Driver core: Unified device properties interface for platform firmware

Add a uniform interface by which device drivers can request device
properties from the platform firmware by providing a property name
and the corresponding data type.  The purpose of it is to help to
write portable code that won't depend on any particular platform
firmware interface.

The following general helper functions are added:

device_property_present()
device_property_read_u8()
device_property_read_u16()
device_property_read_u32()
device_property_read_u64()
device_property_read_string()
device_property_read_u8_array()
device_property_read_u16_array()
device_property_read_u32_array()
device_property_read_u64_array()
device_property_read_string_array()

The first one allows the caller to check if the given property is
present.  The next 5 of them allow single-valued properties of
various types to be retrieved in a uniform way.  The remaining 5 are
for reading properties with multiple values (arrays of either numbers
or strings).

The interface covers both ACPI and Device Trees.

This change set includes material from Mika Westerberg and Aaron Lu.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/include/linux/property.h b/include/linux/property.h
new file mode 100644
index 000000000000..9242fb0221ba
--- /dev/null
+++ b/include/linux/property.h
@@ -0,0 +1,73 @@
+/*
+ * property.h - Unified device property interface.
+ *
+ * Copyright (C) 2014, Intel Corporation
+ * Authors: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *          Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _LINUX_PROPERTY_H_
+#define _LINUX_PROPERTY_H_
+
+#include <linux/types.h>
+
+struct device;
+
+enum dev_prop_type {
+	DEV_PROP_U8,
+	DEV_PROP_U16,
+	DEV_PROP_U32,
+	DEV_PROP_U64,
+	DEV_PROP_STRING,
+	DEV_PROP_MAX,
+};
+
+bool device_property_present(struct device *dev, const char *propname);
+int device_property_read_u8_array(struct device *dev, const char *propname,
+				  u8 *val, size_t nval);
+int device_property_read_u16_array(struct device *dev, const char *propname,
+				   u16 *val, size_t nval);
+int device_property_read_u32_array(struct device *dev, const char *propname,
+				   u32 *val, size_t nval);
+int device_property_read_u64_array(struct device *dev, const char *propname,
+				   u64 *val, size_t nval);
+int device_property_read_string_array(struct device *dev, const char *propname,
+				      const char **val, size_t nval);
+int device_property_read_string(struct device *dev, const char *propname,
+				const char **val);
+
+static inline bool device_property_read_bool(struct device *dev,
+					     const char *propname)
+{
+	return device_property_present(dev, propname);
+}
+
+static inline int device_property_read_u8(struct device *dev,
+					  const char *propname, u8 *val)
+{
+	return device_property_read_u8_array(dev, propname, val, 1);
+}
+
+static inline int device_property_read_u16(struct device *dev,
+					   const char *propname, u16 *val)
+{
+	return device_property_read_u16_array(dev, propname, val, 1);
+}
+
+static inline int device_property_read_u32(struct device *dev,
+					   const char *propname, u32 *val)
+{
+	return device_property_read_u32_array(dev, propname, val, 1);
+}
+
+static inline int device_property_read_u64(struct device *dev,
+					   const char *propname, u64 *val)
+{
+	return device_property_read_u64_array(dev, propname, val, 1);
+}
+
+#endif /* _LINUX_PROPERTY_H_ */