_property_read_string(root, "model", model);
+	if (error)
+		error = of_property_read_string_index(root, "compatible",
+						      0, model);
+	of_node_put(root);
+
+	return error;
+}
+EXPORT_SYMBOL(of_machine_get_model_name);
+
+/**
  *  __of_device_is_available - check if a device is available for use
  *
  *  @device: Node to check for availability, with locks already held
diff --git a/drivers/soc/fsl/guts.c b/drivers/soc/fsl/guts.c
index 0ac88263c2d7..94aef0465451 100644
--- a/drivers/soc/fsl/guts.c
+++ b/drivers/soc/fsl/guts.c
@@ -152,8 +152,7 @@  static int fsl_guts_probe(struct platform_device *pdev)
 		return PTR_ERR(guts->regs);

 	/* Register soc device */
-	machine = of_flat_dt_get_machine_name();
-	if (machine)
+	if (!of_machine_get_model_name(&machine))
 		soc_dev_attr.machine = devm_kstrdup(dev, machine, GFP_KERNEL);

 	svr = fsl_guts_get_svr();
diff --git a/drivers/soc/renesas/renesas-soc.c b/drivers/soc/renesas/renesas-soc.c
index 330960312296..d9a119073de5 100644
--- a/drivers/soc/renesas/renesas-soc.c
+++ b/drivers/soc/renesas/renesas-soc.c
@@ -228,9 +228,7 @@  static int __init renesas_soc_init(void)
 	if (!soc_dev_attr)
 		return -ENOMEM;

-	np = of_find_node_by_path("/");
-	of_property_read_string(np, "model", &soc_dev_attr->machine);
-	of_node_put(np);
+	of_machine_get_model_name(&soc_dev_attr->machine);

 	soc_dev_attr->family = kstrdup_const(family->name, GFP_KERNEL);
 	soc_dev_attr->soc_id = kstrdup_const(strchr(match->compatible, ',') + 1,
diff --git a/include/linux/of.h b/include/linux/of.h
index d72f01009297..13fc66531f1b 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -367,6 +367,7 @@  extern int of_alias_get_id(struct device_node *np, const char *stem);
 extern int of_alias_get_highest_id(const char *stem);

 extern int of_machine_is_compatible(const char *compat);
+extern int of_machine_get_model_name(const char **model);

 extern int of_add_property(struct device_node *np, struct property *prop);
 extern int of_remove_property(struct device_node *np, struct property *prop);
@@ -788,6 +789,11 @@  static inline int of_machine_is_compatible(const char *compat)
 	return 0;
 }

+static inline int of_machine_get_model_name(const char **model)
+{
+	return -EINVAL;
+}
+
 static inline bool of_console_check(const struct device_node *dn, const char *name, int index)
 {
 	return false;