[PATCH 1/2][OF] Add of_device_is_disabled function

[Josh Boyer <jwboyer@linux.vnet.ibm.com>]

IEEE 1275 defined a standard "status" property to indicate the operational
status of a device.  The property has four possible values: okay, disabled,
fail, fail-xxx.  The absence of this property means the operational status
of the device is unknown or okay.

This adds a function called of_device_is_disabled that checks to see if a
node has the status property set to "disabled".  This can be quite useful
for devices that may be present but disabled due to pin sharing, etc.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

---
 drivers/of/base.c  |   18 ++++++++++++++++++
 include/linux/of.h |    1 +
 2 files changed, 19 insertions(+)

--- linux-2.6.orig/drivers/of/base.c
+++ linux-2.6/drivers/of/base.c
@@ -117,6 +117,24 @@ int of_device_is_compatible(const struct
 EXPORT_SYMBOL(of_device_is_compatible);
 
 /**
+ *  of_device_is_disabled - Check if a device's status is disabled
+ *  @device: device node to check
+ *
+ *  Returns true or false depending on the value of the staus property
+ */
+int of_device_is_disabled(const struct device_node *device)
+{
+	const char *status;
+
+	status = of_get_property(device, "status", NULL);
+	if (status == NULL)
+		return 0;
+
+	return !(strcmp(status, "disabled"));
+}
+EXPORT_SYMBOL(of_device_is_disabled);
+
+/**
  *	of_get_parent - Get a node's parent if any
  *	@node:	Node to get parent
  *
--- linux-2.6.orig/include/linux/of.h
+++ linux-2.6/include/linux/of.h
@@ -62,6 +62,7 @@ extern struct property *of_find_property
 					 int *lenp);
 extern int of_device_is_compatible(const struct device_node *device,
 				   const char *);
+extern int of_device_is_disabled(const struct device_node *device);
 extern const void *of_get_property(const struct device_node *node,
 				const char *name,
 				int *lenp);