[RFC PATCH v2 00/16] Add ACPI _DSD and unified device properties support

@@ -0,0 +1,410 @@
+ACPI device properties
+======================
+This document describes the format and interfaces of ACPI device
+properties as specified in "Device Properties UUID For _DSD" available
+here:
+
+http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
+
+1. Introduction
+---------------
+In systems that use ACPI and want to take advantage of device specific
+properties, there needs to be a standard way to return and extract
+name-value pairs for a given ACPI device.
+
+An ACPI device that wants to export its properties must implement a
+static name called _DSD that takes no arguments and returns a package of
+packages:
+
+	Name (_DSD, Package () {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+			Package () {"name1", <VALUE1>},
+			Package () {"name2", <VALUE2>}
+		}
+	})
+
+The UUID identifies contents of the following package. In case of ACPI
+device properties it is daffd814-6eba-4d8c-8a91-bc9bbf4aa301.
+
+In each returned package, the first item is the name and must be a string.
+The corresponding value can be a string, integer, reference, or package. If
+a package it may only contain strings, integers, and references.
+
+An example device where we might need properties is a device that uses
+GPIOs. In addition to the GpioIo/GpioInt resources the driver needs to
+know which GPIO is used for which purpose.
+
+To solve this we add the following ACPI device properties to the device:
+
+	Device (DEV0)
+	{
+		Name (_CRS, ResourceTemplate () {
+			GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
+				"\\_SB.PCI0.LPC", 0, ResourceConsumer) {0}
+			GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
+				"\\_SB.PCI0.LPC", 0, ResourceConsumer) {1}
+			...
+		})
+
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {"reset-gpio", {^DEV0, 0, 0, 0}},
+				Package () {"shutdown-gpio", {^DEV0, 1, 0, 0}},
+			}
+		})
+	}
+
+Now the device driver can reference the GPIOs using names instead of
+using indexes.
+
+If there is an existing Device Tree binding for a device, it is expected
+that the same bindings are used with ACPI properties, so that the driver
+dealing with the device needs only minor modifications if any.
+
+2. Formal definition of properties
+----------------------------------
+The following chapters define the currently supported properties. For
+these there exists a helper function that can be used to extract the
+property value.
+
+2.1 Integer types
+-----------------
+ACPI integers are always 64-bit. However, for drivers the full range is
+typically not needed so we provide a set of functions which convert the
+64-bit integer to a smaller Linux integer type.
+
+An integer property looks like this:
+
+	Package () {"i2c-sda-hold-time-ns", 300},
+	Package () {"clock-frequency", 400000},
+
+To read a property value, use a unified property accessor as shown
+below:
+
+	u32 val;
+	int ret;
+
+	ret = device_property_read_u32(dev, "clock-frequency", &val);
+	if (ret)
+		/* Handle error */
+
+The function returns 0 if the property is copied to 'val' or negative
+errno if something went wrong (or the property does not exist).
+
+2.2 Integer arrays
+------------------
+An integer array is a package holding only integers. Arrays can be used to
+represent different things like Linux input key codes to GPIO mappings, pin
+control settings, dma request lines, etc.
+
+An integer array looks like this:
+
+	Package () {
+		"max8952,dvs-mode-microvolt",
+		Package () {
+			1250000,
+			1200000,
+			1050000,
+			950000,
+		}
+	}
+
+The above array property can be accessed like:
+
+	u32 voltages[4];
+	int ret;
+
+	ret = device_property_read_u32_array(dev, "max8952,dvs-mode-microvolt",
+					     voltages, ARRAY_SIZE(voltages));
+	if (ret)
+		/* Handle error */
+
+
+All functions copy the resulting values cast to a requested type to the
+caller supplied array. If you pass NULL in the value pointer ('voltages' in
+this case), the function returns number of items in the array. This can be
+useful if caller does not know size of the array beforehand.
+
+2.3 Strings
+-----------
+String properties can be used to describe many things like labels for GPIO
+buttons, compability ids, etc.
+
+A string property looks like this:
+
+	Package () {"pwm-names", "backlight"},
+	Package () {"label", "Status-LED"},
+
+You can use device_property_read_string() to extract strings:
+
+	const char *val;
+	int ret;
+
+	ret = device_property_read_string(dev, "label", &val);
+	if (ret)
+		/* Handle error */
+
+Note that the function does not copy the returned string but instead the
+value is modified to point to the string property itself.
+
+The memory is owned by the associated ACPI device object and released
+when it is removed. The user need not free the associated memory.
+
+2.4 String arrays
+-----------------
+String arrays can be useful in describing a list of labels, names for
+DMA channels, etc.
+
+A string array property looks like this:
+
+	Package () {"dma-names", Package () {"tx", "rx", "rx-tx"}},
+	Package () {"clock-output-names", Package () {"pll", "pll-switched"}},
+
+And these can be read in similar way that the integer arrrays:
+
+	const char *dma_names[3];
+	int ret;
+
+	ret = device_property_read_string_array(dev, "dma-names", dma_names,
+						ARRAY_SIZE(dma_names));
+	if (ret)
+		/* Handle error */
+
+The memory management rules follow what is specified for single strings.
+Specifically the returned pointers should be treated as constant and not to
+be freed. That is done automatically when the correspondig ACPI device
+object is released.
+
+2.5 Object references
+---------------------
+An ACPI object reference is used to refer to some object in the
+namespace. For example, if a device has dependencies with some other
+object, an object reference can be used.
+
+An object reference looks like this:
+
+	Package () {"dev0", \_SB.DEV0},
+
+At the time of writing this, there is no unified device_property_* accessor
+for references so one needs to use the following ACPI helper function:
+
+	int acpi_dev_get_property_reference(struct acpi_device *adev,
+					    const char *name,
+					    const char *size_prop, int index,
+					    struct acpi_reference_args *args);
+
+The referenced ACPI device is returned in args->adev if found.
+
+In addition to simple object references it is also possible to have object
+references with arguments. These are represented in ASL as follows:
+
+	Device (\_SB.PCI0.PWM)
+	{
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {"#pwm-cells", 2}
+			}
+		})
+	}
+
+	Device (\_SB.PCI0.BL)
+	{
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {
+					"pwms",
+					Package () {
+						\_SB.PCI0.PWM, 0, 5000000,
+						\_SB.PCI0.PWM, 1, 4500000,
+					}
+				}
+			}
+		})
+	}
+
+In the above example, the referenced device declares a property that
+returns the number of expected arguments (here it is "#pwm-cells"). If
+no such property is given we assume that all the integers following the
+reference are arguments.
+
+In the above example PWM device expects 2 additional arguments. This
+will be validated by the ACPI property core.
+
+The additional arguments must be integers. Nothing else is supported.
+
+It is possible, as in the above example, to have multiple references
+with varying number of integer arguments. It is up to the referenced
+device to declare how many arguments it expects. The 'index' parameter
+selects which reference is returned.
+
+One can use acpi_dev_get_property_reference() as well to extract the
+information in additional parameters:
+
+	struct acpi_reference_args args;
+	struct acpi_device *adev = /* this will point to the BL device */
+	int ret;
+
+	/* extract the first reference */
+	acpi_dev_get_property_reference(adev, "pwms", "#pwm-cells", 0, &args);
+
+	BUG_ON(args.nargs != 2);
+	BUG_ON(args.args[0] != 0);
+	BUG_ON(args.args[1] != 5000000);
+
+	/* extract the second reference */
+	acpi_dev_get_property_reference(adev, "pwms", "#pwm-cells", 1, &args);
+
+	BUG_ON(args.nargs != 2);
+	BUG_ON(args.args[0] != 1);
+	BUG_ON(args.args[1] != 4500000);
+
+In addition to arguments, args.adev now points to the ACPI device that
+corresponds to \_SB.PCI0.PWM.
+
+It is intended that this function is not used directly but instead
+subsystems like pwm implement their ACPI support on top of this function
+in such way that it is hidden from the client drivers, such as via
+pwm_get().
+
+3. Device property hierarchies
+------------------------------
+Devices are organized in a tree within the Linux kernel. It follows that
+the configuration data would also be hierarchical. In order to reach
+equivalence with Device Tree, the ACPI mechanism must also provide some
+sort of tree-like representation. Fortunately, the ACPI namespace is
+already such a structure.
+
+For example, we could have the following device in ACPI namespace. The
+KEYS device is much like gpio_keys_polled.c in that it includes "pseudo"
+devices for each GPIO:
+
+	Device (KEYS)
+	{
+		Name (_CRS, ResourceTemplate () {
+			GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
+				"\\_SB.PCI0.LPC", 0, ResourceConsumer) {0}
+			GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
+				"\\_SB.PCI0.LPC", 0, ResourceConsumer) {1}
+			...
+		})
+
+		// "pseudo" devices declared under the parent device
+		Device (BTN0) {
+			Name (_DSD, Package () {
+				ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+				Package () {
+					Package () {"label", "minnow_btn0"}
+					Package () {"gpios", Package () {^KEYS, 0, 0, 1}}
+				}
+			})
+		}
+
+		Device (BTN1) {
+			Name (_DSD, Package () {
+				ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+				Package () {
+					Package () {"label", "minnow_btn1"}
+					Package () {"gpios", Package () {^KEYS, 1, 0, 1}}
+				}
+			})
+		}
+	}
+
+We can extract the above in gpio_keys_polled.c like:
+
+	static int gpio_keys_polled_create_button(struct fw_dev_node *fdn,
+						  void *data)
+	{
+		struct button_data *bdata = data;
+		const char *label = NULL;
+
+		/*
+		 * We need to use dev_node_ variant here to access the
+		 * firmware properties.
+		 */
+		dev_node_property_read_string(fdn, "label", &label);
+		/* and so on */
+	}
+
+	static void gpio_keys_polled_probe(struct device *dev)
+	{
+		/* Properties for the KEYS device itself */
+		device_property_read(dev, ...);
+
+		/*
+		 * Iterate over button devices and extract their
+		 * firmware configuration.
+		 */
+		ret = device_for_each_child_node(dev, gpio_keys_polled_create_button,
+						 &bdata);
+		if (ret)
+			/* Handle error */
+	}
+
+Note that you still need proper error handling which is omitted in the
+above example.
+
+4. Existing Device Tree enabled drivers
+---------------------------------------
+At the time of writing this, there are ~250 existing DT enabled drivers.
+Allocating _HID/_CID for each would not be feasible. To make sure that
+those drivers can still be used on ACPI systems, we provide an
+alternative way to get these matched.
+
+There is a special _HID "PRP0001" which means that use the DT bindings
+for matching this device to a driver. The driver needs to have
+.of_match_table filled in even when !CONFIG_OF.
+
+An example device would be leds that can be controlled via GPIOs. This
+is represented as "leds-gpio" device and looks like this in the ACPI
+namespace:
+
+	Device (LEDS)
+	{
+		Name (_DSD, Package () {
+			ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+			Package () {
+				Package () {"compatible", Package () {"gpio-leds"}},
+			}
+		})
+		...
+	}
+
+In order to get the existing drivers/leds/leds-gpio.c bound to this
+device, we take advantage of "PRP0001":
+
+	/* Following already exists in the driver */
+	static const struct of_device_id of_gpio_leds_match[] = {
+		{ .compatible = "gpio-leds", },
+		{},
+	};
+	MODULE_DEVICE_TABLE(of, of_gpio_leds_match);
+
+	/* This we add to the driver to get it probed */
+	static const struct acpi_device_id acpi_gpio_leds_match[] = {
+		{ "PRP0001" }, /* Device Tree shoehorned into ACPI */
+		{},
+	};
+	MODULE_DEVICE_TABLE(acpi, acpi_gpio_leds_match);
+
+	static struct platform_driver gpio_led_driver = {
+		.driver = {
+			/*
+			 * No of_match_ptr() here because we want this
+			 * table to be visible even when !CONFIG_OF to
+			 * match against "compatible" in _DSD.
+			 */
+			.of_match_table = of_gpio_leds_match,
+			.acpi_match_table = acpi_gpio_leds_match,
+		},
+	};
+
+Once ACPI core sees "PRP0001" and that the device has "compatible"
+property it will do the match using .of_match_table instead.
+
+It is preferred that new devices get a proper _HID allocated for them
+instead of inventing new DT "compatible" devices.

@@ -362,3 +362,189 @@ int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
 	return -EPROTO;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_get_property_reference);
+
+int acpi_dev_prop_get(struct acpi_device *adev, const char *propname,
+		      void **valptr)
+{
+	return acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
+				     (const union acpi_object **)valptr);
+}
+
+int acpi_dev_prop_read(struct acpi_device *adev, const char *propname,
+		       enum dev_prop_type proptype, void *val)
+{
+	const union acpi_object *obj;
+	int ret = -EINVAL;
+
+	if (!val)
+		return -EINVAL;
+
+	if (proptype >= DEV_PROP_U8 && proptype <= DEV_PROP_U64) {
+		ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_INTEGER, &obj);
+		if (ret)
+			return ret;
+
+		switch (proptype) {
+		case DEV_PROP_U8:
+			if (obj->integer.value > U8_MAX)
+				return -EOVERFLOW;
+			*(u8 *)val = obj->integer.value;
+			break;
+		case DEV_PROP_U16:
+			if (obj->integer.value > U16_MAX)
+				return -EOVERFLOW;
+			*(u16 *)val = obj->integer.value;
+			break;
+		case DEV_PROP_U32:
+			if (obj->integer.value > U32_MAX)
+				return -EOVERFLOW;
+			*(u32 *)val = obj->integer.value;
+			break;
+		default:
+			*(u64 *)val = obj->integer.value;
+			break;
+		}
+	} else if (proptype == DEV_PROP_STRING) {
+		ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_STRING, &obj);
+		if (ret)
+			return ret;
+
+		*(char **)val = obj->string.pointer;
+	}
+	return ret;
+}
+
+static int acpi_copy_property_array_u8(const union acpi_object *items, u8 *val,
+				       size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		if (items[i].type != ACPI_TYPE_INTEGER)
+			return -EPROTO;
+		if (items[i].integer.value > U8_MAX)
+			return -EOVERFLOW;
+
+		val[i] = items[i].integer.value;
+	}
+	return 0;
+}
+
+static int acpi_copy_property_array_u16(const union acpi_object *items,
+					u16 *val, size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		if (items[i].type != ACPI_TYPE_INTEGER)
+			return -EPROTO;
+		if (items[i].integer.value > U16_MAX)
+			return -EOVERFLOW;
+
+		val[i] = items[i].integer.value;
+	}
+	return 0;
+}
+
+static int acpi_copy_property_array_u32(const union acpi_object *items,
+					u32 *val, size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		if (items[i].type != ACPI_TYPE_INTEGER)
+			return -EPROTO;
+		if (items[i].integer.value > U32_MAX)
+			return -EOVERFLOW;
+
+		val[i] = items[i].integer.value;
+	}
+	return 0;
+}
+
+static int acpi_copy_property_array_u64(const union acpi_object *items,
+					u64 *val, size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		if (items[i].type != ACPI_TYPE_INTEGER)
+			return -EPROTO;
+
+		val[i] = items[i].integer.value;
+	}
+	return 0;
+}
+
+static int acpi_copy_property_array_string(const union acpi_object *items,
+					   char **val, size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		if (items[i].type != ACPI_TYPE_STRING)
+			return -EPROTO;
+
+		val[i] = items[i].string.pointer;
+	}
+	return 0;
+}
+
+int acpi_dev_prop_read_array(struct acpi_device *adev, const char *propname,
+			     enum dev_prop_type proptype, void *val,
+			     size_t nval)
+{
+	const union acpi_object *obj;
+	const union acpi_object *items;
+	int ret;
+
+	ret = acpi_dev_get_property_array(adev, propname, ACPI_TYPE_ANY, &obj);
+	if (ret)
+		return ret;
+
+	if (!val)
+		return obj->package.count;
+
+	if (nval > obj->package.count)
+		nval = obj->package.count;
+
+	items = obj->package.elements;
+	switch (proptype) {
+	case DEV_PROP_U8:
+		ret = acpi_copy_property_array_u8(items, (u8 *)val, nval);
+		break;
+	case DEV_PROP_U16:
+		ret = acpi_copy_property_array_u16(items, (u16 *)val, nval);
+		break;
+	case DEV_PROP_U32:
+		ret = acpi_copy_property_array_u32(items, (u32 *)val, nval);
+		break;
+	case DEV_PROP_U64:
+		ret = acpi_copy_property_array_u64(items, (u64 *)val, nval);
+		break;
+	case DEV_PROP_STRING:
+		ret = acpi_copy_property_array_string(items, (char **)val, nval);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret;
+}
+
+int acpi_for_each_child_node(struct acpi_device *adev,
+			      int (*fn)(struct fw_dev_node *fdn, void *data),
+			      void *data)
+{
+	struct acpi_device *child;
+	int ret = 0;
+
+	list_for_each_entry(child, &adev->children, node) {
+		struct fw_dev_node fdn = { .acpi_node = child, };
+
+		ret = fn(&fdn, data);
+		if (ret)
+			break;
+	}
+	return ret;
+}

@@ -4,7 +4,7 @@ obj-y			:= component.o core.o bus.o dd.o syscore.o \
 			   driver.o class.o platform.o \
 			   cpu.o firmware.o init.o map.o devres.o \
 			   attribute_container.o transport_class.o \
-			   topology.o container.o
+			   topology.o container.o property.o
 obj-$(CONFIG_DEVTMPFS)	+= devtmpfs.o
 obj-$(CONFIG_DMA_CMA) += dma-contiguous.o
 obj-y			+= power/

@@ -0,0 +1,196 @@
+/*
+ * property.c - 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.
+ */
+
+#include <linux/property.h>
+#include <linux/export.h>
+#include <linux/acpi.h>
+#include <linux/of.h>
+
+/**
+ * dev_node_get_property - return a raw property from device description
+ * @fdn: Device node to get the property from
+ * @propname: Name of the property
+ * @valptr: The raw property value is stored here
+ *
+ * Function reads property @propname from the device firmware description and
+ * stores the raw value into @valptr if found.  Otherwise returns a negative
+ * errno as specified below.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not exist.
+ */
+int dev_node_get_property(struct fw_dev_node *fdn, const char *propname,
+			  void **valptr)
+{
+	if (IS_ENABLED(CONFIG_OF) && fdn->of_node)
+		return of_dev_prop_get(fdn->of_node, propname, valptr);
+	else if (IS_ENABLED(CONFIG_ACPI) && fdn->acpi_node)
+		return acpi_dev_prop_get(fdn->acpi_node, propname, valptr);
+
+	return -ENODATA;
+}
+EXPORT_SYMBOL_GPL(dev_node_get_property);
+
+/**
+ * device_get_property - return a raw property of a device
+ * @dev: Device get the property of
+ * @propname: Name of the property
+ * @valptr: The raw property value is stored here
+ */
+int device_get_property(struct device *dev, const char *propname, void **valptr)
+{
+	struct fw_dev_node fdn = {
+		.of_node = dev->of_node,
+		.acpi_node = ACPI_COMPANION(dev),
+	};
+	return dev_node_get_property(&fdn, propname, valptr);
+}
+EXPORT_SYMBOL_GPL(device_get_property);
+
+/**
+ * dev_node_read_property - return a typed property from device description
+ * @fdn: Device node to get the property from
+ * @propname: Name of the property
+ * @proptype: Type of the property
+ * @val: The value is stored here
+ *
+ * Function reads property @propname from the device firmware description and
+ * stores the value into @val if found. The value is checked to be of type
+ * @proptype.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not exist,
+ *	   %-EPROTO if the property type does not match @proptype,
+ *	   %-EOVERFLOW if the property value is out of bounds of @proptype.
+ */
+int dev_node_read_property(struct fw_dev_node *fdn, const char *propname,
+			   enum dev_prop_type proptype, void *val)
+{
+	if (IS_ENABLED(CONFIG_OF) && fdn->of_node)
+		return of_dev_prop_read(fdn->of_node, propname, proptype, val);
+	else if (IS_ENABLED(CONFIG_ACPI) && fdn->acpi_node)
+		return acpi_dev_prop_read(fdn->acpi_node, propname, proptype, val);
+
+	return -ENODATA;
+}
+EXPORT_SYMBOL_GPL(dev_node_read_property);
+
+/**
+ * device_read_property - return a typed property of a device
+ * @dev: Device to get the property of
+ * @propname: Name of the property
+ * @proptype: Type of the property
+ * @val: The value is stored here
+ */
+int device_read_property(struct device *dev, const char *propname,
+			 enum dev_prop_type proptype, void *val)
+{
+	struct fw_dev_node fdn = {
+		.of_node = dev->of_node,
+		.acpi_node = ACPI_COMPANION(dev),
+	};
+	return dev_node_read_property(&fdn, propname, proptype, val);
+}
+EXPORT_SYMBOL_GPL(device_read_property);
+
+/**
+ * dev_node_read_property_array - return an array property from a device
+ * @fdn: Device node to get the property from
+ * @propname: Name of the property
+ * @proptype: Type of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Function reads an array of properties with @propname from the device
+ * firmware description and stores them to @val if found. All the values
+ * in the array must be of type @proptype.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not exist,
+ *	   %-EPROTO if the property type does not match @proptype,
+ *	   %-EOVERFLOW if the property value is out of bounds of @proptype.
+ */
+int dev_node_read_property_array(struct fw_dev_node *fdn, const char *propname,
+				 enum dev_prop_type proptype, void *val,
+				 size_t nval)
+{
+	if (IS_ENABLED(CONFIG_OF) && fdn->of_node)
+		return of_dev_prop_read_array(fdn->of_node, propname, proptype,
+					      val, nval);
+	else if (IS_ENABLED(CONFIG_ACPI) && fdn->acpi_node)
+		return acpi_dev_prop_read_array(fdn->acpi_node, propname,
+						proptype, val, nval);
+
+	return -ENODATA;
+}
+EXPORT_SYMBOL_GPL(dev_node_read_property_array);
+
+/**
+ * device_read_property_array - return an array property of a device
+ * @dev: Device to get the property of
+ * @propname: Name of the property
+ * @proptype: Type of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ */
+int device_read_property_array(struct device *dev, const char *propname,
+			       enum dev_prop_type proptype, void *val,
+			       size_t nval)
+{
+	struct fw_dev_node fdn = {
+		.of_node = dev->of_node,
+		.acpi_node = ACPI_COMPANION(dev),
+	};
+	return dev_node_read_property_array(&fdn, propname, proptype, val, nval);
+}
+EXPORT_SYMBOL_GPL(device_read_property_array);
+
+/**
+ * device_for_each_child_node - execute function for each child node of device
+ * @dev: Device to run the function for
+ * @fn: Function to run
+ * @data: Additional data to pass to the function
+ */
+int device_for_each_child_node(struct device *dev,
+			       int (*fn)(struct fw_dev_node *fdn, void *data),
+			       void *data)
+{
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
+		return of_for_each_child_node(dev->of_node, fn, data);
+	else if (ACPI_COMPANION(dev))
+		return acpi_for_each_child_node(ACPI_COMPANION(dev), fn, data);
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(device_for_each_child_node);
+
+static int dev_node_count(struct fw_dev_node *fdn, void *data)
+{
+	*((int *)data) += 1;
+	return 0;
+}
+
+/**
+ * device_get_child_node_count - return number of child nodes for this device
+ * @dev: Device to get the child node count from
+ */
+int device_get_child_node_count(struct device *dev)
+{
+	int count = 0;
+
+	device_for_each_child_node(dev, dev_node_count, &count);
+	return count;
+}
+EXPORT_SYMBOL_GPL(device_get_child_node_count);

@@ -1241,6 +1241,39 @@ int of_property_read_u64(const struct device_node *np, const char *propname,
 EXPORT_SYMBOL_GPL(of_property_read_u64);
 
 /**
+ * of_property_read_u64_array - Find and read an array of 64 bit integers
+ * from a property.
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @out_values:	pointer to return value, modified only if return value is 0.
+ * @sz:		number of array elements to read
+ *
+ * Search for a property in a device node and read 64-bit value(s) from
+ * it. Returns 0 on success, -EINVAL if the property does not exist,
+ * -ENODATA if property does not have a value, and -EOVERFLOW if the
+ * property data isn't large enough.
+ *
+ * The out_values is modified only if a valid u64 value can be decoded.
+ */
+int of_property_read_u64_array(const struct device_node *np,
+			       const char *propname, u64 *out_values,
+			       size_t sz)
+{
+	const __be32 *val = of_find_property_value_of_size(np, propname,
+						(sz * sizeof(*out_values)));
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	while (sz--) {
+		*out_values++ = of_read_number(val, 2);
+		val += 2;
+	};
+	return 0;
+}
+
+/**
  * of_property_read_string - Find and read a string from a property
  * @np:		device node from which the property value is to be read.
  * @propname:	name of the property to be searched.

@@ -1388,6 +1421,49 @@ int of_property_count_strings(struct device_node *np, const char *propname)
 }
 EXPORT_SYMBOL_GPL(of_property_count_strings);
 
+/**
+ * of_property_read_string_array - Find and read an array of strings
+ * from a multiple strings property.
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @out_string:	pointer to null terminated return string, modified only if
+ *		return value is 0.
+ * @sz:		number of array elements to read
+ *
+ * Search for a property in a device tree node and retrieve a list of
+ * terminated string value (pointer to data, not a copy) in that property.
+ * Returns 0 on success, -EINVAL if the property does not exist, -ENODATA if
+ * property does not have a value, and -EOVERFLOW if the string is not
+ * null-terminated within the length of the property data.
+ *
+ * The out_string pointer is modified only if a valid string can be decoded.
+ */
+int of_property_read_string_array(struct device_node *np, const char *propname,
+				  char **output, size_t sz)
+{
+	struct property *prop = of_find_property(np, propname, NULL);
+	int i = 0;
+	size_t l = 0, total = 0;
+	char *p;
+
+	if (!prop)
+		return -EINVAL;
+
+	if (!prop->value)
+		return -ENODATA;
+
+	if (strnlen(prop->value, prop->length) >= prop->length)
+		return -EOVERFLOW;
+
+	p = prop->value;
+
+	for (i = 0; total < prop->length; total += l, p += l) {
+		output[i++] = p;
+		l = strlen(p) + 1;
+	}
+	return 0;
+}
+
 void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
 {
 	int i;

@@ -2171,3 +2247,115 @@ struct device_node *of_graph_get_remote_port(const struct device_node *node)
 	return of_get_next_parent(np);
 }
 EXPORT_SYMBOL(of_graph_get_remote_port);
+
+int of_dev_prop_get(struct device_node *dn, const char *propname, void **valptr)
+{
+	struct property *pp = of_find_property(dn, propname, NULL);
+
+	if (!pp)
+		return -ENODATA;
+
+	if (valptr)
+		*valptr = pp->value;
+	return 0;
+}
+
+int of_dev_prop_read(struct device_node *dn, const char *propname,
+		     enum dev_prop_type proptype, void *val)
+{
+	void *value;
+	int ret = of_dev_prop_get(dn, propname, &value);
+
+	if (ret)
+		return ret;
+
+	if (proptype >= DEV_PROP_U8 && proptype <= DEV_PROP_U64) {
+		switch (proptype) {
+		case DEV_PROP_U8: {
+			*(u8 *)val = *(u8 *)value;
+			break;
+		}
+		case DEV_PROP_U16:
+			*(u16 *)val = *(u16 *)value;
+			break;
+		case DEV_PROP_U32:
+			*(u32 *)val = *(u32 *)value;
+			break;
+		default:
+			*(u64 *)val = *(u64 *)value;
+			break;
+		}
+	} else if (proptype == DEV_PROP_STRING) {
+		*(char **)val = value;
+	}
+	return ret;
+
+}
+
+int of_dev_prop_read_array(struct device_node *dn, const char *propname,
+			   enum dev_prop_type proptype, void *val, size_t nval)
+{
+	int ret, elem_size;
+
+	if (!val) {
+		switch (proptype) {
+		case DEV_PROP_U8:
+			elem_size = sizeof(u8);
+			break;
+		case DEV_PROP_U16:
+			elem_size = sizeof(u16);
+			break;
+		case DEV_PROP_U32:
+			elem_size = sizeof(u32);
+			break;
+		case DEV_PROP_U64:
+			elem_size = sizeof(u64);
+			break;
+		case DEV_PROP_STRING:
+			return of_property_count_strings(dn, propname);
+		default:
+			return -EINVAL;
+		}
+		return of_property_count_elems_of_size(dn, propname, elem_size);
+	}
+
+	switch (proptype) {
+	case DEV_PROP_U8:
+		ret = of_property_read_u8_array(dn, propname, (u8 *)val, nval);
+		break;
+	case DEV_PROP_U16:
+		ret = of_property_read_u16_array(dn, propname, (u16 *)val, nval);
+		break;
+	case DEV_PROP_U32:
+		ret = of_property_read_u32_array(dn, propname, (u32 *)val, nval);
+		break;
+	case DEV_PROP_U64:
+		ret = of_property_read_u64_array(dn, propname, (u64 *)val, nval);
+		break;
+	case DEV_PROP_STRING:
+		ret = of_property_read_string_array(dn, propname,
+						    (char **)val, nval);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret;
+}
+
+int of_for_each_child_node(struct device_node *dn,
+			    int (*fn)(struct fw_dev_node *fdn, void *data),
+			    void *data)
+{
+	struct device_node *child;
+	int ret = 0;
+
+	for_each_child_of_node(dn, child) {
+		struct fw_dev_node fdn = { .of_node = child, };
+
+		ret = fn(&fdn, data);
+		if (ret)
+			break;
+	}
+	return ret;
+}

@@ -28,6 +28,7 @@
 #include <linux/errno.h>
 #include <linux/ioport.h>	/* for struct resource */
 #include <linux/device.h>
+#include <linux/property.h>
 
 #ifndef _LINUX
 #define _LINUX

@@ -678,6 +679,17 @@ int acpi_dev_get_property_array(struct acpi_device *adev, const char *name,
 int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
 				    const char *cells_name, size_t index,
 				    struct acpi_reference_args *args);
+
+int acpi_dev_prop_get(struct acpi_device *adev, const char *propname,
+		      void **valptr);
+int acpi_dev_prop_read(struct acpi_device *adev, const char *propname,
+		       enum dev_prop_type proptype, void *val);
+int acpi_dev_prop_read_array(struct acpi_device *adev, const char *propname,
+			     enum dev_prop_type proptype, void *val,
+			     size_t nval);
+int acpi_for_each_child_node(struct acpi_device *adev,
+			      int (*fn)(struct fw_dev_node *fdn, void *data),
+			      void *data);
 #else
 static inline int acpi_dev_get_property(struct acpi_device *adev,
 					const char *name, acpi_object_type type,

@@ -698,6 +710,36 @@ static inline int acpi_dev_get_property_reference(struct acpi_device *adev,
 {
 	return -ENXIO;
 }
+
+static inline int acpi_dev_prop_get(struct acpi_device *adev,
+				    const char *propname,
+				    void **valptr)
+{
+	return -ENXIO;
+}
+
+static inline int acpi_dev_prop_read(struct acpi_device *adev,
+				     const char *propname,
+				     enum dev_prop_type proptype, void *val)
+{
+	return -ENXIO;
+}
+
+static inline int acpi_dev_prop_read_array(struct acpi_device *adev,
+					   const char *propname,
+					   enum dev_prop_type proptype,
+					   void *val, size_t nval)
+{
+	return -ENXIO;
+}
+
+static inline int acpi_for_each_child_node(struct acpi_device *adev,
+				int (*fn)(struct fw_dev_node *fdn, void *data),
+				void *data)
+{
+	return -ENXIO;
+}
+
 #endif
 
 #endif	/*_LINUX_ACPI_H*/

@@ -23,6 +23,7 @@
 #include <linux/spinlock.h>
 #include <linux/topology.h>
 #include <linux/notifier.h>
+#include <linux/property.h>
 
 #include <asm/byteorder.h>
 #include <asm/errno.h>