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Date:	Mon, 13 Oct 2014 14:47:42 +0200
From:	Grant Likely <grant.likely@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Aaron Lu <aaron.lu@...el.com>, devicetree@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Bryan Wu <cooloney@...il.com>, Arnd Bergmann <arnd@...db.de>,
	Darren Hart <dvhart@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 01/13] ACPI: Add support for device specific properties

On Tue, 07 Oct 2014 02:12:23 +0200
, "Rafael J. Wysocki" <rjw@...ysocki.net>
 wrote:
> From: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 
> Device Tree is used in many embedded systems to describe the system
> configuration to the OS. It supports attaching properties or name-value
> pairs to the devices it describe. With these properties one can pass
> additional information to the drivers that would not be available
> otherwise.
> 
> ACPI is another configuration mechanism (among other things) typically
> seen, but not limited to, x86 machines. ACPI allows passing arbitrary
> data from methods but there has not been mechanism equivalent to Device
> Tree until the introduction of _DSD in the recent publication of the
> ACPI 5.1 specification.
> 
> In order to facilitate ACPI usage in systems where Device Tree is
> typically used, it would be beneficial to standardize a way to retrieve
> Device Tree style properties from ACPI devices, which is what we do in
> this patch.
> 
> If a given device described in ACPI namespace wants to export properties it
> must implement _DSD method (Device Specific Data, introduced with ACPI 5.1)
> that returns the properties in a package of packages. For example:
> 
> 	Name (_DSD, Package () {
> 		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> 		Package () {
> 			Package () {"name1", <VALUE1>},
> 			Package () {"name2", <VALUE2>},
> 			...
> 		}
> 	})
> 
> The UUID reserved for properties is daffd814-6eba-4d8c-8a91-bc9bbf4aa301
> and is documented in the ACPI 5.1 companion document called "_DSD
> Implementation Guide" [1], [2].
> 
> We add several helper functions that can be used to extract these
> properties and convert them to different Linux data types.
> 
> The ultimate goal is that we only have one device property API that
> retrieves the requested properties from Device Tree or from ACPI
> transparent to the caller.
> 
> [1] http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel.htm
> [2] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
> 
> Reviewed-by: Hanjun Guo <hanjun.guo@...aro.org>
> Reviewed-by: Josh Triplett <josh@...htriplett.org>
> Signed-off-by: Darren Hart <dvhart@...ux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

This patch seems fine.

Reviewed-by: Grant Likely <grant.likely@...aro.org>

> ---
>  drivers/acpi/Makefile   |    1 
>  drivers/acpi/internal.h |    6 
>  drivers/acpi/property.c |  364 ++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/scan.c     |    2 
>  include/acpi/acpi_bus.h |    7 
>  include/linux/acpi.h    |   40 +++++
>  6 files changed, 420 insertions(+)
>  create mode 100644 drivers/acpi/property.c
> 
> Index: linux-pm/drivers/acpi/Makefile
> ===================================================================
> --- linux-pm.orig/drivers/acpi/Makefile
> +++ linux-pm/drivers/acpi/Makefile
> @@ -46,6 +46,7 @@ acpi-y				+= acpi_pnp.o
>  acpi-y				+= power.o
>  acpi-y				+= event.o
>  acpi-y				+= sysfs.o
> +acpi-y				+= property.o
>  acpi-$(CONFIG_X86)		+= acpi_cmos_rtc.o
>  acpi-$(CONFIG_DEBUG_FS)		+= debugfs.o
>  acpi-$(CONFIG_ACPI_NUMA)	+= numa.o
> Index: linux-pm/drivers/acpi/internal.h
> ===================================================================
> --- linux-pm.orig/drivers/acpi/internal.h
> +++ linux-pm/drivers/acpi/internal.h
> @@ -181,4 +181,10 @@ struct platform_device *acpi_create_plat
>  bool acpi_osi_is_win8(void);
>  #endif
>  
> +/*--------------------------------------------------------------------------
> +				Device properties
> +  -------------------------------------------------------------------------- */
> +void acpi_init_properties(struct acpi_device *adev);
> +void acpi_free_properties(struct acpi_device *adev);
> +
>  #endif /* _ACPI_INTERNAL_H_ */
> Index: linux-pm/drivers/acpi/property.c
> ===================================================================
> --- /dev/null
> +++ linux-pm/drivers/acpi/property.c
> @@ -0,0 +1,364 @@
> +/*
> + * ACPI device specific properties support.
> + *
> + * Copyright (C) 2014, Intel Corporation
> + * All rights reserved.
> + *
> + * Authors: Mika Westerberg <mika.westerberg@...ux.intel.com>
> + *          Darren Hart <dvhart@...ux.intel.com>
> + *          Rafael J. Wysocki <rafael.j.wysocki@...el.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/acpi.h>
> +#include <linux/device.h>
> +#include <linux/export.h>
> +
> +#include "internal.h"
> +
> +/* ACPI _DSD device properties UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301 */
> +static const u8 prp_uuid[16] = {
> +	0x14, 0xd8, 0xff, 0xda, 0xba, 0x6e, 0x8c, 0x4d,
> +	0x8a, 0x91, 0xbc, 0x9b, 0xbf, 0x4a, 0xa3, 0x01
> +};
> +
> +static bool acpi_property_value_ok(const union acpi_object *value)
> +{
> +	int j;
> +
> +	/*
> +	 * The value must be an integer, a string, a reference, or a package
> +	 * whose every element must be an integer, a string, or a reference.
> +	 */
> +	switch (value->type) {
> +	case ACPI_TYPE_INTEGER:
> +	case ACPI_TYPE_STRING:
> +	case ACPI_TYPE_LOCAL_REFERENCE:
> +		return true;
> +
> +	case ACPI_TYPE_PACKAGE:
> +		for (j = 0; j < value->package.count; j++)
> +			switch (value->package.elements[j].type) {
> +			case ACPI_TYPE_INTEGER:
> +			case ACPI_TYPE_STRING:
> +			case ACPI_TYPE_LOCAL_REFERENCE:
> +				continue;
> +
> +			default:
> +				return false;
> +			}
> +
> +		return true;
> +	}
> +	return false;
> +}
> +
> +static bool acpi_properties_format_valid(const union acpi_object *properties)
> +{
> +	int i;
> +
> +	for (i = 0; i < properties->package.count; i++) {
> +		const union acpi_object *property;
> +
> +		property = &properties->package.elements[i];
> +		/*
> +		 * Only two elements allowed, the first one must be a string and
> +		 * the second one has to satisfy certain conditions.
> +		 */
> +		if (property->package.count != 2
> +		    || property->package.elements[0].type != ACPI_TYPE_STRING
> +		    || !acpi_property_value_ok(&property->package.elements[1]))
> +			return false;
> +	}
> +	return true;
> +}
> +
> +void acpi_init_properties(struct acpi_device *adev)
> +{
> +	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
> +	const union acpi_object *desc;
> +	acpi_status status;
> +	int i;
> +
> +	status = acpi_evaluate_object_typed(adev->handle, "_DSD", NULL, &buf,
> +					    ACPI_TYPE_PACKAGE);
> +	if (ACPI_FAILURE(status))
> +		return;
> +
> +	desc = buf.pointer;
> +	if (desc->package.count % 2)
> +		goto fail;
> +
> +	/* Look for the device properties UUID. */
> +	for (i = 0; i < desc->package.count; i += 2) {
> +		const union acpi_object *uuid, *properties;
> +
> +		uuid = &desc->package.elements[i];
> +		properties = &desc->package.elements[i + 1];
> +
> +		/*
> +		 * The first element must be a UUID and the second one must be
> +		 * a package.
> +		 */
> +		if (uuid->type != ACPI_TYPE_BUFFER || uuid->buffer.length != 16
> +		    || properties->type != ACPI_TYPE_PACKAGE)
> +			break;
> +
> +		if (memcmp(uuid->buffer.pointer, prp_uuid, sizeof(prp_uuid)))
> +			continue;
> +
> +		/*
> +		 * We found the matching UUID. Now validate the format of the
> +		 * package immediately following it.
> +		 */
> +		if (!acpi_properties_format_valid(properties))
> +			break;
> +
> +		adev->data.pointer = buf.pointer;
> +		adev->data.properties = properties;
> +		return;
> +	}
> +
> + fail:
> +	dev_warn(&adev->dev, "Returned _DSD data is not valid, skipping\n");
> +	ACPI_FREE(buf.pointer);
> +}
> +
> +void acpi_free_properties(struct acpi_device *adev)
> +{
> +	ACPI_FREE((void *)adev->data.pointer);
> +	adev->data.pointer = NULL;
> +	adev->data.properties = NULL;
> +}
> +
> +/**
> + * acpi_dev_get_property - return an ACPI property with given name
> + * @adev: ACPI device to get property
> + * @name: Name of the property
> + * @type: Expected property type
> + * @obj: Location to store the property value (if not %NULL)
> + *
> + * Look up a property with @name and store a pointer to the resulting ACPI
> + * object at the location pointed to by @obj if found.
> + *
> + * Callers must not attempt to free the returned objects.  These objects will be
> + * freed by the ACPI core automatically during the removal of @adev.
> + *
> + * Return: %0 if property with @name has been found (success),
> + *         %-EINVAL if the arguments are invalid,
> + *         %-ENODATA if the property doesn't exist,
> + *         %-EPROTO if the property value type doesn't match @type.
> + */
> +int acpi_dev_get_property(struct acpi_device *adev, const char *name,
> +			  acpi_object_type type, const union acpi_object **obj)
> +{
> +	const union acpi_object *properties;
> +	int i;
> +
> +	if (!adev || !name)
> +		return -EINVAL;
> +
> +	if (!adev->data.pointer || !adev->data.properties)
> +		return -ENODATA;
> +
> +	properties = adev->data.properties;
> +	for (i = 0; i < properties->package.count; i++) {
> +		const union acpi_object *propname, *propvalue;
> +		const union acpi_object *property;
> +
> +		property = &properties->package.elements[i];
> +
> +		propname = &property->package.elements[0];
> +		propvalue = &property->package.elements[1];
> +
> +		if (!strcmp(name, propname->string.pointer)) {
> +			if (type != ACPI_TYPE_ANY && propvalue->type != type)
> +				return -EPROTO;
> +			else if (obj)
> +				*obj = propvalue;
> +
> +			return 0;
> +		}
> +	}
> +	return -ENODATA;
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_get_property);
> +
> +/**
> + * acpi_dev_get_property_array - return an ACPI array property with given name
> + * @adev: ACPI device to get property
> + * @name: Name of the property
> + * @type: Expected type of array elements
> + * @obj: Location to store a pointer to the property value (if not NULL)
> + *
> + * Look up an array property with @name and store a pointer to the resulting
> + * ACPI object at the location pointed to by @obj if found.
> + *
> + * Callers must not attempt to free the returned objects.  Those objects will be
> + * freed by the ACPI core automatically during the removal of @adev.
> + *
> + * Return: %0 if array property (package) with @name has been found (success),
> + *         %-EINVAL if the arguments are invalid,
> + *         %-ENODATA if the property doesn't exist,
> + *         %-EPROTO if the property is not a package or the type of its elements
> + *           doesn't match @type.
> + */
> +int acpi_dev_get_property_array(struct acpi_device *adev, const char *name,
> +				acpi_object_type type,
> +				const union acpi_object **obj)
> +{
> +	const union acpi_object *prop;
> +	int ret, i;
> +
> +	ret = acpi_dev_get_property(adev, name, ACPI_TYPE_PACKAGE, &prop);
> +	if (ret)
> +		return ret;
> +
> +	if (type != ACPI_TYPE_ANY) {
> +		/* Check that all elements are of correct type. */
> +		for (i = 0; i < prop->package.count; i++)
> +			if (prop->package.elements[i].type != type)
> +				return -EPROTO;
> +	}
> +	if (obj)
> +		*obj = prop;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_get_property_array);
> +
> +/**
> + * acpi_dev_get_property_reference - returns handle to the referenced object
> + * @adev: ACPI device to get property
> + * @name: Name of the property
> + * @size_prop: Name of the "size" property in referenced object
> + * @index: Index of the reference to return
> + * @args: Location to store the returned reference with optional arguments
> + *
> + * Find property with @name, verifify that it is a package containing at least
> + * one object reference and if so, store the ACPI device object pointer to the
> + * target object in @args->adev.
> + *
> + * If the reference includes arguments (@size_prop is not %NULL) follow the
> + * reference and check whether or not there is an integer property @size_prop
> + * under the target object and if so, whether or not its value matches the
> + * number of arguments that follow the reference.  If there's more than one
> + * reference in the property value package, @index is used to select the one to
> + * return.
> + *
> + * Return: %0 on success, negative error code on failure.
> + */
> +int acpi_dev_get_property_reference(struct acpi_device *adev, const char *name,
> +				    const char *size_prop, size_t index,
> +				    struct acpi_reference_args *args)
> +{
> +	const union acpi_object *element, *end;
> +	const union acpi_object *obj;
> +	struct acpi_device *device;
> +	int ret, idx = 0;
> +
> +	ret = acpi_dev_get_property(adev, name, ACPI_TYPE_ANY, &obj);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * The simplest case is when the value is a single reference.  Just
> +	 * return that reference then.
> +	 */
> +	if (obj->type == ACPI_TYPE_LOCAL_REFERENCE) {
> +		if (size_prop || index)
> +			return -EINVAL;
> +
> +		ret = acpi_bus_get_device(obj->reference.handle, &device);
> +		if (ret)
> +			return ret;
> +
> +		args->adev = device;
> +		args->nargs = 0;
> +		return 0;
> +	}
> +
> +	/*
> +	 * If it is not a single reference, then it is a package of
> +	 * references followed by number of ints as follows:
> +	 *
> +	 *  Package () { REF, INT, REF, INT, INT }
> +	 *
> +	 * The index argument is then used to determine which reference
> +	 * the caller wants (along with the arguments).
> +	 */
> +	if (obj->type != ACPI_TYPE_PACKAGE || index >= obj->package.count)
> +		return -EPROTO;
> +
> +	element = obj->package.elements;
> +	end = element + obj->package.count;
> +
> +	while (element < end) {
> +		u32 nargs, i;
> +
> +		if (element->type != ACPI_TYPE_LOCAL_REFERENCE)
> +			return -EPROTO;
> +
> +		ret = acpi_bus_get_device(element->reference.handle, &device);
> +		if (ret)
> +			return -ENODEV;
> +
> +		element++;
> +		nargs = 0;
> +
> +		if (size_prop) {
> +			const union acpi_object *prop;
> +
> +			/*
> +			 * Find out how many arguments the refenced object
> +			 * expects by reading its size_prop property.
> +			 */
> +			ret = acpi_dev_get_property(device, size_prop,
> +						    ACPI_TYPE_INTEGER, &prop);
> +			if (ret)
> +				return ret;
> +
> +			nargs = prop->integer.value;
> +			if (nargs > MAX_ACPI_REFERENCE_ARGS
> +			    || element + nargs > end)
> +				return -EPROTO;
> +
> +			/*
> +			 * Skip to the start of the arguments and verify
> +			 * that they all are in fact integers.
> +			 */
> +			for (i = 0; i < nargs; i++)
> +				if (element[i].type != ACPI_TYPE_INTEGER)
> +					return -EPROTO;
> +		} else {
> +			/* assume following integer elements are all args */
> +			for (i = 0; element + i < end; i++) {
> +				int type = element[i].type;
> +
> +				if (type == ACPI_TYPE_INTEGER)
> +					nargs++;
> +				else if (type == ACPI_TYPE_LOCAL_REFERENCE)
> +					break;
> +				else
> +					return -EPROTO;
> +			}
> +		}
> +
> +		if (idx++ == index) {
> +			args->adev = device;
> +			args->nargs = nargs;
> +			for (i = 0; i < nargs; i++)
> +				args->args[i] = element[i].integer.value;
> +
> +			return 0;
> +		}
> +
> +		element += nargs;
> +	}
> +
> +	return -EPROTO;
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_get_property_reference);
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -884,6 +884,7 @@ static void acpi_device_release(struct d
>  {
>  	struct acpi_device *acpi_dev = to_acpi_device(dev);
>  
> +	acpi_free_properties(acpi_dev);
>  	acpi_free_pnp_ids(&acpi_dev->pnp);
>  	acpi_free_power_resources_lists(acpi_dev);
>  	kfree(acpi_dev);
> @@ -1888,6 +1889,7 @@ void acpi_init_device_object(struct acpi
>  	acpi_set_device_status(device, sta);
>  	acpi_device_get_busid(device);
>  	acpi_set_pnp_ids(handle, &device->pnp, type);
> +	acpi_init_properties(device);
>  	acpi_bus_get_flags(device);
>  	device->flags.match_driver = false;
>  	device->flags.initialized = true;
> Index: linux-pm/include/acpi/acpi_bus.h
> ===================================================================
> --- linux-pm.orig/include/acpi/acpi_bus.h
> +++ linux-pm/include/acpi/acpi_bus.h
> @@ -337,6 +337,12 @@ struct acpi_device_physical_node {
>  	bool put_online:1;
>  };
>  
> +/* ACPI Device Specific Data (_DSD) */
> +struct acpi_device_data {
> +	const union acpi_object *pointer;
> +	const union acpi_object *properties;
> +};
> +
>  /* Device */
>  struct acpi_device {
>  	int device_type;
> @@ -353,6 +359,7 @@ struct acpi_device {
>  	struct acpi_device_wakeup wakeup;
>  	struct acpi_device_perf performance;
>  	struct acpi_device_dir dir;
> +	struct acpi_device_data data;
>  	struct acpi_scan_handler *handler;
>  	struct acpi_hotplug_context *hp;
>  	struct acpi_driver *driver;
> Index: linux-pm/include/linux/acpi.h
> ===================================================================
> --- linux-pm.orig/include/linux/acpi.h
> +++ linux-pm/include/linux/acpi.h
> @@ -658,4 +658,44 @@ do {									\
>  #endif
>  #endif
>  
> +/* Device properties */
> +
> +#define MAX_ACPI_REFERENCE_ARGS	8
> +struct acpi_reference_args {
> +	struct acpi_device *adev;
> +	size_t nargs;
> +	u64 args[MAX_ACPI_REFERENCE_ARGS];
> +};
> +
> +#ifdef CONFIG_ACPI
> +int acpi_dev_get_property(struct acpi_device *adev, const char *name,
> +			  acpi_object_type type, const union acpi_object **obj);
> +int acpi_dev_get_property_array(struct acpi_device *adev, const char *name,
> +				acpi_object_type type,
> +				const union acpi_object **obj);
> +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);
> +#else
> +static inline int acpi_dev_get_property(struct acpi_device *adev,
> +					const char *name, acpi_object_type type,
> +					const union acpi_object **obj)
> +{
> +	return -ENXIO;
> +}
> +static inline int acpi_dev_get_property_array(struct acpi_device *adev,
> +					      const char *name,
> +					      acpi_object_type type,
> +					      const union acpi_object **obj)
> +{
> +	return -ENXIO;
> +}
> +static inline 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)
> +{
> +	return -ENXIO;
> +}
> +#endif
> +
>  #endif	/*_LINUX_ACPI_H*/
> 

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